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 #define DST_GC_MIN      (HZ/10)
  23 #define DST_GC_INC      (HZ/2)
  24 #define DST_GC_MAX      (120*HZ)
  25
  26 /* Each dst_entry has reference count and sits in some parent list(s).
  27  * When it is removed from parent list, it is "freed" (dst_free).
  28  * After this it enters dead state (dst->obsolete > 0) and if its refcnt
  29  * is zero, it can be destroyed immediately, otherwise it is added
  30  * to gc list and garbage collector periodically checks the refcnt.
  31  */
  32
  33 struct sk_buff;
  34
  35 struct dst_entry {
  36         struct net_device       *dev;
  37         struct rcu_head         rcu_head;
  38         struct dst_entry        *child;
  39         struct  dst_ops         *ops;
  40         unsigned long           _metrics;
  41         unsigned long           expires;
  42         struct dst_entry        *path;
  43         struct dst_entry        *from;
  44 #ifdef CONFIG_XFRM
  45         struct xfrm_state       *xfrm;
  46 #else
  47         void                    *__pad1;
  48 #endif
  49         int                     (*input)(struct sk_buff *);
  50         int                     (*output)(struct net *net, struct sock *sk, struct sk_buff *skb);
  51
  52         unsigned short          flags;
  53 #define DST_HOST                0x0001
  54 #define DST_NOXFRM              0x0002
  55 #define DST_NOPOLICY            0x0004
  56 #define DST_NOCOUNT             0x0008
  57 #define DST_FAKE_RTABLE         0x0010
  58 #define DST_XFRM_TUNNEL         0x0020
  59 #define DST_XFRM_QUEUE          0x0040
  60 #define DST_METADATA            0x0080
  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         refcount_t      refcnt;
 113 } __aligned(4);         /* Low pointer bits contain DST_METRICS_FLAGS */
 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         WARN_ON(atomic_inc_not_zero(&dst->__refcnt) == 0);
 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                 dst_hold(dst);
 276         return dst;
 277 }
 278
 279 void dst_release(struct dst_entry *dst);
 280
 281 void dst_release_immediate(struct dst_entry *dst);
 282
 283 static inline void refdst_drop(unsigned long refdst)
 284 {
 285         if (!(refdst & SKB_DST_NOREF))
 286                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 287 }
 288
 289 /**
 290  * skb_dst_drop - drops skb dst
 291  * @skb: buffer
 292  *
 293  * Drops dst reference count if a reference was taken.
 294  */
 295 static inline void skb_dst_drop(struct sk_buff *skb)
 296 {
 297         if (skb->_skb_refdst) {
 298                 refdst_drop(skb->_skb_refdst);
 299                 skb->_skb_refdst = 0UL;
 300         }
 301 }
 302
 303 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst)
 304 {
 305         nskb->_skb_refdst = refdst;
 306         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 307                 dst_clone(skb_dst(nskb));
 308 }
 309
 310 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 311 {
 312         __skb_dst_copy(nskb, oskb->_skb_refdst);
 313 }
 314
 315 /**
 316  * dst_hold_safe - Take a reference on a dst if possible
 317  * @dst: pointer to dst entry
 318  *
 319  * This helper returns false if it could not safely
 320  * take a reference on a dst.
 321  */
 322 static inline bool dst_hold_safe(struct dst_entry *dst)
 323 {
 324         return atomic_inc_not_zero(&dst->__refcnt);
 325 }
 326
 327 /**
 328  * skb_dst_force - makes sure skb dst is refcounted
 329  * @skb: buffer
 330  *
 331  * If dst is not yet refcounted and not destroyed, grab a ref on it.
 332  * Returns true if dst is refcounted.
 333  */
 334 static inline bool skb_dst_force(struct sk_buff *skb)
 335 {
 336         if (skb_dst_is_noref(skb)) {
 337                 struct dst_entry *dst = skb_dst(skb);
 338
 339                 WARN_ON(!rcu_read_lock_held());
 340                 if (!dst_hold_safe(dst))
 341                         dst = NULL;
 342
 343                 skb->_skb_refdst = (unsigned long)dst;
 344         }
 345
 346         return skb->_skb_refdst != 0UL;
 347 }
 348
 349
 350 /**
 351  *      __skb_tunnel_rx - prepare skb for rx reinsert
 352  *      @skb: buffer
 353  *      @dev: tunnel device
 354  *      @net: netns for packet i/o
 355  *
 356  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 357  *      so make some cleanups. (no accounting done)
 358  */
 359 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 360                                    struct net *net)
 361 {
 362         skb->dev = dev;
 363
 364         /*
 365          * Clear hash so that we can recalulate the hash for the
 366          * encapsulated packet, unless we have already determine the hash
 367          * over the L4 4-tuple.
 368          */
 369         skb_clear_hash_if_not_l4(skb);
 370         skb_set_queue_mapping(skb, 0);
 371         skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
 372 }
 373
 374 /**
 375  *      skb_tunnel_rx - prepare skb for rx reinsert
 376  *      @skb: buffer
 377  *      @dev: tunnel device
 378  *
 379  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 380  *      so make some cleanups, and perform accounting.
 381  *      Note: this accounting is not SMP safe.
 382  */
 383 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 384                                  struct net *net)
 385 {
 386         /* TODO : stats should be SMP safe */
 387         dev->stats.rx_packets++;
 388         dev->stats.rx_bytes += skb->len;
 389         __skb_tunnel_rx(skb, dev, net);
 390 }
 391
 392 static inline u32 dst_tclassid(const struct sk_buff *skb)
 393 {
 394 #ifdef CONFIG_IP_ROUTE_CLASSID
 395         const struct dst_entry *dst;
 396
 397         dst = skb_dst(skb);
 398         if (dst)
 399                 return dst->tclassid;
 400 #endif
 401         return 0;
 402 }
 403
 404 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
 405 static inline int dst_discard(struct sk_buff *skb)
 406 {
 407         return dst_discard_out(&init_net, skb->sk, skb);
 408 }
 409 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref,
 410                 int initial_obsolete, unsigned short flags);
 411 void dst_init(struct dst_entry *dst, struct dst_ops *ops,
 412               struct net_device *dev, int initial_ref, int initial_obsolete,
 413               unsigned short flags);
 414 struct dst_entry *dst_destroy(struct dst_entry *dst);
 415 void dst_dev_put(struct dst_entry *dst);
 416
 417 static inline void dst_confirm(struct dst_entry *dst)
 418 {
 419 }
 420
 421 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
 422 {
 423         struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
 424         return IS_ERR(n) ? NULL : n;
 425 }
 426
 427 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
 428                                                      struct sk_buff *skb)
 429 {
 430         struct neighbour *n = NULL;
 431
 432         /* The packets from tunnel devices (eg bareudp) may have only
 433          * metadata in the dst pointer of skb. Hence a pointer check of
 434          * neigh_lookup is needed.
 435          */
 436         if (dst->ops->neigh_lookup)
 437                 n = dst->ops->neigh_lookup(dst, skb, NULL);
 438
 439         return IS_ERR(n) ? NULL : n;
 440 }
 441
 442 static inline void dst_confirm_neigh(const struct dst_entry *dst,
 443                                      const void *daddr)
 444 {
 445         if (dst->ops->confirm_neigh)
 446                 dst->ops->confirm_neigh(dst, daddr);
 447 }
 448
 449 static inline void dst_link_failure(struct sk_buff *skb)
 450 {
 451         struct dst_entry *dst = skb_dst(skb);
 452         if (dst && dst->ops && dst->ops->link_failure)
 453                 dst->ops->link_failure(skb);
 454 }
 455
 456 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 457 {
 458         unsigned long expires = jiffies + timeout;
 459
 460         if (expires == 0)
 461                 expires = 1;
 462
 463         if (dst->expires == 0 || time_before(expires, dst->expires))
 464                 dst->expires = expires;
 465 }
 466
 467 /* Output packet to network from transport.  */
 468 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 469 {
 470         return skb_dst(skb)->output(net, sk, skb);
 471 }
 472
 473 /* Input packet from network to transport.  */
 474 static inline int dst_input(struct sk_buff *skb)
 475 {
 476         return skb_dst(skb)->input(skb);
 477 }
 478
 479 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 480 {
 481         if (dst->obsolete)
 482                 dst = dst->ops->check(dst, cookie);
 483         return dst;
 484 }
 485
 486 /* Flags for xfrm_lookup flags argument. */
 487 enum {
 488         XFRM_LOOKUP_ICMP = 1 << 0,
 489         XFRM_LOOKUP_QUEUE = 1 << 1,
 490         XFRM_LOOKUP_KEEP_DST_REF = 1 << 2,
 491 };
 492
 493 struct flowi;
 494 #ifndef CONFIG_XFRM
 495 static inline struct dst_entry *xfrm_lookup(struct net *net,
 496                                             struct dst_entry *dst_orig,
 497                                             const struct flowi *fl,
 498                                             const struct sock *sk,
 499                                             int flags)
 500 {
 501         return dst_orig;
 502 }
 503
 504 static inline struct dst_entry *xfrm_lookup_route(struct net *net,
 505                                                   struct dst_entry *dst_orig,
 506                                                   const struct flowi *fl,
 507                                                   const struct sock *sk,
 508                                                   int flags)
 509 {
 510         return dst_orig;
 511 }
 512
 513 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
 514 {
 515         return NULL;
 516 }
 517
 518 #else
 519 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
 520                               const struct flowi *fl, const struct sock *sk,
 521                               int flags);
 522
 523 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
 524                                     const struct flowi *fl, const struct sock *sk,
 525                                     int flags);
 526
 527 /* skb attached with this dst needs transformation if dst->xfrm is valid */
 528 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
 529 {
 530         return dst->xfrm;
 531 }
 532 #endif
 533
 534 static inline void skb_dst_update_pmtu(struct sk_buff *skb, u32 mtu)
 535 {
 536         struct dst_entry *dst = skb_dst(skb);
 537
 538         if (dst && dst->ops->update_pmtu)
 539                 dst->ops->update_pmtu(dst, NULL, skb, mtu, true);
 540 }
 541
 542 /* update dst pmtu but not do neighbor confirm */
 543 static inline void skb_dst_update_pmtu_no_confirm(struct sk_buff *skb, u32 mtu)
 544 {
 545         struct dst_entry *dst = skb_dst(skb);
 546
 547         if (dst && dst->ops->update_pmtu)
 548                 dst->ops->update_pmtu(dst, NULL, skb, mtu, false);
 549 }
 550
 551 #endif /* _NET_DST_H */