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/route.h>
  14 #include <linux/types.h>
  15 #include <net/ip_fib.h>
  16 #include <net/ip6_fib.h>
  17 #include <net/netlink.h>
  18
  19 #define NEXTHOP_VALID_USER_FLAGS RTNH_F_ONLINK
  20
  21 struct nexthop;
  22
  23 struct nh_config {
  24         u32             nh_id;
  25
  26         u8              nh_family;
  27         u8              nh_protocol;
  28         u8              nh_blackhole;
  29         u32             nh_flags;
  30
  31         int             nh_ifindex;
  32         struct net_device *dev;
  33
  34         union {
  35                 __be32          ipv4;
  36                 struct in6_addr ipv6;
  37         } gw;
  38
  39         struct nlattr   *nh_grp;
  40         u16             nh_grp_type;
  41
  42         struct nlattr   *nh_encap;
  43         u16             nh_encap_type;
  44
  45         u32             nlflags;
  46         struct nl_info  nlinfo;
  47 };
  48
  49 struct nh_info {
  50         struct hlist_node       dev_hash;    /* entry on netns devhash */
  51         struct nexthop          *nh_parent;
  52
  53         u8                      family;
  54         bool                    reject_nh;
  55
  56         union {
  57                 struct fib_nh_common    fib_nhc;
  58                 struct fib_nh           fib_nh;
  59                 struct fib6_nh          fib6_nh;
  60         };
  61 };
  62
  63 struct nh_grp_entry {
  64         struct nexthop  *nh;
  65         u8              weight;
  66         atomic_t        upper_bound;
  67
  68         struct list_head nh_list;
  69         struct nexthop  *nh_parent;  /* nexthop of group with this entry */
  70 };
  71
  72 struct nh_group {
  73         struct nh_group         *spare; /* spare group for removals */
  74         u16                     num_nh;
  75         bool                    mpath;
  76         bool                    has_v4;
  77         struct nh_grp_entry     nh_entries[];
  78 };
  79
  80 struct nexthop {
  81         struct rb_node          rb_node;    /* entry on netns rbtree */
  82         struct list_head        fi_list;    /* v4 entries using nh */
  83         struct list_head        f6i_list;   /* v6 entries using nh */
  84         struct list_head        grp_list;   /* nh group entries using this nh */
  85         struct net              *net;
  86
  87         u32                     id;
  88
  89         u8                      protocol;   /* app managing this nh */
  90         u8                      nh_flags;
  91         bool                    is_group;
  92
  93         refcount_t              refcnt;
  94         struct rcu_head         rcu;
  95
  96         union {
  97                 struct nh_info  __rcu *nh_info;
  98                 struct nh_group __rcu *nh_grp;
  99         };
 100 };
 101
 102 /* caller is holding rcu or rtnl; no reference taken to nexthop */
 103 struct nexthop *nexthop_find_by_id(struct net *net, u32 id);
 104 void nexthop_free_rcu(struct rcu_head *head);
 105
 106 static inline bool nexthop_get(struct nexthop *nh)
 107 {
 108         return refcount_inc_not_zero(&nh->refcnt);
 109 }
 110
 111 static inline void nexthop_put(struct nexthop *nh)
 112 {
 113         if (refcount_dec_and_test(&nh->refcnt))
 114                 call_rcu(&nh->rcu, nexthop_free_rcu);
 115 }
 116
 117 static inline bool nexthop_cmp(const struct nexthop *nh1,
 118                                const struct nexthop *nh2)
 119 {
 120         return nh1 == nh2;
 121 }
 122
 123 static inline bool nexthop_is_multipath(const struct nexthop *nh)
 124 {
 125         if (nh->is_group) {
 126                 struct nh_group *nh_grp;
 127
 128                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 129                 return nh_grp->mpath;
 130         }
 131         return false;
 132 }
 133
 134 struct nexthop *nexthop_select_path(struct nexthop *nh, int hash);
 135
 136 static inline unsigned int nexthop_num_path(const struct nexthop *nh)
 137 {
 138         unsigned int rc = 1;
 139
 140         if (nh->is_group) {
 141                 struct nh_group *nh_grp;
 142
 143                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 144                 if (nh_grp->mpath)
 145                         rc = nh_grp->num_nh;
 146         }
 147
 148         return rc;
 149 }
 150
 151 static inline
 152 struct nexthop *nexthop_mpath_select(const struct nh_group *nhg, int nhsel)
 153 {
 154         /* for_nexthops macros in fib_semantics.c grabs a pointer to
 155          * the nexthop before checking nhsel
 156          */
 157         if (nhsel >= nhg->num_nh)
 158                 return NULL;
 159
 160         return nhg->nh_entries[nhsel].nh;
 161 }
 162
 163 static inline
 164 int nexthop_mpath_fill_node(struct sk_buff *skb, struct nexthop *nh,
 165                             u8 rt_family)
 166 {
 167         struct nh_group *nhg = rtnl_dereference(nh->nh_grp);
 168         int i;
 169
 170         for (i = 0; i < nhg->num_nh; i++) {
 171                 struct nexthop *nhe = nhg->nh_entries[i].nh;
 172                 struct nh_info *nhi = rcu_dereference_rtnl(nhe->nh_info);
 173                 struct fib_nh_common *nhc = &nhi->fib_nhc;
 174                 int weight = nhg->nh_entries[i].weight;
 175
 176                 if (fib_add_nexthop(skb, nhc, weight, rt_family) < 0)
 177                         return -EMSGSIZE;
 178         }
 179
 180         return 0;
 181 }
 182
 183 /* called with rcu lock */
 184 static inline bool nexthop_is_blackhole(const struct nexthop *nh)
 185 {
 186         const struct nh_info *nhi;
 187
 188         if (nh->is_group) {
 189                 struct nh_group *nh_grp;
 190
 191                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 192                 if (nh_grp->num_nh > 1)
 193                         return false;
 194
 195                 nh = nh_grp->nh_entries[0].nh;
 196         }
 197
 198         nhi = rcu_dereference_rtnl(nh->nh_info);
 199         return nhi->reject_nh;
 200 }
 201
 202 static inline void nexthop_path_fib_result(struct fib_result *res, int hash)
 203 {
 204         struct nh_info *nhi;
 205         struct nexthop *nh;
 206
 207         nh = nexthop_select_path(res->fi->nh, hash);
 208         nhi = rcu_dereference(nh->nh_info);
 209         res->nhc = &nhi->fib_nhc;
 210 }
 211
 212 /* called with rcu read lock or rtnl held */
 213 static inline
 214 struct fib_nh_common *nexthop_fib_nhc(struct nexthop *nh, int nhsel)
 215 {
 216         struct nh_info *nhi;
 217
 218         BUILD_BUG_ON(offsetof(struct fib_nh, nh_common) != 0);
 219         BUILD_BUG_ON(offsetof(struct fib6_nh, nh_common) != 0);
 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                         nh = nexthop_mpath_select(nh_grp, nhsel);
 227                         if (!nh)
 228                                 return NULL;
 229                 }
 230         }
 231
 232         nhi = rcu_dereference_rtnl(nh->nh_info);
 233         return &nhi->fib_nhc;
 234 }
 235
 236 /* called from fib_table_lookup with rcu_lock */
 237 static inline
 238 struct fib_nh_common *nexthop_get_nhc_lookup(const struct nexthop *nh,
 239                                              int fib_flags,
 240                                              const struct flowi4 *flp,
 241                                              int *nhsel)
 242 {
 243         struct nh_info *nhi;
 244
 245         if (nh->is_group) {
 246                 struct nh_group *nhg = rcu_dereference(nh->nh_grp);
 247                 int i;
 248
 249                 for (i = 0; i < nhg->num_nh; i++) {
 250                         struct nexthop *nhe = nhg->nh_entries[i].nh;
 251
 252                         nhi = rcu_dereference(nhe->nh_info);
 253                         if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
 254                                 *nhsel = i;
 255                                 return &nhi->fib_nhc;
 256                         }
 257                 }
 258         } else {
 259                 nhi = rcu_dereference(nh->nh_info);
 260                 if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
 261                         *nhsel = 0;
 262                         return &nhi->fib_nhc;
 263                 }
 264         }
 265
 266         return NULL;
 267 }
 268
 269 static inline bool nexthop_uses_dev(const struct nexthop *nh,
 270                                     const struct net_device *dev)
 271 {
 272         struct nh_info *nhi;
 273
 274         if (nh->is_group) {
 275                 struct nh_group *nhg = rcu_dereference(nh->nh_grp);
 276                 int i;
 277
 278                 for (i = 0; i < nhg->num_nh; i++) {
 279                         struct nexthop *nhe = nhg->nh_entries[i].nh;
 280
 281                         nhi = rcu_dereference(nhe->nh_info);
 282                         if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
 283                                 return true;
 284                 }
 285         } else {
 286                 nhi = rcu_dereference(nh->nh_info);
 287                 if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
 288                         return true;
 289         }
 290
 291         return false;
 292 }
 293
 294 static inline unsigned int fib_info_num_path(const struct fib_info *fi)
 295 {
 296         if (unlikely(fi->nh))
 297                 return nexthop_num_path(fi->nh);
 298
 299         return fi->fib_nhs;
 300 }
 301
 302 int fib_check_nexthop(struct nexthop *nh, u8 scope,
 303                       struct netlink_ext_ack *extack);
 304
 305 static inline struct fib_nh_common *fib_info_nhc(struct fib_info *fi, int nhsel)
 306 {
 307         if (unlikely(fi->nh))
 308                 return nexthop_fib_nhc(fi->nh, nhsel);
 309
 310         return &fi->fib_nh[nhsel].nh_common;
 311 }
 312
 313 /* only used when fib_nh is built into fib_info */
 314 static inline struct fib_nh *fib_info_nh(struct fib_info *fi, int nhsel)
 315 {
 316         WARN_ON(fi->nh);
 317
 318         return &fi->fib_nh[nhsel];
 319 }
 320
 321 /*
 322  * IPv6 variants
 323  */
 324 int fib6_check_nexthop(struct nexthop *nh, struct fib6_config *cfg,
 325                        struct netlink_ext_ack *extack);
 326
 327 static inline struct fib6_nh *nexthop_fib6_nh(struct nexthop *nh)
 328 {
 329         struct nh_info *nhi;
 330
 331         if (nh->is_group) {
 332                 struct nh_group *nh_grp;
 333
 334                 nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 335                 nh = nexthop_mpath_select(nh_grp, 0);
 336                 if (!nh)
 337                         return NULL;
 338         }
 339
 340         nhi = rcu_dereference_rtnl(nh->nh_info);
 341         if (nhi->family == AF_INET6)
 342                 return &nhi->fib6_nh;
 343
 344         return NULL;
 345 }
 346
 347 static inline struct net_device *fib6_info_nh_dev(struct fib6_info *f6i)
 348 {
 349         struct fib6_nh *fib6_nh;
 350
 351         fib6_nh = f6i->nh ? nexthop_fib6_nh(f6i->nh) : f6i->fib6_nh;
 352         return fib6_nh->fib_nh_dev;
 353 }
 354
 355 static inline void nexthop_path_fib6_result(struct fib6_result *res, int hash)
 356 {
 357         struct nexthop *nh = res->f6i->nh;
 358         struct nh_info *nhi;
 359
 360         nh = nexthop_select_path(nh, hash);
 361
 362         nhi = rcu_dereference_rtnl(nh->nh_info);
 363         if (nhi->reject_nh) {
 364                 res->fib6_type = RTN_BLACKHOLE;
 365                 res->fib6_flags |= RTF_REJECT;
 366                 res->nh = nexthop_fib6_nh(nh);
 367         } else {
 368                 res->nh = &nhi->fib6_nh;
 369         }
 370 }
 371
 372 int nexthop_for_each_fib6_nh(struct nexthop *nh,
 373                              int (*cb)(struct fib6_nh *nh, void *arg),
 374                              void *arg);
 375 #endif