include/net/route.h

   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 */