From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: "Zach, Yoav" <yoav.zach@intel.com>
Cc: akpm@osdl.org, torvalds@osdl.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH]: non-readable binaries - binfmt_misc 2.6.0-test4
Date: Sun, 31 Aug 2003 23:45:11 +0100 [thread overview]
Message-ID: <1062369910.12059.1.camel@dhcp23.swansea.linux.org.uk> (raw)
In-Reply-To: <2C83850C013A2540861D03054B478C0601CF64C8@hasmsx403.iil.intel.com>
On Sul, 2003-08-31 at 22:41, Zach, Yoav wrote:
> The proposed patch solves a problem for interpreters that need to
> execute a non-readable file, which cannot be read in userland. To handle
You've added a security hole.
> + if (fmt->flags & MISC_FMT_OPEN_BINARY) {
> + /* if the binary should be opened on behalf of the
> + * interpreter than keep it open and assign it a
> descriptor */
> + fd = get_unused_fd ();
> + if (fd < 0) {
At this point your file table might be shared with another thread (see
binfmt_elf in 2.4 - I dunno if 2.6 has been fixed for this exploit yet).
You need to unshare the file table before you modify it during the exec.
Otherwise it looks fairly sane.
next prev parent reply other threads:[~2003-08-31 22:47 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-08-31 21:41 Zach, Yoav
2003-08-31 22:12 ` Herbert Poetzl
2003-08-31 22:48 ` Alan Cox
2003-08-31 22:45 ` Alan Cox [this message]
2003-08-31 22:58 ` Alan Cox
2003-09-01 4:20 ` Willy Tarreau
2003-08-31 23:01 ` Linus Torvalds
2003-09-04 6:30 Zach, Yoav
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