From: Dmitry Butskoy [IPV6]: MSG_ERRQUEUE messages do not pass to connected raw sockets From: Dmitry Butskoy Taken from http://bugzilla.kernel.org/show_bug.cgi?id=8747 Problem Description: It is related to the possibility to obtain MSG_ERRQUEUE messages from the udp and raw sockets, both connected and unconnected. There is a little typo in net/ipv6/icmp.c code, which prevents such messages to be delivered to the errqueue of the correspond raw socket, when the socket is CONNECTED. The typo is due to swap of local/remote addresses. Consider __raw_v6_lookup() function from net/ipv6/raw.c. When a raw socket is looked up usual way, it is something like: sk = __raw_v6_lookup(sk, nexthdr, daddr, saddr, IP6CB(skb)->iif); where "daddr" is a destination address of the incoming packet (IOW our local address), "saddr" is a source address of the incoming packet (the remote end). But when the raw socket is looked up for some icmp error report, in net/ipv6/icmp.c:icmpv6_notify() , daddr/saddr are obtained from the echoed fragment of the "bad" packet, i.e. "daddr" is the original destination address of that packet, "saddr" is our local address. Hence, for icmpv6_notify() must use "saddr, daddr" in its arguments, not "daddr, saddr" ... Steps to reproduce: Create some raw socket, connect it to an address, and cause some error situation: f.e. set ttl=1 where the remote address is more than 1 hop to reach. Set IPV6_RECVERR . Then send something and wait for the error (f.e. poll() with POLLERR|POLLIN). You should receive "time exceeded" icmp message (because of "ttl=1"), but the socket do not receive it. If you do not connect your raw socket, you will receive MSG_ERRQUEUE successfully. (The reason is that for unconnected socket there are no actual checks for local/remote addresses). Signed-off-by: Andrew Morton Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv6/icmp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/ipv6/icmp.c +++ b/net/ipv6/icmp.c @@ -604,7 +604,7 @@ static void icmpv6_notify(struct sk_buff read_lock(&raw_v6_lock); if ((sk = sk_head(&raw_v6_htable[hash])) != NULL) { - while((sk = __raw_v6_lookup(sk, nexthdr, daddr, saddr, + while ((sk = __raw_v6_lookup(sk, nexthdr, saddr, daddr, IP6CB(skb)->iif))) { rawv6_err(sk, skb, NULL, type, code, inner_offset, info); sk = sk_next(sk); -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/