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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
21struct nexthop;
22
23struct 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
49struct 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
63struct 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
72struct nh_group {
73 u16 num_nh;
74 bool mpath;
75 bool has_v4;
76 struct nh_grp_entry nh_entries[0];
77};
78
79struct 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 */
102struct nexthop *nexthop_find_by_id(struct net *net, u32 id);
103void nexthop_free_rcu(struct rcu_head *head);
104
105static inline bool nexthop_get(struct nexthop *nh)
106{
107 return refcount_inc_not_zero(&nh->refcnt);
108}
109
110static 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
116static inline bool nexthop_cmp(const struct nexthop *nh1,
117 const struct nexthop *nh2)
118{
119 return nh1 == nh2;
120}
121
122static 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
133struct nexthop *nexthop_select_path(struct nexthop *nh, int hash);
134
135static 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
149static inline
150struct 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
163static inline
164int 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 */
184static 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
200static 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 */
211static inline
212struct 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
229static 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
237int fib_check_nexthop(struct nexthop *nh, u8 scope,
238 struct netlink_ext_ack *extack);
239
240static 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 */
249static 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 */
259int fib6_check_nexthop(struct nexthop *nh, struct fib6_config *cfg,
260 struct netlink_ext_ack *extack);
261
262static 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
279static 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
287static 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
304int nexthop_for_each_fib6_nh(struct nexthop *nh,
305 int (*cb)(struct fib6_nh *nh, void *arg),
306 void *arg);
307#endif
1#ifndef __NET_NEXTHOP_H
2#define __NET_NEXTHOP_H
3
4#include <linux/rtnetlink.h>
5#include <net/netlink.h>
6
7static inline int rtnh_ok(const struct rtnexthop *rtnh, int remaining)
8{
9 return remaining >= sizeof(*rtnh) &&
10 rtnh->rtnh_len >= sizeof(*rtnh) &&
11 rtnh->rtnh_len <= remaining;
12}
13
14static inline struct rtnexthop *rtnh_next(const struct rtnexthop *rtnh,
15 int *remaining)
16{
17 int totlen = NLA_ALIGN(rtnh->rtnh_len);
18
19 *remaining -= totlen;
20 return (struct rtnexthop *) ((char *) rtnh + totlen);
21}
22
23static inline struct nlattr *rtnh_attrs(const struct rtnexthop *rtnh)
24{
25 return (struct nlattr *) ((char *) rtnh + NLA_ALIGN(sizeof(*rtnh)));
26}
27
28static inline int rtnh_attrlen(const struct rtnexthop *rtnh)
29{
30 return rtnh->rtnh_len - NLA_ALIGN(sizeof(*rtnh));
31}
32
33#endif