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 };
 110
 111 int register_nexthop_notifier(struct net *net, struct notifier_block *nb);
 112 int unregister_nexthop_notifier(struct net *net, struct notifier_block *nb);
 113
 114 /* caller is holding rcu or rtnl; no reference taken to nexthop */
 115 struct nexthop *nexthop_find_by_id(struct net *net, u32 id);
 116 void nexthop_free_rcu(struct rcu_head *head);
 117
 118 static inline bool nexthop_get(struct nexthop *nh)
 119 {
 120         return refcount_inc_not_zero(&nh->refcnt);
 121 }
 122
 123 static inline void nexthop_put(struct nexthop *nh)
 124 {
 125         if (refcount_dec_and_test(&nh->refcnt))
 126                 call_rcu(&nh->rcu, nexthop_free_rcu);
 127 }
 128
 129 static inline bool nexthop_cmp(const struct nexthop *nh1,
 130                                const struct nexthop *nh2)
 131 {
 132         return nh1 == nh2;
 133 }
 134
 135 static inline bool nexthop_is_fdb(const struct nexthop *nh)
 136 {
 137         if (nh->is_group) {
 138                 const struct nh_group *nh_grp;
 139
 140                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 141                 return nh_grp->fdb_nh;
 142         } else {
 143                 const struct nh_info *nhi;
 144
 145                 nhi = rcu_dereference_rtnl(nh->nh_info);
 146                 return nhi->fdb_nh;
 147         }
 148 }
 149
 150 static inline bool nexthop_has_v4(const struct nexthop *nh)
 151 {
 152         if (nh->is_group) {
 153                 struct nh_group *nh_grp;
 154
 155                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 156                 return nh_grp->has_v4;
 157         }
 158         return false;
 159 }
 160
 161 static inline bool nexthop_is_multipath(const struct nexthop *nh)
 162 {
 163         if (nh->is_group) {
 164                 struct nh_group *nh_grp;
 165
 166                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 167                 return nh_grp->mpath;
 168         }
 169         return false;
 170 }
 171
 172 struct nexthop *nexthop_select_path(struct nexthop *nh, int hash);
 173
 174 static inline unsigned int nexthop_num_path(const struct nexthop *nh)
 175 {
 176         unsigned int rc = 1;
 177
 178         if (nh->is_group) {
 179                 struct nh_group *nh_grp;
 180
 181                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 182                 if (nh_grp->mpath)
 183                         rc = nh_grp->num_nh;
 184         }
 185
 186         return rc;
 187 }
 188
 189 static inline
 190 struct nexthop *nexthop_mpath_select(const struct nh_group *nhg, int nhsel)
 191 {
 192         /* for_nexthops macros in fib_semantics.c grabs a pointer to
 193          * the nexthop before checking nhsel
 194          */
 195         if (nhsel >= nhg->num_nh)
 196                 return NULL;
 197
 198         return nhg->nh_entries[nhsel].nh;
 199 }
 200
 201 static inline
 202 int nexthop_mpath_fill_node(struct sk_buff *skb, struct nexthop *nh,
 203                             u8 rt_family)
 204 {
 205         struct nh_group *nhg = rtnl_dereference(nh->nh_grp);
 206         int i;
 207
 208         for (i = 0; i < nhg->num_nh; i++) {
 209                 struct nexthop *nhe = nhg->nh_entries[i].nh;
 210                 struct nh_info *nhi = rcu_dereference_rtnl(nhe->nh_info);
 211                 struct fib_nh_common *nhc = &nhi->fib_nhc;
 212                 int weight = nhg->nh_entries[i].weight;
 213
 214                 if (fib_add_nexthop(skb, nhc, weight, rt_family) < 0)
 215                         return -EMSGSIZE;
 216         }
 217
 218         return 0;
 219 }
 220
 221 /* called with rcu lock */
 222 static inline bool nexthop_is_blackhole(const struct nexthop *nh)
 223 {
 224         const struct nh_info *nhi;
 225
 226         if (nh->is_group) {
 227                 struct nh_group *nh_grp;
 228
 229                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 230                 if (nh_grp->num_nh > 1)
 231                         return false;
 232
 233                 nh = nh_grp->nh_entries[0].nh;
 234         }
 235
 236         nhi = rcu_dereference_rtnl(nh->nh_info);
 237         return nhi->reject_nh;
 238 }
 239
 240 static inline void nexthop_path_fib_result(struct fib_result *res, int hash)
 241 {
 242         struct nh_info *nhi;
 243         struct nexthop *nh;
 244
 245         nh = nexthop_select_path(res->fi->nh, hash);
 246         nhi = rcu_dereference(nh->nh_info);
 247         res->nhc = &nhi->fib_nhc;
 248 }
 249
 250 /* called with rcu read lock or rtnl held */
 251 static inline
 252 struct fib_nh_common *nexthop_fib_nhc(struct nexthop *nh, int nhsel)
 253 {
 254         struct nh_info *nhi;
 255
 256         BUILD_BUG_ON(offsetof(struct fib_nh, nh_common) != 0);
 257         BUILD_BUG_ON(offsetof(struct fib6_nh, nh_common) != 0);
 258
 259         if (nh->is_group) {
 260                 struct nh_group *nh_grp;
 261
 262                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 263                 if (nh_grp->mpath) {
 264                         nh = nexthop_mpath_select(nh_grp, nhsel);
 265                         if (!nh)
 266                                 return NULL;
 267                 }
 268         }
 269
 270         nhi = rcu_dereference_rtnl(nh->nh_info);
 271         return &nhi->fib_nhc;
 272 }
 273
 274 /* called from fib_table_lookup with rcu_lock */
 275 static inline
 276 struct fib_nh_common *nexthop_get_nhc_lookup(const struct nexthop *nh,
 277                                              int fib_flags,
 278                                              const struct flowi4 *flp,
 279                                              int *nhsel)
 280 {
 281         struct nh_info *nhi;
 282
 283         if (nh->is_group) {
 284                 struct nh_group *nhg = rcu_dereference(nh->nh_grp);
 285                 int i;
 286
 287                 for (i = 0; i < nhg->num_nh; i++) {
 288                         struct nexthop *nhe = nhg->nh_entries[i].nh;
 289
 290                         nhi = rcu_dereference(nhe->nh_info);
 291                         if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
 292                                 *nhsel = i;
 293                                 return &nhi->fib_nhc;
 294                         }
 295                 }
 296         } else {
 297                 nhi = rcu_dereference(nh->nh_info);
 298                 if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
 299                         *nhsel = 0;
 300                         return &nhi->fib_nhc;
 301                 }
 302         }
 303
 304         return NULL;
 305 }
 306
 307 static inline bool nexthop_uses_dev(const struct nexthop *nh,
 308                                     const struct net_device *dev)
 309 {
 310         struct nh_info *nhi;
 311
 312         if (nh->is_group) {
 313                 struct nh_group *nhg = rcu_dereference(nh->nh_grp);
 314                 int i;
 315
 316                 for (i = 0; i < nhg->num_nh; i++) {
 317                         struct nexthop *nhe = nhg->nh_entries[i].nh;
 318
 319                         nhi = rcu_dereference(nhe->nh_info);
 320                         if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
 321                                 return true;
 322                 }
 323         } else {
 324                 nhi = rcu_dereference(nh->nh_info);
 325                 if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
 326                         return true;
 327         }
 328
 329         return false;
 330 }
 331
 332 static inline unsigned int fib_info_num_path(const struct fib_info *fi)
 333 {
 334         if (unlikely(fi->nh))
 335                 return nexthop_num_path(fi->nh);
 336
 337         return fi->fib_nhs;
 338 }
 339
 340 int fib_check_nexthop(struct nexthop *nh, u8 scope,
 341                       struct netlink_ext_ack *extack);
 342
 343 static inline struct fib_nh_common *fib_info_nhc(struct fib_info *fi, int nhsel)
 344 {
 345         if (unlikely(fi->nh))
 346                 return nexthop_fib_nhc(fi->nh, nhsel);
 347
 348         return &fi->fib_nh[nhsel].nh_common;
 349 }
 350
 351 /* only used when fib_nh is built into fib_info */
 352 static inline struct fib_nh *fib_info_nh(struct fib_info *fi, int nhsel)
 353 {
 354         WARN_ON(fi->nh);
 355
 356         return &fi->fib_nh[nhsel];
 357 }
 358
 359 /*
 360  * IPv6 variants
 361  */
 362 int fib6_check_nexthop(struct nexthop *nh, struct fib6_config *cfg,
 363                        struct netlink_ext_ack *extack);
 364
 365 static inline struct fib6_nh *nexthop_fib6_nh(struct nexthop *nh)
 366 {
 367         struct nh_info *nhi;
 368
 369         if (nh->is_group) {
 370                 struct nh_group *nh_grp;
 371
 372                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 373                 nh = nexthop_mpath_select(nh_grp, 0);
 374                 if (!nh)
 375                         return NULL;
 376         }
 377
 378         nhi = rcu_dereference_rtnl(nh->nh_info);
 379         if (nhi->family == AF_INET6)
 380                 return &nhi->fib6_nh;
 381
 382         return NULL;
 383 }
 384
 385 static inline struct net_device *fib6_info_nh_dev(struct fib6_info *f6i)
 386 {
 387         struct fib6_nh *fib6_nh;
 388
 389         fib6_nh = f6i->nh ? nexthop_fib6_nh(f6i->nh) : f6i->fib6_nh;
 390         return fib6_nh->fib_nh_dev;
 391 }
 392
 393 static inline void nexthop_path_fib6_result(struct fib6_result *res, int hash)
 394 {
 395         struct nexthop *nh = res->f6i->nh;
 396         struct nh_info *nhi;
 397
 398         nh = nexthop_select_path(nh, hash);
 399
 400         nhi = rcu_dereference_rtnl(nh->nh_info);
 401         if (nhi->reject_nh) {
 402                 res->fib6_type = RTN_BLACKHOLE;
 403                 res->fib6_flags |= RTF_REJECT;
 404                 res->nh = nexthop_fib6_nh(nh);
 405         } else {
 406                 res->nh = &nhi->fib6_nh;
 407         }
 408 }
 409
 410 int nexthop_for_each_fib6_nh(struct nexthop *nh,
 411                              int (*cb)(struct fib6_nh *nh, void *arg),
 412                              void *arg);
 413
 414 static inline int nexthop_get_family(struct nexthop *nh)
 415 {
 416         struct nh_info *nhi = rcu_dereference_rtnl(nh->nh_info);
 417
 418         return nhi->family;
 419 }
 420
 421 static inline
 422 struct fib_nh_common *nexthop_fdb_nhc(struct nexthop *nh)
 423 {
 424         struct nh_info *nhi = rcu_dereference_rtnl(nh->nh_info);
 425
 426         return &nhi->fib_nhc;
 427 }
 428
 429 static inline struct fib_nh_common *nexthop_path_fdb_result(struct nexthop *nh,
 430                                                             int hash)
 431 {
 432         struct nh_info *nhi;
 433         struct nexthop *nhp;
 434
 435         nhp = nexthop_select_path(nh, hash);
 436         if (unlikely(!nhp))
 437                 return NULL;
 438         nhi = rcu_dereference(nhp->nh_info);
 439         return &nhi->fib_nhc;
 440 }
 441 #endif