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
  70         union {
  71                 struct {
  72                         atomic_t        upper_bound;
  73                 } mpath;
  74         };
  75
  76         struct list_head nh_list;
  77         struct nexthop  *nh_parent;  /* nexthop of group with this entry */
  78 };
  79
  80 struct nh_group {
  81         struct nh_group         *spare; /* spare group for removals */
  82         u16                     num_nh;
  83         bool                    mpath;
  84         bool                    fdb_nh;
  85         bool                    has_v4;
  86         struct nh_grp_entry     nh_entries[];
  87 };
  88
  89 struct nexthop {
  90         struct rb_node          rb_node;    /* entry on netns rbtree */
  91         struct list_head        fi_list;    /* v4 entries using nh */
  92         struct list_head        f6i_list;   /* v6 entries using nh */
  93         struct list_head        fdb_list;   /* fdb entries using this nh */
  94         struct list_head        grp_list;   /* nh group entries using this nh */
  95         struct net              *net;
  96
  97         u32                     id;
  98
  99         u8                      protocol;   /* app managing this nh */
 100         u8                      nh_flags;
 101         bool                    is_group;
 102
 103         refcount_t              refcnt;
 104         struct rcu_head         rcu;
 105
 106         union {
 107                 struct nh_info  __rcu *nh_info;
 108                 struct nh_group __rcu *nh_grp;
 109         };
 110 };
 111
 112 enum nexthop_event_type {
 113         NEXTHOP_EVENT_DEL,
 114         NEXTHOP_EVENT_REPLACE,
 115 };
 116
 117 struct nh_notifier_single_info {
 118         struct net_device *dev;
 119         u8 gw_family;
 120         union {
 121                 __be32 ipv4;
 122                 struct in6_addr ipv6;
 123         };
 124         u8 is_reject:1,
 125            is_fdb:1,
 126            has_encap:1;
 127 };
 128
 129 struct nh_notifier_grp_entry_info {
 130         u8 weight;
 131         u32 id;
 132         struct nh_notifier_single_info nh;
 133 };
 134
 135 struct nh_notifier_grp_info {
 136         u16 num_nh;
 137         bool is_fdb;
 138         struct nh_notifier_grp_entry_info nh_entries[];
 139 };
 140
 141 struct nh_notifier_info {
 142         struct net *net;
 143         struct netlink_ext_ack *extack;
 144         u32 id;
 145         bool is_grp;
 146         union {
 147                 struct nh_notifier_single_info *nh;
 148                 struct nh_notifier_grp_info *nh_grp;
 149         };
 150 };
 151
 152 int register_nexthop_notifier(struct net *net, struct notifier_block *nb,
 153                               struct netlink_ext_ack *extack);
 154 int unregister_nexthop_notifier(struct net *net, struct notifier_block *nb);
 155 void nexthop_set_hw_flags(struct net *net, u32 id, bool offload, bool trap);
 156
 157 /* caller is holding rcu or rtnl; no reference taken to nexthop */
 158 struct nexthop *nexthop_find_by_id(struct net *net, u32 id);
 159 void nexthop_free_rcu(struct rcu_head *head);
 160
 161 static inline bool nexthop_get(struct nexthop *nh)
 162 {
 163         return refcount_inc_not_zero(&nh->refcnt);
 164 }
 165
 166 static inline void nexthop_put(struct nexthop *nh)
 167 {
 168         if (refcount_dec_and_test(&nh->refcnt))
 169                 call_rcu(&nh->rcu, nexthop_free_rcu);
 170 }
 171
 172 static inline bool nexthop_cmp(const struct nexthop *nh1,
 173                                const struct nexthop *nh2)
 174 {
 175         return nh1 == nh2;
 176 }
 177
 178 static inline bool nexthop_is_fdb(const struct nexthop *nh)
 179 {
 180         if (nh->is_group) {
 181                 const struct nh_group *nh_grp;
 182
 183                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 184                 return nh_grp->fdb_nh;
 185         } else {
 186                 const struct nh_info *nhi;
 187
 188                 nhi = rcu_dereference_rtnl(nh->nh_info);
 189                 return nhi->fdb_nh;
 190         }
 191 }
 192
 193 static inline bool nexthop_has_v4(const struct nexthop *nh)
 194 {
 195         if (nh->is_group) {
 196                 struct nh_group *nh_grp;
 197
 198                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 199                 return nh_grp->has_v4;
 200         }
 201         return false;
 202 }
 203
 204 static inline bool nexthop_is_multipath(const struct nexthop *nh)
 205 {
 206         if (nh->is_group) {
 207                 struct nh_group *nh_grp;
 208
 209                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 210                 return nh_grp->mpath;
 211         }
 212         return false;
 213 }
 214
 215 struct nexthop *nexthop_select_path(struct nexthop *nh, int hash);
 216
 217 static inline unsigned int nexthop_num_path(const struct nexthop *nh)
 218 {
 219         unsigned int rc = 1;
 220
 221         if (nh->is_group) {
 222                 struct nh_group *nh_grp;
 223
 224                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 225                 if (nh_grp->mpath)
 226                         rc = nh_grp->num_nh;
 227         }
 228
 229         return rc;
 230 }
 231
 232 static inline
 233 struct nexthop *nexthop_mpath_select(const struct nh_group *nhg, int nhsel)
 234 {
 235         /* for_nexthops macros in fib_semantics.c grabs a pointer to
 236          * the nexthop before checking nhsel
 237          */
 238         if (nhsel >= nhg->num_nh)
 239                 return NULL;
 240
 241         return nhg->nh_entries[nhsel].nh;
 242 }
 243
 244 static inline
 245 int nexthop_mpath_fill_node(struct sk_buff *skb, struct nexthop *nh,
 246                             u8 rt_family)
 247 {
 248         struct nh_group *nhg = rtnl_dereference(nh->nh_grp);
 249         int i;
 250
 251         for (i = 0; i < nhg->num_nh; i++) {
 252                 struct nexthop *nhe = nhg->nh_entries[i].nh;
 253                 struct nh_info *nhi = rcu_dereference_rtnl(nhe->nh_info);
 254                 struct fib_nh_common *nhc = &nhi->fib_nhc;
 255                 int weight = nhg->nh_entries[i].weight;
 256
 257                 if (fib_add_nexthop(skb, nhc, weight, rt_family) < 0)
 258                         return -EMSGSIZE;
 259         }
 260
 261         return 0;
 262 }
 263
 264 /* called with rcu lock */
 265 static inline bool nexthop_is_blackhole(const struct nexthop *nh)
 266 {
 267         const struct nh_info *nhi;
 268
 269         if (nh->is_group) {
 270                 struct nh_group *nh_grp;
 271
 272                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 273                 if (nh_grp->num_nh > 1)
 274                         return false;
 275
 276                 nh = nh_grp->nh_entries[0].nh;
 277         }
 278
 279         nhi = rcu_dereference_rtnl(nh->nh_info);
 280         return nhi->reject_nh;
 281 }
 282
 283 static inline void nexthop_path_fib_result(struct fib_result *res, int hash)
 284 {
 285         struct nh_info *nhi;
 286         struct nexthop *nh;
 287
 288         nh = nexthop_select_path(res->fi->nh, hash);
 289         nhi = rcu_dereference(nh->nh_info);
 290         res->nhc = &nhi->fib_nhc;
 291 }
 292
 293 /* called with rcu read lock or rtnl held */
 294 static inline
 295 struct fib_nh_common *nexthop_fib_nhc(struct nexthop *nh, int nhsel)
 296 {
 297         struct nh_info *nhi;
 298
 299         BUILD_BUG_ON(offsetof(struct fib_nh, nh_common) != 0);
 300         BUILD_BUG_ON(offsetof(struct fib6_nh, nh_common) != 0);
 301
 302         if (nh->is_group) {
 303                 struct nh_group *nh_grp;
 304
 305                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 306                 if (nh_grp->mpath) {
 307                         nh = nexthop_mpath_select(nh_grp, nhsel);
 308                         if (!nh)
 309                                 return NULL;
 310                 }
 311         }
 312
 313         nhi = rcu_dereference_rtnl(nh->nh_info);
 314         return &nhi->fib_nhc;
 315 }
 316
 317 /* called from fib_table_lookup with rcu_lock */
 318 static inline
 319 struct fib_nh_common *nexthop_get_nhc_lookup(const struct nexthop *nh,
 320                                              int fib_flags,
 321                                              const struct flowi4 *flp,
 322                                              int *nhsel)
 323 {
 324         struct nh_info *nhi;
 325
 326         if (nh->is_group) {
 327                 struct nh_group *nhg = rcu_dereference(nh->nh_grp);
 328                 int i;
 329
 330                 for (i = 0; i < nhg->num_nh; i++) {
 331                         struct nexthop *nhe = nhg->nh_entries[i].nh;
 332
 333                         nhi = rcu_dereference(nhe->nh_info);
 334                         if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
 335                                 *nhsel = i;
 336                                 return &nhi->fib_nhc;
 337                         }
 338                 }
 339         } else {
 340                 nhi = rcu_dereference(nh->nh_info);
 341                 if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
 342                         *nhsel = 0;
 343                         return &nhi->fib_nhc;
 344                 }
 345         }
 346
 347         return NULL;
 348 }
 349
 350 static inline bool nexthop_uses_dev(const struct nexthop *nh,
 351                                     const struct net_device *dev)
 352 {
 353         struct nh_info *nhi;
 354
 355         if (nh->is_group) {
 356                 struct nh_group *nhg = rcu_dereference(nh->nh_grp);
 357                 int i;
 358
 359                 for (i = 0; i < nhg->num_nh; i++) {
 360                         struct nexthop *nhe = nhg->nh_entries[i].nh;
 361
 362                         nhi = rcu_dereference(nhe->nh_info);
 363                         if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
 364                                 return true;
 365                 }
 366         } else {
 367                 nhi = rcu_dereference(nh->nh_info);
 368                 if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
 369                         return true;
 370         }
 371
 372         return false;
 373 }
 374
 375 static inline unsigned int fib_info_num_path(const struct fib_info *fi)
 376 {
 377         if (unlikely(fi->nh))
 378                 return nexthop_num_path(fi->nh);
 379
 380         return fi->fib_nhs;
 381 }
 382
 383 int fib_check_nexthop(struct nexthop *nh, u8 scope,
 384                       struct netlink_ext_ack *extack);
 385
 386 static inline struct fib_nh_common *fib_info_nhc(struct fib_info *fi, int nhsel)
 387 {
 388         if (unlikely(fi->nh))
 389                 return nexthop_fib_nhc(fi->nh, nhsel);
 390
 391         return &fi->fib_nh[nhsel].nh_common;
 392 }
 393
 394 /* only used when fib_nh is built into fib_info */
 395 static inline struct fib_nh *fib_info_nh(struct fib_info *fi, int nhsel)
 396 {
 397         WARN_ON(fi->nh);
 398
 399         return &fi->fib_nh[nhsel];
 400 }
 401
 402 /*
 403  * IPv6 variants
 404  */
 405 int fib6_check_nexthop(struct nexthop *nh, struct fib6_config *cfg,
 406                        struct netlink_ext_ack *extack);
 407
 408 static inline struct fib6_nh *nexthop_fib6_nh(struct nexthop *nh)
 409 {
 410         struct nh_info *nhi;
 411
 412         if (nh->is_group) {
 413                 struct nh_group *nh_grp;
 414
 415                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 416                 nh = nexthop_mpath_select(nh_grp, 0);
 417                 if (!nh)
 418                         return NULL;
 419         }
 420
 421         nhi = rcu_dereference_rtnl(nh->nh_info);
 422         if (nhi->family == AF_INET6)
 423                 return &nhi->fib6_nh;
 424
 425         return NULL;
 426 }
 427
 428 static inline struct net_device *fib6_info_nh_dev(struct fib6_info *f6i)
 429 {
 430         struct fib6_nh *fib6_nh;
 431
 432         fib6_nh = f6i->nh ? nexthop_fib6_nh(f6i->nh) : f6i->fib6_nh;
 433         return fib6_nh->fib_nh_dev;
 434 }
 435
 436 static inline void nexthop_path_fib6_result(struct fib6_result *res, int hash)
 437 {
 438         struct nexthop *nh = res->f6i->nh;
 439         struct nh_info *nhi;
 440
 441         nh = nexthop_select_path(nh, hash);
 442
 443         nhi = rcu_dereference_rtnl(nh->nh_info);
 444         if (nhi->reject_nh) {
 445                 res->fib6_type = RTN_BLACKHOLE;
 446                 res->fib6_flags |= RTF_REJECT;
 447                 res->nh = nexthop_fib6_nh(nh);
 448         } else {
 449                 res->nh = &nhi->fib6_nh;
 450         }
 451 }
 452
 453 int nexthop_for_each_fib6_nh(struct nexthop *nh,
 454                              int (*cb)(struct fib6_nh *nh, void *arg),
 455                              void *arg);
 456
 457 static inline int nexthop_get_family(struct nexthop *nh)
 458 {
 459         struct nh_info *nhi = rcu_dereference_rtnl(nh->nh_info);
 460
 461         return nhi->family;
 462 }
 463
 464 static inline
 465 struct fib_nh_common *nexthop_fdb_nhc(struct nexthop *nh)
 466 {
 467         struct nh_info *nhi = rcu_dereference_rtnl(nh->nh_info);
 468
 469         return &nhi->fib_nhc;
 470 }
 471
 472 static inline struct fib_nh_common *nexthop_path_fdb_result(struct nexthop *nh,
 473                                                             int hash)
 474 {
 475         struct nh_info *nhi;
 476         struct nexthop *nhp;
 477
 478         nhp = nexthop_select_path(nh, hash);
 479         if (unlikely(!nhp))
 480                 return NULL;
 481         nhi = rcu_dereference(nhp->nh_info);
 482         return &nhi->fib_nhc;
 483 }
 484 #endif