include/net/dst.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * net/dst.h    Protocol independent destination cache definitions.
   4  *
   5  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
   6  *
   7  */
   8
   9 #ifndef _NET_DST_H
  10 #define _NET_DST_H
  11
  12 #include <net/dst_ops.h>
  13 #include <linux/netdevice.h>
  14 #include <linux/rtnetlink.h>
  15 #include <linux/rcupdate.h>
  16 #include <linux/bug.h>
  17 #include <linux/jiffies.h>
  18 #include <linux/refcount.h>
  19 #include <net/neighbour.h>
  20 #include <asm/processor.h>
  21
  22 struct sk_buff;
  23
  24 struct dst_entry {
  25         struct net_device       *dev;
  26         struct  dst_ops         *ops;
  27         unsigned long           _metrics;
  28         unsigned long           expires;
  29 #ifdef CONFIG_XFRM
  30         struct xfrm_state       *xfrm;
  31 #else
  32         void                    *__pad1;
  33 #endif
  34         int                     (*input)(struct sk_buff *);
  35         int                     (*output)(struct net *net, struct sock *sk, struct sk_buff *skb);
  36
  37         unsigned short          flags;
  38 #define DST_NOXFRM              0x0002
  39 #define DST_NOPOLICY            0x0004
  40 #define DST_NOCOUNT             0x0008
  41 #define DST_FAKE_RTABLE         0x0010
  42 #define DST_XFRM_TUNNEL         0x0020
  43 #define DST_XFRM_QUEUE          0x0040
  44 #define DST_METADATA            0x0080
  45
  46         /* A non-zero value of dst->obsolete forces by-hand validation
  47          * of the route entry.  Positive values are set by the generic
  48          * dst layer to indicate that the entry has been forcefully
  49          * destroyed.
  50          *
  51          * Negative values are used by the implementation layer code to
  52          * force invocation of the dst_ops->check() method.
  53          */
  54         short                   obsolete;
  55 #define DST_OBSOLETE_NONE       0
  56 #define DST_OBSOLETE_DEAD       2
  57 #define DST_OBSOLETE_FORCE_CHK  -1
  58 #define DST_OBSOLETE_KILL       -2
  59         unsigned short          header_len;     /* more space at head required */
  60         unsigned short          trailer_len;    /* space to reserve at tail */
  61
  62         /*
  63          * __refcnt wants to be on a different cache line from
  64          * input/output/ops or performance tanks badly
  65          */
  66 #ifdef CONFIG_64BIT
  67         atomic_t                __refcnt;       /* 64-bit offset 64 */
  68 #endif
  69         int                     __use;
  70         unsigned long           lastuse;
  71         struct lwtunnel_state   *lwtstate;
  72         struct rcu_head         rcu_head;
  73         short                   error;
  74         short                   __pad;
  75         __u32                   tclassid;
  76 #ifndef CONFIG_64BIT
  77         atomic_t                __refcnt;       /* 32-bit offset 64 */
  78 #endif
  79 };
  80
  81 struct dst_metrics {
  82         u32             metrics[RTAX_MAX];
  83         refcount_t      refcnt;
  84 } __aligned(4);         /* Low pointer bits contain DST_METRICS_FLAGS */
  85 extern const struct dst_metrics dst_default_metrics;
  86
  87 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
  88
  89 #define DST_METRICS_READ_ONLY           0x1UL
  90 #define DST_METRICS_REFCOUNTED          0x2UL
  91 #define DST_METRICS_FLAGS               0x3UL
  92 #define __DST_METRICS_PTR(Y)    \
  93         ((u32 *)((Y) & ~DST_METRICS_FLAGS))
  94 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
  95
  96 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
  97 {
  98         return dst->_metrics & DST_METRICS_READ_ONLY;
  99 }
 100
 101 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
 102
 103 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
 104 {
 105         unsigned long val = dst->_metrics;
 106         if (!(val & DST_METRICS_READ_ONLY))
 107                 __dst_destroy_metrics_generic(dst, val);
 108 }
 109
 110 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
 111 {
 112         unsigned long p = dst->_metrics;
 113
 114         BUG_ON(!p);
 115
 116         if (p & DST_METRICS_READ_ONLY)
 117                 return dst->ops->cow_metrics(dst, p);
 118         return __DST_METRICS_PTR(p);
 119 }
 120
 121 /* This may only be invoked before the entry has reached global
 122  * visibility.
 123  */
 124 static inline void dst_init_metrics(struct dst_entry *dst,
 125                                     const u32 *src_metrics,
 126                                     bool read_only)
 127 {
 128         dst->_metrics = ((unsigned long) src_metrics) |
 129                 (read_only ? DST_METRICS_READ_ONLY : 0);
 130 }
 131
 132 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
 133 {
 134         u32 *dst_metrics = dst_metrics_write_ptr(dest);
 135
 136         if (dst_metrics) {
 137                 u32 *src_metrics = DST_METRICS_PTR(src);
 138
 139                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
 140         }
 141 }
 142
 143 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
 144 {
 145         return DST_METRICS_PTR(dst);
 146 }
 147
 148 static inline u32
 149 dst_metric_raw(const struct dst_entry *dst, const int metric)
 150 {
 151         u32 *p = DST_METRICS_PTR(dst);
 152
 153         return p[metric-1];
 154 }
 155
 156 static inline u32
 157 dst_metric(const struct dst_entry *dst, const int metric)
 158 {
 159         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
 160                      metric == RTAX_ADVMSS ||
 161                      metric == RTAX_MTU);
 162         return dst_metric_raw(dst, metric);
 163 }
 164
 165 static inline u32
 166 dst_metric_advmss(const struct dst_entry *dst)
 167 {
 168         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
 169
 170         if (!advmss)
 171                 advmss = dst->ops->default_advmss(dst);
 172
 173         return advmss;
 174 }
 175
 176 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
 177 {
 178         u32 *p = dst_metrics_write_ptr(dst);
 179
 180         if (p)
 181                 p[metric-1] = val;
 182 }
 183
 184 /* Kernel-internal feature bits that are unallocated in user space. */
 185 #define DST_FEATURE_ECN_CA      (1U << 31)
 186
 187 #define DST_FEATURE_MASK        (DST_FEATURE_ECN_CA)
 188 #define DST_FEATURE_ECN_MASK    (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN)
 189
 190 static inline u32
 191 dst_feature(const struct dst_entry *dst, u32 feature)
 192 {
 193         return dst_metric(dst, RTAX_FEATURES) & feature;
 194 }
 195
 196 static inline u32 dst_mtu(const struct dst_entry *dst)
 197 {
 198         return dst->ops->mtu(dst);
 199 }
 200
 201 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 202 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 203 {
 204         return msecs_to_jiffies(dst_metric(dst, metric));
 205 }
 206
 207 static inline u32
 208 dst_allfrag(const struct dst_entry *dst)
 209 {
 210         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
 211         return ret;
 212 }
 213
 214 static inline int
 215 dst_metric_locked(const struct dst_entry *dst, int metric)
 216 {
 217         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 218 }
 219
 220 static inline void dst_hold(struct dst_entry *dst)
 221 {
 222         /*
 223          * If your kernel compilation stops here, please check
 224          * the placement of __refcnt in struct dst_entry
 225          */
 226         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 227         WARN_ON(atomic_inc_not_zero(&dst->__refcnt) == 0);
 228 }
 229
 230 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
 231 {
 232         if (unlikely(time != dst->lastuse)) {
 233                 dst->__use++;
 234                 dst->lastuse = time;
 235         }
 236 }
 237
 238 static inline void dst_hold_and_use(struct dst_entry *dst, unsigned long time)
 239 {
 240         dst_hold(dst);
 241         dst_use_noref(dst, time);
 242 }
 243
 244 static inline struct dst_entry *dst_clone(struct dst_entry *dst)
 245 {
 246         if (dst)
 247                 dst_hold(dst);
 248         return dst;
 249 }
 250
 251 void dst_release(struct dst_entry *dst);
 252
 253 void dst_release_immediate(struct dst_entry *dst);
 254
 255 static inline void refdst_drop(unsigned long refdst)
 256 {
 257         if (!(refdst & SKB_DST_NOREF))
 258                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 259 }
 260
 261 /**
 262  * skb_dst_drop - drops skb dst
 263  * @skb: buffer
 264  *
 265  * Drops dst reference count if a reference was taken.
 266  */
 267 static inline void skb_dst_drop(struct sk_buff *skb)
 268 {
 269         if (skb->_skb_refdst) {
 270                 refdst_drop(skb->_skb_refdst);
 271                 skb->_skb_refdst = 0UL;
 272         }
 273 }
 274
 275 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst)
 276 {
 277         nskb->_skb_refdst = refdst;
 278         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 279                 dst_clone(skb_dst(nskb));
 280 }
 281
 282 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 283 {
 284         __skb_dst_copy(nskb, oskb->_skb_refdst);
 285 }
 286
 287 /**
 288  * dst_hold_safe - Take a reference on a dst if possible
 289  * @dst: pointer to dst entry
 290  *
 291  * This helper returns false if it could not safely
 292  * take a reference on a dst.
 293  */
 294 static inline bool dst_hold_safe(struct dst_entry *dst)
 295 {
 296         return atomic_inc_not_zero(&dst->__refcnt);
 297 }
 298
 299 /**
 300  * skb_dst_force - makes sure skb dst is refcounted
 301  * @skb: buffer
 302  *
 303  * If dst is not yet refcounted and not destroyed, grab a ref on it.
 304  * Returns true if dst is refcounted.
 305  */
 306 static inline bool skb_dst_force(struct sk_buff *skb)
 307 {
 308         if (skb_dst_is_noref(skb)) {
 309                 struct dst_entry *dst = skb_dst(skb);
 310
 311                 WARN_ON(!rcu_read_lock_held());
 312                 if (!dst_hold_safe(dst))
 313                         dst = NULL;
 314
 315                 skb->_skb_refdst = (unsigned long)dst;
 316         }
 317
 318         return skb->_skb_refdst != 0UL;
 319 }
 320
 321
 322 /**
 323  *      __skb_tunnel_rx - prepare skb for rx reinsert
 324  *      @skb: buffer
 325  *      @dev: tunnel device
 326  *      @net: netns for packet i/o
 327  *
 328  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 329  *      so make some cleanups. (no accounting done)
 330  */
 331 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 332                                    struct net *net)
 333 {
 334         skb->dev = dev;
 335
 336         /*
 337          * Clear hash so that we can recalulate the hash for the
 338          * encapsulated packet, unless we have already determine the hash
 339          * over the L4 4-tuple.
 340          */
 341         skb_clear_hash_if_not_l4(skb);
 342         skb_set_queue_mapping(skb, 0);
 343         skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
 344 }
 345
 346 /**
 347  *      skb_tunnel_rx - prepare skb for rx reinsert
 348  *      @skb: buffer
 349  *      @dev: tunnel device
 350  *      @net: netns for packet i/o
 351  *
 352  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 353  *      so make some cleanups, and perform accounting.
 354  *      Note: this accounting is not SMP safe.
 355  */
 356 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 357                                  struct net *net)
 358 {
 359         /* TODO : stats should be SMP safe */
 360         dev->stats.rx_packets++;
 361         dev->stats.rx_bytes += skb->len;
 362         __skb_tunnel_rx(skb, dev, net);
 363 }
 364
 365 static inline u32 dst_tclassid(const struct sk_buff *skb)
 366 {
 367 #ifdef CONFIG_IP_ROUTE_CLASSID
 368         const struct dst_entry *dst;
 369
 370         dst = skb_dst(skb);
 371         if (dst)
 372                 return dst->tclassid;
 373 #endif
 374         return 0;
 375 }
 376
 377 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
 378 static inline int dst_discard(struct sk_buff *skb)
 379 {
 380         return dst_discard_out(&init_net, skb->sk, skb);
 381 }
 382 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref,
 383                 int initial_obsolete, unsigned short flags);
 384 void dst_init(struct dst_entry *dst, struct dst_ops *ops,
 385               struct net_device *dev, int initial_ref, int initial_obsolete,
 386               unsigned short flags);
 387 struct dst_entry *dst_destroy(struct dst_entry *dst);
 388 void dst_dev_put(struct dst_entry *dst);
 389
 390 static inline void dst_confirm(struct dst_entry *dst)
 391 {
 392 }
 393
 394 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
 395 {
 396         struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
 397         return IS_ERR(n) ? NULL : n;
 398 }
 399
 400 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
 401                                                      struct sk_buff *skb)
 402 {
 403         struct neighbour *n =  dst->ops->neigh_lookup(dst, skb, NULL);
 404         return IS_ERR(n) ? NULL : n;
 405 }
 406
 407 static inline void dst_confirm_neigh(const struct dst_entry *dst,
 408                                      const void *daddr)
 409 {
 410         if (dst->ops->confirm_neigh)
 411                 dst->ops->confirm_neigh(dst, daddr);
 412 }
 413
 414 static inline void dst_link_failure(struct sk_buff *skb)
 415 {
 416         struct dst_entry *dst = skb_dst(skb);
 417         if (dst && dst->ops && dst->ops->link_failure)
 418                 dst->ops->link_failure(skb);
 419 }
 420
 421 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 422 {
 423         unsigned long expires = jiffies + timeout;
 424
 425         if (expires == 0)
 426                 expires = 1;
 427
 428         if (dst->expires == 0 || time_before(expires, dst->expires))
 429                 dst->expires = expires;
 430 }
 431
 432 /* Output packet to network from transport.  */
 433 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 434 {
 435         return skb_dst(skb)->output(net, sk, skb);
 436 }
 437
 438 /* Input packet from network to transport.  */
 439 static inline int dst_input(struct sk_buff *skb)
 440 {
 441         return skb_dst(skb)->input(skb);
 442 }
 443
 444 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 445 {
 446         if (dst->obsolete)
 447                 dst = dst->ops->check(dst, cookie);
 448         return dst;
 449 }
 450
 451 /* Flags for xfrm_lookup flags argument. */
 452 enum {
 453         XFRM_LOOKUP_ICMP = 1 << 0,
 454         XFRM_LOOKUP_QUEUE = 1 << 1,
 455         XFRM_LOOKUP_KEEP_DST_REF = 1 << 2,
 456 };
 457
 458 struct flowi;
 459 #ifndef CONFIG_XFRM
 460 static inline struct dst_entry *xfrm_lookup(struct net *net,
 461                                             struct dst_entry *dst_orig,
 462                                             const struct flowi *fl,
 463                                             const struct sock *sk,
 464                                             int flags)
 465 {
 466         return dst_orig;
 467 }
 468
 469 static inline struct dst_entry *
 470 xfrm_lookup_with_ifid(struct net *net, struct dst_entry *dst_orig,
 471                       const struct flowi *fl, const struct sock *sk,
 472                       int flags, u32 if_id)
 473 {
 474         return dst_orig;
 475 }
 476
 477 static inline struct dst_entry *xfrm_lookup_route(struct net *net,
 478                                                   struct dst_entry *dst_orig,
 479                                                   const struct flowi *fl,
 480                                                   const struct sock *sk,
 481                                                   int flags)
 482 {
 483         return dst_orig;
 484 }
 485
 486 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
 487 {
 488         return NULL;
 489 }
 490
 491 #else
 492 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
 493                               const struct flowi *fl, const struct sock *sk,
 494                               int flags);
 495
 496 struct dst_entry *xfrm_lookup_with_ifid(struct net *net,
 497                                         struct dst_entry *dst_orig,
 498                                         const struct flowi *fl,
 499                                         const struct sock *sk, int flags,
 500                                         u32 if_id);
 501
 502 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
 503                                     const struct flowi *fl, const 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 static inline void skb_dst_update_pmtu(struct sk_buff *skb, u32 mtu)
 514 {
 515         struct dst_entry *dst = skb_dst(skb);
 516
 517         if (dst && dst->ops->update_pmtu)
 518                 dst->ops->update_pmtu(dst, NULL, skb, mtu, true);
 519 }
 520
 521 /* update dst pmtu but not do neighbor confirm */
 522 static inline void skb_dst_update_pmtu_no_confirm(struct sk_buff *skb, u32 mtu)
 523 {
 524         struct dst_entry *dst = skb_dst(skb);
 525
 526         if (dst && dst->ops->update_pmtu)
 527                 dst->ops->update_pmtu(dst, NULL, skb, mtu, false);
 528 }
 529
 530 static inline void skb_tunnel_check_pmtu(struct sk_buff *skb,
 531                                          struct dst_entry *encap_dst,
 532                                          int headroom)
 533 {
 534         u32 encap_mtu = dst_mtu(encap_dst);
 535
 536         if (skb->len > encap_mtu - headroom)
 537                 skb_dst_update_pmtu_no_confirm(skb, encap_mtu - headroom);
 538 }
 539
 540 #endif /* _NET_DST_H */