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 #include <linux/indirect_call_wrapper.h>
  22
  23 struct sk_buff;
  24
  25 struct dst_entry {
  26         struct net_device       *dev;
  27         struct  dst_ops         *ops;
  28         unsigned long           _metrics;
  29         unsigned long           expires;
  30 #ifdef CONFIG_XFRM
  31         struct xfrm_state       *xfrm;
  32 #else
  33         void                    *__pad1;
  34 #endif
  35         int                     (*input)(struct sk_buff *);
  36         int                     (*output)(struct net *net, struct sock *sk, struct sk_buff *skb);
  37
  38         unsigned short          flags;
  39 #define DST_NOXFRM              0x0002
  40 #define DST_NOPOLICY            0x0004
  41 #define DST_NOCOUNT             0x0008
  42 #define DST_FAKE_RTABLE         0x0010
  43 #define DST_XFRM_TUNNEL         0x0020
  44 #define DST_XFRM_QUEUE          0x0040
  45 #define DST_METADATA            0x0080
  46
  47         /* A non-zero value of dst->obsolete forces by-hand validation
  48          * of the route entry.  Positive values are set by the generic
  49          * dst layer to indicate that the entry has been forcefully
  50          * destroyed.
  51          *
  52          * Negative values are used by the implementation layer code to
  53          * force invocation of the dst_ops->check() method.
  54          */
  55         short                   obsolete;
  56 #define DST_OBSOLETE_NONE       0
  57 #define DST_OBSOLETE_DEAD       2
  58 #define DST_OBSOLETE_FORCE_CHK  -1
  59 #define DST_OBSOLETE_KILL       -2
  60         unsigned short          header_len;     /* more space at head required */
  61         unsigned short          trailer_len;    /* space to reserve at tail */
  62
  63         /*
  64          * __refcnt wants to be on a different cache line from
  65          * input/output/ops or performance tanks badly
  66          */
  67 #ifdef CONFIG_64BIT
  68         atomic_t                __refcnt;       /* 64-bit offset 64 */
  69 #endif
  70         int                     __use;
  71         unsigned long           lastuse;
  72         struct lwtunnel_state   *lwtstate;
  73         struct rcu_head         rcu_head;
  74         short                   error;
  75         short                   __pad;
  76         __u32                   tclassid;
  77 #ifndef CONFIG_64BIT
  78         atomic_t                __refcnt;       /* 32-bit offset 64 */
  79 #endif
  80 };
  81
  82 struct dst_metrics {
  83         u32             metrics[RTAX_MAX];
  84         refcount_t      refcnt;
  85 } __aligned(4);         /* Low pointer bits contain DST_METRICS_FLAGS */
  86 extern const struct dst_metrics dst_default_metrics;
  87
  88 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
  89
  90 #define DST_METRICS_READ_ONLY           0x1UL
  91 #define DST_METRICS_REFCOUNTED          0x2UL
  92 #define DST_METRICS_FLAGS               0x3UL
  93 #define __DST_METRICS_PTR(Y)    \
  94         ((u32 *)((Y) & ~DST_METRICS_FLAGS))
  95 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
  96
  97 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
  98 {
  99         return dst->_metrics & DST_METRICS_READ_ONLY;
 100 }
 101
 102 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
 103
 104 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
 105 {
 106         unsigned long val = dst->_metrics;
 107         if (!(val & DST_METRICS_READ_ONLY))
 108                 __dst_destroy_metrics_generic(dst, val);
 109 }
 110
 111 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
 112 {
 113         unsigned long p = dst->_metrics;
 114
 115         BUG_ON(!p);
 116
 117         if (p & DST_METRICS_READ_ONLY)
 118                 return dst->ops->cow_metrics(dst, p);
 119         return __DST_METRICS_PTR(p);
 120 }
 121
 122 /* This may only be invoked before the entry has reached global
 123  * visibility.
 124  */
 125 static inline void dst_init_metrics(struct dst_entry *dst,
 126                                     const u32 *src_metrics,
 127                                     bool read_only)
 128 {
 129         dst->_metrics = ((unsigned long) src_metrics) |
 130                 (read_only ? DST_METRICS_READ_ONLY : 0);
 131 }
 132
 133 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
 134 {
 135         u32 *dst_metrics = dst_metrics_write_ptr(dest);
 136
 137         if (dst_metrics) {
 138                 u32 *src_metrics = DST_METRICS_PTR(src);
 139
 140                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
 141         }
 142 }
 143
 144 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
 145 {
 146         return DST_METRICS_PTR(dst);
 147 }
 148
 149 static inline u32
 150 dst_metric_raw(const struct dst_entry *dst, const int metric)
 151 {
 152         u32 *p = DST_METRICS_PTR(dst);
 153
 154         return p[metric-1];
 155 }
 156
 157 static inline u32
 158 dst_metric(const struct dst_entry *dst, const int metric)
 159 {
 160         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
 161                      metric == RTAX_ADVMSS ||
 162                      metric == RTAX_MTU);
 163         return dst_metric_raw(dst, metric);
 164 }
 165
 166 static inline u32
 167 dst_metric_advmss(const struct dst_entry *dst)
 168 {
 169         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
 170
 171         if (!advmss)
 172                 advmss = dst->ops->default_advmss(dst);
 173
 174         return advmss;
 175 }
 176
 177 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
 178 {
 179         u32 *p = dst_metrics_write_ptr(dst);
 180
 181         if (p)
 182                 p[metric-1] = val;
 183 }
 184
 185 /* Kernel-internal feature bits that are unallocated in user space. */
 186 #define DST_FEATURE_ECN_CA      (1U << 31)
 187
 188 #define DST_FEATURE_MASK        (DST_FEATURE_ECN_CA)
 189 #define DST_FEATURE_ECN_MASK    (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN)
 190
 191 static inline u32
 192 dst_feature(const struct dst_entry *dst, u32 feature)
 193 {
 194         return dst_metric(dst, RTAX_FEATURES) & feature;
 195 }
 196
 197 INDIRECT_CALLABLE_DECLARE(unsigned int ip6_mtu(const struct dst_entry *));
 198 INDIRECT_CALLABLE_DECLARE(unsigned int ipv4_mtu(const struct dst_entry *));
 199 static inline u32 dst_mtu(const struct dst_entry *dst)
 200 {
 201         return INDIRECT_CALL_INET(dst->ops->mtu, ip6_mtu, ipv4_mtu, dst);
 202 }
 203
 204 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 205 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 206 {
 207         return msecs_to_jiffies(dst_metric(dst, metric));
 208 }
 209
 210 static inline u32
 211 dst_allfrag(const struct dst_entry *dst)
 212 {
 213         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
 214         return ret;
 215 }
 216
 217 static inline int
 218 dst_metric_locked(const struct dst_entry *dst, int metric)
 219 {
 220         return dst_metric(dst, RTAX_LOCK) & (1 << metric);
 221 }
 222
 223 static inline void dst_hold(struct dst_entry *dst)
 224 {
 225         /*
 226          * If your kernel compilation stops here, please check
 227          * the placement of __refcnt in struct dst_entry
 228          */
 229         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 230         WARN_ON(atomic_inc_not_zero(&dst->__refcnt) == 0);
 231 }
 232
 233 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
 234 {
 235         if (unlikely(time != dst->lastuse)) {
 236                 dst->__use++;
 237                 dst->lastuse = time;
 238         }
 239 }
 240
 241 static inline void dst_hold_and_use(struct dst_entry *dst, unsigned long time)
 242 {
 243         dst_hold(dst);
 244         dst_use_noref(dst, time);
 245 }
 246
 247 static inline struct dst_entry *dst_clone(struct dst_entry *dst)
 248 {
 249         if (dst)
 250                 dst_hold(dst);
 251         return dst;
 252 }
 253
 254 void dst_release(struct dst_entry *dst);
 255
 256 void dst_release_immediate(struct dst_entry *dst);
 257
 258 static inline void refdst_drop(unsigned long refdst)
 259 {
 260         if (!(refdst & SKB_DST_NOREF))
 261                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 262 }
 263
 264 /**
 265  * skb_dst_drop - drops skb dst
 266  * @skb: buffer
 267  *
 268  * Drops dst reference count if a reference was taken.
 269  */
 270 static inline void skb_dst_drop(struct sk_buff *skb)
 271 {
 272         if (skb->_skb_refdst) {
 273                 refdst_drop(skb->_skb_refdst);
 274                 skb->_skb_refdst = 0UL;
 275         }
 276 }
 277
 278 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst)
 279 {
 280         nskb->slow_gro |= !!refdst;
 281         nskb->_skb_refdst = refdst;
 282         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 283                 dst_clone(skb_dst(nskb));
 284 }
 285
 286 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 287 {
 288         __skb_dst_copy(nskb, oskb->_skb_refdst);
 289 }
 290
 291 /**
 292  * dst_hold_safe - Take a reference on a dst if possible
 293  * @dst: pointer to dst entry
 294  *
 295  * This helper returns false if it could not safely
 296  * take a reference on a dst.
 297  */
 298 static inline bool dst_hold_safe(struct dst_entry *dst)
 299 {
 300         return atomic_inc_not_zero(&dst->__refcnt);
 301 }
 302
 303 /**
 304  * skb_dst_force - makes sure skb dst is refcounted
 305  * @skb: buffer
 306  *
 307  * If dst is not yet refcounted and not destroyed, grab a ref on it.
 308  * Returns true if dst is refcounted.
 309  */
 310 static inline bool skb_dst_force(struct sk_buff *skb)
 311 {
 312         if (skb_dst_is_noref(skb)) {
 313                 struct dst_entry *dst = skb_dst(skb);
 314
 315                 WARN_ON(!rcu_read_lock_held());
 316                 if (!dst_hold_safe(dst))
 317                         dst = NULL;
 318
 319                 skb->_skb_refdst = (unsigned long)dst;
 320                 skb->slow_gro |= !!dst;
 321         }
 322
 323         return skb->_skb_refdst != 0UL;
 324 }
 325
 326
 327 /**
 328  *      __skb_tunnel_rx - prepare skb for rx reinsert
 329  *      @skb: buffer
 330  *      @dev: tunnel device
 331  *      @net: netns for packet i/o
 332  *
 333  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 334  *      so make some cleanups. (no accounting done)
 335  */
 336 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 337                                    struct net *net)
 338 {
 339         skb->dev = dev;
 340
 341         /*
 342          * Clear hash so that we can recalulate the hash for the
 343          * encapsulated packet, unless we have already determine the hash
 344          * over the L4 4-tuple.
 345          */
 346         skb_clear_hash_if_not_l4(skb);
 347         skb_set_queue_mapping(skb, 0);
 348         skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
 349 }
 350
 351 /**
 352  *      skb_tunnel_rx - prepare skb for rx reinsert
 353  *      @skb: buffer
 354  *      @dev: tunnel device
 355  *      @net: netns for packet i/o
 356  *
 357  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 358  *      so make some cleanups, and perform accounting.
 359  *      Note: this accounting is not SMP safe.
 360  */
 361 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 362                                  struct net *net)
 363 {
 364         /* TODO : stats should be SMP safe */
 365         dev->stats.rx_packets++;
 366         dev->stats.rx_bytes += skb->len;
 367         __skb_tunnel_rx(skb, dev, net);
 368 }
 369
 370 static inline u32 dst_tclassid(const struct sk_buff *skb)
 371 {
 372 #ifdef CONFIG_IP_ROUTE_CLASSID
 373         const struct dst_entry *dst;
 374
 375         dst = skb_dst(skb);
 376         if (dst)
 377                 return dst->tclassid;
 378 #endif
 379         return 0;
 380 }
 381
 382 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
 383 static inline int dst_discard(struct sk_buff *skb)
 384 {
 385         return dst_discard_out(&init_net, skb->sk, skb);
 386 }
 387 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref,
 388                 int initial_obsolete, unsigned short flags);
 389 void dst_init(struct dst_entry *dst, struct dst_ops *ops,
 390               struct net_device *dev, int initial_ref, int initial_obsolete,
 391               unsigned short flags);
 392 struct dst_entry *dst_destroy(struct dst_entry *dst);
 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 */