[linux-2.6-block.git] / scripts / gcc-plugins / Kconfig

preferred-plugin-hostcc := $(if-success,[ $(gcc-version) -ge 40800 ],$(HOSTCXX),$(HOSTCC))

config PLUGIN_HOSTCC
	string
	default "$(shell,$(srctree)/scripts/gcc-plugin.sh "$(preferred-plugin-hostcc)" "$(HOSTCXX)" "$(CC)")" if CC_IS_GCC
	help
	  Host compiler used to build GCC plugins.  This can be $(HOSTCXX),
	  $(HOSTCC), or a null string if GCC plugin is unsupported.

config HAVE_GCC_PLUGINS
	bool
	help
	  An arch should select this symbol if it supports building with
	  GCC plugins.

menuconfig GCC_PLUGINS
	bool "GCC plugins"
	depends on HAVE_GCC_PLUGINS
	depends on PLUGIN_HOSTCC != ""
	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

config GCC_PLUGIN_CYC_COMPLEXITY
	bool "Compute the cyclomatic complexity of a function" if EXPERT
	depends on !COMPILE_TEST	# too noisy
	help
	  The complexity M of a function's control flow graph is defined as:
	   M = E - N + 2P
	  where

	  E = the number of edges
	  N = the number of nodes
	  P = the number of connected components (exit nodes).

	  Enabling this plugin reports the complexity to stderr during the
	  build. It mainly serves as a simple example of how to create a
	  gcc plugin for the kernel.

config GCC_PLUGIN_SANCOV
	bool
	help
	  This plugin inserts a __sanitizer_cov_trace_pc() call at the start of
	  basic blocks. It supports all gcc versions with plugin support (from
	  gcc-4.5 on). It is based on the commit "Add fuzzing coverage support"
	  by Dmitry Vyukov <dvyukov@google.com>.

config GCC_PLUGIN_LATENT_ENTROPY
	bool "Generate some entropy during boot and runtime"
	help
	  By saying Y here the kernel will instrument some kernel code to
	  extract some entropy from both original and artificially created
	  program state.  This will help especially embedded systems where
	  there is little 'natural' source of entropy normally.  The cost
	  is some slowdown of the boot process (about 0.5%) and fork and
	  irq processing.

	  Note that entropy extracted this way is not cryptographically
	  secure!

	  This plugin was ported from grsecurity/PaX. More information at:
	   * https://grsecurity.net/
	   * https://pax.grsecurity.net/

config GCC_PLUGIN_STRUCTLEAK
	bool "Force initialization of variables containing userspace addresses"
	# Currently STRUCTLEAK inserts initialization out of live scope of
	# variables from KASAN point of view. This leads to KASAN false
	# positive reports. Prohibit this combination for now.
	depends on !KASAN_EXTRA
	help
	  This plugin zero-initializes any structures containing a
	  __user attribute. This can prevent some classes of information
	  exposures.

	  This plugin was ported from grsecurity/PaX. More information at:
	   * https://grsecurity.net/
	   * https://pax.grsecurity.net/

config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL
	bool "Force initialize all struct type variables passed by reference"
	depends on GCC_PLUGIN_STRUCTLEAK
	depends on !COMPILE_TEST
	help
	  Zero initialize any struct type local variable that may be passed by
	  reference without having been initialized.

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
	help
	  If you say Y here, the layouts of structures that are entirely
	  function pointers (and have not been manually annotated with
	  __no_randomize_layout), or structures that have been explicitly
	  marked with __randomize_layout, will be randomized at compile-time.
	  This can introduce the requirement of an additional information
	  exposure vulnerability for exploits targeting these structure
	  types.

	  Enabling this feature will introduce some performance impact,
	  slightly increase memory usage, and prevent the use of forensic
	  tools like Volatility against the system (unless the kernel
	  source tree isn't cleaned after kernel installation).

	  The seed used for compilation is located at
	  scripts/gcc-plgins/randomize_layout_seed.h.  It remains after
	  a make clean to allow for external modules to be compiled with
	  the existing seed and will be removed by a make mrproper or
	  make distclean.

	  Note that the implementation requires gcc 4.7 or newer.

	  This plugin was ported from grsecurity/PaX. More information at:
	   * https://grsecurity.net/
	   * https://pax.grsecurity.net/

config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE
	bool "Use cacheline-aware structure randomization"
	depends on GCC_PLUGIN_RANDSTRUCT
	depends on !COMPILE_TEST	# do not reduce test coverage
	help
	  If you say Y here, the RANDSTRUCT randomization will make a
	  best effort at restricting randomization to cacheline-sized
	  groups of elements.  It will further not randomize bitfields
	  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
Commit	Line	Data
45332b1b MY	1	preferred-plugin-hostcc := $(if-success,[ $(gcc-version) -ge 40800 ],$(HOSTCXX),$(HOSTCC))
	2
	3	config PLUGIN_HOSTCC
	4	string
b0441333	5	default "$(shell,$(srctree)/scripts/gcc-plugin.sh "$(preferred-plugin-hostcc)" "$(HOSTCXX)" "$(CC)")" if CC_IS_GCC
45332b1b MY	6	help
	7	Host compiler used to build GCC plugins. This can be $(HOSTCXX),
	8	$(HOSTCC), or a null string if GCC plugin is unsupported.
	9
	10	config HAVE_GCC_PLUGINS
	11	bool
	12	help
	13	An arch should select this symbol if it supports building with
	14	GCC plugins.
	15
	16	menuconfig GCC_PLUGINS
	17	bool "GCC plugins"
	18	depends on HAVE_GCC_PLUGINS
	19	depends on PLUGIN_HOSTCC != ""
	20	help
	21	GCC plugins are loadable modules that provide extra features to the
	22	compiler. They are useful for runtime instrumentation and static analysis.
	23
	24	See Documentation/gcc-plugins.txt for details.
	25
	26	if GCC_PLUGINS
	27
	28	config GCC_PLUGIN_CYC_COMPLEXITY
	29	bool "Compute the cyclomatic complexity of a function" if EXPERT
	30	depends on !COMPILE_TEST # too noisy
	31	help
	32	The complexity M of a function's control flow graph is defined as:
	33	M = E - N + 2P
	34	where
	35
	36	E = the number of edges
	37	N = the number of nodes
	38	P = the number of connected components (exit nodes).
	39
	40	Enabling this plugin reports the complexity to stderr during the
	41	build. It mainly serves as a simple example of how to create a
	42	gcc plugin for the kernel.
	43
	44	config GCC_PLUGIN_SANCOV
	45	bool
	46	help
	47	This plugin inserts a __sanitizer_cov_trace_pc() call at the start of
	48	basic blocks. It supports all gcc versions with plugin support (from
	49	gcc-4.5 on). It is based on the commit "Add fuzzing coverage support"
	50	by Dmitry Vyukov <dvyukov@google.com>.
	51
	52	config GCC_PLUGIN_LATENT_ENTROPY
	53	bool "Generate some entropy during boot and runtime"
	54	help
	55	By saying Y here the kernel will instrument some kernel code to
	56	extract some entropy from both original and artificially created
	57	program state. This will help especially embedded systems where
	58	there is little 'natural' source of entropy normally. The cost
	59	is some slowdown of the boot process (about 0.5%) and fork and
	60	irq processing.
	61
	62	Note that entropy extracted this way is not cryptographically
	63	secure!
	64
	65	This plugin was ported from grsecurity/PaX. More information at:
	66	* https://grsecurity.net/
	67	* https://pax.grsecurity.net/
	68
	69	config GCC_PLUGIN_STRUCTLEAK
70	bool "Force initialization of variables containing userspace addresses"
71	# Currently STRUCTLEAK inserts initialization out of live scope of
72	# variables from KASAN point of view. This leads to KASAN false
73	# positive reports. Prohibit this combination for now.
74	depends on !KASAN_EXTRA
75	help
76	This plugin zero-initializes any structures containing a
77	__user attribute. This can prevent some classes of information
78	exposures.
79
80	This plugin was ported from grsecurity/PaX. More information at:
81	* https://grsecurity.net/
82	* https://pax.grsecurity.net/
83
84	config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL
85	bool "Force initialize all struct type variables passed by reference"
86	depends on GCC_PLUGIN_STRUCTLEAK
87	depends on !COMPILE_TEST
88	help
89	Zero initialize any struct type local variable that may be passed by
90	reference without having been initialized.
91
92	config GCC_PLUGIN_STRUCTLEAK_VERBOSE
93	bool "Report forcefully initialized variables"
94	depends on GCC_PLUGIN_STRUCTLEAK
95	depends on !COMPILE_TEST # too noisy
96	help
97	This option will cause a warning to be printed each time the
98	structleak plugin finds a variable it thinks needs to be
99	initialized. Since not all existing initializers are detected
100	by the plugin, this can produce false positive warnings.
101
102	config GCC_PLUGIN_RANDSTRUCT
103	bool "Randomize layout of sensitive kernel structures"
104	select MODVERSIONS if MODULES
105	help
106	If you say Y here, the layouts of structures that are entirely
107	function pointers (and have not been manually annotated with
108	__no_randomize_layout), or structures that have been explicitly
109	marked with __randomize_layout, will be randomized at compile-time.
110	This can introduce the requirement of an additional information
111	exposure vulnerability for exploits targeting these structure
112	types.
113
114	Enabling this feature will introduce some performance impact,
115	slightly increase memory usage, and prevent the use of forensic
116	tools like Volatility against the system (unless the kernel
117	source tree isn't cleaned after kernel installation).
118
119	The seed used for compilation is located at
120	scripts/gcc-plgins/randomize_layout_seed.h. It remains after
121	a make clean to allow for external modules to be compiled with
122	the existing seed and will be removed by a make mrproper or
123	make distclean.
124
125	Note that the implementation requires gcc 4.7 or newer.
126
127	This plugin was ported from grsecurity/PaX. More information at:
128	* https://grsecurity.net/
129	* https://pax.grsecurity.net/
130
131	config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE
132	bool "Use cacheline-aware structure randomization"
133	depends on GCC_PLUGIN_RANDSTRUCT
134	depends on !COMPILE_TEST # do not reduce test coverage
135	help
136	If you say Y here, the RANDSTRUCT randomization will make a
137	best effort at restricting randomization to cacheline-sized
138	groups of elements. It will further not randomize bitfields
139	in structures. This reduces the performance hit of RANDSTRUCT
140	at the cost of weakened randomization.
141
afaef01c AP	142	config GCC_PLUGIN_STACKLEAK
	143	bool "Erase the kernel stack before returning from syscalls"
	144	depends on GCC_PLUGINS
	145	depends on HAVE_ARCH_STACKLEAK
	146	help
	147	This option makes the kernel erase the kernel stack before
	148	returning from system calls. That reduces the information which
	149	kernel stack leak bugs can reveal and blocks some uninitialized
	150	stack variable attacks.
	151
	152	The tradeoff is the performance impact: on a single CPU system kernel
	153	compilation sees a 1% slowdown, other systems and workloads may vary
	154	and you are advised to test this feature on your expected workload
	155	before deploying it.
	156
	157	This plugin was ported from grsecurity/PaX. More information at:
	158	* https://grsecurity.net/
	159	* https://pax.grsecurity.net/
	160
10e9ae9f AP	161	config STACKLEAK_TRACK_MIN_SIZE
	162	int "Minimum stack frame size of functions tracked by STACKLEAK"
	163	default 100
	164	range 0 4096
	165	depends on GCC_PLUGIN_STACKLEAK
	166	help
	167	The STACKLEAK gcc plugin instruments the kernel code for tracking
	168	the lowest border of the kernel stack (and for some other purposes).
	169	It inserts the stackleak_track_stack() call for the functions with
	170	a stack frame size greater than or equal to this parameter.
	171	If unsure, leave the default value 100.
	172
c8d12627 AP	173	config STACKLEAK_METRICS
	174	bool "Show STACKLEAK metrics in the /proc file system"
	175	depends on GCC_PLUGIN_STACKLEAK
	176	depends on PROC_FS
	177	help
	178	If this is set, STACKLEAK metrics for every task are available in
	179	the /proc file system. In particular, /proc/<pid>/stack_depth
	180	shows the maximum kernel stack consumption for the current and
	181	previous syscalls. Although this information is not precise, it
	182	can be useful for estimating the STACKLEAK performance impact for
	183	your workloads.
	184
964c9dff AP	185	config STACKLEAK_RUNTIME_DISABLE
	186	bool "Allow runtime disabling of kernel stack erasing"
	187	depends on GCC_PLUGIN_STACKLEAK
	188	help
	189	This option provides 'stack_erasing' sysctl, which can be used in
	190	runtime to control kernel stack erasing for kernels built with
	191	CONFIG_GCC_PLUGIN_STACKLEAK.
	192
189af465 AB	193	config GCC_PLUGIN_ARM_SSP_PER_TASK
	194	bool
	195	depends on GCC_PLUGINS && ARM
	196
45332b1b	197	endif