Commit d66954a0 authored Apr 11, 2013 by Dmitry Popov Committed by David S. Miller Apr 11, 2013

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: Dmitry Popov <dp@highloadlab.com>
Signed-off-by: David 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);

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