[PATCH] Add the Kconfig option for the stackprotector feature

This patch adds the config options for -fstack-protector.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andi Kleen <ak@suse.de>
CC: Andi Kleen <ak@suse.de>

diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index 927b392..0c61d00 100644 (file)
--- a/arch/x86_64/Kconfig
+++ b/arch/x86_64/Kconfig
@@ -533,6 +533,30 @@ config SECCOMP
 
          If unsure, say Y. Only embedded should say N here.
 
+config CC_STACKPROTECTOR
+       bool "Enable -fstack-protector buffer overflow detection (EXPRIMENTAL)"
+       depends on EXPERIMENTAL
+       help
+         This option turns on the -fstack-protector GCC feature. This
+         feature puts, at the beginning of critical functions, a canary
+         value on the stack just before the return address, and validates
+         the value just before actually returning.  Stack based buffer
+         overflows (that need to overwrite this return address) now also
+         overwrite the canary, which gets detected and the attack is then
+         neutralized via a kernel panic.
+
+         This feature requires gcc version 4.2 or above, or a distribution
+         gcc with the feature backported. Older versions are automatically
+         detected and for those versions, this configuration option is ignored.
+
+config CC_STACKPROTECTOR_ALL
+       bool "Use stack-protector for all functions"
+       depends on CC_STACKPROTECTOR
+       help
+         Normally, GCC only inserts the canary value protection for
+         functions that use large-ish on-stack buffers. By enabling
+         this option, GCC will be asked to do this for ALL functions.
+
 source kernel/Kconfig.hz
 
 config REORDER