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a904a0693c
Historically linux tried to stick to RFC 791, 1122, 2003
for IPv4 ID field generation.
RFC 6864 made clear that no matter how hard we try,
we can not ensure unicity of IP ID within maximum
lifetime for all datagrams with a given source
address/destination address/protocol tuple.
Linux uses a per socket inet generator (inet_id), initialized
at connection startup with a XOR of 'jiffies' and other
fields that appear clear on the wire.
Thiemo Nagel pointed that this strategy is a privacy
concern as this provides 16 bits of entropy to fingerprint
devices.
Let's switch to a random starting point, this is just as
good as far as RFC 6864 is concerned and does not leak
anything critical.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Thiemo Nagel <tnagel@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
130 lines
3.1 KiB
C
130 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* common UDP/RAW code
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* Linux INET implementation
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*
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* Authors:
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* Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
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*/
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#include <linux/types.h>
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#include <linux/module.h>
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#include <linux/ip.h>
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#include <linux/in.h>
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#include <net/ip.h>
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#include <net/sock.h>
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#include <net/route.h>
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#include <net/tcp_states.h>
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#include <net/sock_reuseport.h>
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int __ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
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{
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struct inet_sock *inet = inet_sk(sk);
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struct sockaddr_in *usin = (struct sockaddr_in *) uaddr;
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struct flowi4 *fl4;
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struct rtable *rt;
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__be32 saddr;
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int oif;
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int err;
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if (addr_len < sizeof(*usin))
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return -EINVAL;
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if (usin->sin_family != AF_INET)
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return -EAFNOSUPPORT;
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sk_dst_reset(sk);
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oif = sk->sk_bound_dev_if;
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saddr = inet->inet_saddr;
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if (ipv4_is_multicast(usin->sin_addr.s_addr)) {
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if (!oif || netif_index_is_l3_master(sock_net(sk), oif))
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oif = inet->mc_index;
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if (!saddr)
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saddr = inet->mc_addr;
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}
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fl4 = &inet->cork.fl.u.ip4;
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rt = ip_route_connect(fl4, usin->sin_addr.s_addr, saddr,
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RT_CONN_FLAGS(sk), oif,
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sk->sk_protocol,
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inet->inet_sport, usin->sin_port, sk);
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if (IS_ERR(rt)) {
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err = PTR_ERR(rt);
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if (err == -ENETUNREACH)
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IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
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goto out;
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}
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if ((rt->rt_flags & RTCF_BROADCAST) && !sock_flag(sk, SOCK_BROADCAST)) {
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ip_rt_put(rt);
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err = -EACCES;
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goto out;
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}
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if (!inet->inet_saddr)
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inet->inet_saddr = fl4->saddr; /* Update source address */
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if (!inet->inet_rcv_saddr) {
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inet->inet_rcv_saddr = fl4->saddr;
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if (sk->sk_prot->rehash)
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sk->sk_prot->rehash(sk);
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}
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inet->inet_daddr = fl4->daddr;
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inet->inet_dport = usin->sin_port;
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reuseport_has_conns(sk, true);
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sk->sk_state = TCP_ESTABLISHED;
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sk_set_txhash(sk);
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inet->inet_id = prandom_u32();
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sk_dst_set(sk, &rt->dst);
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err = 0;
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out:
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return err;
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}
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EXPORT_SYMBOL(__ip4_datagram_connect);
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int ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
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{
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int res;
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lock_sock(sk);
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res = __ip4_datagram_connect(sk, uaddr, addr_len);
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release_sock(sk);
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return res;
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}
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EXPORT_SYMBOL(ip4_datagram_connect);
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/* Because UDP xmit path can manipulate sk_dst_cache without holding
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* socket lock, we need to use sk_dst_set() here,
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* even if we own the socket lock.
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*/
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void ip4_datagram_release_cb(struct sock *sk)
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{
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const struct inet_sock *inet = inet_sk(sk);
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const struct ip_options_rcu *inet_opt;
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__be32 daddr = inet->inet_daddr;
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struct dst_entry *dst;
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struct flowi4 fl4;
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struct rtable *rt;
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rcu_read_lock();
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dst = __sk_dst_get(sk);
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if (!dst || !dst->obsolete || dst->ops->check(dst, 0)) {
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rcu_read_unlock();
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return;
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}
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inet_opt = rcu_dereference(inet->inet_opt);
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if (inet_opt && inet_opt->opt.srr)
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daddr = inet_opt->opt.faddr;
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rt = ip_route_output_ports(sock_net(sk), &fl4, sk, daddr,
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inet->inet_saddr, inet->inet_dport,
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inet->inet_sport, sk->sk_protocol,
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RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
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dst = !IS_ERR(rt) ? &rt->dst : NULL;
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sk_dst_set(sk, dst);
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rcu_read_unlock();
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}
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EXPORT_SYMBOL_GPL(ip4_datagram_release_cb);
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