include/net/nexthop.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Generic nexthop implementation
   4  *
   5  * Copyright (c) 2017-19 Cumulus Networks
   6  * Copyright (c) 2017-19 David Ahern <dsa@cumulusnetworks.com>
   7  */
   8
   9 #ifndef __LINUX_NEXTHOP_H
  10 #define __LINUX_NEXTHOP_H
  11
  12 #include <linux/netdevice.h>
  13 #include <linux/notifier.h>
  14 #include <linux/route.h>
  15 #include <linux/types.h>
  16 #include <net/ip_fib.h>
  17 #include <net/ip6_fib.h>
  18 #include <net/netlink.h>
  19
  20 #define NEXTHOP_VALID_USER_FLAGS RTNH_F_ONLINK
  21
  22 struct nexthop;
  23
  24 struct nh_config {
  25         u32             nh_id;
  26
  27         u8              nh_family;
  28         u8              nh_protocol;
  29         u8              nh_blackhole;
  30         u8              nh_fdb;
  31         u32             nh_flags;
  32
  33         int             nh_ifindex;
  34         struct net_device *dev;
  35
  36         union {
  37                 __be32          ipv4;
  38                 struct in6_addr ipv6;
  39         } gw;
  40
  41         struct nlattr   *nh_grp;
  42         u16             nh_grp_type;
  43
  44         struct nlattr   *nh_encap;
  45         u16             nh_encap_type;
  46
  47         u32             nlflags;
  48         struct nl_info  nlinfo;
  49 };
  50
  51 struct nh_info {
  52         struct hlist_node       dev_hash;    /* entry on netns devhash */
  53         struct nexthop          *nh_parent;
  54
  55         u8                      family;
  56         bool                    reject_nh;
  57         bool                    fdb_nh;
  58
  59         union {
  60                 struct fib_nh_common    fib_nhc;
  61                 struct fib_nh           fib_nh;
  62                 struct fib6_nh          fib6_nh;
  63         };
  64 };
  65
  66 struct nh_grp_entry {
  67         struct nexthop  *nh;
  68         u8              weight;
  69         atomic_t        upper_bound;
  70
  71         struct list_head nh_list;
  72         struct nexthop  *nh_parent;  /* nexthop of group with this entry */
  73 };
  74
  75 struct nh_group {
  76         struct nh_group         *spare; /* spare group for removals */
  77         u16                     num_nh;
  78         bool                    mpath;
  79         bool                    fdb_nh;
  80         bool                    has_v4;
  81         struct nh_grp_entry     nh_entries[];
  82 };
  83
  84 struct nexthop {
  85         struct rb_node          rb_node;    /* entry on netns rbtree */
  86         struct list_head        fi_list;    /* v4 entries using nh */
  87         struct list_head        f6i_list;   /* v6 entries using nh */
  88         struct list_head        fdb_list;   /* fdb entries using this nh */
  89         struct list_head        grp_list;   /* nh group entries using this nh */
  90         struct net              *net;
  91
  92         u32                     id;
  93
  94         u8                      protocol;   /* app managing this nh */
  95         u8                      nh_flags;
  96         bool                    is_group;
  97
  98         refcount_t              refcnt;
  99         struct rcu_head         rcu;
 100
 101         union {
 102                 struct nh_info  __rcu *nh_info;
 103                 struct nh_group __rcu *nh_grp;
 104         };
 105 };
 106
 107 enum nexthop_event_type {
 108         NEXTHOP_EVENT_DEL,
 109         NEXTHOP_EVENT_REPLACE,
 110 };
 111
 112 struct nh_notifier_single_info {
 113         struct net_device *dev;
 114         u8 gw_family;
 115         union {
 116                 __be32 ipv4;
 117                 struct in6_addr ipv6;
 118         };
 119         u8 is_reject:1,
 120            is_fdb:1,
 121            has_encap:1;
 122 };
 123
 124 struct nh_notifier_grp_entry_info {
 125         u8 weight;
 126         u32 id;
 127         struct nh_notifier_single_info nh;
 128 };
 129
 130 struct nh_notifier_grp_info {
 131         u16 num_nh;
 132         bool is_fdb;
 133         struct nh_notifier_grp_entry_info nh_entries[];
 134 };
 135
 136 struct nh_notifier_info {
 137         struct net *net;
 138         struct netlink_ext_ack *extack;
 139         u32 id;
 140         bool is_grp;
 141         union {
 142                 struct nh_notifier_single_info *nh;
 143                 struct nh_notifier_grp_info *nh_grp;
 144         };
 145 };
 146
 147 int register_nexthop_notifier(struct net *net, struct notifier_block *nb,
 148                               struct netlink_ext_ack *extack);
 149 int unregister_nexthop_notifier(struct net *net, struct notifier_block *nb);
 150 void nexthop_set_hw_flags(struct net *net, u32 id, bool offload, bool trap);
 151
 152 /* caller is holding rcu or rtnl; no reference taken to nexthop */
 153 struct nexthop *nexthop_find_by_id(struct net *net, u32 id);
 154 void nexthop_free_rcu(struct rcu_head *head);
 155
 156 static inline bool nexthop_get(struct nexthop *nh)
 157 {
 158         return refcount_inc_not_zero(&nh->refcnt);
 159 }
 160
 161 static inline void nexthop_put(struct nexthop *nh)
 162 {
 163         if (refcount_dec_and_test(&nh->refcnt))
 164                 call_rcu(&nh->rcu, nexthop_free_rcu);
 165 }
 166
 167 static inline bool nexthop_cmp(const struct nexthop *nh1,
 168                                const struct nexthop *nh2)
 169 {
 170         return nh1 == nh2;
 171 }
 172
 173 static inline bool nexthop_is_fdb(const struct nexthop *nh)
 174 {
 175         if (nh->is_group) {
 176                 const struct nh_group *nh_grp;
 177
 178                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 179                 return nh_grp->fdb_nh;
 180         } else {
 181                 const struct nh_info *nhi;
 182
 183                 nhi = rcu_dereference_rtnl(nh->nh_info);
 184                 return nhi->fdb_nh;
 185         }
 186 }
 187
 188 static inline bool nexthop_has_v4(const struct nexthop *nh)
 189 {
 190         if (nh->is_group) {
 191                 struct nh_group *nh_grp;
 192
 193                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 194                 return nh_grp->has_v4;
 195         }
 196         return false;
 197 }
 198
 199 static inline bool nexthop_is_multipath(const struct nexthop *nh)
 200 {
 201         if (nh->is_group) {
 202                 struct nh_group *nh_grp;
 203
 204                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 205                 return nh_grp->mpath;
 206         }
 207         return false;
 208 }
 209
 210 struct nexthop *nexthop_select_path(struct nexthop *nh, int hash);
 211
 212 static inline unsigned int nexthop_num_path(const struct nexthop *nh)
 213 {
 214         unsigned int rc = 1;
 215
 216         if (nh->is_group) {
 217                 struct nh_group *nh_grp;
 218
 219                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 220                 if (nh_grp->mpath)
 221                         rc = nh_grp->num_nh;
 222         }
 223
 224         return rc;
 225 }
 226
 227 static inline
 228 struct nexthop *nexthop_mpath_select(const struct nh_group *nhg, int nhsel)
 229 {
 230         /* for_nexthops macros in fib_semantics.c grabs a pointer to
 231          * the nexthop before checking nhsel
 232          */
 233         if (nhsel >= nhg->num_nh)
 234                 return NULL;
 235
 236         return nhg->nh_entries[nhsel].nh;
 237 }
 238
 239 static inline
 240 int nexthop_mpath_fill_node(struct sk_buff *skb, struct nexthop *nh,
 241                             u8 rt_family)
 242 {
 243         struct nh_group *nhg = rtnl_dereference(nh->nh_grp);
 244         int i;
 245
 246         for (i = 0; i < nhg->num_nh; i++) {
 247                 struct nexthop *nhe = nhg->nh_entries[i].nh;
 248                 struct nh_info *nhi = rcu_dereference_rtnl(nhe->nh_info);
 249                 struct fib_nh_common *nhc = &nhi->fib_nhc;
 250                 int weight = nhg->nh_entries[i].weight;
 251
 252                 if (fib_add_nexthop(skb, nhc, weight, rt_family) < 0)
 253                         return -EMSGSIZE;
 254         }
 255
 256         return 0;
 257 }
 258
 259 /* called with rcu lock */
 260 static inline bool nexthop_is_blackhole(const struct nexthop *nh)
 261 {
 262         const struct nh_info *nhi;
 263
 264         if (nh->is_group) {
 265                 struct nh_group *nh_grp;
 266
 267                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 268                 if (nh_grp->num_nh > 1)
 269                         return false;
 270
 271                 nh = nh_grp->nh_entries[0].nh;
 272         }
 273
 274         nhi = rcu_dereference_rtnl(nh->nh_info);
 275         return nhi->reject_nh;
 276 }
 277
 278 static inline void nexthop_path_fib_result(struct fib_result *res, int hash)
 279 {
 280         struct nh_info *nhi;
 281         struct nexthop *nh;
 282
 283         nh = nexthop_select_path(res->fi->nh, hash);
 284         nhi = rcu_dereference(nh->nh_info);
 285         res->nhc = &nhi->fib_nhc;
 286 }
 287
 288 /* called with rcu read lock or rtnl held */
 289 static inline
 290 struct fib_nh_common *nexthop_fib_nhc(struct nexthop *nh, int nhsel)
 291 {
 292         struct nh_info *nhi;
 293
 294         BUILD_BUG_ON(offsetof(struct fib_nh, nh_common) != 0);
 295         BUILD_BUG_ON(offsetof(struct fib6_nh, nh_common) != 0);
 296
 297         if (nh->is_group) {
 298                 struct nh_group *nh_grp;
 299
 300                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 301                 if (nh_grp->mpath) {
 302                         nh = nexthop_mpath_select(nh_grp, nhsel);
 303                         if (!nh)
 304                                 return NULL;
 305                 }
 306         }
 307
 308         nhi = rcu_dereference_rtnl(nh->nh_info);
 309         return &nhi->fib_nhc;
 310 }
 311
 312 /* called from fib_table_lookup with rcu_lock */
 313 static inline
 314 struct fib_nh_common *nexthop_get_nhc_lookup(const struct nexthop *nh,
 315                                              int fib_flags,
 316                                              const struct flowi4 *flp,
 317                                              int *nhsel)
 318 {
 319         struct nh_info *nhi;
 320
 321         if (nh->is_group) {
 322                 struct nh_group *nhg = rcu_dereference(nh->nh_grp);
 323                 int i;
 324
 325                 for (i = 0; i < nhg->num_nh; i++) {
 326                         struct nexthop *nhe = nhg->nh_entries[i].nh;
 327
 328                         nhi = rcu_dereference(nhe->nh_info);
 329                         if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
 330                                 *nhsel = i;
 331                                 return &nhi->fib_nhc;
 332                         }
 333                 }
 334         } else {
 335                 nhi = rcu_dereference(nh->nh_info);
 336                 if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
 337                         *nhsel = 0;
 338                         return &nhi->fib_nhc;
 339                 }
 340         }
 341
 342         return NULL;
 343 }
 344
 345 static inline bool nexthop_uses_dev(const struct nexthop *nh,
 346                                     const struct net_device *dev)
 347 {
 348         struct nh_info *nhi;
 349
 350         if (nh->is_group) {
 351                 struct nh_group *nhg = rcu_dereference(nh->nh_grp);
 352                 int i;
 353
 354                 for (i = 0; i < nhg->num_nh; i++) {
 355                         struct nexthop *nhe = nhg->nh_entries[i].nh;
 356
 357                         nhi = rcu_dereference(nhe->nh_info);
 358                         if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
 359                                 return true;
 360                 }
 361         } else {
 362                 nhi = rcu_dereference(nh->nh_info);
 363                 if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
 364                         return true;
 365         }
 366
 367         return false;
 368 }
 369
 370 static inline unsigned int fib_info_num_path(const struct fib_info *fi)
 371 {
 372         if (unlikely(fi->nh))
 373                 return nexthop_num_path(fi->nh);
 374
 375         return fi->fib_nhs;
 376 }
 377
 378 int fib_check_nexthop(struct nexthop *nh, u8 scope,
 379                       struct netlink_ext_ack *extack);
 380
 381 static inline struct fib_nh_common *fib_info_nhc(struct fib_info *fi, int nhsel)
 382 {
 383         if (unlikely(fi->nh))
 384                 return nexthop_fib_nhc(fi->nh, nhsel);
 385
 386         return &fi->fib_nh[nhsel].nh_common;
 387 }
 388
 389 /* only used when fib_nh is built into fib_info */
 390 static inline struct fib_nh *fib_info_nh(struct fib_info *fi, int nhsel)
 391 {
 392         WARN_ON(fi->nh);
 393
 394         return &fi->fib_nh[nhsel];
 395 }
 396
 397 /*
 398  * IPv6 variants
 399  */
 400 int fib6_check_nexthop(struct nexthop *nh, struct fib6_config *cfg,
 401                        struct netlink_ext_ack *extack);
 402
 403 static inline struct fib6_nh *nexthop_fib6_nh(struct nexthop *nh)
 404 {
 405         struct nh_info *nhi;
 406
 407         if (nh->is_group) {
 408                 struct nh_group *nh_grp;
 409
 410                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 411                 nh = nexthop_mpath_select(nh_grp, 0);
 412                 if (!nh)
 413                         return NULL;
 414         }
 415
 416         nhi = rcu_dereference_rtnl(nh->nh_info);
 417         if (nhi->family == AF_INET6)
 418                 return &nhi->fib6_nh;
 419
 420         return NULL;
 421 }
 422
 423 static inline struct net_device *fib6_info_nh_dev(struct fib6_info *f6i)
 424 {
 425         struct fib6_nh *fib6_nh;
 426
 427         fib6_nh = f6i->nh ? nexthop_fib6_nh(f6i->nh) : f6i->fib6_nh;
 428         return fib6_nh->fib_nh_dev;
 429 }
 430
 431 static inline void nexthop_path_fib6_result(struct fib6_result *res, int hash)
 432 {
 433         struct nexthop *nh = res->f6i->nh;
 434         struct nh_info *nhi;
 435
 436         nh = nexthop_select_path(nh, hash);
 437
 438         nhi = rcu_dereference_rtnl(nh->nh_info);
 439         if (nhi->reject_nh) {
 440                 res->fib6_type = RTN_BLACKHOLE;
 441                 res->fib6_flags |= RTF_REJECT;
 442                 res->nh = nexthop_fib6_nh(nh);
 443         } else {
 444                 res->nh = &nhi->fib6_nh;
 445         }
 446 }
 447
 448 int nexthop_for_each_fib6_nh(struct nexthop *nh,
 449                              int (*cb)(struct fib6_nh *nh, void *arg),
 450                              void *arg);
 451
 452 static inline int nexthop_get_family(struct nexthop *nh)
 453 {
 454         struct nh_info *nhi = rcu_dereference_rtnl(nh->nh_info);
 455
 456         return nhi->family;
 457 }
 458
 459 static inline
 460 struct fib_nh_common *nexthop_fdb_nhc(struct nexthop *nh)
 461 {
 462         struct nh_info *nhi = rcu_dereference_rtnl(nh->nh_info);
 463
 464         return &nhi->fib_nhc;
 465 }
 466
 467 static inline struct fib_nh_common *nexthop_path_fdb_result(struct nexthop *nh,
 468                                                             int hash)
 469 {
 470         struct nh_info *nhi;
 471         struct nexthop *nhp;
 472
 473         nhp = nexthop_select_path(nh, hash);
 474         if (unlikely(!nhp))
 475                 return NULL;
 476         nhi = rcu_dereference(nhp->nh_info);
 477         return &nhi->fib_nhc;
 478 }
 479 #endif