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  dst_ops         *ops;
  38         unsigned long           _metrics;
  39         unsigned long           expires;
  40 #ifdef CONFIG_XFRM
  41         struct xfrm_state       *xfrm;
  42 #else
  43         void                    *__pad1;
  44 #endif
  45         int                     (*input)(struct sk_buff *);
  46         int                     (*output)(struct net *net, struct sock *sk, struct sk_buff *skb);
  47
  48         unsigned short          flags;
  49 #define DST_HOST                0x0001
  50 #define DST_NOXFRM              0x0002
  51 #define DST_NOPOLICY            0x0004
  52 #define DST_NOCOUNT             0x0008
  53 #define DST_FAKE_RTABLE         0x0010
  54 #define DST_XFRM_TUNNEL         0x0020
  55 #define DST_XFRM_QUEUE          0x0040
  56 #define DST_METADATA            0x0080
  57
  58         /* A non-zero value of dst->obsolete forces by-hand validation
  59          * of the route entry.  Positive values are set by the generic
  60          * dst layer to indicate that the entry has been forcefully
  61          * destroyed.
  62          *
  63          * Negative values are used by the implementation layer code to
  64          * force invocation of the dst_ops->check() method.
  65          */
  66         short                   obsolete;
  67 #define DST_OBSOLETE_NONE       0
  68 #define DST_OBSOLETE_DEAD       2
  69 #define DST_OBSOLETE_FORCE_CHK  -1
  70 #define DST_OBSOLETE_KILL       -2
  71         unsigned short          header_len;     /* more space at head required */
  72         unsigned short          trailer_len;    /* space to reserve at tail */
  73
  74         /*
  75          * __refcnt wants to be on a different cache line from
  76          * input/output/ops or performance tanks badly
  77          */
  78 #ifdef CONFIG_64BIT
  79         atomic_t                __refcnt;       /* 64-bit offset 64 */
  80 #endif
  81         int                     __use;
  82         unsigned long           lastuse;
  83         struct lwtunnel_state   *lwtstate;
  84         struct rcu_head         rcu_head;
  85         short                   error;
  86         short                   __pad;
  87         __u32                   tclassid;
  88 #ifndef CONFIG_64BIT
  89         atomic_t                __refcnt;       /* 32-bit offset 64 */
  90 #endif
  91 };
  92
  93 struct dst_metrics {
  94         u32             metrics[RTAX_MAX];
  95         refcount_t      refcnt;
  96 };
  97 extern const struct dst_metrics dst_default_metrics;
  98
  99 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
 100
 101 #define DST_METRICS_READ_ONLY           0x1UL
 102 #define DST_METRICS_REFCOUNTED          0x2UL
 103 #define DST_METRICS_FLAGS               0x3UL
 104 #define __DST_METRICS_PTR(Y)    \
 105         ((u32 *)((Y) & ~DST_METRICS_FLAGS))
 106 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
 107
 108 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
 109 {
 110         return dst->_metrics & DST_METRICS_READ_ONLY;
 111 }
 112
 113 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
 114
 115 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
 116 {
 117         unsigned long val = dst->_metrics;
 118         if (!(val & DST_METRICS_READ_ONLY))
 119                 __dst_destroy_metrics_generic(dst, val);
 120 }
 121
 122 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
 123 {
 124         unsigned long p = dst->_metrics;
 125
 126         BUG_ON(!p);
 127
 128         if (p & DST_METRICS_READ_ONLY)
 129                 return dst->ops->cow_metrics(dst, p);
 130         return __DST_METRICS_PTR(p);
 131 }
 132
 133 /* This may only be invoked before the entry has reached global
 134  * visibility.
 135  */
 136 static inline void dst_init_metrics(struct dst_entry *dst,
 137                                     const u32 *src_metrics,
 138                                     bool read_only)
 139 {
 140         dst->_metrics = ((unsigned long) src_metrics) |
 141                 (read_only ? DST_METRICS_READ_ONLY : 0);
 142 }
 143
 144 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
 145 {
 146         u32 *dst_metrics = dst_metrics_write_ptr(dest);
 147
 148         if (dst_metrics) {
 149                 u32 *src_metrics = DST_METRICS_PTR(src);
 150
 151                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
 152         }
 153 }
 154
 155 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
 156 {
 157         return DST_METRICS_PTR(dst);
 158 }
 159
 160 static inline u32
 161 dst_metric_raw(const struct dst_entry *dst, const int metric)
 162 {
 163         u32 *p = DST_METRICS_PTR(dst);
 164
 165         return p[metric-1];
 166 }
 167
 168 static inline u32
 169 dst_metric(const struct dst_entry *dst, const int metric)
 170 {
 171         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
 172                      metric == RTAX_ADVMSS ||
 173                      metric == RTAX_MTU);
 174         return dst_metric_raw(dst, metric);
 175 }
 176
 177 static inline u32
 178 dst_metric_advmss(const struct dst_entry *dst)
 179 {
 180         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
 181
 182         if (!advmss)
 183                 advmss = dst->ops->default_advmss(dst);
 184
 185         return advmss;
 186 }
 187
 188 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
 189 {
 190         u32 *p = dst_metrics_write_ptr(dst);
 191
 192         if (p)
 193                 p[metric-1] = val;
 194 }
 195
 196 /* Kernel-internal feature bits that are unallocated in user space. */
 197 #define DST_FEATURE_ECN_CA      (1 << 31)
 198
 199 #define DST_FEATURE_MASK        (DST_FEATURE_ECN_CA)
 200 #define DST_FEATURE_ECN_MASK    (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN)
 201
 202 static inline u32
 203 dst_feature(const struct dst_entry *dst, u32 feature)
 204 {
 205         return dst_metric(dst, RTAX_FEATURES) & feature;
 206 }
 207
 208 static inline u32 dst_mtu(const struct dst_entry *dst)
 209 {
 210         return dst->ops->mtu(dst);
 211 }
 212
 213 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 214 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 215 {
 216         return msecs_to_jiffies(dst_metric(dst, metric));
 217 }
 218
 219 static inline u32
 220 dst_allfrag(const struct dst_entry *dst)
 221 {
 222         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
 223         return ret;
 224 }
 225
 226 static inline int
 227 dst_metric_locked(const struct dst_entry *dst, int metric)
 228 {
 229         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 230 }
 231
 232 static inline void dst_hold(struct dst_entry *dst)
 233 {
 234         /*
 235          * If your kernel compilation stops here, please check
 236          * the placement of __refcnt in struct dst_entry
 237          */
 238         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 239         WARN_ON(atomic_inc_not_zero(&dst->__refcnt) == 0);
 240 }
 241
 242 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
 243 {
 244         if (unlikely(time != dst->lastuse)) {
 245                 dst->__use++;
 246                 dst->lastuse = time;
 247         }
 248 }
 249
 250 static inline void dst_hold_and_use(struct dst_entry *dst, unsigned long time)
 251 {
 252         dst_hold(dst);
 253         dst_use_noref(dst, time);
 254 }
 255
 256 static inline struct dst_entry *dst_clone(struct dst_entry *dst)
 257 {
 258         if (dst)
 259                 dst_hold(dst);
 260         return dst;
 261 }
 262
 263 void dst_release(struct dst_entry *dst);
 264
 265 void dst_release_immediate(struct dst_entry *dst);
 266
 267 static inline void refdst_drop(unsigned long refdst)
 268 {
 269         if (!(refdst & SKB_DST_NOREF))
 270                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 271 }
 272
 273 /**
 274  * skb_dst_drop - drops skb dst
 275  * @skb: buffer
 276  *
 277  * Drops dst reference count if a reference was taken.
 278  */
 279 static inline void skb_dst_drop(struct sk_buff *skb)
 280 {
 281         if (skb->_skb_refdst) {
 282                 refdst_drop(skb->_skb_refdst);
 283                 skb->_skb_refdst = 0UL;
 284         }
 285 }
 286
 287 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst)
 288 {
 289         nskb->_skb_refdst = refdst;
 290         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 291                 dst_clone(skb_dst(nskb));
 292 }
 293
 294 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 295 {
 296         __skb_dst_copy(nskb, oskb->_skb_refdst);
 297 }
 298
 299 /**
 300  * dst_hold_safe - Take a reference on a dst if possible
 301  * @dst: pointer to dst entry
 302  *
 303  * This helper returns false if it could not safely
 304  * take a reference on a dst.
 305  */
 306 static inline bool dst_hold_safe(struct dst_entry *dst)
 307 {
 308         return atomic_inc_not_zero(&dst->__refcnt);
 309 }
 310
 311 /**
 312  * skb_dst_force - makes sure skb dst is refcounted
 313  * @skb: buffer
 314  *
 315  * If dst is not yet refcounted and not destroyed, grab a ref on it.
 316  */
 317 static inline void skb_dst_force(struct sk_buff *skb)
 318 {
 319         if (skb_dst_is_noref(skb)) {
 320                 struct dst_entry *dst = skb_dst(skb);
 321
 322                 WARN_ON(!rcu_read_lock_held());
 323                 if (!dst_hold_safe(dst))
 324                         dst = NULL;
 325
 326                 skb->_skb_refdst = (unsigned long)dst;
 327         }
 328 }
 329
 330
 331 /**
 332  *      __skb_tunnel_rx - prepare skb for rx reinsert
 333  *      @skb: buffer
 334  *      @dev: tunnel device
 335  *      @net: netns for packet i/o
 336  *
 337  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 338  *      so make some cleanups. (no accounting done)
 339  */
 340 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 341                                    struct net *net)
 342 {
 343         skb->dev = dev;
 344
 345         /*
 346          * Clear hash so that we can recalulate the hash for the
 347          * encapsulated packet, unless we have already determine the hash
 348          * over the L4 4-tuple.
 349          */
 350         skb_clear_hash_if_not_l4(skb);
 351         skb_set_queue_mapping(skb, 0);
 352         skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
 353 }
 354
 355 /**
 356  *      skb_tunnel_rx - prepare skb for rx reinsert
 357  *      @skb: buffer
 358  *      @dev: tunnel device
 359  *      @net: netns for packet i/o
 360  *
 361  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 362  *      so make some cleanups, and perform accounting.
 363  *      Note: this accounting is not SMP safe.
 364  */
 365 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
 366                                  struct net *net)
 367 {
 368         /* TODO : stats should be SMP safe */
 369         dev->stats.rx_packets++;
 370         dev->stats.rx_bytes += skb->len;
 371         __skb_tunnel_rx(skb, dev, net);
 372 }
 373
 374 static inline u32 dst_tclassid(const struct sk_buff *skb)
 375 {
 376 #ifdef CONFIG_IP_ROUTE_CLASSID
 377         const struct dst_entry *dst;
 378
 379         dst = skb_dst(skb);
 380         if (dst)
 381                 return dst->tclassid;
 382 #endif
 383         return 0;
 384 }
 385
 386 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
 387 static inline int dst_discard(struct sk_buff *skb)
 388 {
 389         return dst_discard_out(&init_net, skb->sk, skb);
 390 }
 391 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref,
 392                 int initial_obsolete, unsigned short flags);
 393 void dst_init(struct dst_entry *dst, struct dst_ops *ops,
 394               struct net_device *dev, int initial_ref, int initial_obsolete,
 395               unsigned short flags);
 396 struct dst_entry *dst_destroy(struct dst_entry *dst);
 397 void dst_dev_put(struct dst_entry *dst);
 398
 399 static inline void dst_confirm(struct dst_entry *dst)
 400 {
 401 }
 402
 403 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
 404 {
 405         struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
 406         return IS_ERR(n) ? NULL : n;
 407 }
 408
 409 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
 410                                                      struct sk_buff *skb)
 411 {
 412         struct neighbour *n =  dst->ops->neigh_lookup(dst, skb, NULL);
 413         return IS_ERR(n) ? NULL : n;
 414 }
 415
 416 static inline void dst_confirm_neigh(const struct dst_entry *dst,
 417                                      const void *daddr)
 418 {
 419         if (dst->ops->confirm_neigh)
 420                 dst->ops->confirm_neigh(dst, daddr);
 421 }
 422
 423 static inline void dst_link_failure(struct sk_buff *skb)
 424 {
 425         struct dst_entry *dst = skb_dst(skb);
 426         if (dst && dst->ops && dst->ops->link_failure)
 427                 dst->ops->link_failure(skb);
 428 }
 429
 430 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 431 {
 432         unsigned long expires = jiffies + timeout;
 433
 434         if (expires == 0)
 435                 expires = 1;
 436
 437         if (dst->expires == 0 || time_before(expires, dst->expires))
 438                 dst->expires = expires;
 439 }
 440
 441 /* Output packet to network from transport.  */
 442 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 443 {
 444         return skb_dst(skb)->output(net, sk, skb);
 445 }
 446
 447 /* Input packet from network to transport.  */
 448 static inline int dst_input(struct sk_buff *skb)
 449 {
 450         return skb_dst(skb)->input(skb);
 451 }
 452
 453 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 454 {
 455         if (dst->obsolete)
 456                 dst = dst->ops->check(dst, cookie);
 457         return dst;
 458 }
 459
 460 /* Flags for xfrm_lookup flags argument. */
 461 enum {
 462         XFRM_LOOKUP_ICMP = 1 << 0,
 463         XFRM_LOOKUP_QUEUE = 1 << 1,
 464         XFRM_LOOKUP_KEEP_DST_REF = 1 << 2,
 465 };
 466
 467 struct flowi;
 468 #ifndef CONFIG_XFRM
 469 static inline struct dst_entry *xfrm_lookup(struct net *net,
 470                                             struct dst_entry *dst_orig,
 471                                             const struct flowi *fl,
 472                                             const struct sock *sk,
 473                                             int flags)
 474 {
 475         return dst_orig;
 476 }
 477
 478 static inline struct dst_entry *
 479 xfrm_lookup_with_ifid(struct net *net, struct dst_entry *dst_orig,
 480                       const struct flowi *fl, const struct sock *sk,
 481                       int flags, u32 if_id)
 482 {
 483         return dst_orig;
 484 }
 485
 486 static inline struct dst_entry *xfrm_lookup_route(struct net *net,
 487                                                   struct dst_entry *dst_orig,
 488                                                   const struct flowi *fl,
 489                                                   const struct sock *sk,
 490                                                   int flags)
 491 {
 492         return dst_orig;
 493 }
 494
 495 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
 496 {
 497         return NULL;
 498 }
 499
 500 #else
 501 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
 502                               const struct flowi *fl, const struct sock *sk,
 503                               int flags);
 504
 505 struct dst_entry *xfrm_lookup_with_ifid(struct net *net,
 506                                         struct dst_entry *dst_orig,
 507                                         const struct flowi *fl,
 508                                         const struct sock *sk, int flags,
 509                                         u32 if_id);
 510
 511 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
 512                                     const struct flowi *fl, const struct sock *sk,
 513                                     int flags);
 514
 515 /* skb attached with this dst needs transformation if dst->xfrm is valid */
 516 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
 517 {
 518         return dst->xfrm;
 519 }
 520 #endif
 521
 522 static inline void skb_dst_update_pmtu(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);
 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(skb, encap_mtu - headroom);
 538 }
 539
 540 #endif /* _NET_DST_H */