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SubjectRe: [PATCH] Restrict unprivileged access to kernel syslog
On Mon, Nov 08, 2010 at 10:28:58PM -0500, Dan Rosenberg wrote:
> The kernel syslog contains debugging information that is often useful
> during exploitation of other vulnerabilities, such as kernel heap
> addresses. Rather than futilely attempt to sanitize hundreds (or
> thousands) of printk statements and simultaneously cripple useful
> debugging functionality, it is far simpler to create an option that
> prevents unprivileged users from reading the syslog.
>
> This patch, loosely based on grsecurity's GRKERNSEC_DMESG, creates the
> dmesg_restrict sysctl. When set to "0", the default, no restrictions
> are enforced. When set to "1", only users with CAP_SYS_ADMIN can read
> the kernel syslog via dmesg(8) or other mechanisms.
>
> Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>

Acked-by: Kees Cook <kees.cook@canonical.com>

This looks good to me -- it leaves the /proc file access alone for
priv-dropping ksyslogd implementations.

-Kees

--
Kees Cook
Ubuntu Security Team


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