net/ipv4/datagram.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      common UDP/RAW code
   4  *      Linux INET implementation
   5  *
   6  * Authors:
   7  *      Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
   8  */
   9
  10 #include <linux/types.h>
  11 #include <linux/module.h>
  12 #include <linux/ip.h>
  13 #include <linux/in.h>
  14 #include <net/ip.h>
  15 #include <net/sock.h>
  16 #include <net/route.h>
  17 #include <net/tcp_states.h>
  18
  19 int __ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
  20 {
  21         struct inet_sock *inet = inet_sk(sk);
  22         struct sockaddr_in *usin = (struct sockaddr_in *) uaddr;
  23         struct flowi4 *fl4;
  24         struct rtable *rt;
  25         __be32 saddr;
  26         int oif;
  27         int err;
  28
  29
  30         if (addr_len < sizeof(*usin))
  31                 return -EINVAL;
  32
  33         if (usin->sin_family != AF_INET)
  34                 return -EAFNOSUPPORT;
  35
  36         sk_dst_reset(sk);
  37
  38         oif = sk->sk_bound_dev_if;
  39         saddr = inet->inet_saddr;
  40         if (ipv4_is_multicast(usin->sin_addr.s_addr)) {
  41                 if (!oif || netif_index_is_l3_master(sock_net(sk), oif))
  42                         oif = inet->mc_index;
  43                 if (!saddr)
  44                         saddr = inet->mc_addr;
  45         }
  46         fl4 = &inet->cork.fl.u.ip4;
  47         rt = ip_route_connect(fl4, usin->sin_addr.s_addr, saddr,
  48                               RT_CONN_FLAGS(sk), oif,
  49                               sk->sk_protocol,
  50                               inet->inet_sport, usin->sin_port, sk);
  51         if (IS_ERR(rt)) {
  52                 err = PTR_ERR(rt);
  53                 if (err == -ENETUNREACH)
  54                         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
  55                 goto out;
  56         }
  57
  58         if ((rt->rt_flags & RTCF_BROADCAST) && !sock_flag(sk, SOCK_BROADCAST)) {
  59                 ip_rt_put(rt);
  60                 err = -EACCES;
  61                 goto out;
  62         }
  63         if (!inet->inet_saddr)
  64                 inet->inet_saddr = fl4->saddr;  /* Update source address */
  65         if (!inet->inet_rcv_saddr) {
  66                 inet->inet_rcv_saddr = fl4->saddr;
  67                 if (sk->sk_prot->rehash)
  68                         sk->sk_prot->rehash(sk);
  69         }
  70         inet->inet_daddr = fl4->daddr;
  71         inet->inet_dport = usin->sin_port;
  72         sk->sk_state = TCP_ESTABLISHED;
  73         sk_set_txhash(sk);
  74         inet->inet_id = jiffies;
  75
  76         sk_dst_set(sk, &rt->dst);
  77         err = 0;
  78 out:
  79         return err;
  80 }
  81 EXPORT_SYMBOL(__ip4_datagram_connect);
  82
  83 int ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
  84 {
  85         int res;
  86
  87         lock_sock(sk);
  88         res = __ip4_datagram_connect(sk, uaddr, addr_len);
  89         release_sock(sk);
  90         return res;
  91 }
  92 EXPORT_SYMBOL(ip4_datagram_connect);
  93
  94 /* Because UDP xmit path can manipulate sk_dst_cache without holding
  95  * socket lock, we need to use sk_dst_set() here,
  96  * even if we own the socket lock.
  97  */
  98 void ip4_datagram_release_cb(struct sock *sk)
  99 {
 100         const struct inet_sock *inet = inet_sk(sk);
 101         const struct ip_options_rcu *inet_opt;
 102         __be32 daddr = inet->inet_daddr;
 103         struct dst_entry *dst;
 104         struct flowi4 fl4;
 105         struct rtable *rt;
 106
 107         rcu_read_lock();
 108
 109         dst = __sk_dst_get(sk);
 110         if (!dst || !dst->obsolete || dst->ops->check(dst, 0)) {
 111                 rcu_read_unlock();
 112                 return;
 113         }
 114         inet_opt = rcu_dereference(inet->inet_opt);
 115         if (inet_opt && inet_opt->opt.srr)
 116                 daddr = inet_opt->opt.faddr;
 117         rt = ip_route_output_ports(sock_net(sk), &fl4, sk, daddr,
 118                                    inet->inet_saddr, inet->inet_dport,
 119                                    inet->inet_sport, sk->sk_protocol,
 120                                    RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
 121
 122         dst = !IS_ERR(rt) ? &rt->dst : NULL;
 123         sk_dst_set(sk, dst);
 124
 125         rcu_read_unlock();
 126 }
 127 EXPORT_SYMBOL_GPL(ip4_datagram_release_cb);