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         struct lwtunnel_state   *lwtstate;
  89         /*
  90          * Align __refcnt to a 64 bytes alignment
  91          * (L1_CACHE_SIZE would be too much)
  92          */
  93         long                    __pad_to_align_refcnt[1];
  94 #endif
  95         /*
  96          * __refcnt wants to be on a different cache line from
  97          * input/output/ops or performance tanks badly
  98          */
  99         atomic_t                __refcnt;       /* client references    */
 100         int                     __use;
 101         unsigned long           lastuse;
 102 #ifndef CONFIG_64BIT
 103         struct lwtunnel_state   *lwtstate;
 104 #endif
 105         union {
 106                 struct dst_entry        *next;
 107                 struct rtable __rcu     *rt_next;
 108                 struct rt6_info         *rt6_next;
 109                 struct dn_route __rcu   *dn_next;
 110         };
 111 };
 112
 113 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
 114 extern const u32 dst_default_metrics[];
 115
 116 #define DST_METRICS_READ_ONLY           0x1UL
 117 #define DST_METRICS_FLAGS               0x3UL
 118 #define __DST_METRICS_PTR(Y)    \
 119         ((u32 *)((Y) & ~DST_METRICS_FLAGS))
 120 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
 121
 122 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
 123 {
 124         return dst->_metrics & DST_METRICS_READ_ONLY;
 125 }
 126
 127 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
 128
 129 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
 130 {
 131         unsigned long val = dst->_metrics;
 132         if (!(val & DST_METRICS_READ_ONLY))
 133                 __dst_destroy_metrics_generic(dst, val);
 134 }
 135
 136 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
 137 {
 138         unsigned long p = dst->_metrics;
 139
 140         BUG_ON(!p);
 141
 142         if (p & DST_METRICS_READ_ONLY)
 143                 return dst->ops->cow_metrics(dst, p);
 144         return __DST_METRICS_PTR(p);
 145 }
 146
 147 /* This may only be invoked before the entry has reached global
 148  * visibility.
 149  */
 150 static inline void dst_init_metrics(struct dst_entry *dst,
 151                                     const u32 *src_metrics,
 152                                     bool read_only)
 153 {
 154         dst->_metrics = ((unsigned long) src_metrics) |
 155                 (read_only ? DST_METRICS_READ_ONLY : 0);
 156 }
 157
 158 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
 159 {
 160         u32 *dst_metrics = dst_metrics_write_ptr(dest);
 161
 162         if (dst_metrics) {
 163                 u32 *src_metrics = DST_METRICS_PTR(src);
 164
 165                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
 166         }
 167 }
 168
 169 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
 170 {
 171         return DST_METRICS_PTR(dst);
 172 }
 173
 174 static inline u32
 175 dst_metric_raw(const struct dst_entry *dst, const int metric)
 176 {
 177         u32 *p = DST_METRICS_PTR(dst);
 178
 179         return p[metric-1];
 180 }
 181
 182 static inline u32
 183 dst_metric(const struct dst_entry *dst, const int metric)
 184 {
 185         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
 186                      metric == RTAX_ADVMSS ||
 187                      metric == RTAX_MTU);
 188         return dst_metric_raw(dst, metric);
 189 }
 190
 191 static inline u32
 192 dst_metric_advmss(const struct dst_entry *dst)
 193 {
 194         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
 195
 196         if (!advmss)
 197                 advmss = dst->ops->default_advmss(dst);
 198
 199         return advmss;
 200 }
 201
 202 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
 203 {
 204         u32 *p = dst_metrics_write_ptr(dst);
 205
 206         if (p)
 207                 p[metric-1] = val;
 208 }
 209
 210 /* Kernel-internal feature bits that are unallocated in user space. */
 211 #define DST_FEATURE_ECN_CA      (1 << 31)
 212
 213 #define DST_FEATURE_MASK        (DST_FEATURE_ECN_CA)
 214 #define DST_FEATURE_ECN_MASK    (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN)
 215
 216 static inline u32
 217 dst_feature(const struct dst_entry *dst, u32 feature)
 218 {
 219         return dst_metric(dst, RTAX_FEATURES) & feature;
 220 }
 221
 222 static inline u32 dst_mtu(const struct dst_entry *dst)
 223 {
 224         return dst->ops->mtu(dst);
 225 }
 226
 227 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 228 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 229 {
 230         return msecs_to_jiffies(dst_metric(dst, metric));
 231 }
 232
 233 static inline u32
 234 dst_allfrag(const struct dst_entry *dst)
 235 {
 236         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
 237         return ret;
 238 }
 239
 240 static inline int
 241 dst_metric_locked(const struct dst_entry *dst, int metric)
 242 {
 243         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 244 }
 245
 246 static inline void dst_hold(struct dst_entry *dst)
 247 {
 248         /*
 249          * If your kernel compilation stops here, please check
 250          * __pad_to_align_refcnt declaration in struct dst_entry
 251          */
 252         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 253         atomic_inc(&dst->__refcnt);
 254 }
 255
 256 static inline void dst_use(struct dst_entry *dst, unsigned long time)
 257 {
 258         dst_hold(dst);
 259         dst->__use++;
 260         dst->lastuse = time;
 261 }
 262
 263 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
 264 {
 265         dst->__use++;
 266         dst->lastuse = time;
 267 }
 268
 269 static inline struct dst_entry *dst_clone(struct dst_entry *dst)
 270 {
 271         if (dst)
 272                 atomic_inc(&dst->__refcnt);
 273         return dst;
 274 }
 275
 276 void dst_release(struct dst_entry *dst);
 277
 278 static inline void refdst_drop(unsigned long refdst)
 279 {
 280         if (!(refdst & SKB_DST_NOREF))
 281                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 282 }
 283
 284 /**
 285  * skb_dst_drop - drops skb dst
 286  * @skb: buffer
 287  *
 288  * Drops dst reference count if a reference was taken.
 289  */
 290 static inline void skb_dst_drop(struct sk_buff *skb)
 291 {
 292         if (skb->_skb_refdst) {
 293                 refdst_drop(skb->_skb_refdst);
 294                 skb->_skb_refdst = 0UL;
 295         }
 296 }
 297
 298 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst)
 299 {
 300         nskb->_skb_refdst = refdst;
 301         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 302                 dst_clone(skb_dst(nskb));
 303 }
 304
 305 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 306 {
 307         __skb_dst_copy(nskb, oskb->_skb_refdst);
 308 }
 309
 310 /**
 311  * skb_dst_force - makes sure skb dst is refcounted
 312  * @skb: buffer
 313  *
 314  * If dst is not yet refcounted, let's do it
 315  */
 316 static inline void skb_dst_force(struct sk_buff *skb)
 317 {
 318         if (skb_dst_is_noref(skb)) {
 319                 WARN_ON(!rcu_read_lock_held());
 320                 skb->_skb_refdst &= ~SKB_DST_NOREF;
 321                 dst_clone(skb_dst(skb));
 322         }
 323 }
 324
 325 /**
 326  * dst_hold_safe - Take a reference on a dst if possible
 327  * @dst: pointer to dst entry
 328  *
 329  * This helper returns false if it could not safely
 330  * take a reference on a dst.
 331  */
 332 static inline bool dst_hold_safe(struct dst_entry *dst)
 333 {
 334         if (dst->flags & DST_NOCACHE)
 335                 return atomic_inc_not_zero(&dst->__refcnt);
 336         dst_hold(dst);
 337         return true;
 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 void __dst_free(struct dst_entry *dst);
 424 struct dst_entry *dst_destroy(struct dst_entry *dst);
 425
 426 static inline void dst_free(struct dst_entry *dst)
 427 {
 428         if (dst->obsolete > 0)
 429                 return;
 430         if (!atomic_read(&dst->__refcnt)) {
 431                 dst = dst_destroy(dst);
 432                 if (!dst)
 433                         return;
 434         }
 435         __dst_free(dst);
 436 }
 437
 438 static inline void dst_rcu_free(struct rcu_head *head)
 439 {
 440         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 441         dst_free(dst);
 442 }
 443
 444 static inline void dst_confirm(struct dst_entry *dst)
 445 {
 446         dst->pending_confirm = 1;
 447 }
 448
 449 static inline int dst_neigh_output(struct dst_entry *dst, struct neighbour *n,
 450                                    struct sk_buff *skb)
 451 {
 452         const struct hh_cache *hh;
 453
 454         if (dst->pending_confirm) {
 455                 unsigned long now = jiffies;
 456
 457                 dst->pending_confirm = 0;
 458                 /* avoid dirtying neighbour */
 459                 if (n->confirmed != now)
 460                         n->confirmed = now;
 461         }
 462
 463         hh = &n->hh;
 464         if ((n->nud_state & NUD_CONNECTED) && hh->hh_len)
 465                 return neigh_hh_output(hh, skb);
 466         else
 467                 return n->output(n, skb);
 468 }
 469
 470 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
 471 {
 472         struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
 473         return IS_ERR(n) ? NULL : n;
 474 }
 475
 476 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
 477                                                      struct sk_buff *skb)
 478 {
 479         struct neighbour *n =  dst->ops->neigh_lookup(dst, skb, NULL);
 480         return IS_ERR(n) ? NULL : n;
 481 }
 482
 483 static inline void dst_link_failure(struct sk_buff *skb)
 484 {
 485         struct dst_entry *dst = skb_dst(skb);
 486         if (dst && dst->ops && dst->ops->link_failure)
 487                 dst->ops->link_failure(skb);
 488 }
 489
 490 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 491 {
 492         unsigned long expires = jiffies + timeout;
 493
 494         if (expires == 0)
 495                 expires = 1;
 496
 497         if (dst->expires == 0 || time_before(expires, dst->expires))
 498                 dst->expires = expires;
 499 }
 500
 501 /* Output packet to network from transport.  */
 502 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 503 {
 504         return skb_dst(skb)->output(net, sk, skb);
 505 }
 506
 507 /* Input packet from network to transport.  */
 508 static inline int dst_input(struct sk_buff *skb)
 509 {
 510         return skb_dst(skb)->input(skb);
 511 }
 512
 513 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 514 {
 515         if (dst->obsolete)
 516                 dst = dst->ops->check(dst, cookie);
 517         return dst;
 518 }
 519
 520 void dst_subsys_init(void);
 521
 522 /* Flags for xfrm_lookup flags argument. */
 523 enum {
 524         XFRM_LOOKUP_ICMP = 1 << 0,
 525         XFRM_LOOKUP_QUEUE = 1 << 1,
 526         XFRM_LOOKUP_KEEP_DST_REF = 1 << 2,
 527 };
 528
 529 struct flowi;
 530 #ifndef CONFIG_XFRM
 531 static inline struct dst_entry *xfrm_lookup(struct net *net,
 532                                             struct dst_entry *dst_orig,
 533                                             const struct flowi *fl,
 534                                             const struct sock *sk,
 535                                             int flags)
 536 {
 537         return dst_orig;
 538 }
 539
 540 static inline struct dst_entry *xfrm_lookup_route(struct net *net,
 541                                                   struct dst_entry *dst_orig,
 542                                                   const struct flowi *fl,
 543                                                   const struct sock *sk,
 544                                                   int flags)
 545 {
 546         return dst_orig;
 547 }
 548
 549 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
 550 {
 551         return NULL;
 552 }
 553
 554 #else
 555 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
 556                               const struct flowi *fl, const struct sock *sk,
 557                               int flags);
 558
 559 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
 560                                     const struct flowi *fl, const struct sock *sk,
 561                                     int flags);
 562
 563 /* skb attached with this dst needs transformation if dst->xfrm is valid */
 564 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
 565 {
 566         return dst->xfrm;
 567 }
 568 #endif
 569
 570 #endif /* _NET_DST_H */