From: Jeff Xu jeffxu@chromium.org
Provide infrastructure to mseal system mappings. Establish two kernel configs (CONFIG_MSEAL_SYSTEM_MAPPINGS, ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS) and VM_SEALED_SYSMAP macro for future patches.
Signed-off-by: Jeff Xu jeffxu@chromium.org --- include/linux/mm.h | 10 ++++++++++ init/Kconfig | 22 ++++++++++++++++++++++ security/Kconfig | 21 +++++++++++++++++++++ 3 files changed, 53 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h index 7b1068ddcbb7..8b800941678d 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4155,4 +4155,14 @@ int arch_get_shadow_stack_status(struct task_struct *t, unsigned long __user *st int arch_set_shadow_stack_status(struct task_struct *t, unsigned long status); int arch_lock_shadow_stack_status(struct task_struct *t, unsigned long status);
+ +/* + * mseal of userspace process's system mappings. + */ +#ifdef CONFIG_MSEAL_SYSTEM_MAPPINGS +#define VM_SEALED_SYSMAP VM_SEALED +#else +#define VM_SEALED_SYSMAP VM_NONE +#endif + #endif /* _LINUX_MM_H */ diff --git a/init/Kconfig b/init/Kconfig index d0d021b3fa3b..c90dd8778993 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1882,6 +1882,28 @@ config ARCH_HAS_MEMBARRIER_CALLBACKS config ARCH_HAS_MEMBARRIER_SYNC_CORE bool
+config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS + bool + help + Control MSEAL_SYSTEM_MAPPINGS access based on architecture. + + A 64-bit kernel is required for the memory sealing feature. + No specific hardware features from the CPU are needed. + + To enable this feature, the architecture needs to update their + special mappings calls to include the sealing flag and confirm + that it doesn't unmap/remap system mappings during the life + time of the process. The existence of this flag for an architecture + implies that it does not require the remapping of thest system + mappings during process lifetime, so sealing these mappings is safe + from a kernel perspective. + + After the architecture enables this, a distribution can set + CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature. + + For complete descriptions of memory sealing, please see + Documentation/userspace-api/mseal.rst + config HAVE_PERF_EVENTS bool help diff --git a/security/Kconfig b/security/Kconfig index f10dbf15c294..5311f4a6786c 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -51,6 +51,27 @@ config PROC_MEM_NO_FORCE
endchoice
+config MSEAL_SYSTEM_MAPPINGS + bool "mseal system mappings" + depends on 64BIT + depends on ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS + depends on !CHECKPOINT_RESTORE + help + Apply mseal on system mappings. + The system mappings includes vdso, vvar, vvar_vclock, + vectors (arm compact-mode), sigpage (arm compact-mode), uprobes. + + A 64-bit kernel is required for the memory sealing feature. + No specific hardware features from the CPU are needed. + + WARNING: This feature breaks programs which rely on relocating + or unmapping system mappings. Known broken software at the time + of writing includes CHECKPOINT_RESTORE, UML, gVisor, rr. Therefore + this config can't be enabled universally. + + For complete descriptions of memory sealing, please see + Documentation/userspace-api/mseal.rst + config SECURITY bool "Enable different security models" depends on SYSFS