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_HOST 0x0001 39 #define DST_NOXFRM 0x0002 40 #define DST_NOPOLICY 0x0004 41 #define DST_NOCOUNT 0x0008 42 #define DST_FAKE_RTABLE 0x0010 43 #define DST_XFRM_TUNNEL 0x0020 44 #define DST_XFRM_QUEUE 0x0040 45 #define DST_METADATA 0x0080 46 47 /* A non-zero value of dst->obsolete forces by-hand validation 48 * of the route entry. Positive values are set by the generic 49 * dst layer to indicate that the entry has been forcefully 50 * destroyed. 51 * 52 * Negative values are used by the implementation layer code to 53 * force invocation of the dst_ops->check() method. 54 */ 55 short obsolete; 56 #define DST_OBSOLETE_NONE 0 57 #define DST_OBSOLETE_DEAD 2 58 #define DST_OBSOLETE_FORCE_CHK -1 59 #define DST_OBSOLETE_KILL -2 60 unsigned short header_len; /* more space at head required */ 61 unsigned short trailer_len; /* space to reserve at tail */ 62 63 /* 64 * __refcnt wants to be on a different cache line from 65 * input/output/ops or performance tanks badly 66 */ 67 #ifdef CONFIG_64BIT 68 atomic_t __refcnt; /* 64-bit offset 64 */ 69 #endif 70 int __use; 71 unsigned long lastuse; 72 struct lwtunnel_state *lwtstate; 73 struct rcu_head rcu_head; 74 short error; 75 short __pad; 76 __u32 tclassid; 77 #ifndef CONFIG_64BIT 78 atomic_t __refcnt; /* 32-bit offset 64 */ 79 #endif 80 }; 81 82 struct dst_metrics { 83 u32 metrics[RTAX_MAX]; 84 refcount_t refcnt; 85 }; 86 extern const struct dst_metrics dst_default_metrics; 87 88 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old); 89 90 #define DST_METRICS_READ_ONLY 0x1UL 91 #define DST_METRICS_REFCOUNTED 0x2UL 92 #define DST_METRICS_FLAGS 0x3UL 93 #define __DST_METRICS_PTR(Y) \ 94 ((u32 *)((Y) & ~DST_METRICS_FLAGS)) 95 #define DST_METRICS_PTR(X) __DST_METRICS_PTR((X)->_metrics) 96 97 static inline bool dst_metrics_read_only(const struct dst_entry *dst) 98 { 99 return dst->_metrics & DST_METRICS_READ_ONLY; 100 } 101 102 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old); 103 104 static inline void dst_destroy_metrics_generic(struct dst_entry *dst) 105 { 106 unsigned long val = dst->_metrics; 107 if (!(val & DST_METRICS_READ_ONLY)) 108 __dst_destroy_metrics_generic(dst, val); 109 } 110 111 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst) 112 { 113 unsigned long p = dst->_metrics; 114 115 BUG_ON(!p); 116 117 if (p & DST_METRICS_READ_ONLY) 118 return dst->ops->cow_metrics(dst, p); 119 return __DST_METRICS_PTR(p); 120 } 121 122 /* This may only be invoked before the entry has reached global 123 * visibility. 124 */ 125 static inline void dst_init_metrics(struct dst_entry *dst, 126 const u32 *src_metrics, 127 bool read_only) 128 { 129 dst->_metrics = ((unsigned long) src_metrics) | 130 (read_only ? DST_METRICS_READ_ONLY : 0); 131 } 132 133 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src) 134 { 135 u32 *dst_metrics = dst_metrics_write_ptr(dest); 136 137 if (dst_metrics) { 138 u32 *src_metrics = DST_METRICS_PTR(src); 139 140 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32)); 141 } 142 } 143 144 static inline u32 *dst_metrics_ptr(struct dst_entry *dst) 145 { 146 return DST_METRICS_PTR(dst); 147 } 148 149 static inline u32 150 dst_metric_raw(const struct dst_entry *dst, const int metric) 151 { 152 u32 *p = DST_METRICS_PTR(dst); 153 154 return p[metric-1]; 155 } 156 157 static inline u32 158 dst_metric(const struct dst_entry *dst, const int metric) 159 { 160 WARN_ON_ONCE(metric == RTAX_HOPLIMIT || 161 metric == RTAX_ADVMSS || 162 metric == RTAX_MTU); 163 return dst_metric_raw(dst, metric); 164 } 165 166 static inline u32 167 dst_metric_advmss(const struct dst_entry *dst) 168 { 169 u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS); 170 171 if (!advmss) 172 advmss = dst->ops->default_advmss(dst); 173 174 return advmss; 175 } 176 177 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val) 178 { 179 u32 *p = dst_metrics_write_ptr(dst); 180 181 if (p) 182 p[metric-1] = val; 183 } 184 185 /* Kernel-internal feature bits that are unallocated in user space. */ 186 #define DST_FEATURE_ECN_CA (1 << 31) 187 188 #define DST_FEATURE_MASK (DST_FEATURE_ECN_CA) 189 #define DST_FEATURE_ECN_MASK (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN) 190 191 static inline u32 192 dst_feature(const struct dst_entry *dst, u32 feature) 193 { 194 return dst_metric(dst, RTAX_FEATURES) & feature; 195 } 196 197 static inline u32 dst_mtu(const struct dst_entry *dst) 198 { 199 return dst->ops->mtu(dst); 200 } 201 202 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */ 203 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric) 204 { 205 return msecs_to_jiffies(dst_metric(dst, metric)); 206 } 207 208 static inline u32 209 dst_allfrag(const struct dst_entry *dst) 210 { 211 int ret = dst_feature(dst, RTAX_FEATURE_ALLFRAG); 212 return ret; 213 } 214 215 static inline int 216 dst_metric_locked(const struct dst_entry *dst, int metric) 217 { 218 return dst_metric(dst, RTAX_LOCK) & (1<<metric); 219 } 220 221 static inline void dst_hold(struct dst_entry *dst) 222 { 223 /* 224 * If your kernel compilation stops here, please check 225 * the placement of __refcnt in struct dst_entry 226 */ 227 BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63); 228 WARN_ON(atomic_inc_not_zero(&dst->__refcnt) == 0); 229 } 230 231 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time) 232 { 233 if (unlikely(time != dst->lastuse)) { 234 dst->__use++; 235 dst->lastuse = time; 236 } 237 } 238 239 static inline void dst_hold_and_use(struct dst_entry *dst, unsigned long time) 240 { 241 dst_hold(dst); 242 dst_use_noref(dst, time); 243 } 244 245 static inline struct dst_entry *dst_clone(struct dst_entry *dst) 246 { 247 if (dst) 248 dst_hold(dst); 249 return dst; 250 } 251 252 void dst_release(struct dst_entry *dst); 253 254 void dst_release_immediate(struct dst_entry *dst); 255 256 static inline void refdst_drop(unsigned long refdst) 257 { 258 if (!(refdst & SKB_DST_NOREF)) 259 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK)); 260 } 261 262 /** 263 * skb_dst_drop - drops skb dst 264 * @skb: buffer 265 * 266 * Drops dst reference count if a reference was taken. 267 */ 268 static inline void skb_dst_drop(struct sk_buff *skb) 269 { 270 if (skb->_skb_refdst) { 271 refdst_drop(skb->_skb_refdst); 272 skb->_skb_refdst = 0UL; 273 } 274 } 275 276 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst) 277 { 278 nskb->_skb_refdst = refdst; 279 if (!(nskb->_skb_refdst & SKB_DST_NOREF)) 280 dst_clone(skb_dst(nskb)); 281 } 282 283 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb) 284 { 285 __skb_dst_copy(nskb, oskb->_skb_refdst); 286 } 287 288 /** 289 * dst_hold_safe - Take a reference on a dst if possible 290 * @dst: pointer to dst entry 291 * 292 * This helper returns false if it could not safely 293 * take a reference on a dst. 294 */ 295 static inline bool dst_hold_safe(struct dst_entry *dst) 296 { 297 return atomic_inc_not_zero(&dst->__refcnt); 298 } 299 300 /** 301 * skb_dst_force - makes sure skb dst is refcounted 302 * @skb: buffer 303 * 304 * If dst is not yet refcounted and not destroyed, grab a ref on it. 305 */ 306 static inline void 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 } 318 319 320 /** 321 * __skb_tunnel_rx - prepare skb for rx reinsert 322 * @skb: buffer 323 * @dev: tunnel device 324 * @net: netns for packet i/o 325 * 326 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 327 * so make some cleanups. (no accounting done) 328 */ 329 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev, 330 struct net *net) 331 { 332 skb->dev = dev; 333 334 /* 335 * Clear hash so that we can recalulate the hash for the 336 * encapsulated packet, unless we have already determine the hash 337 * over the L4 4-tuple. 338 */ 339 skb_clear_hash_if_not_l4(skb); 340 skb_set_queue_mapping(skb, 0); 341 skb_scrub_packet(skb, !net_eq(net, dev_net(dev))); 342 } 343 344 /** 345 * skb_tunnel_rx - prepare skb for rx reinsert 346 * @skb: buffer 347 * @dev: tunnel device 348 * @net: netns for packet i/o 349 * 350 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 351 * so make some cleanups, and perform accounting. 352 * Note: this accounting is not SMP safe. 353 */ 354 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev, 355 struct net *net) 356 { 357 /* TODO : stats should be SMP safe */ 358 dev->stats.rx_packets++; 359 dev->stats.rx_bytes += skb->len; 360 __skb_tunnel_rx(skb, dev, net); 361 } 362 363 static inline u32 dst_tclassid(const struct sk_buff *skb) 364 { 365 #ifdef CONFIG_IP_ROUTE_CLASSID 366 const struct dst_entry *dst; 367 368 dst = skb_dst(skb); 369 if (dst) 370 return dst->tclassid; 371 #endif 372 return 0; 373 } 374 375 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb); 376 static inline int dst_discard(struct sk_buff *skb) 377 { 378 return dst_discard_out(&init_net, skb->sk, skb); 379 } 380 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref, 381 int initial_obsolete, unsigned short flags); 382 void dst_init(struct dst_entry *dst, struct dst_ops *ops, 383 struct net_device *dev, int initial_ref, int initial_obsolete, 384 unsigned short flags); 385 struct dst_entry *dst_destroy(struct dst_entry *dst); 386 void dst_dev_put(struct dst_entry *dst); 387 388 static inline void dst_confirm(struct dst_entry *dst) 389 { 390 } 391 392 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr) 393 { 394 struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr); 395 return IS_ERR(n) ? NULL : n; 396 } 397 398 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst, 399 struct sk_buff *skb) 400 { 401 struct neighbour *n = dst->ops->neigh_lookup(dst, skb, NULL); 402 return IS_ERR(n) ? NULL : n; 403 } 404 405 static inline void dst_confirm_neigh(const struct dst_entry *dst, 406 const void *daddr) 407 { 408 if (dst->ops->confirm_neigh) 409 dst->ops->confirm_neigh(dst, daddr); 410 } 411 412 static inline void dst_link_failure(struct sk_buff *skb) 413 { 414 struct dst_entry *dst = skb_dst(skb); 415 if (dst && dst->ops && dst->ops->link_failure) 416 dst->ops->link_failure(skb); 417 } 418 419 static inline void dst_set_expires(struct dst_entry *dst, int timeout) 420 { 421 unsigned long expires = jiffies + timeout; 422 423 if (expires == 0) 424 expires = 1; 425 426 if (dst->expires == 0 || time_before(expires, dst->expires)) 427 dst->expires = expires; 428 } 429 430 /* Output packet to network from transport. */ 431 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb) 432 { 433 return skb_dst(skb)->output(net, sk, skb); 434 } 435 436 /* Input packet from network to transport. */ 437 static inline int dst_input(struct sk_buff *skb) 438 { 439 return skb_dst(skb)->input(skb); 440 } 441 442 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) 443 { 444 if (dst->obsolete) 445 dst = dst->ops->check(dst, cookie); 446 return dst; 447 } 448 449 /* Flags for xfrm_lookup flags argument. */ 450 enum { 451 XFRM_LOOKUP_ICMP = 1 << 0, 452 XFRM_LOOKUP_QUEUE = 1 << 1, 453 XFRM_LOOKUP_KEEP_DST_REF = 1 << 2, 454 }; 455 456 struct flowi; 457 #ifndef CONFIG_XFRM 458 static inline struct dst_entry *xfrm_lookup(struct net *net, 459 struct dst_entry *dst_orig, 460 const struct flowi *fl, 461 const struct sock *sk, 462 int flags) 463 { 464 return dst_orig; 465 } 466 467 static inline struct dst_entry * 468 xfrm_lookup_with_ifid(struct net *net, struct dst_entry *dst_orig, 469 const struct flowi *fl, const struct sock *sk, 470 int flags, u32 if_id) 471 { 472 return dst_orig; 473 } 474 475 static inline struct dst_entry *xfrm_lookup_route(struct net *net, 476 struct dst_entry *dst_orig, 477 const struct flowi *fl, 478 const struct sock *sk, 479 int flags) 480 { 481 return dst_orig; 482 } 483 484 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst) 485 { 486 return NULL; 487 } 488 489 #else 490 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig, 491 const struct flowi *fl, const struct sock *sk, 492 int flags); 493 494 struct dst_entry *xfrm_lookup_with_ifid(struct net *net, 495 struct dst_entry *dst_orig, 496 const struct flowi *fl, 497 const struct sock *sk, int flags, 498 u32 if_id); 499 500 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig, 501 const struct flowi *fl, const struct sock *sk, 502 int flags); 503 504 /* skb attached with this dst needs transformation if dst->xfrm is valid */ 505 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst) 506 { 507 return dst->xfrm; 508 } 509 #endif 510 511 static inline void skb_dst_update_pmtu(struct sk_buff *skb, u32 mtu) 512 { 513 struct dst_entry *dst = skb_dst(skb); 514 515 if (dst && dst->ops->update_pmtu) 516 dst->ops->update_pmtu(dst, NULL, skb, mtu); 517 } 518 519 static inline void skb_tunnel_check_pmtu(struct sk_buff *skb, 520 struct dst_entry *encap_dst, 521 int headroom) 522 { 523 u32 encap_mtu = dst_mtu(encap_dst); 524 525 if (skb->len > encap_mtu - headroom) 526 skb_dst_update_pmtu(skb, encap_mtu - headroom); 527 } 528 529 #endif /* _NET_DST_H */ 530