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
24struct sk_buff;
25
26struct dst_entry {
27 union {
28 struct net_device *dev;
29 struct net_device __rcu *dev_rcu;
30 };
31 struct dst_ops *ops;
32 unsigned long _metrics;
33 unsigned long expires;
34#ifdef CONFIG_XFRM
35 struct xfrm_state *xfrm;
36#else
37 void *__pad1;
38#endif
39 int (*input)(struct sk_buff *);
40 int (*output)(struct net *net, struct sock *sk, struct sk_buff *skb);
41
42 unsigned short flags;
43#define DST_NOXFRM 0x0002
44#define DST_NOPOLICY 0x0004
45#define DST_NOCOUNT 0x0008
46#define DST_FAKE_RTABLE 0x0010
47#define DST_XFRM_TUNNEL 0x0020
48#define DST_XFRM_QUEUE 0x0040
49#define DST_METADATA 0x0080
50
51 /* A non-zero value of dst->obsolete forces by-hand validation
52 * of the route entry. Positive values are set by the generic
53 * dst layer to indicate that the entry has been forcefully
54 * destroyed.
55 *
56 * Negative values are used by the implementation layer code to
57 * force invocation of the dst_ops->check() method.
58 */
59 short obsolete;
60#define DST_OBSOLETE_NONE 0
61#define DST_OBSOLETE_DEAD 2
62#define DST_OBSOLETE_FORCE_CHK -1
63#define DST_OBSOLETE_KILL -2
64 unsigned short header_len; /* more space at head required */
65 unsigned short trailer_len; /* space to reserve at tail */
66
67 /*
68 * __rcuref wants to be on a different cache line from
69 * input/output/ops or performance tanks badly
70 */
71#ifdef CONFIG_64BIT
72 rcuref_t __rcuref; /* 64-bit offset 64 */
73#endif
74 int __use;
75 unsigned long lastuse;
76 struct rcu_head rcu_head;
77 short error;
78 short __pad;
79 __u32 tclassid;
80#ifndef CONFIG_64BIT
81 struct lwtunnel_state *lwtstate;
82 rcuref_t __rcuref; /* 32-bit offset 64 */
83#endif
84 netdevice_tracker dev_tracker;
85
86 /*
87 * Used by rtable and rt6_info. Moves lwtstate into the next cache
88 * line on 64bit so that lwtstate does not cause false sharing with
89 * __rcuref under contention of __rcuref. This also puts the
90 * frequently accessed members of rtable and rt6_info out of the
91 * __rcuref cache line.
92 */
93 struct list_head rt_uncached;
94 struct uncached_list *rt_uncached_list;
95#ifdef CONFIG_64BIT
96 struct lwtunnel_state *lwtstate;
97#endif
98};
99
100struct dst_metrics {
101 u32 metrics[RTAX_MAX];
102 refcount_t refcnt;
103} __aligned(4); /* Low pointer bits contain DST_METRICS_FLAGS */
104extern const struct dst_metrics dst_default_metrics;
105
106u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
107
108#define DST_METRICS_READ_ONLY 0x1UL
109#define DST_METRICS_REFCOUNTED 0x2UL
110#define DST_METRICS_FLAGS 0x3UL
111#define __DST_METRICS_PTR(Y) \
112 ((u32 *)((Y) & ~DST_METRICS_FLAGS))
113#define DST_METRICS_PTR(X) __DST_METRICS_PTR((X)->_metrics)
114
115static inline bool dst_metrics_read_only(const struct dst_entry *dst)
116{
117 return dst->_metrics & DST_METRICS_READ_ONLY;
118}
119
120void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
121
122static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
123{
124 unsigned long val = dst->_metrics;
125 if (!(val & DST_METRICS_READ_ONLY))
126 __dst_destroy_metrics_generic(dst, old: val);
127}
128
129static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
130{
131 unsigned long p = dst->_metrics;
132
133 BUG_ON(!p);
134
135 if (p & DST_METRICS_READ_ONLY)
136 return dst->ops->cow_metrics(dst, p);
137 return __DST_METRICS_PTR(p);
138}
139
140/* This may only be invoked before the entry has reached global
141 * visibility.
142 */
143static inline void dst_init_metrics(struct dst_entry *dst,
144 const u32 *src_metrics,
145 bool read_only)
146{
147 dst->_metrics = ((unsigned long) src_metrics) |
148 (read_only ? DST_METRICS_READ_ONLY : 0);
149}
150
151static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
152{
153 u32 *dst_metrics = dst_metrics_write_ptr(dst: dest);
154
155 if (dst_metrics) {
156 u32 *src_metrics = DST_METRICS_PTR(src);
157
158 memcpy(to: dst_metrics, from: src_metrics, RTAX_MAX * sizeof(u32));
159 }
160}
161
162static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
163{
164 return DST_METRICS_PTR(dst);
165}
166
167static inline u32
168dst_metric_raw(const struct dst_entry *dst, const int metric)
169{
170 u32 *p = DST_METRICS_PTR(dst);
171
172 return p[metric-1];
173}
174
175static inline u32
176dst_metric(const struct dst_entry *dst, const int metric)
177{
178 WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
179 metric == RTAX_ADVMSS ||
180 metric == RTAX_MTU);
181 return dst_metric_raw(dst, metric);
182}
183
184static inline u32
185dst_metric_advmss(const struct dst_entry *dst)
186{
187 u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
188
189 if (!advmss)
190 advmss = dst->ops->default_advmss(dst);
191
192 return advmss;
193}
194
195static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
196{
197 u32 *p = dst_metrics_write_ptr(dst);
198
199 if (p)
200 p[metric-1] = val;
201}
202
203/* Kernel-internal feature bits that are unallocated in user space. */
204#define DST_FEATURE_ECN_CA (1U << 31)
205
206#define DST_FEATURE_MASK (DST_FEATURE_ECN_CA)
207#define DST_FEATURE_ECN_MASK (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN)
208
209static inline u32
210dst_feature(const struct dst_entry *dst, u32 feature)
211{
212 return dst_metric(dst, RTAX_FEATURES) & feature;
213}
214
215INDIRECT_CALLABLE_DECLARE(unsigned int ip6_mtu(const struct dst_entry *));
216INDIRECT_CALLABLE_DECLARE(unsigned int ipv4_mtu(const struct dst_entry *));
217static inline u32 dst_mtu(const struct dst_entry *dst)
218{
219 return INDIRECT_CALL_INET(dst->ops->mtu, ip6_mtu, ipv4_mtu, dst);
220}
221
222/* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
223static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
224{
225 return msecs_to_jiffies(m: dst_metric(dst, metric));
226}
227
228static inline int
229dst_metric_locked(const struct dst_entry *dst, int metric)
230{
231 return dst_metric(dst, RTAX_LOCK) & (1 << metric);
232}
233
234static inline void dst_hold(struct dst_entry *dst)
235{
236 /*
237 * If your kernel compilation stops here, please check
238 * the placement of __rcuref in struct dst_entry
239 */
240 BUILD_BUG_ON(offsetof(struct dst_entry, __rcuref) & 63);
241 WARN_ON(!rcuref_get(&dst->__rcuref));
242}
243
244static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
245{
246 if (unlikely(time != READ_ONCE(dst->lastuse))) {
247 dst->__use++;
248 WRITE_ONCE(dst->lastuse, time);
249 }
250}
251
252static inline struct dst_entry *dst_clone(struct dst_entry *dst)
253{
254 if (dst)
255 dst_hold(dst);
256 return dst;
257}
258
259void dst_release(struct dst_entry *dst);
260
261void dst_release_immediate(struct dst_entry *dst);
262
263static inline void refdst_drop(unsigned long refdst)
264{
265 if (!(refdst & SKB_DST_NOREF))
266 dst_release(dst: (struct dst_entry *)(refdst & SKB_DST_PTRMASK));
267}
268
269/**
270 * skb_dst_drop - drops skb dst
271 * @skb: buffer
272 *
273 * Drops dst reference count if a reference was taken.
274 */
275static inline void skb_dst_drop(struct sk_buff *skb)
276{
277 if (skb->_skb_refdst) {
278 refdst_drop(refdst: skb->_skb_refdst);
279 skb->_skb_refdst = 0UL;
280 }
281}
282
283static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst)
284{
285 nskb->slow_gro |= !!refdst;
286 nskb->_skb_refdst = refdst;
287 if (!(nskb->_skb_refdst & SKB_DST_NOREF))
288 dst_clone(dst: skb_dst(skb: nskb));
289}
290
291static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
292{
293 __skb_dst_copy(nskb, refdst: oskb->_skb_refdst);
294}
295
296/**
297 * dst_hold_safe - Take a reference on a dst if possible
298 * @dst: pointer to dst entry
299 *
300 * This helper returns false if it could not safely
301 * take a reference on a dst.
302 */
303static inline bool dst_hold_safe(struct dst_entry *dst)
304{
305 return rcuref_get(ref: &dst->__rcuref);
306}
307
308/**
309 * skb_dst_force - makes sure skb dst is refcounted
310 * @skb: buffer
311 *
312 * If dst is not yet refcounted and not destroyed, grab a ref on it.
313 * Returns: true if dst is refcounted.
314 */
315static inline bool skb_dst_force(struct sk_buff *skb)
316{
317 if (skb_dst_is_noref(skb)) {
318 struct dst_entry *dst = skb_dst(skb);
319
320 WARN_ON(!rcu_read_lock_held());
321 if (!dst_hold_safe(dst))
322 dst = NULL;
323
324 skb->_skb_refdst = (unsigned long)dst;
325 skb->slow_gro |= !!dst;
326 }
327
328 return skb->_skb_refdst != 0UL;
329}
330
331
332/**
333 * __skb_tunnel_rx - prepare skb for rx reinsert
334 * @skb: buffer
335 * @dev: tunnel device
336 * @net: netns for packet i/o
337 *
338 * After decapsulation, packet is going to re-enter (netif_rx()) our stack,
339 * so make some cleanups. (no accounting done)
340 */
341static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
342 struct net *net)
343{
344 skb->dev = dev;
345
346 /*
347 * Clear hash so that we can recalculate the hash for the
348 * encapsulated packet, unless we have already determine the hash
349 * over the L4 4-tuple.
350 */
351 skb_clear_hash_if_not_l4(skb);
352 skb_set_queue_mapping(skb, queue_mapping: 0);
353 skb_scrub_packet(skb, xnet: !net_eq(net1: net, net2: dev_net(dev)));
354}
355
356/**
357 * skb_tunnel_rx - prepare skb for rx reinsert
358 * @skb: buffer
359 * @dev: tunnel device
360 * @net: netns for packet i/o
361 *
362 * After decapsulation, packet is going to re-enter (netif_rx()) our stack,
363 * so make some cleanups, and perform accounting.
364 * Note: this accounting is not SMP safe.
365 */
366static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
367 struct net *net)
368{
369 DEV_STATS_INC(dev, rx_packets);
370 DEV_STATS_ADD(dev, rx_bytes, skb->len);
371 __skb_tunnel_rx(skb, dev, net);
372}
373
374static inline u32 dst_tclassid(const struct sk_buff *skb)
375{
376#ifdef CONFIG_IP_ROUTE_CLASSID
377 const struct dst_entry *dst;
378
379 dst = skb_dst(skb);
380 if (dst)
381 return dst->tclassid;
382#endif
383 return 0;
384}
385
386int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
387static inline int dst_discard(struct sk_buff *skb)
388{
389 return dst_discard_out(net: &init_net, sk: skb->sk, skb);
390}
391void *dst_alloc(struct dst_ops *ops, struct net_device *dev,
392 int initial_obsolete, unsigned short flags);
393void dst_init(struct dst_entry *dst, struct dst_ops *ops,
394 struct net_device *dev, int initial_obsolete,
395 unsigned short flags);
396void dst_dev_put(struct dst_entry *dst);
397
398static inline void dst_confirm(struct dst_entry *dst)
399{
400}
401
402static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
403{
404 struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
405 return IS_ERR(ptr: n) ? NULL : n;
406}
407
408static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
409 struct sk_buff *skb)
410{
411 struct neighbour *n;
412
413 if (WARN_ON_ONCE(!dst->ops->neigh_lookup))
414 return NULL;
415
416 n = dst->ops->neigh_lookup(dst, skb, NULL);
417
418 return IS_ERR(ptr: n) ? NULL : n;
419}
420
421static inline void dst_confirm_neigh(const struct dst_entry *dst,
422 const void *daddr)
423{
424 if (dst->ops->confirm_neigh)
425 dst->ops->confirm_neigh(dst, daddr);
426}
427
428static inline void dst_link_failure(struct sk_buff *skb)
429{
430 struct dst_entry *dst = skb_dst(skb);
431 if (dst && dst->ops && dst->ops->link_failure)
432 dst->ops->link_failure(skb);
433}
434
435static inline void dst_set_expires(struct dst_entry *dst, int timeout)
436{
437 unsigned long old, expires = jiffies + timeout;
438
439 if (expires == 0)
440 expires = 1;
441
442 old = READ_ONCE(dst->expires);
443
444 if (!old || time_before(expires, old))
445 WRITE_ONCE(dst->expires, expires);
446}
447
448static inline unsigned int dst_dev_overhead(struct dst_entry *dst,
449 struct sk_buff *skb)
450{
451 if (likely(dst))
452 return LL_RESERVED_SPACE(dst->dev);
453
454 return skb->mac_len;
455}
456
457INDIRECT_CALLABLE_DECLARE(int ip6_output(struct net *, struct sock *,
458 struct sk_buff *));
459INDIRECT_CALLABLE_DECLARE(int ip_output(struct net *, struct sock *,
460 struct sk_buff *));
461/* Output packet to network from transport. */
462static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb)
463{
464 return INDIRECT_CALL_INET(READ_ONCE(skb_dst(skb)->output),
465 ip6_output, ip_output,
466 net, sk, skb);
467}
468
469INDIRECT_CALLABLE_DECLARE(int ip6_input(struct sk_buff *));
470INDIRECT_CALLABLE_DECLARE(int ip_local_deliver(struct sk_buff *));
471/* Input packet from network to transport. */
472static inline int dst_input(struct sk_buff *skb)
473{
474 return INDIRECT_CALL_INET(READ_ONCE(skb_dst(skb)->input),
475 ip6_input, ip_local_deliver, skb);
476}
477
478INDIRECT_CALLABLE_DECLARE(struct dst_entry *ip6_dst_check(struct dst_entry *,
479 u32));
480INDIRECT_CALLABLE_DECLARE(struct dst_entry *ipv4_dst_check(struct dst_entry *,
481 u32));
482static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
483{
484 if (READ_ONCE(dst->obsolete))
485 dst = INDIRECT_CALL_INET(dst->ops->check, ip6_dst_check,
486 ipv4_dst_check, dst, cookie);
487 return dst;
488}
489
490/* Flags for xfrm_lookup flags argument. */
491enum {
492 XFRM_LOOKUP_ICMP = 1 << 0,
493 XFRM_LOOKUP_QUEUE = 1 << 1,
494 XFRM_LOOKUP_KEEP_DST_REF = 1 << 2,
495};
496
497struct flowi;
498#ifndef CONFIG_XFRM
499static inline struct dst_entry *xfrm_lookup(struct net *net,
500 struct dst_entry *dst_orig,
501 const struct flowi *fl,
502 const struct sock *sk,
503 int flags)
504{
505 return dst_orig;
506}
507
508static inline struct dst_entry *
509xfrm_lookup_with_ifid(struct net *net, struct dst_entry *dst_orig,
510 const struct flowi *fl, const struct sock *sk,
511 int flags, u32 if_id)
512{
513 return dst_orig;
514}
515
516static inline struct dst_entry *xfrm_lookup_route(struct net *net,
517 struct dst_entry *dst_orig,
518 const struct flowi *fl,
519 const struct sock *sk,
520 int flags)
521{
522 return dst_orig;
523}
524
525static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
526{
527 return NULL;
528}
529
530#else
531struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
532 const struct flowi *fl, const struct sock *sk,
533 int flags);
534
535struct dst_entry *xfrm_lookup_with_ifid(struct net *net,
536 struct dst_entry *dst_orig,
537 const struct flowi *fl,
538 const struct sock *sk, int flags,
539 u32 if_id);
540
541struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
542 const struct flowi *fl, const struct sock *sk,
543 int flags);
544
545/* skb attached with this dst needs transformation if dst->xfrm is valid */
546static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
547{
548 return dst->xfrm;
549}
550#endif
551
552static inline void skb_dst_update_pmtu(struct sk_buff *skb, u32 mtu)
553{
554 struct dst_entry *dst = skb_dst(skb);
555
556 if (dst && dst->ops->update_pmtu)
557 dst->ops->update_pmtu(dst, NULL, skb, mtu, true);
558}
559
560/* update dst pmtu but not do neighbor confirm */
561static inline void skb_dst_update_pmtu_no_confirm(struct sk_buff *skb, u32 mtu)
562{
563 struct dst_entry *dst = skb_dst(skb);
564
565 if (dst && dst->ops->update_pmtu)
566 dst->ops->update_pmtu(dst, NULL, skb, mtu, false);
567}
568
569static inline struct net_device *dst_dev(const struct dst_entry *dst)
570{
571 return READ_ONCE(dst->dev);
572}
573
574static inline struct net_device *dst_dev_rcu(const struct dst_entry *dst)
575{
576 return rcu_dereference(dst->dev_rcu);
577}
578
579static inline struct net *dst_dev_net_rcu(const struct dst_entry *dst)
580{
581 return dev_net_rcu(dev: dst_dev_rcu(dst));
582}
583
584static inline struct net_device *skb_dst_dev(const struct sk_buff *skb)
585{
586 return dst_dev(dst: skb_dst(skb));
587}
588
589static inline struct net_device *skb_dst_dev_rcu(const struct sk_buff *skb)
590{
591 return dst_dev_rcu(dst: skb_dst(skb));
592}
593
594static inline struct net *skb_dst_dev_net(const struct sk_buff *skb)
595{
596 return dev_net(dev: skb_dst_dev(skb));
597}
598
599static inline struct net *skb_dst_dev_net_rcu(const struct sk_buff *skb)
600{
601 return dev_net_rcu(dev: skb_dst_dev_rcu(skb));
602}
603
604struct dst_entry *dst_blackhole_check(struct dst_entry *dst, u32 cookie);
605void dst_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
606 struct sk_buff *skb, u32 mtu, bool confirm_neigh);
607void dst_blackhole_redirect(struct dst_entry *dst, struct sock *sk,
608 struct sk_buff *skb);
609u32 *dst_blackhole_cow_metrics(struct dst_entry *dst, unsigned long old);
610struct neighbour *dst_blackhole_neigh_lookup(const struct dst_entry *dst,
611 struct sk_buff *skb,
612 const void *daddr);
613unsigned int dst_blackhole_mtu(const struct dst_entry *dst);
614
615#endif /* _NET_DST_H */
616