1 /* 2 * net/dst.h Protocol independent destination cache definitions. 3 * 4 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> 5 * 6 */ 7 8 #ifndef _NET_DST_H 9 #define _NET_DST_H 10 11 #include <net/dst_ops.h> 12 #include <linux/netdevice.h> 13 #include <linux/rtnetlink.h> 14 #include <linux/rcupdate.h> 15 #include <linux/bug.h> 16 #include <linux/jiffies.h> 17 #include <net/neighbour.h> 18 #include <asm/processor.h> 19 20 #define DST_GC_MIN (HZ/10) 21 #define DST_GC_INC (HZ/2) 22 #define DST_GC_MAX (120*HZ) 23 24 /* Each dst_entry has reference count and sits in some parent list(s). 25 * When it is removed from parent list, it is "freed" (dst_free). 26 * After this it enters dead state (dst->obsolete > 0) and if its refcnt 27 * is zero, it can be destroyed immediately, otherwise it is added 28 * to gc list and garbage collector periodically checks the refcnt. 29 */ 30 31 struct sk_buff; 32 33 struct dst_entry { 34 struct rcu_head rcu_head; 35 struct dst_entry *child; 36 struct net_device *dev; 37 struct dst_ops *ops; 38 unsigned long _metrics; 39 unsigned long expires; 40 struct dst_entry *path; 41 struct dst_entry *from; 42 #ifdef CONFIG_XFRM 43 struct xfrm_state *xfrm; 44 #else 45 void *__pad1; 46 #endif 47 int (*input)(struct sk_buff *); 48 int (*output)(struct net *net, struct sock *sk, struct sk_buff *skb); 49 50 unsigned short flags; 51 #define DST_HOST 0x0001 52 #define DST_NOXFRM 0x0002 53 #define DST_NOPOLICY 0x0004 54 #define DST_NOHASH 0x0008 55 #define DST_NOCACHE 0x0010 56 #define DST_NOCOUNT 0x0020 57 #define DST_FAKE_RTABLE 0x0040 58 #define DST_XFRM_TUNNEL 0x0080 59 #define DST_XFRM_QUEUE 0x0100 60 #define DST_METADATA 0x0200 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 atomic_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 atomic_inc(&dst->__refcnt); 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 atomic_inc(&dst->__refcnt); 276 return dst; 277 } 278 279 void dst_release(struct dst_entry *dst); 280 281 static inline void refdst_drop(unsigned long refdst) 282 { 283 if (!(refdst & SKB_DST_NOREF)) 284 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK)); 285 } 286 287 /** 288 * skb_dst_drop - drops skb dst 289 * @skb: buffer 290 * 291 * Drops dst reference count if a reference was taken. 292 */ 293 static inline void skb_dst_drop(struct sk_buff *skb) 294 { 295 if (skb->_skb_refdst) { 296 refdst_drop(skb->_skb_refdst); 297 skb->_skb_refdst = 0UL; 298 } 299 } 300 301 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst) 302 { 303 nskb->_skb_refdst = refdst; 304 if (!(nskb->_skb_refdst & SKB_DST_NOREF)) 305 dst_clone(skb_dst(nskb)); 306 } 307 308 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb) 309 { 310 __skb_dst_copy(nskb, oskb->_skb_refdst); 311 } 312 313 /** 314 * skb_dst_force - makes sure skb dst is refcounted 315 * @skb: buffer 316 * 317 * If dst is not yet refcounted, let's do it 318 */ 319 static inline void skb_dst_force(struct sk_buff *skb) 320 { 321 if (skb_dst_is_noref(skb)) { 322 WARN_ON(!rcu_read_lock_held()); 323 skb->_skb_refdst &= ~SKB_DST_NOREF; 324 dst_clone(skb_dst(skb)); 325 } 326 } 327 328 /** 329 * dst_hold_safe - Take a reference on a dst if possible 330 * @dst: pointer to dst entry 331 * 332 * This helper returns false if it could not safely 333 * take a reference on a dst. 334 */ 335 static inline bool dst_hold_safe(struct dst_entry *dst) 336 { 337 if (dst->flags & DST_NOCACHE) 338 return atomic_inc_not_zero(&dst->__refcnt); 339 dst_hold(dst); 340 return true; 341 } 342 343 /** 344 * skb_dst_force_safe - makes sure skb dst is refcounted 345 * @skb: buffer 346 * 347 * If dst is not yet refcounted and not destroyed, grab a ref on it. 348 */ 349 static inline void skb_dst_force_safe(struct sk_buff *skb) 350 { 351 if (skb_dst_is_noref(skb)) { 352 struct dst_entry *dst = skb_dst(skb); 353 354 if (!dst_hold_safe(dst)) 355 dst = NULL; 356 357 skb->_skb_refdst = (unsigned long)dst; 358 } 359 } 360 361 362 /** 363 * __skb_tunnel_rx - prepare skb for rx reinsert 364 * @skb: buffer 365 * @dev: tunnel device 366 * @net: netns for packet i/o 367 * 368 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 369 * so make some cleanups. (no accounting done) 370 */ 371 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev, 372 struct net *net) 373 { 374 skb->dev = dev; 375 376 /* 377 * Clear hash so that we can recalulate the hash for the 378 * encapsulated packet, unless we have already determine the hash 379 * over the L4 4-tuple. 380 */ 381 skb_clear_hash_if_not_l4(skb); 382 skb_set_queue_mapping(skb, 0); 383 skb_scrub_packet(skb, !net_eq(net, dev_net(dev))); 384 } 385 386 /** 387 * skb_tunnel_rx - prepare skb for rx reinsert 388 * @skb: buffer 389 * @dev: tunnel device 390 * 391 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 392 * so make some cleanups, and perform accounting. 393 * Note: this accounting is not SMP safe. 394 */ 395 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev, 396 struct net *net) 397 { 398 /* TODO : stats should be SMP safe */ 399 dev->stats.rx_packets++; 400 dev->stats.rx_bytes += skb->len; 401 __skb_tunnel_rx(skb, dev, net); 402 } 403 404 static inline u32 dst_tclassid(const struct sk_buff *skb) 405 { 406 #ifdef CONFIG_IP_ROUTE_CLASSID 407 const struct dst_entry *dst; 408 409 dst = skb_dst(skb); 410 if (dst) 411 return dst->tclassid; 412 #endif 413 return 0; 414 } 415 416 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb); 417 static inline int dst_discard(struct sk_buff *skb) 418 { 419 return dst_discard_out(&init_net, skb->sk, skb); 420 } 421 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref, 422 int initial_obsolete, unsigned short flags); 423 void dst_init(struct dst_entry *dst, struct dst_ops *ops, 424 struct net_device *dev, int initial_ref, int initial_obsolete, 425 unsigned short flags); 426 void __dst_free(struct dst_entry *dst); 427 struct dst_entry *dst_destroy(struct dst_entry *dst); 428 429 static inline void dst_free(struct dst_entry *dst) 430 { 431 if (dst->obsolete > 0) 432 return; 433 if (!atomic_read(&dst->__refcnt)) { 434 dst = dst_destroy(dst); 435 if (!dst) 436 return; 437 } 438 __dst_free(dst); 439 } 440 441 static inline void dst_rcu_free(struct rcu_head *head) 442 { 443 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head); 444 dst_free(dst); 445 } 446 447 static inline void dst_confirm(struct dst_entry *dst) 448 { 449 } 450 451 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr) 452 { 453 struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr); 454 return IS_ERR(n) ? NULL : n; 455 } 456 457 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst, 458 struct sk_buff *skb) 459 { 460 struct neighbour *n = dst->ops->neigh_lookup(dst, skb, NULL); 461 return IS_ERR(n) ? NULL : n; 462 } 463 464 static inline void dst_confirm_neigh(const struct dst_entry *dst, 465 const void *daddr) 466 { 467 if (dst->ops->confirm_neigh) 468 dst->ops->confirm_neigh(dst, daddr); 469 } 470 471 static inline void dst_link_failure(struct sk_buff *skb) 472 { 473 struct dst_entry *dst = skb_dst(skb); 474 if (dst && dst->ops && dst->ops->link_failure) 475 dst->ops->link_failure(skb); 476 } 477 478 static inline void dst_set_expires(struct dst_entry *dst, int timeout) 479 { 480 unsigned long expires = jiffies + timeout; 481 482 if (expires == 0) 483 expires = 1; 484 485 if (dst->expires == 0 || time_before(expires, dst->expires)) 486 dst->expires = expires; 487 } 488 489 /* Output packet to network from transport. */ 490 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb) 491 { 492 return skb_dst(skb)->output(net, sk, skb); 493 } 494 495 /* Input packet from network to transport. */ 496 static inline int dst_input(struct sk_buff *skb) 497 { 498 return skb_dst(skb)->input(skb); 499 } 500 501 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) 502 { 503 if (dst->obsolete) 504 dst = dst->ops->check(dst, cookie); 505 return dst; 506 } 507 508 void dst_subsys_init(void); 509 510 /* Flags for xfrm_lookup flags argument. */ 511 enum { 512 XFRM_LOOKUP_ICMP = 1 << 0, 513 XFRM_LOOKUP_QUEUE = 1 << 1, 514 XFRM_LOOKUP_KEEP_DST_REF = 1 << 2, 515 }; 516 517 struct flowi; 518 #ifndef CONFIG_XFRM 519 static inline struct dst_entry *xfrm_lookup(struct net *net, 520 struct dst_entry *dst_orig, 521 const struct flowi *fl, 522 const struct sock *sk, 523 int flags) 524 { 525 return dst_orig; 526 } 527 528 static inline struct dst_entry *xfrm_lookup_route(struct net *net, 529 struct dst_entry *dst_orig, 530 const struct flowi *fl, 531 const struct sock *sk, 532 int flags) 533 { 534 return dst_orig; 535 } 536 537 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst) 538 { 539 return NULL; 540 } 541 542 #else 543 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig, 544 const struct flowi *fl, const struct sock *sk, 545 int flags); 546 547 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig, 548 const struct flowi *fl, const struct sock *sk, 549 int flags); 550 551 /* skb attached with this dst needs transformation if dst->xfrm is valid */ 552 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst) 553 { 554 return dst->xfrm; 555 } 556 #endif 557 558 #endif /* _NET_DST_H */ 559