|author||Eric Paris <email@example.com>||2008-01-31 15:11:22 -0500|
|committer||James Morris <firstname.lastname@example.org>||2008-02-06 21:39:46 +0800|
security: allow Kconfig to set default mmap_min_addr protection
Since it was decided that low memory protection from userspace couldn't be turned on by default add a Kconfig option to allow users/distros to set a default at compile time. This value is still tunable after boot in /proc/sys/vm/mmap_min_addr Discussion: http://email@example.com/msg02543.html Signed-off-by: Eric Paris <firstname.lastname@example.org> Signed-off-by: James Morris <email@example.com>
Diffstat (limited to 'security/Kconfig')
1 files changed, 18 insertions, 0 deletions
diff --git a/security/Kconfig b/security/Kconfig
index 25ffe1b9dc9..5dfc206748c 100644
@@ -104,6 +104,24 @@ config SECURITY_ROOTPLUG
If you are unsure how to answer this question, answer N.
+ int "Low address space to protect from user allocation"
+ depends on SECURITY
+ default 0
+ This is the portion of low virtual memory which should be protected
+ from userspace allocation. Keeping a user from writing to low pages
+ can help reduce the impact of kernel NULL pointer bugs.
+ For most users with lots of address space a value of 65536 is
+ reasonable and should cause no problems. Programs which use vm86
+ functionality would either need additional permissions from either
+ the LSM or the capabilities module or have this protection disabled.
+ This value can be changed after boot using the
+ /proc/sys/vm/mmap_min_addr tunable.