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TOMOYO Linux Cross Reference
Linux/include/linux/skbuff.h

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  1 /*
  2  *      Definitions for the 'struct sk_buff' memory handlers.
  3  *
  4  *      Authors:
  5  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  6  *              Florian La Roche, <rzsfl@rz.uni-sb.de>
  7  *
  8  *      This program is free software; you can redistribute it and/or
  9  *      modify it under the terms of the GNU General Public License
 10  *      as published by the Free Software Foundation; either version
 11  *      2 of the License, or (at your option) any later version.
 12  */
 13 
 14 #ifndef _LINUX_SKBUFF_H
 15 #define _LINUX_SKBUFF_H
 16 
 17 #include <linux/kernel.h>
 18 #include <linux/compiler.h>
 19 #include <linux/time.h>
 20 #include <linux/bug.h>
 21 #include <linux/cache.h>
 22 #include <linux/rbtree.h>
 23 #include <linux/socket.h>
 24 #include <linux/refcount.h>
 25 
 26 #include <linux/atomic.h>
 27 #include <asm/types.h>
 28 #include <linux/spinlock.h>
 29 #include <linux/net.h>
 30 #include <linux/textsearch.h>
 31 #include <net/checksum.h>
 32 #include <linux/rcupdate.h>
 33 #include <linux/hrtimer.h>
 34 #include <linux/dma-mapping.h>
 35 #include <linux/netdev_features.h>
 36 #include <linux/sched.h>
 37 #include <linux/sched/clock.h>
 38 #include <net/flow_dissector.h>
 39 #include <linux/splice.h>
 40 #include <linux/in6.h>
 41 #include <linux/if_packet.h>
 42 #include <net/flow.h>
 43 
 44 /* The interface for checksum offload between the stack and networking drivers
 45  * is as follows...
 46  *
 47  * A. IP checksum related features
 48  *
 49  * Drivers advertise checksum offload capabilities in the features of a device.
 50  * From the stack's point of view these are capabilities offered by the driver,
 51  * a driver typically only advertises features that it is capable of offloading
 52  * to its device.
 53  *
 54  * The checksum related features are:
 55  *
 56  *      NETIF_F_HW_CSUM - The driver (or its device) is able to compute one
 57  *                        IP (one's complement) checksum for any combination
 58  *                        of protocols or protocol layering. The checksum is
 59  *                        computed and set in a packet per the CHECKSUM_PARTIAL
 60  *                        interface (see below).
 61  *
 62  *      NETIF_F_IP_CSUM - Driver (device) is only able to checksum plain
 63  *                        TCP or UDP packets over IPv4. These are specifically
 64  *                        unencapsulated packets of the form IPv4|TCP or
 65  *                        IPv4|UDP where the Protocol field in the IPv4 header
 66  *                        is TCP or UDP. The IPv4 header may contain IP options
 67  *                        This feature cannot be set in features for a device
 68  *                        with NETIF_F_HW_CSUM also set. This feature is being
 69  *                        DEPRECATED (see below).
 70  *
 71  *      NETIF_F_IPV6_CSUM - Driver (device) is only able to checksum plain
 72  *                        TCP or UDP packets over IPv6. These are specifically
 73  *                        unencapsulated packets of the form IPv6|TCP or
 74  *                        IPv4|UDP where the Next Header field in the IPv6
 75  *                        header is either TCP or UDP. IPv6 extension headers
 76  *                        are not supported with this feature. This feature
 77  *                        cannot be set in features for a device with
 78  *                        NETIF_F_HW_CSUM also set. This feature is being
 79  *                        DEPRECATED (see below).
 80  *
 81  *      NETIF_F_RXCSUM - Driver (device) performs receive checksum offload.
 82  *                       This flag is used only used to disable the RX checksum
 83  *                       feature for a device. The stack will accept receive
 84  *                       checksum indication in packets received on a device
 85  *                       regardless of whether NETIF_F_RXCSUM is set.
 86  *
 87  * B. Checksumming of received packets by device. Indication of checksum
 88  *    verification is in set skb->ip_summed. Possible values are:
 89  *
 90  * CHECKSUM_NONE:
 91  *
 92  *   Device did not checksum this packet e.g. due to lack of capabilities.
 93  *   The packet contains full (though not verified) checksum in packet but
 94  *   not in skb->csum. Thus, skb->csum is undefined in this case.
 95  *
 96  * CHECKSUM_UNNECESSARY:
 97  *
 98  *   The hardware you're dealing with doesn't calculate the full checksum
 99  *   (as in CHECKSUM_COMPLETE), but it does parse headers and verify checksums
100  *   for specific protocols. For such packets it will set CHECKSUM_UNNECESSARY
101  *   if their checksums are okay. skb->csum is still undefined in this case
102  *   though. A driver or device must never modify the checksum field in the
103  *   packet even if checksum is verified.
104  *
105  *   CHECKSUM_UNNECESSARY is applicable to following protocols:
106  *     TCP: IPv6 and IPv4.
107  *     UDP: IPv4 and IPv6. A device may apply CHECKSUM_UNNECESSARY to a
108  *       zero UDP checksum for either IPv4 or IPv6, the networking stack
109  *       may perform further validation in this case.
110  *     GRE: only if the checksum is present in the header.
111  *     SCTP: indicates the CRC in SCTP header has been validated.
112  *     FCOE: indicates the CRC in FC frame has been validated.
113  *
114  *   skb->csum_level indicates the number of consecutive checksums found in
115  *   the packet minus one that have been verified as CHECKSUM_UNNECESSARY.
116  *   For instance if a device receives an IPv6->UDP->GRE->IPv4->TCP packet
117  *   and a device is able to verify the checksums for UDP (possibly zero),
118  *   GRE (checksum flag is set), and TCP-- skb->csum_level would be set to
119  *   two. If the device were only able to verify the UDP checksum and not
120  *   GRE, either because it doesn't support GRE checksum of because GRE
121  *   checksum is bad, skb->csum_level would be set to zero (TCP checksum is
122  *   not considered in this case).
123  *
124  * CHECKSUM_COMPLETE:
125  *
126  *   This is the most generic way. The device supplied checksum of the _whole_
127  *   packet as seen by netif_rx() and fills out in skb->csum. Meaning, the
128  *   hardware doesn't need to parse L3/L4 headers to implement this.
129  *
130  *   Notes:
131  *   - Even if device supports only some protocols, but is able to produce
132  *     skb->csum, it MUST use CHECKSUM_COMPLETE, not CHECKSUM_UNNECESSARY.
133  *   - CHECKSUM_COMPLETE is not applicable to SCTP and FCoE protocols.
134  *
135  * CHECKSUM_PARTIAL:
136  *
137  *   A checksum is set up to be offloaded to a device as described in the
138  *   output description for CHECKSUM_PARTIAL. This may occur on a packet
139  *   received directly from another Linux OS, e.g., a virtualized Linux kernel
140  *   on the same host, or it may be set in the input path in GRO or remote
141  *   checksum offload. For the purposes of checksum verification, the checksum
142  *   referred to by skb->csum_start + skb->csum_offset and any preceding
143  *   checksums in the packet are considered verified. Any checksums in the
144  *   packet that are after the checksum being offloaded are not considered to
145  *   be verified.
146  *
147  * C. Checksumming on transmit for non-GSO. The stack requests checksum offload
148  *    in the skb->ip_summed for a packet. Values are:
149  *
150  * CHECKSUM_PARTIAL:
151  *
152  *   The driver is required to checksum the packet as seen by hard_start_xmit()
153  *   from skb->csum_start up to the end, and to record/write the checksum at
154  *   offset skb->csum_start + skb->csum_offset. A driver may verify that the
155  *   csum_start and csum_offset values are valid values given the length and
156  *   offset of the packet, however they should not attempt to validate that the
157  *   checksum refers to a legitimate transport layer checksum-- it is the
158  *   purview of the stack to validate that csum_start and csum_offset are set
159  *   correctly.
160  *
161  *   When the stack requests checksum offload for a packet, the driver MUST
162  *   ensure that the checksum is set correctly. A driver can either offload the
163  *   checksum calculation to the device, or call skb_checksum_help (in the case
164  *   that the device does not support offload for a particular checksum).
165  *
166  *   NETIF_F_IP_CSUM and NETIF_F_IPV6_CSUM are being deprecated in favor of
167  *   NETIF_F_HW_CSUM. New devices should use NETIF_F_HW_CSUM to indicate
168  *   checksum offload capability.
169  *   skb_csum_hwoffload_help() can be called to resolve CHECKSUM_PARTIAL based
170  *   on network device checksumming capabilities: if a packet does not match
171  *   them, skb_checksum_help or skb_crc32c_help (depending on the value of
172  *   csum_not_inet, see item D.) is called to resolve the checksum.
173  *
174  * CHECKSUM_NONE:
175  *
176  *   The skb was already checksummed by the protocol, or a checksum is not
177  *   required.
178  *
179  * CHECKSUM_UNNECESSARY:
180  *
181  *   This has the same meaning on as CHECKSUM_NONE for checksum offload on
182  *   output.
183  *
184  * CHECKSUM_COMPLETE:
185  *   Not used in checksum output. If a driver observes a packet with this value
186  *   set in skbuff, if should treat as CHECKSUM_NONE being set.
187  *
188  * D. Non-IP checksum (CRC) offloads
189  *
190  *   NETIF_F_SCTP_CRC - This feature indicates that a device is capable of
191  *     offloading the SCTP CRC in a packet. To perform this offload the stack
192  *     will set set csum_start and csum_offset accordingly, set ip_summed to
193  *     CHECKSUM_PARTIAL and set csum_not_inet to 1, to provide an indication in
194  *     the skbuff that the CHECKSUM_PARTIAL refers to CRC32c.
195  *     A driver that supports both IP checksum offload and SCTP CRC32c offload
196  *     must verify which offload is configured for a packet by testing the
197  *     value of skb->csum_not_inet; skb_crc32c_csum_help is provided to resolve
198  *     CHECKSUM_PARTIAL on skbs where csum_not_inet is set to 1.
199  *
200  *   NETIF_F_FCOE_CRC - This feature indicates that a device is capable of
201  *     offloading the FCOE CRC in a packet. To perform this offload the stack
202  *     will set ip_summed to CHECKSUM_PARTIAL and set csum_start and csum_offset
203  *     accordingly. Note the there is no indication in the skbuff that the
204  *     CHECKSUM_PARTIAL refers to an FCOE checksum, a driver that supports
205  *     both IP checksum offload and FCOE CRC offload must verify which offload
206  *     is configured for a packet presumably by inspecting packet headers.
207  *
208  * E. Checksumming on output with GSO.
209  *
210  * In the case of a GSO packet (skb_is_gso(skb) is true), checksum offload
211  * is implied by the SKB_GSO_* flags in gso_type. Most obviously, if the
212  * gso_type is SKB_GSO_TCPV4 or SKB_GSO_TCPV6, TCP checksum offload as
213  * part of the GSO operation is implied. If a checksum is being offloaded
214  * with GSO then ip_summed is CHECKSUM_PARTIAL, csum_start and csum_offset
215  * are set to refer to the outermost checksum being offload (two offloaded
216  * checksums are possible with UDP encapsulation).
217  */
218 
219 /* Don't change this without changing skb_csum_unnecessary! */
220 #define CHECKSUM_NONE           0
221 #define CHECKSUM_UNNECESSARY    1
222 #define CHECKSUM_COMPLETE       2
223 #define CHECKSUM_PARTIAL        3
224 
225 /* Maximum value in skb->csum_level */
226 #define SKB_MAX_CSUM_LEVEL      3
227 
228 #define SKB_DATA_ALIGN(X)       ALIGN(X, SMP_CACHE_BYTES)
229 #define SKB_WITH_OVERHEAD(X)    \
230         ((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
231 #define SKB_MAX_ORDER(X, ORDER) \
232         SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
233 #define SKB_MAX_HEAD(X)         (SKB_MAX_ORDER((X), 0))
234 #define SKB_MAX_ALLOC           (SKB_MAX_ORDER(0, 2))
235 
236 /* return minimum truesize of one skb containing X bytes of data */
237 #define SKB_TRUESIZE(X) ((X) +                                          \
238                          SKB_DATA_ALIGN(sizeof(struct sk_buff)) +       \
239                          SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
240 
241 struct net_device;
242 struct scatterlist;
243 struct pipe_inode_info;
244 struct iov_iter;
245 struct napi_struct;
246 
247 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
248 struct nf_conntrack {
249         atomic_t use;
250 };
251 #endif
252 
253 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
254 struct nf_bridge_info {
255         refcount_t              use;
256         enum {
257                 BRNF_PROTO_UNCHANGED,
258                 BRNF_PROTO_8021Q,
259                 BRNF_PROTO_PPPOE
260         } orig_proto:8;
261         u8                      pkt_otherhost:1;
262         u8                      in_prerouting:1;
263         u8                      bridged_dnat:1;
264         __u16                   frag_max_size;
265         struct net_device       *physindev;
266 
267         /* always valid & non-NULL from FORWARD on, for physdev match */
268         struct net_device       *physoutdev;
269         union {
270                 /* prerouting: detect dnat in orig/reply direction */
271                 __be32          ipv4_daddr;
272                 struct in6_addr ipv6_daddr;
273 
274                 /* after prerouting + nat detected: store original source
275                  * mac since neigh resolution overwrites it, only used while
276                  * skb is out in neigh layer.
277                  */
278                 char neigh_header[8];
279         };
280 };
281 #endif
282 
283 struct sk_buff_head {
284         /* These two members must be first. */
285         struct sk_buff  *next;
286         struct sk_buff  *prev;
287 
288         __u32           qlen;
289         spinlock_t      lock;
290 };
291 
292 struct sk_buff;
293 
294 /* To allow 64K frame to be packed as single skb without frag_list we
295  * require 64K/PAGE_SIZE pages plus 1 additional page to allow for
296  * buffers which do not start on a page boundary.
297  *
298  * Since GRO uses frags we allocate at least 16 regardless of page
299  * size.
300  */
301 #if (65536/PAGE_SIZE + 1) < 16
302 #define MAX_SKB_FRAGS 16UL
303 #else
304 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 1)
305 #endif
306 extern int sysctl_max_skb_frags;
307 
308 /* Set skb_shinfo(skb)->gso_size to this in case you want skb_segment to
309  * segment using its current segmentation instead.
310  */
311 #define GSO_BY_FRAGS    0xFFFF
312 
313 typedef struct skb_frag_struct skb_frag_t;
314 
315 struct skb_frag_struct {
316         struct {
317                 struct page *p;
318         } page;
319 #if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
320         __u32 page_offset;
321         __u32 size;
322 #else
323         __u16 page_offset;
324         __u16 size;
325 #endif
326 };
327 
328 static inline unsigned int skb_frag_size(const skb_frag_t *frag)
329 {
330         return frag->size;
331 }
332 
333 static inline void skb_frag_size_set(skb_frag_t *frag, unsigned int size)
334 {
335         frag->size = size;
336 }
337 
338 static inline void skb_frag_size_add(skb_frag_t *frag, int delta)
339 {
340         frag->size += delta;
341 }
342 
343 static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
344 {
345         frag->size -= delta;
346 }
347 
348 static inline bool skb_frag_must_loop(struct page *p)
349 {
350 #if defined(CONFIG_HIGHMEM)
351         if (PageHighMem(p))
352                 return true;
353 #endif
354         return false;
355 }
356 
357 /**
358  *      skb_frag_foreach_page - loop over pages in a fragment
359  *
360  *      @f:             skb frag to operate on
361  *      @f_off:         offset from start of f->page.p
362  *      @f_len:         length from f_off to loop over
363  *      @p:             (temp var) current page
364  *      @p_off:         (temp var) offset from start of current page,
365  *                                 non-zero only on first page.
366  *      @p_len:         (temp var) length in current page,
367  *                                 < PAGE_SIZE only on first and last page.
368  *      @copied:        (temp var) length so far, excluding current p_len.
369  *
370  *      A fragment can hold a compound page, in which case per-page
371  *      operations, notably kmap_atomic, must be called for each
372  *      regular page.
373  */
374 #define skb_frag_foreach_page(f, f_off, f_len, p, p_off, p_len, copied) \
375         for (p = skb_frag_page(f) + ((f_off) >> PAGE_SHIFT),            \
376              p_off = (f_off) & (PAGE_SIZE - 1),                         \
377              p_len = skb_frag_must_loop(p) ?                            \
378              min_t(u32, f_len, PAGE_SIZE - p_off) : f_len,              \
379              copied = 0;                                                \
380              copied < f_len;                                            \
381              copied += p_len, p++, p_off = 0,                           \
382              p_len = min_t(u32, f_len - copied, PAGE_SIZE))             \
383 
384 #define HAVE_HW_TIME_STAMP
385 
386 /**
387  * struct skb_shared_hwtstamps - hardware time stamps
388  * @hwtstamp:   hardware time stamp transformed into duration
389  *              since arbitrary point in time
390  *
391  * Software time stamps generated by ktime_get_real() are stored in
392  * skb->tstamp.
393  *
394  * hwtstamps can only be compared against other hwtstamps from
395  * the same device.
396  *
397  * This structure is attached to packets as part of the
398  * &skb_shared_info. Use skb_hwtstamps() to get a pointer.
399  */
400 struct skb_shared_hwtstamps {
401         ktime_t hwtstamp;
402 };
403 
404 /* Definitions for tx_flags in struct skb_shared_info */
405 enum {
406         /* generate hardware time stamp */
407         SKBTX_HW_TSTAMP = 1 << 0,
408 
409         /* generate software time stamp when queueing packet to NIC */
410         SKBTX_SW_TSTAMP = 1 << 1,
411 
412         /* device driver is going to provide hardware time stamp */
413         SKBTX_IN_PROGRESS = 1 << 2,
414 
415         /* device driver supports TX zero-copy buffers */
416         SKBTX_DEV_ZEROCOPY = 1 << 3,
417 
418         /* generate wifi status information (where possible) */
419         SKBTX_WIFI_STATUS = 1 << 4,
420 
421         /* This indicates at least one fragment might be overwritten
422          * (as in vmsplice(), sendfile() ...)
423          * If we need to compute a TX checksum, we'll need to copy
424          * all frags to avoid possible bad checksum
425          */
426         SKBTX_SHARED_FRAG = 1 << 5,
427 
428         /* generate software time stamp when entering packet scheduling */
429         SKBTX_SCHED_TSTAMP = 1 << 6,
430 };
431 
432 #define SKBTX_ZEROCOPY_FRAG     (SKBTX_DEV_ZEROCOPY | SKBTX_SHARED_FRAG)
433 #define SKBTX_ANY_SW_TSTAMP     (SKBTX_SW_TSTAMP    | \
434                                  SKBTX_SCHED_TSTAMP)
435 #define SKBTX_ANY_TSTAMP        (SKBTX_HW_TSTAMP | SKBTX_ANY_SW_TSTAMP)
436 
437 /*
438  * The callback notifies userspace to release buffers when skb DMA is done in
439  * lower device, the skb last reference should be 0 when calling this.
440  * The zerocopy_success argument is true if zero copy transmit occurred,
441  * false on data copy or out of memory error caused by data copy attempt.
442  * The ctx field is used to track device context.
443  * The desc field is used to track userspace buffer index.
444  */
445 struct ubuf_info {
446         void (*callback)(struct ubuf_info *, bool zerocopy_success);
447         union {
448                 struct {
449                         unsigned long desc;
450                         void *ctx;
451                 };
452                 struct {
453                         u32 id;
454                         u16 len;
455                         u16 zerocopy:1;
456                         u32 bytelen;
457                 };
458         };
459         refcount_t refcnt;
460 
461         struct mmpin {
462                 struct user_struct *user;
463                 unsigned int num_pg;
464         } mmp;
465 };
466 
467 #define skb_uarg(SKB)   ((struct ubuf_info *)(skb_shinfo(SKB)->destructor_arg))
468 
469 struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size);
470 struct ubuf_info *sock_zerocopy_realloc(struct sock *sk, size_t size,
471                                         struct ubuf_info *uarg);
472 
473 static inline void sock_zerocopy_get(struct ubuf_info *uarg)
474 {
475         refcount_inc(&uarg->refcnt);
476 }
477 
478 void sock_zerocopy_put(struct ubuf_info *uarg);
479 void sock_zerocopy_put_abort(struct ubuf_info *uarg);
480 
481 void sock_zerocopy_callback(struct ubuf_info *uarg, bool success);
482 
483 int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
484                              struct msghdr *msg, int len,
485                              struct ubuf_info *uarg);
486 
487 /* This data is invariant across clones and lives at
488  * the end of the header data, ie. at skb->end.
489  */
490 struct skb_shared_info {
491         __u8            __unused;
492         __u8            meta_len;
493         __u8            nr_frags;
494         __u8            tx_flags;
495         unsigned short  gso_size;
496         /* Warning: this field is not always filled in (UFO)! */
497         unsigned short  gso_segs;
498         struct sk_buff  *frag_list;
499         struct skb_shared_hwtstamps hwtstamps;
500         unsigned int    gso_type;
501         u32             tskey;
502 
503         /*
504          * Warning : all fields before dataref are cleared in __alloc_skb()
505          */
506         atomic_t        dataref;
507 
508         /* Intermediate layers must ensure that destructor_arg
509          * remains valid until skb destructor */
510         void *          destructor_arg;
511 
512         /* must be last field, see pskb_expand_head() */
513         skb_frag_t      frags[MAX_SKB_FRAGS];
514 };
515 
516 /* We divide dataref into two halves.  The higher 16 bits hold references
517  * to the payload part of skb->data.  The lower 16 bits hold references to
518  * the entire skb->data.  A clone of a headerless skb holds the length of
519  * the header in skb->hdr_len.
520  *
521  * All users must obey the rule that the skb->data reference count must be
522  * greater than or equal to the payload reference count.
523  *
524  * Holding a reference to the payload part means that the user does not
525  * care about modifications to the header part of skb->data.
526  */
527 #define SKB_DATAREF_SHIFT 16
528 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
529 
530 
531 enum {
532         SKB_FCLONE_UNAVAILABLE, /* skb has no fclone (from head_cache) */
533         SKB_FCLONE_ORIG,        /* orig skb (from fclone_cache) */
534         SKB_FCLONE_CLONE,       /* companion fclone skb (from fclone_cache) */
535 };
536 
537 enum {
538         SKB_GSO_TCPV4 = 1 << 0,
539 
540         /* This indicates the skb is from an untrusted source. */
541         SKB_GSO_DODGY = 1 << 1,
542 
543         /* This indicates the tcp segment has CWR set. */
544         SKB_GSO_TCP_ECN = 1 << 2,
545 
546         SKB_GSO_TCP_FIXEDID = 1 << 3,
547 
548         SKB_GSO_TCPV6 = 1 << 4,
549 
550         SKB_GSO_FCOE = 1 << 5,
551 
552         SKB_GSO_GRE = 1 << 6,
553 
554         SKB_GSO_GRE_CSUM = 1 << 7,
555 
556         SKB_GSO_IPXIP4 = 1 << 8,
557 
558         SKB_GSO_IPXIP6 = 1 << 9,
559 
560         SKB_GSO_UDP_TUNNEL = 1 << 10,
561 
562         SKB_GSO_UDP_TUNNEL_CSUM = 1 << 11,
563 
564         SKB_GSO_PARTIAL = 1 << 12,
565 
566         SKB_GSO_TUNNEL_REMCSUM = 1 << 13,
567 
568         SKB_GSO_SCTP = 1 << 14,
569 
570         SKB_GSO_ESP = 1 << 15,
571 
572         SKB_GSO_UDP = 1 << 16,
573 };
574 
575 #if BITS_PER_LONG > 32
576 #define NET_SKBUFF_DATA_USES_OFFSET 1
577 #endif
578 
579 #ifdef NET_SKBUFF_DATA_USES_OFFSET
580 typedef unsigned int sk_buff_data_t;
581 #else
582 typedef unsigned char *sk_buff_data_t;
583 #endif
584 
585 /** 
586  *      struct sk_buff - socket buffer
587  *      @next: Next buffer in list
588  *      @prev: Previous buffer in list
589  *      @tstamp: Time we arrived/left
590  *      @rbnode: RB tree node, alternative to next/prev for netem/tcp
591  *      @sk: Socket we are owned by
592  *      @dev: Device we arrived on/are leaving by
593  *      @cb: Control buffer. Free for use by every layer. Put private vars here
594  *      @_skb_refdst: destination entry (with norefcount bit)
595  *      @sp: the security path, used for xfrm
596  *      @len: Length of actual data
597  *      @data_len: Data length
598  *      @mac_len: Length of link layer header
599  *      @hdr_len: writable header length of cloned skb
600  *      @csum: Checksum (must include start/offset pair)
601  *      @csum_start: Offset from skb->head where checksumming should start
602  *      @csum_offset: Offset from csum_start where checksum should be stored
603  *      @priority: Packet queueing priority
604  *      @ignore_df: allow local fragmentation
605  *      @cloned: Head may be cloned (check refcnt to be sure)
606  *      @ip_summed: Driver fed us an IP checksum
607  *      @nohdr: Payload reference only, must not modify header
608  *      @pkt_type: Packet class
609  *      @fclone: skbuff clone status
610  *      @ipvs_property: skbuff is owned by ipvs
611  *      @tc_skip_classify: do not classify packet. set by IFB device
612  *      @tc_at_ingress: used within tc_classify to distinguish in/egress
613  *      @tc_redirected: packet was redirected by a tc action
614  *      @tc_from_ingress: if tc_redirected, tc_at_ingress at time of redirect
615  *      @peeked: this packet has been seen already, so stats have been
616  *              done for it, don't do them again
617  *      @nf_trace: netfilter packet trace flag
618  *      @protocol: Packet protocol from driver
619  *      @destructor: Destruct function
620  *      @tcp_tsorted_anchor: list structure for TCP (tp->tsorted_sent_queue)
621  *      @_nfct: Associated connection, if any (with nfctinfo bits)
622  *      @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
623  *      @skb_iif: ifindex of device we arrived on
624  *      @tc_index: Traffic control index
625  *      @hash: the packet hash
626  *      @queue_mapping: Queue mapping for multiqueue devices
627  *      @xmit_more: More SKBs are pending for this queue
628  *      @ndisc_nodetype: router type (from link layer)
629  *      @ooo_okay: allow the mapping of a socket to a queue to be changed
630  *      @l4_hash: indicate hash is a canonical 4-tuple hash over transport
631  *              ports.
632  *      @sw_hash: indicates hash was computed in software stack
633  *      @wifi_acked_valid: wifi_acked was set
634  *      @wifi_acked: whether frame was acked on wifi or not
635  *      @no_fcs:  Request NIC to treat last 4 bytes as Ethernet FCS
636  *      @csum_not_inet: use CRC32c to resolve CHECKSUM_PARTIAL
637  *      @dst_pending_confirm: need to confirm neighbour
638   *     @napi_id: id of the NAPI struct this skb came from
639  *      @secmark: security marking
640  *      @mark: Generic packet mark
641  *      @vlan_proto: vlan encapsulation protocol
642  *      @vlan_tci: vlan tag control information
643  *      @inner_protocol: Protocol (encapsulation)
644  *      @inner_transport_header: Inner transport layer header (encapsulation)
645  *      @inner_network_header: Network layer header (encapsulation)
646  *      @inner_mac_header: Link layer header (encapsulation)
647  *      @transport_header: Transport layer header
648  *      @network_header: Network layer header
649  *      @mac_header: Link layer header
650  *      @tail: Tail pointer
651  *      @end: End pointer
652  *      @head: Head of buffer
653  *      @data: Data head pointer
654  *      @truesize: Buffer size
655  *      @users: User count - see {datagram,tcp}.c
656  */
657 
658 struct sk_buff {
659         union {
660                 struct {
661                         /* These two members must be first. */
662                         struct sk_buff          *next;
663                         struct sk_buff          *prev;
664 
665                         union {
666                                 struct net_device       *dev;
667                                 /* Some protocols might use this space to store information,
668                                  * while device pointer would be NULL.
669                                  * UDP receive path is one user.
670                                  */
671                                 unsigned long           dev_scratch;
672                         };
673                 };
674                 struct rb_node  rbnode; /* used in netem & tcp stack */
675         };
676         struct sock             *sk;
677 
678         union {
679                 ktime_t         tstamp;
680                 u64             skb_mstamp;
681         };
682         /*
683          * This is the control buffer. It is free to use for every
684          * layer. Please put your private variables there. If you
685          * want to keep them across layers you have to do a skb_clone()
686          * first. This is owned by whoever has the skb queued ATM.
687          */
688         char                    cb[48] __aligned(8);
689 
690         union {
691                 struct {
692                         unsigned long   _skb_refdst;
693                         void            (*destructor)(struct sk_buff *skb);
694                 };
695                 struct list_head        tcp_tsorted_anchor;
696         };
697 
698 #ifdef CONFIG_XFRM
699         struct  sec_path        *sp;
700 #endif
701 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
702         unsigned long            _nfct;
703 #endif
704 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
705         struct nf_bridge_info   *nf_bridge;
706 #endif
707         unsigned int            len,
708                                 data_len;
709         __u16                   mac_len,
710                                 hdr_len;
711 
712         /* Following fields are _not_ copied in __copy_skb_header()
713          * Note that queue_mapping is here mostly to fill a hole.
714          */
715         __u16                   queue_mapping;
716 
717 /* if you move cloned around you also must adapt those constants */
718 #ifdef __BIG_ENDIAN_BITFIELD
719 #define CLONED_MASK     (1 << 7)
720 #else
721 #define CLONED_MASK     1
722 #endif
723 #define CLONED_OFFSET()         offsetof(struct sk_buff, __cloned_offset)
724 
725         __u8                    __cloned_offset[0];
726         __u8                    cloned:1,
727                                 nohdr:1,
728                                 fclone:2,
729                                 peeked:1,
730                                 head_frag:1,
731                                 xmit_more:1,
732                                 __unused:1; /* one bit hole */
733 
734         /* fields enclosed in headers_start/headers_end are copied
735          * using a single memcpy() in __copy_skb_header()
736          */
737         /* private: */
738         __u32                   headers_start[0];
739         /* public: */
740 
741 /* if you move pkt_type around you also must adapt those constants */
742 #ifdef __BIG_ENDIAN_BITFIELD
743 #define PKT_TYPE_MAX    (7 << 5)
744 #else
745 #define PKT_TYPE_MAX    7
746 #endif
747 #define PKT_TYPE_OFFSET()       offsetof(struct sk_buff, __pkt_type_offset)
748 
749         __u8                    __pkt_type_offset[0];
750         __u8                    pkt_type:3;
751         __u8                    pfmemalloc:1;
752         __u8                    ignore_df:1;
753 
754         __u8                    nf_trace:1;
755         __u8                    ip_summed:2;
756         __u8                    ooo_okay:1;
757         __u8                    l4_hash:1;
758         __u8                    sw_hash:1;
759         __u8                    wifi_acked_valid:1;
760         __u8                    wifi_acked:1;
761 
762         __u8                    no_fcs:1;
763         /* Indicates the inner headers are valid in the skbuff. */
764         __u8                    encapsulation:1;
765         __u8                    encap_hdr_csum:1;
766         __u8                    csum_valid:1;
767         __u8                    csum_complete_sw:1;
768         __u8                    csum_level:2;
769         __u8                    csum_not_inet:1;
770 
771         __u8                    dst_pending_confirm:1;
772 #ifdef CONFIG_IPV6_NDISC_NODETYPE
773         __u8                    ndisc_nodetype:2;
774 #endif
775         __u8                    ipvs_property:1;
776         __u8                    inner_protocol_type:1;
777         __u8                    remcsum_offload:1;
778 #ifdef CONFIG_NET_SWITCHDEV
779         __u8                    offload_fwd_mark:1;
780         __u8                    offload_mr_fwd_mark:1;
781 #endif
782 #ifdef CONFIG_NET_CLS_ACT
783         __u8                    tc_skip_classify:1;
784         __u8                    tc_at_ingress:1;
785         __u8                    tc_redirected:1;
786         __u8                    tc_from_ingress:1;
787 #endif
788 
789 #ifdef CONFIG_NET_SCHED
790         __u16                   tc_index;       /* traffic control index */
791 #endif
792 
793         union {
794                 __wsum          csum;
795                 struct {
796                         __u16   csum_start;
797                         __u16   csum_offset;
798                 };
799         };
800         __u32                   priority;
801         int                     skb_iif;
802         __u32                   hash;
803         __be16                  vlan_proto;
804         __u16                   vlan_tci;
805 #if defined(CONFIG_NET_RX_BUSY_POLL) || defined(CONFIG_XPS)
806         union {
807                 unsigned int    napi_id;
808                 unsigned int    sender_cpu;
809         };
810 #endif
811 #ifdef CONFIG_NETWORK_SECMARK
812         __u32           secmark;
813 #endif
814 
815         union {
816                 __u32           mark;
817                 __u32           reserved_tailroom;
818         };
819 
820         union {
821                 __be16          inner_protocol;
822                 __u8            inner_ipproto;
823         };
824 
825         __u16                   inner_transport_header;
826         __u16                   inner_network_header;
827         __u16                   inner_mac_header;
828 
829         __be16                  protocol;
830         __u16                   transport_header;
831         __u16                   network_header;
832         __u16                   mac_header;
833 
834         /* private: */
835         __u32                   headers_end[0];
836         /* public: */
837 
838         /* These elements must be at the end, see alloc_skb() for details.  */
839         sk_buff_data_t          tail;
840         sk_buff_data_t          end;
841         unsigned char           *head,
842                                 *data;
843         unsigned int            truesize;
844         refcount_t              users;
845 };
846 
847 #ifdef __KERNEL__
848 /*
849  *      Handling routines are only of interest to the kernel
850  */
851 #include <linux/slab.h>
852 
853 
854 #define SKB_ALLOC_FCLONE        0x01
855 #define SKB_ALLOC_RX            0x02
856 #define SKB_ALLOC_NAPI          0x04
857 
858 /* Returns true if the skb was allocated from PFMEMALLOC reserves */
859 static inline bool skb_pfmemalloc(const struct sk_buff *skb)
860 {
861         return unlikely(skb->pfmemalloc);
862 }
863 
864 /*
865  * skb might have a dst pointer attached, refcounted or not.
866  * _skb_refdst low order bit is set if refcount was _not_ taken
867  */
868 #define SKB_DST_NOREF   1UL
869 #define SKB_DST_PTRMASK ~(SKB_DST_NOREF)
870 
871 #define SKB_NFCT_PTRMASK        ~(7UL)
872 /**
873  * skb_dst - returns skb dst_entry
874  * @skb: buffer
875  *
876  * Returns skb dst_entry, regardless of reference taken or not.
877  */
878 static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
879 {
880         /* If refdst was not refcounted, check we still are in a 
881          * rcu_read_lock section
882          */
883         WARN_ON((skb->_skb_refdst & SKB_DST_NOREF) &&
884                 !rcu_read_lock_held() &&
885                 !rcu_read_lock_bh_held());
886         return (struct dst_entry *)(skb->_skb_refdst & SKB_DST_PTRMASK);
887 }
888 
889 /**
890  * skb_dst_set - sets skb dst
891  * @skb: buffer
892  * @dst: dst entry
893  *
894  * Sets skb dst, assuming a reference was taken on dst and should
895  * be released by skb_dst_drop()
896  */
897 static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
898 {
899         skb->_skb_refdst = (unsigned long)dst;
900 }
901 
902 /**
903  * skb_dst_set_noref - sets skb dst, hopefully, without taking reference
904  * @skb: buffer
905  * @dst: dst entry
906  *
907  * Sets skb dst, assuming a reference was not taken on dst.
908  * If dst entry is cached, we do not take reference and dst_release
909  * will be avoided by refdst_drop. If dst entry is not cached, we take
910  * reference, so that last dst_release can destroy the dst immediately.
911  */
912 static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
913 {
914         WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
915         skb->_skb_refdst = (unsigned long)dst | SKB_DST_NOREF;
916 }
917 
918 /**
919  * skb_dst_is_noref - Test if skb dst isn't refcounted
920  * @skb: buffer
921  */
922 static inline bool skb_dst_is_noref(const struct sk_buff *skb)
923 {
924         return (skb->_skb_refdst & SKB_DST_NOREF) && skb_dst(skb);
925 }
926 
927 static inline struct rtable *skb_rtable(const struct sk_buff *skb)
928 {
929         return (struct rtable *)skb_dst(skb);
930 }
931 
932 /* For mangling skb->pkt_type from user space side from applications
933  * such as nft, tc, etc, we only allow a conservative subset of
934  * possible pkt_types to be set.
935 */
936 static inline bool skb_pkt_type_ok(u32 ptype)
937 {
938         return ptype <= PACKET_OTHERHOST;
939 }
940 
941 static inline unsigned int skb_napi_id(const struct sk_buff *skb)
942 {
943 #ifdef CONFIG_NET_RX_BUSY_POLL
944         return skb->napi_id;
945 #else
946         return 0;
947 #endif
948 }
949 
950 /* decrement the reference count and return true if we can free the skb */
951 static inline bool skb_unref(struct sk_buff *skb)
952 {
953         if (unlikely(!skb))
954                 return false;
955         if (likely(refcount_read(&skb->users) == 1))
956                 smp_rmb();
957         else if (likely(!refcount_dec_and_test(&skb->users)))
958                 return false;
959 
960         return true;
961 }
962 
963 void skb_release_head_state(struct sk_buff *skb);
964 void kfree_skb(struct sk_buff *skb);
965 void kfree_skb_list(struct sk_buff *segs);
966 void skb_tx_error(struct sk_buff *skb);
967 void consume_skb(struct sk_buff *skb);
968 void __consume_stateless_skb(struct sk_buff *skb);
969 void  __kfree_skb(struct sk_buff *skb);
970 extern struct kmem_cache *skbuff_head_cache;
971 
972 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen);
973 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
974                       bool *fragstolen, int *delta_truesize);
975 
976 struct sk_buff *__alloc_skb(unsigned int size, gfp_t priority, int flags,
977                             int node);
978 struct sk_buff *__build_skb(void *data, unsigned int frag_size);
979 struct sk_buff *build_skb(void *data, unsigned int frag_size);
980 static inline struct sk_buff *alloc_skb(unsigned int size,
981                                         gfp_t priority)
982 {
983         return __alloc_skb(size, priority, 0, NUMA_NO_NODE);
984 }
985 
986 struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
987                                      unsigned long data_len,
988                                      int max_page_order,
989                                      int *errcode,
990                                      gfp_t gfp_mask);
991 
992 /* Layout of fast clones : [skb1][skb2][fclone_ref] */
993 struct sk_buff_fclones {
994         struct sk_buff  skb1;
995 
996         struct sk_buff  skb2;
997 
998         refcount_t      fclone_ref;
999 };
1000 
1001 /**
1002  *      skb_fclone_busy - check if fclone is busy
1003  *      @sk: socket
1004  *      @skb: buffer
1005  *
1006  * Returns true if skb is a fast clone, and its clone is not freed.
1007  * Some drivers call skb_orphan() in their ndo_start_xmit(),
1008  * so we also check that this didnt happen.
1009  */
1010 static inline bool skb_fclone_busy(const struct sock *sk,
1011                                    const struct sk_buff *skb)
1012 {
1013         const struct sk_buff_fclones *fclones;
1014 
1015         fclones = container_of(skb, struct sk_buff_fclones, skb1);
1016 
1017         return skb->fclone == SKB_FCLONE_ORIG &&
1018                refcount_read(&fclones->fclone_ref) > 1 &&
1019                fclones->skb2.sk == sk;
1020 }
1021 
1022 static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
1023                                                gfp_t priority)
1024 {
1025         return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
1026 }
1027 
1028 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
1029 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask);
1030 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t priority);
1031 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t priority);
1032 struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
1033                                    gfp_t gfp_mask, bool fclone);
1034 static inline struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom,
1035                                           gfp_t gfp_mask)
1036 {
1037         return __pskb_copy_fclone(skb, headroom, gfp_mask, false);
1038 }
1039 
1040 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, gfp_t gfp_mask);
1041 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
1042                                      unsigned int headroom);
1043 struct sk_buff *skb_copy_expand(const struct sk_buff *skb, int newheadroom,
1044                                 int newtailroom, gfp_t priority);
1045 int __must_check skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
1046                                      int offset, int len);
1047 int __must_check skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg,
1048                               int offset, int len);
1049 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer);
1050 int __skb_pad(struct sk_buff *skb, int pad, bool free_on_error);
1051 
1052 /**
1053  *      skb_pad                 -       zero pad the tail of an skb
1054  *      @skb: buffer to pad
1055  *      @pad: space to pad
1056  *
1057  *      Ensure that a buffer is followed by a padding area that is zero
1058  *      filled. Used by network drivers which may DMA or transfer data
1059  *      beyond the buffer end onto the wire.
1060  *
1061  *      May return error in out of memory cases. The skb is freed on error.
1062  */
1063 static inline int skb_pad(struct sk_buff *skb, int pad)
1064 {
1065         return __skb_pad(skb, pad, true);
1066 }
1067 #define dev_kfree_skb(a)        consume_skb(a)
1068 
1069 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
1070                             int getfrag(void *from, char *to, int offset,
1071                                         int len, int odd, struct sk_buff *skb),
1072                             void *from, int length);
1073 
1074 int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
1075                          int offset, size_t size);
1076 
1077 struct skb_seq_state {
1078         __u32           lower_offset;
1079         __u32           upper_offset;
1080         __u32           frag_idx;
1081         __u32           stepped_offset;
1082         struct sk_buff  *root_skb;
1083         struct sk_buff  *cur_skb;
1084         __u8            *frag_data;
1085 };
1086 
1087 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
1088                           unsigned int to, struct skb_seq_state *st);
1089 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
1090                           struct skb_seq_state *st);
1091 void skb_abort_seq_read(struct skb_seq_state *st);
1092 
1093 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
1094                            unsigned int to, struct ts_config *config);
1095 
1096 /*
1097  * Packet hash types specify the type of hash in skb_set_hash.
1098  *
1099  * Hash types refer to the protocol layer addresses which are used to
1100  * construct a packet's hash. The hashes are used to differentiate or identify
1101  * flows of the protocol layer for the hash type. Hash types are either
1102  * layer-2 (L2), layer-3 (L3), or layer-4 (L4).
1103  *
1104  * Properties of hashes:
1105  *
1106  * 1) Two packets in different flows have different hash values
1107  * 2) Two packets in the same flow should have the same hash value
1108  *
1109  * A hash at a higher layer is considered to be more specific. A driver should
1110  * set the most specific hash possible.
1111  *
1112  * A driver cannot indicate a more specific hash than the layer at which a hash
1113  * was computed. For instance an L3 hash cannot be set as an L4 hash.
1114  *
1115  * A driver may indicate a hash level which is less specific than the
1116  * actual layer the hash was computed on. For instance, a hash computed
1117  * at L4 may be considered an L3 hash. This should only be done if the
1118  * driver can't unambiguously determine that the HW computed the hash at
1119  * the higher layer. Note that the "should" in the second property above
1120  * permits this.
1121  */
1122 enum pkt_hash_types {
1123         PKT_HASH_TYPE_NONE,     /* Undefined type */
1124         PKT_HASH_TYPE_L2,       /* Input: src_MAC, dest_MAC */
1125         PKT_HASH_TYPE_L3,       /* Input: src_IP, dst_IP */
1126         PKT_HASH_TYPE_L4,       /* Input: src_IP, dst_IP, src_port, dst_port */
1127 };
1128 
1129 static inline void skb_clear_hash(struct sk_buff *skb)
1130 {
1131         skb->hash = 0;
1132         skb->sw_hash = 0;
1133         skb->l4_hash = 0;
1134 }
1135 
1136 static inline void skb_clear_hash_if_not_l4(struct sk_buff *skb)
1137 {
1138         if (!skb->l4_hash)
1139                 skb_clear_hash(skb);
1140 }
1141 
1142 static inline void
1143 __skb_set_hash(struct sk_buff *skb, __u32 hash, bool is_sw, bool is_l4)
1144 {
1145         skb->l4_hash = is_l4;
1146         skb->sw_hash = is_sw;
1147         skb->hash = hash;
1148 }
1149 
1150 static inline void
1151 skb_set_hash(struct sk_buff *skb, __u32 hash, enum pkt_hash_types type)
1152 {
1153         /* Used by drivers to set hash from HW */
1154         __skb_set_hash(skb, hash, false, type == PKT_HASH_TYPE_L4);
1155 }
1156 
1157 static inline void
1158 __skb_set_sw_hash(struct sk_buff *skb, __u32 hash, bool is_l4)
1159 {
1160         __skb_set_hash(skb, hash, true, is_l4);
1161 }
1162 
1163 void __skb_get_hash(struct sk_buff *skb);
1164 u32 __skb_get_hash_symmetric(const struct sk_buff *skb);
1165 u32 skb_get_poff(const struct sk_buff *skb);
1166 u32 __skb_get_poff(const struct sk_buff *skb, void *data,
1167                    const struct flow_keys *keys, int hlen);
1168 __be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto,
1169                             void *data, int hlen_proto);
1170 
1171 static inline __be32 skb_flow_get_ports(const struct sk_buff *skb,
1172                                         int thoff, u8 ip_proto)
1173 {
1174         return __skb_flow_get_ports(skb, thoff, ip_proto, NULL, 0);
1175 }
1176 
1177 void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
1178                              const struct flow_dissector_key *key,
1179                              unsigned int key_count);
1180 
1181 bool __skb_flow_dissect(const struct sk_buff *skb,
1182                         struct flow_dissector *flow_dissector,
1183                         void *target_container,
1184                         void *data, __be16 proto, int nhoff, int hlen,
1185                         unsigned int flags);
1186 
1187 static inline bool skb_flow_dissect(const struct sk_buff *skb,
1188                                     struct flow_dissector *flow_dissector,
1189                                     void *target_container, unsigned int flags)
1190 {
1191         return __skb_flow_dissect(skb, flow_dissector, target_container,
1192                                   NULL, 0, 0, 0, flags);
1193 }
1194 
1195 static inline bool skb_flow_dissect_flow_keys(const struct sk_buff *skb,
1196                                               struct flow_keys *flow,
1197                                               unsigned int flags)
1198 {
1199         memset(flow, 0, sizeof(*flow));
1200         return __skb_flow_dissect(skb, &flow_keys_dissector, flow,
1201                                   NULL, 0, 0, 0, flags);
1202 }
1203 
1204 static inline bool skb_flow_dissect_flow_keys_buf(struct flow_keys *flow,
1205                                                   void *data, __be16 proto,
1206                                                   int nhoff, int hlen,
1207                                                   unsigned int flags)
1208 {
1209         memset(flow, 0, sizeof(*flow));
1210         return __skb_flow_dissect(NULL, &flow_keys_buf_dissector, flow,
1211                                   data, proto, nhoff, hlen, flags);
1212 }
1213 
1214 static inline __u32 skb_get_hash(struct sk_buff *skb)
1215 {
1216         if (!skb->l4_hash && !skb->sw_hash)
1217                 __skb_get_hash(skb);
1218 
1219         return skb->hash;
1220 }
1221 
1222 static inline __u32 skb_get_hash_flowi6(struct sk_buff *skb, const struct flowi6 *fl6)
1223 {
1224         if (!skb->l4_hash && !skb->sw_hash) {
1225                 struct flow_keys keys;
1226                 __u32 hash = __get_hash_from_flowi6(fl6, &keys);
1227 
1228                 __skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys));
1229         }
1230 
1231         return skb->hash;
1232 }
1233 
1234 __u32 skb_get_hash_perturb(const struct sk_buff *skb, u32 perturb);
1235 
1236 static inline __u32 skb_get_hash_raw(const struct sk_buff *skb)
1237 {
1238         return skb->hash;
1239 }
1240 
1241 static inline void skb_copy_hash(struct sk_buff *to, const struct sk_buff *from)
1242 {
1243         to->hash = from->hash;
1244         to->sw_hash = from->sw_hash;
1245         to->l4_hash = from->l4_hash;
1246 };
1247 
1248 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1249 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
1250 {
1251         return skb->head + skb->end;
1252 }
1253 
1254 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
1255 {
1256         return skb->end;
1257 }
1258 #else
1259 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
1260 {
1261         return skb->end;
1262 }
1263 
1264 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
1265 {
1266         return skb->end - skb->head;
1267 }
1268 #endif
1269 
1270 /* Internal */
1271 #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
1272 
1273 static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
1274 {
1275         return &skb_shinfo(skb)->hwtstamps;
1276 }
1277 
1278 static inline struct ubuf_info *skb_zcopy(struct sk_buff *skb)
1279 {
1280         bool is_zcopy = skb && skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY;
1281 
1282         return is_zcopy ? skb_uarg(skb) : NULL;
1283 }
1284 
1285 static inline void skb_zcopy_set(struct sk_buff *skb, struct ubuf_info *uarg)
1286 {
1287         if (skb && uarg && !skb_zcopy(skb)) {
1288                 sock_zerocopy_get(uarg);
1289                 skb_shinfo(skb)->destructor_arg = uarg;
1290                 skb_shinfo(skb)->tx_flags |= SKBTX_ZEROCOPY_FRAG;
1291         }
1292 }
1293 
1294 /* Release a reference on a zerocopy structure */
1295 static inline void skb_zcopy_clear(struct sk_buff *skb, bool zerocopy)
1296 {
1297         struct ubuf_info *uarg = skb_zcopy(skb);
1298 
1299         if (uarg) {
1300                 if (uarg->callback == sock_zerocopy_callback) {
1301                         uarg->zerocopy = uarg->zerocopy && zerocopy;
1302                         sock_zerocopy_put(uarg);
1303                 } else {
1304                         uarg->callback(uarg, zerocopy);
1305                 }
1306 
1307                 skb_shinfo(skb)->tx_flags &= ~SKBTX_ZEROCOPY_FRAG;
1308         }
1309 }
1310 
1311 /* Abort a zerocopy operation and revert zckey on error in send syscall */
1312 static inline void skb_zcopy_abort(struct sk_buff *skb)
1313 {
1314         struct ubuf_info *uarg = skb_zcopy(skb);
1315 
1316         if (uarg) {
1317                 sock_zerocopy_put_abort(uarg);
1318                 skb_shinfo(skb)->tx_flags &= ~SKBTX_ZEROCOPY_FRAG;
1319         }
1320 }
1321 
1322 /**
1323  *      skb_queue_empty - check if a queue is empty
1324  *      @list: queue head
1325  *
1326  *      Returns true if the queue is empty, false otherwise.
1327  */
1328 static inline int skb_queue_empty(const struct sk_buff_head *list)
1329 {
1330         return list->next == (const struct sk_buff *) list;
1331 }
1332 
1333 /**
1334  *      skb_queue_is_last - check if skb is the last entry in the queue
1335  *      @list: queue head
1336  *      @skb: buffer
1337  *
1338  *      Returns true if @skb is the last buffer on the list.
1339  */
1340 static inline bool skb_queue_is_last(const struct sk_buff_head *list,
1341                                      const struct sk_buff *skb)
1342 {
1343         return skb->next == (const struct sk_buff *) list;
1344 }
1345 
1346 /**
1347  *      skb_queue_is_first - check if skb is the first entry in the queue
1348  *      @list: queue head
1349  *      @skb: buffer
1350  *
1351  *      Returns true if @skb is the first buffer on the list.
1352  */
1353 static inline bool skb_queue_is_first(const struct sk_buff_head *list,
1354                                       const struct sk_buff *skb)
1355 {
1356         return skb->prev == (const struct sk_buff *) list;
1357 }
1358 
1359 /**
1360  *      skb_queue_next - return the next packet in the queue
1361  *      @list: queue head
1362  *      @skb: current buffer
1363  *
1364  *      Return the next packet in @list after @skb.  It is only valid to
1365  *      call this if skb_queue_is_last() evaluates to false.
1366  */
1367 static inline struct sk_buff *skb_queue_next(const struct sk_buff_head *list,
1368                                              const struct sk_buff *skb)
1369 {
1370         /* This BUG_ON may seem severe, but if we just return then we
1371          * are going to dereference garbage.
1372          */
1373         BUG_ON(skb_queue_is_last(list, skb));
1374         return skb->next;
1375 }
1376 
1377 /**
1378  *      skb_queue_prev - return the prev packet in the queue
1379  *      @list: queue head
1380  *      @skb: current buffer
1381  *
1382  *      Return the prev packet in @list before @skb.  It is only valid to
1383  *      call this if skb_queue_is_first() evaluates to false.
1384  */
1385 static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
1386                                              const struct sk_buff *skb)
1387 {
1388         /* This BUG_ON may seem severe, but if we just return then we
1389          * are going to dereference garbage.
1390          */
1391         BUG_ON(skb_queue_is_first(list, skb));
1392         return skb->prev;
1393 }
1394 
1395 /**
1396  *      skb_get - reference buffer
1397  *      @skb: buffer to reference
1398  *
1399  *      Makes another reference to a socket buffer and returns a pointer
1400  *      to the buffer.
1401  */
1402 static inline struct sk_buff *skb_get(struct sk_buff *skb)
1403 {
1404         refcount_inc(&skb->users);
1405         return skb;
1406 }
1407 
1408 /*
1409  * If users == 1, we are the only owner and can avoid redundant atomic changes.
1410  */
1411 
1412 /**
1413  *      skb_cloned - is the buffer a clone
1414  *      @skb: buffer to check
1415  *
1416  *      Returns true if the buffer was generated with skb_clone() and is
1417  *      one of multiple shared copies of the buffer. Cloned buffers are
1418  *      shared data so must not be written to under normal circumstances.
1419  */
1420 static inline int skb_cloned(const struct sk_buff *skb)
1421 {
1422         return skb->cloned &&
1423                (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
1424 }
1425 
1426 static inline int skb_unclone(struct sk_buff *skb, gfp_t pri)
1427 {
1428         might_sleep_if(gfpflags_allow_blocking(pri));
1429 
1430         if (skb_cloned(skb))
1431                 return pskb_expand_head(skb, 0, 0, pri);
1432 
1433         return 0;
1434 }
1435 
1436 /**
1437  *      skb_header_cloned - is the header a clone
1438  *      @skb: buffer to check
1439  *
1440  *      Returns true if modifying the header part of the buffer requires
1441  *      the data to be copied.
1442  */
1443 static inline int skb_header_cloned(const struct sk_buff *skb)
1444 {
1445         int dataref;
1446 
1447         if (!skb->cloned)
1448                 return 0;
1449 
1450         dataref = atomic_read(&skb_shinfo(skb)->dataref);
1451         dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
1452         return dataref != 1;
1453 }
1454 
1455 static inline int skb_header_unclone(struct sk_buff *skb, gfp_t pri)
1456 {
1457         might_sleep_if(gfpflags_allow_blocking(pri));
1458 
1459         if (skb_header_cloned(skb))
1460                 return pskb_expand_head(skb, 0, 0, pri);
1461 
1462         return 0;
1463 }
1464 
1465 /**
1466  *      __skb_header_release - release reference to header
1467  *      @skb: buffer to operate on
1468  */
1469 static inline void __skb_header_release(struct sk_buff *skb)
1470 {
1471         skb->nohdr = 1;
1472         atomic_set(&skb_shinfo(skb)->dataref, 1 + (1 << SKB_DATAREF_SHIFT));
1473 }
1474 
1475 
1476 /**
1477  *      skb_shared - is the buffer shared
1478  *      @skb: buffer to check
1479  *
1480  *      Returns true if more than one person has a reference to this
1481  *      buffer.
1482  */
1483 static inline int skb_shared(const struct sk_buff *skb)
1484 {
1485         return refcount_read(&skb->users) != 1;
1486 }
1487 
1488 /**
1489  *      skb_share_check - check if buffer is shared and if so clone it
1490  *      @skb: buffer to check
1491  *      @pri: priority for memory allocation
1492  *
1493  *      If the buffer is shared the buffer is cloned and the old copy
1494  *      drops a reference. A new clone with a single reference is returned.
1495  *      If the buffer is not shared the original buffer is returned. When
1496  *      being called from interrupt status or with spinlocks held pri must
1497  *      be GFP_ATOMIC.
1498  *
1499  *      NULL is returned on a memory allocation failure.
1500  */
1501 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, gfp_t pri)
1502 {
1503         might_sleep_if(gfpflags_allow_blocking(pri));
1504         if (skb_shared(skb)) {
1505                 struct sk_buff *nskb = skb_clone(skb, pri);
1506 
1507                 if (likely(nskb))
1508                         consume_skb(skb);
1509                 else
1510                         kfree_skb(skb);
1511                 skb = nskb;
1512         }
1513         return skb;
1514 }
1515 
1516 /*
1517  *      Copy shared buffers into a new sk_buff. We effectively do COW on
1518  *      packets to handle cases where we have a local reader and forward
1519  *      and a couple of other messy ones. The normal one is tcpdumping
1520  *      a packet thats being forwarded.
1521  */
1522 
1523 /**
1524  *      skb_unshare - make a copy of a shared buffer
1525  *      @skb: buffer to check
1526  *      @pri: priority for memory allocation
1527  *
1528  *      If the socket buffer is a clone then this function creates a new
1529  *      copy of the data, drops a reference count on the old copy and returns
1530  *      the new copy with the reference count at 1. If the buffer is not a clone
1531  *      the original buffer is returned. When called with a spinlock held or
1532  *      from interrupt state @pri must be %GFP_ATOMIC
1533  *
1534  *      %NULL is returned on a memory allocation failure.
1535  */
1536 static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
1537                                           gfp_t pri)
1538 {
1539         might_sleep_if(gfpflags_allow_blocking(pri));
1540         if (skb_cloned(skb)) {
1541                 struct sk_buff *nskb = skb_copy(skb, pri);
1542 
1543                 /* Free our shared copy */
1544                 if (likely(nskb))
1545                         consume_skb(skb);
1546                 else
1547                         kfree_skb(skb);
1548                 skb = nskb;
1549         }
1550         return skb;
1551 }
1552 
1553 /**
1554  *      skb_peek - peek at the head of an &sk_buff_head
1555  *      @list_: list to peek at
1556  *
1557  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1558  *      be careful with this one. A peek leaves the buffer on the
1559  *      list and someone else may run off with it. You must hold
1560  *      the appropriate locks or have a private queue to do this.
1561  *
1562  *      Returns %NULL for an empty list or a pointer to the head element.
1563  *      The reference count is not incremented and the reference is therefore
1564  *      volatile. Use with caution.
1565  */
1566 static inline struct sk_buff *skb_peek(const struct sk_buff_head *list_)
1567 {
1568         struct sk_buff *skb = list_->next;
1569 
1570         if (skb == (struct sk_buff *)list_)
1571                 skb = NULL;
1572         return skb;
1573 }
1574 
1575 /**
1576  *      skb_peek_next - peek skb following the given one from a queue
1577  *      @skb: skb to start from
1578  *      @list_: list to peek at
1579  *
1580  *      Returns %NULL when the end of the list is met or a pointer to the
1581  *      next element. The reference count is not incremented and the
1582  *      reference is therefore volatile. Use with caution.
1583  */
1584 static inline struct sk_buff *skb_peek_next(struct sk_buff *skb,
1585                 const struct sk_buff_head *list_)
1586 {
1587         struct sk_buff *next = skb->next;
1588 
1589         if (next == (struct sk_buff *)list_)
1590                 next = NULL;
1591         return next;
1592 }
1593 
1594 /**
1595  *      skb_peek_tail - peek at the tail of an &sk_buff_head
1596  *      @list_: list to peek at
1597  *
1598  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1599  *      be careful with this one. A peek leaves the buffer on the
1600  *      list and someone else may run off with it. You must hold
1601  *      the appropriate locks or have a private queue to do this.
1602  *
1603  *      Returns %NULL for an empty list or a pointer to the tail element.
1604  *      The reference count is not incremented and the reference is therefore
1605  *      volatile. Use with caution.
1606  */
1607 static inline struct sk_buff *skb_peek_tail(const struct sk_buff_head *list_)
1608 {
1609         struct sk_buff *skb = list_->prev;
1610 
1611         if (skb == (struct sk_buff *)list_)
1612                 skb = NULL;
1613         return skb;
1614 
1615 }
1616 
1617 /**
1618  *      skb_queue_len   - get queue length
1619  *      @list_: list to measure
1620  *
1621  *      Return the length of an &sk_buff queue.
1622  */
1623 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
1624 {
1625         return list_->qlen;
1626 }
1627 
1628 /**
1629  *      __skb_queue_head_init - initialize non-spinlock portions of sk_buff_head
1630  *      @list: queue to initialize
1631  *
1632  *      This initializes only the list and queue length aspects of
1633  *      an sk_buff_head object.  This allows to initialize the list
1634  *      aspects of an sk_buff_head without reinitializing things like
1635  *      the spinlock.  It can also be used for on-stack sk_buff_head
1636  *      objects where the spinlock is known to not be used.
1637  */
1638 static inline void __skb_queue_head_init(struct sk_buff_head *list)
1639 {
1640         list->prev = list->next = (struct sk_buff *)list;
1641         list->qlen = 0;
1642 }
1643 
1644 /*
1645  * This function creates a split out lock class for each invocation;
1646  * this is needed for now since a whole lot of users of the skb-queue
1647  * infrastructure in drivers have different locking usage (in hardirq)
1648  * than the networking core (in softirq only). In the long run either the
1649  * network layer or drivers should need annotation to consolidate the
1650  * main types of usage into 3 classes.
1651  */
1652 static inline void skb_queue_head_init(struct sk_buff_head *list)
1653 {
1654         spin_lock_init(&list->lock);
1655         __skb_queue_head_init(list);
1656 }
1657 
1658 static inline void skb_queue_head_init_class(struct sk_buff_head *list,
1659                 struct lock_class_key *class)
1660 {
1661         skb_queue_head_init(list);
1662         lockdep_set_class(&list->lock, class);
1663 }
1664 
1665 /*
1666  *      Insert an sk_buff on a list.
1667  *
1668  *      The "__skb_xxxx()" functions are the non-atomic ones that
1669  *      can only be called with interrupts disabled.
1670  */
1671 void skb_insert(struct sk_buff *old, struct sk_buff *newsk,
1672                 struct sk_buff_head *list);
1673 static inline void __skb_insert(struct sk_buff *newsk,
1674                                 struct sk_buff *prev, struct sk_buff *next,
1675                                 struct sk_buff_head *list)
1676 {
1677         newsk->next = next;
1678         newsk->prev = prev;
1679         next->prev  = prev->next = newsk;
1680         list->qlen++;
1681 }
1682 
1683 static inline void __skb_queue_splice(const struct sk_buff_head *list,
1684                                       struct sk_buff *prev,
1685                                       struct sk_buff *next)
1686 {
1687         struct sk_buff *first = list->next;
1688         struct sk_buff *last = list->prev;
1689 
1690         first->prev = prev;
1691         prev->next = first;
1692 
1693         last->next = next;
1694         next->prev = last;
1695 }
1696 
1697 /**
1698  *      skb_queue_splice - join two skb lists, this is designed for stacks
1699  *      @list: the new list to add
1700  *      @head: the place to add it in the first list
1701  */
1702 static inline void skb_queue_splice(const struct sk_buff_head *list,
1703                                     struct sk_buff_head *head)
1704 {
1705         if (!skb_queue_empty(list)) {
1706                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1707                 head->qlen += list->qlen;
1708         }
1709 }
1710 
1711 /**
1712  *      skb_queue_splice_init - join two skb lists and reinitialise the emptied list
1713  *      @list: the new list to add
1714  *      @head: the place to add it in the first list
1715  *
1716  *      The list at @list is reinitialised
1717  */
1718 static inline void skb_queue_splice_init(struct sk_buff_head *list,
1719                                          struct sk_buff_head *head)
1720 {
1721         if (!skb_queue_empty(list)) {
1722                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1723                 head->qlen += list->qlen;
1724                 __skb_queue_head_init(list);
1725         }
1726 }
1727 
1728 /**
1729  *      skb_queue_splice_tail - join two skb lists, each list being a queue
1730  *      @list: the new list to add
1731  *      @head: the place to add it in the first list
1732  */
1733 static inline void skb_queue_splice_tail(const struct sk_buff_head *list,
1734                                          struct sk_buff_head *head)
1735 {
1736         if (!skb_queue_empty(list)) {
1737                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1738                 head->qlen += list->qlen;
1739         }
1740 }
1741 
1742 /**
1743  *      skb_queue_splice_tail_init - join two skb lists and reinitialise the emptied list
1744  *      @list: the new list to add
1745  *      @head: the place to add it in the first list
1746  *
1747  *      Each of the lists is a queue.
1748  *      The list at @list is reinitialised
1749  */
1750 static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
1751                                               struct sk_buff_head *head)
1752 {
1753         if (!skb_queue_empty(list)) {
1754                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1755                 head->qlen += list->qlen;
1756                 __skb_queue_head_init(list);
1757         }
1758 }
1759 
1760 /**
1761  *      __skb_queue_after - queue a buffer at the list head
1762  *      @list: list to use
1763  *      @prev: place after this buffer
1764  *      @newsk: buffer to queue
1765  *
1766  *      Queue a buffer int the middle of a list. This function takes no locks
1767  *      and you must therefore hold required locks before calling it.
1768  *
1769  *      A buffer cannot be placed on two lists at the same time.
1770  */
1771 static inline void __skb_queue_after(struct sk_buff_head *list,
1772                                      struct sk_buff *prev,
1773                                      struct sk_buff *newsk)
1774 {
1775         __skb_insert(newsk, prev, prev->next, list);
1776 }
1777 
1778 void skb_append(struct sk_buff *old, struct sk_buff *newsk,
1779                 struct sk_buff_head *list);
1780 
1781 static inline void __skb_queue_before(struct sk_buff_head *list,
1782                                       struct sk_buff *next,
1783                                       struct sk_buff *newsk)
1784 {
1785         __skb_insert(newsk, next->prev, next, list);
1786 }
1787 
1788 /**
1789  *      __skb_queue_head - queue a buffer at the list head
1790  *      @list: list to use
1791  *      @newsk: buffer to queue
1792  *
1793  *      Queue a buffer at the start of a list. This function takes no locks
1794  *      and you must therefore hold required locks before calling it.
1795  *
1796  *      A buffer cannot be placed on two lists at the same time.
1797  */
1798 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
1799 static inline void __skb_queue_head(struct sk_buff_head *list,
1800                                     struct sk_buff *newsk)
1801 {
1802         __skb_queue_after(list, (struct sk_buff *)list, newsk);
1803 }
1804 
1805 /**
1806  *      __skb_queue_tail - queue a buffer at the list tail
1807  *      @list: list to use
1808  *      @newsk: buffer to queue
1809  *
1810  *      Queue a buffer at the end of a list. This function takes no locks
1811  *      and you must therefore hold required locks before calling it.
1812  *
1813  *      A buffer cannot be placed on two lists at the same time.
1814  */
1815 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
1816 static inline void __skb_queue_tail(struct sk_buff_head *list,
1817                                    struct sk_buff *newsk)
1818 {
1819         __skb_queue_before(list, (struct sk_buff *)list, newsk);
1820 }
1821 
1822 /*
1823  * remove sk_buff from list. _Must_ be called atomically, and with
1824  * the list known..
1825  */
1826 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
1827 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1828 {
1829         struct sk_buff *next, *prev;
1830 
1831         list->qlen--;
1832         next       = skb->next;
1833         prev       = skb->prev;
1834         skb->next  = skb->prev = NULL;
1835         next->prev = prev;
1836         prev->next = next;
1837 }
1838 
1839 /**
1840  *      __skb_dequeue - remove from the head of the queue
1841  *      @list: list to dequeue from
1842  *
1843  *      Remove the head of the list. This function does not take any locks
1844  *      so must be used with appropriate locks held only. The head item is
1845  *      returned or %NULL if the list is empty.
1846  */
1847 struct sk_buff *skb_dequeue(struct sk_buff_head *list);
1848 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
1849 {
1850         struct sk_buff *skb = skb_peek(list);
1851         if (skb)
1852                 __skb_unlink(skb, list);
1853         return skb;
1854 }
1855 
1856 /**
1857  *      __skb_dequeue_tail - remove from the tail of the queue
1858  *      @list: list to dequeue from
1859  *
1860  *      Remove the tail of the list. This function does not take any locks
1861  *      so must be used with appropriate locks held only. The tail item is
1862  *      returned or %NULL if the list is empty.
1863  */
1864 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
1865 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
1866 {
1867         struct sk_buff *skb = skb_peek_tail(list);
1868         if (skb)
1869                 __skb_unlink(skb, list);
1870         return skb;
1871 }
1872 
1873 
1874 static inline bool skb_is_nonlinear(const struct sk_buff *skb)
1875 {
1876         return skb->data_len;
1877 }
1878 
1879 static inline unsigned int skb_headlen(const struct sk_buff *skb)
1880 {
1881         return skb->len - skb->data_len;
1882 }
1883 
1884 static inline unsigned int __skb_pagelen(const struct sk_buff *skb)
1885 {
1886         unsigned int i, len = 0;
1887 
1888         for (i = skb_shinfo(skb)->nr_frags - 1; (int)i >= 0; i--)
1889                 len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
1890         return len;
1891 }
1892 
1893 static inline unsigned int skb_pagelen(const struct sk_buff *skb)
1894 {
1895         return skb_headlen(skb) + __skb_pagelen(skb);
1896 }
1897 
1898 /**
1899  * __skb_fill_page_desc - initialise a paged fragment in an skb
1900  * @skb: buffer containing fragment to be initialised
1901  * @i: paged fragment index to initialise
1902  * @page: the page to use for this fragment
1903  * @off: the offset to the data with @page
1904  * @size: the length of the data
1905  *
1906  * Initialises the @i'th fragment of @skb to point to &size bytes at
1907  * offset @off within @page.
1908  *
1909  * Does not take any additional reference on the fragment.
1910  */
1911 static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
1912                                         struct page *page, int off, int size)
1913 {
1914         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1915 
1916         /*
1917          * Propagate page pfmemalloc to the skb if we can. The problem is
1918          * that not all callers have unique ownership of the page but rely
1919          * on page_is_pfmemalloc doing the right thing(tm).
1920          */
1921         frag->page.p              = page;
1922         frag->page_offset         = off;
1923         skb_frag_size_set(frag, size);
1924 
1925         page = compound_head(page);
1926         if (page_is_pfmemalloc(page))
1927                 skb->pfmemalloc = true;
1928 }
1929 
1930 /**
1931  * skb_fill_page_desc - initialise a paged fragment in an skb
1932  * @skb: buffer containing fragment to be initialised
1933  * @i: paged fragment index to initialise
1934  * @page: the page to use for this fragment
1935  * @off: the offset to the data with @page
1936  * @size: the length of the data
1937  *
1938  * As per __skb_fill_page_desc() -- initialises the @i'th fragment of
1939  * @skb to point to @size bytes at offset @off within @page. In
1940  * addition updates @skb such that @i is the last fragment.
1941  *
1942  * Does not take any additional reference on the fragment.
1943  */
1944 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
1945                                       struct page *page, int off, int size)
1946 {
1947         __skb_fill_page_desc(skb, i, page, off, size);
1948         skb_shinfo(skb)->nr_frags = i + 1;
1949 }
1950 
1951 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
1952                      int size, unsigned int truesize);
1953 
1954 void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
1955                           unsigned int truesize);
1956 
1957 #define SKB_PAGE_ASSERT(skb)    BUG_ON(skb_shinfo(skb)->nr_frags)
1958 #define SKB_FRAG_ASSERT(skb)    BUG_ON(skb_has_frag_list(skb))
1959 #define SKB_LINEAR_ASSERT(skb)  BUG_ON(skb_is_nonlinear(skb))
1960 
1961 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1962 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1963 {
1964         return skb->head + skb->tail;
1965 }
1966 
1967 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1968 {
1969         skb->tail = skb->data - skb->head;
1970 }
1971 
1972 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1973 {
1974         skb_reset_tail_pointer(skb);
1975         skb->tail += offset;
1976 }
1977 
1978 #else /* NET_SKBUFF_DATA_USES_OFFSET */
1979 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1980 {
1981         return skb->tail;
1982 }
1983 
1984 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1985 {
1986         skb->tail = skb->data;
1987 }
1988 
1989 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1990 {
1991         skb->tail = skb->data + offset;
1992 }
1993 
1994 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
1995 
1996 /*
1997  *      Add data to an sk_buff
1998  */
1999 void *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len);
2000 void *skb_put(struct sk_buff *skb, unsigned int len);
2001 static inline void *__skb_put(struct sk_buff *skb, unsigned int len)
2002 {
2003         void *tmp = skb_tail_pointer(skb);
2004         SKB_LINEAR_ASSERT(skb);
2005         skb->tail += len;
2006         skb->len  += len;
2007         return tmp;
2008 }
2009 
2010 static inline void *__skb_put_zero(struct sk_buff *skb, unsigned int len)
2011 {
2012         void *tmp = __skb_put(skb, len);
2013 
2014         memset(tmp, 0, len);
2015         return tmp;
2016 }
2017 
2018 static inline void *__skb_put_data(struct sk_buff *skb, const void *data,
2019                                    unsigned int len)
2020 {
2021         void *tmp = __skb_put(skb, len);
2022 
2023         memcpy(tmp, data, len);
2024         return tmp;
2025 }
2026 
2027 static inline void __skb_put_u8(struct sk_buff *skb, u8 val)
2028 {
2029         *(u8 *)__skb_put(skb, 1) = val;
2030 }
2031 
2032 static inline void *skb_put_zero(struct sk_buff *skb, unsigned int len)
2033 {
2034         void *tmp = skb_put(skb, len);
2035 
2036         memset(tmp, 0, len);
2037 
2038         return tmp;
2039 }
2040 
2041 static inline void *skb_put_data(struct sk_buff *skb, const void *data,
2042                                  unsigned int len)
2043 {
2044         void *tmp = skb_put(skb, len);
2045 
2046         memcpy(tmp, data, len);
2047 
2048         return tmp;
2049 }
2050 
2051 static inline void skb_put_u8(struct sk_buff *skb, u8 val)
2052 {
2053         *(u8 *)skb_put(skb, 1) = val;
2054 }
2055 
2056 void *skb_push(struct sk_buff *skb, unsigned int len);
2057 static inline void *__skb_push(struct sk_buff *skb, unsigned int len)
2058 {
2059         skb->data -= len;
2060         skb->len  += len;
2061         return skb->data;
2062 }
2063 
2064 void *skb_pull(struct sk_buff *skb, unsigned int len);
2065 static inline void *__skb_pull(struct sk_buff *skb, unsigned int len)
2066 {
2067         skb->len -= len;
2068         BUG_ON(skb->len < skb->data_len);
2069         return skb->data += len;
2070 }
2071 
2072 static inline void *skb_pull_inline(struct sk_buff *skb, unsigned int len)
2073 {
2074         return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
2075 }
2076 
2077 void *__pskb_pull_tail(struct sk_buff *skb, int delta);
2078 
2079 static inline void *__pskb_pull(struct sk_buff *skb, unsigned int len)
2080 {
2081         if (len > skb_headlen(skb) &&
2082             !__pskb_pull_tail(skb, len - skb_headlen(skb)))
2083                 return NULL;
2084         skb->len -= len;
2085         return skb->data += len;
2086 }
2087 
2088 static inline void *pskb_pull(struct sk_buff *skb, unsigned int len)
2089 {
2090         return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
2091 }
2092 
2093 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
2094 {
2095         if (likely(len <= skb_headlen(skb)))
2096                 return 1;
2097         if (unlikely(len > skb->len))
2098                 return 0;
2099         return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
2100 }
2101 
2102 void skb_condense(struct sk_buff *skb);
2103 
2104 /**
2105  *      skb_headroom - bytes at buffer head
2106  *      @skb: buffer to check
2107  *
2108  *      Return the number of bytes of free space at the head of an &sk_buff.
2109  */
2110 static inline unsigned int skb_headroom(const struct sk_buff *skb)
2111 {
2112         return skb->data - skb->head;
2113 }
2114 
2115 /**
2116  *      skb_tailroom - bytes at buffer end
2117  *      @skb: buffer to check
2118  *
2119  *      Return the number of bytes of free space at the tail of an sk_buff
2120  */
2121 static inline int skb_tailroom(const struct sk_buff *skb)
2122 {
2123         return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
2124 }
2125 
2126 /**
2127  *      skb_availroom - bytes at buffer end
2128  *      @skb: buffer to check
2129  *
2130  *      Return the number of bytes of free space at the tail of an sk_buff
2131  *      allocated by sk_stream_alloc()
2132  */
2133 static inline int skb_availroom(const struct sk_buff *skb)
2134 {
2135         if (skb_is_nonlinear(skb))
2136                 return 0;
2137 
2138         return skb->end - skb->tail - skb->reserved_tailroom;
2139 }
2140 
2141 /**
2142  *      skb_reserve - adjust headroom
2143  *      @skb: buffer to alter
2144  *      @len: bytes to move
2145  *
2146  *      Increase the headroom of an empty &sk_buff by reducing the tail
2147  *      room. This is only allowed for an empty buffer.
2148  */
2149 static inline void skb_reserve(struct sk_buff *skb, int len)
2150 {
2151         skb->data += len;
2152         skb->tail += len;
2153 }
2154 
2155 /**
2156  *      skb_tailroom_reserve - adjust reserved_tailroom
2157  *      @skb: buffer to alter
2158  *      @mtu: maximum amount of headlen permitted
2159  *      @needed_tailroom: minimum amount of reserved_tailroom
2160  *
2161  *      Set reserved_tailroom so that headlen can be as large as possible but
2162  *      not larger than mtu and tailroom cannot be smaller than
2163  *      needed_tailroom.
2164  *      The required headroom should already have been reserved before using
2165  *      this function.
2166  */
2167 static inline void skb_tailroom_reserve(struct sk_buff *skb, unsigned int mtu,
2168                                         unsigned int needed_tailroom)
2169 {
2170         SKB_LINEAR_ASSERT(skb);
2171         if (mtu < skb_tailroom(skb) - needed_tailroom)
2172                 /* use at most mtu */
2173                 skb->reserved_tailroom = skb_tailroom(skb) - mtu;
2174         else
2175                 /* use up to all available space */
2176                 skb->reserved_tailroom = needed_tailroom;
2177 }
2178 
2179 #define ENCAP_TYPE_ETHER        0
2180 #define ENCAP_TYPE_IPPROTO      1
2181 
2182 static inline void skb_set_inner_protocol(struct sk_buff *skb,
2183                                           __be16 protocol)
2184 {
2185         skb->inner_protocol = protocol;
2186         skb->inner_protocol_type = ENCAP_TYPE_ETHER;
2187 }
2188 
2189 static inline void skb_set_inner_ipproto(struct sk_buff *skb,
2190                                          __u8 ipproto)
2191 {
2192         skb->inner_ipproto = ipproto;
2193         skb->inner_protocol_type = ENCAP_TYPE_IPPROTO;
2194 }
2195 
2196 static inline void skb_reset_inner_headers(struct sk_buff *skb)
2197 {
2198         skb->inner_mac_header = skb->mac_header;
2199         skb->inner_network_header = skb->network_header;
2200         skb->inner_transport_header = skb->transport_header;
2201 }
2202 
2203 static inline void skb_reset_mac_len(struct sk_buff *skb)
2204 {
2205         skb->mac_len = skb->network_header - skb->mac_header;
2206 }
2207 
2208 static inline unsigned char *skb_inner_transport_header(const struct sk_buff
2209                                                         *skb)
2210 {
2211         return skb->head + skb->inner_transport_header;
2212 }
2213 
2214 static inline int skb_inner_transport_offset(const struct sk_buff *skb)
2215 {
2216         return skb_inner_transport_header(skb) - skb->data;
2217 }
2218 
2219 static inline void skb_reset_inner_transport_header(struct sk_buff *skb)
2220 {
2221         skb->inner_transport_header = skb->data - skb->head;
2222 }
2223 
2224 static inline void skb_set_inner_transport_header(struct sk_buff *skb,
2225                                                    const int offset)
2226 {
2227         skb_reset_inner_transport_header(skb);
2228         skb->inner_transport_header += offset;
2229 }
2230 
2231 static inline unsigned char *skb_inner_network_header(const struct sk_buff *skb)
2232 {
2233         return skb->head + skb->inner_network_header;
2234 }
2235 
2236 static inline void skb_reset_inner_network_header(struct sk_buff *skb)
2237 {
2238         skb->inner_network_header = skb->data - skb->head;
2239 }
2240 
2241 static inline void skb_set_inner_network_header(struct sk_buff *skb,
2242                                                 const int offset)
2243 {
2244         skb_reset_inner_network_header(skb);
2245         skb->inner_network_header += offset;
2246 }
2247 
2248 static inline unsigned char *skb_inner_mac_header(const struct sk_buff *skb)
2249 {
2250         return skb->head + skb->inner_mac_header;
2251 }
2252 
2253 static inline void skb_reset_inner_mac_header(struct sk_buff *skb)
2254 {
2255         skb->inner_mac_header = skb->data - skb->head;
2256 }
2257 
2258 static inline void skb_set_inner_mac_header(struct sk_buff *skb,
2259                                             const int offset)
2260 {
2261         skb_reset_inner_mac_header(skb);
2262         skb->inner_mac_header += offset;
2263 }
2264 static inline bool skb_transport_header_was_set(const struct sk_buff *skb)
2265 {
2266         return skb->transport_header != (typeof(skb->transport_header))~0U;
2267 }
2268 
2269 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
2270 {
2271         return skb->head + skb->transport_header;
2272 }
2273 
2274 static inline void skb_reset_transport_header(struct sk_buff *skb)
2275 {
2276         skb->transport_header = skb->data - skb->head;
2277 }
2278 
2279 static inline void skb_set_transport_header(struct sk_buff *skb,
2280                                             const int offset)
2281 {
2282         skb_reset_transport_header(skb);
2283         skb->transport_header += offset;
2284 }
2285 
2286 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
2287 {
2288         return skb->head + skb->network_header;
2289 }
2290 
2291 static inline void skb_reset_network_header(struct sk_buff *skb)
2292 {
2293         skb->network_header = skb->data - skb->head;
2294 }
2295 
2296 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
2297 {
2298         skb_reset_network_header(skb);
2299         skb->network_header += offset;
2300 }
2301 
2302 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
2303 {
2304         return skb->head + skb->mac_header;
2305 }
2306 
2307 static inline int skb_mac_offset(const struct sk_buff *skb)
2308 {
2309         return skb_mac_header(skb) - skb->data;
2310 }
2311 
2312 static inline u32 skb_mac_header_len(const struct sk_buff *skb)
2313 {
2314         return skb->network_header - skb->mac_header;
2315 }
2316 
2317 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
2318 {
2319         return skb->mac_header != (typeof(skb->mac_header))~0U;
2320 }
2321 
2322 static inline void skb_reset_mac_header(struct sk_buff *skb)
2323 {
2324         skb->mac_header = skb->data - skb->head;
2325 }
2326 
2327 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
2328 {
2329         skb_reset_mac_header(skb);
2330         skb->mac_header += offset;
2331 }
2332 
2333 static inline void skb_pop_mac_header(struct sk_buff *skb)
2334 {
2335         skb->mac_header = skb->network_header;
2336 }
2337 
2338 static inline void skb_probe_transport_header(struct sk_buff *skb,
2339                                               const int offset_hint)
2340 {
2341         struct flow_keys keys;
2342 
2343         if (skb_transport_header_was_set(skb))
2344                 return;
2345         else if (skb_flow_dissect_flow_keys(skb, &keys, 0))
2346                 skb_set_transport_header(skb, keys.control.thoff);
2347         else
2348                 skb_set_transport_header(skb, offset_hint);
2349 }
2350 
2351 static inline void skb_mac_header_rebuild(struct sk_buff *skb)
2352 {
2353         if (skb_mac_header_was_set(skb)) {
2354                 const unsigned char *old_mac = skb_mac_header(skb);
2355 
2356                 skb_set_mac_header(skb, -skb->mac_len);
2357                 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
2358         }
2359 }
2360 
2361 static inline int skb_checksum_start_offset(const struct sk_buff *skb)
2362 {
2363         return skb->csum_start - skb_headroom(skb);
2364 }
2365 
2366 static inline unsigned char *skb_checksum_start(const struct sk_buff *skb)
2367 {
2368         return skb->head + skb->csum_start;
2369 }
2370 
2371 static inline int skb_transport_offset(const struct sk_buff *skb)
2372 {
2373         return skb_transport_header(skb) - skb->data;
2374 }
2375 
2376 static inline u32 skb_network_header_len(const struct sk_buff *skb)
2377 {
2378         return skb->transport_header - skb->network_header;
2379 }
2380 
2381 static inline u32 skb_inner_network_header_len(const struct sk_buff *skb)
2382 {
2383         return skb->inner_transport_header - skb->inner_network_header;
2384 }
2385 
2386 static inline int skb_network_offset(const struct sk_buff *skb)
2387 {
2388         return skb_network_header(skb) - skb->data;
2389 }
2390 
2391 static inline int skb_inner_network_offset(const struct sk_buff *skb)
2392 {
2393         return skb_inner_network_header(skb) - skb->data;
2394 }
2395 
2396 static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
2397 {
2398         return pskb_may_pull(skb, skb_network_offset(skb) + len);
2399 }
2400 
2401 /*
2402  * CPUs often take a performance hit when accessing unaligned memory
2403  * locations. The actual performance hit varies, it can be small if the
2404  * hardware handles it or large if we have to take an exception and fix it
2405  * in software.
2406  *
2407  * Since an ethernet header is 14 bytes network drivers often end up with
2408  * the IP header at an unaligned offset. The IP header can be aligned by
2409  * shifting the start of the packet by 2 bytes. Drivers should do this
2410  * with:
2411  *
2412  * skb_reserve(skb, NET_IP_ALIGN);
2413  *
2414  * The downside to this alignment of the IP header is that the DMA is now
2415  * unaligned. On some architectures the cost of an unaligned DMA is high
2416  * and this cost outweighs the gains made by aligning the IP header.
2417  *
2418  * Since this trade off varies between architectures, we allow NET_IP_ALIGN
2419  * to be overridden.
2420  */
2421 #ifndef NET_IP_ALIGN
2422 #define NET_IP_ALIGN    2
2423 #endif
2424 
2425 /*
2426  * The networking layer reserves some headroom in skb data (via
2427  * dev_alloc_skb). This is used to avoid having to reallocate skb data when
2428  * the header has to grow. In the default case, if the header has to grow
2429  * 32 bytes or less we avoid the reallocation.
2430  *
2431  * Unfortunately this headroom changes the DMA alignment of the resulting
2432  * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
2433  * on some architectures. An architecture can override this value,
2434  * perhaps setting it to a cacheline in size (since that will maintain
2435  * cacheline alignment of the DMA). It must be a power of 2.
2436  *
2437  * Various parts of the networking layer expect at least 32 bytes of
2438  * headroom, you should not reduce this.
2439  *
2440  * Using max(32, L1_CACHE_BYTES) makes sense (especially with RPS)
2441  * to reduce average number of cache lines per packet.
2442  * get_rps_cpus() for example only access one 64 bytes aligned block :
2443  * NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
2444  */
2445 #ifndef NET_SKB_PAD
2446 #define NET_SKB_PAD     max(32, L1_CACHE_BYTES)
2447 #endif
2448 
2449 int ___pskb_trim(struct sk_buff *skb, unsigned int len);
2450 
2451 static inline void __skb_set_length(struct sk_buff *skb, unsigned int len)
2452 {
2453         if (unlikely(skb_is_nonlinear(skb))) {
2454                 WARN_ON(1);
2455                 return;
2456         }
2457         skb->len = len;
2458         skb_set_tail_pointer(skb, len);
2459 }
2460 
2461 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
2462 {
2463         __skb_set_length(skb, len);
2464 }
2465 
2466 void skb_trim(struct sk_buff *skb, unsigned int len);
2467 
2468 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
2469 {
2470         if (skb->data_len)
2471                 return ___pskb_trim(skb, len);
2472         __skb_trim(skb, len);
2473         return 0;
2474 }
2475 
2476 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
2477 {
2478         return (len < skb->len) ? __pskb_trim(skb, len) : 0;
2479 }
2480 
2481 /**
2482  *      pskb_trim_unique - remove end from a paged unique (not cloned) buffer
2483  *      @skb: buffer to alter
2484  *      @len: new length
2485  *
2486  *      This is identical to pskb_trim except that the caller knows that
2487  *      the skb is not cloned so we should never get an error due to out-
2488  *      of-memory.
2489  */
2490 static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
2491 {
2492         int err = pskb_trim(skb, len);
2493         BUG_ON(err);
2494 }
2495 
2496 static inline int __skb_grow(struct sk_buff *skb, unsigned int len)
2497 {
2498         unsigned int diff = len - skb->len;
2499 
2500         if (skb_tailroom(skb) < diff) {
2501                 int ret = pskb_expand_head(skb, 0, diff - skb_tailroom(skb),
2502                                            GFP_ATOMIC);
2503                 if (ret)
2504                         return ret;
2505         }
2506         __skb_set_length(skb, len);
2507         return 0;
2508 }
2509 
2510 /**
2511  *      skb_orphan - orphan a buffer
2512  *      @skb: buffer to orphan
2513  *
2514  *      If a buffer currently has an owner then we call the owner's
2515  *      destructor function and make the @skb unowned. The buffer continues
2516  *      to exist but is no longer charged to its former owner.
2517  */
2518 static inline void skb_orphan(struct sk_buff *skb)
2519 {
2520         if (skb->destructor) {
2521                 skb->destructor(skb);
2522                 skb->destructor = NULL;
2523                 skb->sk         = NULL;
2524         } else {
2525                 BUG_ON(skb->sk);
2526         }
2527 }
2528 
2529 /**
2530  *      skb_orphan_frags - orphan the frags contained in a buffer
2531  *      @skb: buffer to orphan frags from
2532  *      @gfp_mask: allocation mask for replacement pages
2533  *
2534  *      For each frag in the SKB which needs a destructor (i.e. has an
2535  *      owner) create a copy of that frag and release the original
2536  *      page by calling the destructor.
2537  */
2538 static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
2539 {
2540         if (likely(!skb_zcopy(skb)))
2541                 return 0;
2542         if (skb_uarg(skb)->callback == sock_zerocopy_callback)
2543                 return 0;
2544         return skb_copy_ubufs(skb, gfp_mask);
2545 }
2546 
2547 /* Frags must be orphaned, even if refcounted, if skb might loop to rx path */
2548 static inline int skb_orphan_frags_rx(struct sk_buff *skb, gfp_t gfp_mask)
2549 {
2550         if (likely(!skb_zcopy(skb)))
2551                 return 0;
2552         return skb_copy_ubufs(skb, gfp_mask);
2553 }
2554 
2555 /**
2556  *      __skb_queue_purge - empty a list
2557  *      @list: list to empty
2558  *
2559  *      Delete all buffers on an &sk_buff list. Each buffer is removed from
2560  *      the list and one reference dropped. This function does not take the
2561  *      list lock and the caller must hold the relevant locks to use it.
2562  */
2563 void skb_queue_purge(struct sk_buff_head *list);
2564 static inline void __skb_queue_purge(struct sk_buff_head *list)
2565 {
2566         struct sk_buff *skb;
2567         while ((skb = __skb_dequeue(list)) != NULL)
2568                 kfree_skb(skb);
2569 }
2570 
2571 void skb_rbtree_purge(struct rb_root *root);
2572 
2573 void *netdev_alloc_frag(unsigned int fragsz);
2574 
2575 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int length,
2576                                    gfp_t gfp_mask);
2577 
2578 /**
2579  *      netdev_alloc_skb - allocate an skbuff for rx on a specific device
2580  *      @dev: network device to receive on
2581  *      @length: length to allocate
2582  *
2583  *      Allocate a new &sk_buff and assign it a usage count of one. The
2584  *      buffer has unspecified headroom built in. Users should allocate
2585  *      the headroom they think they need without accounting for the
2586  *      built in space. The built in space is used for optimisations.
2587  *
2588  *      %NULL is returned if there is no free memory. Although this function
2589  *      allocates memory it can be called from an interrupt.
2590  */
2591 static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
2592                                                unsigned int length)
2593 {
2594         return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
2595 }
2596 
2597 /* legacy helper around __netdev_alloc_skb() */
2598 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
2599                                               gfp_t gfp_mask)
2600 {
2601         return __netdev_alloc_skb(NULL, length, gfp_mask);
2602 }
2603 
2604 /* legacy helper around netdev_alloc_skb() */
2605 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
2606 {
2607         return netdev_alloc_skb(NULL, length);
2608 }
2609 
2610 
2611 static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
2612                 unsigned int length, gfp_t gfp)
2613 {
2614         struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
2615 
2616         if (NET_IP_ALIGN && skb)
2617                 skb_reserve(skb, NET_IP_ALIGN);
2618         return skb;
2619 }
2620 
2621 static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
2622                 unsigned int length)
2623 {
2624         return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC);
2625 }
2626 
2627 static inline void skb_free_frag(void *addr)
2628 {
2629         page_frag_free(addr);
2630 }
2631 
2632 void *napi_alloc_frag(unsigned int fragsz);
2633 struct sk_buff *__napi_alloc_skb(struct napi_struct *napi,
2634                                  unsigned int length, gfp_t gfp_mask);
2635 static inline struct sk_buff *napi_alloc_skb(struct napi_struct *napi,
2636                                              unsigned int length)
2637 {
2638         return __napi_alloc_skb(napi, length, GFP_ATOMIC);
2639 }
2640 void napi_consume_skb(struct sk_buff *skb, int budget);
2641 
2642 void __kfree_skb_flush(void);
2643 void __kfree_skb_defer(struct sk_buff *skb);
2644 
2645 /**
2646  * __dev_alloc_pages - allocate page for network Rx
2647  * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
2648  * @order: size of the allocation
2649  *
2650  * Allocate a new page.
2651  *
2652  * %NULL is returned if there is no free memory.
2653 */
2654 static inline struct page *__dev_alloc_pages(gfp_t gfp_mask,
2655                                              unsigned int order)
2656 {
2657         /* This piece of code contains several assumptions.
2658          * 1.  This is for device Rx, therefor a cold page is preferred.
2659          * 2.  The expectation is the user wants a compound page.
2660          * 3.  If requesting a order 0 page it will not be compound
2661          *     due to the check to see if order has a value in prep_new_page
2662          * 4.  __GFP_MEMALLOC is ignored if __GFP_NOMEMALLOC is set due to
2663          *     code in gfp_to_alloc_flags that should be enforcing this.
2664          */
2665         gfp_mask |= __GFP_COMP | __GFP_MEMALLOC;
2666 
2667         return alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
2668 }
2669 
2670 static inline struct page *dev_alloc_pages(unsigned int order)
2671 {
2672         return __dev_alloc_pages(GFP_ATOMIC | __GFP_NOWARN, order);
2673 }
2674 
2675 /**
2676  * __dev_alloc_page - allocate a page for network Rx
2677  * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
2678  *
2679  * Allocate a new page.
2680  *
2681  * %NULL is returned if there is no free memory.
2682  */
2683 static inline struct page *__dev_alloc_page(gfp_t gfp_mask)
2684 {
2685         return __dev_alloc_pages(gfp_mask, 0);
2686 }
2687 
2688 static inline struct page *dev_alloc_page(void)
2689 {
2690         return dev_alloc_pages(0);
2691 }
2692 
2693 /**
2694  *      skb_propagate_pfmemalloc - Propagate pfmemalloc if skb is allocated after RX page
2695  *      @page: The page that was allocated from skb_alloc_page
2696  *      @skb: The skb that may need pfmemalloc set
2697  */
2698 static inline void skb_propagate_pfmemalloc(struct page *page,
2699                                              struct sk_buff *skb)
2700 {
2701         if (page_is_pfmemalloc(page))
2702                 skb->pfmemalloc = true;
2703 }
2704 
2705 /**
2706  * skb_frag_page - retrieve the page referred to by a paged fragment
2707  * @frag: the paged fragment
2708  *
2709  * Returns the &struct page associated with @frag.
2710  */
2711 static inline struct page *skb_frag_page(const skb_frag_t *frag)
2712 {
2713         return frag->page.p;
2714 }
2715 
2716 /**
2717  * __skb_frag_ref - take an addition reference on a paged fragment.
2718  * @frag: the paged fragment
2719  *
2720  * Takes an additional reference on the paged fragment @frag.
2721  */
2722 static inline void __skb_frag_ref(skb_frag_t *frag)
2723 {
2724         get_page(skb_frag_page(frag));
2725 }
2726 
2727 /**
2728  * skb_frag_ref - take an addition reference on a paged fragment of an skb.
2729  * @skb: the buffer
2730  * @f: the fragment offset.
2731  *
2732  * Takes an additional reference on the @f'th paged fragment of @skb.
2733  */
2734 static inline void skb_frag_ref(struct sk_buff *skb, int f)
2735 {
2736         __skb_frag_ref(&skb_shinfo(skb)->frags[f]);
2737 }
2738 
2739 /**
2740  * __skb_frag_unref - release a reference on a paged fragment.
2741  * @frag: the paged fragment
2742  *
2743  * Releases a reference on the paged fragment @frag.
2744  */
2745 static inline void __skb_frag_unref(skb_frag_t *frag)
2746 {
2747         put_page(skb_frag_page(frag));
2748 }
2749 
2750 /**
2751  * skb_frag_unref - release a reference on a paged fragment of an skb.
2752  * @skb: the buffer
2753  * @f: the fragment offset
2754  *
2755  * Releases a reference on the @f'th paged fragment of @skb.
2756  */
2757 static inline void skb_frag_unref(struct sk_buff *skb, int f)
2758 {
2759         __skb_frag_unref(&skb_shinfo(skb)->frags[f]);
2760 }
2761 
2762 /**
2763  * skb_frag_address - gets the address of the data contained in a paged fragment
2764  * @frag: the paged fragment buffer
2765  *
2766  * Returns the address of the data within @frag. The page must already
2767  * be mapped.
2768  */
2769 static inline void *skb_frag_address(const skb_frag_t *frag)
2770 {
2771         return page_address(skb_frag_page(frag)) + frag->page_offset;
2772 }
2773 
2774 /**
2775  * skb_frag_address_safe - gets the address of the data contained in a paged fragment
2776  * @frag: the paged fragment buffer
2777  *
2778  * Returns the address of the data within @frag. Checks that the page
2779  * is mapped and returns %NULL otherwise.
2780  */
2781 static inline void *skb_frag_address_safe(const skb_frag_t *frag)
2782 {
2783         void *ptr = page_address(skb_frag_page(frag));
2784         if (unlikely(!ptr))
2785                 return NULL;
2786 
2787         return ptr + frag->page_offset;
2788 }
2789 
2790 /**
2791  * __skb_frag_set_page - sets the page contained in a paged fragment
2792  * @frag: the paged fragment
2793  * @page: the page to set
2794  *
2795  * Sets the fragment @frag to contain @page.
2796  */
2797 static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)
2798 {
2799         frag->page.p = page;
2800 }
2801 
2802 /**
2803  * skb_frag_set_page - sets the page contained in a paged fragment of an skb
2804  * @skb: the buffer
2805  * @f: the fragment offset
2806  * @page: the page to set
2807  *
2808  * Sets the @f'th fragment of @skb to contain @page.
2809  */
2810 static inline void skb_frag_set_page(struct sk_buff *skb, int f,
2811                                      struct page *page)
2812 {
2813         __skb_frag_set_page(&skb_shinfo(skb)->frags[f], page);
2814 }
2815 
2816 bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t prio);
2817 
2818 /**
2819  * skb_frag_dma_map - maps a paged fragment via the DMA API
2820  * @dev: the device to map the fragment to
2821  * @frag: the paged fragment to map
2822  * @offset: the offset within the fragment (starting at the
2823  *          fragment's own offset)
2824  * @size: the number of bytes to map
2825  * @dir: the direction of the mapping (``PCI_DMA_*``)
2826  *
2827  * Maps the page associated with @frag to @device.
2828  */
2829 static inline dma_addr_t skb_frag_dma_map(struct device *dev,
2830                                           const skb_frag_t *frag,
2831                                           size_t offset, size_t size,
2832                                           enum dma_data_direction dir)
2833 {
2834         return dma_map_page(dev, skb_frag_page(frag),
2835                             frag->page_offset + offset, size, dir);
2836 }
2837 
2838 static inline struct sk_buff *pskb_copy(struct sk_buff *skb,
2839                                         gfp_t gfp_mask)
2840 {
2841         return __pskb_copy(skb, skb_headroom(skb), gfp_mask);
2842 }
2843 
2844 
2845 static inline struct sk_buff *pskb_copy_for_clone(struct sk_buff *skb,
2846                                                   gfp_t gfp_mask)
2847 {
2848         return __pskb_copy_fclone(skb, skb_headroom(skb), gfp_mask, true);
2849 }
2850 
2851 
2852 /**
2853  *      skb_clone_writable - is the header of a clone writable
2854  *      @skb: buffer to check
2855  *      @len: length up to which to write
2856  *
2857  *      Returns true if modifying the header part of the cloned buffer
2858  *      does not requires the data to be copied.
2859  */
2860 static inline int skb_clone_writable(const struct sk_buff *skb, unsigned int len)
2861 {
2862         return !skb_header_cloned(skb) &&
2863                skb_headroom(skb) + len <= skb->hdr_len;
2864 }
2865 
2866 static inline int skb_try_make_writable(struct sk_buff *skb,
2867                                         unsigned int write_len)
2868 {
2869         return skb_cloned(skb) && !skb_clone_writable(skb, write_len) &&
2870                pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
2871 }
2872 
2873 static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
2874                             int cloned)
2875 {
2876         int delta = 0;
2877 
2878         if (headroom > skb_headroom(skb))
2879                 delta = headroom - skb_headroom(skb);
2880 
2881         if (delta || cloned)
2882                 return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
2883                                         GFP_ATOMIC);
2884         return 0;
2885 }
2886 
2887 /**
2888  *      skb_cow - copy header of skb when it is required
2889  *      @skb: buffer to cow
2890  *      @headroom: needed headroom
2891  *
2892  *      If the skb passed lacks sufficient headroom or its data part
2893  *      is shared, data is reallocated. If reallocation fails, an error
2894  *      is returned and original skb is not changed.
2895  *
2896  *      The result is skb with writable area skb->head...skb->tail
2897  *      and at least @headroom of space at head.
2898  */
2899 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
2900 {
2901         return __skb_cow(skb, headroom, skb_cloned(skb));
2902 }
2903 
2904 /**
2905  *      skb_cow_head - skb_cow but only making the head writable
2906  *      @skb: buffer to cow
2907  *      @headroom: needed headroom
2908  *
2909  *      This function is identical to skb_cow except that we replace the
2910  *      skb_cloned check by skb_header_cloned.  It should be used when
2911  *      you only need to push on some header and do not need to modify
2912  *      the data.
2913  */
2914 static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
2915 {
2916         return __skb_cow(skb, headroom, skb_header_cloned(skb));
2917 }
2918 
2919 /**
2920  *      skb_padto       - pad an skbuff up to a minimal size
2921  *      @skb: buffer to pad
2922  *      @len: minimal length
2923  *
2924  *      Pads up a buffer to ensure the trailing bytes exist and are
2925  *      blanked. If the buffer already contains sufficient data it
2926  *      is untouched. Otherwise it is extended. Returns zero on
2927  *      success. The skb is freed on error.
2928  */
2929 static inline int skb_padto(struct sk_buff *skb, unsigned int len)
2930 {
2931         unsigned int size = skb->len;
2932         if (likely(size >= len))
2933                 return 0;
2934         return skb_pad(skb, len - size);
2935 }
2936 
2937 /**
2938  *      skb_put_padto - increase size and pad an skbuff up to a minimal size
2939  *      @skb: buffer to pad
2940  *      @len: minimal length
2941  *      @free_on_error: free buffer on error
2942  *
2943  *      Pads up a buffer to ensure the trailing bytes exist and are
2944  *      blanked. If the buffer already contains sufficient data it
2945  *      is untouched. Otherwise it is extended. Returns zero on
2946  *      success. The skb is freed on error if @free_on_error is true.
2947  */
2948 static inline int __skb_put_padto(struct sk_buff *skb, unsigned int len,
2949                                   bool free_on_error)
2950 {
2951         unsigned int size = skb->len;
2952 
2953         if (unlikely(size < len)) {
2954                 len -= size;
2955                 if (__skb_pad(skb, len, free_on_error))
2956                         return -ENOMEM;
2957                 __skb_put(skb, len);
2958         }
2959         return 0;
2960 }
2961 
2962 /**
2963  *      skb_put_padto - increase size and pad an skbuff up to a minimal size
2964  *      @skb: buffer to pad
2965  *      @len: minimal length
2966  *
2967  *      Pads up a buffer to ensure the trailing bytes exist and are
2968  *      blanked. If the buffer already contains sufficient data it
2969  *      is untouched. Otherwise it is extended. Returns zero on
2970  *      success. The skb is freed on error.
2971  */
2972 static inline int skb_put_padto(struct sk_buff *skb, unsigned int len)
2973 {
2974         return __skb_put_padto(skb, len, true);
2975 }
2976 
2977 static inline int skb_add_data(struct sk_buff *skb,
2978                                struct iov_iter *from, int copy)
2979 {
2980         const int off = skb->len;
2981 
2982         if (skb->ip_summed == CHECKSUM_NONE) {
2983                 __wsum csum = 0;
2984                 if (csum_and_copy_from_iter_full(skb_put(skb, copy), copy,
2985                                                  &csum, from)) {
2986                         skb->csum = csum_block_add(skb->csum, csum, off);
2987                         return 0;
2988                 }
2989         } else if (copy_from_iter_full(skb_put(skb, copy), copy, from))
2990                 return 0;
2991 
2992         __skb_trim(skb, off);
2993         return -EFAULT;
2994 }
2995 
2996 static inline bool skb_can_coalesce(struct sk_buff *skb, int i,
2997                                     const struct page *page, int off)
2998 {
2999         if (skb_zcopy(skb))
3000                 return false;
3001         if (i) {
3002                 const struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
3003 
3004                 return page == skb_frag_page(frag) &&
3005                        off == frag->page_offset + skb_frag_size(frag);
3006         }
3007         return false;
3008 }
3009 
3010 static inline int __skb_linearize(struct sk_buff *skb)
3011 {
3012         return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
3013 }
3014 
3015 /**
3016  *      skb_linearize - convert paged skb to linear one
3017  *      @skb: buffer to linarize
3018  *
3019  *      If there is no free memory -ENOMEM is returned, otherwise zero
3020  *      is returned and the old skb data released.
3021  */
3022 static inline int skb_linearize(struct sk_buff *skb)
3023 {
3024         return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
3025 }
3026 
3027 /**
3028  * skb_has_shared_frag - can any frag be overwritten
3029  * @skb: buffer to test
3030  *
3031  * Return true if the skb has at least one frag that might be modified
3032  * by an external entity (as in vmsplice()/sendfile())
3033  */
3034 static inline bool skb_has_shared_frag(const struct sk_buff *skb)
3035 {
3036         return skb_is_nonlinear(skb) &&
3037                skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
3038 }
3039 
3040 /**
3041  *      skb_linearize_cow - make sure skb is linear and writable
3042  *      @skb: buffer to process
3043  *
3044  *      If there is no free memory -ENOMEM is returned, otherwise zero
3045  *      is returned and the old skb data released.
3046  */
3047 static inline int skb_linearize_cow(struct sk_buff *skb)
3048 {
3049         return skb_is_nonlinear(skb) || skb_cloned(skb) ?
3050                __skb_linearize(skb) : 0;
3051 }
3052 
3053 static __always_inline void
3054 __skb_postpull_rcsum(struct sk_buff *skb, const void *start, unsigned int len,
3055                      unsigned int off)
3056 {
3057         if (skb->ip_summed == CHECKSUM_COMPLETE)
3058                 skb->csum = csum_block_sub(skb->csum,
3059                                            csum_partial(start, len, 0), off);
3060         else if (skb->ip_summed == CHECKSUM_PARTIAL &&
3061                  skb_checksum_start_offset(skb) < 0)
3062                 skb->ip_summed = CHECKSUM_NONE;
3063 }
3064 
3065 /**
3066  *      skb_postpull_rcsum - update checksum for received skb after pull
3067  *      @skb: buffer to update
3068  *      @start: start of data before pull
3069  *      @len: length of data pulled
3070  *
3071  *      After doing a pull on a received packet, you need to call this to
3072  *      update the CHECKSUM_COMPLETE checksum, or set ip_summed to
3073  *      CHECKSUM_NONE so that it can be recomputed from scratch.
3074  */
3075 static inline void skb_postpull_rcsum(struct sk_buff *skb,
3076                                       const void *start, unsigned int len)
3077 {
3078         __skb_postpull_rcsum(skb, start, len, 0);
3079 }
3080 
3081 static __always_inline void
3082 __skb_postpush_rcsum(struct sk_buff *skb, const void *start, unsigned int len,
3083                      unsigned int off)
3084 {
3085         if (skb->ip_summed == CHECKSUM_COMPLETE)
3086                 skb->csum = csum_block_add(skb->csum,
3087                                            csum_partial(start, len, 0), off);
3088 }
3089 
3090 /**
3091  *      skb_postpush_rcsum - update checksum for received skb after push
3092  *      @skb: buffer to update
3093  *      @start: start of data after push
3094  *      @len: length of data pushed
3095  *
3096  *      After doing a push on a received packet, you need to call this to
3097  *      update the CHECKSUM_COMPLETE checksum.
3098  */
3099 static inline void skb_postpush_rcsum(struct sk_buff *skb,
3100                                       const void *start, unsigned int len)
3101 {
3102         __skb_postpush_rcsum(skb, start, len, 0);
3103 }
3104 
3105 void *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
3106 
3107 /**
3108  *      skb_push_rcsum - push skb and update receive checksum
3109  *      @skb: buffer to update
3110  *      @len: length of data pulled
3111  *
3112  *      This function performs an skb_push on the packet and updates
3113  *      the CHECKSUM_COMPLETE checksum.  It should be used on
3114  *      receive path processing instead of skb_push unless you know
3115  *      that the checksum difference is zero (e.g., a valid IP header)
3116  *      or you are setting ip_summed to CHECKSUM_NONE.
3117  */
3118 static inline void *skb_push_rcsum(struct sk_buff *skb, unsigned int len)
3119 {
3120         skb_push(skb, len);
3121         skb_postpush_rcsum(skb, skb->data, len);
3122         return skb->data;
3123 }
3124 
3125 /**
3126  *      pskb_trim_rcsum - trim received skb and update checksum
3127  *      @skb: buffer to trim
3128  *      @len: new length
3129  *
3130  *      This is exactly the same as pskb_trim except that it ensures the
3131  *      checksum of received packets are still valid after the operation.
3132  */
3133 
3134 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
3135 {
3136         if (likely(len >= skb->len))
3137                 return 0;
3138         if (skb->ip_summed == CHECKSUM_COMPLETE)
3139                 skb->ip_summed = CHECKSUM_NONE;
3140         return __pskb_trim(skb, len);
3141 }
3142 
3143 static inline int __skb_trim_rcsum(struct sk_buff *skb, unsigned int len)
3144 {
3145         if (skb->ip_summed == CHECKSUM_COMPLETE)
3146                 skb->ip_summed = CHECKSUM_NONE;
3147         __skb_trim(skb, len);
3148         return 0;
3149 }
3150 
3151 static inline int __skb_grow_rcsum(struct sk_buff *skb, unsigned int len)
3152 {
3153         if (skb->ip_summed == CHECKSUM_COMPLETE)
3154                 skb->ip_summed = CHECKSUM_NONE;
3155         return __skb_grow(skb, len);
3156 }
3157 
3158 #define rb_to_skb(rb) rb_entry_safe(rb, struct sk_buff, rbnode)
3159 #define skb_rb_first(root) rb_to_skb(rb_first(root))
3160 #define skb_rb_last(root)  rb_to_skb(rb_last(root))
3161 #define skb_rb_next(skb)   rb_to_skb(rb_next(&(skb)->rbnode))
3162 #define skb_rb_prev(skb)   rb_to_skb(rb_prev(&(skb)->rbnode))
3163 
3164 #define skb_queue_walk(queue, skb) \
3165                 for (skb = (queue)->next;                                       \
3166                      skb != (struct sk_buff *)(queue);                          \
3167                      skb = skb->next)
3168 
3169 #define skb_queue_walk_safe(queue, skb, tmp)                                    \
3170                 for (skb = (queue)->next, tmp = skb->next;                      \
3171                      skb != (struct sk_buff *)(queue);                          \
3172                      skb = tmp, tmp = skb->next)
3173 
3174 #define skb_queue_walk_from(queue, skb)                                         \
3175                 for (; skb != (struct sk_buff *)(queue);                        \
3176                      skb = skb->next)
3177 
3178 #define skb_rbtree_walk(skb, root)                                              \
3179                 for (skb = skb_rb_first(root); skb != NULL;                     \
3180                      skb = skb_rb_next(skb))
3181 
3182 #define skb_rbtree_walk_from(skb)                                               \
3183                 for (; skb != NULL;                                             \
3184                      skb = skb_rb_next(skb))
3185 
3186 #define skb_rbtree_walk_from_safe(skb, tmp)                                     \
3187                 for (; tmp = skb ? skb_rb_next(skb) : NULL, (skb != NULL);      \
3188                      skb = tmp)
3189 
3190 #define skb_queue_walk_from_safe(queue, skb, tmp)                               \
3191                 for (tmp = skb->next;                                           \
3192                      skb != (struct sk_buff *)(queue);                          \
3193                      skb = tmp, tmp = skb->next)
3194 
3195 #define skb_queue_reverse_walk(queue, skb) \
3196                 for (skb = (queue)->prev;                                       \
3197                      skb != (struct sk_buff *)(queue);                          \
3198                      skb = skb->prev)
3199 
3200 #define skb_queue_reverse_walk_safe(queue, skb, tmp)                            \
3201                 for (skb = (queue)->prev, tmp = skb->prev;                      \
3202                      skb != (struct sk_buff *)(queue);                          \
3203                      skb = tmp, tmp = skb->prev)
3204 
3205 #define skb_queue_reverse_walk_from_safe(queue, skb, tmp)                       \
3206                 for (tmp = skb->prev;                                           \
3207                      skb != (struct sk_buff *)(queue);                          \
3208                      skb = tmp, tmp = skb->prev)
3209 
3210 static inline bool skb_has_frag_list(const struct sk_buff *skb)
3211 {
3212         return skb_shinfo(skb)->frag_list != NULL;
3213 }
3214 
3215 static inline void skb_frag_list_init(struct sk_buff *skb)
3216 {
3217         skb_shinfo(skb)->frag_list = NULL;
3218 }
3219 
3220 #define skb_walk_frags(skb, iter)       \
3221         for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
3222 
3223 
3224 int __skb_wait_for_more_packets(struct sock *sk, int *err, long *timeo_p,
3225                                 const struct sk_buff *skb);
3226 struct sk_buff *__skb_try_recv_from_queue(struct sock *sk,
3227                                           struct sk_buff_head *queue,
3228                                           unsigned int flags,
3229                                           void (*destructor)(struct sock *sk,
3230                                                            struct sk_buff *skb),
3231                                           int *peeked, int *off, int *err,
3232                                           struct sk_buff **last);
3233 struct sk_buff *__skb_try_recv_datagram(struct sock *sk, unsigned flags,
3234                                         void (*destructor)(struct sock *sk,
3235                                                            struct sk_buff *skb),
3236                                         int *peeked, int *off, int *err,
3237                                         struct sk_buff **last);
3238 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
3239                                     void (*destructor)(struct sock *sk,
3240                                                        struct sk_buff *skb),
3241                                     int *peeked, int *off, int *err);
3242 struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags, int noblock,
3243                                   int *err);
3244 unsigned int datagram_poll(struct file *file, struct socket *sock,
3245                            struct poll_table_struct *wait);
3246 int skb_copy_datagram_iter(const struct sk_buff *from, int offset,
3247                            struct iov_iter *to, int size);
3248 static inline int skb_copy_datagram_msg(const struct sk_buff *from, int offset,
3249                                         struct msghdr *msg, int size)
3250 {
3251         return skb_copy_datagram_iter(from, offset, &msg->msg_iter, size);
3252 }
3253 int skb_copy_and_csum_datagram_msg(struct sk_buff *skb, int hlen,
3254                                    struct msghdr *msg);
3255 int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
3256                                  struct iov_iter *from, int len);
3257 int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *frm);
3258 void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
3259 void __skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb, int len);
3260 static inline void skb_free_datagram_locked(struct sock *sk,
3261                                             struct sk_buff *skb)
3262 {
3263         __skb_free_datagram_locked(sk, skb, 0);
3264 }
3265 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags);
3266 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len);
3267 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len);
3268 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to,
3269                               int len, __wsum csum);
3270 int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
3271                     struct pipe_inode_info *pipe, unsigned int len,
3272                     unsigned int flags);
3273 int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
3274                          int len);
3275 int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len);
3276 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
3277 unsigned int skb_zerocopy_headlen(const struct sk_buff *from);
3278 int skb_zerocopy(struct sk_buff *to, struct sk_buff *from,
3279                  int len, int hlen);
3280 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len);
3281 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen);
3282 void skb_scrub_packet(struct sk_buff *skb, bool xnet);
3283 unsigned int skb_gso_transport_seglen(const struct sk_buff *skb);
3284 bool skb_gso_validate_mtu(const struct sk_buff *skb, unsigned int mtu);
3285 struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features);
3286 struct sk_buff *skb_vlan_untag(struct sk_buff *skb);
3287 int skb_ensure_writable(struct sk_buff *skb, int write_len);
3288 int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci);
3289 int skb_vlan_pop(struct sk_buff *skb);
3290 int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci);
3291 struct sk_buff *pskb_extract(struct sk_buff *skb, int off, int to_copy,
3292                              gfp_t gfp);
3293 
3294 static inline int memcpy_from_msg(void *data, struct msghdr *msg, int len)
3295 {
3296         return copy_from_iter_full(data, len, &msg->msg_iter) ? 0 : -EFAULT;
3297 }
3298 
3299 static inline int memcpy_to_msg(struct msghdr *msg, void *data, int len)
3300 {
3301         return copy_to_iter(data, len, &msg->msg_iter) == len ? 0 : -EFAULT;
3302 }
3303 
3304 struct skb_checksum_ops {
3305         __wsum (*update)(const void *mem, int len, __wsum wsum);
3306         __wsum (*combine)(__wsum csum, __wsum csum2, int offset, int len);
3307 };
3308 
3309 extern const struct skb_checksum_ops *crc32c_csum_stub __read_mostly;
3310 
3311 __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
3312                       __wsum csum, const struct skb_checksum_ops *ops);
3313 __wsum skb_checksum(const struct sk_buff *skb, int offset, int len,
3314                     __wsum csum);
3315 
3316 static inline void * __must_check
3317 __skb_header_pointer(const struct sk_buff *skb, int offset,
3318                      int len, void *data, int hlen, void *buffer)
3319 {
3320         if (hlen - offset >= len)
3321                 return data + offset;
3322 
3323         if (!skb ||
3324             skb_copy_bits(skb, offset, buffer, len) < 0)
3325                 return NULL;
3326 
3327         return buffer;
3328 }
3329 
3330 static inline void * __must_check
3331 skb_header_pointer(const struct sk_buff *skb, int offset, int len, void *buffer)
3332 {
3333         return __skb_header_pointer(skb, offset, len, skb->data,
3334                                     skb_headlen(skb), buffer);
3335 }
3336 
3337 /**
3338  *      skb_needs_linearize - check if we need to linearize a given skb
3339  *                            depending on the given device features.
3340  *      @skb: socket buffer to check
3341  *      @features: net device features
3342  *
3343  *      Returns true if either:
3344  *      1. skb has frag_list and the device doesn't support FRAGLIST, or
3345  *      2. skb is fragmented and the device does not support SG.
3346  */
3347 static inline bool skb_needs_linearize(struct sk_buff *skb,
3348                                        netdev_features_t features)
3349 {
3350         return skb_is_nonlinear(skb) &&
3351                ((skb_has_frag_list(skb) && !(features & NETIF_F_FRAGLIST)) ||
3352                 (skb_shinfo(skb)->nr_frags && !(features & NETIF_F_SG)));
3353 }
3354 
3355 static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
3356                                              void *to,
3357                                              const unsigned int len)
3358 {
3359         memcpy(to, skb->data, len);
3360 }
3361 
3362 static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
3363                                                     const int offset, void *to,
3364                                                     const unsigned int len)
3365 {
3366         memcpy(to, skb->data + offset, len);
3367 }
3368 
3369 static inline void skb_copy_to_linear_data(struct sk_buff *skb,
3370                                            const void *from,
3371                                            const unsigned int len)
3372 {
3373         memcpy(skb->data, from, len);
3374 }
3375 
3376 static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
3377                                                   const int offset,
3378                                                   const void *from,
3379                                                   const unsigned int len)
3380 {
3381         memcpy(skb->data + offset, from, len);
3382 }
3383 
3384 void skb_init(void);
3385 
3386 static inline ktime_t skb_get_ktime(const struct sk_buff *skb)
3387 {
3388         return skb->tstamp;
3389 }
3390 
3391 /**
3392  *      skb_get_timestamp - get timestamp from a skb
3393  *      @skb: skb to get stamp from
3394  *      @stamp: pointer to struct timeval to store stamp in
3395  *
3396  *      Timestamps are stored in the skb as offsets to a base timestamp.
3397  *      This function converts the offset back to a struct timeval and stores
3398  *      it in stamp.
3399  */
3400 static inline void skb_get_timestamp(const struct sk_buff *skb,
3401                                      struct timeval *stamp)
3402 {
3403         *stamp = ktime_to_timeval(skb->tstamp);
3404 }
3405 
3406 static inline void skb_get_timestampns(const struct sk_buff *skb,
3407                                        struct timespec *stamp)
3408 {
3409         *stamp = ktime_to_timespec(skb->tstamp);
3410 }
3411 
3412 static inline void __net_timestamp(struct sk_buff *skb)
3413 {
3414         skb->tstamp = ktime_get_real();
3415 }
3416 
3417 static inline ktime_t net_timedelta(ktime_t t)
3418 {
3419         return ktime_sub(ktime_get_real(), t);
3420 }
3421 
3422 static inline ktime_t net_invalid_timestamp(void)
3423 {
3424         return 0;
3425 }
3426 
3427 static inline u8 skb_metadata_len(const struct sk_buff *skb)
3428 {
3429         return skb_shinfo(skb)->meta_len;
3430 }
3431 
3432 static inline void *skb_metadata_end(const struct sk_buff *skb)
3433 {
3434         return skb_mac_header(skb);
3435 }
3436 
3437 static inline bool __skb_metadata_differs(const struct sk_buff *skb_a,
3438                                           const struct sk_buff *skb_b,
3439                                           u8 meta_len)
3440 {
3441         const void *a = skb_metadata_end(skb_a);
3442         const void *b = skb_metadata_end(skb_b);
3443         /* Using more efficient varaiant than plain call to memcmp(). */
3444 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
3445         u64 diffs = 0;
3446 
3447         switch (meta_len) {
3448 #define __it(x, op) (x -= sizeof(u##op))
3449 #define __it_diff(a, b, op) (*(u##op *)__it(a, op)) ^ (*(u##op *)__it(b, op))
3450         case 32: diffs |= __it_diff(a, b, 64);
3451         case 24: diffs |= __it_diff(a, b, 64);
3452         case 16: diffs |= __it_diff(a, b, 64);
3453         case  8: diffs |= __it_diff(a, b, 64);
3454                 break;
3455         case 28: diffs |= __it_diff(a, b, 64);
3456         case 20: diffs |= __it_diff(a, b, 64);
3457         case 12: diffs |= __it_diff(a, b, 64);
3458         case  4: diffs |= __it_diff(a, b, 32);
3459                 break;
3460         }
3461         return diffs;
3462 #else
3463         return memcmp(a - meta_len, b - meta_len, meta_len);
3464 #endif
3465 }
3466 
3467 static inline bool skb_metadata_differs(const struct sk_buff *skb_a,
3468                                         const struct sk_buff *skb_b)
3469 {
3470         u8 len_a = skb_metadata_len(skb_a);
3471         u8 len_b = skb_metadata_len(skb_b);
3472 
3473         if (!(len_a | len_b))
3474                 return false;
3475 
3476         return len_a != len_b ?
3477                true : __skb_metadata_differs(skb_a, skb_b, len_a);
3478 }
3479 
3480 static inline void skb_metadata_set(struct sk_buff *skb, u8 meta_len)
3481 {
3482         skb_shinfo(skb)->meta_len = meta_len;
3483 }
3484 
3485 static inline void skb_metadata_clear(struct sk_buff *skb)
3486 {
3487         skb_metadata_set(skb, 0);
3488 }
3489 
3490 struct sk_buff *skb_clone_sk(struct sk_buff *skb);
3491 
3492 #ifdef CONFIG_NETWORK_PHY_TIMESTAMPING
3493 
3494 void skb_clone_tx_timestamp(struct sk_buff *skb);
3495 bool skb_defer_rx_timestamp(struct sk_buff *skb);
3496 
3497 #else /* CONFIG_NETWORK_PHY_TIMESTAMPING */
3498 
3499 static inline void skb_clone_tx_timestamp(struct sk_buff *skb)
3500 {
3501 }
3502 
3503 static inline bool skb_defer_rx_timestamp(struct sk_buff *skb)
3504 {
3505         return false;
3506 }
3507 
3508 #endif /* !CONFIG_NETWORK_PHY_TIMESTAMPING */
3509 
3510 /**
3511  * skb_complete_tx_timestamp() - deliver cloned skb with tx timestamps
3512  *
3513  * PHY drivers may accept clones of transmitted packets for
3514  * timestamping via their phy_driver.txtstamp method. These drivers
3515  * must call this function to return the skb back to the stack with a
3516  * timestamp.
3517  *
3518  * @skb: clone of the the original outgoing packet
3519  * @hwtstamps: hardware time stamps
3520  *
3521  */
3522 void skb_complete_tx_timestamp(struct sk_buff *skb,
3523                                struct skb_shared_hwtstamps *hwtstamps);
3524 
3525 void __skb_tstamp_tx(struct sk_buff *orig_skb,
3526                      struct skb_shared_hwtstamps *hwtstamps,
3527                      struct sock *sk, int tstype);
3528 
3529 /**
3530  * skb_tstamp_tx - queue clone of skb with send time stamps
3531  * @orig_skb:   the original outgoing packet
3532  * @hwtstamps:  hardware time stamps, may be NULL if not available
3533  *
3534  * If the skb has a socket associated, then this function clones the
3535  * skb (thus sharing the actual data and optional structures), stores
3536  * the optional hardware time stamping information (if non NULL) or
3537  * generates a software time stamp (otherwise), then queues the clone
3538  * to the error queue of the socket.  Errors are silently ignored.
3539  */
3540 void skb_tstamp_tx(struct sk_buff *orig_skb,
3541                    struct skb_shared_hwtstamps *hwtstamps);
3542 
3543 /**
3544  * skb_tx_timestamp() - Driver hook for transmit timestamping
3545  *
3546  * Ethernet MAC Drivers should call this function in their hard_xmit()
3547  * function immediately before giving the sk_buff to the MAC hardware.
3548  *
3549  * Specifically, one should make absolutely sure that this function is
3550  * called before TX completion of this packet can trigger.  Otherwise
3551  * the packet could potentially already be freed.
3552  *
3553  * @skb: A socket buffer.
3554  */
3555 static inline void skb_tx_timestamp(struct sk_buff *skb)
3556 {
3557         skb_clone_tx_timestamp(skb);
3558         if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP)
3559                 skb_tstamp_tx(skb, NULL);
3560 }
3561 
3562 /**
3563  * skb_complete_wifi_ack - deliver skb with wifi status
3564  *
3565  * @skb: the original outgoing packet
3566  * @acked: ack status
3567  *
3568  */
3569 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked);
3570 
3571 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
3572 __sum16 __skb_checksum_complete(struct sk_buff *skb);
3573 
3574 static inline int skb_csum_unnecessary(const struct sk_buff *skb)
3575 {
3576         return ((skb->ip_summed == CHECKSUM_UNNECESSARY) ||
3577                 skb->csum_valid ||
3578                 (skb->ip_summed == CHECKSUM_PARTIAL &&
3579                  skb_checksum_start_offset(skb) >= 0));
3580 }
3581 
3582 /**
3583  *      skb_checksum_complete - Calculate checksum of an entire packet
3584  *      @skb: packet to process
3585  *
3586  *      This function calculates the checksum over the entire packet plus
3587  *      the value of skb->csum.  The latter can be used to supply the
3588  *      checksum of a pseudo header as used by TCP/UDP.  It returns the
3589  *      checksum.
3590  *
3591  *      For protocols that contain complete checksums such as ICMP/TCP/UDP,
3592  *      this function can be used to verify that checksum on received
3593  *      packets.  In that case the function should return zero if the
3594  *      checksum is correct.  In particular, this function will return zero
3595  *      if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
3596  *      hardware has already verified the correctness of the checksum.
3597  */
3598 static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
3599 {
3600         return skb_csum_unnecessary(skb) ?
3601                0 : __skb_checksum_complete(skb);
3602 }
3603 
3604 static inline void __skb_decr_checksum_unnecessary(struct sk_buff *skb)
3605 {
3606         if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
3607                 if (skb->csum_level == 0)
3608                         skb->ip_summed = CHECKSUM_NONE;
3609                 else
3610                         skb->csum_level--;
3611         }
3612 }
3613 
3614 static inline void __skb_incr_checksum_unnecessary(struct sk_buff *skb)
3615 {
3616         if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
3617                 if (skb->csum_level < SKB_MAX_CSUM_LEVEL)
3618                         skb->csum_level++;
3619         } else if (skb->ip_summed == CHECKSUM_NONE) {
3620                 skb->ip_summed = CHECKSUM_UNNECESSARY;
3621                 skb->csum_level = 0;
3622         }
3623 }
3624 
3625 /* Check if we need to perform checksum complete validation.
3626  *
3627  * Returns true if checksum complete is needed, false otherwise
3628  * (either checksum is unnecessary or zero checksum is allowed).
3629  */
3630 static inline bool __skb_checksum_validate_needed(struct sk_buff *skb,
3631                                                   bool zero_okay,
3632                                                   __sum16 check)
3633 {
3634         if (skb_csum_unnecessary(skb) || (zero_okay && !check)) {
3635                 skb->csum_valid = 1;
3636                 __skb_decr_checksum_unnecessary(skb);
3637                 return false;
3638         }
3639 
3640         return true;
3641 }
3642 
3643 /* For small packets <= CHECKSUM_BREAK peform checksum complete directly
3644  * in checksum_init.
3645  */
3646 #define CHECKSUM_BREAK 76
3647 
3648 /* Unset checksum-complete
3649  *
3650  * Unset checksum complete can be done when packet is being modified
3651  * (uncompressed for instance) and checksum-complete value is
3652  * invalidated.
3653  */
3654 static inline void skb_checksum_complete_unset(struct sk_buff *skb)
3655 {
3656         if (skb->ip_summed == CHECKSUM_COMPLETE)
3657                 skb->ip_summed = CHECKSUM_NONE;
3658 }
3659 
3660 /* Validate (init) checksum based on checksum complete.
3661  *
3662  * Return values:
3663  *   0: checksum is validated or try to in skb_checksum_complete. In the latter
3664  *      case the ip_summed will not be CHECKSUM_UNNECESSARY and the pseudo
3665  *      checksum is stored in skb->csum for use in __skb_checksum_complete
3666  *   non-zero: value of invalid checksum
3667  *
3668  */
3669 static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb,
3670                                                        bool complete,
3671                                                        __wsum psum)
3672 {
3673         if (skb->ip_summed == CHECKSUM_COMPLETE) {
3674                 if (!csum_fold(csum_add(psum, skb->csum))) {
3675                         skb->csum_valid = 1;
3676                         return 0;
3677                 }
3678         }
3679 
3680         skb->csum = psum;
3681 
3682         if (complete || skb->len <= CHECKSUM_BREAK) {
3683                 __sum16 csum;
3684 
3685                 csum = __skb_checksum_complete(skb);
3686                 skb->csum_valid = !csum;
3687                 return csum;
3688         }
3689 
3690         return 0;
3691 }
3692 
3693 static inline __wsum null_compute_pseudo(struct sk_buff *skb, int proto)
3694 {
3695         return 0;
3696 }
3697 
3698 /* Perform checksum validate (init). Note that this is a macro since we only
3699  * want to calculate the pseudo header which is an input function if necessary.
3700  * First we try to validate without any computation (checksum unnecessary) and
3701  * then calculate based on checksum complete calling the function to compute
3702  * pseudo header.
3703  *
3704  * Return values:
3705  *   0: checksum is validated or try to in skb_checksum_complete
3706  *   non-zero: value of invalid checksum
3707  */
3708 #define __skb_checksum_validate(skb, proto, complete,                   \
3709                                 zero_okay, check, compute_pseudo)       \
3710 ({                                                                      \
3711         __sum16 __ret = 0;                                              \
3712         skb->csum_valid = 0;                                            \
3713         if (__skb_checksum_validate_needed(skb, zero_okay, check))      \
3714                 __ret = __skb_checksum_validate_complete(skb,           \
3715                                 complete, compute_pseudo(skb, proto));  \
3716         __ret;                                                          \
3717 })
3718 
3719 #define skb_checksum_init(skb, proto, compute_pseudo)                   \
3720         __skb_checksum_validate(skb, proto, false, false, 0, compute_pseudo)
3721 
3722 #define skb_checksum_init_zero_check(skb, proto, check, compute_pseudo) \
3723         __skb_checksum_validate(skb, proto, false, true, check, compute_pseudo)
3724 
3725 #define skb_checksum_validate(skb, proto, compute_pseudo)               \
3726         __skb_checksum_validate(skb, proto, true, false, 0, compute_pseudo)
3727 
3728 #define skb_checksum_validate_zero_check(skb, proto, check,             \
3729                                          compute_pseudo)                \
3730         __skb_checksum_validate(skb, proto, true, true, check, compute_pseudo)
3731 
3732 #define skb_checksum_simple_validate(skb)                               \
3733         __skb_checksum_validate(skb, 0, true, false, 0, null_compute_pseudo)
3734 
3735 static inline bool __skb_checksum_convert_check(struct sk_buff *skb)
3736 {
3737         return (skb->ip_summed == CHECKSUM_NONE && skb->csum_valid);
3738 }
3739 
3740 static inline void __skb_checksum_convert(struct sk_buff *skb,
3741                                           __sum16 check, __wsum pseudo)
3742 {
3743         skb->csum = ~pseudo;
3744         skb->ip_summed = CHECKSUM_COMPLETE;
3745 }
3746 
3747 #define skb_checksum_try_convert(skb, proto, check, compute_pseudo)     \
3748 do {                                                                    \
3749         if (__skb_checksum_convert_check(skb))                          \
3750                 __skb_checksum_convert(skb, check,                      \
3751                                        compute_pseudo(skb, proto));     \
3752 } while (0)
3753 
3754 static inline void skb_remcsum_adjust_partial(struct sk_buff *skb, void *ptr,
3755                                               u16 start, u16 offset)
3756 {
3757         skb->ip_summed = CHECKSUM_PARTIAL;
3758         skb->csum_start = ((unsigned char *)ptr + start) - skb->head;
3759         skb->csum_offset = offset - start;
3760 }
3761 
3762 /* Update skbuf and packet to reflect the remote checksum offload operation.
3763  * When called, ptr indicates the starting point for skb->csum when
3764  * ip_summed is CHECKSUM_COMPLETE. If we need create checksum complete
3765  * here, skb_postpull_rcsum is done so skb->csum start is ptr.
3766  */
3767 static inline void skb_remcsum_process(struct sk_buff *skb, void *ptr,
3768                                        int start, int offset, bool nopartial)
3769 {
3770         __wsum delta;
3771 
3772         if (!nopartial) {
3773                 skb_remcsum_adjust_partial(skb, ptr, start, offset);
3774                 return;
3775         }
3776 
3777          if (unlikely(skb->ip_summed != CHECKSUM_COMPLETE)) {
3778                 __skb_checksum_complete(skb);
3779                 skb_postpull_rcsum(skb, skb->data, ptr - (void *)skb->data);
3780         }
3781 
3782         delta = remcsum_adjust(ptr, skb->csum, start, offset);
3783 
3784         /* Adjust skb->csum since we changed the packet */
3785         skb->csum = csum_add(skb->csum, delta);
3786 }
3787 
3788 static inline struct nf_conntrack *skb_nfct(const struct sk_buff *skb)
3789 {
3790 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
3791         return (void *)(skb->_nfct & SKB_NFCT_PTRMASK);
3792 #else
3793         return NULL;
3794 #endif
3795 }
3796 
3797 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3798 void nf_conntrack_destroy(struct nf_conntrack *nfct);
3799 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
3800 {
3801         if (nfct && atomic_dec_and_test(&nfct->use))
3802                 nf_conntrack_destroy(nfct);
3803 }
3804 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
3805 {
3806         if (nfct)
3807                 atomic_inc(&nfct->use);
3808 }
3809 #endif
3810 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3811 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
3812 {
3813         if (nf_bridge && refcount_dec_and_test(&nf_bridge->use))
3814                 kfree(nf_bridge);
3815 }
3816 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
3817 {
3818         if (nf_bridge)
3819                 refcount_inc(&nf_bridge->use);
3820 }
3821 #endif /* CONFIG_BRIDGE_NETFILTER */
3822 static inline void nf_reset(struct sk_buff *skb)
3823 {
3824 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3825         nf_conntrack_put(skb_nfct(skb));
3826         skb->_nfct = 0;
3827 #endif
3828 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3829         nf_bridge_put(skb->nf_bridge);
3830         skb->nf_bridge = NULL;
3831 #endif
3832 }
3833 
3834 static inline void nf_reset_trace(struct sk_buff *skb)
3835 {
3836 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
3837         skb->nf_trace = 0;
3838 #endif
3839 }
3840 
3841 static inline void ipvs_reset(struct sk_buff *skb)
3842 {
3843 #if IS_ENABLED(CONFIG_IP_VS)
3844         skb->ipvs_property = 0;
3845 #endif
3846 }
3847 
3848 /* Note: This doesn't put any conntrack and bridge info in dst. */
3849 static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src,
3850                              bool copy)
3851 {
3852 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3853         dst->_nfct = src->_nfct;
3854         nf_conntrack_get(skb_nfct(src));
3855 #endif
3856 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3857         dst->nf_bridge  = src->nf_bridge;
3858         nf_bridge_get(src->nf_bridge);
3859 #endif
3860 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
3861         if (copy)
3862                 dst->nf_trace = src->nf_trace;
3863 #endif
3864 }
3865 
3866 static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
3867 {
3868 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3869         nf_conntrack_put(skb_nfct(dst));
3870 #endif
3871 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3872         nf_bridge_put(dst->nf_bridge);
3873 #endif
3874         __nf_copy(dst, src, true);
3875 }
3876 
3877 #ifdef CONFIG_NETWORK_SECMARK
3878 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
3879 {
3880         to->secmark = from->secmark;
3881 }
3882 
3883 static inline void skb_init_secmark(struct sk_buff *skb)
3884 {
3885         skb->secmark = 0;
3886 }
3887 #else
3888 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
3889 { }
3890 
3891 static inline void skb_init_secmark(struct sk_buff *skb)
3892 { }
3893 #endif
3894 
3895 static inline bool skb_irq_freeable(const struct sk_buff *skb)
3896 {
3897         return !skb->destructor &&
3898 #if IS_ENABLED(CONFIG_XFRM)
3899                 !skb->sp &&
3900 #endif
3901                 !skb_nfct(skb) &&
3902                 !skb->_skb_refdst &&
3903                 !skb_has_frag_list(skb);
3904 }
3905 
3906 static inline void skb_set_queue_mapping(struct sk_buff *skb, u16 queue_mapping)
3907 {
3908         skb->queue_mapping = queue_mapping;
3909 }
3910 
3911 static inline u16 skb_get_queue_mapping(const struct sk_buff *skb)
3912 {
3913         return skb->queue_mapping;
3914 }
3915 
3916 static inline void skb_copy_queue_mapping(struct sk_buff *to, const struct sk_buff *from)
3917 {
3918         to->queue_mapping = from->queue_mapping;
3919 }
3920 
3921 static inline void skb_record_rx_queue(struct sk_buff *skb, u16 rx_queue)
3922 {
3923         skb->queue_mapping = rx_queue + 1;
3924 }
3925 
3926 static inline u16 skb_get_rx_queue(const struct sk_buff *skb)
3927 {
3928         return skb->queue_mapping - 1;
3929 }
3930 
3931 static inline bool skb_rx_queue_recorded(const struct sk_buff *skb)
3932 {
3933         return skb->queue_mapping != 0;
3934 }
3935 
3936 static inline void skb_set_dst_pending_confirm(struct sk_buff *skb, u32 val)
3937 {
3938         skb->dst_pending_confirm = val;
3939 }
3940 
3941 static inline bool skb_get_dst_pending_confirm(const struct sk_buff *skb)
3942 {
3943         return skb->dst_pending_confirm != 0;
3944 }
3945 
3946 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
3947 {
3948 #ifdef CONFIG_XFRM
3949         return skb->sp;
3950 #else
3951         return NULL;
3952 #endif
3953 }
3954 
3955 /* Keeps track of mac header offset relative to skb->head.
3956  * It is useful for TSO of Tunneling protocol. e.g. GRE.
3957  * For non-tunnel skb it points to skb_mac_header() and for
3958  * tunnel skb it points to outer mac header.
3959  * Keeps track of level of encapsulation of network headers.
3960  */
3961 struct skb_gso_cb {
3962         union {
3963                 int     mac_offset;
3964                 int     data_offset;
3965         };
3966         int     encap_level;
3967         __wsum  csum;
3968         __u16   csum_start;
3969 };
3970 #define SKB_SGO_CB_OFFSET       32
3971 #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)((skb)->cb + SKB_SGO_CB_OFFSET))
3972 
3973 static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
3974 {
3975         return (skb_mac_header(inner_skb) - inner_skb->head) -
3976                 SKB_GSO_CB(inner_skb)->mac_offset;
3977 }
3978 
3979 static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
3980 {
3981         int new_headroom, headroom;
3982         int ret;
3983 
3984         headroom = skb_headroom(skb);
3985         ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);
3986         if (ret)
3987                 return ret;
3988 
3989         new_headroom = skb_headroom(skb);
3990         SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);
3991         return 0;
3992 }
3993 
3994 static inline void gso_reset_checksum(struct sk_buff *skb, __wsum res)
3995 {
3996         /* Do not update partial checksums if remote checksum is enabled. */
3997         if (skb->remcsum_offload)
3998                 return;
3999 
4000         SKB_GSO_CB(skb)->csum = res;
4001         SKB_GSO_CB(skb)->csum_start = skb_checksum_start(skb) - skb->head;
4002 }
4003 
4004 /* Compute the checksum for a gso segment. First compute the checksum value
4005  * from the start of transport header to SKB_GSO_CB(skb)->csum_start, and
4006  * then add in skb->csum (checksum from csum_start to end of packet).
4007  * skb->csum and csum_start are then updated to reflect the checksum of the
4008  * resultant packet starting from the transport header-- the resultant checksum
4009  * is in the res argument (i.e. normally zero or ~ of checksum of a pseudo
4010  * header.
4011  */
4012 static inline __sum16 gso_make_checksum(struct sk_buff *skb, __wsum res)
4013 {
4014         unsigned char *csum_start = skb_transport_header(skb);
4015         int plen = (skb->head + SKB_GSO_CB(skb)->csum_start) - csum_start;
4016         __wsum partial = SKB_GSO_CB(skb)->csum;
4017 
4018         SKB_GSO_CB(skb)->csum = res;
4019         SKB_GSO_CB(skb)->csum_start = csum_start - skb->head;
4020 
4021         return csum_fold(csum_partial(csum_start, plen, partial));
4022 }
4023 
4024 static inline bool skb_is_gso(const struct sk_buff *skb)
4025 {
4026         return skb_shinfo(skb)->gso_size;
4027 }
4028 
4029 /* Note: Should be called only if skb_is_gso(skb) is true */
4030 static inline bool skb_is_gso_v6(const struct sk_buff *skb)
4031 {
4032         return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
4033 }
4034 
4035 static inline void skb_gso_reset(struct sk_buff *skb)
4036 {
4037         skb_shinfo(skb)->gso_size = 0;
4038         skb_shinfo(skb)->gso_segs = 0;
4039         skb_shinfo(skb)->gso_type = 0;
4040 }
4041 
4042 void __skb_warn_lro_forwarding(const struct sk_buff *skb);
4043 
4044 static inline bool skb_warn_if_lro(const struct sk_buff *skb)
4045 {
4046         /* LRO sets gso_size but not gso_type, whereas if GSO is really
4047          * wanted then gso_type will be set. */
4048         const struct skb_shared_info *shinfo = skb_shinfo(skb);
4049 
4050         if (skb_is_nonlinear(skb) && shinfo->gso_size != 0 &&
4051             unlikely(shinfo->gso_type == 0)) {
4052                 __skb_warn_lro_forwarding(skb);
4053                 return true;
4054         }
4055         return false;
4056 }
4057 
4058 static inline void skb_forward_csum(struct sk_buff *skb)
4059 {
4060         /* Unfortunately we don't support this one.  Any brave souls? */
4061         if (skb->ip_summed == CHECKSUM_COMPLETE)
4062                 skb->ip_summed = CHECKSUM_NONE;
4063 }
4064 
4065 /**
4066  * skb_checksum_none_assert - make sure skb ip_summed is CHECKSUM_NONE
4067  * @skb: skb to check
4068  *
4069  * fresh skbs have their ip_summed set to CHECKSUM_NONE.
4070  * Instead of forcing ip_summed to CHECKSUM_NONE, we can
4071  * use this helper, to document places where we make this assertion.
4072  */
4073 static inline void skb_checksum_none_assert(const struct sk_buff *skb)
4074 {
4075 #ifdef DEBUG
4076         BUG_ON(skb->ip_summed != CHECKSUM_NONE);
4077 #endif
4078 }
4079 
4080 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
4081 
4082 int skb_checksum_setup(struct sk_buff *skb, bool recalculate);
4083 struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
4084                                      unsigned int transport_len,
4085                                      __sum16(*skb_chkf)(struct sk_buff *skb));
4086 
4087 /**
4088  * skb_head_is_locked - Determine if the skb->head is locked down
4089  * @skb: skb to check
4090  *
4091  * The head on skbs build around a head frag can be removed if they are
4092  * not cloned.  This function returns true if the skb head is locked down
4093  * due to either being allocated via kmalloc, or by being a clone with
4094  * multiple references to the head.
4095  */
4096 static inline bool skb_head_is_locked(const struct sk_buff *skb)
4097 {
4098         return !skb->head_frag || skb_cloned(skb);
4099 }
4100 
4101 /**
4102  * skb_gso_network_seglen - Return length of individual segments of a gso packet
4103  *
4104  * @skb: GSO skb
4105  *
4106  * skb_gso_network_seglen is used to determine the real size of the
4107  * individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP).
4108  *
4109  * The MAC/L2 header is not accounted for.
4110  */
4111 static inline unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
4112 {
4113         unsigned int hdr_len = skb_transport_header(skb) -
4114                                skb_network_header(skb);
4115         return hdr_len + skb_gso_transport_seglen(skb);
4116 }
4117 
4118 /* Local Checksum Offload.
4119  * Compute outer checksum based on the assumption that the
4120  * inner checksum will be offloaded later.
4121  * See Documentation/networking/checksum-offloads.txt for
4122  * explanation of how this works.
4123  * Fill in outer checksum adjustment (e.g. with sum of outer
4124  * pseudo-header) before calling.
4125  * Also ensure that inner checksum is in linear data area.
4126  */
4127 static inline __wsum lco_csum(struct sk_buff *skb)
4128 {
4129         unsigned char *csum_start = skb_checksum_start(skb);
4130         unsigned char *l4_hdr = skb_transport_header(skb);
4131         __wsum partial;
4132 
4133         /* Start with complement of inner checksum adjustment */
4134         partial = ~csum_unfold(*(__force __sum16 *)(csum_start +
4135                                                     skb->csum_offset));
4136 
4137         /* Add in checksum of our headers (incl. outer checksum
4138          * adjustment filled in by caller) and return result.
4139          */
4140         return csum_partial(l4_hdr, csum_start - l4_hdr, partial);
4141 }
4142 
4143 #endif  /* __KERNEL__ */
4144 #endif  /* _LINUX_SKBUFF_H */
4145 

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