1 /* SPDX-License-Identifier: GPL-2.0 */
3 * net/dst.h Protocol independent destination cache definitions.
5 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
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>
22 #define DST_GC_MIN (HZ/10)
23 #define DST_GC_INC (HZ/2)
24 #define DST_GC_MAX (120*HZ)
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.
36 struct net_device *dev;
38 unsigned long _metrics;
39 unsigned long expires;
41 struct xfrm_state *xfrm;
45 int (*input)(struct sk_buff *);
46 int (*output)(struct net *net, struct sock *sk, struct sk_buff *skb);
49 #define DST_HOST 0x0001
50 #define DST_NOXFRM 0x0002
51 #define DST_NOPOLICY 0x0004
52 #define DST_NOCOUNT 0x0008
53 #define DST_FAKE_RTABLE 0x0010
54 #define DST_XFRM_TUNNEL 0x0020
55 #define DST_XFRM_QUEUE 0x0040
56 #define DST_METADATA 0x0080
58 /* A non-zero value of dst->obsolete forces by-hand validation
59 * of the route entry. Positive values are set by the generic
60 * dst layer to indicate that the entry has been forcefully
63 * Negative values are used by the implementation layer code to
64 * force invocation of the dst_ops->check() method.
67 #define DST_OBSOLETE_NONE 0
68 #define DST_OBSOLETE_DEAD 2
69 #define DST_OBSOLETE_FORCE_CHK -1
70 #define DST_OBSOLETE_KILL -2
71 unsigned short header_len; /* more space at head required */
72 unsigned short trailer_len; /* space to reserve at tail */
75 * __refcnt wants to be on a different cache line from
76 * input/output/ops or performance tanks badly
79 atomic_t __refcnt; /* 64-bit offset 64 */
82 unsigned long lastuse;
83 struct lwtunnel_state *lwtstate;
84 struct rcu_head rcu_head;
89 atomic_t __refcnt; /* 32-bit offset 64 */
94 u32 metrics[RTAX_MAX];
97 extern const struct dst_metrics dst_default_metrics;
99 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
101 #define DST_METRICS_READ_ONLY 0x1UL
102 #define DST_METRICS_REFCOUNTED 0x2UL
103 #define DST_METRICS_FLAGS 0x3UL
104 #define __DST_METRICS_PTR(Y) \
105 ((u32 *)((Y) & ~DST_METRICS_FLAGS))
106 #define DST_METRICS_PTR(X) __DST_METRICS_PTR((X)->_metrics)
108 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
110 return dst->_metrics & DST_METRICS_READ_ONLY;
113 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
115 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
117 unsigned long val = dst->_metrics;
118 if (!(val & DST_METRICS_READ_ONLY))
119 __dst_destroy_metrics_generic(dst, val);
122 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
124 unsigned long p = dst->_metrics;
128 if (p & DST_METRICS_READ_ONLY)
129 return dst->ops->cow_metrics(dst, p);
130 return __DST_METRICS_PTR(p);
133 /* This may only be invoked before the entry has reached global
136 static inline void dst_init_metrics(struct dst_entry *dst,
137 const u32 *src_metrics,
140 dst->_metrics = ((unsigned long) src_metrics) |
141 (read_only ? DST_METRICS_READ_ONLY : 0);
144 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
146 u32 *dst_metrics = dst_metrics_write_ptr(dest);
149 u32 *src_metrics = DST_METRICS_PTR(src);
151 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
155 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
157 return DST_METRICS_PTR(dst);
161 dst_metric_raw(const struct dst_entry *dst, const int metric)
163 u32 *p = DST_METRICS_PTR(dst);
169 dst_metric(const struct dst_entry *dst, const int metric)
171 WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
172 metric == RTAX_ADVMSS ||
174 return dst_metric_raw(dst, metric);
178 dst_metric_advmss(const struct dst_entry *dst)
180 u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
183 advmss = dst->ops->default_advmss(dst);
188 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
190 u32 *p = dst_metrics_write_ptr(dst);
196 /* Kernel-internal feature bits that are unallocated in user space. */
197 #define DST_FEATURE_ECN_CA (1 << 31)
199 #define DST_FEATURE_MASK (DST_FEATURE_ECN_CA)
200 #define DST_FEATURE_ECN_MASK (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN)
203 dst_feature(const struct dst_entry *dst, u32 feature)
205 return dst_metric(dst, RTAX_FEATURES) & feature;
208 static inline u32 dst_mtu(const struct dst_entry *dst)
210 return dst->ops->mtu(dst);
213 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
214 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
216 return msecs_to_jiffies(dst_metric(dst, metric));
220 dst_allfrag(const struct dst_entry *dst)
222 int ret = dst_feature(dst, RTAX_FEATURE_ALLFRAG);
227 dst_metric_locked(const struct dst_entry *dst, int metric)
229 return dst_metric(dst, RTAX_LOCK) & (1<<metric);
232 static inline void dst_hold(struct dst_entry *dst)
235 * If your kernel compilation stops here, please check
236 * the placement of __refcnt in struct dst_entry
238 BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
239 WARN_ON(atomic_inc_not_zero(&dst->__refcnt) == 0);
242 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
244 if (unlikely(time != dst->lastuse)) {
250 static inline void dst_hold_and_use(struct dst_entry *dst, unsigned long time)
253 dst_use_noref(dst, time);
256 static inline struct dst_entry *dst_clone(struct dst_entry *dst)
263 void dst_release(struct dst_entry *dst);
265 void dst_release_immediate(struct dst_entry *dst);
267 static inline void refdst_drop(unsigned long refdst)
269 if (!(refdst & SKB_DST_NOREF))
270 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
274 * skb_dst_drop - drops skb dst
277 * Drops dst reference count if a reference was taken.
279 static inline void skb_dst_drop(struct sk_buff *skb)
281 if (skb->_skb_refdst) {
282 refdst_drop(skb->_skb_refdst);
283 skb->_skb_refdst = 0UL;
287 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst)
289 nskb->_skb_refdst = refdst;
290 if (!(nskb->_skb_refdst & SKB_DST_NOREF))
291 dst_clone(skb_dst(nskb));
294 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
296 __skb_dst_copy(nskb, oskb->_skb_refdst);
300 * dst_hold_safe - Take a reference on a dst if possible
301 * @dst: pointer to dst entry
303 * This helper returns false if it could not safely
304 * take a reference on a dst.
306 static inline bool dst_hold_safe(struct dst_entry *dst)
308 return atomic_inc_not_zero(&dst->__refcnt);
312 * skb_dst_force - makes sure skb dst is refcounted
315 * If dst is not yet refcounted and not destroyed, grab a ref on it.
317 static inline void skb_dst_force(struct sk_buff *skb)
319 if (skb_dst_is_noref(skb)) {
320 struct dst_entry *dst = skb_dst(skb);
322 WARN_ON(!rcu_read_lock_held());
323 if (!dst_hold_safe(dst))
326 skb->_skb_refdst = (unsigned long)dst;
332 * __skb_tunnel_rx - prepare skb for rx reinsert
334 * @dev: tunnel device
335 * @net: netns for packet i/o
337 * After decapsulation, packet is going to re-enter (netif_rx()) our stack,
338 * so make some cleanups. (no accounting done)
340 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
346 * Clear hash so that we can recalulate the hash for the
347 * encapsulated packet, unless we have already determine the hash
348 * over the L4 4-tuple.
350 skb_clear_hash_if_not_l4(skb);
351 skb_set_queue_mapping(skb, 0);
352 skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
356 * skb_tunnel_rx - prepare skb for rx reinsert
358 * @dev: tunnel device
360 * After decapsulation, packet is going to re-enter (netif_rx()) our stack,
361 * so make some cleanups, and perform accounting.
362 * Note: this accounting is not SMP safe.
364 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
367 /* TODO : stats should be SMP safe */
368 dev->stats.rx_packets++;
369 dev->stats.rx_bytes += skb->len;
370 __skb_tunnel_rx(skb, dev, net);
373 static inline u32 dst_tclassid(const struct sk_buff *skb)
375 #ifdef CONFIG_IP_ROUTE_CLASSID
376 const struct dst_entry *dst;
380 return dst->tclassid;
385 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
386 static inline int dst_discard(struct sk_buff *skb)
388 return dst_discard_out(&init_net, skb->sk, skb);
390 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref,
391 int initial_obsolete, unsigned short flags);
392 void dst_init(struct dst_entry *dst, struct dst_ops *ops,
393 struct net_device *dev, int initial_ref, int initial_obsolete,
394 unsigned short flags);
395 struct dst_entry *dst_destroy(struct dst_entry *dst);
396 void dst_dev_put(struct dst_entry *dst);
398 static inline void dst_confirm(struct dst_entry *dst)
402 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
404 struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
405 return IS_ERR(n) ? NULL : n;
408 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
411 struct neighbour *n = dst->ops->neigh_lookup(dst, skb, NULL);
412 return IS_ERR(n) ? NULL : n;
415 static inline void dst_confirm_neigh(const struct dst_entry *dst,
418 if (dst->ops->confirm_neigh)
419 dst->ops->confirm_neigh(dst, daddr);
422 static inline void dst_link_failure(struct sk_buff *skb)
424 struct dst_entry *dst = skb_dst(skb);
425 if (dst && dst->ops && dst->ops->link_failure)
426 dst->ops->link_failure(skb);
429 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
431 unsigned long expires = jiffies + timeout;
436 if (dst->expires == 0 || time_before(expires, dst->expires))
437 dst->expires = expires;
440 /* Output packet to network from transport. */
441 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb)
443 return skb_dst(skb)->output(net, sk, skb);
446 /* Input packet from network to transport. */
447 static inline int dst_input(struct sk_buff *skb)
449 return skb_dst(skb)->input(skb);
452 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
455 dst = dst->ops->check(dst, cookie);
459 /* Flags for xfrm_lookup flags argument. */
461 XFRM_LOOKUP_ICMP = 1 << 0,
462 XFRM_LOOKUP_QUEUE = 1 << 1,
463 XFRM_LOOKUP_KEEP_DST_REF = 1 << 2,
468 static inline struct dst_entry *xfrm_lookup(struct net *net,
469 struct dst_entry *dst_orig,
470 const struct flowi *fl,
471 const struct sock *sk,
477 static inline struct dst_entry *xfrm_lookup_route(struct net *net,
478 struct dst_entry *dst_orig,
479 const struct flowi *fl,
480 const struct sock *sk,
486 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
492 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
493 const struct flowi *fl, const struct sock *sk,
496 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
497 const struct flowi *fl, const struct sock *sk,
500 /* skb attached with this dst needs transformation if dst->xfrm is valid */
501 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
507 static inline void skb_dst_update_pmtu(struct sk_buff *skb, u32 mtu)
509 struct dst_entry *dst = skb_dst(skb);
511 if (dst && dst->ops->update_pmtu)
512 dst->ops->update_pmtu(dst, NULL, skb, mtu);
515 #endif /* _NET_DST_H */