* jeffxu@chromium.org jeffxu@chromium.org [250303 00:09]:

From: Jeff Xu jeffxu@chromium.org

Update memory sealing documentation to include details about system mappings.

Signed-off-by: Jeff Xu jeffxu@chromium.org Reviewed-by: Kees Cook kees@kernel.org

Reviewed-by: Liam R. Howlett Liam.Howlett@oracle.com

---

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