xref: /openbmc/linux/include/net/nexthop.h (revision f8e17c17)
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