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 #define DST_GC_MIN (HZ/10) 23 #define DST_GC_INC (HZ/2) 24 #define DST_GC_MAX (120*HZ) 25 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. 31 */ 32 33 struct sk_buff; 34 35 struct dst_entry { 36 struct net_device *dev; 37 struct rcu_head rcu_head; 38 struct dst_entry *child; 39 struct dst_ops *ops; 40 unsigned long _metrics; 41 unsigned long expires; 42 struct dst_entry *path; 43 struct dst_entry *from; 44 #ifdef CONFIG_XFRM 45 struct xfrm_state *xfrm; 46 #else 47 void *__pad1; 48 #endif 49 int (*input)(struct sk_buff *); 50 int (*output)(struct net *net, struct sock *sk, struct sk_buff *skb); 51 52 unsigned short flags; 53 #define DST_HOST 0x0001 54 #define DST_NOXFRM 0x0002 55 #define DST_NOPOLICY 0x0004 56 #define DST_NOCOUNT 0x0008 57 #define DST_FAKE_RTABLE 0x0010 58 #define DST_XFRM_TUNNEL 0x0020 59 #define DST_XFRM_QUEUE 0x0040 60 #define DST_METADATA 0x0080 61 62 short error; 63 64 /* A non-zero value of dst->obsolete forces by-hand validation 65 * of the route entry. Positive values are set by the generic 66 * dst layer to indicate that the entry has been forcefully 67 * destroyed. 68 * 69 * Negative values are used by the implementation layer code to 70 * force invocation of the dst_ops->check() method. 71 */ 72 short obsolete; 73 #define DST_OBSOLETE_NONE 0 74 #define DST_OBSOLETE_DEAD 2 75 #define DST_OBSOLETE_FORCE_CHK -1 76 #define DST_OBSOLETE_KILL -2 77 unsigned short header_len; /* more space at head required */ 78 unsigned short trailer_len; /* space to reserve at tail */ 79 unsigned short __pad3; 80 81 #ifdef CONFIG_IP_ROUTE_CLASSID 82 __u32 tclassid; 83 #else 84 __u32 __pad2; 85 #endif 86 87 #ifdef CONFIG_64BIT 88 /* 89 * Align __refcnt to a 64 bytes alignment 90 * (L1_CACHE_SIZE would be too much) 91 */ 92 long __pad_to_align_refcnt[2]; 93 #endif 94 /* 95 * __refcnt wants to be on a different cache line from 96 * input/output/ops or performance tanks badly 97 */ 98 atomic_t __refcnt; /* client references */ 99 int __use; 100 unsigned long lastuse; 101 struct lwtunnel_state *lwtstate; 102 union { 103 struct dst_entry *next; 104 struct rtable __rcu *rt_next; 105 struct rt6_info *rt6_next; 106 struct dn_route __rcu *dn_next; 107 }; 108 }; 109 110 struct dst_metrics { 111 u32 metrics[RTAX_MAX]; 112 refcount_t refcnt; 113 }; 114 extern const struct dst_metrics dst_default_metrics; 115 116 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old); 117 118 #define DST_METRICS_READ_ONLY 0x1UL 119 #define DST_METRICS_REFCOUNTED 0x2UL 120 #define DST_METRICS_FLAGS 0x3UL 121 #define __DST_METRICS_PTR(Y) \ 122 ((u32 *)((Y) & ~DST_METRICS_FLAGS)) 123 #define DST_METRICS_PTR(X) __DST_METRICS_PTR((X)->_metrics) 124 125 static inline bool dst_metrics_read_only(const struct dst_entry *dst) 126 { 127 return dst->_metrics & DST_METRICS_READ_ONLY; 128 } 129 130 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old); 131 132 static inline void dst_destroy_metrics_generic(struct dst_entry *dst) 133 { 134 unsigned long val = dst->_metrics; 135 if (!(val & DST_METRICS_READ_ONLY)) 136 __dst_destroy_metrics_generic(dst, val); 137 } 138 139 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst) 140 { 141 unsigned long p = dst->_metrics; 142 143 BUG_ON(!p); 144 145 if (p & DST_METRICS_READ_ONLY) 146 return dst->ops->cow_metrics(dst, p); 147 return __DST_METRICS_PTR(p); 148 } 149 150 /* This may only be invoked before the entry has reached global 151 * visibility. 152 */ 153 static inline void dst_init_metrics(struct dst_entry *dst, 154 const u32 *src_metrics, 155 bool read_only) 156 { 157 dst->_metrics = ((unsigned long) src_metrics) | 158 (read_only ? DST_METRICS_READ_ONLY : 0); 159 } 160 161 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src) 162 { 163 u32 *dst_metrics = dst_metrics_write_ptr(dest); 164 165 if (dst_metrics) { 166 u32 *src_metrics = DST_METRICS_PTR(src); 167 168 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32)); 169 } 170 } 171 172 static inline u32 *dst_metrics_ptr(struct dst_entry *dst) 173 { 174 return DST_METRICS_PTR(dst); 175 } 176 177 static inline u32 178 dst_metric_raw(const struct dst_entry *dst, const int metric) 179 { 180 u32 *p = DST_METRICS_PTR(dst); 181 182 return p[metric-1]; 183 } 184 185 static inline u32 186 dst_metric(const struct dst_entry *dst, const int metric) 187 { 188 WARN_ON_ONCE(metric == RTAX_HOPLIMIT || 189 metric == RTAX_ADVMSS || 190 metric == RTAX_MTU); 191 return dst_metric_raw(dst, metric); 192 } 193 194 static inline u32 195 dst_metric_advmss(const struct dst_entry *dst) 196 { 197 u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS); 198 199 if (!advmss) 200 advmss = dst->ops->default_advmss(dst); 201 202 return advmss; 203 } 204 205 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val) 206 { 207 u32 *p = dst_metrics_write_ptr(dst); 208 209 if (p) 210 p[metric-1] = val; 211 } 212 213 /* Kernel-internal feature bits that are unallocated in user space. */ 214 #define DST_FEATURE_ECN_CA (1 << 31) 215 216 #define DST_FEATURE_MASK (DST_FEATURE_ECN_CA) 217 #define DST_FEATURE_ECN_MASK (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN) 218 219 static inline u32 220 dst_feature(const struct dst_entry *dst, u32 feature) 221 { 222 return dst_metric(dst, RTAX_FEATURES) & feature; 223 } 224 225 static inline u32 dst_mtu(const struct dst_entry *dst) 226 { 227 return dst->ops->mtu(dst); 228 } 229 230 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */ 231 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric) 232 { 233 return msecs_to_jiffies(dst_metric(dst, metric)); 234 } 235 236 static inline u32 237 dst_allfrag(const struct dst_entry *dst) 238 { 239 int ret = dst_feature(dst, RTAX_FEATURE_ALLFRAG); 240 return ret; 241 } 242 243 static inline int 244 dst_metric_locked(const struct dst_entry *dst, int metric) 245 { 246 return dst_metric(dst, RTAX_LOCK) & (1<<metric); 247 } 248 249 static inline void dst_hold(struct dst_entry *dst) 250 { 251 /* 252 * If your kernel compilation stops here, please check 253 * __pad_to_align_refcnt declaration in struct dst_entry 254 */ 255 BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63); 256 WARN_ON(atomic_inc_not_zero(&dst->__refcnt) == 0); 257 } 258 259 static inline void dst_use(struct dst_entry *dst, unsigned long time) 260 { 261 dst_hold(dst); 262 dst->__use++; 263 dst->lastuse = time; 264 } 265 266 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time) 267 { 268 dst->__use++; 269 dst->lastuse = time; 270 } 271 272 static inline struct dst_entry *dst_clone(struct dst_entry *dst) 273 { 274 if (dst) 275 dst_hold(dst); 276 return dst; 277 } 278 279 void dst_release(struct dst_entry *dst); 280 281 void dst_release_immediate(struct dst_entry *dst); 282 283 static inline void refdst_drop(unsigned long refdst) 284 { 285 if (!(refdst & SKB_DST_NOREF)) 286 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK)); 287 } 288 289 /** 290 * skb_dst_drop - drops skb dst 291 * @skb: buffer 292 * 293 * Drops dst reference count if a reference was taken. 294 */ 295 static inline void skb_dst_drop(struct sk_buff *skb) 296 { 297 if (skb->_skb_refdst) { 298 refdst_drop(skb->_skb_refdst); 299 skb->_skb_refdst = 0UL; 300 } 301 } 302 303 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst) 304 { 305 nskb->_skb_refdst = refdst; 306 if (!(nskb->_skb_refdst & SKB_DST_NOREF)) 307 dst_clone(skb_dst(nskb)); 308 } 309 310 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb) 311 { 312 __skb_dst_copy(nskb, oskb->_skb_refdst); 313 } 314 315 /** 316 * dst_hold_safe - Take a reference on a dst if possible 317 * @dst: pointer to dst entry 318 * 319 * This helper returns false if it could not safely 320 * take a reference on a dst. 321 */ 322 static inline bool dst_hold_safe(struct dst_entry *dst) 323 { 324 return atomic_inc_not_zero(&dst->__refcnt); 325 } 326 327 /** 328 * skb_dst_force - makes sure skb dst is refcounted 329 * @skb: buffer 330 * 331 * If dst is not yet refcounted and not destroyed, grab a ref on it. 332 */ 333 static inline void skb_dst_force(struct sk_buff *skb) 334 { 335 if (skb_dst_is_noref(skb)) { 336 struct dst_entry *dst = skb_dst(skb); 337 338 WARN_ON(!rcu_read_lock_held()); 339 if (!dst_hold_safe(dst)) 340 dst = NULL; 341 342 skb->_skb_refdst = (unsigned long)dst; 343 } 344 } 345 346 347 /** 348 * __skb_tunnel_rx - prepare skb for rx reinsert 349 * @skb: buffer 350 * @dev: tunnel device 351 * @net: netns for packet i/o 352 * 353 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 354 * so make some cleanups. (no accounting done) 355 */ 356 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev, 357 struct net *net) 358 { 359 skb->dev = dev; 360 361 /* 362 * Clear hash so that we can recalulate the hash for the 363 * encapsulated packet, unless we have already determine the hash 364 * over the L4 4-tuple. 365 */ 366 skb_clear_hash_if_not_l4(skb); 367 skb_set_queue_mapping(skb, 0); 368 skb_scrub_packet(skb, !net_eq(net, dev_net(dev))); 369 } 370 371 /** 372 * skb_tunnel_rx - prepare skb for rx reinsert 373 * @skb: buffer 374 * @dev: tunnel device 375 * 376 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 377 * so make some cleanups, and perform accounting. 378 * Note: this accounting is not SMP safe. 379 */ 380 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev, 381 struct net *net) 382 { 383 /* TODO : stats should be SMP safe */ 384 dev->stats.rx_packets++; 385 dev->stats.rx_bytes += skb->len; 386 __skb_tunnel_rx(skb, dev, net); 387 } 388 389 static inline u32 dst_tclassid(const struct sk_buff *skb) 390 { 391 #ifdef CONFIG_IP_ROUTE_CLASSID 392 const struct dst_entry *dst; 393 394 dst = skb_dst(skb); 395 if (dst) 396 return dst->tclassid; 397 #endif 398 return 0; 399 } 400 401 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb); 402 static inline int dst_discard(struct sk_buff *skb) 403 { 404 return dst_discard_out(&init_net, skb->sk, skb); 405 } 406 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref, 407 int initial_obsolete, unsigned short flags); 408 void dst_init(struct dst_entry *dst, struct dst_ops *ops, 409 struct net_device *dev, int initial_ref, int initial_obsolete, 410 unsigned short flags); 411 struct dst_entry *dst_destroy(struct dst_entry *dst); 412 void dst_dev_put(struct dst_entry *dst); 413 414 static inline void dst_confirm(struct dst_entry *dst) 415 { 416 } 417 418 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr) 419 { 420 struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr); 421 return IS_ERR(n) ? NULL : n; 422 } 423 424 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst, 425 struct sk_buff *skb) 426 { 427 struct neighbour *n = dst->ops->neigh_lookup(dst, skb, NULL); 428 return IS_ERR(n) ? NULL : n; 429 } 430 431 static inline void dst_confirm_neigh(const struct dst_entry *dst, 432 const void *daddr) 433 { 434 if (dst->ops->confirm_neigh) 435 dst->ops->confirm_neigh(dst, daddr); 436 } 437 438 static inline void dst_link_failure(struct sk_buff *skb) 439 { 440 struct dst_entry *dst = skb_dst(skb); 441 if (dst && dst->ops && dst->ops->link_failure) 442 dst->ops->link_failure(skb); 443 } 444 445 static inline void dst_set_expires(struct dst_entry *dst, int timeout) 446 { 447 unsigned long expires = jiffies + timeout; 448 449 if (expires == 0) 450 expires = 1; 451 452 if (dst->expires == 0 || time_before(expires, dst->expires)) 453 dst->expires = expires; 454 } 455 456 /* Output packet to network from transport. */ 457 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb) 458 { 459 return skb_dst(skb)->output(net, sk, skb); 460 } 461 462 /* Input packet from network to transport. */ 463 static inline int dst_input(struct sk_buff *skb) 464 { 465 return skb_dst(skb)->input(skb); 466 } 467 468 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) 469 { 470 if (dst->obsolete) 471 dst = dst->ops->check(dst, cookie); 472 return dst; 473 } 474 475 /* Flags for xfrm_lookup flags argument. */ 476 enum { 477 XFRM_LOOKUP_ICMP = 1 << 0, 478 XFRM_LOOKUP_QUEUE = 1 << 1, 479 XFRM_LOOKUP_KEEP_DST_REF = 1 << 2, 480 }; 481 482 struct flowi; 483 #ifndef CONFIG_XFRM 484 static inline struct dst_entry *xfrm_lookup(struct net *net, 485 struct dst_entry *dst_orig, 486 const struct flowi *fl, 487 const struct sock *sk, 488 int flags) 489 { 490 return dst_orig; 491 } 492 493 static inline struct dst_entry *xfrm_lookup_route(struct net *net, 494 struct dst_entry *dst_orig, 495 const struct flowi *fl, 496 const struct sock *sk, 497 int flags) 498 { 499 return dst_orig; 500 } 501 502 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst) 503 { 504 return NULL; 505 } 506 507 #else 508 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig, 509 const struct flowi *fl, const struct sock *sk, 510 int flags); 511 512 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig, 513 const struct flowi *fl, const struct sock *sk, 514 int flags); 515 516 /* skb attached with this dst needs transformation if dst->xfrm is valid */ 517 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst) 518 { 519 return dst->xfrm; 520 } 521 #endif 522 523 #endif /* _NET_DST_H */ 524