1menu "Kernel hardening options" 2 3config 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 19menu "Memory initialization" 20 21choice 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 79endchoice 80 81config 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 91endmenu 92 93endmenu 94