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         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