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