1 /*
2  * INET		An implementation of the TCP/IP protocol suite for the LINUX
3  *		operating system.  INET  is implemented using the  BSD Socket
4  *		interface as the means of communication with the user level.
5  *
6  *		Definitions for the IP router.
7  *
8  * Version:	@(#)route.h	1.0.4	05/27/93
9  *
10  * Authors:	Ross Biro
11  *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12  * Fixes:
13  *		Alan Cox	:	Reformatted. Added ip_rt_local()
14  *		Alan Cox	:	Support for TCP parameters.
15  *		Alexey Kuznetsov:	Major changes for new routing code.
16  *		Mike McLagan    :	Routing by source
17  *		Robert Olsson   :	Added rt_cache statistics
18  *
19  *		This program is free software; you can redistribute it and/or
20  *		modify it under the terms of the GNU General Public License
21  *		as published by the Free Software Foundation; either version
22  *		2 of the License, or (at your option) any later version.
23  */
24 #ifndef _ROUTE_H
25 #define _ROUTE_H
26 
27 #include <net/dst.h>
28 #include <net/inetpeer.h>
29 #include <net/flow.h>
30 #include <net/inet_sock.h>
31 #include <net/ip_fib.h>
32 #include <linux/in_route.h>
33 #include <linux/rtnetlink.h>
34 #include <linux/rcupdate.h>
35 #include <linux/route.h>
36 #include <linux/ip.h>
37 #include <linux/cache.h>
38 #include <linux/security.h>
39 
40 /* IPv4 datagram length is stored into 16bit field (tot_len) */
41 #define IP_MAX_MTU	0xFFFFU
42 
43 #define RTO_ONLINK	0x01
44 
45 #define RT_CONN_FLAGS(sk)   (RT_TOS(inet_sk(sk)->tos) | sock_flag(sk, SOCK_LOCALROUTE))
46 #define RT_CONN_FLAGS_TOS(sk,tos)   (RT_TOS(tos) | sock_flag(sk, SOCK_LOCALROUTE))
47 
48 struct fib_nh;
49 struct fib_info;
50 struct uncached_list;
51 struct rtable {
52 	struct dst_entry	dst;
53 
54 	int			rt_genid;
55 	unsigned int		rt_flags;
56 	__u16			rt_type;
57 	__u8			rt_is_input;
58 	__u8			rt_uses_gateway;
59 
60 	int			rt_iif;
61 
62 	/* Info on neighbour */
63 	__be32			rt_gateway;
64 
65 	/* Miscellaneous cached information */
66 	u32			rt_mtu_locked:1,
67 				rt_pmtu:31;
68 
69 	struct list_head	rt_uncached;
70 	struct uncached_list	*rt_uncached_list;
71 };
72 
rt_is_input_route(const struct rtable * rt)73 static inline bool rt_is_input_route(const struct rtable *rt)
74 {
75 	return rt->rt_is_input != 0;
76 }
77 
rt_is_output_route(const struct rtable * rt)78 static inline bool rt_is_output_route(const struct rtable *rt)
79 {
80 	return rt->rt_is_input == 0;
81 }
82 
rt_nexthop(const struct rtable * rt,__be32 daddr)83 static inline __be32 rt_nexthop(const struct rtable *rt, __be32 daddr)
84 {
85 	if (rt->rt_gateway)
86 		return rt->rt_gateway;
87 	return daddr;
88 }
89 
90 struct ip_rt_acct {
91 	__u32 	o_bytes;
92 	__u32 	o_packets;
93 	__u32 	i_bytes;
94 	__u32 	i_packets;
95 };
96 
97 struct rt_cache_stat {
98         unsigned int in_slow_tot;
99         unsigned int in_slow_mc;
100         unsigned int in_no_route;
101         unsigned int in_brd;
102         unsigned int in_martian_dst;
103         unsigned int in_martian_src;
104         unsigned int out_slow_tot;
105         unsigned int out_slow_mc;
106 };
107 
108 extern struct ip_rt_acct __percpu *ip_rt_acct;
109 
110 struct in_device;
111 
112 int ip_rt_init(void);
113 void rt_cache_flush(struct net *net);
114 void rt_flush_dev(struct net_device *dev);
115 struct rtable *ip_route_output_key_hash(struct net *net, struct flowi4 *flp,
116 					const struct sk_buff *skb);
117 struct rtable *ip_route_output_key_hash_rcu(struct net *net, struct flowi4 *flp,
118 					    struct fib_result *res,
119 					    const struct sk_buff *skb);
120 
__ip_route_output_key(struct net * net,struct flowi4 * flp)121 static inline struct rtable *__ip_route_output_key(struct net *net,
122 						   struct flowi4 *flp)
123 {
124 	return ip_route_output_key_hash(net, flp, NULL);
125 }
126 
127 struct rtable *ip_route_output_flow(struct net *, struct flowi4 *flp,
128 				    const struct sock *sk);
129 struct dst_entry *ipv4_blackhole_route(struct net *net,
130 				       struct dst_entry *dst_orig);
131 
ip_route_output_key(struct net * net,struct flowi4 * flp)132 static inline struct rtable *ip_route_output_key(struct net *net, struct flowi4 *flp)
133 {
134 	return ip_route_output_flow(net, flp, NULL);
135 }
136 
ip_route_output(struct net * net,__be32 daddr,__be32 saddr,u8 tos,int oif)137 static inline struct rtable *ip_route_output(struct net *net, __be32 daddr,
138 					     __be32 saddr, u8 tos, int oif)
139 {
140 	struct flowi4 fl4 = {
141 		.flowi4_oif = oif,
142 		.flowi4_tos = tos,
143 		.daddr = daddr,
144 		.saddr = saddr,
145 	};
146 	return ip_route_output_key(net, &fl4);
147 }
148 
ip_route_output_ports(struct net * net,struct flowi4 * fl4,struct sock * sk,__be32 daddr,__be32 saddr,__be16 dport,__be16 sport,__u8 proto,__u8 tos,int oif)149 static inline struct rtable *ip_route_output_ports(struct net *net, struct flowi4 *fl4,
150 						   struct sock *sk,
151 						   __be32 daddr, __be32 saddr,
152 						   __be16 dport, __be16 sport,
153 						   __u8 proto, __u8 tos, int oif)
154 {
155 	flowi4_init_output(fl4, oif, sk ? sk->sk_mark : 0, tos,
156 			   RT_SCOPE_UNIVERSE, proto,
157 			   sk ? inet_sk_flowi_flags(sk) : 0,
158 			   daddr, saddr, dport, sport, sock_net_uid(net, sk));
159 	if (sk)
160 		security_sk_classify_flow(sk, flowi4_to_flowi(fl4));
161 	return ip_route_output_flow(net, fl4, sk);
162 }
163 
ip_route_output_gre(struct net * net,struct flowi4 * fl4,__be32 daddr,__be32 saddr,__be32 gre_key,__u8 tos,int oif)164 static inline struct rtable *ip_route_output_gre(struct net *net, struct flowi4 *fl4,
165 						 __be32 daddr, __be32 saddr,
166 						 __be32 gre_key, __u8 tos, int oif)
167 {
168 	memset(fl4, 0, sizeof(*fl4));
169 	fl4->flowi4_oif = oif;
170 	fl4->daddr = daddr;
171 	fl4->saddr = saddr;
172 	fl4->flowi4_tos = tos;
173 	fl4->flowi4_proto = IPPROTO_GRE;
174 	fl4->fl4_gre_key = gre_key;
175 	return ip_route_output_key(net, fl4);
176 }
177 int ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
178 			  u8 tos, struct net_device *dev,
179 			  struct in_device *in_dev, u32 *itag);
180 int ip_route_input_noref(struct sk_buff *skb, __be32 dst, __be32 src,
181 			 u8 tos, struct net_device *devin);
182 int ip_route_input_rcu(struct sk_buff *skb, __be32 dst, __be32 src,
183 		       u8 tos, struct net_device *devin,
184 		       struct fib_result *res);
185 
ip_route_input(struct sk_buff * skb,__be32 dst,__be32 src,u8 tos,struct net_device * devin)186 static inline int ip_route_input(struct sk_buff *skb, __be32 dst, __be32 src,
187 				 u8 tos, struct net_device *devin)
188 {
189 	int err;
190 
191 	rcu_read_lock();
192 	err = ip_route_input_noref(skb, dst, src, tos, devin);
193 	if (!err) {
194 		skb_dst_force(skb);
195 		if (!skb_dst(skb))
196 			err = -EINVAL;
197 	}
198 	rcu_read_unlock();
199 
200 	return err;
201 }
202 
203 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu, int oif,
204 		      u32 mark, u8 protocol, int flow_flags);
205 void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu);
206 void ipv4_redirect(struct sk_buff *skb, struct net *net, int oif, u32 mark,
207 		   u8 protocol, int flow_flags);
208 void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk);
209 void ip_rt_send_redirect(struct sk_buff *skb);
210 
211 unsigned int inet_addr_type(struct net *net, __be32 addr);
212 unsigned int inet_addr_type_table(struct net *net, __be32 addr, u32 tb_id);
213 unsigned int inet_dev_addr_type(struct net *net, const struct net_device *dev,
214 				__be32 addr);
215 unsigned int inet_addr_type_dev_table(struct net *net,
216 				      const struct net_device *dev,
217 				      __be32 addr);
218 void ip_rt_multicast_event(struct in_device *);
219 int ip_rt_ioctl(struct net *, unsigned int cmd, struct rtentry *rt);
220 void ip_rt_get_source(u8 *src, struct sk_buff *skb, struct rtable *rt);
221 struct rtable *rt_dst_alloc(struct net_device *dev,
222 			     unsigned int flags, u16 type,
223 			     bool nopolicy, bool noxfrm, bool will_cache);
224 
225 struct in_ifaddr;
226 void fib_add_ifaddr(struct in_ifaddr *);
227 void fib_del_ifaddr(struct in_ifaddr *, struct in_ifaddr *);
228 void fib_modify_prefix_metric(struct in_ifaddr *ifa, u32 new_metric);
229 
230 void rt_add_uncached_list(struct rtable *rt);
231 void rt_del_uncached_list(struct rtable *rt);
232 
ip_rt_put(struct rtable * rt)233 static inline void ip_rt_put(struct rtable *rt)
234 {
235 	/* dst_release() accepts a NULL parameter.
236 	 * We rely on dst being first structure in struct rtable
237 	 */
238 	BUILD_BUG_ON(offsetof(struct rtable, dst) != 0);
239 	dst_release(&rt->dst);
240 }
241 
242 #define IPTOS_RT_MASK	(IPTOS_TOS_MASK & ~3)
243 
244 extern const __u8 ip_tos2prio[16];
245 
rt_tos2priority(u8 tos)246 static inline char rt_tos2priority(u8 tos)
247 {
248 	return ip_tos2prio[IPTOS_TOS(tos)>>1];
249 }
250 
251 /* ip_route_connect() and ip_route_newports() work in tandem whilst
252  * binding a socket for a new outgoing connection.
253  *
254  * In order to use IPSEC properly, we must, in the end, have a
255  * route that was looked up using all available keys including source
256  * and destination ports.
257  *
258  * However, if a source port needs to be allocated (the user specified
259  * a wildcard source port) we need to obtain addressing information
260  * in order to perform that allocation.
261  *
262  * So ip_route_connect() looks up a route using wildcarded source and
263  * destination ports in the key, simply so that we can get a pair of
264  * addresses to use for port allocation.
265  *
266  * Later, once the ports are allocated, ip_route_newports() will make
267  * another route lookup if needed to make sure we catch any IPSEC
268  * rules keyed on the port information.
269  *
270  * The callers allocate the flow key on their stack, and must pass in
271  * the same flowi4 object to both the ip_route_connect() and the
272  * ip_route_newports() calls.
273  */
274 
ip_route_connect_init(struct flowi4 * fl4,__be32 dst,__be32 src,u32 tos,int oif,u8 protocol,__be16 sport,__be16 dport,struct sock * sk)275 static inline void ip_route_connect_init(struct flowi4 *fl4, __be32 dst, __be32 src,
276 					 u32 tos, int oif, u8 protocol,
277 					 __be16 sport, __be16 dport,
278 					 struct sock *sk)
279 {
280 	__u8 flow_flags = 0;
281 
282 	if (inet_sk(sk)->transparent)
283 		flow_flags |= FLOWI_FLAG_ANYSRC;
284 
285 	flowi4_init_output(fl4, oif, sk->sk_mark, tos, RT_SCOPE_UNIVERSE,
286 			   protocol, flow_flags, dst, src, dport, sport,
287 			   sk->sk_uid);
288 }
289 
ip_route_connect(struct flowi4 * fl4,__be32 dst,__be32 src,u32 tos,int oif,u8 protocol,__be16 sport,__be16 dport,struct sock * sk)290 static inline struct rtable *ip_route_connect(struct flowi4 *fl4,
291 					      __be32 dst, __be32 src, u32 tos,
292 					      int oif, u8 protocol,
293 					      __be16 sport, __be16 dport,
294 					      struct sock *sk)
295 {
296 	struct net *net = sock_net(sk);
297 	struct rtable *rt;
298 
299 	ip_route_connect_init(fl4, dst, src, tos, oif, protocol,
300 			      sport, dport, sk);
301 
302 	if (!dst || !src) {
303 		rt = __ip_route_output_key(net, fl4);
304 		if (IS_ERR(rt))
305 			return rt;
306 		ip_rt_put(rt);
307 		flowi4_update_output(fl4, oif, tos, fl4->daddr, fl4->saddr);
308 	}
309 	security_sk_classify_flow(sk, flowi4_to_flowi(fl4));
310 	return ip_route_output_flow(net, fl4, sk);
311 }
312 
ip_route_newports(struct flowi4 * fl4,struct rtable * rt,__be16 orig_sport,__be16 orig_dport,__be16 sport,__be16 dport,struct sock * sk)313 static inline struct rtable *ip_route_newports(struct flowi4 *fl4, struct rtable *rt,
314 					       __be16 orig_sport, __be16 orig_dport,
315 					       __be16 sport, __be16 dport,
316 					       struct sock *sk)
317 {
318 	if (sport != orig_sport || dport != orig_dport) {
319 		fl4->fl4_dport = dport;
320 		fl4->fl4_sport = sport;
321 		ip_rt_put(rt);
322 		flowi4_update_output(fl4, sk->sk_bound_dev_if,
323 				     RT_CONN_FLAGS(sk), fl4->daddr,
324 				     fl4->saddr);
325 		security_sk_classify_flow(sk, flowi4_to_flowi(fl4));
326 		return ip_route_output_flow(sock_net(sk), fl4, sk);
327 	}
328 	return rt;
329 }
330 
inet_iif(const struct sk_buff * skb)331 static inline int inet_iif(const struct sk_buff *skb)
332 {
333 	struct rtable *rt = skb_rtable(skb);
334 
335 	if (rt && rt->rt_iif)
336 		return rt->rt_iif;
337 
338 	return skb->skb_iif;
339 }
340 
ip4_dst_hoplimit(const struct dst_entry * dst)341 static inline int ip4_dst_hoplimit(const struct dst_entry *dst)
342 {
343 	int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
344 	struct net *net = dev_net(dst->dev);
345 
346 	if (hoplimit == 0)
347 		hoplimit = net->ipv4.sysctl_ip_default_ttl;
348 	return hoplimit;
349 }
350 
351 #endif	/* _ROUTE_H */
352