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 net_device *dev; 35 struct rcu_head rcu_head; 36 struct dst_entry *child; 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_NOCOUNT 0x0008 55 #define DST_FAKE_RTABLE 0x0010 56 #define DST_XFRM_TUNNEL 0x0020 57 #define DST_XFRM_QUEUE 0x0040 58 #define DST_METADATA 0x0080 59 60 short error; 61 62 /* A non-zero value of dst->obsolete forces by-hand validation 63 * of the route entry. Positive values are set by the generic 64 * dst layer to indicate that the entry has been forcefully 65 * destroyed. 66 * 67 * Negative values are used by the implementation layer code to 68 * force invocation of the dst_ops->check() method. 69 */ 70 short obsolete; 71 #define DST_OBSOLETE_NONE 0 72 #define DST_OBSOLETE_DEAD 2 73 #define DST_OBSOLETE_FORCE_CHK -1 74 #define DST_OBSOLETE_KILL -2 75 unsigned short header_len; /* more space at head required */ 76 unsigned short trailer_len; /* space to reserve at tail */ 77 unsigned short __pad3; 78 79 #ifdef CONFIG_IP_ROUTE_CLASSID 80 __u32 tclassid; 81 #else 82 __u32 __pad2; 83 #endif 84 85 #ifdef CONFIG_64BIT 86 /* 87 * Align __refcnt to a 64 bytes alignment 88 * (L1_CACHE_SIZE would be too much) 89 */ 90 long __pad_to_align_refcnt[2]; 91 #endif 92 /* 93 * __refcnt wants to be on a different cache line from 94 * input/output/ops or performance tanks badly 95 */ 96 atomic_t __refcnt; /* client references */ 97 int __use; 98 unsigned long lastuse; 99 struct lwtunnel_state *lwtstate; 100 union { 101 struct dst_entry *next; 102 struct rtable __rcu *rt_next; 103 struct rt6_info *rt6_next; 104 struct dn_route __rcu *dn_next; 105 }; 106 }; 107 108 struct dst_metrics { 109 u32 metrics[RTAX_MAX]; 110 atomic_t refcnt; 111 }; 112 extern const struct dst_metrics dst_default_metrics; 113 114 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old); 115 116 #define DST_METRICS_READ_ONLY 0x1UL 117 #define DST_METRICS_REFCOUNTED 0x2UL 118 #define DST_METRICS_FLAGS 0x3UL 119 #define __DST_METRICS_PTR(Y) \ 120 ((u32 *)((Y) & ~DST_METRICS_FLAGS)) 121 #define DST_METRICS_PTR(X) __DST_METRICS_PTR((X)->_metrics) 122 123 static inline bool dst_metrics_read_only(const struct dst_entry *dst) 124 { 125 return dst->_metrics & DST_METRICS_READ_ONLY; 126 } 127 128 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old); 129 130 static inline void dst_destroy_metrics_generic(struct dst_entry *dst) 131 { 132 unsigned long val = dst->_metrics; 133 if (!(val & DST_METRICS_READ_ONLY)) 134 __dst_destroy_metrics_generic(dst, val); 135 } 136 137 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst) 138 { 139 unsigned long p = dst->_metrics; 140 141 BUG_ON(!p); 142 143 if (p & DST_METRICS_READ_ONLY) 144 return dst->ops->cow_metrics(dst, p); 145 return __DST_METRICS_PTR(p); 146 } 147 148 /* This may only be invoked before the entry has reached global 149 * visibility. 150 */ 151 static inline void dst_init_metrics(struct dst_entry *dst, 152 const u32 *src_metrics, 153 bool read_only) 154 { 155 dst->_metrics = ((unsigned long) src_metrics) | 156 (read_only ? DST_METRICS_READ_ONLY : 0); 157 } 158 159 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src) 160 { 161 u32 *dst_metrics = dst_metrics_write_ptr(dest); 162 163 if (dst_metrics) { 164 u32 *src_metrics = DST_METRICS_PTR(src); 165 166 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32)); 167 } 168 } 169 170 static inline u32 *dst_metrics_ptr(struct dst_entry *dst) 171 { 172 return DST_METRICS_PTR(dst); 173 } 174 175 static inline u32 176 dst_metric_raw(const struct dst_entry *dst, const int metric) 177 { 178 u32 *p = DST_METRICS_PTR(dst); 179 180 return p[metric-1]; 181 } 182 183 static inline u32 184 dst_metric(const struct dst_entry *dst, const int metric) 185 { 186 WARN_ON_ONCE(metric == RTAX_HOPLIMIT || 187 metric == RTAX_ADVMSS || 188 metric == RTAX_MTU); 189 return dst_metric_raw(dst, metric); 190 } 191 192 static inline u32 193 dst_metric_advmss(const struct dst_entry *dst) 194 { 195 u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS); 196 197 if (!advmss) 198 advmss = dst->ops->default_advmss(dst); 199 200 return advmss; 201 } 202 203 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val) 204 { 205 u32 *p = dst_metrics_write_ptr(dst); 206 207 if (p) 208 p[metric-1] = val; 209 } 210 211 /* Kernel-internal feature bits that are unallocated in user space. */ 212 #define DST_FEATURE_ECN_CA (1 << 31) 213 214 #define DST_FEATURE_MASK (DST_FEATURE_ECN_CA) 215 #define DST_FEATURE_ECN_MASK (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN) 216 217 static inline u32 218 dst_feature(const struct dst_entry *dst, u32 feature) 219 { 220 return dst_metric(dst, RTAX_FEATURES) & feature; 221 } 222 223 static inline u32 dst_mtu(const struct dst_entry *dst) 224 { 225 return dst->ops->mtu(dst); 226 } 227 228 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */ 229 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric) 230 { 231 return msecs_to_jiffies(dst_metric(dst, metric)); 232 } 233 234 static inline u32 235 dst_allfrag(const struct dst_entry *dst) 236 { 237 int ret = dst_feature(dst, RTAX_FEATURE_ALLFRAG); 238 return ret; 239 } 240 241 static inline int 242 dst_metric_locked(const struct dst_entry *dst, int metric) 243 { 244 return dst_metric(dst, RTAX_LOCK) & (1<<metric); 245 } 246 247 static inline void dst_hold(struct dst_entry *dst) 248 { 249 /* 250 * If your kernel compilation stops here, please check 251 * __pad_to_align_refcnt declaration in struct dst_entry 252 */ 253 BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63); 254 WARN_ON(atomic_inc_not_zero(&dst->__refcnt) == 0); 255 } 256 257 static inline void dst_use(struct dst_entry *dst, unsigned long time) 258 { 259 dst_hold(dst); 260 dst->__use++; 261 dst->lastuse = time; 262 } 263 264 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time) 265 { 266 dst->__use++; 267 dst->lastuse = time; 268 } 269 270 static inline struct dst_entry *dst_clone(struct dst_entry *dst) 271 { 272 if (dst) 273 atomic_inc(&dst->__refcnt); 274 return dst; 275 } 276 277 void dst_release(struct dst_entry *dst); 278 279 void dst_release_immediate(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 return atomic_inc_not_zero(&dst->__refcnt); 338 } 339 340 /** 341 * skb_dst_force_safe - makes sure skb dst is refcounted 342 * @skb: buffer 343 * 344 * If dst is not yet refcounted and not destroyed, grab a ref on it. 345 */ 346 static inline void skb_dst_force_safe(struct sk_buff *skb) 347 { 348 if (skb_dst_is_noref(skb)) { 349 struct dst_entry *dst = skb_dst(skb); 350 351 if (!dst_hold_safe(dst)) 352 dst = NULL; 353 354 skb->_skb_refdst = (unsigned long)dst; 355 } 356 } 357 358 359 /** 360 * __skb_tunnel_rx - prepare skb for rx reinsert 361 * @skb: buffer 362 * @dev: tunnel device 363 * @net: netns for packet i/o 364 * 365 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 366 * so make some cleanups. (no accounting done) 367 */ 368 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev, 369 struct net *net) 370 { 371 skb->dev = dev; 372 373 /* 374 * Clear hash so that we can recalulate the hash for the 375 * encapsulated packet, unless we have already determine the hash 376 * over the L4 4-tuple. 377 */ 378 skb_clear_hash_if_not_l4(skb); 379 skb_set_queue_mapping(skb, 0); 380 skb_scrub_packet(skb, !net_eq(net, dev_net(dev))); 381 } 382 383 /** 384 * skb_tunnel_rx - prepare skb for rx reinsert 385 * @skb: buffer 386 * @dev: tunnel device 387 * 388 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 389 * so make some cleanups, and perform accounting. 390 * Note: this accounting is not SMP safe. 391 */ 392 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev, 393 struct net *net) 394 { 395 /* TODO : stats should be SMP safe */ 396 dev->stats.rx_packets++; 397 dev->stats.rx_bytes += skb->len; 398 __skb_tunnel_rx(skb, dev, net); 399 } 400 401 static inline u32 dst_tclassid(const struct sk_buff *skb) 402 { 403 #ifdef CONFIG_IP_ROUTE_CLASSID 404 const struct dst_entry *dst; 405 406 dst = skb_dst(skb); 407 if (dst) 408 return dst->tclassid; 409 #endif 410 return 0; 411 } 412 413 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb); 414 static inline int dst_discard(struct sk_buff *skb) 415 { 416 return dst_discard_out(&init_net, skb->sk, skb); 417 } 418 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref, 419 int initial_obsolete, unsigned short flags); 420 void dst_init(struct dst_entry *dst, struct dst_ops *ops, 421 struct net_device *dev, int initial_ref, int initial_obsolete, 422 unsigned short flags); 423 struct dst_entry *dst_destroy(struct dst_entry *dst); 424 void dst_dev_put(struct dst_entry *dst); 425 426 static inline void dst_confirm(struct dst_entry *dst) 427 { 428 } 429 430 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr) 431 { 432 struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr); 433 return IS_ERR(n) ? NULL : n; 434 } 435 436 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst, 437 struct sk_buff *skb) 438 { 439 struct neighbour *n = dst->ops->neigh_lookup(dst, skb, NULL); 440 return IS_ERR(n) ? NULL : n; 441 } 442 443 static inline void dst_confirm_neigh(const struct dst_entry *dst, 444 const void *daddr) 445 { 446 if (dst->ops->confirm_neigh) 447 dst->ops->confirm_neigh(dst, daddr); 448 } 449 450 static inline void dst_link_failure(struct sk_buff *skb) 451 { 452 struct dst_entry *dst = skb_dst(skb); 453 if (dst && dst->ops && dst->ops->link_failure) 454 dst->ops->link_failure(skb); 455 } 456 457 static inline void dst_set_expires(struct dst_entry *dst, int timeout) 458 { 459 unsigned long expires = jiffies + timeout; 460 461 if (expires == 0) 462 expires = 1; 463 464 if (dst->expires == 0 || time_before(expires, dst->expires)) 465 dst->expires = expires; 466 } 467 468 /* Output packet to network from transport. */ 469 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb) 470 { 471 return skb_dst(skb)->output(net, sk, skb); 472 } 473 474 /* Input packet from network to transport. */ 475 static inline int dst_input(struct sk_buff *skb) 476 { 477 return skb_dst(skb)->input(skb); 478 } 479 480 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) 481 { 482 if (dst->obsolete) 483 dst = dst->ops->check(dst, cookie); 484 return dst; 485 } 486 487 /* Flags for xfrm_lookup flags argument. */ 488 enum { 489 XFRM_LOOKUP_ICMP = 1 << 0, 490 XFRM_LOOKUP_QUEUE = 1 << 1, 491 XFRM_LOOKUP_KEEP_DST_REF = 1 << 2, 492 }; 493 494 struct flowi; 495 #ifndef CONFIG_XFRM 496 static inline struct dst_entry *xfrm_lookup(struct net *net, 497 struct dst_entry *dst_orig, 498 const struct flowi *fl, 499 const struct sock *sk, 500 int flags) 501 { 502 return dst_orig; 503 } 504 505 static inline struct dst_entry *xfrm_lookup_route(struct net *net, 506 struct dst_entry *dst_orig, 507 const struct flowi *fl, 508 const struct sock *sk, 509 int flags) 510 { 511 return dst_orig; 512 } 513 514 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst) 515 { 516 return NULL; 517 } 518 519 #else 520 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig, 521 const struct flowi *fl, const struct sock *sk, 522 int flags); 523 524 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig, 525 const struct flowi *fl, const struct sock *sk, 526 int flags); 527 528 /* skb attached with this dst needs transformation if dst->xfrm is valid */ 529 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst) 530 { 531 return dst->xfrm; 532 } 533 #endif 534 535 #endif /* _NET_DST_H */ 536