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 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
  61         unsigned short          pending_confirm;
  62
  63         short                   error;
  64
  65         /* A non-zero value of dst->obsolete forces by-hand validation
  66          * of the route entry.  Positive values are set by the generic
  67          * dst layer to indicate that the entry has been forcefully
  68          * destroyed.
  69          *
  70          * Negative values are used by the implementation layer code to
  71          * force invocation of the dst_ops->check() method.
  72          */
  73         short                   obsolete;
  74 #define DST_OBSOLETE_NONE       0
  75 #define DST_OBSOLETE_DEAD       2
  76 #define DST_OBSOLETE_FORCE_CHK  -1
  77 #define DST_OBSOLETE_KILL       -2
  78         unsigned short          header_len;     /* more space at head required */
  79         unsigned short          trailer_len;    /* space to reserve at tail */
  80 #ifdef CONFIG_IP_ROUTE_CLASSID
  81         __u32                   tclassid;
  82 #else
  83         __u32                   __pad2;
  84 #endif
  85
  86         /*
  87          * Align __refcnt to a 64 bytes alignment
  88          * (L1_CACHE_SIZE would be too much)
  89          */
  90 #ifdef CONFIG_64BIT
  91         long                    __pad_to_align_refcnt[2];
  92 #endif
  93         /*
  94          * __refcnt wants to be on a different cache line from
  95          * input/output/ops or performance tanks badly
  96          */
  97         atomic_t                __refcnt;       /* client references    */
  98         int                     __use;
  99         unsigned long           lastuse;
 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 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
 109 extern const u32 dst_default_metrics[];
 110
 111 #define DST_METRICS_READ_ONLY           0x1UL
 112 #define DST_METRICS_FORCE_OVERWRITE     0x2UL
 113 #define DST_METRICS_FLAGS               0x3UL
 114 #define __DST_METRICS_PTR(Y)    \
 115         ((u32 *)((Y) & ~DST_METRICS_FLAGS))
 116 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
 117
 118 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
 119 {
 120         return dst->_metrics & DST_METRICS_READ_ONLY;
 121 }
 122
 123 static inline void dst_metrics_set_force_overwrite(struct dst_entry *dst)
 124 {
 125         dst->_metrics |= DST_METRICS_FORCE_OVERWRITE;
 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 static inline u32
 212 dst_feature(const struct dst_entry *dst, u32 feature)
 213 {
 214         return dst_metric(dst, RTAX_FEATURES) & feature;
 215 }
 216
 217 static inline u32 dst_mtu(const struct dst_entry *dst)
 218 {
 219         return dst->ops->mtu(dst);
 220 }
 221
 222 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 223 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 224 {
 225         return msecs_to_jiffies(dst_metric(dst, metric));
 226 }
 227
 228 static inline u32
 229 dst_allfrag(const struct dst_entry *dst)
 230 {
 231         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
 232         return ret;
 233 }
 234
 235 static inline int
 236 dst_metric_locked(const struct dst_entry *dst, int metric)
 237 {
 238         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 239 }
 240
 241 static inline void dst_hold(struct dst_entry *dst)
 242 {
 243         /*
 244          * If your kernel compilation stops here, please check
 245          * __pad_to_align_refcnt declaration in struct dst_entry
 246          */
 247         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 248         atomic_inc(&dst->__refcnt);
 249 }
 250
 251 static inline void dst_use(struct dst_entry *dst, unsigned long time)
 252 {
 253         dst_hold(dst);
 254         dst->__use++;
 255         dst->lastuse = time;
 256 }
 257
 258 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
 259 {
 260         dst->__use++;
 261         dst->lastuse = time;
 262 }
 263
 264 static inline struct dst_entry *dst_clone(struct dst_entry *dst)
 265 {
 266         if (dst)
 267                 atomic_inc(&dst->__refcnt);
 268         return dst;
 269 }
 270
 271 void dst_release(struct dst_entry *dst);
 272
 273 static inline void refdst_drop(unsigned long refdst)
 274 {
 275         if (!(refdst & SKB_DST_NOREF))
 276                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 277 }
 278
 279 /**
 280  * skb_dst_drop - drops skb dst
 281  * @skb: buffer
 282  *
 283  * Drops dst reference count if a reference was taken.
 284  */
 285 static inline void skb_dst_drop(struct sk_buff *skb)
 286 {
 287         if (skb->_skb_refdst) {
 288                 refdst_drop(skb->_skb_refdst);
 289                 skb->_skb_refdst = 0UL;
 290         }
 291 }
 292
 293 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 294 {
 295         nskb->_skb_refdst = oskb->_skb_refdst;
 296         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 297                 dst_clone(skb_dst(nskb));
 298 }
 299
 300 /**
 301  * skb_dst_force - makes sure skb dst is refcounted
 302  * @skb: buffer
 303  *
 304  * If dst is not yet refcounted, let's do it
 305  */
 306 static inline void skb_dst_force(struct sk_buff *skb)
 307 {
 308         if (skb_dst_is_noref(skb)) {
 309                 WARN_ON(!rcu_read_lock_held());
 310                 skb->_skb_refdst &= ~SKB_DST_NOREF;
 311                 dst_clone(skb_dst(skb));
 312         }
 313 }
 314
 315
 316 /**
 317  *      __skb_tunnel_rx - prepare skb for rx reinsert
 318  *      @skb: buffer
 319  *      @dev: tunnel device
 320  *      @net: netns for packet i/o
 321  *
 322  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 323  *      so make some cleanups. (no accounting done)
 324  */
 325 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 326                                    struct net *net)
 327 {
 328         skb->dev = dev;
 329
 330         /*
 331          * Clear hash so that we can recalulate the hash for the
 332          * encapsulated packet, unless we have already determine the hash
 333          * over the L4 4-tuple.
 334          */
 335         skb_clear_hash_if_not_l4(skb);
 336         skb_set_queue_mapping(skb, 0);
 337         skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
 338 }
 339
 340 /**
 341  *      skb_tunnel_rx - prepare skb for rx reinsert
 342  *      @skb: buffer
 343  *      @dev: tunnel device
 344  *
 345  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 346  *      so make some cleanups, and perform accounting.
 347  *      Note: this accounting is not SMP safe.
 348  */
 349 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 350                                  struct net *net)
 351 {
 352         /* TODO : stats should be SMP safe */
 353         dev->stats.rx_packets++;
 354         dev->stats.rx_bytes += skb->len;
 355         __skb_tunnel_rx(skb, dev, net);
 356 }
 357
 358 /* Children define the path of the packet through the
 359  * Linux networking.  Thus, destinations are stackable.
 360  */
 361
 362 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb)
 363 {
 364         struct dst_entry *child = dst_clone(skb_dst(skb)->child);
 365
 366         skb_dst_drop(skb);
 367         return child;
 368 }
 369
 370 int dst_discard_sk(struct sock *sk, struct sk_buff *skb);
 371 static inline int dst_discard(struct sk_buff *skb)
 372 {
 373         return dst_discard_sk(skb->sk, skb);
 374 }
 375 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref,
 376                 int initial_obsolete, unsigned short flags);
 377 void __dst_free(struct dst_entry *dst);
 378 struct dst_entry *dst_destroy(struct dst_entry *dst);
 379
 380 static inline void dst_free(struct dst_entry *dst)
 381 {
 382         if (dst->obsolete > 0)
 383                 return;
 384         if (!atomic_read(&dst->__refcnt)) {
 385                 dst = dst_destroy(dst);
 386                 if (!dst)
 387                         return;
 388         }
 389         __dst_free(dst);
 390 }
 391
 392 static inline void dst_rcu_free(struct rcu_head *head)
 393 {
 394         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 395         dst_free(dst);
 396 }
 397
 398 static inline void dst_confirm(struct dst_entry *dst)
 399 {
 400         dst->pending_confirm = 1;
 401 }
 402
 403 static inline int dst_neigh_output(struct dst_entry *dst, struct neighbour *n,
 404                                    struct sk_buff *skb)
 405 {
 406         const struct hh_cache *hh;
 407
 408         if (dst->pending_confirm) {
 409                 unsigned long now = jiffies;
 410
 411                 dst->pending_confirm = 0;
 412                 /* avoid dirtying neighbour */
 413                 if (n->confirmed != now)
 414                         n->confirmed = now;
 415         }
 416
 417         hh = &n->hh;
 418         if ((n->nud_state & NUD_CONNECTED) && hh->hh_len)
 419                 return neigh_hh_output(hh, skb);
 420         else
 421                 return n->output(n, skb);
 422 }
 423
 424 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
 425 {
 426         struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
 427         return IS_ERR(n) ? NULL : n;
 428 }
 429
 430 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
 431                                                      struct sk_buff *skb)
 432 {
 433         struct neighbour *n =  dst->ops->neigh_lookup(dst, skb, NULL);
 434         return IS_ERR(n) ? NULL : n;
 435 }
 436
 437 static inline void dst_link_failure(struct sk_buff *skb)
 438 {
 439         struct dst_entry *dst = skb_dst(skb);
 440         if (dst && dst->ops && dst->ops->link_failure)
 441                 dst->ops->link_failure(skb);
 442 }
 443
 444 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 445 {
 446         unsigned long expires = jiffies + timeout;
 447
 448         if (expires == 0)
 449                 expires = 1;
 450
 451         if (dst->expires == 0 || time_before(expires, dst->expires))
 452                 dst->expires = expires;
 453 }
 454
 455 /* Output packet to network from transport.  */
 456 static inline int dst_output_sk(struct sock *sk, struct sk_buff *skb)
 457 {
 458         return skb_dst(skb)->output(sk, skb);
 459 }
 460 static inline int dst_output(struct sk_buff *skb)
 461 {
 462         return dst_output_sk(skb->sk, skb);
 463 }
 464
 465 /* Input packet from network to transport.  */
 466 static inline int dst_input(struct sk_buff *skb)
 467 {
 468         return skb_dst(skb)->input(skb);
 469 }
 470
 471 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 472 {
 473         if (dst->obsolete)
 474                 dst = dst->ops->check(dst, cookie);
 475         return dst;
 476 }
 477
 478 void dst_init(void);
 479
 480 /* Flags for xfrm_lookup flags argument. */
 481 enum {
 482         XFRM_LOOKUP_ICMP = 1 << 0,
 483         XFRM_LOOKUP_QUEUE = 1 << 1,
 484         XFRM_LOOKUP_KEEP_DST_REF = 1 << 2,
 485 };
 486
 487 struct flowi;
 488 #ifndef CONFIG_XFRM
 489 static inline struct dst_entry *xfrm_lookup(struct net *net,
 490                                             struct dst_entry *dst_orig,
 491                                             const struct flowi *fl, struct sock *sk,
 492                                             int flags)
 493 {
 494         return dst_orig;
 495 }
 496
 497 static inline struct dst_entry *xfrm_lookup_route(struct net *net,
 498                                                   struct dst_entry *dst_orig,
 499                                                   const struct flowi *fl,
 500                                                   struct sock *sk,
 501                                                   int flags)
 502 {
 503         return dst_orig;
 504 }
 505
 506 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
 507 {
 508         return NULL;
 509 }
 510
 511 #else
 512 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
 513                               const struct flowi *fl, struct sock *sk,
 514                               int flags);
 515
 516 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
 517                                     const struct flowi *fl, struct sock *sk,
 518                                     int flags);
 519
 520 /* skb attached with this dst needs transformation if dst->xfrm is valid */
 521 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
 522 {
 523         return dst->xfrm;
 524 }
 525 #endif
 526
 527 #endif /* _NET_DST_H */