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Commit d66954a0 authored by Dmitry Popov's avatar Dmitry Popov Committed by David S. Miller
Browse files

tcp: incoming connections might use wrong route under synflood 



There is a bug in cookie_v4_check (net/ipv4/syncookies.c):
	flowi4_init_output(&fl4, 0, sk->sk_mark, RT_CONN_FLAGS(sk),
			   RT_SCOPE_UNIVERSE, IPPROTO_TCP,
			   inet_sk_flowi_flags(sk),
			   (opt && opt->srr) ? opt->faddr : ireq->rmt_addr,
			   ireq->loc_addr, th->source, th->dest);

Here we do not respect sk->sk_bound_dev_if, therefore wrong dst_entry may be
taken. This dst_entry is used by new socket (get_cookie_sock ->
tcp_v4_syn_recv_sock), so its packets may take the wrong path.

Signed-off-by: default avatarDmitry Popov <dp@highloadlab.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent fe2971a0

net/ipv4/syncookies.c

+2 −2
Original line number Diff line number Diff line
@@ -349,8 +349,8 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, 
	 * hasn't changed since we received the original syn, but I see

	 * no easy way to do this.

	 */

	flowi4_init_output(&fl4, 0, sk->sk_mark, RT_CONN_FLAGS(sk),

			   RT_SCOPE_UNIVERSE, IPPROTO_TCP,

	flowi4_init_output(&fl4, sk->sk_bound_dev_if, sk->sk_mark,

			   RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE, IPPROTO_TCP,

			   inet_sk_flowi_flags(sk),

			   (opt && opt->srr) ? opt->faddr : ireq->rmt_addr,

			   ireq->loc_addr, th->source, th->dest);