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>
diff --git a/include/linux/mm.h b/include/linux/mm.h
index bff1f0d..0c21af6 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -580,12 +580,10 @@
*/
static inline unsigned long round_hint_to_min(unsigned long hint)
{
-#ifdef CONFIG_SECURITY
hint &= PAGE_MASK;
if (((void *)hint != NULL) &&
(hint < mmap_min_addr))
return PAGE_ALIGN(mmap_min_addr);
-#endif
return hint;
}
diff --git a/include/linux/security.h b/include/linux/security.h
index d5fd616..5eff459 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -2197,6 +2197,8 @@
unsigned long addr,
unsigned long addr_only)
{
+ if ((addr < mmap_min_addr) && !capable(CAP_SYS_RAWIO))
+ return -EACCES;
return 0;
}
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 149581f..45bd711 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1237,7 +1237,6 @@
.strategy = &sysctl_jiffies,
},
#endif
-#ifdef CONFIG_SECURITY
{
.ctl_name = CTL_UNNUMBERED,
.procname = "mmap_min_addr",
@@ -1246,7 +1245,6 @@
.mode = 0644,
.proc_handler = &proc_doulongvec_minmax,
},
-#endif
#ifdef CONFIG_NUMA
{
.ctl_name = CTL_UNNUMBERED,
diff --git a/mm/Kconfig b/mm/Kconfig
index c2b57d8..71830ba 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -226,6 +226,25 @@
config MMU_NOTIFIER
bool
+config DEFAULT_MMAP_MIN_ADDR
+ int "Low address space to protect from user allocation"
+ default 4096
+ 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.
+
+
config NOMMU_INITIAL_TRIM_EXCESS
int "Turn on mmap() excess space trimming before booting"
depends on !MMU
diff --git a/mm/mmap.c b/mm/mmap.c
index 6b7b1a9..2b43fa1 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -87,6 +87,9 @@
int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
struct percpu_counter vm_committed_as;
+/* amount of vm to protect from userspace access */
+unsigned long mmap_min_addr = CONFIG_DEFAULT_MMAP_MIN_ADDR;
+
/*
* Check that a process has enough memory to allocate a new virtual
* mapping. 0 means there is enough memory for the allocation to
diff --git a/security/Kconfig b/security/Kconfig
index bb24477..d23c839 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -110,29 +110,9 @@
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
diff --git a/security/security.c b/security/security.c
index 5284255..dc7674f 100644
--- a/security/security.c
+++ b/security/security.c
@@ -26,9 +26,6 @@
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 */