security: use mmap_min_addr indepedently of security models

This patch removes the dependency of mmap_min_addr on CONFIG_SECURITY.
It also sets a default mmap_min_addr of 4096.

mmapping of addresses below 4096 will only be possible for processes
with CAP_SYS_RAWIO.

Signed-off-by: Christoph Lameter <[email protected]>
Acked-by: Eric Paris <[email protected]>
Looks-ok-by: Linus Torvalds <[email protected]>
Signed-off-by: James Morris <[email protected]>
This commit is contained in:
Christoph Lameter 2009-06-03 16:04:31 -04:00 • committed by James Morris
commit e0a94c2a63
7 changed files with 25 additions and 28 deletions

View file

@ -110,29 +110,9 @@ config SECURITY_ROOTPLUG
See <http://www.linuxjournal.com/article.php?sid=6279> for
more information about this module.
If you are unsure how to answer this question, answer N.
config SECURITY_DEFAULT_MMAP_MIN_ADDR
int "Low address space to protect from user allocation"
depends on SECURITY
default 0
help
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 ia64, ppc64 and x86 users with lots of address space
a value of 65536 is reasonable and should cause no problems.
On arm and other archs it should not be higher than 32768.
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.
source security/selinux/Kconfig
source security/smack/Kconfig
source security/tomoyo/Kconfig