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-rw-r--r--security/Kconfig.hardening57
1 files changed, 57 insertions, 0 deletions
diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening
index 19881341f1c2..a96d4a43ca65 100644
--- 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
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