]> git.baikalelectronics.ru Git - kernel.git/commit
Restrict unprivileged access to kernel syslog
authorDan Rosenberg <drosenberg@vsecurity.com>
Thu, 11 Nov 2010 22:05:18 +0000 (14:05 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 12 Nov 2010 15:55:32 +0000 (07:55 -0800)
commitfca82c35ad47294a6609b525e1c25919ad69099c
tree83bc8667309050b3538630707513574c14c51f37
parent7a527653fd40f068db61361ffe5b474b0193f75b
Restrict unprivileged access to kernel syslog

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.

[akpm@linux-foundation.org: explain the config option in kernel.txt]
Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Eugene Teo <eugeneteo@kernel.org>
Acked-by: Kees Cook <kees.cook@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Documentation/sysctl/kernel.txt
include/linux/kernel.h
kernel/printk.c
kernel/sysctl.c
security/Kconfig
security/commoncap.c