xref: /openbmc/linux/net/ipv4/datagram.c (revision e2f1cf25)
1 /*
2  *	common UDP/RAW code
3  *	Linux INET implementation
4  *
5  * Authors:
6  * 	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
7  *
8  * 	This program is free software; you can redistribute it and/or
9  * 	modify it under the terms of the GNU General Public License
10  * 	as published by the Free Software Foundation; either version
11  * 	2 of the License, or (at your option) any later version.
12  */
13 
14 #include <linux/types.h>
15 #include <linux/module.h>
16 #include <linux/ip.h>
17 #include <linux/in.h>
18 #include <net/ip.h>
19 #include <net/sock.h>
20 #include <net/route.h>
21 #include <net/tcp_states.h>
22 
23 int __ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
24 {
25 	struct inet_sock *inet = inet_sk(sk);
26 	struct sockaddr_in *usin = (struct sockaddr_in *) uaddr;
27 	struct flowi4 *fl4;
28 	struct rtable *rt;
29 	__be32 saddr;
30 	int oif;
31 	int err;
32 
33 
34 	if (addr_len < sizeof(*usin))
35 		return -EINVAL;
36 
37 	if (usin->sin_family != AF_INET)
38 		return -EAFNOSUPPORT;
39 
40 	sk_dst_reset(sk);
41 
42 	oif = sk->sk_bound_dev_if;
43 	saddr = inet->inet_saddr;
44 	if (ipv4_is_multicast(usin->sin_addr.s_addr)) {
45 		if (!oif)
46 			oif = inet->mc_index;
47 		if (!saddr)
48 			saddr = inet->mc_addr;
49 	}
50 	fl4 = &inet->cork.fl.u.ip4;
51 	rt = ip_route_connect(fl4, usin->sin_addr.s_addr, saddr,
52 			      RT_CONN_FLAGS(sk), oif,
53 			      sk->sk_protocol,
54 			      inet->inet_sport, usin->sin_port, sk);
55 	if (IS_ERR(rt)) {
56 		err = PTR_ERR(rt);
57 		if (err == -ENETUNREACH)
58 			IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
59 		goto out;
60 	}
61 
62 	if ((rt->rt_flags & RTCF_BROADCAST) && !sock_flag(sk, SOCK_BROADCAST)) {
63 		ip_rt_put(rt);
64 		err = -EACCES;
65 		goto out;
66 	}
67 	if (!inet->inet_saddr)
68 		inet->inet_saddr = fl4->saddr;	/* Update source address */
69 	if (!inet->inet_rcv_saddr) {
70 		inet->inet_rcv_saddr = fl4->saddr;
71 		if (sk->sk_prot->rehash)
72 			sk->sk_prot->rehash(sk);
73 	}
74 	inet->inet_daddr = fl4->daddr;
75 	inet->inet_dport = usin->sin_port;
76 	sk->sk_state = TCP_ESTABLISHED;
77 	inet_set_txhash(sk);
78 	inet->inet_id = jiffies;
79 
80 	sk_dst_set(sk, &rt->dst);
81 	err = 0;
82 out:
83 	return err;
84 }
85 EXPORT_SYMBOL(__ip4_datagram_connect);
86 
87 int ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
88 {
89 	int res;
90 
91 	lock_sock(sk);
92 	res = __ip4_datagram_connect(sk, uaddr, addr_len);
93 	release_sock(sk);
94 	return res;
95 }
96 EXPORT_SYMBOL(ip4_datagram_connect);
97 
98 /* Because UDP xmit path can manipulate sk_dst_cache without holding
99  * socket lock, we need to use sk_dst_set() here,
100  * even if we own the socket lock.
101  */
102 void ip4_datagram_release_cb(struct sock *sk)
103 {
104 	const struct inet_sock *inet = inet_sk(sk);
105 	const struct ip_options_rcu *inet_opt;
106 	__be32 daddr = inet->inet_daddr;
107 	struct dst_entry *dst;
108 	struct flowi4 fl4;
109 	struct rtable *rt;
110 
111 	rcu_read_lock();
112 
113 	dst = __sk_dst_get(sk);
114 	if (!dst || !dst->obsolete || dst->ops->check(dst, 0)) {
115 		rcu_read_unlock();
116 		return;
117 	}
118 	inet_opt = rcu_dereference(inet->inet_opt);
119 	if (inet_opt && inet_opt->opt.srr)
120 		daddr = inet_opt->opt.faddr;
121 	rt = ip_route_output_ports(sock_net(sk), &fl4, sk, daddr,
122 				   inet->inet_saddr, inet->inet_dport,
123 				   inet->inet_sport, sk->sk_protocol,
124 				   RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
125 
126 	dst = !IS_ERR(rt) ? &rt->dst : NULL;
127 	sk_dst_set(sk, dst);
128 
129 	rcu_read_unlock();
130 }
131 EXPORT_SYMBOL_GPL(ip4_datagram_release_cb);
132