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Linux/include/net/route.h

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  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 /* IPv4 datagram length is stored into 16bit field (tot_len) */
 39 #define IP_MAX_MTU      0xFFFFU
 40 
 41 #define RTO_ONLINK      0x01
 42 
 43 #define RT_CONN_FLAGS(sk)   (RT_TOS(inet_sk(sk)->tos) | sock_flag(sk, SOCK_LOCALROUTE))
 44 #define RT_CONN_FLAGS_TOS(sk,tos)   (RT_TOS(tos) | sock_flag(sk, SOCK_LOCALROUTE))
 45 
 46 struct fib_nh;
 47 struct fib_info;
 48 struct uncached_list;
 49 struct rtable {
 50         struct dst_entry        dst;
 51 
 52         int                     rt_genid;
 53         unsigned int            rt_flags;
 54         __u16                   rt_type;
 55         __u8                    rt_is_input;
 56         __u8                    rt_uses_gateway;
 57 
 58         int                     rt_iif;
 59 
 60         u8                      rt_gw_family;
 61         /* Info on neighbour */
 62         union {
 63                 __be32          rt_gw4;
 64                 struct in6_addr rt_gw6;
 65         };
 66 
 67         /* Miscellaneous cached information */
 68         u32                     rt_mtu_locked:1,
 69                                 rt_pmtu:31;
 70 
 71         struct list_head        rt_uncached;
 72         struct uncached_list    *rt_uncached_list;
 73 };
 74 
 75 static inline bool rt_is_input_route(const struct rtable *rt)
 76 {
 77         return rt->rt_is_input != 0;
 78 }
 79 
 80 static inline bool rt_is_output_route(const struct rtable *rt)
 81 {
 82         return rt->rt_is_input == 0;
 83 }
 84 
 85 static inline __be32 rt_nexthop(const struct rtable *rt, __be32 daddr)
 86 {
 87         if (rt->rt_gw_family == AF_INET)
 88                 return rt->rt_gw4;
 89         return daddr;
 90 }
 91 
 92 struct ip_rt_acct {
 93         __u32   o_bytes;
 94         __u32   o_packets;
 95         __u32   i_bytes;
 96         __u32   i_packets;
 97 };
 98 
 99 struct rt_cache_stat {
100         unsigned int in_slow_tot;
101         unsigned int in_slow_mc;
102         unsigned int in_no_route;
103         unsigned int in_brd;
104         unsigned int in_martian_dst;
105         unsigned int in_martian_src;
106         unsigned int out_slow_tot;
107         unsigned int out_slow_mc;
108 };
109 
110 extern struct ip_rt_acct __percpu *ip_rt_acct;
111 
112 struct in_device;
113 
114 int ip_rt_init(void);
115 void rt_cache_flush(struct net *net);
116 void rt_flush_dev(struct net_device *dev);
117 struct rtable *ip_route_output_key_hash(struct net *net, struct flowi4 *flp,
118                                         const struct sk_buff *skb);
119 struct rtable *ip_route_output_key_hash_rcu(struct net *net, struct flowi4 *flp,
120                                             struct fib_result *res,
121                                             const struct sk_buff *skb);
122 
123 static inline struct rtable *__ip_route_output_key(struct net *net,
124                                                    struct flowi4 *flp)
125 {
126         return ip_route_output_key_hash(net, flp, NULL);
127 }
128 
129 struct rtable *ip_route_output_flow(struct net *, struct flowi4 *flp,
130                                     const struct sock *sk);
131 struct rtable *ip_route_output_tunnel(struct sk_buff *skb,
132                                       struct net_device *dev,
133                                       struct net *net, __be32 *saddr,
134                                       const struct ip_tunnel_info *info,
135                                       u8 protocol, bool use_cache);
136 
137 struct dst_entry *ipv4_blackhole_route(struct net *net,
138                                        struct dst_entry *dst_orig);
139 
140 static inline struct rtable *ip_route_output_key(struct net *net, struct flowi4 *flp)
141 {
142         return ip_route_output_flow(net, flp, NULL);
143 }
144 
145 static inline struct rtable *ip_route_output(struct net *net, __be32 daddr,
146                                              __be32 saddr, u8 tos, int oif)
147 {
148         struct flowi4 fl4 = {
149                 .flowi4_oif = oif,
150                 .flowi4_tos = tos,
151                 .daddr = daddr,
152                 .saddr = saddr,
153         };
154         return ip_route_output_key(net, &fl4);
155 }
156 
157 static inline struct rtable *ip_route_output_ports(struct net *net, struct flowi4 *fl4,
158                                                    struct sock *sk,
159                                                    __be32 daddr, __be32 saddr,
160                                                    __be16 dport, __be16 sport,
161                                                    __u8 proto, __u8 tos, int oif)
162 {
163         flowi4_init_output(fl4, oif, sk ? sk->sk_mark : 0, tos,
164                            RT_SCOPE_UNIVERSE, proto,
165                            sk ? inet_sk_flowi_flags(sk) : 0,
166                            daddr, saddr, dport, sport, sock_net_uid(net, sk));
167         if (sk)
168                 security_sk_classify_flow(sk, flowi4_to_flowi(fl4));
169         return ip_route_output_flow(net, fl4, sk);
170 }
171 
172 static inline struct rtable *ip_route_output_gre(struct net *net, struct flowi4 *fl4,
173                                                  __be32 daddr, __be32 saddr,
174                                                  __be32 gre_key, __u8 tos, int oif)
175 {
176         memset(fl4, 0, sizeof(*fl4));
177         fl4->flowi4_oif = oif;
178         fl4->daddr = daddr;
179         fl4->saddr = saddr;
180         fl4->flowi4_tos = tos;
181         fl4->flowi4_proto = IPPROTO_GRE;
182         fl4->fl4_gre_key = gre_key;
183         return ip_route_output_key(net, fl4);
184 }
185 int ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
186                           u8 tos, struct net_device *dev,
187                           struct in_device *in_dev, u32 *itag);
188 int ip_route_input_noref(struct sk_buff *skb, __be32 dst, __be32 src,
189                          u8 tos, struct net_device *devin);
190 int ip_route_input_rcu(struct sk_buff *skb, __be32 dst, __be32 src,
191                        u8 tos, struct net_device *devin,
192                        struct fib_result *res);
193 
194 int ip_route_use_hint(struct sk_buff *skb, __be32 dst, __be32 src,
195                       u8 tos, struct net_device *devin,
196                       const struct sk_buff *hint);
197 
198 static inline int ip_route_input(struct sk_buff *skb, __be32 dst, __be32 src,
199                                  u8 tos, struct net_device *devin)
200 {
201         int err;
202 
203         rcu_read_lock();
204         err = ip_route_input_noref(skb, dst, src, tos, devin);
205         if (!err) {
206                 skb_dst_force(skb);
207                 if (!skb_dst(skb))
208                         err = -EINVAL;
209         }
210         rcu_read_unlock();
211 
212         return err;
213 }
214 
215 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu, int oif,
216                       u8 protocol);
217 void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu);
218 void ipv4_redirect(struct sk_buff *skb, struct net *net, int oif, u8 protocol);
219 void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk);
220 void ip_rt_send_redirect(struct sk_buff *skb);
221 
222 unsigned int inet_addr_type(struct net *net, __be32 addr);
223 unsigned int inet_addr_type_table(struct net *net, __be32 addr, u32 tb_id);
224 unsigned int inet_dev_addr_type(struct net *net, const struct net_device *dev,
225                                 __be32 addr);
226 unsigned int inet_addr_type_dev_table(struct net *net,
227                                       const struct net_device *dev,
228                                       __be32 addr);
229 void ip_rt_multicast_event(struct in_device *);
230 int ip_rt_ioctl(struct net *, unsigned int cmd, struct rtentry *rt);
231 void ip_rt_get_source(u8 *src, struct sk_buff *skb, struct rtable *rt);
232 struct rtable *rt_dst_alloc(struct net_device *dev,
233                              unsigned int flags, u16 type,
234                              bool nopolicy, bool noxfrm);
235 struct rtable *rt_dst_clone(struct net_device *dev, struct rtable *rt);
236 
237 struct in_ifaddr;
238 void fib_add_ifaddr(struct in_ifaddr *);
239 void fib_del_ifaddr(struct in_ifaddr *, struct in_ifaddr *);
240 void fib_modify_prefix_metric(struct in_ifaddr *ifa, u32 new_metric);
241 
242 void rt_add_uncached_list(struct rtable *rt);
243 void rt_del_uncached_list(struct rtable *rt);
244 
245 int fib_dump_info_fnhe(struct sk_buff *skb, struct netlink_callback *cb,
246                        u32 table_id, struct fib_info *fi,
247                        int *fa_index, int fa_start, unsigned int flags);
248 
249 static inline void ip_rt_put(struct rtable *rt)
250 {
251         /* dst_release() accepts a NULL parameter.
252          * We rely on dst being first structure in struct rtable
253          */
254         BUILD_BUG_ON(offsetof(struct rtable, dst) != 0);
255         dst_release(&rt->dst);
256 }
257 
258 #define IPTOS_RT_MASK   (IPTOS_TOS_MASK & ~3)
259 
260 extern const __u8 ip_tos2prio[16];
261 
262 static inline char rt_tos2priority(u8 tos)
263 {
264         return ip_tos2prio[IPTOS_TOS(tos)>>1];
265 }
266 
267 /* ip_route_connect() and ip_route_newports() work in tandem whilst
268  * binding a socket for a new outgoing connection.
269  *
270  * In order to use IPSEC properly, we must, in the end, have a
271  * route that was looked up using all available keys including source
272  * and destination ports.
273  *
274  * However, if a source port needs to be allocated (the user specified
275  * a wildcard source port) we need to obtain addressing information
276  * in order to perform that allocation.
277  *
278  * So ip_route_connect() looks up a route using wildcarded source and
279  * destination ports in the key, simply so that we can get a pair of
280  * addresses to use for port allocation.
281  *
282  * Later, once the ports are allocated, ip_route_newports() will make
283  * another route lookup if needed to make sure we catch any IPSEC
284  * rules keyed on the port information.
285  *
286  * The callers allocate the flow key on their stack, and must pass in
287  * the same flowi4 object to both the ip_route_connect() and the
288  * ip_route_newports() calls.
289  */
290 
291 static inline void ip_route_connect_init(struct flowi4 *fl4, __be32 dst, __be32 src,
292                                          u32 tos, int oif, u8 protocol,
293                                          __be16 sport, __be16 dport,
294                                          struct sock *sk)
295 {
296         __u8 flow_flags = 0;
297 
298         if (inet_sk(sk)->transparent)
299                 flow_flags |= FLOWI_FLAG_ANYSRC;
300 
301         flowi4_init_output(fl4, oif, sk->sk_mark, tos, RT_SCOPE_UNIVERSE,
302                            protocol, flow_flags, dst, src, dport, sport,
303                            sk->sk_uid);
304 }
305 
306 static inline struct rtable *ip_route_connect(struct flowi4 *fl4,
307                                               __be32 dst, __be32 src, u32 tos,
308                                               int oif, u8 protocol,
309                                               __be16 sport, __be16 dport,
310                                               struct sock *sk)
311 {
312         struct net *net = sock_net(sk);
313         struct rtable *rt;
314 
315         ip_route_connect_init(fl4, dst, src, tos, oif, protocol,
316                               sport, dport, sk);
317 
318         if (!dst || !src) {
319                 rt = __ip_route_output_key(net, fl4);
320                 if (IS_ERR(rt))
321                         return rt;
322                 ip_rt_put(rt);
323                 flowi4_update_output(fl4, oif, tos, fl4->daddr, fl4->saddr);
324         }
325         security_sk_classify_flow(sk, flowi4_to_flowi(fl4));
326         return ip_route_output_flow(net, fl4, sk);
327 }
328 
329 static inline struct rtable *ip_route_newports(struct flowi4 *fl4, struct rtable *rt,
330                                                __be16 orig_sport, __be16 orig_dport,
331                                                __be16 sport, __be16 dport,
332                                                struct sock *sk)
333 {
334         if (sport != orig_sport || dport != orig_dport) {
335                 fl4->fl4_dport = dport;
336                 fl4->fl4_sport = sport;
337                 ip_rt_put(rt);
338                 flowi4_update_output(fl4, sk->sk_bound_dev_if,
339                                      RT_CONN_FLAGS(sk), fl4->daddr,
340                                      fl4->saddr);
341                 security_sk_classify_flow(sk, flowi4_to_flowi(fl4));
342                 return ip_route_output_flow(sock_net(sk), fl4, sk);
343         }
344         return rt;
345 }
346 
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 
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 = net->ipv4.sysctl_ip_default_ttl;
364         return hoplimit;
365 }
366 
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, daddr);
373         if (unlikely(!neigh))
374                 neigh = __neigh_create(&arp_tbl, &daddr, dev, false);
375 
376         return neigh;
377 }
378 
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 

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