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    Subject[ review 12/84] Fix error queue socket lookup in ipv6
    From: Dmitry Butskoy <>

    [IPV6]: MSG_ERRQUEUE messages do not pass to connected raw sockets

    From: Dmitry Butskoy <>

    Taken from

    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

    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);
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      Last update: 2007-08-07 22:55    [W:0.033 / U:0.548 seconds]
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