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/in.h>
13 #include <net/ip.h>
14 #include <net/sock.h>
15 #include <net/route.h>
16 #include <net/tcp_states.h>
17 #include <net/sock_reuseport.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 = READ_ONCE(inet->mc_index);
43 if (!saddr)
44 saddr = READ_ONCE(inet->mc_addr);
45 } else if (!oif) {
46 oif = READ_ONCE(inet->uc_index);
47 }
48 fl4 = &inet->cork.fl.u.ip4;
49 rt = ip_route_connect(fl4, usin->sin_addr.s_addr, saddr, oif,
50 sk->sk_protocol, inet->inet_sport,
51 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_set(sk);
74 sk->sk_state = TCP_ESTABLISHED;
75 sk_set_txhash(sk);
76 atomic_set(&inet->inet_id, get_random_u16());
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 ip_sock_rt_tos(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);
130
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