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 u16 num_nh; 74 bool mpath; 75 bool has_v4; 76 struct nh_grp_entry nh_entries[0]; 77 }; 78 79 struct nexthop { 80 struct rb_node rb_node; /* entry on netns rbtree */ 81 struct list_head fi_list; /* v4 entries using nh */ 82 struct list_head f6i_list; /* v6 entries using nh */ 83 struct list_head grp_list; /* nh group entries using this nh */ 84 struct net *net; 85 86 u32 id; 87 88 u8 protocol; /* app managing this nh */ 89 u8 nh_flags; 90 bool is_group; 91 92 refcount_t refcnt; 93 struct rcu_head rcu; 94 95 union { 96 struct nh_info __rcu *nh_info; 97 struct nh_group __rcu *nh_grp; 98 }; 99 }; 100 101 /* caller is holding rcu or rtnl; no reference taken to nexthop */ 102 struct nexthop *nexthop_find_by_id(struct net *net, u32 id); 103 void nexthop_free_rcu(struct rcu_head *head); 104 105 static inline bool nexthop_get(struct nexthop *nh) 106 { 107 return refcount_inc_not_zero(&nh->refcnt); 108 } 109 110 static inline void nexthop_put(struct nexthop *nh) 111 { 112 if (refcount_dec_and_test(&nh->refcnt)) 113 call_rcu(&nh->rcu, nexthop_free_rcu); 114 } 115 116 static inline bool nexthop_cmp(const struct nexthop *nh1, 117 const struct nexthop *nh2) 118 { 119 return nh1 == nh2; 120 } 121 122 static inline bool nexthop_is_multipath(const struct nexthop *nh) 123 { 124 if (nh->is_group) { 125 struct nh_group *nh_grp; 126 127 nh_grp = rcu_dereference_rtnl(nh->nh_grp); 128 return nh_grp->mpath; 129 } 130 return false; 131 } 132 133 struct nexthop *nexthop_select_path(struct nexthop *nh, int hash); 134 135 static inline unsigned int nexthop_num_path(const struct nexthop *nh) 136 { 137 unsigned int rc = 1; 138 139 if (nexthop_is_multipath(nh)) { 140 struct nh_group *nh_grp; 141 142 nh_grp = rcu_dereference_rtnl(nh->nh_grp); 143 rc = nh_grp->num_nh; 144 } else { 145 const struct nh_info *nhi; 146 147 nhi = rcu_dereference_rtnl(nh->nh_info); 148 if (nhi->reject_nh) 149 rc = 0; 150 } 151 152 return rc; 153 } 154 155 static inline 156 struct nexthop *nexthop_mpath_select(const struct nexthop *nh, int nhsel) 157 { 158 const struct nh_group *nhg = rcu_dereference_rtnl(nh->nh_grp); 159 160 /* for_nexthops macros in fib_semantics.c grabs a pointer to 161 * the nexthop before checking nhsel 162 */ 163 if (nhsel >= nhg->num_nh) 164 return NULL; 165 166 return nhg->nh_entries[nhsel].nh; 167 } 168 169 static inline 170 int nexthop_mpath_fill_node(struct sk_buff *skb, struct nexthop *nh) 171 { 172 struct nh_group *nhg = rtnl_dereference(nh->nh_grp); 173 int i; 174 175 for (i = 0; i < nhg->num_nh; i++) { 176 struct nexthop *nhe = nhg->nh_entries[i].nh; 177 struct nh_info *nhi = rcu_dereference_rtnl(nhe->nh_info); 178 struct fib_nh_common *nhc = &nhi->fib_nhc; 179 int weight = nhg->nh_entries[i].weight; 180 181 if (fib_add_nexthop(skb, nhc, weight) < 0) 182 return -EMSGSIZE; 183 } 184 185 return 0; 186 } 187 188 /* called with rcu lock */ 189 static inline bool nexthop_is_blackhole(const struct nexthop *nh) 190 { 191 const struct nh_info *nhi; 192 193 if (nexthop_is_multipath(nh)) { 194 if (nexthop_num_path(nh) > 1) 195 return false; 196 nh = nexthop_mpath_select(nh, 0); 197 if (!nh) 198 return false; 199 } 200 201 nhi = rcu_dereference_rtnl(nh->nh_info); 202 return nhi->reject_nh; 203 } 204 205 static inline void nexthop_path_fib_result(struct fib_result *res, int hash) 206 { 207 struct nh_info *nhi; 208 struct nexthop *nh; 209 210 nh = nexthop_select_path(res->fi->nh, hash); 211 nhi = rcu_dereference(nh->nh_info); 212 res->nhc = &nhi->fib_nhc; 213 } 214 215 /* called with rcu read lock or rtnl held */ 216 static inline 217 struct fib_nh_common *nexthop_fib_nhc(struct nexthop *nh, int nhsel) 218 { 219 struct nh_info *nhi; 220 221 BUILD_BUG_ON(offsetof(struct fib_nh, nh_common) != 0); 222 BUILD_BUG_ON(offsetof(struct fib6_nh, nh_common) != 0); 223 224 if (nexthop_is_multipath(nh)) { 225 nh = nexthop_mpath_select(nh, nhsel); 226 if (!nh) 227 return NULL; 228 } 229 230 nhi = rcu_dereference_rtnl(nh->nh_info); 231 return &nhi->fib_nhc; 232 } 233 234 static inline unsigned int fib_info_num_path(const struct fib_info *fi) 235 { 236 if (unlikely(fi->nh)) 237 return nexthop_num_path(fi->nh); 238 239 return fi->fib_nhs; 240 } 241 242 int fib_check_nexthop(struct nexthop *nh, u8 scope, 243 struct netlink_ext_ack *extack); 244 245 static inline struct fib_nh_common *fib_info_nhc(struct fib_info *fi, int nhsel) 246 { 247 if (unlikely(fi->nh)) 248 return nexthop_fib_nhc(fi->nh, nhsel); 249 250 return &fi->fib_nh[nhsel].nh_common; 251 } 252 253 /* only used when fib_nh is built into fib_info */ 254 static inline struct fib_nh *fib_info_nh(struct fib_info *fi, int nhsel) 255 { 256 WARN_ON(fi->nh); 257 258 return &fi->fib_nh[nhsel]; 259 } 260 261 /* 262 * IPv6 variants 263 */ 264 int fib6_check_nexthop(struct nexthop *nh, struct fib6_config *cfg, 265 struct netlink_ext_ack *extack); 266 267 static inline struct fib6_nh *nexthop_fib6_nh(struct nexthop *nh) 268 { 269 struct nh_info *nhi; 270 271 if (nexthop_is_multipath(nh)) { 272 nh = nexthop_mpath_select(nh, 0); 273 if (!nh) 274 return NULL; 275 } 276 277 nhi = rcu_dereference_rtnl(nh->nh_info); 278 if (nhi->family == AF_INET6) 279 return &nhi->fib6_nh; 280 281 return NULL; 282 } 283 284 static inline struct net_device *fib6_info_nh_dev(struct fib6_info *f6i) 285 { 286 struct fib6_nh *fib6_nh; 287 288 fib6_nh = f6i->nh ? nexthop_fib6_nh(f6i->nh) : f6i->fib6_nh; 289 return fib6_nh->fib_nh_dev; 290 } 291 292 static inline void nexthop_path_fib6_result(struct fib6_result *res, int hash) 293 { 294 struct nexthop *nh = res->f6i->nh; 295 struct nh_info *nhi; 296 297 nh = nexthop_select_path(nh, hash); 298 299 nhi = rcu_dereference_rtnl(nh->nh_info); 300 if (nhi->reject_nh) { 301 res->fib6_type = RTN_BLACKHOLE; 302 res->fib6_flags |= RTF_REJECT; 303 res->nh = nexthop_fib6_nh(nh); 304 } else { 305 res->nh = &nhi->fib6_nh; 306 } 307 } 308 309 int nexthop_for_each_fib6_nh(struct nexthop *nh, 310 int (*cb)(struct fib6_nh *nh, void *arg), 311 void *arg); 312 #endif 313