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 376