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 <linux/rcuref.h>
20 #include <net/neighbour.h>
21 #include <asm/processor.h>
22 #include <linux/indirect_call_wrapper.h>
23
24 struct sk_buff;
25
26 struct dst_entry {
27 struct net_device *dev;
28 struct dst_ops *ops;
29 unsigned long _metrics;
30 unsigned long expires;
31 #ifdef CONFIG_XFRM
32 struct xfrm_state *xfrm;
33 #else
34 void *__pad1;
35 #endif
36 int (*input)(struct sk_buff *);
37 int (*output)(struct net *net, struct sock *sk, struct sk_buff *skb);
38
39 unsigned short flags;
40 #define DST_NOXFRM 0x0002
41 #define DST_NOPOLICY 0x0004
42 #define DST_NOCOUNT 0x0008
43 #define DST_FAKE_RTABLE 0x0010
44 #define DST_XFRM_TUNNEL 0x0020
45 #define DST_XFRM_QUEUE 0x0040
46 #define DST_METADATA 0x0080
47
48 /* A non-zero value of dst->obsolete forces by-hand validation
49 * of the route entry. Positive values are set by the generic
50 * dst layer to indicate that the entry has been forcefully
51 * destroyed.
52 *
53 * Negative values are used by the implementation layer code to
54 * force invocation of the dst_ops->check() method.
55 */
56 short obsolete;
57 #define DST_OBSOLETE_NONE 0
58 #define DST_OBSOLETE_DEAD 2
59 #define DST_OBSOLETE_FORCE_CHK -1
60 #define DST_OBSOLETE_KILL -2
61 unsigned short header_len; /* more space at head required */
62 unsigned short trailer_len; /* space to reserve at tail */
63
64 /*
65 * __rcuref wants to be on a different cache line from
66 * input/output/ops or performance tanks badly
67 */
68 #ifdef CONFIG_64BIT
69 rcuref_t __rcuref; /* 64-bit offset 64 */
70 #endif
71 int __use;
72 unsigned long lastuse;
73 struct rcu_head rcu_head;
74 short error;
75 short __pad;
76 __u32 tclassid;
77 #ifndef CONFIG_64BIT
78 struct lwtunnel_state *lwtstate;
79 rcuref_t __rcuref; /* 32-bit offset 64 */
80 #endif
81 netdevice_tracker dev_tracker;
82
83 /*
84 * Used by rtable and rt6_info. Moves lwtstate into the next cache
85 * line on 64bit so that lwtstate does not cause false sharing with
86 * __rcuref under contention of __rcuref. This also puts the
87 * frequently accessed members of rtable and rt6_info out of the
88 * __rcuref cache line.
89 */
90 struct list_head rt_uncached;
91 struct uncached_list *rt_uncached_list;
92 #ifdef CONFIG_64BIT
93 struct lwtunnel_state *lwtstate;
94 #endif
95 };
96
97 struct dst_metrics {
98 u32 metrics[RTAX_MAX];
99 refcount_t refcnt;
100 } __aligned(4); /* Low pointer bits contain DST_METRICS_FLAGS */
101 extern const struct dst_metrics dst_default_metrics;
102
103 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
104
105 #define DST_METRICS_READ_ONLY 0x1UL
106 #define DST_METRICS_REFCOUNTED 0x2UL
107 #define DST_METRICS_FLAGS 0x3UL
108 #define __DST_METRICS_PTR(Y) \
109 ((u32 *)((Y) & ~DST_METRICS_FLAGS))
110 #define DST_METRICS_PTR(X) __DST_METRICS_PTR((X)->_metrics)
111
112 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
113 {
114 return dst->_metrics & DST_METRICS_READ_ONLY;
115 }
116
117 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
118
119 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
120 {
121 unsigned long val = dst->_metrics;
122 if (!(val & DST_METRICS_READ_ONLY))
123 __dst_destroy_metrics_generic(dst, val);
124 }
125
126 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
127 {
128 unsigned long p = dst->_metrics;
129
130 BUG_ON(!p);
131
132 if (p & DST_METRICS_READ_ONLY)
133 return dst->ops->cow_metrics(dst, p);
134 return __DST_METRICS_PTR(p);
135 }
136
137 /* This may only be invoked before the entry has reached global
138 * visibility.
139 */
140 static inline void dst_init_metrics(struct dst_entry *dst,
141 const u32 *src_metrics,
142 bool read_only)
143 {
144 dst->_metrics = ((unsigned long) src_metrics) |
145 (read_only ? DST_METRICS_READ_ONLY : 0);
146 }
147
148 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
149 {
150 u32 *dst_metrics = dst_metrics_write_ptr(dest);
151
152 if (dst_metrics) {
153 u32 *src_metrics = DST_METRICS_PTR(src);
154
155 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
156 }
157 }
158
159 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
160 {
161 return DST_METRICS_PTR(dst);
162 }
163
164 static inline u32
165 dst_metric_raw(const struct dst_entry *dst, const int metric)
166 {
167 u32 *p = DST_METRICS_PTR(dst);
168
169 return p[metric-1];
170 }
171
172 static inline u32
173 dst_metric(const struct dst_entry *dst, const int metric)
174 {
175 WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
176 metric == RTAX_ADVMSS ||
177 metric == RTAX_MTU);
178 return dst_metric_raw(dst, metric);
179 }
180
181 static inline u32
182 dst_metric_advmss(const struct dst_entry *dst)
183 {
184 u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
185
186 if (!advmss)
187 advmss = dst->ops->default_advmss(dst);
188
189 return advmss;
190 }
191
192 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
193 {
194 u32 *p = dst_metrics_write_ptr(dst);
195
196 if (p)
197 p[metric-1] = val;
198 }
199
200 /* Kernel-internal feature bits that are unallocated in user space. */
201 #define DST_FEATURE_ECN_CA (1U << 31)
202
203 #define DST_FEATURE_MASK (DST_FEATURE_ECN_CA)
204 #define DST_FEATURE_ECN_MASK (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN)
205
206 static inline u32
207 dst_feature(const struct dst_entry *dst, u32 feature)
208 {
209 return dst_metric(dst, RTAX_FEATURES) & feature;
210 }
211
212 INDIRECT_CALLABLE_DECLARE(unsigned int ip6_mtu(const struct dst_entry *));
213 INDIRECT_CALLABLE_DECLARE(unsigned int ipv4_mtu(const struct dst_entry *));
214 static inline u32 dst_mtu(const struct dst_entry *dst)
215 {
216 return INDIRECT_CALL_INET(dst->ops->mtu, ip6_mtu, ipv4_mtu, dst);
217 }
218
219 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
220 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
221 {
222 return msecs_to_jiffies(dst_metric(dst, metric));
223 }
224
225 static inline int
226 dst_metric_locked(const struct dst_entry *dst, int metric)
227 {
228 return dst_metric(dst, RTAX_LOCK) & (1 << metric);
229 }
230
231 static inline void dst_hold(struct dst_entry *dst)
232 {
233 /*
234 * If your kernel compilation stops here, please check
235 * the placement of __rcuref in struct dst_entry
236 */
237 BUILD_BUG_ON(offsetof(struct dst_entry, __rcuref) & 63);
238 WARN_ON(!rcuref_get(&dst->__rcuref));
239 }
240
241 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
242 {
243 if (unlikely(time != dst->lastuse)) {
244 dst->__use++;
245 dst->lastuse = time;
246 }
247 }
248
249 static inline struct dst_entry *dst_clone(struct dst_entry *dst)
250 {
251 if (dst)
252 dst_hold(dst);
253 return dst;
254 }
255
256 void dst_release(struct dst_entry *dst);
257
258 void dst_release_immediate(struct dst_entry *dst);
259
260 static inline void refdst_drop(unsigned long refdst)
261 {
262 if (!(refdst & SKB_DST_NOREF))
263 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
264 }
265
266 /**
267 * skb_dst_drop - drops skb dst
268 * @skb: buffer
269 *
270 * Drops dst reference count if a reference was taken.
271 */
272 static inline void skb_dst_drop(struct sk_buff *skb)
273 {
274 if (skb->_skb_refdst) {
275 refdst_drop(skb->_skb_refdst);
276 skb->_skb_refdst = 0UL;
277 }
278 }
279
280 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst)
281 {
282 nskb->slow_gro |= !!refdst;
283 nskb->_skb_refdst = refdst;
284 if (!(nskb->_skb_refdst & SKB_DST_NOREF))
285 dst_clone(skb_dst(nskb));
286 }
287
288 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
289 {
290 __skb_dst_copy(nskb, oskb->_skb_refdst);
291 }
292
293 /**
294 * dst_hold_safe - Take a reference on a dst if possible
295 * @dst: pointer to dst entry
296 *
297 * This helper returns false if it could not safely
298 * take a reference on a dst.
299 */
300 static inline bool dst_hold_safe(struct dst_entry *dst)
301 {
302 return rcuref_get(&dst->__rcuref);
303 }
304
305 /**
306 * skb_dst_force - makes sure skb dst is refcounted
307 * @skb: buffer
308 *
309 * If dst is not yet refcounted and not destroyed, grab a ref on it.
310 * Returns true if dst is refcounted.
311 */
312 static inline bool skb_dst_force(struct sk_buff *skb)
313 {
314 if (skb_dst_is_noref(skb)) {
315 struct dst_entry *dst = skb_dst(skb);
316
317 WARN_ON(!rcu_read_lock_held());
318 if (!dst_hold_safe(dst))
319 dst = NULL;
320
321 skb->_skb_refdst = (unsigned long)dst;
322 skb->slow_gro |= !!dst;
323 }
324
325 return skb->_skb_refdst != 0UL;
326 }
327
328
329 /**
330 * __skb_tunnel_rx - prepare skb for rx reinsert
331 * @skb: buffer
332 * @dev: tunnel device
333 * @net: netns for packet i/o
334 *
335 * After decapsulation, packet is going to re-enter (netif_rx()) our stack,
336 * so make some cleanups. (no accounting done)
337 */
338 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
339 struct net *net)
340 {
341 skb->dev = dev;
342
343 /*
344 * Clear hash so that we can recalulate the hash for the
345 * encapsulated packet, unless we have already determine the hash
346 * over the L4 4-tuple.
347 */
348 skb_clear_hash_if_not_l4(skb);
349 skb_set_queue_mapping(skb, 0);
350 skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
351 }
352
353 /**
354 * skb_tunnel_rx - prepare skb for rx reinsert
355 * @skb: buffer
356 * @dev: tunnel device
357 * @net: netns for packet i/o
358 *
359 * After decapsulation, packet is going to re-enter (netif_rx()) our stack,
360 * so make some cleanups, and perform accounting.
361 * Note: this accounting is not SMP safe.
362 */
363 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
364 struct net *net)
365 {
366 DEV_STATS_INC(dev, rx_packets);
367 DEV_STATS_ADD(dev, rx_bytes, skb->len);
368 __skb_tunnel_rx(skb, dev, net);
369 }
370
371 static inline u32 dst_tclassid(const struct sk_buff *skb)
372 {
373 #ifdef CONFIG_IP_ROUTE_CLASSID
374 const struct dst_entry *dst;
375
376 dst = skb_dst(skb);
377 if (dst)
378 return dst->tclassid;
379 #endif
380 return 0;
381 }
382
383 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
384 static inline int dst_discard(struct sk_buff *skb)
385 {
386 return dst_discard_out(&init_net, skb->sk, skb);
387 }
388 void *dst_alloc(struct dst_ops *ops, struct net_device *dev,
389 int initial_obsolete, unsigned short flags);
390 void dst_init(struct dst_entry *dst, struct dst_ops *ops,
391 struct net_device *dev, int initial_obsolete,
392 unsigned short flags);
393 void dst_dev_put(struct dst_entry *dst);
394
395 static inline void dst_confirm(struct dst_entry *dst)
396 {
397 }
398
399 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
400 {
401 struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
402 return IS_ERR(n) ? NULL : n;
403 }
404
405 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
406 struct sk_buff *skb)
407 {
408 struct neighbour *n;
409
410 if (WARN_ON_ONCE(!dst->ops->neigh_lookup))
411 return NULL;
412
413 n = dst->ops->neigh_lookup(dst, skb, NULL);
414
415 return IS_ERR(n) ? NULL : n;
416 }
417
418 static inline void dst_confirm_neigh(const struct dst_entry *dst,
419 const void *daddr)
420 {
421 if (dst->ops->confirm_neigh)
422 dst->ops->confirm_neigh(dst, daddr);
423 }
424
425 static inline void dst_link_failure(struct sk_buff *skb)
426 {
427 struct dst_entry *dst = skb_dst(skb);
428 if (dst && dst->ops && dst->ops->link_failure)
429 dst->ops->link_failure(skb);
430 }
431
432 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
433 {
434 unsigned long expires = jiffies + timeout;
435
436 if (expires == 0)
437 expires = 1;
438
439 if (dst->expires == 0 || time_before(expires, dst->expires))
440 dst->expires = expires;
441 }
442
443 INDIRECT_CALLABLE_DECLARE(int ip6_output(struct net *, struct sock *,
444 struct sk_buff *));
445 INDIRECT_CALLABLE_DECLARE(int ip_output(struct net *, struct sock *,
446 struct sk_buff *));
447 /* Output packet to network from transport. */
448 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb)
449 {
450 return INDIRECT_CALL_INET(skb_dst(skb)->output,
451 ip6_output, ip_output,
452 net, sk, skb);
453 }
454
455 INDIRECT_CALLABLE_DECLARE(int ip6_input(struct sk_buff *));
456 INDIRECT_CALLABLE_DECLARE(int ip_local_deliver(struct sk_buff *));
457 /* Input packet from network to transport. */
458 static inline int dst_input(struct sk_buff *skb)
459 {
460 return INDIRECT_CALL_INET(skb_dst(skb)->input,
461 ip6_input, ip_local_deliver, skb);
462 }
463
464 INDIRECT_CALLABLE_DECLARE(struct dst_entry *ip6_dst_check(struct dst_entry *,
465 u32));
466 INDIRECT_CALLABLE_DECLARE(struct dst_entry *ipv4_dst_check(struct dst_entry *,
467 u32));
468 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
469 {
470 if (dst->obsolete)
471 dst = INDIRECT_CALL_INET(dst->ops->check, ip6_dst_check,
472 ipv4_dst_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 *
495 xfrm_lookup_with_ifid(struct net *net, struct dst_entry *dst_orig,
496 const struct flowi *fl, const struct sock *sk,
497 int flags, u32 if_id)
498 {
499 return dst_orig;
500 }
501
502 static inline struct dst_entry *xfrm_lookup_route(struct net *net,
503 struct dst_entry *dst_orig,
504 const struct flowi *fl,
505 const struct sock *sk,
506 int flags)
507 {
508 return dst_orig;
509 }
510
511 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
512 {
513 return NULL;
514 }
515
516 #else
517 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
518 const struct flowi *fl, const struct sock *sk,
519 int flags);
520
521 struct dst_entry *xfrm_lookup_with_ifid(struct net *net,
522 struct dst_entry *dst_orig,
523 const struct flowi *fl,
524 const struct sock *sk, int flags,
525 u32 if_id);
526
527 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
528 const struct flowi *fl, const struct sock *sk,
529 int flags);
530
531 /* skb attached with this dst needs transformation if dst->xfrm is valid */
532 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
533 {
534 return dst->xfrm;
535 }
536 #endif
537
538 static inline void skb_dst_update_pmtu(struct sk_buff *skb, u32 mtu)
539 {
540 struct dst_entry *dst = skb_dst(skb);
541
542 if (dst && dst->ops->update_pmtu)
543 dst->ops->update_pmtu(dst, NULL, skb, mtu, true);
544 }
545
546 /* update dst pmtu but not do neighbor confirm */
547 static inline void skb_dst_update_pmtu_no_confirm(struct sk_buff *skb, u32 mtu)
548 {
549 struct dst_entry *dst = skb_dst(skb);
550
551 if (dst && dst->ops->update_pmtu)
552 dst->ops->update_pmtu(dst, NULL, skb, mtu, false);
553 }
554
555 struct dst_entry *dst_blackhole_check(struct dst_entry *dst, u32 cookie);
556 void dst_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
557 struct sk_buff *skb, u32 mtu, bool confirm_neigh);
558 void dst_blackhole_redirect(struct dst_entry *dst, struct sock *sk,
559 struct sk_buff *skb);
560 u32 *dst_blackhole_cow_metrics(struct dst_entry *dst, unsigned long old);
561 struct neighbour *dst_blackhole_neigh_lookup(const struct dst_entry *dst,
562 struct sk_buff *skb,
563 const void *daddr);
564 unsigned int dst_blackhole_mtu(const struct dst_entry *dst);
565
566 #endif /* _NET_DST_H */
567
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