1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3  * INET		An implementation of the TCP/IP protocol suite for the LINUX
4  *		operating system.  INET  is implemented using the  BSD Socket
5  *		interface as the means of communication with the user level.
6  *
7  *		Definitions for the IP router.
8  *
9  * Version:	@(#)route.h	1.0.4	05/27/93
10  *
11  * Authors:	Ross Biro
12  *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
13  * Fixes:
14  *		Alan Cox	:	Reformatted. Added ip_rt_local()
15  *		Alan Cox	:	Support for TCP parameters.
16  *		Alexey Kuznetsov:	Major changes for new routing code.
17  *		Mike McLagan    :	Routing by source
18  *		Robert Olsson   :	Added rt_cache statistics
19  */
20 #ifndef _ROUTE_H
21 #define _ROUTE_H
22 
23 #include <net/dst.h>
24 #include <net/inetpeer.h>
25 #include <net/flow.h>
26 #include <net/inet_sock.h>
27 #include <net/ip_fib.h>
28 #include <net/arp.h>
29 #include <net/ndisc.h>
30 #include <linux/in_route.h>
31 #include <linux/rtnetlink.h>
32 #include <linux/rcupdate.h>
33 #include <linux/route.h>
34 #include <linux/ip.h>
35 #include <linux/cache.h>
36 #include <linux/security.h>
37 
38 #define RTO_ONLINK	0x01
39 
40 #define RT_CONN_FLAGS(sk)   (RT_TOS(inet_sk(sk)->tos) | sock_flag(sk, SOCK_LOCALROUTE))
41 #define RT_CONN_FLAGS_TOS(sk,tos)   (RT_TOS(tos) | sock_flag(sk, SOCK_LOCALROUTE))
42 
ip_sock_rt_scope(const struct sock * sk)43 static inline __u8 ip_sock_rt_scope(const struct sock *sk)
44 {
45 	if (sock_flag(sk, SOCK_LOCALROUTE))
46 		return RT_SCOPE_LINK;
47 
48 	return RT_SCOPE_UNIVERSE;
49 }
50 
ip_sock_rt_tos(const struct sock * sk)51 static inline __u8 ip_sock_rt_tos(const struct sock *sk)
52 {
53 	return RT_TOS(inet_sk(sk)->tos);
54 }
55 
56 struct ip_tunnel_info;
57 struct fib_nh;
58 struct fib_info;
59 struct uncached_list;
60 struct rtable {
61 	struct dst_entry	dst;
62 
63 	int			rt_genid;
64 	unsigned int		rt_flags;
65 	__u16			rt_type;
66 	__u8			rt_is_input;
67 	__u8			rt_uses_gateway;
68 
69 	int			rt_iif;
70 
71 	u8			rt_gw_family;
72 	/* Info on neighbour */
73 	union {
74 		__be32		rt_gw4;
75 		struct in6_addr	rt_gw6;
76 	};
77 
78 	/* Miscellaneous cached information */
79 	u32			rt_mtu_locked:1,
80 				rt_pmtu:31;
81 };
82 
rt_is_input_route(const struct rtable * rt)83 static inline bool rt_is_input_route(const struct rtable *rt)
84 {
85 	return rt->rt_is_input != 0;
86 }
87 
rt_is_output_route(const struct rtable * rt)88 static inline bool rt_is_output_route(const struct rtable *rt)
89 {
90 	return rt->rt_is_input == 0;
91 }
92 
rt_nexthop(const struct rtable * rt,__be32 daddr)93 static inline __be32 rt_nexthop(const struct rtable *rt, __be32 daddr)
94 {
95 	if (rt->rt_gw_family == AF_INET)
96 		return rt->rt_gw4;
97 	return daddr;
98 }
99 
100 struct ip_rt_acct {
101 	__u32 	o_bytes;
102 	__u32 	o_packets;
103 	__u32 	i_bytes;
104 	__u32 	i_packets;
105 };
106 
107 struct rt_cache_stat {
108         unsigned int in_slow_tot;
109         unsigned int in_slow_mc;
110         unsigned int in_no_route;
111         unsigned int in_brd;
112         unsigned int in_martian_dst;
113         unsigned int in_martian_src;
114         unsigned int out_slow_tot;
115         unsigned int out_slow_mc;
116 };
117 
118 extern struct ip_rt_acct __percpu *ip_rt_acct;
119 
120 struct in_device;
121 
122 int ip_rt_init(void);
123 void rt_cache_flush(struct net *net);
124 void rt_flush_dev(struct net_device *dev);
125 struct rtable *ip_route_output_key_hash(struct net *net, struct flowi4 *flp,
126 					const struct sk_buff *skb);
127 struct rtable *ip_route_output_key_hash_rcu(struct net *net, struct flowi4 *flp,
128 					    struct fib_result *res,
129 					    const struct sk_buff *skb);
130 
__ip_route_output_key(struct net * net,struct flowi4 * flp)131 static inline struct rtable *__ip_route_output_key(struct net *net,
132 						   struct flowi4 *flp)
133 {
134 	return ip_route_output_key_hash(net, flp, NULL);
135 }
136 
137 struct rtable *ip_route_output_flow(struct net *, struct flowi4 *flp,
138 				    const struct sock *sk);
139 struct rtable *ip_route_output_tunnel(struct sk_buff *skb,
140 				      struct net_device *dev,
141 				      struct net *net, __be32 *saddr,
142 				      const struct ip_tunnel_info *info,
143 				      u8 protocol, bool use_cache);
144 
145 struct dst_entry *ipv4_blackhole_route(struct net *net,
146 				       struct dst_entry *dst_orig);
147 
ip_route_output_key(struct net * net,struct flowi4 * flp)148 static inline struct rtable *ip_route_output_key(struct net *net, struct flowi4 *flp)
149 {
150 	return ip_route_output_flow(net, flp, NULL);
151 }
152 
ip_route_output(struct net * net,__be32 daddr,__be32 saddr,u8 tos,int oif)153 static inline struct rtable *ip_route_output(struct net *net, __be32 daddr,
154 					     __be32 saddr, u8 tos, int oif)
155 {
156 	struct flowi4 fl4 = {
157 		.flowi4_oif = oif,
158 		.flowi4_tos = tos,
159 		.daddr = daddr,
160 		.saddr = saddr,
161 	};
162 	return ip_route_output_key(net, &fl4);
163 }
164 
ip_route_output_ports(struct net * net,struct flowi4 * fl4,const struct sock * sk,__be32 daddr,__be32 saddr,__be16 dport,__be16 sport,__u8 proto,__u8 tos,int oif)165 static inline struct rtable *ip_route_output_ports(struct net *net, struct flowi4 *fl4,
166 						   const struct sock *sk,
167 						   __be32 daddr, __be32 saddr,
168 						   __be16 dport, __be16 sport,
169 						   __u8 proto, __u8 tos, int oif)
170 {
171 	flowi4_init_output(fl4, oif, sk ? READ_ONCE(sk->sk_mark) : 0, tos,
172 			   RT_SCOPE_UNIVERSE, proto,
173 			   sk ? inet_sk_flowi_flags(sk) : 0,
174 			   daddr, saddr, dport, sport, sock_net_uid(net, sk));
175 	if (sk)
176 		security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
177 	return ip_route_output_flow(net, fl4, sk);
178 }
179 
ip_route_output_gre(struct net * net,struct flowi4 * fl4,__be32 daddr,__be32 saddr,__be32 gre_key,__u8 tos,int oif)180 static inline struct rtable *ip_route_output_gre(struct net *net, struct flowi4 *fl4,
181 						 __be32 daddr, __be32 saddr,
182 						 __be32 gre_key, __u8 tos, int oif)
183 {
184 	memset(fl4, 0, sizeof(*fl4));
185 	fl4->flowi4_oif = oif;
186 	fl4->daddr = daddr;
187 	fl4->saddr = saddr;
188 	fl4->flowi4_tos = tos;
189 	fl4->flowi4_proto = IPPROTO_GRE;
190 	fl4->fl4_gre_key = gre_key;
191 	return ip_route_output_key(net, fl4);
192 }
193 int ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
194 			  u8 tos, struct net_device *dev,
195 			  struct in_device *in_dev, u32 *itag);
196 int ip_route_input_noref(struct sk_buff *skb, __be32 dst, __be32 src,
197 			 u8 tos, struct net_device *devin);
198 int ip_route_use_hint(struct sk_buff *skb, __be32 dst, __be32 src,
199 		      u8 tos, struct net_device *devin,
200 		      const struct sk_buff *hint);
201 
ip_route_input(struct sk_buff * skb,__be32 dst,__be32 src,u8 tos,struct net_device * devin)202 static inline int ip_route_input(struct sk_buff *skb, __be32 dst, __be32 src,
203 				 u8 tos, struct net_device *devin)
204 {
205 	int err;
206 
207 	rcu_read_lock();
208 	err = ip_route_input_noref(skb, dst, src, tos, devin);
209 	if (!err) {
210 		skb_dst_force(skb);
211 		if (!skb_dst(skb))
212 			err = -EINVAL;
213 	}
214 	rcu_read_unlock();
215 
216 	return err;
217 }
218 
219 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu, int oif,
220 		      u8 protocol);
221 void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu);
222 void ipv4_redirect(struct sk_buff *skb, struct net *net, int oif, u8 protocol);
223 void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk);
224 void ip_rt_send_redirect(struct sk_buff *skb);
225 
226 unsigned int inet_addr_type(struct net *net, __be32 addr);
227 unsigned int inet_addr_type_table(struct net *net, __be32 addr, u32 tb_id);
228 unsigned int inet_dev_addr_type(struct net *net, const struct net_device *dev,
229 				__be32 addr);
230 unsigned int inet_addr_type_dev_table(struct net *net,
231 				      const struct net_device *dev,
232 				      __be32 addr);
233 void ip_rt_multicast_event(struct in_device *);
234 int ip_rt_ioctl(struct net *, unsigned int cmd, struct rtentry *rt);
235 void ip_rt_get_source(u8 *src, struct sk_buff *skb, struct rtable *rt);
236 struct rtable *rt_dst_alloc(struct net_device *dev,
237 			    unsigned int flags, u16 type, bool noxfrm);
238 struct rtable *rt_dst_clone(struct net_device *dev, struct rtable *rt);
239 
240 struct in_ifaddr;
241 void fib_add_ifaddr(struct in_ifaddr *);
242 void fib_del_ifaddr(struct in_ifaddr *, struct in_ifaddr *);
243 void fib_modify_prefix_metric(struct in_ifaddr *ifa, u32 new_metric);
244 
245 void rt_add_uncached_list(struct rtable *rt);
246 void rt_del_uncached_list(struct rtable *rt);
247 
248 int fib_dump_info_fnhe(struct sk_buff *skb, struct netlink_callback *cb,
249 		       u32 table_id, struct fib_info *fi,
250 		       int *fa_index, int fa_start, unsigned int flags);
251 
ip_rt_put(struct rtable * rt)252 static inline void ip_rt_put(struct rtable *rt)
253 {
254 	/* dst_release() accepts a NULL parameter.
255 	 * We rely on dst being first structure in struct rtable
256 	 */
257 	BUILD_BUG_ON(offsetof(struct rtable, dst) != 0);
258 	dst_release(&rt->dst);
259 }
260 
261 #define IPTOS_RT_MASK	(IPTOS_TOS_MASK & ~3)
262 
263 extern const __u8 ip_tos2prio[16];
264 
rt_tos2priority(u8 tos)265 static inline char rt_tos2priority(u8 tos)
266 {
267 	return ip_tos2prio[IPTOS_TOS(tos)>>1];
268 }
269 
270 /* ip_route_connect() and ip_route_newports() work in tandem whilst
271  * binding a socket for a new outgoing connection.
272  *
273  * In order to use IPSEC properly, we must, in the end, have a
274  * route that was looked up using all available keys including source
275  * and destination ports.
276  *
277  * However, if a source port needs to be allocated (the user specified
278  * a wildcard source port) we need to obtain addressing information
279  * in order to perform that allocation.
280  *
281  * So ip_route_connect() looks up a route using wildcarded source and
282  * destination ports in the key, simply so that we can get a pair of
283  * addresses to use for port allocation.
284  *
285  * Later, once the ports are allocated, ip_route_newports() will make
286  * another route lookup if needed to make sure we catch any IPSEC
287  * rules keyed on the port information.
288  *
289  * The callers allocate the flow key on their stack, and must pass in
290  * the same flowi4 object to both the ip_route_connect() and the
291  * ip_route_newports() calls.
292  */
293 
ip_route_connect_init(struct flowi4 * fl4,__be32 dst,__be32 src,int oif,u8 protocol,__be16 sport,__be16 dport,const struct sock * sk)294 static inline void ip_route_connect_init(struct flowi4 *fl4, __be32 dst,
295 					 __be32 src, int oif, u8 protocol,
296 					 __be16 sport, __be16 dport,
297 					 const struct sock *sk)
298 {
299 	__u8 flow_flags = 0;
300 
301 	if (inet_test_bit(TRANSPARENT, sk))
302 		flow_flags |= FLOWI_FLAG_ANYSRC;
303 
304 	flowi4_init_output(fl4, oif, READ_ONCE(sk->sk_mark), ip_sock_rt_tos(sk),
305 			   ip_sock_rt_scope(sk), protocol, flow_flags, dst,
306 			   src, dport, sport, sk->sk_uid);
307 }
308 
ip_route_connect(struct flowi4 * fl4,__be32 dst,__be32 src,int oif,u8 protocol,__be16 sport,__be16 dport,const struct sock * sk)309 static inline struct rtable *ip_route_connect(struct flowi4 *fl4, __be32 dst,
310 					      __be32 src, int oif, u8 protocol,
311 					      __be16 sport, __be16 dport,
312 					      const struct sock *sk)
313 {
314 	struct net *net = sock_net(sk);
315 	struct rtable *rt;
316 
317 	ip_route_connect_init(fl4, dst, src, oif, protocol, sport, dport, sk);
318 
319 	if (!dst || !src) {
320 		rt = __ip_route_output_key(net, fl4);
321 		if (IS_ERR(rt))
322 			return rt;
323 		ip_rt_put(rt);
324 		flowi4_update_output(fl4, oif, fl4->daddr, fl4->saddr);
325 	}
326 	security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
327 	return ip_route_output_flow(net, fl4, sk);
328 }
329 
ip_route_newports(struct flowi4 * fl4,struct rtable * rt,__be16 orig_sport,__be16 orig_dport,__be16 sport,__be16 dport,const struct sock * sk)330 static inline struct rtable *ip_route_newports(struct flowi4 *fl4, struct rtable *rt,
331 					       __be16 orig_sport, __be16 orig_dport,
332 					       __be16 sport, __be16 dport,
333 					       const struct sock *sk)
334 {
335 	if (sport != orig_sport || dport != orig_dport) {
336 		fl4->fl4_dport = dport;
337 		fl4->fl4_sport = sport;
338 		ip_rt_put(rt);
339 		flowi4_update_output(fl4, sk->sk_bound_dev_if, fl4->daddr,
340 				     fl4->saddr);
341 		security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
342 		return ip_route_output_flow(sock_net(sk), fl4, sk);
343 	}
344 	return rt;
345 }
346 
inet_iif(const struct sk_buff * skb)347 static inline int inet_iif(const struct sk_buff *skb)
348 {
349 	struct rtable *rt = skb_rtable(skb);
350 
351 	if (rt && rt->rt_iif)
352 		return rt->rt_iif;
353 
354 	return skb->skb_iif;
355 }
356 
ip4_dst_hoplimit(const struct dst_entry * dst)357 static inline int ip4_dst_hoplimit(const struct dst_entry *dst)
358 {
359 	int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
360 	struct net *net = dev_net(dst->dev);
361 
362 	if (hoplimit == 0)
363 		hoplimit = READ_ONCE(net->ipv4.sysctl_ip_default_ttl);
364 	return hoplimit;
365 }
366 
ip_neigh_gw4(struct net_device * dev,__be32 daddr)367 static inline struct neighbour *ip_neigh_gw4(struct net_device *dev,
368 					     __be32 daddr)
369 {
370 	struct neighbour *neigh;
371 
372 	neigh = __ipv4_neigh_lookup_noref(dev, (__force u32)daddr);
373 	if (unlikely(!neigh))
374 		neigh = __neigh_create(&arp_tbl, &daddr, dev, false);
375 
376 	return neigh;
377 }
378 
ip_neigh_for_gw(struct rtable * rt,struct sk_buff * skb,bool * is_v6gw)379 static inline struct neighbour *ip_neigh_for_gw(struct rtable *rt,
380 						struct sk_buff *skb,
381 						bool *is_v6gw)
382 {
383 	struct net_device *dev = rt->dst.dev;
384 	struct neighbour *neigh;
385 
386 	if (likely(rt->rt_gw_family == AF_INET)) {
387 		neigh = ip_neigh_gw4(dev, rt->rt_gw4);
388 	} else if (rt->rt_gw_family == AF_INET6) {
389 		neigh = ip_neigh_gw6(dev, &rt->rt_gw6);
390 		*is_v6gw = true;
391 	} else {
392 		neigh = ip_neigh_gw4(dev, ip_hdr(skb)->daddr);
393 	}
394 	return neigh;
395 }
396 
397 #endif	/* _ROUTE_H */
398