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 22struct sk_buff; 23 24struct dst_entry { 25 struct net_device *dev; 26 struct dst_ops *ops; 27 unsigned long _metrics; 28 unsigned long expires; 29#ifdef CONFIG_XFRM 30 struct xfrm_state *xfrm; 31#else 32 void *__pad1; 33#endif 34 int (*input)(struct sk_buff *); 35 int (*output)(struct net *net, struct sock *sk, struct sk_buff *skb); 36 37 unsigned short flags; 38#define DST_NOXFRM 0x0002 39#define DST_NOPOLICY 0x0004 40#define DST_NOCOUNT 0x0008 41#define DST_FAKE_RTABLE 0x0010 42#define DST_XFRM_TUNNEL 0x0020 43#define DST_XFRM_QUEUE 0x0040 44#define DST_METADATA 0x0080 45 46 /* A non-zero value of dst->obsolete forces by-hand validation 47 * of the route entry. Positive values are set by the generic 48 * dst layer to indicate that the entry has been forcefully 49 * destroyed. 50 * 51 * Negative values are used by the implementation layer code to 52 * force invocation of the dst_ops->check() method. 53 */ 54 short obsolete; 55#define DST_OBSOLETE_NONE 0 56#define DST_OBSOLETE_DEAD 2 57#define DST_OBSOLETE_FORCE_CHK -1 58#define DST_OBSOLETE_KILL -2 59 unsigned short header_len; /* more space at head required */ 60 unsigned short trailer_len; /* space to reserve at tail */ 61 62 /* 63 * __refcnt wants to be on a different cache line from 64 * input/output/ops or performance tanks badly 65 */ 66#ifdef CONFIG_64BIT 67 atomic_t __refcnt; /* 64-bit offset 64 */ 68#endif 69 int __use; 70 unsigned long lastuse; 71 struct lwtunnel_state *lwtstate; 72 struct rcu_head rcu_head; 73 short error; 74 short __pad; 75 __u32 tclassid; 76#ifndef CONFIG_64BIT 77 atomic_t __refcnt; /* 32-bit offset 64 */ 78#endif 79}; 80 81struct dst_metrics { 82 u32 metrics[RTAX_MAX]; 83 refcount_t refcnt; 84} __aligned(4); /* Low pointer bits contain DST_METRICS_FLAGS */ 85extern const struct dst_metrics dst_default_metrics; 86 87u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old); 88 89#define DST_METRICS_READ_ONLY 0x1UL 90#define DST_METRICS_REFCOUNTED 0x2UL 91#define DST_METRICS_FLAGS 0x3UL 92#define __DST_METRICS_PTR(Y) \ 93 ((u32 *)((Y) & ~DST_METRICS_FLAGS)) 94#define DST_METRICS_PTR(X) __DST_METRICS_PTR((X)->_metrics) 95 96static inline bool dst_metrics_read_only(const struct dst_entry *dst) 97{ 98 return dst->_metrics & DST_METRICS_READ_ONLY; 99} 100 101void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old); 102 103static inline void dst_destroy_metrics_generic(struct dst_entry *dst) 104{ 105 unsigned long val = dst->_metrics; 106 if (!(val & DST_METRICS_READ_ONLY)) 107 __dst_destroy_metrics_generic(dst, val); 108} 109 110static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst) 111{ 112 unsigned long p = dst->_metrics; 113 114 BUG_ON(!p); 115 116 if (p & DST_METRICS_READ_ONLY) 117 return dst->ops->cow_metrics(dst, p); 118 return __DST_METRICS_PTR(p); 119} 120 121/* This may only be invoked before the entry has reached global 122 * visibility. 123 */ 124static inline void dst_init_metrics(struct dst_entry *dst, 125 const u32 *src_metrics, 126 bool read_only) 127{ 128 dst->_metrics = ((unsigned long) src_metrics) | 129 (read_only ? DST_METRICS_READ_ONLY : 0); 130} 131 132static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src) 133{ 134 u32 *dst_metrics = dst_metrics_write_ptr(dest); 135 136 if (dst_metrics) { 137 u32 *src_metrics = DST_METRICS_PTR(src); 138 139 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32)); 140 } 141} 142 143static inline u32 *dst_metrics_ptr(struct dst_entry *dst) 144{ 145 return DST_METRICS_PTR(dst); 146} 147 148static inline u32 149dst_metric_raw(const struct dst_entry *dst, const int metric) 150{ 151 u32 *p = DST_METRICS_PTR(dst); 152 153 return p[metric-1]; 154} 155 156static inline u32 157dst_metric(const struct dst_entry *dst, const int metric) 158{ 159 WARN_ON_ONCE(metric == RTAX_HOPLIMIT || 160 metric == RTAX_ADVMSS || 161 metric == RTAX_MTU); 162 return dst_metric_raw(dst, metric); 163} 164 165static inline u32 166dst_metric_advmss(const struct dst_entry *dst) 167{ 168 u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS); 169 170 if (!advmss) 171 advmss = dst->ops->default_advmss(dst); 172 173 return advmss; 174} 175 176static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val) 177{ 178 u32 *p = dst_metrics_write_ptr(dst); 179 180 if (p) 181 p[metric-1] = val; 182} 183 184/* Kernel-internal feature bits that are unallocated in user space. */ 185#define DST_FEATURE_ECN_CA (1U << 31) 186 187#define DST_FEATURE_MASK (DST_FEATURE_ECN_CA) 188#define DST_FEATURE_ECN_MASK (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN) 189 190static inline u32 191dst_feature(const struct dst_entry *dst, u32 feature) 192{ 193 return dst_metric(dst, RTAX_FEATURES) & feature; 194} 195 196static inline u32 dst_mtu(const struct dst_entry *dst) 197{ 198 return dst->ops->mtu(dst); 199} 200 201/* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */ 202static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric) 203{ 204 return msecs_to_jiffies(dst_metric(dst, metric)); 205} 206 207static inline u32 208dst_allfrag(const struct dst_entry *dst) 209{ 210 int ret = dst_feature(dst, RTAX_FEATURE_ALLFRAG); 211 return ret; 212} 213 214static inline int 215dst_metric_locked(const struct dst_entry *dst, int metric) 216{ 217 return dst_metric(dst, RTAX_LOCK) & (1 << metric); 218} 219 220static inline void dst_hold(struct dst_entry *dst) 221{ 222 /* 223 * If your kernel compilation stops here, please check 224 * the placement of __refcnt in struct dst_entry 225 */ 226 BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63); 227 WARN_ON(atomic_inc_not_zero(&dst->__refcnt) == 0); 228} 229 230static inline void dst_use_noref(struct dst_entry *dst, unsigned long time) 231{ 232 if (unlikely(time != dst->lastuse)) { 233 dst->__use++; 234 dst->lastuse = time; 235 } 236} 237 238static inline struct dst_entry *dst_clone(struct dst_entry *dst) 239{ 240 if (dst) 241 dst_hold(dst); 242 return dst; 243} 244 245void dst_release(struct dst_entry *dst); 246 247void dst_release_immediate(struct dst_entry *dst); 248 249static inline void refdst_drop(unsigned long refdst) 250{ 251 if (!(refdst & SKB_DST_NOREF)) 252 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK)); 253} 254 255/** 256 * skb_dst_drop - drops skb dst 257 * @skb: buffer 258 * 259 * Drops dst reference count if a reference was taken. 260 */ 261static inline void skb_dst_drop(struct sk_buff *skb) 262{ 263 if (skb->_skb_refdst) { 264 refdst_drop(skb->_skb_refdst); 265 skb->_skb_refdst = 0UL; 266 } 267} 268 269static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst) 270{ 271 nskb->_skb_refdst = refdst; 272 if (!(nskb->_skb_refdst & SKB_DST_NOREF)) 273 dst_clone(skb_dst(nskb)); 274} 275 276static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb) 277{ 278 __skb_dst_copy(nskb, oskb->_skb_refdst); 279} 280 281/** 282 * dst_hold_safe - Take a reference on a dst if possible 283 * @dst: pointer to dst entry 284 * 285 * This helper returns false if it could not safely 286 * take a reference on a dst. 287 */ 288static inline bool dst_hold_safe(struct dst_entry *dst) 289{ 290 return atomic_inc_not_zero(&dst->__refcnt); 291} 292 293/** 294 * skb_dst_force - makes sure skb dst is refcounted 295 * @skb: buffer 296 * 297 * If dst is not yet refcounted and not destroyed, grab a ref on it. 298 * Returns true if dst is refcounted. 299 */ 300static inline bool skb_dst_force(struct sk_buff *skb) 301{ 302 if (skb_dst_is_noref(skb)) { 303 struct dst_entry *dst = skb_dst(skb); 304 305 WARN_ON(!rcu_read_lock_held()); 306 if (!dst_hold_safe(dst)) 307 dst = NULL; 308 309 skb->_skb_refdst = (unsigned long)dst; 310 } 311 312 return skb->_skb_refdst != 0UL; 313} 314 315 316/** 317 * __skb_tunnel_rx - prepare skb for rx reinsert 318 * @skb: buffer 319 * @dev: tunnel device 320 * @net: netns for packet i/o 321 * 322 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 323 * so make some cleanups. (no accounting done) 324 */ 325static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev, 326 struct net *net) 327{ 328 skb->dev = dev; 329 330 /* 331 * Clear hash so that we can recalulate the hash for the 332 * encapsulated packet, unless we have already determine the hash 333 * over the L4 4-tuple. 334 */ 335 skb_clear_hash_if_not_l4(skb); 336 skb_set_queue_mapping(skb, 0); 337 skb_scrub_packet(skb, !net_eq(net, dev_net(dev))); 338} 339 340/** 341 * skb_tunnel_rx - prepare skb for rx reinsert 342 * @skb: buffer 343 * @dev: tunnel device 344 * @net: netns for packet i/o 345 * 346 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 347 * so make some cleanups, and perform accounting. 348 * Note: this accounting is not SMP safe. 349 */ 350static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev, 351 struct net *net) 352{ 353 DEV_STATS_INC(dev, rx_packets); 354 DEV_STATS_ADD(dev, rx_bytes, skb->len); 355 __skb_tunnel_rx(skb, dev, net); 356} 357 358static inline u32 dst_tclassid(const struct sk_buff *skb) 359{ 360#ifdef CONFIG_IP_ROUTE_CLASSID 361 const struct dst_entry *dst; 362 363 dst = skb_dst(skb); 364 if (dst) 365 return dst->tclassid; 366#endif 367 return 0; 368} 369 370int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb); 371static inline int dst_discard(struct sk_buff *skb) 372{ 373 return dst_discard_out(&init_net, skb->sk, skb); 374} 375void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref, 376 int initial_obsolete, unsigned short flags); 377void dst_init(struct dst_entry *dst, struct dst_ops *ops, 378 struct net_device *dev, int initial_ref, int initial_obsolete, 379 unsigned short flags); 380struct dst_entry *dst_destroy(struct dst_entry *dst); 381void dst_dev_put(struct dst_entry *dst); 382 383static inline void dst_confirm(struct dst_entry *dst) 384{ 385} 386 387static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr) 388{ 389 struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr); 390 return IS_ERR(n) ? NULL : n; 391} 392 393static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst, 394 struct sk_buff *skb) 395{ 396 struct neighbour *n = NULL; 397 398 /* The packets from tunnel devices (eg bareudp) may have only 399 * metadata in the dst pointer of skb. Hence a pointer check of 400 * neigh_lookup is needed. 401 */ 402 if (dst->ops->neigh_lookup) 403 n = dst->ops->neigh_lookup(dst, skb, NULL); 404 405 return IS_ERR(n) ? NULL : n; 406} 407 408static inline void dst_confirm_neigh(const struct dst_entry *dst, 409 const void *daddr) 410{ 411 if (dst->ops->confirm_neigh) 412 dst->ops->confirm_neigh(dst, daddr); 413} 414 415static inline void dst_link_failure(struct sk_buff *skb) 416{ 417 struct dst_entry *dst = skb_dst(skb); 418 if (dst && dst->ops && dst->ops->link_failure) 419 dst->ops->link_failure(skb); 420} 421 422static inline void dst_set_expires(struct dst_entry *dst, int timeout) 423{ 424 unsigned long expires = jiffies + timeout; 425 426 if (expires == 0) 427 expires = 1; 428 429 if (dst->expires == 0 || time_before(expires, dst->expires)) 430 dst->expires = expires; 431} 432 433/* Output packet to network from transport. */ 434static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb) 435{ 436 return skb_dst(skb)->output(net, sk, skb); 437} 438 439/* Input packet from network to transport. */ 440static inline int dst_input(struct sk_buff *skb) 441{ 442 return skb_dst(skb)->input(skb); 443} 444 445static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) 446{ 447 if (dst->obsolete) 448 dst = dst->ops->check(dst, cookie); 449 return dst; 450} 451 452/* Flags for xfrm_lookup flags argument. */ 453enum { 454 XFRM_LOOKUP_ICMP = 1 << 0, 455 XFRM_LOOKUP_QUEUE = 1 << 1, 456 XFRM_LOOKUP_KEEP_DST_REF = 1 << 2, 457}; 458 459struct flowi; 460#ifndef CONFIG_XFRM 461static inline struct dst_entry *xfrm_lookup(struct net *net, 462 struct dst_entry *dst_orig, 463 const struct flowi *fl, 464 const struct sock *sk, 465 int flags) 466{ 467 return dst_orig; 468} 469 470static inline struct dst_entry * 471xfrm_lookup_with_ifid(struct net *net, struct dst_entry *dst_orig, 472 const struct flowi *fl, const struct sock *sk, 473 int flags, u32 if_id) 474{ 475 return dst_orig; 476} 477 478static inline struct dst_entry *xfrm_lookup_route(struct net *net, 479 struct dst_entry *dst_orig, 480 const struct flowi *fl, 481 const struct sock *sk, 482 int flags) 483{ 484 return dst_orig; 485} 486 487static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst) 488{ 489 return NULL; 490} 491 492#else 493struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig, 494 const struct flowi *fl, const struct sock *sk, 495 int flags); 496 497struct dst_entry *xfrm_lookup_with_ifid(struct net *net, 498 struct dst_entry *dst_orig, 499 const struct flowi *fl, 500 const struct sock *sk, int flags, 501 u32 if_id); 502 503struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig, 504 const struct flowi *fl, const struct sock *sk, 505 int flags); 506 507/* skb attached with this dst needs transformation if dst->xfrm is valid */ 508static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst) 509{ 510 return dst->xfrm; 511} 512#endif 513 514static inline void skb_dst_update_pmtu(struct sk_buff *skb, u32 mtu) 515{ 516 struct dst_entry *dst = skb_dst(skb); 517 518 if (dst && dst->ops->update_pmtu) 519 dst->ops->update_pmtu(dst, NULL, skb, mtu, true); 520} 521 522/* update dst pmtu but not do neighbor confirm */ 523static inline void skb_dst_update_pmtu_no_confirm(struct sk_buff *skb, u32 mtu) 524{ 525 struct dst_entry *dst = skb_dst(skb); 526 527 if (dst && dst->ops->update_pmtu) 528 dst->ops->update_pmtu(dst, NULL, skb, mtu, false); 529} 530 531struct dst_entry *dst_blackhole_check(struct dst_entry *dst, u32 cookie); 532void dst_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk, 533 struct sk_buff *skb, u32 mtu, bool confirm_neigh); 534void dst_blackhole_redirect(struct dst_entry *dst, struct sock *sk, 535 struct sk_buff *skb); 536u32 *dst_blackhole_cow_metrics(struct dst_entry *dst, unsigned long old); 537struct neighbour *dst_blackhole_neigh_lookup(const struct dst_entry *dst, 538 struct sk_buff *skb, 539 const void *daddr); 540unsigned int dst_blackhole_mtu(const struct dst_entry *dst); 541 542#endif /* _NET_DST_H */ 543