security: Move stackleak config to Kconfig.hardening

This moves the stackleak plugin options to Kconfig.hardening's memory
initialization menu.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Alexander Popov <alex.popov@linux.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>

diff --git a/scripts/gcc-plugins/Kconfig b/scripts/gcc-plugins/Kconfig
index 352f038..80220ed 100644 (file)
--- a/scripts/gcc-plugins/Kconfig
+++ b/scripts/gcc-plugins/Kconfig
@@ -108,57 +108,6 @@ config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE
          in structures.  This reduces the performance hit of RANDSTRUCT
          at the cost of weakened randomization.
 
-config GCC_PLUGIN_STACKLEAK
-       bool "Erase the kernel stack before returning from syscalls"
-       depends on GCC_PLUGINS
-       depends on HAVE_ARCH_STACKLEAK
-       help
-         This option makes the kernel erase the kernel stack before
-         returning from system calls. That reduces the information which
-         kernel stack leak bugs can reveal and blocks some uninitialized
-         stack variable attacks.
-
-         The tradeoff is the performance impact: on a single CPU system kernel
-         compilation sees a 1% slowdown, other systems and workloads may vary
-         and you are advised to test this feature on your expected workload
-         before deploying it.
-
-         This plugin was ported from grsecurity/PaX. More information at:
-          * https://grsecurity.net/
-          * https://pax.grsecurity.net/
-
-config STACKLEAK_TRACK_MIN_SIZE
-       int "Minimum stack frame size of functions tracked by STACKLEAK"
-       default 100
-       range 0 4096
-       depends on GCC_PLUGIN_STACKLEAK
-       help
-         The STACKLEAK gcc plugin instruments the kernel code for tracking
-         the lowest border of the kernel stack (and for some other purposes).
-         It inserts the stackleak_track_stack() call for the functions with
-         a stack frame size greater than or equal to this parameter.
-         If unsure, leave the default value 100.
-
-config STACKLEAK_METRICS
-       bool "Show STACKLEAK metrics in the /proc file system"
-       depends on GCC_PLUGIN_STACKLEAK
-       depends on PROC_FS
-       help
-         If this is set, STACKLEAK metrics for every task are available in
-         the /proc file system. In particular, /proc/<pid>/stack_depth
-         shows the maximum kernel stack consumption for the current and
-         previous syscalls. Although this information is not precise, it
-         can be useful for estimating the STACKLEAK performance impact for
-         your workloads.
-
-config STACKLEAK_RUNTIME_DISABLE
-       bool "Allow runtime disabling of kernel stack erasing"
-       depends on GCC_PLUGIN_STACKLEAK
-       help
-         This option provides 'stack_erasing' sysctl, which can be used in
-         runtime to control kernel stack erasing for kernels built with
-         CONFIG_GCC_PLUGIN_STACKLEAK.
-
 config GCC_PLUGIN_ARM_SSP_PER_TASK
        bool
        depends on GCC_PLUGINS && ARM

diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening
index 1988134..a96d4a4 100644 (file)
--- a/security/Kconfig.hardening
+++ b/security/Kconfig.hardening
@@ -88,6 +88,63 @@ config GCC_PLUGIN_STRUCTLEAK_VERBOSE
          initialized. Since not all existing initializers are detected
          by the plugin, this can produce false positive warnings.
 
+config GCC_PLUGIN_STACKLEAK
+       bool "Poison kernel stack before returning from syscalls"
+       depends on GCC_PLUGINS
+       depends on HAVE_ARCH_STACKLEAK
+       help
+         This option makes the kernel erase the kernel stack before
+         returning from system calls. This has the effect of leaving
+         the stack initialized to the poison value, which both reduces
+         the lifetime of any sensitive stack contents and reduces
+         potential for uninitialized stack variable exploits or information
+         exposures (it does not cover functions reaching the same stack
+         depth as prior functions during the same syscall). This blocks
+         most uninitialized stack variable attacks, with the performance
+         impact being driven by the depth of the stack usage, rather than
+         the function calling complexity.
+
+         The performance impact on a single CPU system kernel compilation
+         sees a 1% slowdown, other systems and workloads may vary and you
+         are advised to test this feature on your expected workload before
+         deploying it.
+
+         This plugin was ported from grsecurity/PaX. More information at:
+          * https://grsecurity.net/
+          * https://pax.grsecurity.net/
+
+config STACKLEAK_TRACK_MIN_SIZE
+       int "Minimum stack frame size of functions tracked by STACKLEAK"
+       default 100
+       range 0 4096
+       depends on GCC_PLUGIN_STACKLEAK
+       help
+         The STACKLEAK gcc plugin instruments the kernel code for tracking
+         the lowest border of the kernel stack (and for some other purposes).
+         It inserts the stackleak_track_stack() call for the functions with
+         a stack frame size greater than or equal to this parameter.
+         If unsure, leave the default value 100.
+
+config STACKLEAK_METRICS
+       bool "Show STACKLEAK metrics in the /proc file system"
+       depends on GCC_PLUGIN_STACKLEAK
+       depends on PROC_FS
+       help
+         If this is set, STACKLEAK metrics for every task are available in
+         the /proc file system. In particular, /proc/<pid>/stack_depth
+         shows the maximum kernel stack consumption for the current and
+         previous syscalls. Although this information is not precise, it
+         can be useful for estimating the STACKLEAK performance impact for
+         your workloads.
+
+config STACKLEAK_RUNTIME_DISABLE
+       bool "Allow runtime disabling of kernel stack erasing"
+       depends on GCC_PLUGIN_STACKLEAK
+       help
+         This option provides 'stack_erasing' sysctl, which can be used in
+         runtime to control kernel stack erasing for kernels built with
+         CONFIG_GCC_PLUGIN_STACKLEAK.
+
 endmenu
 
 endmenu