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| author | Christoph Lameter <cl@linux-foundation.org> | 2009-06-03 16:04:31 -0400 |
|---|---|---|
| committer | James Morris <jmorris@namei.org> | 2009-06-04 12:07:48 +1000 |
| commit | e0a94c2a63f2644826069044649669b5e7ca75d3 (patch) | |
| tree | debf8a9af6ac23dadd116dc1cd1f9dcefe9629c6 /mm/Kconfig | |
| parent | 7d2948b1248109dbc7f4aaf9867c54b1912d494c (diff) | |
| download | lwn-e0a94c2a63f2644826069044649669b5e7ca75d3.tar.gz lwn-e0a94c2a63f2644826069044649669b5e7ca75d3.zip | |
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>
Diffstat (limited to 'mm/Kconfig')
| -rw-r--r-- | mm/Kconfig | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/mm/Kconfig b/mm/Kconfig index c2b57d81e153..71830ba7b986 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -226,6 +226,25 @@ config HAVE_MLOCKED_PAGE_BIT 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 |