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Diffstat (limited to 'Documentation/userspace-api/mseal.rst')
| -rw-r--r-- | Documentation/userspace-api/mseal.rst | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/Documentation/userspace-api/mseal.rst b/Documentation/userspace-api/mseal.rst index 41102f74c5e2..ea9b11a0bd89 100644 --- a/Documentation/userspace-api/mseal.rst +++ b/Documentation/userspace-api/mseal.rst @@ -27,7 +27,7 @@ SYSCALL ======= mseal syscall signature ----------------------- - ``int mseal(void \* addr, size_t len, unsigned long flags)`` + ``int mseal(void *addr, size_t len, unsigned long flags)`` **addr**/**len**: virtual memory address range. The address range set by **addr**/**len** must meet: @@ -130,6 +130,27 @@ 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 compat-mode), sigpage (arm compat-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, arm64, + loongarch and s390. + + 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, |