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

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  1 /*
  2  * net/dst.h    Protocol independent destination cache definitions.
  3  *
  4  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  5  *
  6  */
  7 
  8 #ifndef _NET_DST_H
  9 #define _NET_DST_H
 10 
 11 #include <net/dst_ops.h>
 12 #include <linux/netdevice.h>
 13 #include <linux/rtnetlink.h>
 14 #include <linux/rcupdate.h>
 15 #include <linux/bug.h>
 16 #include <linux/jiffies.h>
 17 #include <net/neighbour.h>
 18 #include <asm/processor.h>
 19 
 20 #define DST_GC_MIN      (HZ/10)
 21 #define DST_GC_INC      (HZ/2)
 22 #define DST_GC_MAX      (120*HZ)
 23 
 24 /* Each dst_entry has reference count and sits in some parent list(s).
 25  * When it is removed from parent list, it is "freed" (dst_free).
 26  * After this it enters dead state (dst->obsolete > 0) and if its refcnt
 27  * is zero, it can be destroyed immediately, otherwise it is added
 28  * to gc list and garbage collector periodically checks the refcnt.
 29  */
 30 
 31 struct sk_buff;
 32 
 33 struct dst_entry {
 34         struct net_device       *dev;
 35         struct rcu_head         rcu_head;
 36         struct dst_entry        *child;
 37         struct  dst_ops         *ops;
 38         unsigned long           _metrics;
 39         unsigned long           expires;
 40         struct dst_entry        *path;
 41         struct dst_entry        *from;
 42 #ifdef CONFIG_XFRM
 43         struct xfrm_state       *xfrm;
 44 #else
 45         void                    *__pad1;
 46 #endif
 47         int                     (*input)(struct sk_buff *);
 48         int                     (*output)(struct net *net, struct sock *sk, struct sk_buff *skb);
 49 
 50         unsigned short          flags;
 51 #define DST_HOST                0x0001
 52 #define DST_NOXFRM              0x0002
 53 #define DST_NOPOLICY            0x0004
 54 #define DST_NOCOUNT             0x0008
 55 #define DST_FAKE_RTABLE         0x0010
 56 #define DST_XFRM_TUNNEL         0x0020
 57 #define DST_XFRM_QUEUE          0x0040
 58 #define DST_METADATA            0x0080
 59 
 60         short                   error;
 61 
 62         /* A non-zero value of dst->obsolete forces by-hand validation
 63          * of the route entry.  Positive values are set by the generic
 64          * dst layer to indicate that the entry has been forcefully
 65          * destroyed.
 66          *
 67          * Negative values are used by the implementation layer code to
 68          * force invocation of the dst_ops->check() method.
 69          */
 70         short                   obsolete;
 71 #define DST_OBSOLETE_NONE       0
 72 #define DST_OBSOLETE_DEAD       2
 73 #define DST_OBSOLETE_FORCE_CHK  -1
 74 #define DST_OBSOLETE_KILL       -2
 75         unsigned short          header_len;     /* more space at head required */
 76         unsigned short          trailer_len;    /* space to reserve at tail */
 77         unsigned short          __pad3;
 78 
 79 #ifdef CONFIG_IP_ROUTE_CLASSID
 80         __u32                   tclassid;
 81 #else
 82         __u32                   __pad2;
 83 #endif
 84 
 85 #ifdef CONFIG_64BIT
 86         /*
 87          * Align __refcnt to a 64 bytes alignment
 88          * (L1_CACHE_SIZE would be too much)
 89          */
 90         long                    __pad_to_align_refcnt[2];
 91 #endif
 92         /*
 93          * __refcnt wants to be on a different cache line from
 94          * input/output/ops or performance tanks badly
 95          */
 96         atomic_t                __refcnt;       /* client references    */
 97         int                     __use;
 98         unsigned long           lastuse;
 99         struct lwtunnel_state   *lwtstate;
100         union {
101                 struct dst_entry        *next;
102                 struct rtable __rcu     *rt_next;
103                 struct rt6_info         *rt6_next;
104                 struct dn_route __rcu   *dn_next;
105         };
106 };
107 
108 struct dst_metrics {
109         u32             metrics[RTAX_MAX];
110         atomic_t        refcnt;
111 };
112 extern const struct dst_metrics dst_default_metrics;
113 
114 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
115 
116 #define DST_METRICS_READ_ONLY           0x1UL
117 #define DST_METRICS_REFCOUNTED          0x2UL
118 #define DST_METRICS_FLAGS               0x3UL
119 #define __DST_METRICS_PTR(Y)    \
120         ((u32 *)((Y) & ~DST_METRICS_FLAGS))
121 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
122 
123 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
124 {
125         return dst->_metrics & DST_METRICS_READ_ONLY;
126 }
127 
128 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
129 
130 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
131 {
132         unsigned long val = dst->_metrics;
133         if (!(val & DST_METRICS_READ_ONLY))
134                 __dst_destroy_metrics_generic(dst, val);
135 }
136 
137 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
138 {
139         unsigned long p = dst->_metrics;
140 
141         BUG_ON(!p);
142 
143         if (p & DST_METRICS_READ_ONLY)
144                 return dst->ops->cow_metrics(dst, p);
145         return __DST_METRICS_PTR(p);
146 }
147 
148 /* This may only be invoked before the entry has reached global
149  * visibility.
150  */
151 static inline void dst_init_metrics(struct dst_entry *dst,
152                                     const u32 *src_metrics,
153                                     bool read_only)
154 {
155         dst->_metrics = ((unsigned long) src_metrics) |
156                 (read_only ? DST_METRICS_READ_ONLY : 0);
157 }
158 
159 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
160 {
161         u32 *dst_metrics = dst_metrics_write_ptr(dest);
162 
163         if (dst_metrics) {
164                 u32 *src_metrics = DST_METRICS_PTR(src);
165 
166                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
167         }
168 }
169 
170 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
171 {
172         return DST_METRICS_PTR(dst);
173 }
174 
175 static inline u32
176 dst_metric_raw(const struct dst_entry *dst, const int metric)
177 {
178         u32 *p = DST_METRICS_PTR(dst);
179 
180         return p[metric-1];
181 }
182 
183 static inline u32
184 dst_metric(const struct dst_entry *dst, const int metric)
185 {
186         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
187                      metric == RTAX_ADVMSS ||
188                      metric == RTAX_MTU);
189         return dst_metric_raw(dst, metric);
190 }
191 
192 static inline u32
193 dst_metric_advmss(const struct dst_entry *dst)
194 {
195         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
196 
197         if (!advmss)
198                 advmss = dst->ops->default_advmss(dst);
199 
200         return advmss;
201 }
202 
203 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
204 {
205         u32 *p = dst_metrics_write_ptr(dst);
206 
207         if (p)
208                 p[metric-1] = val;
209 }
210 
211 /* Kernel-internal feature bits that are unallocated in user space. */
212 #define DST_FEATURE_ECN_CA      (1 << 31)
213 
214 #define DST_FEATURE_MASK        (DST_FEATURE_ECN_CA)
215 #define DST_FEATURE_ECN_MASK    (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN)
216 
217 static inline u32
218 dst_feature(const struct dst_entry *dst, u32 feature)
219 {
220         return dst_metric(dst, RTAX_FEATURES) & feature;
221 }
222 
223 static inline u32 dst_mtu(const struct dst_entry *dst)
224 {
225         return dst->ops->mtu(dst);
226 }
227 
228 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
229 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
230 {
231         return msecs_to_jiffies(dst_metric(dst, metric));
232 }
233 
234 static inline u32
235 dst_allfrag(const struct dst_entry *dst)
236 {
237         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
238         return ret;
239 }
240 
241 static inline int
242 dst_metric_locked(const struct dst_entry *dst, int metric)
243 {
244         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
245 }
246 
247 static inline void dst_hold(struct dst_entry *dst)
248 {
249         /*
250          * If your kernel compilation stops here, please check
251          * __pad_to_align_refcnt declaration in struct dst_entry
252          */
253         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
254         WARN_ON(atomic_inc_not_zero(&dst->__refcnt) == 0);
255 }
256 
257 static inline void dst_use(struct dst_entry *dst, unsigned long time)
258 {
259         dst_hold(dst);
260         dst->__use++;
261         dst->lastuse = time;
262 }
263 
264 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
265 {
266         dst->__use++;
267         dst->lastuse = time;
268 }
269 
270 static inline struct dst_entry *dst_clone(struct dst_entry *dst)
271 {
272         if (dst)
273                 atomic_inc(&dst->__refcnt);
274         return dst;
275 }
276 
277 void dst_release(struct dst_entry *dst);
278 
279 void dst_release_immediate(struct dst_entry *dst);
280 
281 static inline void refdst_drop(unsigned long refdst)
282 {
283         if (!(refdst & SKB_DST_NOREF))
284                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
285 }
286 
287 /**
288  * skb_dst_drop - drops skb dst
289  * @skb: buffer
290  *
291  * Drops dst reference count if a reference was taken.
292  */
293 static inline void skb_dst_drop(struct sk_buff *skb)
294 {
295         if (skb->_skb_refdst) {
296                 refdst_drop(skb->_skb_refdst);
297                 skb->_skb_refdst = 0UL;
298         }
299 }
300 
301 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst)
302 {
303         nskb->_skb_refdst = refdst;
304         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
305                 dst_clone(skb_dst(nskb));
306 }
307 
308 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
309 {
310         __skb_dst_copy(nskb, oskb->_skb_refdst);
311 }
312 
313 /**
314  * skb_dst_force - makes sure skb dst is refcounted
315  * @skb: buffer
316  *
317  * If dst is not yet refcounted, let's do it
318  */
319 static inline void skb_dst_force(struct sk_buff *skb)
320 {
321         if (skb_dst_is_noref(skb)) {
322                 WARN_ON(!rcu_read_lock_held());
323                 skb->_skb_refdst &= ~SKB_DST_NOREF;
324                 dst_clone(skb_dst(skb));
325         }
326 }
327 
328 /**
329  * dst_hold_safe - Take a reference on a dst if possible
330  * @dst: pointer to dst entry
331  *
332  * This helper returns false if it could not safely
333  * take a reference on a dst.
334  */
335 static inline bool dst_hold_safe(struct dst_entry *dst)
336 {
337         return atomic_inc_not_zero(&dst->__refcnt);
338 }
339 
340 /**
341  * skb_dst_force_safe - makes sure skb dst is refcounted
342  * @skb: buffer
343  *
344  * If dst is not yet refcounted and not destroyed, grab a ref on it.
345  */
346 static inline void skb_dst_force_safe(struct sk_buff *skb)
347 {
348         if (skb_dst_is_noref(skb)) {
349                 struct dst_entry *dst = skb_dst(skb);
350 
351                 if (!dst_hold_safe(dst))
352                         dst = NULL;
353 
354                 skb->_skb_refdst = (unsigned long)dst;
355         }
356 }
357 
358 
359 /**
360  *      __skb_tunnel_rx - prepare skb for rx reinsert
361  *      @skb: buffer
362  *      @dev: tunnel device
363  *      @net: netns for packet i/o
364  *
365  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
366  *      so make some cleanups. (no accounting done)
367  */
368 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
369                                    struct net *net)
370 {
371         skb->dev = dev;
372 
373         /*
374          * Clear hash so that we can recalulate the hash for the
375          * encapsulated packet, unless we have already determine the hash
376          * over the L4 4-tuple.
377          */
378         skb_clear_hash_if_not_l4(skb);
379         skb_set_queue_mapping(skb, 0);
380         skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
381 }
382 
383 /**
384  *      skb_tunnel_rx - prepare skb for rx reinsert
385  *      @skb: buffer
386  *      @dev: tunnel device
387  *
388  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
389  *      so make some cleanups, and perform accounting.
390  *      Note: this accounting is not SMP safe.
391  */
392 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
393                                  struct net *net)
394 {
395         /* TODO : stats should be SMP safe */
396         dev->stats.rx_packets++;
397         dev->stats.rx_bytes += skb->len;
398         __skb_tunnel_rx(skb, dev, net);
399 }
400 
401 static inline u32 dst_tclassid(const struct sk_buff *skb)
402 {
403 #ifdef CONFIG_IP_ROUTE_CLASSID
404         const struct dst_entry *dst;
405 
406         dst = skb_dst(skb);
407         if (dst)
408                 return dst->tclassid;
409 #endif
410         return 0;
411 }
412 
413 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
414 static inline int dst_discard(struct sk_buff *skb)
415 {
416         return dst_discard_out(&init_net, skb->sk, skb);
417 }
418 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref,
419                 int initial_obsolete, unsigned short flags);
420 void dst_init(struct dst_entry *dst, struct dst_ops *ops,
421               struct net_device *dev, int initial_ref, int initial_obsolete,
422               unsigned short flags);
423 struct dst_entry *dst_destroy(struct dst_entry *dst);
424 void dst_dev_put(struct dst_entry *dst);
425 
426 static inline void dst_confirm(struct dst_entry *dst)
427 {
428 }
429 
430 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
431 {
432         struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
433         return IS_ERR(n) ? NULL : n;
434 }
435 
436 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
437                                                      struct sk_buff *skb)
438 {
439         struct neighbour *n =  dst->ops->neigh_lookup(dst, skb, NULL);
440         return IS_ERR(n) ? NULL : n;
441 }
442 
443 static inline void dst_confirm_neigh(const struct dst_entry *dst,
444                                      const void *daddr)
445 {
446         if (dst->ops->confirm_neigh)
447                 dst->ops->confirm_neigh(dst, daddr);
448 }
449 
450 static inline void dst_link_failure(struct sk_buff *skb)
451 {
452         struct dst_entry *dst = skb_dst(skb);
453         if (dst && dst->ops && dst->ops->link_failure)
454                 dst->ops->link_failure(skb);
455 }
456 
457 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
458 {
459         unsigned long expires = jiffies + timeout;
460 
461         if (expires == 0)
462                 expires = 1;
463 
464         if (dst->expires == 0 || time_before(expires, dst->expires))
465                 dst->expires = expires;
466 }
467 
468 /* Output packet to network from transport.  */
469 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb)
470 {
471         return skb_dst(skb)->output(net, sk, skb);
472 }
473 
474 /* Input packet from network to transport.  */
475 static inline int dst_input(struct sk_buff *skb)
476 {
477         return skb_dst(skb)->input(skb);
478 }
479 
480 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
481 {
482         if (dst->obsolete)
483                 dst = dst->ops->check(dst, cookie);
484         return dst;
485 }
486 
487 /* Flags for xfrm_lookup flags argument. */
488 enum {
489         XFRM_LOOKUP_ICMP = 1 << 0,
490         XFRM_LOOKUP_QUEUE = 1 << 1,
491         XFRM_LOOKUP_KEEP_DST_REF = 1 << 2,
492 };
493 
494 struct flowi;
495 #ifndef CONFIG_XFRM
496 static inline struct dst_entry *xfrm_lookup(struct net *net,
497                                             struct dst_entry *dst_orig,
498                                             const struct flowi *fl,
499                                             const struct sock *sk,
500                                             int flags)
501 {
502         return dst_orig;
503 }
504 
505 static inline struct dst_entry *xfrm_lookup_route(struct net *net,
506                                                   struct dst_entry *dst_orig,
507                                                   const struct flowi *fl,
508                                                   const struct sock *sk,
509                                                   int flags)
510 {
511         return dst_orig;
512 }
513 
514 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
515 {
516         return NULL;
517 }
518 
519 #else
520 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
521                               const struct flowi *fl, const struct sock *sk,
522                               int flags);
523 
524 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
525                                     const struct flowi *fl, const struct sock *sk,
526                                     int flags);
527 
528 /* skb attached with this dst needs transformation if dst->xfrm is valid */
529 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
530 {
531         return dst->xfrm;
532 }
533 #endif
534 
535 #endif /* _NET_DST_H */
536 

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