LXR linux/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
  20int __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;
  80out:
  81        return err;
  82}
  83EXPORT_SYMBOL(__ip4_datagram_connect);
  84
  85int 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}
  94EXPORT_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 */
 100void 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}
 129EXPORT_SYMBOL_GPL(ip4_datagram_release_cb);
 130