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 <cl@linux-foundation.org>
Acked-by: Eric Paris <eparis@redhat.com>
Looks-ok-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: James Morris <jmorris@namei.org>

2 files changed, 1 insertions, 24 deletions

diff --git a/security/Kconfig b/security/Kconfig
index bb244774e9d7..d23c839038f0 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -110,28 +110,8 @@ 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.
 
+          If you are unsure how to answer this question, answer N.
 
 source security/selinux/Kconfig
 source security/smack/Kconfig
diff --git a/security/security.c b/security/security.c
index 5284255c5cdf..dc7674fbfc7a 100644
--- a/security/security.c
+++ b/security/security.c
@@ -26,9 +26,6 @@ extern void security_fixup_ops(struct security_operations *ops);
 
 struct security_operations *security_ops;       /* Initialized to NULL */
 
-/* amount of vm to protect from userspace access */
-unsigned long mmap_min_addr = CONFIG_SECURITY_DEFAULT_MMAP_MIN_ADDR;
-
 static inline int verify(struct security_operations *ops)
 {
         /* verify the security_operations structure exists */