Re: [patch] net/unix: do not forget to autobind in standard case

[Eric Dumazet <eric.dumazet@gmail.com>]

Le samedi 25 décembre 2010 à 01:08 +0100, Jan Engelhardt a écrit :
> parent 67514fc40bbec857018cbc689d440282b75551db (v2.6.37-rc1-229-g67514fc)
> commit 973bdc63c6aba703dd7b62a6ec7ae4bab7847731
> Author: Jan Engelhardt <jengelh@medozas.de>
> Date:   Sat Dec 25 00:50:59 2010 +0100
> 
> net/unix: do not forget to autobind in standard case
> 
> A program using recvmsg on an AF_LOCAL datagram socket does not
> receive the peer's address when the remote has not issued a bind. This
> makes it impossible to send messages back. (But the same _does_ work
> in IP.) The cause for this is because autobinding was only done when
> credential passing was requested.
> 

It would be good you did some research and tell us why current code
tests SOCK_PASSCRED

There must be a reason this restrictive code is here, dont you think ?

> --->8---
> 
> Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
> ---
>  net/unix/af_unix.c |   10 ++++------
>  1 files changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> index 7ff31c6..945797c 100644
> --- a/net/unix/af_unix.c
> +++ b/net/unix/af_unix.c
> @@ -964,8 +964,8 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
>  			goto out;
>  		alen = err;
>  
> -		if (test_bit(SOCK_PASSCRED, &sock->flags) &&
> -		    !unix_sk(sk)->addr && (err = unix_autobind(sock)) != 0)
> +		if (unix_sk(sk)->addr == NULL &&
> +		    (err = unix_autobind(sock)) != 0)
>  			goto out;
>  
>  restart:
> @@ -1063,8 +1063,7 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
>  		goto out;
>  	addr_len = err;
>  
> -	if (test_bit(SOCK_PASSCRED, &sock->flags) && !u->addr &&
> -	    (err = unix_autobind(sock)) != 0)
> +	if (u->addr == NULL && (err = unix_autobind(sock)) != 0)
>  		goto out;
>  
>  	timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);
> @@ -1419,8 +1418,7 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
>  			goto out;
>  	}
>  
> -	if (test_bit(SOCK_PASSCRED, &sock->flags) && !u->addr
> -	    && (err = unix_autobind(sock)) != 0)
> +	if (u->addr == NULL && (err = unix_autobind(sock)) != 0)
>  		goto out;
>  
>  	err = -EMSGSIZE;