diff options
| -rw-r--r-- | Makefile | 5 | ||||
| -rw-r--r-- | scripts/gcc-plugins/Kconfig | 126 | ||||
| -rw-r--r-- | security/Kconfig | 2 | ||||
| -rw-r--r-- | security/Kconfig.hardening | 164 |
4 files changed, 177 insertions, 120 deletions
@@ -748,6 +748,11 @@ KBUILD_CFLAGS += -fomit-frame-pointer endif endif +# Initialize all stack variables with a pattern, if desired. +ifdef CONFIG_INIT_STACK_ALL +KBUILD_CFLAGS += -ftrivial-auto-var-init=pattern +endif + DEBUG_CFLAGS := $(call cc-option, -fno-var-tracking-assignments) ifdef CONFIG_DEBUG_INFO diff --git a/scripts/gcc-plugins/Kconfig b/scripts/gcc-plugins/Kconfig index 74271dba4f94..80220ed26a35 100644 --- a/scripts/gcc-plugins/Kconfig +++ b/scripts/gcc-plugins/Kconfig @@ -13,17 +13,19 @@ config HAVE_GCC_PLUGINS An arch should select this symbol if it supports building with GCC plugins. -menuconfig GCC_PLUGINS - bool "GCC plugins" +config GCC_PLUGINS + bool depends on HAVE_GCC_PLUGINS depends on PLUGIN_HOSTCC != "" + default y help GCC plugins are loadable modules that provide extra features to the compiler. They are useful for runtime instrumentation and static analysis. See Documentation/gcc-plugins.txt for details. -if GCC_PLUGINS +menu "GCC plugins" + depends on GCC_PLUGINS config GCC_PLUGIN_CYC_COMPLEXITY bool "Compute the cyclomatic complexity of a function" if EXPERT @@ -66,71 +68,6 @@ config GCC_PLUGIN_LATENT_ENTROPY * https://grsecurity.net/ * https://pax.grsecurity.net/ -config GCC_PLUGIN_STRUCTLEAK - bool "Zero initialize stack variables" - help - While the kernel is built with warnings enabled for any missed - stack variable initializations, this warning is silenced for - anything passed by reference to another function, under the - occasionally misguided assumption that the function will do - the initialization. As this regularly leads to exploitable - flaws, this plugin is available to identify and zero-initialize - such variables, depending on the chosen level of coverage. - - This plugin was originally ported from grsecurity/PaX. More - information at: - * https://grsecurity.net/ - * https://pax.grsecurity.net/ - -choice - prompt "Coverage" - depends on GCC_PLUGIN_STRUCTLEAK - default GCC_PLUGIN_STRUCTLEAK_BYREF_ALL - help - This chooses the level of coverage over classes of potentially - uninitialized variables. The selected class will be - zero-initialized before use. - - config GCC_PLUGIN_STRUCTLEAK_USER - bool "structs marked for userspace" - help - Zero-initialize any structures on the stack containing - a __user attribute. This can prevent some classes of - uninitialized stack variable exploits and information - exposures, like CVE-2013-2141: - https://git.kernel.org/linus/b9e146d8eb3b9eca - - config GCC_PLUGIN_STRUCTLEAK_BYREF - bool "structs passed by reference" - help - Zero-initialize any structures on the stack that may - be passed by reference and had not already been - explicitly initialized. This can prevent most classes - of uninitialized stack variable exploits and information - exposures, like CVE-2017-1000410: - https://git.kernel.org/linus/06e7e776ca4d3654 - - config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL - bool "anything passed by reference" - help - Zero-initialize any stack variables that may be passed - by reference and had not already been explicitly - initialized. This is intended to eliminate all classes - of uninitialized stack variable exploits and information - exposures. - -endchoice - -config GCC_PLUGIN_STRUCTLEAK_VERBOSE - bool "Report forcefully initialized variables" - depends on GCC_PLUGIN_STRUCTLEAK - depends on !COMPILE_TEST # too noisy - help - This option will cause a warning to be printed each time the - structleak plugin finds a variable it thinks needs to be - initialized. Since not all existing initializers are detected - by the plugin, this can produce false positive warnings. - config GCC_PLUGIN_RANDSTRUCT bool "Randomize layout of sensitive kernel structures" select MODVERSIONS if MODULES @@ -171,59 +108,8 @@ 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 -endif +endmenu diff --git a/security/Kconfig b/security/Kconfig index 353cfef71d4e..aeac3676dd4d 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -287,5 +287,7 @@ config LSM If unsure, leave this as the default. +source "security/Kconfig.hardening" + endmenu diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening new file mode 100644 index 000000000000..0a1d4ca314f4 --- /dev/null +++ b/security/Kconfig.hardening @@ -0,0 +1,164 @@ +menu "Kernel hardening options" + +config GCC_PLUGIN_STRUCTLEAK + bool + help + While the kernel is built with warnings enabled for any missed + stack variable initializations, this warning is silenced for + anything passed by reference to another function, under the + occasionally misguided assumption that the function will do + the initialization. As this regularly leads to exploitable + flaws, this plugin is available to identify and zero-initialize + such variables, depending on the chosen level of coverage. + + This plugin was originally ported from grsecurity/PaX. More + information at: + * https://grsecurity.net/ + * https://pax.grsecurity.net/ + +menu "Memory initialization" + +config CC_HAS_AUTO_VAR_INIT + def_bool $(cc-option,-ftrivial-auto-var-init=pattern) + +choice + prompt "Initialize kernel stack variables at function entry" + default GCC_PLUGIN_STRUCTLEAK_BYREF_ALL if COMPILE_TEST && GCC_PLUGINS + default INIT_STACK_ALL if COMPILE_TEST && CC_HAS_AUTO_VAR_INIT + default INIT_STACK_NONE + help + This option enables initialization of stack variables at + function entry time. This has the possibility to have the + greatest coverage (since all functions can have their + variables initialized), but the performance impact depends + on the function calling complexity of a given workload's + syscalls. + + This chooses the level of coverage over classes of potentially + uninitialized variables. The selected class will be + initialized before use in a function. + + config INIT_STACK_NONE + bool "no automatic initialization (weakest)" + help + Disable automatic stack variable initialization. + This leaves the kernel vulnerable to the standard + classes of uninitialized stack variable exploits + and information exposures. + + config GCC_PLUGIN_STRUCTLEAK_USER + bool "zero-init structs marked for userspace (weak)" + depends on GCC_PLUGINS + select GCC_PLUGIN_STRUCTLEAK + help + Zero-initialize any structures on the stack containing + a __user attribute. This can prevent some classes of + uninitialized stack variable exploits and information + exposures, like CVE-2013-2141: + https://git.kernel.org/linus/b9e146d8eb3b9eca + + config GCC_PLUGIN_STRUCTLEAK_BYREF + bool "zero-init structs passed by reference (strong)" + depends on GCC_PLUGINS + select GCC_PLUGIN_STRUCTLEAK + help + Zero-initialize any structures on the stack that may + be passed by reference and had not already been + explicitly initialized. This can prevent most classes + of uninitialized stack variable exploits and information + exposures, like CVE-2017-1000410: + https://git.kernel.org/linus/06e7e776ca4d3654 + + config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL + bool "zero-init anything passed by reference (very strong)" + depends on GCC_PLUGINS + select GCC_PLUGIN_STRUCTLEAK + help + Zero-initialize any stack variables that may be passed + by reference and had not already been explicitly + initialized. This is intended to eliminate all classes + of uninitialized stack variable exploits and information + exposures. + + config INIT_STACK_ALL + bool "0xAA-init everything on the stack (strongest)" + depends on CC_HAS_AUTO_VAR_INIT + help + Initializes everything on the stack with a 0xAA + pattern. This is intended to eliminate all classes + of uninitialized stack variable exploits and information + exposures, even variables that were warned to have been + left uninitialized. + +endchoice + +config GCC_PLUGIN_STRUCTLEAK_VERBOSE + bool "Report forcefully initialized variables" + depends on GCC_PLUGIN_STRUCTLEAK + depends on !COMPILE_TEST # too noisy + help + This option will cause a warning to be printed each time the + structleak plugin finds a variable it thinks needs to be + 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 |