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 22 struct sk_buff; 23 24 struct 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 81 struct dst_metrics { 82 u32 metrics[RTAX_MAX]; 83 refcount_t refcnt; 84 } __aligned(4); /* Low pointer bits contain DST_METRICS_FLAGS */ 85 extern const struct dst_metrics dst_default_metrics; 86 87 u32 *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 96 static inline bool dst_metrics_read_only(const struct dst_entry *dst) 97 { 98 return dst->_metrics & DST_METRICS_READ_ONLY; 99 } 100 101 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old); 102 103 static 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 } 109 110 static 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 */ 124 static 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 } 131 132 static 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 } 142 143 static inline u32 *dst_metrics_ptr(struct dst_entry *dst) 144 { 145 return DST_METRICS_PTR(dst); 146 } 147 148 static inline u32 149 dst_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 } 155 156 static inline u32 157 dst_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 } 164 165 static inline u32 166 dst_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 } 175 176 static 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) 189 190 static inline u32 191 dst_feature(const struct dst_entry *dst, u32 feature) 192 { 193 return dst_metric(dst, RTAX_FEATURES) & feature; 194 } 195 196 static 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 */ 202 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric) 203 { 204 return msecs_to_jiffies(dst_metric(dst, metric)); 205 } 206 207 static inline u32 208 dst_allfrag(const struct dst_entry *dst) 209 { 210 int ret = dst_feature(dst, RTAX_FEATURE_ALLFRAG); 211 return ret; 212 } 213 214 static inline int 215 dst_metric_locked(const struct dst_entry *dst, int metric) 216 { 217 return dst_metric(dst, RTAX_LOCK) & (1<<metric); 218 } 219 220 static 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 } 229 230 static 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 } 237 238 static inline void dst_hold_and_use(struct dst_entry *dst, unsigned long time) 239 { 240 dst_hold(dst); 241 dst_use_noref(dst, time); 242 } 243 244 static inline struct dst_entry *dst_clone(struct dst_entry *dst) 245 { 246 if (dst) 247 dst_hold(dst); 248 return dst; 249 } 250 251 void dst_release(struct dst_entry *dst); 252 253 void dst_release_immediate(struct dst_entry *dst); 254 255 static inline void refdst_drop(unsigned long refdst) 256 { 257 if (!(refdst & SKB_DST_NOREF)) 258 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK)); 259 } 260 261 /** 262 * skb_dst_drop - drops skb dst 263 * @skb: buffer 264 * 265 * Drops dst reference count if a reference was taken. 266 */ 267 static inline void skb_dst_drop(struct sk_buff *skb) 268 { 269 if (skb->_skb_refdst) { 270 refdst_drop(skb->_skb_refdst); 271 skb->_skb_refdst = 0UL; 272 } 273 } 274 275 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst) 276 { 277 nskb->_skb_refdst = refdst; 278 if (!(nskb->_skb_refdst & SKB_DST_NOREF)) 279 dst_clone(skb_dst(nskb)); 280 } 281 282 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb) 283 { 284 __skb_dst_copy(nskb, oskb->_skb_refdst); 285 } 286 287 /** 288 * dst_hold_safe - Take a reference on a dst if possible 289 * @dst: pointer to dst entry 290 * 291 * This helper returns false if it could not safely 292 * take a reference on a dst. 293 */ 294 static inline bool dst_hold_safe(struct dst_entry *dst) 295 { 296 return atomic_inc_not_zero(&dst->__refcnt); 297 } 298 299 /** 300 * skb_dst_force - makes sure skb dst is refcounted 301 * @skb: buffer 302 * 303 * If dst is not yet refcounted and not destroyed, grab a ref on it. 304 * Returns true if dst is refcounted. 305 */ 306 static inline bool skb_dst_force(struct sk_buff *skb) 307 { 308 if (skb_dst_is_noref(skb)) { 309 struct dst_entry *dst = skb_dst(skb); 310 311 WARN_ON(!rcu_read_lock_held()); 312 if (!dst_hold_safe(dst)) 313 dst = NULL; 314 315 skb->_skb_refdst = (unsigned long)dst; 316 } 317 318 return skb->_skb_refdst != 0UL; 319 } 320 321 322 /** 323 * __skb_tunnel_rx - prepare skb for rx reinsert 324 * @skb: buffer 325 * @dev: tunnel device 326 * @net: netns for packet i/o 327 * 328 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 329 * so make some cleanups. (no accounting done) 330 */ 331 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev, 332 struct net *net) 333 { 334 skb->dev = dev; 335 336 /* 337 * Clear hash so that we can recalulate the hash for the 338 * encapsulated packet, unless we have already determine the hash 339 * over the L4 4-tuple. 340 */ 341 skb_clear_hash_if_not_l4(skb); 342 skb_set_queue_mapping(skb, 0); 343 skb_scrub_packet(skb, !net_eq(net, dev_net(dev))); 344 } 345 346 /** 347 * skb_tunnel_rx - prepare skb for rx reinsert 348 * @skb: buffer 349 * @dev: tunnel device 350 * @net: netns for packet i/o 351 * 352 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 353 * so make some cleanups, and perform accounting. 354 * Note: this accounting is not SMP safe. 355 */ 356 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev, 357 struct net *net) 358 { 359 /* TODO : stats should be SMP safe */ 360 dev->stats.rx_packets++; 361 dev->stats.rx_bytes += skb->len; 362 __skb_tunnel_rx(skb, dev, net); 363 } 364 365 static inline u32 dst_tclassid(const struct sk_buff *skb) 366 { 367 #ifdef CONFIG_IP_ROUTE_CLASSID 368 const struct dst_entry *dst; 369 370 dst = skb_dst(skb); 371 if (dst) 372 return dst->tclassid; 373 #endif 374 return 0; 375 } 376 377 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb); 378 static inline int dst_discard(struct sk_buff *skb) 379 { 380 return dst_discard_out(&init_net, skb->sk, skb); 381 } 382 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref, 383 int initial_obsolete, unsigned short flags); 384 void dst_init(struct dst_entry *dst, struct dst_ops *ops, 385 struct net_device *dev, int initial_ref, int initial_obsolete, 386 unsigned short flags); 387 struct dst_entry *dst_destroy(struct dst_entry *dst); 388 void dst_dev_put(struct dst_entry *dst); 389 390 static inline void dst_confirm(struct dst_entry *dst) 391 { 392 } 393 394 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr) 395 { 396 struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr); 397 return IS_ERR(n) ? NULL : n; 398 } 399 400 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst, 401 struct sk_buff *skb) 402 { 403 struct neighbour *n = dst->ops->neigh_lookup(dst, skb, NULL); 404 return IS_ERR(n) ? NULL : n; 405 } 406 407 static inline void dst_confirm_neigh(const struct dst_entry *dst, 408 const void *daddr) 409 { 410 if (dst->ops->confirm_neigh) 411 dst->ops->confirm_neigh(dst, daddr); 412 } 413 414 static inline void dst_link_failure(struct sk_buff *skb) 415 { 416 struct dst_entry *dst = skb_dst(skb); 417 if (dst && dst->ops && dst->ops->link_failure) 418 dst->ops->link_failure(skb); 419 } 420 421 static inline void dst_set_expires(struct dst_entry *dst, int timeout) 422 { 423 unsigned long expires = jiffies + timeout; 424 425 if (expires == 0) 426 expires = 1; 427 428 if (dst->expires == 0 || time_before(expires, dst->expires)) 429 dst->expires = expires; 430 } 431 432 /* Output packet to network from transport. */ 433 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb) 434 { 435 return skb_dst(skb)->output(net, sk, skb); 436 } 437 438 /* Input packet from network to transport. */ 439 static inline int dst_input(struct sk_buff *skb) 440 { 441 return skb_dst(skb)->input(skb); 442 } 443 444 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) 445 { 446 if (dst->obsolete) 447 dst = dst->ops->check(dst, cookie); 448 return dst; 449 } 450 451 /* Flags for xfrm_lookup flags argument. */ 452 enum { 453 XFRM_LOOKUP_ICMP = 1 << 0, 454 XFRM_LOOKUP_QUEUE = 1 << 1, 455 XFRM_LOOKUP_KEEP_DST_REF = 1 << 2, 456 }; 457 458 struct flowi; 459 #ifndef CONFIG_XFRM 460 static inline struct dst_entry *xfrm_lookup(struct net *net, 461 struct dst_entry *dst_orig, 462 const struct flowi *fl, 463 const struct sock *sk, 464 int flags) 465 { 466 return dst_orig; 467 } 468 469 static inline struct dst_entry * 470 xfrm_lookup_with_ifid(struct net *net, struct dst_entry *dst_orig, 471 const struct flowi *fl, const struct sock *sk, 472 int flags, u32 if_id) 473 { 474 return dst_orig; 475 } 476 477 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, 481 int flags) 482 { 483 return dst_orig; 484 } 485 486 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst) 487 { 488 return NULL; 489 } 490 491 #else 492 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig, 493 const struct flowi *fl, const struct sock *sk, 494 int flags); 495 496 struct dst_entry *xfrm_lookup_with_ifid(struct net *net, 497 struct dst_entry *dst_orig, 498 const struct flowi *fl, 499 const struct sock *sk, int flags, 500 u32 if_id); 501 502 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig, 503 const struct flowi *fl, const struct sock *sk, 504 int flags); 505 506 /* skb attached with this dst needs transformation if dst->xfrm is valid */ 507 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst) 508 { 509 return dst->xfrm; 510 } 511 #endif 512 513 static inline void skb_dst_update_pmtu(struct sk_buff *skb, u32 mtu) 514 { 515 struct dst_entry *dst = skb_dst(skb); 516 517 if (dst && dst->ops->update_pmtu) 518 dst->ops->update_pmtu(dst, NULL, skb, mtu, true); 519 } 520 521 /* update dst pmtu but not do neighbor confirm */ 522 static inline void skb_dst_update_pmtu_no_confirm(struct sk_buff *skb, u32 mtu) 523 { 524 struct dst_entry *dst = skb_dst(skb); 525 526 if (dst && dst->ops->update_pmtu) 527 dst->ops->update_pmtu(dst, NULL, skb, mtu, false); 528 } 529 530 static inline void skb_tunnel_check_pmtu(struct sk_buff *skb, 531 struct dst_entry *encap_dst, 532 int headroom) 533 { 534 u32 encap_mtu = dst_mtu(encap_dst); 535 536 if (skb->len > encap_mtu - headroom) 537 skb_dst_update_pmtu_no_confirm(skb, encap_mtu - headroom); 538 } 539 540 #endif /* _NET_DST_H */ 541