linux-kernel - Re: [SECURITY] /proc/$pid/ leaks contents across setuid exec

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 8 Feb 2011 11:44:40 +1100 (EST)
From:	James Morris <jmorris@...ei.org>
To:	Kees Cook <kees.cook@...onical.com>
cc:	linux-kernel@...r.kernel.org
Subject: Re: [SECURITY] /proc/$pid/ leaks contents across setuid exec

On Mon, 7 Feb 2011, Kees Cook wrote:

> $ ./procleak.py auxv,syscall /usr/bin/passwd
> running
> AT_BASE:   0x7f2828bde000
> AT_RANDOM: 0x7fff80bde7c9
> Changing password for kees.
> (current) UNIX password: 0 0x0 0x7fff80bdda90 0x1ff 0x7fff80bdd580 0x7f2828dc57c0 0x7f28287cec1d 0x7fff80bdd088 0x7f28282fe6c0
> 
> There needs to be some way to break the connection to these files across
> the setuid exec, or perform some sort of revalidation of permissions. (Maybe
> check dumpable?)

The way to do this is to set O_CLOEXEC.

See: 

http://udrepper.livejournal.com/20407.html
https://www.securecoding.cert.org/confluence/display/seccode/FIO42-C.+Ensure+files+are+properly+closed+when+they+are+no+longer+needed

Changing the behavior in the core kernel will break userspace.



- James
-- 
James Morris
<jmorris@...ei.org>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/