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_ADD,
 109         NEXTHOP_EVENT_DEL
 110 };
 111
 112 int call_nexthop_notifier(struct notifier_block *nb, struct net *net,
 113                           enum nexthop_event_type event_type,
 114                           struct nexthop *nh);
 115 int register_nexthop_notifier(struct net *net, struct notifier_block *nb);
 116 int unregister_nexthop_notifier(struct net *net, struct notifier_block *nb);
 117
 118 /* caller is holding rcu or rtnl; no reference taken to nexthop */
 119 struct nexthop *nexthop_find_by_id(struct net *net, u32 id);
 120 void nexthop_free_rcu(struct rcu_head *head);
 121
 122 static inline bool nexthop_get(struct nexthop *nh)
 123 {
 124         return refcount_inc_not_zero(&nh->refcnt);
 125 }
 126
 127 static inline void nexthop_put(struct nexthop *nh)
 128 {
 129         if (refcount_dec_and_test(&nh->refcnt))
 130                 call_rcu(&nh->rcu, nexthop_free_rcu);
 131 }
 132
 133 static inline bool nexthop_cmp(const struct nexthop *nh1,
 134                                const struct nexthop *nh2)
 135 {
 136         return nh1 == nh2;
 137 }
 138
 139 static inline bool nexthop_is_fdb(const struct nexthop *nh)
 140 {
 141         if (nh->is_group) {
 142                 const struct nh_group *nh_grp;
 143
 144                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 145                 return nh_grp->fdb_nh;
 146         } else {
 147                 const struct nh_info *nhi;
 148
 149                 nhi = rcu_dereference_rtnl(nh->nh_info);
 150                 return nhi->fdb_nh;
 151         }
 152 }
 153
 154 static inline bool nexthop_has_v4(const struct nexthop *nh)
 155 {
 156         if (nh->is_group) {
 157                 struct nh_group *nh_grp;
 158
 159                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 160                 return nh_grp->has_v4;
 161         }
 162         return false;
 163 }
 164
 165 static inline bool nexthop_is_multipath(const struct nexthop *nh)
 166 {
 167         if (nh->is_group) {
 168                 struct nh_group *nh_grp;
 169
 170                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 171                 return nh_grp->mpath;
 172         }
 173         return false;
 174 }
 175
 176 struct nexthop *nexthop_select_path(struct nexthop *nh, int hash);
 177
 178 static inline unsigned int nexthop_num_path(const struct nexthop *nh)
 179 {
 180         unsigned int rc = 1;
 181
 182         if (nh->is_group) {
 183                 struct nh_group *nh_grp;
 184
 185                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 186                 if (nh_grp->mpath)
 187                         rc = nh_grp->num_nh;
 188         }
 189
 190         return rc;
 191 }
 192
 193 static inline
 194 struct nexthop *nexthop_mpath_select(const struct nh_group *nhg, int nhsel)
 195 {
 196         /* for_nexthops macros in fib_semantics.c grabs a pointer to
 197          * the nexthop before checking nhsel
 198          */
 199         if (nhsel >= nhg->num_nh)
 200                 return NULL;
 201
 202         return nhg->nh_entries[nhsel].nh;
 203 }
 204
 205 static inline
 206 int nexthop_mpath_fill_node(struct sk_buff *skb, struct nexthop *nh,
 207                             u8 rt_family)
 208 {
 209         struct nh_group *nhg = rtnl_dereference(nh->nh_grp);
 210         int i;
 211
 212         for (i = 0; i < nhg->num_nh; i++) {
 213                 struct nexthop *nhe = nhg->nh_entries[i].nh;
 214                 struct nh_info *nhi = rcu_dereference_rtnl(nhe->nh_info);
 215                 struct fib_nh_common *nhc = &nhi->fib_nhc;
 216                 int weight = nhg->nh_entries[i].weight;
 217
 218                 if (fib_add_nexthop(skb, nhc, weight, rt_family) < 0)
 219                         return -EMSGSIZE;
 220         }
 221
 222         return 0;
 223 }
 224
 225 /* called with rcu lock */
 226 static inline bool nexthop_is_blackhole(const struct nexthop *nh)
 227 {
 228         const struct nh_info *nhi;
 229
 230         if (nh->is_group) {
 231                 struct nh_group *nh_grp;
 232
 233                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 234                 if (nh_grp->num_nh > 1)
 235                         return false;
 236
 237                 nh = nh_grp->nh_entries[0].nh;
 238         }
 239
 240         nhi = rcu_dereference_rtnl(nh->nh_info);
 241         return nhi->reject_nh;
 242 }
 243
 244 static inline void nexthop_path_fib_result(struct fib_result *res, int hash)
 245 {
 246         struct nh_info *nhi;
 247         struct nexthop *nh;
 248
 249         nh = nexthop_select_path(res->fi->nh, hash);
 250         nhi = rcu_dereference(nh->nh_info);
 251         res->nhc = &nhi->fib_nhc;
 252 }
 253
 254 /* called with rcu read lock or rtnl held */
 255 static inline
 256 struct fib_nh_common *nexthop_fib_nhc(struct nexthop *nh, int nhsel)
 257 {
 258         struct nh_info *nhi;
 259
 260         BUILD_BUG_ON(offsetof(struct fib_nh, nh_common) != 0);
 261         BUILD_BUG_ON(offsetof(struct fib6_nh, nh_common) != 0);
 262
 263         if (nh->is_group) {
 264                 struct nh_group *nh_grp;
 265
 266                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 267                 if (nh_grp->mpath) {
 268                         nh = nexthop_mpath_select(nh_grp, nhsel);
 269                         if (!nh)
 270                                 return NULL;
 271                 }
 272         }
 273
 274         nhi = rcu_dereference_rtnl(nh->nh_info);
 275         return &nhi->fib_nhc;
 276 }
 277
 278 /* called from fib_table_lookup with rcu_lock */
 279 static inline
 280 struct fib_nh_common *nexthop_get_nhc_lookup(const struct nexthop *nh,
 281                                              int fib_flags,
 282                                              const struct flowi4 *flp,
 283                                              int *nhsel)
 284 {
 285         struct nh_info *nhi;
 286
 287         if (nh->is_group) {
 288                 struct nh_group *nhg = rcu_dereference(nh->nh_grp);
 289                 int i;
 290
 291                 for (i = 0; i < nhg->num_nh; i++) {
 292                         struct nexthop *nhe = nhg->nh_entries[i].nh;
 293
 294                         nhi = rcu_dereference(nhe->nh_info);
 295                         if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
 296                                 *nhsel = i;
 297                                 return &nhi->fib_nhc;
 298                         }
 299                 }
 300         } else {
 301                 nhi = rcu_dereference(nh->nh_info);
 302                 if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
 303                         *nhsel = 0;
 304                         return &nhi->fib_nhc;
 305                 }
 306         }
 307
 308         return NULL;
 309 }
 310
 311 static inline bool nexthop_uses_dev(const struct nexthop *nh,
 312                                     const struct net_device *dev)
 313 {
 314         struct nh_info *nhi;
 315
 316         if (nh->is_group) {
 317                 struct nh_group *nhg = rcu_dereference(nh->nh_grp);
 318                 int i;
 319
 320                 for (i = 0; i < nhg->num_nh; i++) {
 321                         struct nexthop *nhe = nhg->nh_entries[i].nh;
 322
 323                         nhi = rcu_dereference(nhe->nh_info);
 324                         if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
 325                                 return true;
 326                 }
 327         } else {
 328                 nhi = rcu_dereference(nh->nh_info);
 329                 if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
 330                         return true;
 331         }
 332
 333         return false;
 334 }
 335
 336 static inline unsigned int fib_info_num_path(const struct fib_info *fi)
 337 {
 338         if (unlikely(fi->nh))
 339                 return nexthop_num_path(fi->nh);
 340
 341         return fi->fib_nhs;
 342 }
 343
 344 int fib_check_nexthop(struct nexthop *nh, u8 scope,
 345                       struct netlink_ext_ack *extack);
 346
 347 static inline struct fib_nh_common *fib_info_nhc(struct fib_info *fi, int nhsel)
 348 {
 349         if (unlikely(fi->nh))
 350                 return nexthop_fib_nhc(fi->nh, nhsel);
 351
 352         return &fi->fib_nh[nhsel].nh_common;
 353 }
 354
 355 /* only used when fib_nh is built into fib_info */
 356 static inline struct fib_nh *fib_info_nh(struct fib_info *fi, int nhsel)
 357 {
 358         WARN_ON(fi->nh);
 359
 360         return &fi->fib_nh[nhsel];
 361 }
 362
 363 /*
 364  * IPv6 variants
 365  */
 366 int fib6_check_nexthop(struct nexthop *nh, struct fib6_config *cfg,
 367                        struct netlink_ext_ack *extack);
 368
 369 static inline struct fib6_nh *nexthop_fib6_nh(struct nexthop *nh)
 370 {
 371         struct nh_info *nhi;
 372
 373         if (nh->is_group) {
 374                 struct nh_group *nh_grp;
 375
 376                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 377                 nh = nexthop_mpath_select(nh_grp, 0);
 378                 if (!nh)
 379                         return NULL;
 380         }
 381
 382         nhi = rcu_dereference_rtnl(nh->nh_info);
 383         if (nhi->family == AF_INET6)
 384                 return &nhi->fib6_nh;
 385
 386         return NULL;
 387 }
 388
 389 static inline struct net_device *fib6_info_nh_dev(struct fib6_info *f6i)
 390 {
 391         struct fib6_nh *fib6_nh;
 392
 393         fib6_nh = f6i->nh ? nexthop_fib6_nh(f6i->nh) : f6i->fib6_nh;
 394         return fib6_nh->fib_nh_dev;
 395 }
 396
 397 static inline void nexthop_path_fib6_result(struct fib6_result *res, int hash)
 398 {
 399         struct nexthop *nh = res->f6i->nh;
 400         struct nh_info *nhi;
 401
 402         nh = nexthop_select_path(nh, hash);
 403
 404         nhi = rcu_dereference_rtnl(nh->nh_info);
 405         if (nhi->reject_nh) {
 406                 res->fib6_type = RTN_BLACKHOLE;
 407                 res->fib6_flags |= RTF_REJECT;
 408                 res->nh = nexthop_fib6_nh(nh);
 409         } else {
 410                 res->nh = &nhi->fib6_nh;
 411         }
 412 }
 413
 414 int nexthop_for_each_fib6_nh(struct nexthop *nh,
 415                              int (*cb)(struct fib6_nh *nh, void *arg),
 416                              void *arg);
 417
 418 static inline int nexthop_get_family(struct nexthop *nh)
 419 {
 420         struct nh_info *nhi = rcu_dereference_rtnl(nh->nh_info);
 421
 422         return nhi->family;
 423 }
 424
 425 static inline
 426 struct fib_nh_common *nexthop_fdb_nhc(struct nexthop *nh)
 427 {
 428         struct nh_info *nhi = rcu_dereference_rtnl(nh->nh_info);
 429
 430         return &nhi->fib_nhc;
 431 }
 432
 433 static inline struct fib_nh_common *nexthop_path_fdb_result(struct nexthop *nh,
 434                                                             int hash)
 435 {
 436         struct nh_info *nhi;
 437         struct nexthop *nhp;
 438
 439         nhp = nexthop_select_path(nh, hash);
 440         if (unlikely(!nhp))
 441                 return NULL;
 442         nhi = rcu_dereference(nhp->nh_info);
 443         return &nhi->fib_nhc;
 444 }
 445 #endif