From: Petr Vorel <pvorel@suse.cz>
To: Michal Kubecek <mkubecek@suse.cz>,
"David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org, WANG Cong <xiyou.wangcong@gmail.com>,
Rainer Weikusat <rweikusat@mobileactivedefense.com>,
linux-kernel@vger.kernel.org, ltp@lists.linux.it,
Cyril Hrubis <chrubis@suse.cz>,
Junchi Chen <junchi.chen@intel.com>
Subject: Re: RFC: changed error code when binding unix socket twice
Date: Fri, 31 Aug 2018 13:14:36 +0200 [thread overview]
Message-ID: <20180831111436.GA23780@dell5510> (raw)
In-Reply-To: <20170630073448.GA9546@unicorn.suse.cz>
Hi,
> commit 0fb44559ffd6 ("af_unix: move unix_mknod() out of bindlock") moves
> the special file creation in unix_bind() before u->bindlock is taken in
> order to avoid an ABBA deadlock with do_splice(). As a side effect, it
> also moves the check for existence of the special file (which would
> result in -EADDRINUSE) before the check of u->addr (which would result
> in -EINVAL if socket is already bound). This means that the error
> returned for an attempt to bind a unix socket to the same path twice
> changed from -EINVAL to -EADDRINUSE with this commit.
> One way to restore the old error code is indicated below but before
> submitting it, I would like to ask if we need/want it.
> Pro:
> - in general, we do not want to change return code for given testcase
> - old error (-EINVAL) is consistent with AF_INET(6)
> Con:
> - both POSIX and Linux man page only list error conditions without
> stating which should take precedence if more of them apply so
> neither of them seems wrong, strictly speaking
I'd be for restoring the original behavior (be conservative + looks like as not intended).
Any comment from netdev maintainers?
Kind regards,
Petr
> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> index 1a0c961f4ffe..509292bdf7ed 100644
> --- a/net/unix/af_unix.c
> +++ b/net/unix/af_unix.c
> @@ -992,7 +992,7 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
> struct unix_sock *u = unix_sk(sk);
> struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;
> char *sun_path = sunaddr->sun_path;
> - int err;
> + int err, mknod_err;
> unsigned int hash;
> struct unix_address *addr;
> struct hlist_head *list;
> @@ -1016,12 +1016,10 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
> if (sun_path[0]) {
> umode_t mode = S_IFSOCK |
> (SOCK_INODE(sock)->i_mode & ~current_umask());
> - err = unix_mknod(sun_path, mode, &path);
> - if (err) {
> - if (err == -EEXIST)
> - err = -EADDRINUSE;
> - goto out;
> - }
> + mknod_err = unix_mknod(sun_path, mode, &path);
> + /* do not exit on error until after u->addr check */
> + if (mknod_err == -EEXIST)
> + mknod_err = -EADDRINUSE;
> }
> err = mutex_lock_interruptible(&u->bindlock);
> @@ -1031,6 +1029,10 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
> err = -EINVAL;
> if (u->addr)
> goto out_up;
> + if (mknod_err) {
> + err = mknod_err;
> + goto out_up;
> + }
> err = -ENOMEM;
> addr = kmalloc(sizeof(*addr)+addr_len, GFP_KERNEL);
next prev parent reply other threads:[~2018-08-31 11:14 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-30 7:34 RFC: changed error code when binding unix socket twice Michal Kubecek
2018-08-31 11:14 ` Petr Vorel [this message]
2018-10-29 13:03 ` Arnd Bergmann
2018-10-29 16:33 ` Petr Vorel
2018-10-29 20:48 ` Arnd Bergmann
2018-11-07 15:56 ` Petr Vorel
2018-11-29 12:36 ` gregkh
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180831111436.GA23780@dell5510 \
--to=pvorel@suse.cz \
--cc=chrubis@suse.cz \
--cc=davem@davemloft.net \
--cc=junchi.chen@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=ltp@lists.linux.it \
--cc=mkubecek@suse.cz \
--cc=netdev@vger.kernel.org \
--cc=rweikusat@mobileactivedefense.com \
--cc=xiyou.wangcong@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).