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SubjectRe: [PATCH 06/12] procfs: make /proc/*/stack 0400
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On Sun, Sep 29, 2013 at 3:37 AM, Djalal Harouni <tixxdz@opendz.org> wrote:
> On Thu, Sep 26, 2013 at 03:43:24PM -0500, Kees Cook wrote:
>> On Wed, Sep 25, 2013 at 3:14 PM, Djalal Harouni <tixxdz@opendz.org> wrote:
>> > The /proc/*/stack contains sensitive information and currently its mode
>> > is 0444. Change this to 0400 so the VFS will be able to block
>> > unprivileged processes to get file descriptors on arbitrary privileged
>> > /proc/*/stack files.
>> >
>> > The /proc/*/stack is a /procfs ONE file that shares the same ->open()
>> > file operation with other ONE files. Doing a ptrace_may_access() check
>> > during open() might break userspace from accessing other ONE files
>> > like /proc/*/stat and /proc/*/statm.
>> >
>> > Therfore make it 0400 for now, and improve its check during ->read()
>> > in the next following patch.
>> >
>> > Cc: Kees Cook <keescook@chromium.org>
>> > Cc: Eric W. Biederman <ebiederm@xmission.com>
>> > Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
>>
>> While the rest of the series is being discussed, I think it would be
>> nice to at least get this into the tree. Fixing this reduces which
>> processes are exposed to ASLR leaks. The rest of the series closes the
>> remaining holes.
> Kees I guess it's ok to add your Acked-by for this one, for v2

Yes, please. :)

Acked-by: Kees Cook <keescook@chromium.org>

-Kees

--
Kees Cook
Chrome OS Security


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