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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 #define DST_GC_MIN      (HZ/10)
 23 #define DST_GC_INC      (HZ/2)
 24 #define DST_GC_MAX      (120*HZ)
 25 
 26 /* Each dst_entry has reference count and sits in some parent list(s).
 27  * When it is removed from parent list, it is "freed" (dst_free).
 28  * After this it enters dead state (dst->obsolete > 0) and if its refcnt
 29  * is zero, it can be destroyed immediately, otherwise it is added
 30  * to gc list and garbage collector periodically checks the refcnt.
 31  */
 32 
 33 struct sk_buff;
 34 
 35 struct dst_entry {
 36         struct net_device       *dev;
 37         struct rcu_head         rcu_head;
 38         struct dst_entry        *child;
 39         struct  dst_ops         *ops;
 40         unsigned long           _metrics;
 41         unsigned long           expires;
 42         struct dst_entry        *path;
 43         struct dst_entry        *from;
 44 #ifdef CONFIG_XFRM
 45         struct xfrm_state       *xfrm;
 46 #else
 47         void                    *__pad1;
 48 #endif
 49         int                     (*input)(struct sk_buff *);
 50         int                     (*output)(struct net *net, struct sock *sk, struct sk_buff *skb);
 51 
 52         unsigned short          flags;
 53 #define DST_HOST                0x0001
 54 #define DST_NOXFRM              0x0002
 55 #define DST_NOPOLICY            0x0004
 56 #define DST_NOCOUNT             0x0008
 57 #define DST_FAKE_RTABLE         0x0010
 58 #define DST_XFRM_TUNNEL         0x0020
 59 #define DST_XFRM_QUEUE          0x0040
 60 #define DST_METADATA            0x0080
 61 
 62         short                   error;
 63 
 64         /* A non-zero value of dst->obsolete forces by-hand validation
 65          * of the route entry.  Positive values are set by the generic
 66          * dst layer to indicate that the entry has been forcefully
 67          * destroyed.
 68          *
 69          * Negative values are used by the implementation layer code to
 70          * force invocation of the dst_ops->check() method.
 71          */
 72         short                   obsolete;
 73 #define DST_OBSOLETE_NONE       0
 74 #define DST_OBSOLETE_DEAD       2
 75 #define DST_OBSOLETE_FORCE_CHK  -1
 76 #define DST_OBSOLETE_KILL       -2
 77         unsigned short          header_len;     /* more space at head required */
 78         unsigned short          trailer_len;    /* space to reserve at tail */
 79         unsigned short          __pad3;
 80 
 81 #ifdef CONFIG_IP_ROUTE_CLASSID
 82         __u32                   tclassid;
 83 #else
 84         __u32                   __pad2;
 85 #endif
 86 
 87 #ifdef CONFIG_64BIT
 88         /*
 89          * Align __refcnt to a 64 bytes alignment
 90          * (L1_CACHE_SIZE would be too much)
 91          */
 92         long                    __pad_to_align_refcnt[2];
 93 #endif
 94         /*
 95          * __refcnt wants to be on a different cache line from
 96          * input/output/ops or performance tanks badly
 97          */
 98         atomic_t                __refcnt;       /* client references    */
 99         int                     __use;
100         unsigned long           lastuse;
101         struct lwtunnel_state   *lwtstate;
102         union {
103                 struct dst_entry        *next;
104                 struct rtable __rcu     *rt_next;
105                 struct rt6_info __rcu   *rt6_next;
106                 struct dn_route __rcu   *dn_next;
107         };
108 };
109 
110 struct dst_metrics {
111         u32             metrics[RTAX_MAX];
112         refcount_t      refcnt;
113 };
114 extern const struct dst_metrics dst_default_metrics;
115 
116 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
117 
118 #define DST_METRICS_READ_ONLY           0x1UL
119 #define DST_METRICS_REFCOUNTED          0x2UL
120 #define DST_METRICS_FLAGS               0x3UL
121 #define __DST_METRICS_PTR(Y)    \
122         ((u32 *)((Y) & ~DST_METRICS_FLAGS))
123 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
124 
125 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
126 {
127         return dst->_metrics & DST_METRICS_READ_ONLY;
128 }
129 
130 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
131 
132 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
133 {
134         unsigned long val = dst->_metrics;
135         if (!(val & DST_METRICS_READ_ONLY))
136                 __dst_destroy_metrics_generic(dst, val);
137 }
138 
139 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
140 {
141         unsigned long p = dst->_metrics;
142 
143         BUG_ON(!p);
144 
145         if (p & DST_METRICS_READ_ONLY)
146                 return dst->ops->cow_metrics(dst, p);
147         return __DST_METRICS_PTR(p);
148 }
149 
150 /* This may only be invoked before the entry has reached global
151  * visibility.
152  */
153 static inline void dst_init_metrics(struct dst_entry *dst,
154                                     const u32 *src_metrics,
155                                     bool read_only)
156 {
157         dst->_metrics = ((unsigned long) src_metrics) |
158                 (read_only ? DST_METRICS_READ_ONLY : 0);
159 }
160 
161 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
162 {
163         u32 *dst_metrics = dst_metrics_write_ptr(dest);
164 
165         if (dst_metrics) {
166                 u32 *src_metrics = DST_METRICS_PTR(src);
167 
168                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
169         }
170 }
171 
172 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
173 {
174         return DST_METRICS_PTR(dst);
175 }
176 
177 static inline u32
178 dst_metric_raw(const struct dst_entry *dst, const int metric)
179 {
180         u32 *p = DST_METRICS_PTR(dst);
181 
182         return p[metric-1];
183 }
184 
185 static inline u32
186 dst_metric(const struct dst_entry *dst, const int metric)
187 {
188         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
189                      metric == RTAX_ADVMSS ||
190                      metric == RTAX_MTU);
191         return dst_metric_raw(dst, metric);
192 }
193 
194 static inline u32
195 dst_metric_advmss(const struct dst_entry *dst)
196 {
197         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
198 
199         if (!advmss)
200                 advmss = dst->ops->default_advmss(dst);
201 
202         return advmss;
203 }
204 
205 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
206 {
207         u32 *p = dst_metrics_write_ptr(dst);
208 
209         if (p)
210                 p[metric-1] = val;
211 }
212 
213 /* Kernel-internal feature bits that are unallocated in user space. */
214 #define DST_FEATURE_ECN_CA      (1 << 31)
215 
216 #define DST_FEATURE_MASK        (DST_FEATURE_ECN_CA)
217 #define DST_FEATURE_ECN_MASK    (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN)
218 
219 static inline u32
220 dst_feature(const struct dst_entry *dst, u32 feature)
221 {
222         return dst_metric(dst, RTAX_FEATURES) & feature;
223 }
224 
225 static inline u32 dst_mtu(const struct dst_entry *dst)
226 {
227         return dst->ops->mtu(dst);
228 }
229 
230 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
231 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
232 {
233         return msecs_to_jiffies(dst_metric(dst, metric));
234 }
235 
236 static inline u32
237 dst_allfrag(const struct dst_entry *dst)
238 {
239         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
240         return ret;
241 }
242 
243 static inline int
244 dst_metric_locked(const struct dst_entry *dst, int metric)
245 {
246         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
247 }
248 
249 static inline void dst_hold(struct dst_entry *dst)
250 {
251         /*
252          * If your kernel compilation stops here, please check
253          * __pad_to_align_refcnt declaration in struct dst_entry
254          */
255         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
256         WARN_ON(atomic_inc_not_zero(&dst->__refcnt) == 0);
257 }
258 
259 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
260 {
261         if (unlikely(time != dst->lastuse)) {
262                 dst->__use++;
263                 dst->lastuse = time;
264         }
265 }
266 
267 static inline void dst_hold_and_use(struct dst_entry *dst, unsigned long time)
268 {
269         dst_hold(dst);
270         dst_use_noref(dst, time);
271 }
272 
273 static inline struct dst_entry *dst_clone(struct dst_entry *dst)
274 {
275         if (dst)
276                 dst_hold(dst);
277         return dst;
278 }
279 
280 void dst_release(struct dst_entry *dst);
281 
282 void dst_release_immediate(struct dst_entry *dst);
283 
284 static inline void refdst_drop(unsigned long refdst)
285 {
286         if (!(refdst & SKB_DST_NOREF))
287                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
288 }
289 
290 /**
291  * skb_dst_drop - drops skb dst
292  * @skb: buffer
293  *
294  * Drops dst reference count if a reference was taken.
295  */
296 static inline void skb_dst_drop(struct sk_buff *skb)
297 {
298         if (skb->_skb_refdst) {
299                 refdst_drop(skb->_skb_refdst);
300                 skb->_skb_refdst = 0UL;
301         }
302 }
303 
304 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst)
305 {
306         nskb->_skb_refdst = refdst;
307         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
308                 dst_clone(skb_dst(nskb));
309 }
310 
311 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
312 {
313         __skb_dst_copy(nskb, oskb->_skb_refdst);
314 }
315 
316 /**
317  * dst_hold_safe - Take a reference on a dst if possible
318  * @dst: pointer to dst entry
319  *
320  * This helper returns false if it could not safely
321  * take a reference on a dst.
322  */
323 static inline bool dst_hold_safe(struct dst_entry *dst)
324 {
325         return atomic_inc_not_zero(&dst->__refcnt);
326 }
327 
328 /**
329  * skb_dst_force - makes sure skb dst is refcounted
330  * @skb: buffer
331  *
332  * If dst is not yet refcounted and not destroyed, grab a ref on it.
333  */
334 static inline void skb_dst_force(struct sk_buff *skb)
335 {
336         if (skb_dst_is_noref(skb)) {
337                 struct dst_entry *dst = skb_dst(skb);
338 
339                 WARN_ON(!rcu_read_lock_held());
340                 if (!dst_hold_safe(dst))
341                         dst = NULL;
342 
343                 skb->_skb_refdst = (unsigned long)dst;
344         }
345 }
346 
347 
348 /**
349  *      __skb_tunnel_rx - prepare skb for rx reinsert
350  *      @skb: buffer
351  *      @dev: tunnel device
352  *      @net: netns for packet i/o
353  *
354  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
355  *      so make some cleanups. (no accounting done)
356  */
357 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
358                                    struct net *net)
359 {
360         skb->dev = dev;
361 
362         /*
363          * Clear hash so that we can recalulate the hash for the
364          * encapsulated packet, unless we have already determine the hash
365          * over the L4 4-tuple.
366          */
367         skb_clear_hash_if_not_l4(skb);
368         skb_set_queue_mapping(skb, 0);
369         skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
370 }
371 
372 /**
373  *      skb_tunnel_rx - prepare skb for rx reinsert
374  *      @skb: buffer
375  *      @dev: tunnel device
376  *
377  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
378  *      so make some cleanups, and perform accounting.
379  *      Note: this accounting is not SMP safe.
380  */
381 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
382                                  struct net *net)
383 {
384         /* TODO : stats should be SMP safe */
385         dev->stats.rx_packets++;
386         dev->stats.rx_bytes += skb->len;
387         __skb_tunnel_rx(skb, dev, net);
388 }
389 
390 static inline u32 dst_tclassid(const struct sk_buff *skb)
391 {
392 #ifdef CONFIG_IP_ROUTE_CLASSID
393         const struct dst_entry *dst;
394 
395         dst = skb_dst(skb);
396         if (dst)
397                 return dst->tclassid;
398 #endif
399         return 0;
400 }
401 
402 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
403 static inline int dst_discard(struct sk_buff *skb)
404 {
405         return dst_discard_out(&init_net, skb->sk, skb);
406 }
407 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref,
408                 int initial_obsolete, unsigned short flags);
409 void dst_init(struct dst_entry *dst, struct dst_ops *ops,
410               struct net_device *dev, int initial_ref, int initial_obsolete,
411               unsigned short flags);
412 struct dst_entry *dst_destroy(struct dst_entry *dst);
413 void dst_dev_put(struct dst_entry *dst);
414 
415 static inline void dst_confirm(struct dst_entry *dst)
416 {
417 }
418 
419 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
420 {
421         struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
422         return IS_ERR(n) ? NULL : n;
423 }
424 
425 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
426                                                      struct sk_buff *skb)
427 {
428         struct neighbour *n =  dst->ops->neigh_lookup(dst, skb, NULL);
429         return IS_ERR(n) ? NULL : n;
430 }
431 
432 static inline void dst_confirm_neigh(const struct dst_entry *dst,
433                                      const void *daddr)
434 {
435         if (dst->ops->confirm_neigh)
436                 dst->ops->confirm_neigh(dst, daddr);
437 }
438 
439 static inline void dst_link_failure(struct sk_buff *skb)
440 {
441         struct dst_entry *dst = skb_dst(skb);
442         if (dst && dst->ops && dst->ops->link_failure)
443                 dst->ops->link_failure(skb);
444 }
445 
446 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
447 {
448         unsigned long expires = jiffies + timeout;
449 
450         if (expires == 0)
451                 expires = 1;
452 
453         if (dst->expires == 0 || time_before(expires, dst->expires))
454                 dst->expires = expires;
455 }
456 
457 /* Output packet to network from transport.  */
458 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb)
459 {
460         return skb_dst(skb)->output(net, sk, skb);
461 }
462 
463 /* Input packet from network to transport.  */
464 static inline int dst_input(struct sk_buff *skb)
465 {
466         return skb_dst(skb)->input(skb);
467 }
468 
469 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
470 {
471         if (dst->obsolete)
472                 dst = dst->ops->check(dst, cookie);
473         return dst;
474 }
475 
476 /* Flags for xfrm_lookup flags argument. */
477 enum {
478         XFRM_LOOKUP_ICMP = 1 << 0,
479         XFRM_LOOKUP_QUEUE = 1 << 1,
480         XFRM_LOOKUP_KEEP_DST_REF = 1 << 2,
481 };
482 
483 struct flowi;
484 #ifndef CONFIG_XFRM
485 static inline struct dst_entry *xfrm_lookup(struct net *net,
486                                             struct dst_entry *dst_orig,
487                                             const struct flowi *fl,
488                                             const struct sock *sk,
489                                             int flags)
490 {
491         return dst_orig;
492 }
493 
494 static inline struct dst_entry *xfrm_lookup_route(struct net *net,
495                                                   struct dst_entry *dst_orig,
496                                                   const struct flowi *fl,
497                                                   const struct sock *sk,
498                                                   int flags)
499 {
500         return dst_orig;
501 }
502 
503 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
504 {
505         return NULL;
506 }
507 
508 #else
509 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
510                               const struct flowi *fl, const struct sock *sk,
511                               int flags);
512 
513 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
514                                     const struct flowi *fl, const struct sock *sk,
515                                     int flags);
516 
517 /* skb attached with this dst needs transformation if dst->xfrm is valid */
518 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
519 {
520         return dst->xfrm;
521 }
522 #endif
523 
524 static inline void skb_dst_update_pmtu(struct sk_buff *skb, u32 mtu)
525 {
526         struct dst_entry *dst = skb_dst(skb);
527 
528         if (dst && dst->ops->update_pmtu)
529                 dst->ops->update_pmtu(dst, NULL, skb, mtu);
530 }
531 
532 #endif /* _NET_DST_H */
533 

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