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 sk_buff *);
  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_NOPEER              0x0040
  58 #define DST_FAKE_RTABLE         0x0080
  59 #define DST_XFRM_TUNNEL         0x0100
  60 #define DST_XFRM_QUEUE          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         /*
  88          * Align __refcnt to a 64 bytes alignment
  89          * (L1_CACHE_SIZE would be too much)
  90          */
  91 #ifdef CONFIG_64BIT
  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         union {
 102                 struct dst_entry        *next;
 103                 struct rtable __rcu     *rt_next;
 104                 struct rt6_info         *rt6_next;
 105                 struct dn_route __rcu   *dn_next;
 106         };
 107 };
 108
 109 extern u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
 110 extern const u32 dst_default_metrics[];
 111
 112 #define DST_METRICS_READ_ONLY   0x1UL
 113 #define __DST_METRICS_PTR(Y)    \
 114         ((u32 *)((Y) & ~DST_METRICS_READ_ONLY))
 115 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
 116
 117 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
 118 {
 119         return dst->_metrics & DST_METRICS_READ_ONLY;
 120 }
 121
 122 extern void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
 123
 124 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
 125 {
 126         unsigned long val = dst->_metrics;
 127         if (!(val & DST_METRICS_READ_ONLY))
 128                 __dst_destroy_metrics_generic(dst, val);
 129 }
 130
 131 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
 132 {
 133         unsigned long p = dst->_metrics;
 134
 135         BUG_ON(!p);
 136
 137         if (p & DST_METRICS_READ_ONLY)
 138                 return dst->ops->cow_metrics(dst, p);
 139         return __DST_METRICS_PTR(p);
 140 }
 141
 142 /* This may only be invoked before the entry has reached global
 143  * visibility.
 144  */
 145 static inline void dst_init_metrics(struct dst_entry *dst,
 146                                     const u32 *src_metrics,
 147                                     bool read_only)
 148 {
 149         dst->_metrics = ((unsigned long) src_metrics) |
 150                 (read_only ? DST_METRICS_READ_ONLY : 0);
 151 }
 152
 153 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
 154 {
 155         u32 *dst_metrics = dst_metrics_write_ptr(dest);
 156
 157         if (dst_metrics) {
 158                 u32 *src_metrics = DST_METRICS_PTR(src);
 159
 160                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
 161         }
 162 }
 163
 164 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
 165 {
 166         return DST_METRICS_PTR(dst);
 167 }
 168
 169 static inline u32
 170 dst_metric_raw(const struct dst_entry *dst, const int metric)
 171 {
 172         u32 *p = DST_METRICS_PTR(dst);
 173
 174         return p[metric-1];
 175 }
 176
 177 static inline u32
 178 dst_metric(const struct dst_entry *dst, const int metric)
 179 {
 180         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
 181                      metric == RTAX_ADVMSS ||
 182                      metric == RTAX_MTU);
 183         return dst_metric_raw(dst, metric);
 184 }
 185
 186 static inline u32
 187 dst_metric_advmss(const struct dst_entry *dst)
 188 {
 189         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
 190
 191         if (!advmss)
 192                 advmss = dst->ops->default_advmss(dst);
 193
 194         return advmss;
 195 }
 196
 197 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
 198 {
 199         u32 *p = dst_metrics_write_ptr(dst);
 200
 201         if (p)
 202                 p[metric-1] = val;
 203 }
 204
 205 static inline u32
 206 dst_feature(const struct dst_entry *dst, u32 feature)
 207 {
 208         return dst_metric(dst, RTAX_FEATURES) & feature;
 209 }
 210
 211 static inline u32 dst_mtu(const struct dst_entry *dst)
 212 {
 213         return dst->ops->mtu(dst);
 214 }
 215
 216 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 217 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 218 {
 219         return msecs_to_jiffies(dst_metric(dst, metric));
 220 }
 221
 222 static inline u32
 223 dst_allfrag(const struct dst_entry *dst)
 224 {
 225         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
 226         return ret;
 227 }
 228
 229 static inline int
 230 dst_metric_locked(const struct dst_entry *dst, int metric)
 231 {
 232         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 233 }
 234
 235 static inline void dst_hold(struct dst_entry *dst)
 236 {
 237         /*
 238          * If your kernel compilation stops here, please check
 239          * __pad_to_align_refcnt declaration in struct dst_entry
 240          */
 241         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 242         atomic_inc(&dst->__refcnt);
 243 }
 244
 245 static inline void dst_use(struct dst_entry *dst, unsigned long time)
 246 {
 247         dst_hold(dst);
 248         dst->__use++;
 249         dst->lastuse = time;
 250 }
 251
 252 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
 253 {
 254         dst->__use++;
 255         dst->lastuse = time;
 256 }
 257
 258 static inline struct dst_entry *dst_clone(struct dst_entry *dst)
 259 {
 260         if (dst)
 261                 atomic_inc(&dst->__refcnt);
 262         return dst;
 263 }
 264
 265 extern void dst_release(struct dst_entry *dst);
 266
 267 static inline void refdst_drop(unsigned long refdst)
 268 {
 269         if (!(refdst & SKB_DST_NOREF))
 270                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 271 }
 272
 273 /**
 274  * skb_dst_drop - drops skb dst
 275  * @skb: buffer
 276  *
 277  * Drops dst reference count if a reference was taken.
 278  */
 279 static inline void skb_dst_drop(struct sk_buff *skb)
 280 {
 281         if (skb->_skb_refdst) {
 282                 refdst_drop(skb->_skb_refdst);
 283                 skb->_skb_refdst = 0UL;
 284         }
 285 }
 286
 287 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 288 {
 289         nskb->_skb_refdst = oskb->_skb_refdst;
 290         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 291                 dst_clone(skb_dst(nskb));
 292 }
 293
 294 /**
 295  * skb_dst_force - makes sure skb dst is refcounted
 296  * @skb: buffer
 297  *
 298  * If dst is not yet refcounted, let's do it
 299  */
 300 static inline void skb_dst_force(struct sk_buff *skb)
 301 {
 302         if (skb_dst_is_noref(skb)) {
 303                 WARN_ON(!rcu_read_lock_held());
 304                 skb->_skb_refdst &= ~SKB_DST_NOREF;
 305                 dst_clone(skb_dst(skb));
 306         }
 307 }
 308
 309 /**
 310  * dst_hold_safe - Take a reference on a dst if possible
 311  * @dst: pointer to dst entry
 312  *
 313  * This helper returns false if it could not safely
 314  * take a reference on a dst.
 315  */
 316 static inline bool dst_hold_safe(struct dst_entry *dst)
 317 {
 318         if (dst->flags & DST_NOCACHE)
 319                 return atomic_inc_not_zero(&dst->__refcnt);
 320         dst_hold(dst);
 321         return true;
 322 }
 323
 324 /**
 325  * skb_dst_force_safe - makes sure skb dst is refcounted
 326  * @skb: buffer
 327  *
 328  * If dst is not yet refcounted and not destroyed, grab a ref on it.
 329  */
 330 static inline void skb_dst_force_safe(struct sk_buff *skb)
 331 {
 332         if (skb_dst_is_noref(skb)) {
 333                 struct dst_entry *dst = skb_dst(skb);
 334
 335                 if (!dst_hold_safe(dst))
 336                         dst = NULL;
 337
 338                 skb->_skb_refdst = (unsigned long)dst;
 339         }
 340 }
 341
 342
 343 /**
 344  *      __skb_tunnel_rx - prepare skb for rx reinsert
 345  *      @skb: buffer
 346  *      @dev: tunnel device
 347  *      @net: netns for packet i/o
 348  *
 349  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 350  *      so make some cleanups. (no accounting done)
 351  */
 352 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 353                                    struct net *net)
 354 {
 355         skb->dev = dev;
 356
 357         /*
 358          * Clear rxhash so that we can recalulate the hash for the
 359          * encapsulated packet, unless we have already determine the hash
 360          * over the L4 4-tuple.
 361          */
 362         if (!skb->l4_rxhash)
 363                 skb->rxhash = 0;
 364         skb_set_queue_mapping(skb, 0);
 365         skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
 366 }
 367
 368 /**
 369  *      skb_tunnel_rx - prepare skb for rx reinsert
 370  *      @skb: buffer
 371  *      @dev: tunnel device
 372  *
 373  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 374  *      so make some cleanups, and perform accounting.
 375  *      Note: this accounting is not SMP safe.
 376  */
 377 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 378                                  struct net *net)
 379 {
 380         /* TODO : stats should be SMP safe */
 381         dev->stats.rx_packets++;
 382         dev->stats.rx_bytes += skb->len;
 383         __skb_tunnel_rx(skb, dev, net);
 384 }
 385
 386 /* Children define the path of the packet through the
 387  * Linux networking.  Thus, destinations are stackable.
 388  */
 389
 390 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb)
 391 {
 392         struct dst_entry *child = dst_clone(skb_dst(skb)->child);
 393
 394         skb_dst_drop(skb);
 395         return child;
 396 }
 397
 398 extern int dst_discard(struct sk_buff *skb);
 399 extern void *dst_alloc(struct dst_ops *ops, struct net_device *dev,
 400                        int initial_ref, int initial_obsolete,
 401                        unsigned short flags);
 402 extern void __dst_free(struct dst_entry *dst);
 403 extern struct dst_entry *dst_destroy(struct dst_entry *dst);
 404
 405 static inline void dst_free(struct dst_entry *dst)
 406 {
 407         if (dst->obsolete > 0)
 408                 return;
 409         if (!atomic_read(&dst->__refcnt)) {
 410                 dst = dst_destroy(dst);
 411                 if (!dst)
 412                         return;
 413         }
 414         __dst_free(dst);
 415 }
 416
 417 static inline void dst_rcu_free(struct rcu_head *head)
 418 {
 419         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 420         dst_free(dst);
 421 }
 422
 423 static inline void dst_confirm(struct dst_entry *dst)
 424 {
 425         dst->pending_confirm = 1;
 426 }
 427
 428 static inline int dst_neigh_output(struct dst_entry *dst, struct neighbour *n,
 429                                    struct sk_buff *skb)
 430 {
 431         const struct hh_cache *hh;
 432
 433         if (dst->pending_confirm) {
 434                 unsigned long now = jiffies;
 435
 436                 dst->pending_confirm = 0;
 437                 /* avoid dirtying neighbour */
 438                 if (n->confirmed != now)
 439                         n->confirmed = now;
 440         }
 441
 442         hh = &n->hh;
 443         if ((n->nud_state & NUD_CONNECTED) && hh->hh_len)
 444                 return neigh_hh_output(hh, skb);
 445         else
 446                 return n->output(n, skb);
 447 }
 448
 449 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
 450 {
 451         struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
 452         return IS_ERR(n) ? NULL : n;
 453 }
 454
 455 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
 456                                                      struct sk_buff *skb)
 457 {
 458         struct neighbour *n =  dst->ops->neigh_lookup(dst, skb, NULL);
 459         return IS_ERR(n) ? NULL : n;
 460 }
 461
 462 static inline void dst_link_failure(struct sk_buff *skb)
 463 {
 464         struct dst_entry *dst = skb_dst(skb);
 465         if (dst && dst->ops && dst->ops->link_failure)
 466                 dst->ops->link_failure(skb);
 467 }
 468
 469 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 470 {
 471         unsigned long expires = jiffies + timeout;
 472
 473         if (expires == 0)
 474                 expires = 1;
 475
 476         if (dst->expires == 0 || time_before(expires, dst->expires))
 477                 dst->expires = expires;
 478 }
 479
 480 /* Output packet to network from transport.  */
 481 static inline int dst_output(struct sk_buff *skb)
 482 {
 483         return skb_dst(skb)->output(skb);
 484 }
 485
 486 /* Input packet from network to transport.  */
 487 static inline int dst_input(struct sk_buff *skb)
 488 {
 489         return skb_dst(skb)->input(skb);
 490 }
 491
 492 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 493 {
 494         if (dst->obsolete)
 495                 dst = dst->ops->check(dst, cookie);
 496         return dst;
 497 }
 498
 499 extern void             dst_init(void);
 500
 501 /* Flags for xfrm_lookup flags argument. */
 502 enum {
 503         XFRM_LOOKUP_ICMP = 1 << 0,
 504         XFRM_LOOKUP_QUEUE = 1 << 1,
 505         XFRM_LOOKUP_KEEP_DST_REF = 1 << 2,
 506 };
 507
 508 struct flowi;
 509 #ifndef CONFIG_XFRM
 510 static inline struct dst_entry *xfrm_lookup(struct net *net,
 511                                             struct dst_entry *dst_orig,
 512                                             const struct flowi *fl, struct sock *sk,
 513                                             int flags)
 514 {
 515         return dst_orig;
 516 }
 517
 518 static inline struct dst_entry *xfrm_lookup_route(struct net *net,
 519                                                   struct dst_entry *dst_orig,
 520                                                   const struct flowi *fl,
 521                                                   struct sock *sk,
 522                                                   int flags)
 523 {
 524         return dst_orig;
 525 }
 526
 527 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
 528 {
 529         return NULL;
 530 }
 531
 532 #else
 533 extern struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
 534                                      const struct flowi *fl, struct sock *sk,
 535                                      int flags);
 536
 537 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
 538                                     const struct flowi *fl, struct sock *sk,
 539                                     int flags);
 540
 541 /* skb attached with this dst needs transformation if dst->xfrm is valid */
 542 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
 543 {
 544         return dst->xfrm;
 545 }
 546 #endif
 547
 548 #endif /* _NET_DST_H */