mm/mseal: fix mseal documentation for 32-bit kernels
Subsystems (3)
PATCH v2 1/1 mm/mseal: fix mseal documentation for 32-bit kernels
mseal.o is built only for 64-bit kernels, so 32-bit kernels fall back to sys_ni_syscall() and return -ENOSYS rather than -EPERM.
Drop architecture description in mseal.rst, since the arch feature doc has the latest state of mseal for each architecture.
Fix the CONFIG_MSEAL_SYSTEM_MAPPINGS typo in init/Kconfig.
Drop the whole comment of do_mseal() to avoid stale info in the comment, as we have the doc in mseal.rst.
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v1 -> v2:
* Drop -EINTR description in mseal.rst. (per Mathew)
* Drop VM_SEALED_SYSMAP change in mseal.rst. (per Pedro)
* Drop architecture description in mseal.rst. (per Pedro)
* Drop the whole comment of do_mseal(). (per Pedro)
* v1: https://lore.kernel.org/linux-mm/[email protected]/
--- Documentation/userspace-api/mseal.rst | 14 ++++---- init/Kconfig | 2 +- mm/mseal.c | 52 --------------------------- 3 files changed, 7 insertions(+), 61 deletions(-)
Documentation/userspace-api/mseal.rst +6 -8
@@ -50,8 +50,8 @@ mseal syscall signature * The start address (``addr``) is not allocated. * The end address (``addr`` + ``len``) is not allocated. * A gap (unallocated memory) between start and end address. - - **-EPERM**: - * sealing is supported only on 64-bit CPUs, 32-bit is not supported. + - **-ENOSYS**: + * The kernel does not implement ``mseal()``. **Note about error return**: - For above error cases, users can expect the given memory range is
@@ -62,7 +62,8 @@ mseal syscall signature memory range could happen. However, those cases should be rare. **Architecture support**: - mseal only works on 64-bit CPUs, not 32-bit CPUs. + mseal is built only for 64-bit kernels. 32-bit kernels return + ``-ENOSYS``. **Idempotent**: users can call mseal multiple times. mseal on an already sealed memory
@@ -131,11 +132,11 @@ Use cases - Chrome browser: protect some security sensitive data structures. - System mappings: - The system mappings are created by the kernel and includes vdso, vvar, + The system mappings are created by the kernel and include 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 + protect them from ever changing to writable or unmapped/remapped as different attributes. This is useful to mitigate memory corruption issues where a corrupted pointer is passed to a memory management system.
@@ -143,9 +144,6 @@ Use cases 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
init/Kconfig +1 -1
@@ -2120,7 +2120,7 @@ config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS from a kernel perspective. After the architecture enables this, a distribution can set - CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature. + CONFIG_MSEAL_SYSTEM_MAPPINGS to manage access to the feature. For complete descriptions of memory sealing, please see Documentation/userspace-api/mseal.rst
mm/mseal.c +0 -52
58 lines not on this page · raw message
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2.55.0