There are multiple architectures that support CONFIG_DEBUG_RODATA and CONFIG_SET_MODULE_RONX. These options also now have the ability to be turned off at runtime. Move these to an architecture independent location and make these options def_bool y for almost all of those arches. Signed-off-by: Laura Abbott <labbott@xxxxxxxxxx> --- v3: Make these configs selectable for arm. Include some documentation about how the setup of the optional Kconfigs work as well. Stop spelling 'kenrel' in prompt text. --- Documentation/security/self-protection.txt | 6 ++++++ arch/Kconfig | 34 ++++++++++++++++++++++++++++++ arch/arm/Kconfig | 4 ++++ arch/arm/Kconfig.debug | 11 ---------- arch/arm/mm/Kconfig | 12 ----------- arch/arm64/Kconfig | 5 ++--- arch/arm64/Kconfig.debug | 11 ---------- arch/parisc/Kconfig | 1 + arch/parisc/Kconfig.debug | 11 ---------- arch/s390/Kconfig | 5 ++--- arch/s390/Kconfig.debug | 3 --- arch/x86/Kconfig | 5 ++--- arch/x86/Kconfig.debug | 11 ---------- 13 files changed, 51 insertions(+), 68 deletions(-) diff --git a/Documentation/security/self-protection.txt b/Documentation/security/self-protection.txt index 3010576..f41dd00 100644 --- a/Documentation/security/self-protection.txt +++ b/Documentation/security/self-protection.txt @@ -56,6 +56,12 @@ CONFIG_DEBUG_SET_MODULE_RONX, which seek to make sure that code is not writable, data is not executable, and read-only data is neither writable nor executable. +Most architectures have these options on by default and not user selectable. +For some architectures like arm that wish to have these be selectable, +the architecture Kconfig can select ARCH_OPTIONAL_KERNEL_RWX to enable +a Kconfig prompt. CONFIG_ARCH_OPTIONAL_KERNEL_RWX_DEFAULT determines +the default setting when ARCH_OPTIONAL_KERNEL_RWX is enabled. + #### Function pointers and sensitive variables must not be writable Vast areas of kernel memory contain function pointers that are looked diff --git a/arch/Kconfig b/arch/Kconfig index 99839c2..3f8b8be 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -781,4 +781,38 @@ config VMAP_STACK the stack to map directly to the KASAN shadow map using a formula that is incorrect if the stack is in vmalloc space. +config ARCH_OPTIONAL_KERNEL_RWX + def_bool n + +config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT + def_bool n + +config ARCH_HAS_STRICT_KERNEL_RWX + def_bool n + +config DEBUG_RODATA + bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX + depends on ARCH_HAS_STRICT_KERNEL_RWX + default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT + help + If this is set, kernel text and rodata memory will be made read-only, + and non-text memory will be made non-executable. This provides + protection against certain security exploits (e.g. executing the heap + or modifying text) + + These features are considered standard security practice these days. + You should say Y here in almost all cases. + +config ARCH_HAS_STRICT_MODULE_RWX + def_bool n + +config DEBUG_SET_MODULE_RONX + bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX + depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES + default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT + help + If this is set, module text and rodata memory will be made read-only, + and non-text memory will be made non-executable. This provides + protection against certain security exploits (e.g. writing to text) + source "kernel/gcov/Kconfig" diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 186c4c2..8748353 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -4,10 +4,14 @@ config ARM select ARCH_CLOCKSOURCE_DATA select ARCH_HAS_DEVMEM_IS_ALLOWED select ARCH_HAS_ELF_RANDOMIZE + select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL + select ARCH_HAS_STRICT_MODULE_RWX if MMU select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST select ARCH_HAVE_CUSTOM_GPIO_H select ARCH_HAS_GCOV_PROFILE_ALL select ARCH_MIGHT_HAVE_PC_PARPORT + select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX + select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7 select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_USE_BUILTIN_BSWAP select ARCH_USE_CMPXCHG_LOCKREF diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug index d83f7c3..426d271 100644 --- a/arch/arm/Kconfig.debug +++ b/arch/arm/Kconfig.debug @@ -1738,17 +1738,6 @@ config PID_IN_CONTEXTIDR additional instructions during context switch. Say Y here only if you are planning to use hardware trace tools with this kernel. -config DEBUG_SET_MODULE_RONX - bool "Set loadable kernel module data as NX and text as RO" - depends on MODULES && MMU - ---help--- - This option helps catch unintended modifications to loadable - kernel module's text and read-only data. It also prevents execution - of module data. Such protection may interfere with run-time code - patching and dynamic kernel tracing - and they might also protect - against certain classes of kernel exploits. - If in doubt, say "N". - source "drivers/hwtracing/coresight/Kconfig" endmenu diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index f68e8ec..419a035 100644 --- a/arch/arm/mm/Kconfig +++ b/arch/arm/mm/Kconfig @@ -1051,18 +1051,6 @@ config ARCH_SUPPORTS_BIG_ENDIAN This option specifies the architecture can support big endian operation. -config DEBUG_RODATA - bool "Make kernel text and rodata read-only" - depends on MMU && !XIP_KERNEL - default y if CPU_V7 - help - If this is set, kernel text and rodata memory will be made - read-only, and non-text kernel memory will be made non-executable. - The tradeoff is that each region is padded to section-size (1MiB) - boundaries (because their permissions are different and splitting - the 1M pages into 4K ones causes TLB performance problems), which - can waste memory. - config DEBUG_ALIGN_RODATA bool "Make rodata strictly non-executable" depends on DEBUG_RODATA diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 1117421..e1efbcc 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -13,6 +13,8 @@ config ARM64 select ARCH_HAS_GIGANTIC_PAGE select ARCH_HAS_KCOV select ARCH_HAS_SG_CHAIN + select ARCH_HAS_STRICT_KERNEL_RWX + select ARCH_HAS_STRICT_MODULE_RWX select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST select ARCH_USE_CMPXCHG_LOCKREF select ARCH_SUPPORTS_ATOMIC_RMW @@ -123,9 +125,6 @@ config ARCH_PHYS_ADDR_T_64BIT config MMU def_bool y -config DEBUG_RODATA - def_bool y - config ARM64_PAGE_SHIFT int default 16 if ARM64_64K_PAGES diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug index d1ebd46..939815e 100644 --- a/arch/arm64/Kconfig.debug +++ b/arch/arm64/Kconfig.debug @@ -71,17 +71,6 @@ config DEBUG_WX If in doubt, say "Y". -config DEBUG_SET_MODULE_RONX - bool "Set loadable kernel module data as NX and text as RO" - depends on MODULES - default y - help - Is this is set, kernel module text and rodata will be made read-only. - This is to help catch accidental or malicious attempts to change the - kernel's executable code. - - If in doubt, say Y. - config DEBUG_ALIGN_RODATA depends on DEBUG_RODATA bool "Align linker sections up to SECTION_SIZE" diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig index 3a71f38..ad294b3 100644 --- a/arch/parisc/Kconfig +++ b/arch/parisc/Kconfig @@ -8,6 +8,7 @@ config PARISC select HAVE_SYSCALL_TRACEPOINTS select ARCH_WANT_FRAME_POINTERS select ARCH_HAS_ELF_RANDOMIZE + select ARCH_HAS_STRICT_KERNEL_RWX select RTC_CLASS select RTC_DRV_GENERIC select INIT_ALL_POSSIBLE diff --git a/arch/parisc/Kconfig.debug b/arch/parisc/Kconfig.debug index 68b7cbd..0d856b9 100644 --- a/arch/parisc/Kconfig.debug +++ b/arch/parisc/Kconfig.debug @@ -5,15 +5,4 @@ source "lib/Kconfig.debug" config TRACE_IRQFLAGS_SUPPORT def_bool y -config DEBUG_RODATA - bool "Write protect kernel read-only data structures" - depends on DEBUG_KERNEL - default y - help - Mark the kernel read-only data as write-protected in the pagetables, - in order to catch accidental (and incorrect) writes to such const - data. This option may have a slight performance impact because a - portion of the kernel code won't be covered by a TLB anymore. - If in doubt, say "N". - endmenu diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index c6722112..53bb0e3 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -62,9 +62,6 @@ config PCI_QUIRKS config ARCH_SUPPORTS_UPROBES def_bool y -config DEBUG_RODATA - def_bool y - config S390 def_bool y select ARCH_HAS_DEVMEM_IS_ALLOWED @@ -73,6 +70,8 @@ config S390 select ARCH_HAS_GIGANTIC_PAGE select ARCH_HAS_KCOV select ARCH_HAS_SG_CHAIN + select ARCH_HAS_STRICT_KERNEL_RWX + select ARCH_HAS_STRICT_MODULE_RWX select ARCH_HAS_UBSAN_SANITIZE_ALL select ARCH_HAVE_NMI_SAFE_CMPXCHG select ARCH_INLINE_READ_LOCK diff --git a/arch/s390/Kconfig.debug b/arch/s390/Kconfig.debug index 26c5d5be..57f8ea9 100644 --- a/arch/s390/Kconfig.debug +++ b/arch/s390/Kconfig.debug @@ -17,7 +17,4 @@ config S390_PTDUMP kernel. If in doubt, say "N" -config DEBUG_SET_MODULE_RONX - def_bool y - depends on MODULES endmenu diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index e487493..13e1bf4 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -54,6 +54,8 @@ config X86 select ARCH_HAS_MMIO_FLUSH select ARCH_HAS_PMEM_API if X86_64 select ARCH_HAS_SG_CHAIN + select ARCH_HAS_STRICT_KERNEL_RWX + select ARCH_HAS_STRICT_MODULE_RWX select ARCH_HAS_UBSAN_SANITIZE_ALL select ARCH_HAVE_NMI_SAFE_CMPXCHG select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI @@ -309,9 +311,6 @@ config ARCH_SUPPORTS_UPROBES config FIX_EARLYCON_MEM def_bool y -config DEBUG_RODATA - def_bool y - config PGTABLE_LEVELS int default 4 if X86_64 diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug index 67eec55..69cdd0b 100644 --- a/arch/x86/Kconfig.debug +++ b/arch/x86/Kconfig.debug @@ -109,17 +109,6 @@ config DEBUG_WX If in doubt, say "Y". -config DEBUG_SET_MODULE_RONX - bool "Set loadable kernel module data as NX and text as RO" - depends on MODULES - ---help--- - This option helps catch unintended modifications to loadable - kernel module's text and read-only data. It also prevents execution - of module data. Such protection may interfere with run-time code - patching and dynamic kernel tracing - and they might also protect - against certain classes of kernel exploits. - If in doubt, say "N". - config DEBUG_NX_TEST tristate "Testcase for the NX non-executable stack feature" depends on DEBUG_KERNEL && m -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
