security: Create "kernel hardening" config area

Right now kernel hardening options are scattered around various Kconfig files. This can be a central place to collect these kinds of options going forward. This is initially populated with the memory initialization options from the gcc-plugins.

Kees Cook committed 7 years ago

Commit 9f671e51 parent 8c2ffd93 files · +101 −69Browse files

Unified · Split

3 files

scripts/gcc-plugins/Kconfig +6 −69
security/Kconfig +2 −0
security/Kconfig.hardening +93 −0

scripts/gcc-plugins/Kconfig+6−69

@@ -13,17 +13,19 @@ config HAVE_GCC_PLUGINS · 12 unmodified lines
13	13	An arch should select this symbol if it supports building with
14	14	GCC plugins.
15	15
16		−menuconfig GCC_PLUGINS
17		− bool "GCC plugins"
	16	+config GCC_PLUGINS
	17	+ bool
18	18	depends on HAVE_GCC_PLUGINS
19	19	depends on PLUGIN_HOSTCC != ""
	20	+ default y
20	21	help
21	22	GCC plugins are loadable modules that provide extra features to the
22	23	compiler. They are useful for runtime instrumentation and static analysis.
23	24
24	25	See Documentation/gcc-plugins.txt for details.
25	26
26		−if GCC_PLUGINS
	27	+menu "GCC plugins"
	28	+ depends on GCC_PLUGINS
27	29
28	30	config GCC_PLUGIN_CYC_COMPLEXITY
29	31	bool "Compute the cyclomatic complexity of a function" if EXPERT
@@ -66,71 +68,6 @@ config GCC_PLUGIN_LATENT_ENTROPY · 36 unmodified lines
66	68	* https://grsecurity.net/
67	69	* https://pax.grsecurity.net/
68	70
69		−config GCC_PLUGIN_STRUCTLEAK
70		− bool "Zero initialize stack variables"
71		− help
72		− While the kernel is built with warnings enabled for any missed
73		− stack variable initializations, this warning is silenced for
74		− anything passed by reference to another function, under the
75		− occasionally misguided assumption that the function will do
76		− the initialization. As this regularly leads to exploitable
77		− flaws, this plugin is available to identify and zero-initialize
78		− such variables, depending on the chosen level of coverage.
79		−
80		− This plugin was originally ported from grsecurity/PaX. More
81		− information at:
82		− * https://grsecurity.net/
83		− * https://pax.grsecurity.net/
84		−
85		−choice
86		− prompt "Coverage"
87		− depends on GCC_PLUGIN_STRUCTLEAK
88		− default GCC_PLUGIN_STRUCTLEAK_BYREF_ALL
89		− help
90		− This chooses the level of coverage over classes of potentially
91		− uninitialized variables. The selected class will be
92		− zero-initialized before use.
93		−
94		− config GCC_PLUGIN_STRUCTLEAK_USER
95		− bool "structs marked for userspace"
96		− help
97		− Zero-initialize any structures on the stack containing
98		− a __user attribute. This can prevent some classes of
99		− uninitialized stack variable exploits and information
100		− exposures, like CVE-2013-2141:
101		− https://git.kernel.org/linus/b9e146d8eb3b9eca
102		−
103		− config GCC_PLUGIN_STRUCTLEAK_BYREF
104		− bool "structs passed by reference"
105		− help
106		− Zero-initialize any structures on the stack that may
107		− be passed by reference and had not already been
108		− explicitly initialized. This can prevent most classes
109		− of uninitialized stack variable exploits and information
110		− exposures, like CVE-2017-1000410:
111		− https://git.kernel.org/linus/06e7e776ca4d3654
112		−
113		− config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL
114		− bool "anything passed by reference"
115		− help
116		− Zero-initialize any stack variables that may be passed
117		− by reference and had not already been explicitly
118		− initialized. This is intended to eliminate all classes
119		− of uninitialized stack variable exploits and information
120		− exposures.
121		−
122		−endchoice
123		−
124		−config GCC_PLUGIN_STRUCTLEAK_VERBOSE
125		− bool "Report forcefully initialized variables"
126		− depends on GCC_PLUGIN_STRUCTLEAK
127		− depends on !COMPILE_TEST # too noisy
128		− help
129		− This option will cause a warning to be printed each time the
130		− structleak plugin finds a variable it thinks needs to be
131		− initialized. Since not all existing initializers are detected
132		− by the plugin, this can produce false positive warnings.
133		−
134	71	config GCC_PLUGIN_RANDSTRUCT
135	72	bool "Randomize layout of sensitive kernel structures"
136	73	select MODVERSIONS if MODULES
@@ -226,4 +163,4 @@ config GCC_PLUGIN_ARM_SSP_PER_TASK · 89 unmodified lines
226	163	bool
227	164	depends on GCC_PLUGINS && ARM
228	165
229		−endif
	166	+endmenu

security/Kconfig+2−0

@@ -249,5 +249,7 @@ config LSM · 248 unmodified lines
249	249
250	250	If unsure, leave this as the default.
251	251
	252	+source "security/Kconfig.hardening"
	253	+
252	254	endmenu
253	255

security/Kconfig.hardening+93−0

@@ -0,0 +1,93 @@
	1	+menu "Kernel hardening options"
	2	+
	3	+config GCC_PLUGIN_STRUCTLEAK
	4	+ bool
	5	+ help
	6	+ While the kernel is built with warnings enabled for any missed
	7	+ stack variable initializations, this warning is silenced for
	8	+ anything passed by reference to another function, under the
	9	+ occasionally misguided assumption that the function will do
	10	+ the initialization. As this regularly leads to exploitable
	11	+ flaws, this plugin is available to identify and zero-initialize
	12	+ such variables, depending on the chosen level of coverage.
	13	+
	14	+ This plugin was originally ported from grsecurity/PaX. More
	15	+ information at:
	16	+ * https://grsecurity.net/
	17	+ * https://pax.grsecurity.net/
	18	+
	19	+menu "Memory initialization"
	20	+
	21	+choice
	22	+ prompt "Initialize kernel stack variables at function entry"
	23	+ default GCC_PLUGIN_STRUCTLEAK_BYREF_ALL if COMPILE_TEST && GCC_PLUGINS
	24	+ default INIT_STACK_NONE
	25	+ help
	26	+ This option enables initialization of stack variables at
	27	+ function entry time. This has the possibility to have the
	28	+ greatest coverage (since all functions can have their
	29	+ variables initialized), but the performance impact depends
	30	+ on the function calling complexity of a given workload's
	31	+ syscalls.
	32	+
	33	+ This chooses the level of coverage over classes of potentially
	34	+ uninitialized variables. The selected class will be
	35	+ initialized before use in a function.
	36	+
	37	+ config INIT_STACK_NONE
	38	+ bool "no automatic initialization (weakest)"
	39	+ help
	40	+ Disable automatic stack variable initialization.
	41	+ This leaves the kernel vulnerable to the standard
	42	+ classes of uninitialized stack variable exploits
	43	+ and information exposures.
	44	+
	45	+ config GCC_PLUGIN_STRUCTLEAK_USER
	46	+ bool "zero-init structs marked for userspace (weak)"
	47	+ depends on GCC_PLUGINS
	48	+ select GCC_PLUGIN_STRUCTLEAK
	49	+ help
	50	+ Zero-initialize any structures on the stack containing
	51	+ a __user attribute. This can prevent some classes of
	52	+ uninitialized stack variable exploits and information
	53	+ exposures, like CVE-2013-2141:
	54	+ https://git.kernel.org/linus/b9e146d8eb3b9eca
	55	+
	56	+ config GCC_PLUGIN_STRUCTLEAK_BYREF
	57	+ bool "zero-init structs passed by reference (strong)"
	58	+ depends on GCC_PLUGINS
	59	+ select GCC_PLUGIN_STRUCTLEAK
	60	+ help
	61	+ Zero-initialize any structures on the stack that may
	62	+ be passed by reference and had not already been
	63	+ explicitly initialized. This can prevent most classes
	64	+ of uninitialized stack variable exploits and information
	65	+ exposures, like CVE-2017-1000410:
	66	+ https://git.kernel.org/linus/06e7e776ca4d3654
	67	+
	68	+ config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL
	69	+ bool "zero-init anything passed by reference (very strong)"
	70	+ depends on GCC_PLUGINS
	71	+ select GCC_PLUGIN_STRUCTLEAK
	72	+ help
	73	+ Zero-initialize any stack variables that may be passed
	74	+ by reference and had not already been explicitly
	75	+ initialized. This is intended to eliminate all classes
	76	+ of uninitialized stack variable exploits and information
	77	+ exposures.
	78	+
	79	+endchoice
	80	+
	81	+config GCC_PLUGIN_STRUCTLEAK_VERBOSE
	82	+ bool "Report forcefully initialized variables"
	83	+ depends on GCC_PLUGIN_STRUCTLEAK
	84	+ depends on !COMPILE_TEST # too noisy
	85	+ help
	86	+ This option will cause a warning to be printed each time the
	87	+ structleak plugin finds a variable it thinks needs to be
	88	+ initialized. Since not all existing initializers are detected
	89	+ by the plugin, this can produce false positive warnings.
	90	+
	91	+endmenu
	92	+
	93	+endmenu