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 #include <net/sock_reuseport.h>
  19
  20 int __ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
  21 {
  22         struct inet_sock *inet = inet_sk(sk);
  23         struct sockaddr_in *usin = (struct sockaddr_in *) uaddr;
  24         struct flowi4 *fl4;
  25         struct rtable *rt;
  26         __be32 saddr;
  27         int oif;
  28         int err;
  29
  30
  31         if (addr_len < sizeof(*usin))
  32                 return -EINVAL;
  33
  34         if (usin->sin_family != AF_INET)
  35                 return -EAFNOSUPPORT;
  36
  37         sk_dst_reset(sk);
  38
  39         oif = sk->sk_bound_dev_if;
  40         saddr = inet->inet_saddr;
  41         if (ipv4_is_multicast(usin->sin_addr.s_addr)) {
  42                 if (!oif || netif_index_is_l3_master(sock_net(sk), oif))
  43                         oif = inet->mc_index;
  44                 if (!saddr)
  45                         saddr = inet->mc_addr;
  46         }
  47         fl4 = &inet->cork.fl.u.ip4;
  48         rt = ip_route_connect(fl4, usin->sin_addr.s_addr, saddr,
  49                               RT_CONN_FLAGS(sk), oif,
  50                               sk->sk_protocol,
  51                               inet->inet_sport, usin->sin_port, sk);
  52         if (IS_ERR(rt)) {
  53                 err = PTR_ERR(rt);
  54                 if (err == -ENETUNREACH)
  55                         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
  56                 goto out;
  57         }
  58
  59         if ((rt->rt_flags & RTCF_BROADCAST) && !sock_flag(sk, SOCK_BROADCAST)) {
  60                 ip_rt_put(rt);
  61                 err = -EACCES;
  62                 goto out;
  63         }
  64         if (!inet->inet_saddr)
  65                 inet->inet_saddr = fl4->saddr;  /* Update source address */
  66         if (!inet->inet_rcv_saddr) {
  67                 inet->inet_rcv_saddr = fl4->saddr;
  68                 if (sk->sk_prot->rehash)
  69                         sk->sk_prot->rehash(sk);
  70         }
  71         inet->inet_daddr = fl4->daddr;
  72         inet->inet_dport = usin->sin_port;
  73         reuseport_has_conns(sk, true);
  74         sk->sk_state = TCP_ESTABLISHED;
  75         sk_set_txhash(sk);
  76         inet->inet_id = prandom_u32();
  77
  78         sk_dst_set(sk, &rt->dst);
  79         err = 0;
  80 out:
  81         return err;
  82 }
  83 EXPORT_SYMBOL(__ip4_datagram_connect);
  84
  85 int ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
  86 {
  87         int res;
  88
  89         lock_sock(sk);
  90         res = __ip4_datagram_connect(sk, uaddr, addr_len);
  91         release_sock(sk);
  92         return res;
  93 }
  94 EXPORT_SYMBOL(ip4_datagram_connect);
  95
  96 /* Because UDP xmit path can manipulate sk_dst_cache without holding
  97  * socket lock, we need to use sk_dst_set() here,
  98  * even if we own the socket lock.
  99  */
 100 void ip4_datagram_release_cb(struct sock *sk)
 101 {
 102         const struct inet_sock *inet = inet_sk(sk);
 103         const struct ip_options_rcu *inet_opt;
 104         __be32 daddr = inet->inet_daddr;
 105         struct dst_entry *dst;
 106         struct flowi4 fl4;
 107         struct rtable *rt;
 108
 109         rcu_read_lock();
 110
 111         dst = __sk_dst_get(sk);
 112         if (!dst || !dst->obsolete || dst->ops->check(dst, 0)) {
 113                 rcu_read_unlock();
 114                 return;
 115         }
 116         inet_opt = rcu_dereference(inet->inet_opt);
 117         if (inet_opt && inet_opt->opt.srr)
 118                 daddr = inet_opt->opt.faddr;
 119         rt = ip_route_output_ports(sock_net(sk), &fl4, sk, daddr,
 120                                    inet->inet_saddr, inet->inet_dport,
 121                                    inet->inet_sport, sk->sk_protocol,
 122                                    RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
 123
 124         dst = !IS_ERR(rt) ? &rt->dst : NULL;
 125         sk_dst_set(sk, dst);
 126
 127         rcu_read_unlock();
 128 }
 129 EXPORT_SYMBOL_GPL(ip4_datagram_release_cb);