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Date: Tue, 26 Jul 2011 03:40:13 +0400
From: Solar Designer <solar@...nwall.com>
To: Vasiliy Kulikov <segoon@...nwall.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
NeilBrown <neilb@...e.de>, Stephen Smalley <sds@...ho.nsa.gov>,
kernel-hardening@...ts.openwall.com,
James Morris <jmorris@...ei.org>, linux-kernel@...r.kernel.org,
Greg Kroah-Hartman <gregkh@...e.de>,
Andrew Morton <akpm@...ux-foundation.org>,
"David S. Miller" <davem@...emloft.net>,
Jiri Slaby <jslaby@...e.cz>,
Alexander Viro <viro@...iv.linux.org.uk>,
linux-fsdevel@...r.kernel.org,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
Eric Paris <eparis@...hat.com>, Willy Tarreau <w@....eu>,
Sebastian Krahmer <krahmer@...e.de>
Subject: Re: [PATCH] move RLIMIT_NPROC check from set_user() to do_execve_common()
Vasiliy,
On Mon, Jul 25, 2011 at 09:14:23PM +0400, Vasiliy Kulikov wrote:
> @@ -1433,6 +1433,19 @@ static int do_execve_common(const char *filename,
> struct files_struct *displaced;
> bool clear_in_exec;
> int retval;
> + const struct cred *cred = current_cred();
> +
> + /*
> + * We move the actual failure in case of RLIMIT_NPROC excess from
> + * set*uid() to execve() because too many poorly written programs
> + * don't check setuid() return code. Here we additionally recheck
> + * whether NPROC limit is still exceeded.
> + */
> + if ((current->flags & PF_NPROC_EXCEEDED) &&
> + atomic_read(&cred->user->processes) > rlimit(RLIMIT_NPROC)) {
> + retval = -EAGAIN;
> + goto out_ret;
> + }
Do you possibly need:
current->flags &= ~PF_NPROC_EXCEEDED;
somewhere after this point?
I think it's weird to have past set_user() failure affect other than the
very next execve().
Perhaps also reset the flag on fork() because we have an RLIMIT_NPROC
check on fork() anyway.
Thanks,
Alexander
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