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 } 145 146 return rc; 147 } 148 149 static inline 150 struct nexthop *nexthop_mpath_select(const struct nexthop *nh, int nhsel) 151 { 152 const struct nh_group *nhg = rcu_dereference_rtnl(nh->nh_grp); 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 (nexthop_is_multipath(nh)) { 189 if (nexthop_num_path(nh) > 1) 190 return false; 191 nh = nexthop_mpath_select(nh, 0); 192 if (!nh) 193 return false; 194 } 195 196 nhi = rcu_dereference_rtnl(nh->nh_info); 197 return nhi->reject_nh; 198 } 199 200 static inline void nexthop_path_fib_result(struct fib_result *res, int hash) 201 { 202 struct nh_info *nhi; 203 struct nexthop *nh; 204 205 nh = nexthop_select_path(res->fi->nh, hash); 206 nhi = rcu_dereference(nh->nh_info); 207 res->nhc = &nhi->fib_nhc; 208 } 209 210 /* called with rcu read lock or rtnl held */ 211 static inline 212 struct fib_nh_common *nexthop_fib_nhc(struct nexthop *nh, int nhsel) 213 { 214 struct nh_info *nhi; 215 216 BUILD_BUG_ON(offsetof(struct fib_nh, nh_common) != 0); 217 BUILD_BUG_ON(offsetof(struct fib6_nh, nh_common) != 0); 218 219 if (nexthop_is_multipath(nh)) { 220 nh = nexthop_mpath_select(nh, nhsel); 221 if (!nh) 222 return NULL; 223 } 224 225 nhi = rcu_dereference_rtnl(nh->nh_info); 226 return &nhi->fib_nhc; 227 } 228 229 static inline unsigned int fib_info_num_path(const struct fib_info *fi) 230 { 231 if (unlikely(fi->nh)) 232 return nexthop_num_path(fi->nh); 233 234 return fi->fib_nhs; 235 } 236 237 int fib_check_nexthop(struct nexthop *nh, u8 scope, 238 struct netlink_ext_ack *extack); 239 240 static inline struct fib_nh_common *fib_info_nhc(struct fib_info *fi, int nhsel) 241 { 242 if (unlikely(fi->nh)) 243 return nexthop_fib_nhc(fi->nh, nhsel); 244 245 return &fi->fib_nh[nhsel].nh_common; 246 } 247 248 /* only used when fib_nh is built into fib_info */ 249 static inline struct fib_nh *fib_info_nh(struct fib_info *fi, int nhsel) 250 { 251 WARN_ON(fi->nh); 252 253 return &fi->fib_nh[nhsel]; 254 } 255 256 /* 257 * IPv6 variants 258 */ 259 int fib6_check_nexthop(struct nexthop *nh, struct fib6_config *cfg, 260 struct netlink_ext_ack *extack); 261 262 static inline struct fib6_nh *nexthop_fib6_nh(struct nexthop *nh) 263 { 264 struct nh_info *nhi; 265 266 if (nexthop_is_multipath(nh)) { 267 nh = nexthop_mpath_select(nh, 0); 268 if (!nh) 269 return NULL; 270 } 271 272 nhi = rcu_dereference_rtnl(nh->nh_info); 273 if (nhi->family == AF_INET6) 274 return &nhi->fib6_nh; 275 276 return NULL; 277 } 278 279 static inline struct net_device *fib6_info_nh_dev(struct fib6_info *f6i) 280 { 281 struct fib6_nh *fib6_nh; 282 283 fib6_nh = f6i->nh ? nexthop_fib6_nh(f6i->nh) : f6i->fib6_nh; 284 return fib6_nh->fib_nh_dev; 285 } 286 287 static inline void nexthop_path_fib6_result(struct fib6_result *res, int hash) 288 { 289 struct nexthop *nh = res->f6i->nh; 290 struct nh_info *nhi; 291 292 nh = nexthop_select_path(nh, hash); 293 294 nhi = rcu_dereference_rtnl(nh->nh_info); 295 if (nhi->reject_nh) { 296 res->fib6_type = RTN_BLACKHOLE; 297 res->fib6_flags |= RTF_REJECT; 298 res->nh = nexthop_fib6_nh(nh); 299 } else { 300 res->nh = &nhi->fib6_nh; 301 } 302 } 303 304 int nexthop_for_each_fib6_nh(struct nexthop *nh, 305 int (*cb)(struct fib6_nh *nh, void *arg), 306 void *arg); 307 #endif 308