From: Jeff Xu <jeffxu@xxxxxxxxxxxx> Update memory sealing documentation to include details about system mappings. Signed-off-by: Jeff Xu <jeffxu@xxxxxxxxxxxx> Reviewed-by: Kees Cook <kees@xxxxxxxxxx> --- Documentation/userspace-api/mseal.rst | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/Documentation/userspace-api/mseal.rst b/Documentation/userspace-api/mseal.rst index 41102f74c5e2..76e10938302a 100644 --- a/Documentation/userspace-api/mseal.rst +++ b/Documentation/userspace-api/mseal.rst @@ -130,6 +130,26 @@ Use cases - Chrome browser: protect some security sensitive data structures. +- System mappings: + The system mappings are created by the kernel and includes vdso, vvar, + vvar_vclock, vectors (arm compact-mode), sigpage (arm compact-mode), uprobes. + + Those system mappings are readonly only or execute only, memory sealing can + protect them from ever changing to writable or unmmap/remapped as different + attributes. This is useful to mitigate memory corruption issues where a + corrupted pointer is passed to a memory management system. + + If supported by an architecture (CONFIG_ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS), + the CONFIG_MSEAL_SYSTEM_MAPPINGS seals all system mappings of this + architecture. + + The following architectures currently support this feature: x86-64 and arm64. + + 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. + When not to use mseal ===================== Applications can apply sealing to any virtual memory region from userspace, -- 2.48.1.711.g2feabab25a-goog
