Security/SELinux: seperate lsm specific mmap_min_addr

Currently SELinux enforcement of controls on the ability to map low memory
is determined by the mmap_min_addr tunable.  This patch causes SELinux to
ignore the tunable and instead use a seperate Kconfig option specific to how
much space the LSM should protect.

The tunable will now only control the need for CAP_SYS_RAWIO and SELinux
permissions will always protect the amount of low memory designated by
CONFIG_LSM_MMAP_MIN_ADDR.

This allows users who need to disable the mmap_min_addr controls (usual reason
being they run WINE as a non-root user) to do so and still have SELinux
controls preventing confined domains (like a web server) from being able to
map some area of low memory.

Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/mm/Kconfig b/mm/Kconfig
index c948d4ca8bde..fe5f674d7a7d 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -225,9 +225,9 @@ config DEFAULT_MMAP_MIN_ADDR
           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.
+          Programs which use vm86 functionality or have some need to map
+          this low address space will need CAP_SYS_RAWIO or disable this
+          protection by setting the value to 0.
 
           This value can be changed after boot using the
           /proc/sys/vm/mmap_min_addr tunable.