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         short                   error;
  63
  64         /* A non-zero value of dst->obsolete forces by-hand validation
  65          * of the route entry.  Positive values are set by the generic
  66          * dst layer to indicate that the entry has been forcefully
  67          * destroyed.
  68          *
  69          * Negative values are used by the implementation layer code to
  70          * force invocation of the dst_ops->check() method.
  71          */
  72         short                   obsolete;
  73 #define DST_OBSOLETE_NONE       0
  74 #define DST_OBSOLETE_DEAD       2
  75 #define DST_OBSOLETE_FORCE_CHK  -1
  76 #define DST_OBSOLETE_KILL       -2
  77         unsigned short          header_len;     /* more space at head required */
  78         unsigned short          trailer_len;    /* space to reserve at tail */
  79         unsigned short          __pad3;
  80
  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 struct dst_metrics {
 111         u32             metrics[RTAX_MAX];
 112         atomic_t        refcnt;
 113 };
 114 extern const struct dst_metrics dst_default_metrics;
 115
 116 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
 117
 118 #define DST_METRICS_READ_ONLY           0x1UL
 119 #define DST_METRICS_REFCOUNTED          0x2UL
 120 #define DST_METRICS_FLAGS               0x3UL
 121 #define __DST_METRICS_PTR(Y)    \
 122         ((u32 *)((Y) & ~DST_METRICS_FLAGS))
 123 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
 124
 125 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
 126 {
 127         return dst->_metrics & DST_METRICS_READ_ONLY;
 128 }
 129
 130 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
 131
 132 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
 133 {
 134         unsigned long val = dst->_metrics;
 135         if (!(val & DST_METRICS_READ_ONLY))
 136                 __dst_destroy_metrics_generic(dst, val);
 137 }
 138
 139 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
 140 {
 141         unsigned long p = dst->_metrics;
 142
 143         BUG_ON(!p);
 144
 145         if (p & DST_METRICS_READ_ONLY)
 146                 return dst->ops->cow_metrics(dst, p);
 147         return __DST_METRICS_PTR(p);
 148 }
 149
 150 /* This may only be invoked before the entry has reached global
 151  * visibility.
 152  */
 153 static inline void dst_init_metrics(struct dst_entry *dst,
 154                                     const u32 *src_metrics,
 155                                     bool read_only)
 156 {
 157         dst->_metrics = ((unsigned long) src_metrics) |
 158                 (read_only ? DST_METRICS_READ_ONLY : 0);
 159 }
 160
 161 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
 162 {
 163         u32 *dst_metrics = dst_metrics_write_ptr(dest);
 164
 165         if (dst_metrics) {
 166                 u32 *src_metrics = DST_METRICS_PTR(src);
 167
 168                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
 169         }
 170 }
 171
 172 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
 173 {
 174         return DST_METRICS_PTR(dst);
 175 }
 176
 177 static inline u32
 178 dst_metric_raw(const struct dst_entry *dst, const int metric)
 179 {
 180         u32 *p = DST_METRICS_PTR(dst);
 181
 182         return p[metric-1];
 183 }
 184
 185 static inline u32
 186 dst_metric(const struct dst_entry *dst, const int metric)
 187 {
 188         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
 189                      metric == RTAX_ADVMSS ||
 190                      metric == RTAX_MTU);
 191         return dst_metric_raw(dst, metric);
 192 }
 193
 194 static inline u32
 195 dst_metric_advmss(const struct dst_entry *dst)
 196 {
 197         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
 198
 199         if (!advmss)
 200                 advmss = dst->ops->default_advmss(dst);
 201
 202         return advmss;
 203 }
 204
 205 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
 206 {
 207         u32 *p = dst_metrics_write_ptr(dst);
 208
 209         if (p)
 210                 p[metric-1] = val;
 211 }
 212
 213 /* Kernel-internal feature bits that are unallocated in user space. */
 214 #define DST_FEATURE_ECN_CA      (1 << 31)
 215
 216 #define DST_FEATURE_MASK        (DST_FEATURE_ECN_CA)
 217 #define DST_FEATURE_ECN_MASK    (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN)
 218
 219 static inline u32
 220 dst_feature(const struct dst_entry *dst, u32 feature)
 221 {
 222         return dst_metric(dst, RTAX_FEATURES) & feature;
 223 }
 224
 225 static inline u32 dst_mtu(const struct dst_entry *dst)
 226 {
 227         return dst->ops->mtu(dst);
 228 }
 229
 230 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 231 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 232 {
 233         return msecs_to_jiffies(dst_metric(dst, metric));
 234 }
 235
 236 static inline u32
 237 dst_allfrag(const struct dst_entry *dst)
 238 {
 239         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
 240         return ret;
 241 }
 242
 243 static inline int
 244 dst_metric_locked(const struct dst_entry *dst, int metric)
 245 {
 246         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 247 }
 248
 249 static inline void dst_hold(struct dst_entry *dst)
 250 {
 251         /*
 252          * If your kernel compilation stops here, please check
 253          * __pad_to_align_refcnt declaration in struct dst_entry
 254          */
 255         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 256         atomic_inc(&dst->__refcnt);
 257 }
 258
 259 static inline void dst_use(struct dst_entry *dst, unsigned long time)
 260 {
 261         dst_hold(dst);
 262         dst->__use++;
 263         dst->lastuse = time;
 264 }
 265
 266 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
 267 {
 268         dst->__use++;
 269         dst->lastuse = time;
 270 }
 271
 272 static inline struct dst_entry *dst_clone(struct dst_entry *dst)
 273 {
 274         if (dst)
 275                 atomic_inc(&dst->__refcnt);
 276         return dst;
 277 }
 278
 279 void dst_release(struct dst_entry *dst);
 280
 281 static inline void refdst_drop(unsigned long refdst)
 282 {
 283         if (!(refdst & SKB_DST_NOREF))
 284                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 285 }
 286
 287 /**
 288  * skb_dst_drop - drops skb dst
 289  * @skb: buffer
 290  *
 291  * Drops dst reference count if a reference was taken.
 292  */
 293 static inline void skb_dst_drop(struct sk_buff *skb)
 294 {
 295         if (skb->_skb_refdst) {
 296                 refdst_drop(skb->_skb_refdst);
 297                 skb->_skb_refdst = 0UL;
 298         }
 299 }
 300
 301 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst)
 302 {
 303         nskb->_skb_refdst = refdst;
 304         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 305                 dst_clone(skb_dst(nskb));
 306 }
 307
 308 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 309 {
 310         __skb_dst_copy(nskb, oskb->_skb_refdst);
 311 }
 312
 313 /**
 314  * skb_dst_force - makes sure skb dst is refcounted
 315  * @skb: buffer
 316  *
 317  * If dst is not yet refcounted, let's do it
 318  */
 319 static inline void skb_dst_force(struct sk_buff *skb)
 320 {
 321         if (skb_dst_is_noref(skb)) {
 322                 WARN_ON(!rcu_read_lock_held());
 323                 skb->_skb_refdst &= ~SKB_DST_NOREF;
 324                 dst_clone(skb_dst(skb));
 325         }
 326 }
 327
 328 /**
 329  * dst_hold_safe - Take a reference on a dst if possible
 330  * @dst: pointer to dst entry
 331  *
 332  * This helper returns false if it could not safely
 333  * take a reference on a dst.
 334  */
 335 static inline bool dst_hold_safe(struct dst_entry *dst)
 336 {
 337         if (dst->flags & DST_NOCACHE)
 338                 return atomic_inc_not_zero(&dst->__refcnt);
 339         dst_hold(dst);
 340         return true;
 341 }
 342
 343 /**
 344  * skb_dst_force_safe - makes sure skb dst is refcounted
 345  * @skb: buffer
 346  *
 347  * If dst is not yet refcounted and not destroyed, grab a ref on it.
 348  */
 349 static inline void skb_dst_force_safe(struct sk_buff *skb)
 350 {
 351         if (skb_dst_is_noref(skb)) {
 352                 struct dst_entry *dst = skb_dst(skb);
 353
 354                 if (!dst_hold_safe(dst))
 355                         dst = NULL;
 356
 357                 skb->_skb_refdst = (unsigned long)dst;
 358         }
 359 }
 360
 361
 362 /**
 363  *      __skb_tunnel_rx - prepare skb for rx reinsert
 364  *      @skb: buffer
 365  *      @dev: tunnel device
 366  *      @net: netns for packet i/o
 367  *
 368  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 369  *      so make some cleanups. (no accounting done)
 370  */
 371 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 372                                    struct net *net)
 373 {
 374         skb->dev = dev;
 375
 376         /*
 377          * Clear hash so that we can recalulate the hash for the
 378          * encapsulated packet, unless we have already determine the hash
 379          * over the L4 4-tuple.
 380          */
 381         skb_clear_hash_if_not_l4(skb);
 382         skb_set_queue_mapping(skb, 0);
 383         skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
 384 }
 385
 386 /**
 387  *      skb_tunnel_rx - prepare skb for rx reinsert
 388  *      @skb: buffer
 389  *      @dev: tunnel device
 390  *
 391  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 392  *      so make some cleanups, and perform accounting.
 393  *      Note: this accounting is not SMP safe.
 394  */
 395 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 396                                  struct net *net)
 397 {
 398         /* TODO : stats should be SMP safe */
 399         dev->stats.rx_packets++;
 400         dev->stats.rx_bytes += skb->len;
 401         __skb_tunnel_rx(skb, dev, net);
 402 }
 403
 404 static inline u32 dst_tclassid(const struct sk_buff *skb)
 405 {
 406 #ifdef CONFIG_IP_ROUTE_CLASSID
 407         const struct dst_entry *dst;
 408
 409         dst = skb_dst(skb);
 410         if (dst)
 411                 return dst->tclassid;
 412 #endif
 413         return 0;
 414 }
 415
 416 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
 417 static inline int dst_discard(struct sk_buff *skb)
 418 {
 419         return dst_discard_out(&init_net, skb->sk, skb);
 420 }
 421 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref,
 422                 int initial_obsolete, unsigned short flags);
 423 void dst_init(struct dst_entry *dst, struct dst_ops *ops,
 424               struct net_device *dev, int initial_ref, int initial_obsolete,
 425               unsigned short flags);
 426 void __dst_free(struct dst_entry *dst);
 427 struct dst_entry *dst_destroy(struct dst_entry *dst);
 428
 429 static inline void dst_free(struct dst_entry *dst)
 430 {
 431         if (dst->obsolete > 0)
 432                 return;
 433         if (!atomic_read(&dst->__refcnt)) {
 434                 dst = dst_destroy(dst);
 435                 if (!dst)
 436                         return;
 437         }
 438         __dst_free(dst);
 439 }
 440
 441 static inline void dst_rcu_free(struct rcu_head *head)
 442 {
 443         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 444         dst_free(dst);
 445 }
 446
 447 static inline void dst_confirm(struct dst_entry *dst)
 448 {
 449 }
 450
 451 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
 452 {
 453         struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
 454         return IS_ERR(n) ? NULL : n;
 455 }
 456
 457 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
 458                                                      struct sk_buff *skb)
 459 {
 460         struct neighbour *n =  dst->ops->neigh_lookup(dst, skb, NULL);
 461         return IS_ERR(n) ? NULL : n;
 462 }
 463
 464 static inline void dst_confirm_neigh(const struct dst_entry *dst,
 465                                      const void *daddr)
 466 {
 467         if (dst->ops->confirm_neigh)
 468                 dst->ops->confirm_neigh(dst, daddr);
 469 }
 470
 471 static inline void dst_link_failure(struct sk_buff *skb)
 472 {
 473         struct dst_entry *dst = skb_dst(skb);
 474         if (dst && dst->ops && dst->ops->link_failure)
 475                 dst->ops->link_failure(skb);
 476 }
 477
 478 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 479 {
 480         unsigned long expires = jiffies + timeout;
 481
 482         if (expires == 0)
 483                 expires = 1;
 484
 485         if (dst->expires == 0 || time_before(expires, dst->expires))
 486                 dst->expires = expires;
 487 }
 488
 489 /* Output packet to network from transport.  */
 490 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 491 {
 492         return skb_dst(skb)->output(net, sk, skb);
 493 }
 494
 495 /* Input packet from network to transport.  */
 496 static inline int dst_input(struct sk_buff *skb)
 497 {
 498         return skb_dst(skb)->input(skb);
 499 }
 500
 501 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 502 {
 503         if (dst->obsolete)
 504                 dst = dst->ops->check(dst, cookie);
 505         return dst;
 506 }
 507
 508 void dst_subsys_init(void);
 509
 510 /* Flags for xfrm_lookup flags argument. */
 511 enum {
 512         XFRM_LOOKUP_ICMP = 1 << 0,
 513         XFRM_LOOKUP_QUEUE = 1 << 1,
 514         XFRM_LOOKUP_KEEP_DST_REF = 1 << 2,
 515 };
 516
 517 struct flowi;
 518 #ifndef CONFIG_XFRM
 519 static inline struct dst_entry *xfrm_lookup(struct net *net,
 520                                             struct dst_entry *dst_orig,
 521                                             const struct flowi *fl,
 522                                             const struct sock *sk,
 523                                             int flags)
 524 {
 525         return dst_orig;
 526 }
 527
 528 static inline struct dst_entry *xfrm_lookup_route(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 xfrm_state *dst_xfrm(const struct dst_entry *dst)
 538 {
 539         return NULL;
 540 }
 541
 542 #else
 543 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
 544                               const struct flowi *fl, const struct sock *sk,
 545                               int flags);
 546
 547 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
 548                                     const struct flowi *fl, const struct sock *sk,
 549                                     int flags);
 550
 551 /* skb attached with this dst needs transformation if dst->xfrm is valid */
 552 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
 553 {
 554         return dst->xfrm;
 555 }
 556 #endif
 557
 558 #endif /* _NET_DST_H */