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TOMOYO Linux Cross Reference
Linux/include/net/dst.h

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  1 /* SPDX-License-Identifier: GPL-2.0 */
  2 /*
  3  * net/dst.h    Protocol independent destination cache definitions.
  4  *
  5  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  6  *
  7  */
  8 
  9 #ifndef _NET_DST_H
 10 #define _NET_DST_H
 11 
 12 #include <net/dst_ops.h>
 13 #include <linux/netdevice.h>
 14 #include <linux/rtnetlink.h>
 15 #include <linux/rcupdate.h>
 16 #include <linux/bug.h>
 17 #include <linux/jiffies.h>
 18 #include <linux/refcount.h>
 19 #include <net/neighbour.h>
 20 #include <asm/processor.h>
 21 
 22 struct sk_buff;
 23 
 24 struct dst_entry {
 25         struct net_device       *dev;
 26         struct  dst_ops         *ops;
 27         unsigned long           _metrics;
 28         unsigned long           expires;
 29 #ifdef CONFIG_XFRM
 30         struct xfrm_state       *xfrm;
 31 #else
 32         void                    *__pad1;
 33 #endif
 34         int                     (*input)(struct sk_buff *);
 35         int                     (*output)(struct net *net, struct sock *sk, struct sk_buff *skb);
 36 
 37         unsigned short          flags;
 38 #define DST_HOST                0x0001
 39 #define DST_NOXFRM              0x0002
 40 #define DST_NOPOLICY            0x0004
 41 #define DST_NOCOUNT             0x0008
 42 #define DST_FAKE_RTABLE         0x0010
 43 #define DST_XFRM_TUNNEL         0x0020
 44 #define DST_XFRM_QUEUE          0x0040
 45 #define DST_METADATA            0x0080
 46 
 47         /* A non-zero value of dst->obsolete forces by-hand validation
 48          * of the route entry.  Positive values are set by the generic
 49          * dst layer to indicate that the entry has been forcefully
 50          * destroyed.
 51          *
 52          * Negative values are used by the implementation layer code to
 53          * force invocation of the dst_ops->check() method.
 54          */
 55         short                   obsolete;
 56 #define DST_OBSOLETE_NONE       0
 57 #define DST_OBSOLETE_DEAD       2
 58 #define DST_OBSOLETE_FORCE_CHK  -1
 59 #define DST_OBSOLETE_KILL       -2
 60         unsigned short          header_len;     /* more space at head required */
 61         unsigned short          trailer_len;    /* space to reserve at tail */
 62 
 63         /*
 64          * __refcnt wants to be on a different cache line from
 65          * input/output/ops or performance tanks badly
 66          */
 67 #ifdef CONFIG_64BIT
 68         atomic_t                __refcnt;       /* 64-bit offset 64 */
 69 #endif
 70         int                     __use;
 71         unsigned long           lastuse;
 72         struct lwtunnel_state   *lwtstate;
 73         struct rcu_head         rcu_head;
 74         short                   error;
 75         short                   __pad;
 76         __u32                   tclassid;
 77 #ifndef CONFIG_64BIT
 78         atomic_t                __refcnt;       /* 32-bit offset 64 */
 79 #endif
 80 };
 81 
 82 struct dst_metrics {
 83         u32             metrics[RTAX_MAX];
 84         refcount_t      refcnt;
 85 };
 86 extern const struct dst_metrics dst_default_metrics;
 87 
 88 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
 89 
 90 #define DST_METRICS_READ_ONLY           0x1UL
 91 #define DST_METRICS_REFCOUNTED          0x2UL
 92 #define DST_METRICS_FLAGS               0x3UL
 93 #define __DST_METRICS_PTR(Y)    \
 94         ((u32 *)((Y) & ~DST_METRICS_FLAGS))
 95 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
 96 
 97 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
 98 {
 99         return dst->_metrics & DST_METRICS_READ_ONLY;
100 }
101 
102 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
103 
104 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
105 {
106         unsigned long val = dst->_metrics;
107         if (!(val & DST_METRICS_READ_ONLY))
108                 __dst_destroy_metrics_generic(dst, val);
109 }
110 
111 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
112 {
113         unsigned long p = dst->_metrics;
114 
115         BUG_ON(!p);
116 
117         if (p & DST_METRICS_READ_ONLY)
118                 return dst->ops->cow_metrics(dst, p);
119         return __DST_METRICS_PTR(p);
120 }
121 
122 /* This may only be invoked before the entry has reached global
123  * visibility.
124  */
125 static inline void dst_init_metrics(struct dst_entry *dst,
126                                     const u32 *src_metrics,
127                                     bool read_only)
128 {
129         dst->_metrics = ((unsigned long) src_metrics) |
130                 (read_only ? DST_METRICS_READ_ONLY : 0);
131 }
132 
133 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
134 {
135         u32 *dst_metrics = dst_metrics_write_ptr(dest);
136 
137         if (dst_metrics) {
138                 u32 *src_metrics = DST_METRICS_PTR(src);
139 
140                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
141         }
142 }
143 
144 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
145 {
146         return DST_METRICS_PTR(dst);
147 }
148 
149 static inline u32
150 dst_metric_raw(const struct dst_entry *dst, const int metric)
151 {
152         u32 *p = DST_METRICS_PTR(dst);
153 
154         return p[metric-1];
155 }
156 
157 static inline u32
158 dst_metric(const struct dst_entry *dst, const int metric)
159 {
160         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
161                      metric == RTAX_ADVMSS ||
162                      metric == RTAX_MTU);
163         return dst_metric_raw(dst, metric);
164 }
165 
166 static inline u32
167 dst_metric_advmss(const struct dst_entry *dst)
168 {
169         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
170 
171         if (!advmss)
172                 advmss = dst->ops->default_advmss(dst);
173 
174         return advmss;
175 }
176 
177 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
178 {
179         u32 *p = dst_metrics_write_ptr(dst);
180 
181         if (p)
182                 p[metric-1] = val;
183 }
184 
185 /* Kernel-internal feature bits that are unallocated in user space. */
186 #define DST_FEATURE_ECN_CA      (1U << 31)
187 
188 #define DST_FEATURE_MASK        (DST_FEATURE_ECN_CA)
189 #define DST_FEATURE_ECN_MASK    (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN)
190 
191 static inline u32
192 dst_feature(const struct dst_entry *dst, u32 feature)
193 {
194         return dst_metric(dst, RTAX_FEATURES) & feature;
195 }
196 
197 static inline u32 dst_mtu(const struct dst_entry *dst)
198 {
199         return dst->ops->mtu(dst);
200 }
201 
202 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
203 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
204 {
205         return msecs_to_jiffies(dst_metric(dst, metric));
206 }
207 
208 static inline u32
209 dst_allfrag(const struct dst_entry *dst)
210 {
211         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
212         return ret;
213 }
214 
215 static inline int
216 dst_metric_locked(const struct dst_entry *dst, int metric)
217 {
218         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
219 }
220 
221 static inline void dst_hold(struct dst_entry *dst)
222 {
223         /*
224          * If your kernel compilation stops here, please check
225          * the placement of __refcnt in struct dst_entry
226          */
227         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
228         WARN_ON(atomic_inc_not_zero(&dst->__refcnt) == 0);
229 }
230 
231 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
232 {
233         if (unlikely(time != dst->lastuse)) {
234                 dst->__use++;
235                 dst->lastuse = time;
236         }
237 }
238 
239 static inline void dst_hold_and_use(struct dst_entry *dst, unsigned long time)
240 {
241         dst_hold(dst);
242         dst_use_noref(dst, time);
243 }
244 
245 static inline struct dst_entry *dst_clone(struct dst_entry *dst)
246 {
247         if (dst)
248                 dst_hold(dst);
249         return dst;
250 }
251 
252 void dst_release(struct dst_entry *dst);
253 
254 void dst_release_immediate(struct dst_entry *dst);
255 
256 static inline void refdst_drop(unsigned long refdst)
257 {
258         if (!(refdst & SKB_DST_NOREF))
259                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
260 }
261 
262 /**
263  * skb_dst_drop - drops skb dst
264  * @skb: buffer
265  *
266  * Drops dst reference count if a reference was taken.
267  */
268 static inline void skb_dst_drop(struct sk_buff *skb)
269 {
270         if (skb->_skb_refdst) {
271                 refdst_drop(skb->_skb_refdst);
272                 skb->_skb_refdst = 0UL;
273         }
274 }
275 
276 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst)
277 {
278         nskb->_skb_refdst = refdst;
279         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
280                 dst_clone(skb_dst(nskb));
281 }
282 
283 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
284 {
285         __skb_dst_copy(nskb, oskb->_skb_refdst);
286 }
287 
288 /**
289  * dst_hold_safe - Take a reference on a dst if possible
290  * @dst: pointer to dst entry
291  *
292  * This helper returns false if it could not safely
293  * take a reference on a dst.
294  */
295 static inline bool dst_hold_safe(struct dst_entry *dst)
296 {
297         return atomic_inc_not_zero(&dst->__refcnt);
298 }
299 
300 /**
301  * skb_dst_force - makes sure skb dst is refcounted
302  * @skb: buffer
303  *
304  * If dst is not yet refcounted and not destroyed, grab a ref on it.
305  * Returns true if dst is refcounted.
306  */
307 static inline bool skb_dst_force(struct sk_buff *skb)
308 {
309         if (skb_dst_is_noref(skb)) {
310                 struct dst_entry *dst = skb_dst(skb);
311 
312                 WARN_ON(!rcu_read_lock_held());
313                 if (!dst_hold_safe(dst))
314                         dst = NULL;
315 
316                 skb->_skb_refdst = (unsigned long)dst;
317         }
318 
319         return skb->_skb_refdst != 0UL;
320 }
321 
322 
323 /**
324  *      __skb_tunnel_rx - prepare skb for rx reinsert
325  *      @skb: buffer
326  *      @dev: tunnel device
327  *      @net: netns for packet i/o
328  *
329  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
330  *      so make some cleanups. (no accounting done)
331  */
332 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
333                                    struct net *net)
334 {
335         skb->dev = dev;
336 
337         /*
338          * Clear hash so that we can recalulate the hash for the
339          * encapsulated packet, unless we have already determine the hash
340          * over the L4 4-tuple.
341          */
342         skb_clear_hash_if_not_l4(skb);
343         skb_set_queue_mapping(skb, 0);
344         skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
345 }
346 
347 /**
348  *      skb_tunnel_rx - prepare skb for rx reinsert
349  *      @skb: buffer
350  *      @dev: tunnel device
351  *      @net: netns for packet i/o
352  *
353  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
354  *      so make some cleanups, and perform accounting.
355  *      Note: this accounting is not SMP safe.
356  */
357 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
358                                  struct net *net)
359 {
360         /* TODO : stats should be SMP safe */
361         dev->stats.rx_packets++;
362         dev->stats.rx_bytes += skb->len;
363         __skb_tunnel_rx(skb, dev, net);
364 }
365 
366 static inline u32 dst_tclassid(const struct sk_buff *skb)
367 {
368 #ifdef CONFIG_IP_ROUTE_CLASSID
369         const struct dst_entry *dst;
370 
371         dst = skb_dst(skb);
372         if (dst)
373                 return dst->tclassid;
374 #endif
375         return 0;
376 }
377 
378 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
379 static inline int dst_discard(struct sk_buff *skb)
380 {
381         return dst_discard_out(&init_net, skb->sk, skb);
382 }
383 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref,
384                 int initial_obsolete, unsigned short flags);
385 void dst_init(struct dst_entry *dst, struct dst_ops *ops,
386               struct net_device *dev, int initial_ref, int initial_obsolete,
387               unsigned short flags);
388 struct dst_entry *dst_destroy(struct dst_entry *dst);
389 void dst_dev_put(struct dst_entry *dst);
390 
391 static inline void dst_confirm(struct dst_entry *dst)
392 {
393 }
394 
395 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
396 {
397         struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
398         return IS_ERR(n) ? NULL : n;
399 }
400 
401 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
402                                                      struct sk_buff *skb)
403 {
404         struct neighbour *n =  dst->ops->neigh_lookup(dst, skb, NULL);
405         return IS_ERR(n) ? NULL : n;
406 }
407 
408 static inline void dst_confirm_neigh(const struct dst_entry *dst,
409                                      const void *daddr)
410 {
411         if (dst->ops->confirm_neigh)
412                 dst->ops->confirm_neigh(dst, daddr);
413 }
414 
415 static inline void dst_link_failure(struct sk_buff *skb)
416 {
417         struct dst_entry *dst = skb_dst(skb);
418         if (dst && dst->ops && dst->ops->link_failure)
419                 dst->ops->link_failure(skb);
420 }
421 
422 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
423 {
424         unsigned long expires = jiffies + timeout;
425 
426         if (expires == 0)
427                 expires = 1;
428 
429         if (dst->expires == 0 || time_before(expires, dst->expires))
430                 dst->expires = expires;
431 }
432 
433 /* Output packet to network from transport.  */
434 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb)
435 {
436         return skb_dst(skb)->output(net, sk, skb);
437 }
438 
439 /* Input packet from network to transport.  */
440 static inline int dst_input(struct sk_buff *skb)
441 {
442         return skb_dst(skb)->input(skb);
443 }
444 
445 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
446 {
447         if (dst->obsolete)
448                 dst = dst->ops->check(dst, cookie);
449         return dst;
450 }
451 
452 /* Flags for xfrm_lookup flags argument. */
453 enum {
454         XFRM_LOOKUP_ICMP = 1 << 0,
455         XFRM_LOOKUP_QUEUE = 1 << 1,
456         XFRM_LOOKUP_KEEP_DST_REF = 1 << 2,
457 };
458 
459 struct flowi;
460 #ifndef CONFIG_XFRM
461 static inline struct dst_entry *xfrm_lookup(struct net *net,
462                                             struct dst_entry *dst_orig,
463                                             const struct flowi *fl,
464                                             const struct sock *sk,
465                                             int flags)
466 {
467         return dst_orig;
468 }
469 
470 static inline struct dst_entry *
471 xfrm_lookup_with_ifid(struct net *net, struct dst_entry *dst_orig,
472                       const struct flowi *fl, const struct sock *sk,
473                       int flags, u32 if_id)
474 {
475         return dst_orig;
476 }
477 
478 static inline struct dst_entry *xfrm_lookup_route(struct net *net,
479                                                   struct dst_entry *dst_orig,
480                                                   const struct flowi *fl,
481                                                   const struct sock *sk,
482                                                   int flags)
483 {
484         return dst_orig;
485 }
486 
487 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
488 {
489         return NULL;
490 }
491 
492 #else
493 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
494                               const struct flowi *fl, const struct sock *sk,
495                               int flags);
496 
497 struct dst_entry *xfrm_lookup_with_ifid(struct net *net,
498                                         struct dst_entry *dst_orig,
499                                         const struct flowi *fl,
500                                         const struct sock *sk, int flags,
501                                         u32 if_id);
502 
503 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
504                                     const struct flowi *fl, const struct sock *sk,
505                                     int flags);
506 
507 /* skb attached with this dst needs transformation if dst->xfrm is valid */
508 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
509 {
510         return dst->xfrm;
511 }
512 #endif
513 
514 static inline void skb_dst_update_pmtu(struct sk_buff *skb, u32 mtu)
515 {
516         struct dst_entry *dst = skb_dst(skb);
517 
518         if (dst && dst->ops->update_pmtu)
519                 dst->ops->update_pmtu(dst, NULL, skb, mtu);
520 }
521 
522 static inline void skb_tunnel_check_pmtu(struct sk_buff *skb,
523                                          struct dst_entry *encap_dst,
524                                          int headroom)
525 {
526         u32 encap_mtu = dst_mtu(encap_dst);
527 
528         if (skb->len > encap_mtu - headroom)
529                 skb_dst_update_pmtu(skb, encap_mtu - headroom);
530 }
531 
532 #endif /* _NET_DST_H */
533 

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