include/net/dst.h

   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         unsigned short          pending_confirm;
  63
  64         short                   error;
  65
  66         /* A non-zero value of dst->obsolete forces by-hand validation
  67          * of the route entry.  Positive values are set by the generic
  68          * dst layer to indicate that the entry has been forcefully
  69          * destroyed.
  70          *
  71          * Negative values are used by the implementation layer code to
  72          * force invocation of the dst_ops->check() method.
  73          */
  74         short                   obsolete;
  75 #define DST_OBSOLETE_NONE       0
  76 #define DST_OBSOLETE_DEAD       2
  77 #define DST_OBSOLETE_FORCE_CHK  -1
  78 #define DST_OBSOLETE_KILL       -2
  79         unsigned short          header_len;     /* more space at head required */
  80         unsigned short          trailer_len;    /* space to reserve at tail */
  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 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
 111 extern const u32 dst_default_metrics[];
 112
 113 #define DST_METRICS_READ_ONLY           0x1UL
 114 #define DST_METRICS_FLAGS               0x3UL
 115 #define __DST_METRICS_PTR(Y)    \
 116         ((u32 *)((Y) & ~DST_METRICS_FLAGS))
 117 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
 118
 119 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
 120 {
 121         return dst->_metrics & DST_METRICS_READ_ONLY;
 122 }
 123
 124 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
 125
 126 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
 127 {
 128         unsigned long val = dst->_metrics;
 129         if (!(val & DST_METRICS_READ_ONLY))
 130                 __dst_destroy_metrics_generic(dst, val);
 131 }
 132
 133 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
 134 {
 135         unsigned long p = dst->_metrics;
 136
 137         BUG_ON(!p);
 138
 139         if (p & DST_METRICS_READ_ONLY)
 140                 return dst->ops->cow_metrics(dst, p);
 141         return __DST_METRICS_PTR(p);
 142 }
 143
 144 /* This may only be invoked before the entry has reached global
 145  * visibility.
 146  */
 147 static inline void dst_init_metrics(struct dst_entry *dst,
 148                                     const u32 *src_metrics,
 149                                     bool read_only)
 150 {
 151         dst->_metrics = ((unsigned long) src_metrics) |
 152                 (read_only ? DST_METRICS_READ_ONLY : 0);
 153 }
 154
 155 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
 156 {
 157         u32 *dst_metrics = dst_metrics_write_ptr(dest);
 158
 159         if (dst_metrics) {
 160                 u32 *src_metrics = DST_METRICS_PTR(src);
 161
 162                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
 163         }
 164 }
 165
 166 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
 167 {
 168         return DST_METRICS_PTR(dst);
 169 }
 170
 171 static inline u32
 172 dst_metric_raw(const struct dst_entry *dst, const int metric)
 173 {
 174         u32 *p = DST_METRICS_PTR(dst);
 175
 176         return p[metric-1];
 177 }
 178
 179 static inline u32
 180 dst_metric(const struct dst_entry *dst, const int metric)
 181 {
 182         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
 183                      metric == RTAX_ADVMSS ||
 184                      metric == RTAX_MTU);
 185         return dst_metric_raw(dst, metric);
 186 }
 187
 188 static inline u32
 189 dst_metric_advmss(const struct dst_entry *dst)
 190 {
 191         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
 192
 193         if (!advmss)
 194                 advmss = dst->ops->default_advmss(dst);
 195
 196         return advmss;
 197 }
 198
 199 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
 200 {
 201         u32 *p = dst_metrics_write_ptr(dst);
 202
 203         if (p)
 204                 p[metric-1] = val;
 205 }
 206
 207 /* Kernel-internal feature bits that are unallocated in user space. */
 208 #define DST_FEATURE_ECN_CA      (1 << 31)
 209
 210 #define DST_FEATURE_MASK        (DST_FEATURE_ECN_CA)
 211 #define DST_FEATURE_ECN_MASK    (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN)
 212
 213 static inline u32
 214 dst_feature(const struct dst_entry *dst, u32 feature)
 215 {
 216         return dst_metric(dst, RTAX_FEATURES) & feature;
 217 }
 218
 219 static inline u32 dst_mtu(const struct dst_entry *dst)
 220 {
 221         return dst->ops->mtu(dst);
 222 }
 223
 224 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 225 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 226 {
 227         return msecs_to_jiffies(dst_metric(dst, metric));
 228 }
 229
 230 static inline u32
 231 dst_allfrag(const struct dst_entry *dst)
 232 {
 233         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
 234         return ret;
 235 }
 236
 237 static inline int
 238 dst_metric_locked(const struct dst_entry *dst, int metric)
 239 {
 240         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 241 }
 242
 243 static inline void dst_hold(struct dst_entry *dst)
 244 {
 245         /*
 246          * If your kernel compilation stops here, please check
 247          * __pad_to_align_refcnt declaration in struct dst_entry
 248          */
 249         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 250         atomic_inc(&dst->__refcnt);
 251 }
 252
 253 static inline void dst_use(struct dst_entry *dst, unsigned long time)
 254 {
 255         dst_hold(dst);
 256         dst->__use++;
 257         dst->lastuse = time;
 258 }
 259
 260 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
 261 {
 262         dst->__use++;
 263         dst->lastuse = time;
 264 }
 265
 266 static inline struct dst_entry *dst_clone(struct dst_entry *dst)
 267 {
 268         if (dst)
 269                 atomic_inc(&dst->__refcnt);
 270         return dst;
 271 }
 272
 273 void dst_release(struct dst_entry *dst);
 274
 275 static inline void refdst_drop(unsigned long refdst)
 276 {
 277         if (!(refdst & SKB_DST_NOREF))
 278                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 279 }
 280
 281 /**
 282  * skb_dst_drop - drops skb dst
 283  * @skb: buffer
 284  *
 285  * Drops dst reference count if a reference was taken.
 286  */
 287 static inline void skb_dst_drop(struct sk_buff *skb)
 288 {
 289         if (skb->_skb_refdst) {
 290                 refdst_drop(skb->_skb_refdst);
 291                 skb->_skb_refdst = 0UL;
 292         }
 293 }
 294
 295 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst)
 296 {
 297         nskb->_skb_refdst = refdst;
 298         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 299                 dst_clone(skb_dst(nskb));
 300 }
 301
 302 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 303 {
 304         __skb_dst_copy(nskb, oskb->_skb_refdst);
 305 }
 306
 307 /**
 308  * skb_dst_force - makes sure skb dst is refcounted
 309  * @skb: buffer
 310  *
 311  * If dst is not yet refcounted, let's do it
 312  */
 313 static inline void skb_dst_force(struct sk_buff *skb)
 314 {
 315         if (skb_dst_is_noref(skb)) {
 316                 WARN_ON(!rcu_read_lock_held());
 317                 skb->_skb_refdst &= ~SKB_DST_NOREF;
 318                 dst_clone(skb_dst(skb));
 319         }
 320 }
 321
 322 /**
 323  * dst_hold_safe - Take a reference on a dst if possible
 324  * @dst: pointer to dst entry
 325  *
 326  * This helper returns false if it could not safely
 327  * take a reference on a dst.
 328  */
 329 static inline bool dst_hold_safe(struct dst_entry *dst)
 330 {
 331         if (dst->flags & DST_NOCACHE)
 332                 return atomic_inc_not_zero(&dst->__refcnt);
 333         dst_hold(dst);
 334         return true;
 335 }
 336
 337 /**
 338  * skb_dst_force_safe - makes sure skb dst is refcounted
 339  * @skb: buffer
 340  *
 341  * If dst is not yet refcounted and not destroyed, grab a ref on it.
 342  */
 343 static inline void skb_dst_force_safe(struct sk_buff *skb)
 344 {
 345         if (skb_dst_is_noref(skb)) {
 346                 struct dst_entry *dst = skb_dst(skb);
 347
 348                 if (!dst_hold_safe(dst))
 349                         dst = NULL;
 350
 351                 skb->_skb_refdst = (unsigned long)dst;
 352         }
 353 }
 354
 355
 356 /**
 357  *      __skb_tunnel_rx - prepare skb for rx reinsert
 358  *      @skb: buffer
 359  *      @dev: tunnel device
 360  *      @net: netns for packet i/o
 361  *
 362  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 363  *      so make some cleanups. (no accounting done)
 364  */
 365 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 366                                    struct net *net)
 367 {
 368         skb->dev = dev;
 369
 370         /*
 371          * Clear hash so that we can recalulate the hash for the
 372          * encapsulated packet, unless we have already determine the hash
 373          * over the L4 4-tuple.
 374          */
 375         skb_clear_hash_if_not_l4(skb);
 376         skb_set_queue_mapping(skb, 0);
 377         skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
 378 }
 379
 380 /**
 381  *      skb_tunnel_rx - prepare skb for rx reinsert
 382  *      @skb: buffer
 383  *      @dev: tunnel device
 384  *
 385  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 386  *      so make some cleanups, and perform accounting.
 387  *      Note: this accounting is not SMP safe.
 388  */
 389 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 390                                  struct net *net)
 391 {
 392         /* TODO : stats should be SMP safe */
 393         dev->stats.rx_packets++;
 394         dev->stats.rx_bytes += skb->len;
 395         __skb_tunnel_rx(skb, dev, net);
 396 }
 397
 398 static inline u32 dst_tclassid(const struct sk_buff *skb)
 399 {
 400 #ifdef CONFIG_IP_ROUTE_CLASSID
 401         const struct dst_entry *dst;
 402
 403         dst = skb_dst(skb);
 404         if (dst)
 405                 return dst->tclassid;
 406 #endif
 407         return 0;
 408 }
 409
 410 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
 411 static inline int dst_discard(struct sk_buff *skb)
 412 {
 413         return dst_discard_out(&init_net, skb->sk, skb);
 414 }
 415 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref,
 416                 int initial_obsolete, unsigned short flags);
 417 void dst_init(struct dst_entry *dst, struct dst_ops *ops,
 418               struct net_device *dev, int initial_ref, int initial_obsolete,
 419               unsigned short flags);
 420 void __dst_free(struct dst_entry *dst);
 421 struct dst_entry *dst_destroy(struct dst_entry *dst);
 422
 423 static inline void dst_free(struct dst_entry *dst)
 424 {
 425         if (dst->obsolete > 0)
 426                 return;
 427         if (!atomic_read(&dst->__refcnt)) {
 428                 dst = dst_destroy(dst);
 429                 if (!dst)
 430                         return;
 431         }
 432         __dst_free(dst);
 433 }
 434
 435 static inline void dst_rcu_free(struct rcu_head *head)
 436 {
 437         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 438         dst_free(dst);
 439 }
 440
 441 static inline void dst_confirm(struct dst_entry *dst)
 442 {
 443         dst->pending_confirm = 1;
 444 }
 445
 446 static inline int dst_neigh_output(struct dst_entry *dst, struct neighbour *n,
 447                                    struct sk_buff *skb)
 448 {
 449         const struct hh_cache *hh;
 450
 451         if (dst->pending_confirm) {
 452                 unsigned long now = jiffies;
 453
 454                 dst->pending_confirm = 0;
 455                 /* avoid dirtying neighbour */
 456                 if (n->confirmed != now)
 457                         n->confirmed = now;
 458         }
 459
 460         hh = &n->hh;
 461         if ((n->nud_state & NUD_CONNECTED) && hh->hh_len)
 462                 return neigh_hh_output(hh, skb);
 463         else
 464                 return n->output(n, skb);
 465 }
 466
 467 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
 468 {
 469         struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
 470         return IS_ERR(n) ? NULL : n;
 471 }
 472
 473 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
 474                                                      struct sk_buff *skb)
 475 {
 476         struct neighbour *n =  dst->ops->neigh_lookup(dst, skb, NULL);
 477         return IS_ERR(n) ? NULL : n;
 478 }
 479
 480 static inline void dst_link_failure(struct sk_buff *skb)
 481 {
 482         struct dst_entry *dst = skb_dst(skb);
 483         if (dst && dst->ops && dst->ops->link_failure)
 484                 dst->ops->link_failure(skb);
 485 }
 486
 487 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 488 {
 489         unsigned long expires = jiffies + timeout;
 490
 491         if (expires == 0)
 492                 expires = 1;
 493
 494         if (dst->expires == 0 || time_before(expires, dst->expires))
 495                 dst->expires = expires;
 496 }
 497
 498 /* Output packet to network from transport.  */
 499 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 500 {
 501         return skb_dst(skb)->output(net, sk, skb);
 502 }
 503
 504 /* Input packet from network to transport.  */
 505 static inline int dst_input(struct sk_buff *skb)
 506 {
 507         return skb_dst(skb)->input(skb);
 508 }
 509
 510 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 511 {
 512         if (dst->obsolete)
 513                 dst = dst->ops->check(dst, cookie);
 514         return dst;
 515 }
 516
 517 void dst_subsys_init(void);
 518
 519 /* Flags for xfrm_lookup flags argument. */
 520 enum {
 521         XFRM_LOOKUP_ICMP = 1 << 0,
 522         XFRM_LOOKUP_QUEUE = 1 << 1,
 523         XFRM_LOOKUP_KEEP_DST_REF = 1 << 2,
 524 };
 525
 526 struct flowi;
 527 #ifndef CONFIG_XFRM
 528 static inline struct dst_entry *xfrm_lookup(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 dst_entry *xfrm_lookup_route(struct net *net,
 538                                                   struct dst_entry *dst_orig,
 539                                                   const struct flowi *fl,
 540                                                   const struct sock *sk,
 541                                                   int flags)
 542 {
 543         return dst_orig;
 544 }
 545
 546 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
 547 {
 548         return NULL;
 549 }
 550
 551 #else
 552 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
 553                               const struct flowi *fl, const struct sock *sk,
 554                               int flags);
 555
 556 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
 557                                     const struct flowi *fl, const struct sock *sk,
 558                                     int flags);
 559
 560 /* skb attached with this dst needs transformation if dst->xfrm is valid */
 561 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
 562 {
 563         return dst->xfrm;
 564 }
 565 #endif
 566
 567 #endif /* _NET_DST_H */