Re: [ 105/124] af_unix: dont send SCM_CREDENTIAL when dest socket is NULL

[Sven Joachim]

On 2013-04-03 00:11 +0200, Greg Kroah-Hartman wrote:

> 3.8-stable review patch.  If anyone has any objections, please let me know.

I'm seeing several complaints from udevd at boot in both 3.8.6-rc1 and
3.9-rc5: "udevd[56]: sender uid=65534, message ignored".  Reverting the
patch below on top of 3.8.6-rc1 fixes that.  I'm using udev version 175
here, and 65534 is the uid of user "nobody".

Cheers,
       Sven


> From: dingtianhong <dingtianhong@xxxxxxxxxx>
>
> [ Upstream commit 14134f6584212d585b310ce95428014b653dfaf6 ]
>
> SCM_SCREDENTIALS should apply to write() syscalls only either source or destination
> socket asserted SOCK_PASSCRED. The original implememtation in maybe_add_creds is wrong,
> and breaks several LSB testcases ( i.e. /tset/LSB.os/netowkr/recvfrom/T.recvfrom).
>
> Origionally-authored-by: Karel Srot <ksrot@xxxxxxxxxx>
> Signed-off-by: Ding Tianhong <dingtianhong@xxxxxxxxxx>
> Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
>  net/unix/af_unix.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> --- a/net/unix/af_unix.c
> +++ b/net/unix/af_unix.c
> @@ -1414,8 +1414,8 @@ static void maybe_add_creds(struct sk_bu
>  	if (UNIXCB(skb).cred)
>  		return;
>  	if (test_bit(SOCK_PASSCRED, &sock->flags) ||
> -	    !other->sk_socket ||
> -	    test_bit(SOCK_PASSCRED, &other->sk_socket->flags)) {
> +	    (other->sk_socket &&
> +	    test_bit(SOCK_PASSCRED, &other->sk_socket->flags))) {
>  		UNIXCB(skb).pid  = get_pid(task_tgid(current));
>  		UNIXCB(skb).cred = get_current_cred();
>  	}
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