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_gw_family;
  57
  58         int                     rt_iif;
  59
  60         /* Info on neighbour */
  61         union {
  62                 __be32          rt_gw4;
  63                 struct in6_addr rt_gw6;
  64         };
  65
  66         /* Miscellaneous cached information */
  67         u32                     rt_mtu_locked:1,
  68                                 rt_pmtu:31;
  69
  70         struct list_head        rt_uncached;
  71         struct uncached_list    *rt_uncached_list;
  72 };
  73
  74 static inline bool rt_is_input_route(const struct rtable *rt)
  75 {
  76         return rt->rt_is_input != 0;
  77 }
  78
  79 static inline bool rt_is_output_route(const struct rtable *rt)
  80 {
  81         return rt->rt_is_input == 0;
  82 }
  83
  84 static inline __be32 rt_nexthop(const struct rtable *rt, __be32 daddr)
  85 {
  86         if (rt->rt_gw_family == AF_INET)
  87                 return rt->rt_gw4;
  88         return daddr;
  89 }
  90
  91 struct ip_rt_acct {
  92         __u32   o_bytes;
  93         __u32   o_packets;
  94         __u32   i_bytes;
  95         __u32   i_packets;
  96 };
  97
  98 struct rt_cache_stat {
  99         unsigned int in_slow_tot;
 100         unsigned int in_slow_mc;
 101         unsigned int in_no_route;
 102         unsigned int in_brd;
 103         unsigned int in_martian_dst;
 104         unsigned int in_martian_src;
 105         unsigned int out_slow_tot;
 106         unsigned int out_slow_mc;
 107 };
 108
 109 extern struct ip_rt_acct __percpu *ip_rt_acct;
 110
 111 struct in_device;
 112
 113 int ip_rt_init(void);
 114 void rt_cache_flush(struct net *net);
 115 void rt_flush_dev(struct net_device *dev);
 116 struct rtable *ip_route_output_key_hash(struct net *net, struct flowi4 *flp,
 117                                         const struct sk_buff *skb);
 118 struct rtable *ip_route_output_key_hash_rcu(struct net *net, struct flowi4 *flp,
 119                                             struct fib_result *res,
 120                                             const struct sk_buff *skb);
 121
 122 static inline struct rtable *__ip_route_output_key(struct net *net,
 123                                                    struct flowi4 *flp)
 124 {
 125         return ip_route_output_key_hash(net, flp, NULL);
 126 }
 127
 128 struct rtable *ip_route_output_flow(struct net *, struct flowi4 *flp,
 129                                     const struct sock *sk);
 130 struct dst_entry *ipv4_blackhole_route(struct net *net,
 131                                        struct dst_entry *dst_orig);
 132
 133 static inline struct rtable *ip_route_output_key(struct net *net, struct flowi4 *flp)
 134 {
 135         return ip_route_output_flow(net, flp, NULL);
 136 }
 137
 138 static inline struct rtable *ip_route_output(struct net *net, __be32 daddr,
 139                                              __be32 saddr, u8 tos, int oif)
 140 {
 141         struct flowi4 fl4 = {
 142                 .flowi4_oif = oif,
 143                 .flowi4_tos = tos,
 144                 .daddr = daddr,
 145                 .saddr = saddr,
 146         };
 147         return ip_route_output_key(net, &fl4);
 148 }
 149
 150 static inline struct rtable *ip_route_output_ports(struct net *net, struct flowi4 *fl4,
 151                                                    struct sock *sk,
 152                                                    __be32 daddr, __be32 saddr,
 153                                                    __be16 dport, __be16 sport,
 154                                                    __u8 proto, __u8 tos, int oif)
 155 {
 156         flowi4_init_output(fl4, oif, sk ? sk->sk_mark : 0, tos,
 157                            RT_SCOPE_UNIVERSE, proto,
 158                            sk ? inet_sk_flowi_flags(sk) : 0,
 159                            daddr, saddr, dport, sport, sock_net_uid(net, sk));
 160         if (sk)
 161                 security_sk_classify_flow(sk, flowi4_to_flowi(fl4));
 162         return ip_route_output_flow(net, fl4, sk);
 163 }
 164
 165 static inline struct rtable *ip_route_output_gre(struct net *net, struct flowi4 *fl4,
 166                                                  __be32 daddr, __be32 saddr,
 167                                                  __be32 gre_key, __u8 tos, int oif)
 168 {
 169         memset(fl4, 0, sizeof(*fl4));
 170         fl4->flowi4_oif = oif;
 171         fl4->daddr = daddr;
 172         fl4->saddr = saddr;
 173         fl4->flowi4_tos = tos;
 174         fl4->flowi4_proto = IPPROTO_GRE;
 175         fl4->fl4_gre_key = gre_key;
 176         return ip_route_output_key(net, fl4);
 177 }
 178 int ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 179                           u8 tos, struct net_device *dev,
 180                           struct in_device *in_dev, u32 *itag);
 181 int ip_route_input_noref(struct sk_buff *skb, __be32 dst, __be32 src,
 182                          u8 tos, struct net_device *devin);
 183 int ip_route_input_rcu(struct sk_buff *skb, __be32 dst, __be32 src,
 184                        u8 tos, struct net_device *devin,
 185                        struct fib_result *res);
 186
 187 static inline int ip_route_input(struct sk_buff *skb, __be32 dst, __be32 src,
 188                                  u8 tos, struct net_device *devin)
 189 {
 190         int err;
 191
 192         rcu_read_lock();
 193         err = ip_route_input_noref(skb, dst, src, tos, devin);
 194         if (!err) {
 195                 skb_dst_force(skb);
 196                 if (!skb_dst(skb))
 197                         err = -EINVAL;
 198         }
 199         rcu_read_unlock();
 200
 201         return err;
 202 }
 203
 204 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu, int oif,
 205                       u8 protocol);
 206 void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu);
 207 void ipv4_redirect(struct sk_buff *skb, struct net *net, int oif, u8 protocol);
 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 struct rtable *rt_dst_clone(struct net_device *dev, struct rtable *rt);
 225
 226 struct in_ifaddr;
 227 void fib_add_ifaddr(struct in_ifaddr *);
 228 void fib_del_ifaddr(struct in_ifaddr *, struct in_ifaddr *);
 229 void fib_modify_prefix_metric(struct in_ifaddr *ifa, u32 new_metric);
 230
 231 void rt_add_uncached_list(struct rtable *rt);
 232 void rt_del_uncached_list(struct rtable *rt);
 233
 234 int fib_dump_info_fnhe(struct sk_buff *skb, struct netlink_callback *cb,
 235                        u32 table_id, struct fib_info *fi,
 236                        int *fa_index, int fa_start, unsigned int flags);
 237
 238 static inline void ip_rt_put(struct rtable *rt)
 239 {
 240         /* dst_release() accepts a NULL parameter.
 241          * We rely on dst being first structure in struct rtable
 242          */
 243         BUILD_BUG_ON(offsetof(struct rtable, dst) != 0);
 244         dst_release(&rt->dst);
 245 }
 246
 247 #define IPTOS_RT_MASK   (IPTOS_TOS_MASK & ~3)
 248
 249 extern const __u8 ip_tos2prio[16];
 250
 251 static inline char rt_tos2priority(u8 tos)
 252 {
 253         return ip_tos2prio[IPTOS_TOS(tos)>>1];
 254 }
 255
 256 /* ip_route_connect() and ip_route_newports() work in tandem whilst
 257  * binding a socket for a new outgoing connection.
 258  *
 259  * In order to use IPSEC properly, we must, in the end, have a
 260  * route that was looked up using all available keys including source
 261  * and destination ports.
 262  *
 263  * However, if a source port needs to be allocated (the user specified
 264  * a wildcard source port) we need to obtain addressing information
 265  * in order to perform that allocation.
 266  *
 267  * So ip_route_connect() looks up a route using wildcarded source and
 268  * destination ports in the key, simply so that we can get a pair of
 269  * addresses to use for port allocation.
 270  *
 271  * Later, once the ports are allocated, ip_route_newports() will make
 272  * another route lookup if needed to make sure we catch any IPSEC
 273  * rules keyed on the port information.
 274  *
 275  * The callers allocate the flow key on their stack, and must pass in
 276  * the same flowi4 object to both the ip_route_connect() and the
 277  * ip_route_newports() calls.
 278  */
 279
 280 static inline void ip_route_connect_init(struct flowi4 *fl4, __be32 dst, __be32 src,
 281                                          u32 tos, int oif, u8 protocol,
 282                                          __be16 sport, __be16 dport,
 283                                          struct sock *sk)
 284 {
 285         __u8 flow_flags = 0;
 286
 287         if (inet_sk(sk)->transparent)
 288                 flow_flags |= FLOWI_FLAG_ANYSRC;
 289
 290         flowi4_init_output(fl4, oif, sk->sk_mark, tos, RT_SCOPE_UNIVERSE,
 291                            protocol, flow_flags, dst, src, dport, sport,
 292                            sk->sk_uid);
 293 }
 294
 295 static inline struct rtable *ip_route_connect(struct flowi4 *fl4,
 296                                               __be32 dst, __be32 src, u32 tos,
 297                                               int oif, u8 protocol,
 298                                               __be16 sport, __be16 dport,
 299                                               struct sock *sk)
 300 {
 301         struct net *net = sock_net(sk);
 302         struct rtable *rt;
 303
 304         ip_route_connect_init(fl4, dst, src, tos, oif, protocol,
 305                               sport, dport, sk);
 306
 307         if (!dst || !src) {
 308                 rt = __ip_route_output_key(net, fl4);
 309                 if (IS_ERR(rt))
 310                         return rt;
 311                 ip_rt_put(rt);
 312                 flowi4_update_output(fl4, oif, tos, fl4->daddr, fl4->saddr);
 313         }
 314         security_sk_classify_flow(sk, flowi4_to_flowi(fl4));
 315         return ip_route_output_flow(net, fl4, sk);
 316 }
 317
 318 static inline struct rtable *ip_route_newports(struct flowi4 *fl4, struct rtable *rt,
 319                                                __be16 orig_sport, __be16 orig_dport,
 320                                                __be16 sport, __be16 dport,
 321                                                struct sock *sk)
 322 {
 323         if (sport != orig_sport || dport != orig_dport) {
 324                 fl4->fl4_dport = dport;
 325                 fl4->fl4_sport = sport;
 326                 ip_rt_put(rt);
 327                 flowi4_update_output(fl4, sk->sk_bound_dev_if,
 328                                      RT_CONN_FLAGS(sk), fl4->daddr,
 329                                      fl4->saddr);
 330                 security_sk_classify_flow(sk, flowi4_to_flowi(fl4));
 331                 return ip_route_output_flow(sock_net(sk), fl4, sk);
 332         }
 333         return rt;
 334 }
 335
 336 static inline int inet_iif(const struct sk_buff *skb)
 337 {
 338         struct rtable *rt = skb_rtable(skb);
 339
 340         if (rt && rt->rt_iif)
 341                 return rt->rt_iif;
 342
 343         return skb->skb_iif;
 344 }
 345
 346 static inline int ip4_dst_hoplimit(const struct dst_entry *dst)
 347 {
 348         int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
 349         struct net *net = dev_net(dst->dev);
 350
 351         if (hoplimit == 0)
 352                 hoplimit = net->ipv4.sysctl_ip_default_ttl;
 353         return hoplimit;
 354 }
 355
 356 static inline struct neighbour *ip_neigh_gw4(struct net_device *dev,
 357                                              __be32 daddr)
 358 {
 359         struct neighbour *neigh;
 360
 361         neigh = __ipv4_neigh_lookup_noref(dev, daddr);
 362         if (unlikely(!neigh))
 363                 neigh = __neigh_create(&arp_tbl, &daddr, dev, false);
 364
 365         return neigh;
 366 }
 367
 368 static inline struct neighbour *ip_neigh_for_gw(struct rtable *rt,
 369                                                 struct sk_buff *skb,
 370                                                 bool *is_v6gw)
 371 {
 372         struct net_device *dev = rt->dst.dev;
 373         struct neighbour *neigh;
 374
 375         if (likely(rt->rt_gw_family == AF_INET)) {
 376                 neigh = ip_neigh_gw4(dev, rt->rt_gw4);
 377         } else if (rt->rt_gw_family == AF_INET6) {
 378                 neigh = ip_neigh_gw6(dev, &rt->rt_gw6);
 379                 *is_v6gw = true;
 380         } else {
 381                 neigh = ip_neigh_gw4(dev, ip_hdr(skb)->daddr);
 382         }
 383         return neigh;
 384 }
 385
 386 #endif  /* _ROUTE_H */