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Message-Id: <20190410161612.18545-3-keescook@chromium.org>
Date: Wed, 10 Apr 2019 09:16:11 -0700
From: Kees Cook <keescook@...omium.org>
To: Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc: Kees Cook <keescook@...omium.org>,
Alexander Potapenko <glider@...gle.com>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Kostya Serebryany <kcc@...gle.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Sandeep Patil <sspatil@...roid.com>,
Laura Abbott <labbott@...hat.com>,
Randy Dunlap <rdunlap@...radead.org>,
Alexander Popov <alpopov@...ecurity.com>,
Michal Marek <michal.lkml@...kovi.net>,
Emese Revfy <re.emese@...il.com>,
James Morris <jmorris@...ei.org>,
"Serge E. Hallyn" <serge@...lyn.com>,
linux-kbuild@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-security-module@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Subject: [PATCH 2/3] kbuild: 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@...omium.org>
---
scripts/gcc-plugins/Kconfig | 51 ---------------------------------
security/Kconfig.hardening | 57 +++++++++++++++++++++++++++++++++++++
2 files changed, 57 insertions(+), 51 deletions(-)
diff --git a/scripts/gcc-plugins/Kconfig b/scripts/gcc-plugins/Kconfig
index 01874ef0f883..50cfcf1ed979 100644
--- a/scripts/gcc-plugins/Kconfig
+++ b/scripts/gcc-plugins/Kconfig
@@ -107,57 +107,6 @@ 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 8223a8ab1a12..9942d9869864 100644
--- a/security/Kconfig.hardening
+++ b/security/Kconfig.hardening
@@ -89,6 +89,63 @@ 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
--
2.17.1
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