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 <linux/rcuref.h>
  20 #include <net/neighbour.h>
  21 #include <asm/processor.h>
  22 #include <linux/indirect_call_wrapper.h>
  23
  24 struct sk_buff;
  25
  26 struct dst_entry {
  27         struct net_device       *dev;
  28         struct  dst_ops         *ops;
  29         unsigned long           _metrics;
  30         unsigned long           expires;
  31 #ifdef CONFIG_XFRM
  32         struct xfrm_state       *xfrm;
  33 #else
  34         void                    *__pad1;
  35 #endif
  36         int                     (*input)(struct sk_buff *);
  37         int                     (*output)(struct net *net, struct sock *sk, struct sk_buff *skb);
  38
  39         unsigned short          flags;
  40 #define DST_NOXFRM              0x0002
  41 #define DST_NOPOLICY            0x0004
  42 #define DST_NOCOUNT             0x0008
  43 #define DST_FAKE_RTABLE         0x0010
  44 #define DST_XFRM_TUNNEL         0x0020
  45 #define DST_XFRM_QUEUE          0x0040
  46 #define DST_METADATA            0x0080
  47
  48         /* A non-zero value of dst->obsolete forces by-hand validation
  49          * of the route entry.  Positive values are set by the generic
  50          * dst layer to indicate that the entry has been forcefully
  51          * destroyed.
  52          *
  53          * Negative values are used by the implementation layer code to
  54          * force invocation of the dst_ops->check() method.
  55          */
  56         short                   obsolete;
  57 #define DST_OBSOLETE_NONE       0
  58 #define DST_OBSOLETE_DEAD       2
  59 #define DST_OBSOLETE_FORCE_CHK  -1
  60 #define DST_OBSOLETE_KILL       -2
  61         unsigned short          header_len;     /* more space at head required */
  62         unsigned short          trailer_len;    /* space to reserve at tail */
  63
  64         /*
  65          * __rcuref wants to be on a different cache line from
  66          * input/output/ops or performance tanks badly
  67          */
  68 #ifdef CONFIG_64BIT
  69         rcuref_t                __rcuref;       /* 64-bit offset 64 */
  70 #endif
  71         int                     __use;
  72         unsigned long           lastuse;
  73         struct rcu_head         rcu_head;
  74         short                   error;
  75         short                   __pad;
  76         __u32                   tclassid;
  77 #ifndef CONFIG_64BIT
  78         struct lwtunnel_state   *lwtstate;
  79         rcuref_t                __rcuref;       /* 32-bit offset 64 */
  80 #endif
  81         netdevice_tracker       dev_tracker;
  82
  83         /*
  84          * Used by rtable and rt6_info. Moves lwtstate into the next cache
  85          * line on 64bit so that lwtstate does not cause false sharing with
  86          * __rcuref under contention of __rcuref. This also puts the
  87          * frequently accessed members of rtable and rt6_info out of the
  88          * __rcuref cache line.
  89          */
  90         struct list_head        rt_uncached;
  91         struct uncached_list    *rt_uncached_list;
  92 #ifdef CONFIG_64BIT
  93         struct lwtunnel_state   *lwtstate;
  94 #endif
  95 };
  96
  97 struct dst_metrics {
  98         u32             metrics[RTAX_MAX];
  99         refcount_t      refcnt;
 100 } __aligned(4);         /* Low pointer bits contain DST_METRICS_FLAGS */
 101 extern const struct dst_metrics dst_default_metrics;
 102
 103 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
 104
 105 #define DST_METRICS_READ_ONLY           0x1UL
 106 #define DST_METRICS_REFCOUNTED          0x2UL
 107 #define DST_METRICS_FLAGS               0x3UL
 108 #define __DST_METRICS_PTR(Y)    \
 109         ((u32 *)((Y) & ~DST_METRICS_FLAGS))
 110 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
 111
 112 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
 113 {
 114         return dst->_metrics & DST_METRICS_READ_ONLY;
 115 }
 116
 117 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
 118
 119 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
 120 {
 121         unsigned long val = dst->_metrics;
 122         if (!(val & DST_METRICS_READ_ONLY))
 123                 __dst_destroy_metrics_generic(dst, val);
 124 }
 125
 126 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
 127 {
 128         unsigned long p = dst->_metrics;
 129
 130         BUG_ON(!p);
 131
 132         if (p & DST_METRICS_READ_ONLY)
 133                 return dst->ops->cow_metrics(dst, p);
 134         return __DST_METRICS_PTR(p);
 135 }
 136
 137 /* This may only be invoked before the entry has reached global
 138  * visibility.
 139  */
 140 static inline void dst_init_metrics(struct dst_entry *dst,
 141                                     const u32 *src_metrics,
 142                                     bool read_only)
 143 {
 144         dst->_metrics = ((unsigned long) src_metrics) |
 145                 (read_only ? DST_METRICS_READ_ONLY : 0);
 146 }
 147
 148 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
 149 {
 150         u32 *dst_metrics = dst_metrics_write_ptr(dest);
 151
 152         if (dst_metrics) {
 153                 u32 *src_metrics = DST_METRICS_PTR(src);
 154
 155                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
 156         }
 157 }
 158
 159 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
 160 {
 161         return DST_METRICS_PTR(dst);
 162 }
 163
 164 static inline u32
 165 dst_metric_raw(const struct dst_entry *dst, const int metric)
 166 {
 167         u32 *p = DST_METRICS_PTR(dst);
 168
 169         return p[metric-1];
 170 }
 171
 172 static inline u32
 173 dst_metric(const struct dst_entry *dst, const int metric)
 174 {
 175         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
 176                      metric == RTAX_ADVMSS ||
 177                      metric == RTAX_MTU);
 178         return dst_metric_raw(dst, metric);
 179 }
 180
 181 static inline u32
 182 dst_metric_advmss(const struct dst_entry *dst)
 183 {
 184         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
 185
 186         if (!advmss)
 187                 advmss = dst->ops->default_advmss(dst);
 188
 189         return advmss;
 190 }
 191
 192 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
 193 {
 194         u32 *p = dst_metrics_write_ptr(dst);
 195
 196         if (p)
 197                 p[metric-1] = val;
 198 }
 199
 200 /* Kernel-internal feature bits that are unallocated in user space. */
 201 #define DST_FEATURE_ECN_CA      (1U << 31)
 202
 203 #define DST_FEATURE_MASK        (DST_FEATURE_ECN_CA)
 204 #define DST_FEATURE_ECN_MASK    (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN)
 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 INDIRECT_CALLABLE_DECLARE(unsigned int ip6_mtu(const struct dst_entry *));
 213 INDIRECT_CALLABLE_DECLARE(unsigned int ipv4_mtu(const struct dst_entry *));
 214 static inline u32 dst_mtu(const struct dst_entry *dst)
 215 {
 216         return INDIRECT_CALL_INET(dst->ops->mtu, ip6_mtu, ipv4_mtu, dst);
 217 }
 218
 219 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 220 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 221 {
 222         return msecs_to_jiffies(dst_metric(dst, metric));
 223 }
 224
 225 static inline int
 226 dst_metric_locked(const struct dst_entry *dst, int metric)
 227 {
 228         return dst_metric(dst, RTAX_LOCK) & (1 << metric);
 229 }
 230
 231 static inline void dst_hold(struct dst_entry *dst)
 232 {
 233         /*
 234          * If your kernel compilation stops here, please check
 235          * the placement of __rcuref in struct dst_entry
 236          */
 237         BUILD_BUG_ON(offsetof(struct dst_entry, __rcuref) & 63);
 238         WARN_ON(!rcuref_get(&dst->__rcuref));
 239 }
 240
 241 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
 242 {
 243         if (unlikely(time != dst->lastuse)) {
 244                 dst->__use++;
 245                 dst->lastuse = time;
 246         }
 247 }
 248
 249 static inline struct dst_entry *dst_clone(struct dst_entry *dst)
 250 {
 251         if (dst)
 252                 dst_hold(dst);
 253         return dst;
 254 }
 255
 256 void dst_release(struct dst_entry *dst);
 257
 258 void dst_release_immediate(struct dst_entry *dst);
 259
 260 static inline void refdst_drop(unsigned long refdst)
 261 {
 262         if (!(refdst & SKB_DST_NOREF))
 263                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 264 }
 265
 266 /**
 267  * skb_dst_drop - drops skb dst
 268  * @skb: buffer
 269  *
 270  * Drops dst reference count if a reference was taken.
 271  */
 272 static inline void skb_dst_drop(struct sk_buff *skb)
 273 {
 274         if (skb->_skb_refdst) {
 275                 refdst_drop(skb->_skb_refdst);
 276                 skb->_skb_refdst = 0UL;
 277         }
 278 }
 279
 280 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst)
 281 {
 282         nskb->slow_gro |= !!refdst;
 283         nskb->_skb_refdst = refdst;
 284         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 285                 dst_clone(skb_dst(nskb));
 286 }
 287
 288 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 289 {
 290         __skb_dst_copy(nskb, oskb->_skb_refdst);
 291 }
 292
 293 /**
 294  * dst_hold_safe - Take a reference on a dst if possible
 295  * @dst: pointer to dst entry
 296  *
 297  * This helper returns false if it could not safely
 298  * take a reference on a dst.
 299  */
 300 static inline bool dst_hold_safe(struct dst_entry *dst)
 301 {
 302         return rcuref_get(&dst->__rcuref);
 303 }
 304
 305 /**
 306  * skb_dst_force - makes sure skb dst is refcounted
 307  * @skb: buffer
 308  *
 309  * If dst is not yet refcounted and not destroyed, grab a ref on it.
 310  * Returns true if dst is refcounted.
 311  */
 312 static inline bool skb_dst_force(struct sk_buff *skb)
 313 {
 314         if (skb_dst_is_noref(skb)) {
 315                 struct dst_entry *dst = skb_dst(skb);
 316
 317                 WARN_ON(!rcu_read_lock_held());
 318                 if (!dst_hold_safe(dst))
 319                         dst = NULL;
 320
 321                 skb->_skb_refdst = (unsigned long)dst;
 322                 skb->slow_gro |= !!dst;
 323         }
 324
 325         return skb->_skb_refdst != 0UL;
 326 }
 327
 328
 329 /**
 330  *      __skb_tunnel_rx - prepare skb for rx reinsert
 331  *      @skb: buffer
 332  *      @dev: tunnel device
 333  *      @net: netns for packet i/o
 334  *
 335  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 336  *      so make some cleanups. (no accounting done)
 337  */
 338 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 339                                    struct net *net)
 340 {
 341         skb->dev = dev;
 342
 343         /*
 344          * Clear hash so that we can recalculate the hash for the
 345          * encapsulated packet, unless we have already determine the hash
 346          * over the L4 4-tuple.
 347          */
 348         skb_clear_hash_if_not_l4(skb);
 349         skb_set_queue_mapping(skb, 0);
 350         skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
 351 }
 352
 353 /**
 354  *      skb_tunnel_rx - prepare skb for rx reinsert
 355  *      @skb: buffer
 356  *      @dev: tunnel device
 357  *      @net: netns for packet i/o
 358  *
 359  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 360  *      so make some cleanups, and perform accounting.
 361  *      Note: this accounting is not SMP safe.
 362  */
 363 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 364                                  struct net *net)
 365 {
 366         DEV_STATS_INC(dev, rx_packets);
 367         DEV_STATS_ADD(dev, rx_bytes, skb->len);
 368         __skb_tunnel_rx(skb, dev, net);
 369 }
 370
 371 static inline u32 dst_tclassid(const struct sk_buff *skb)
 372 {
 373 #ifdef CONFIG_IP_ROUTE_CLASSID
 374         const struct dst_entry *dst;
 375
 376         dst = skb_dst(skb);
 377         if (dst)
 378                 return dst->tclassid;
 379 #endif
 380         return 0;
 381 }
 382
 383 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
 384 static inline int dst_discard(struct sk_buff *skb)
 385 {
 386         return dst_discard_out(&init_net, skb->sk, skb);
 387 }
 388 void *dst_alloc(struct dst_ops *ops, struct net_device *dev,
 389                 int initial_obsolete, unsigned short flags);
 390 void dst_init(struct dst_entry *dst, struct dst_ops *ops,
 391               struct net_device *dev, int initial_obsolete,
 392               unsigned short flags);
 393 void dst_dev_put(struct dst_entry *dst);
 394
 395 static inline void dst_confirm(struct dst_entry *dst)
 396 {
 397 }
 398
 399 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
 400 {
 401         struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
 402         return IS_ERR(n) ? NULL : n;
 403 }
 404
 405 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
 406                                                      struct sk_buff *skb)
 407 {
 408         struct neighbour *n;
 409
 410         if (WARN_ON_ONCE(!dst->ops->neigh_lookup))
 411                 return NULL;
 412
 413         n = dst->ops->neigh_lookup(dst, skb, NULL);
 414
 415         return IS_ERR(n) ? NULL : n;
 416 }
 417
 418 static inline void dst_confirm_neigh(const struct dst_entry *dst,
 419                                      const void *daddr)
 420 {
 421         if (dst->ops->confirm_neigh)
 422                 dst->ops->confirm_neigh(dst, daddr);
 423 }
 424
 425 static inline void dst_link_failure(struct sk_buff *skb)
 426 {
 427         struct dst_entry *dst = skb_dst(skb);
 428         if (dst && dst->ops && dst->ops->link_failure)
 429                 dst->ops->link_failure(skb);
 430 }
 431
 432 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 433 {
 434         unsigned long expires = jiffies + timeout;
 435
 436         if (expires == 0)
 437                 expires = 1;
 438
 439         if (dst->expires == 0 || time_before(expires, dst->expires))
 440                 dst->expires = expires;
 441 }
 442
 443 INDIRECT_CALLABLE_DECLARE(int ip6_output(struct net *, struct sock *,
 444                                          struct sk_buff *));
 445 INDIRECT_CALLABLE_DECLARE(int ip_output(struct net *, struct sock *,
 446                                          struct sk_buff *));
 447 /* Output packet to network from transport.  */
 448 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 449 {
 450         return INDIRECT_CALL_INET(skb_dst(skb)->output,
 451                                   ip6_output, ip_output,
 452                                   net, sk, skb);
 453 }
 454
 455 INDIRECT_CALLABLE_DECLARE(int ip6_input(struct sk_buff *));
 456 INDIRECT_CALLABLE_DECLARE(int ip_local_deliver(struct sk_buff *));
 457 /* Input packet from network to transport.  */
 458 static inline int dst_input(struct sk_buff *skb)
 459 {
 460         return INDIRECT_CALL_INET(skb_dst(skb)->input,
 461                                   ip6_input, ip_local_deliver, skb);
 462 }
 463
 464 INDIRECT_CALLABLE_DECLARE(struct dst_entry *ip6_dst_check(struct dst_entry *,
 465                                                           u32));
 466 INDIRECT_CALLABLE_DECLARE(struct dst_entry *ipv4_dst_check(struct dst_entry *,
 467                                                            u32));
 468 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 469 {
 470         if (dst->obsolete)
 471                 dst = INDIRECT_CALL_INET(dst->ops->check, ip6_dst_check,
 472                                          ipv4_dst_check, dst, cookie);
 473         return dst;
 474 }
 475
 476 /* Flags for xfrm_lookup flags argument. */
 477 enum {
 478         XFRM_LOOKUP_ICMP = 1 << 0,
 479         XFRM_LOOKUP_QUEUE = 1 << 1,
 480         XFRM_LOOKUP_KEEP_DST_REF = 1 << 2,
 481 };
 482
 483 struct flowi;
 484 #ifndef CONFIG_XFRM
 485 static inline struct dst_entry *xfrm_lookup(struct net *net,
 486                                             struct dst_entry *dst_orig,
 487                                             const struct flowi *fl,
 488                                             const struct sock *sk,
 489                                             int flags)
 490 {
 491         return dst_orig;
 492 }
 493
 494 static inline struct dst_entry *
 495 xfrm_lookup_with_ifid(struct net *net, struct dst_entry *dst_orig,
 496                       const struct flowi *fl, const struct sock *sk,
 497                       int flags, u32 if_id)
 498 {
 499         return dst_orig;
 500 }
 501
 502 static inline struct dst_entry *xfrm_lookup_route(struct net *net,
 503                                                   struct dst_entry *dst_orig,
 504                                                   const struct flowi *fl,
 505                                                   const struct sock *sk,
 506                                                   int flags)
 507 {
 508         return dst_orig;
 509 }
 510
 511 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
 512 {
 513         return NULL;
 514 }
 515
 516 #else
 517 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
 518                               const struct flowi *fl, const struct sock *sk,
 519                               int flags);
 520
 521 struct dst_entry *xfrm_lookup_with_ifid(struct net *net,
 522                                         struct dst_entry *dst_orig,
 523                                         const struct flowi *fl,
 524                                         const struct sock *sk, int flags,
 525                                         u32 if_id);
 526
 527 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
 528                                     const struct flowi *fl, const struct sock *sk,
 529                                     int flags);
 530
 531 /* skb attached with this dst needs transformation if dst->xfrm is valid */
 532 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
 533 {
 534         return dst->xfrm;
 535 }
 536 #endif
 537
 538 static inline void skb_dst_update_pmtu(struct sk_buff *skb, u32 mtu)
 539 {
 540         struct dst_entry *dst = skb_dst(skb);
 541
 542         if (dst && dst->ops->update_pmtu)
 543                 dst->ops->update_pmtu(dst, NULL, skb, mtu, true);
 544 }
 545
 546 /* update dst pmtu but not do neighbor confirm */
 547 static inline void skb_dst_update_pmtu_no_confirm(struct sk_buff *skb, u32 mtu)
 548 {
 549         struct dst_entry *dst = skb_dst(skb);
 550
 551         if (dst && dst->ops->update_pmtu)
 552                 dst->ops->update_pmtu(dst, NULL, skb, mtu, false);
 553 }
 554
 555 struct dst_entry *dst_blackhole_check(struct dst_entry *dst, u32 cookie);
 556 void dst_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
 557                                struct sk_buff *skb, u32 mtu, bool confirm_neigh);
 558 void dst_blackhole_redirect(struct dst_entry *dst, struct sock *sk,
 559                             struct sk_buff *skb);
 560 u32 *dst_blackhole_cow_metrics(struct dst_entry *dst, unsigned long old);
 561 struct neighbour *dst_blackhole_neigh_lookup(const struct dst_entry *dst,
 562                                              struct sk_buff *skb,
 563                                              const void *daddr);
 564 unsigned int dst_blackhole_mtu(const struct dst_entry *dst);
 565
 566 #endif /* _NET_DST_H */