| Message ID | 20241125202021.3684919-1-jeffxu@google.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Seal system mappings | expand |
+Vlastimil Jeff... :) Please review https://www.kernel.org/doc/html/latest/process/submitting-patches.html You didn't cc- mantainers of code you are changing. And you reference my name without cc'ing me here. I'm sure there's some relevant Taylor Swift lyric... On Mon, Nov 25, 2024 at 08:20:20PM +0000, jeffxu@chromium.org wrote: > From: Jeff Xu <jeffxu@chromium.org> > > Seal vdso, vvar, sigpage, uprobes and vsyscall. > > Those mappings are readonly or executable only, sealing can protect > them from ever changing or unmapped during the life time of the process. > For complete descriptions of memory sealing, please see mseal.rst [1]. > > System mappings such as vdso, vvar, and sigpage (for arm) are > generated by the kernel during program initialization, and are > sealed after creation. > > Unlike the aforementioned mappings, the uprobe mapping is not > established during program startup. However, its lifetime is the same > as the process's lifetime [2]. It is sealed from creation. > > The vdso, vvar, sigpage, and uprobe mappings all invoke the > _install_special_mapping() function. As no other mappings utilize this > function, it is logical to incorporate sealing logic within > _install_special_mapping(). This approach avoids the necessity of > modifying code across various architecture-specific implementations. > > The vsyscall mapping, which has its own initialization function, is > sealed in the XONLY case, it seems to be the most common and secure > case of using vsyscall. > > It is important to note that the CHECKPOINT_RESTORE feature (CRIU) may > alter the mapping of vdso, vvar, and sigpage during restore > operations. Consequently, this feature cannot be universally enabled > across all systems. > > Currently, memory sealing is only functional in a 64-bit kernel > configuration. > > To enable this feature, the architecture needs to be tested to > confirm that it doesn't unmap/remap system mappings during the > the life time of the process. After the architecture enables > ARCH_HAS_SEAL_SYSTEM_MAPPINGS, a distribution can set > CONFIG_SEAL_SYSTEM_MAPPING to manage access to the feature. > Alternatively, kernel command line (exec.seal_system_mappings) > enables this feature also. > > This feature is tested using ChromeOS and Android on X86_64 and ARM64, > therefore ARCH_HAS_SEAL_SYSTEM_MAPPINGS is set for X86_64 and ARM64. > Other architectures can enable this after testing. No specific hardware > features from the CPU are needed. > > This feature's security enhancements will benefit ChromeOS, Android, > and other secure-by-default systems. > > [1] Documentation/userspace-api/mseal.rst > [2] https://lore.kernel.org/all/CABi2SkU9BRUnqf70-nksuMCQ+yyiWjo3fM4XkRkL-NrCZxYAyg@mail.gmail.com/ > > History: > V4: > ARCH_HAS_SEAL_SYSTEM_MAPPINGS (Lorenzo Stoakes) > test info (Lorenzo Stoakes) > Update mseal.rst (Liam R. Howlett) > Update test_mremap_vdso.c (Liam R. Howlett) > Misc. style, comments, doc update (Liam R. Howlett) > > V3: > https://lore.kernel.org/all/20241113191602.3541870-1-jeffxu@google.com/ > Revert uprobe to v1 logic (Oleg Nesterov) > use CONFIG_SEAL_SYSTEM_MAPPINGS instead of _ALWAYS/_NEVER (Kees Cook) > Move kernel cmd line from fs/exec.c to mm/mseal.c and misc. refactor (Liam R. Howlett) > > V2: > https://lore.kernel.org/all/20241014215022.68530-1-jeffxu@google.com/ > Seal uprobe always (Oleg Nesterov) > Update comments and description (Randy Dunlap, Liam R.Howlett, Oleg Nesterov) > Rebase to linux_main > > V1: > https://lore.kernel.org/all/20241004163155.3493183-1-jeffxu@google.com/ > > Jeff Xu (1): > exec: seal system mappings > > .../admin-guide/kernel-parameters.txt | 11 ++++++ > Documentation/userspace-api/mseal.rst | 4 ++ > arch/arm64/Kconfig | 1 + > arch/x86/Kconfig | 1 + > arch/x86/entry/vsyscall/vsyscall_64.c | 8 +++- > include/linux/mm.h | 12 ++++++ > init/Kconfig | 25 ++++++++++++ > mm/mmap.c | 10 +++++ > mm/mseal.c | 39 +++++++++++++++++++ > security/Kconfig | 24 ++++++++++++ > 10 files changed, 133 insertions(+), 2 deletions(-) > > -- > 2.47.0.338.g60cca15819-goog >
From: Jeff Xu <jeffxu@chromium.org> Seal vdso, vvar, sigpage, uprobes and vsyscall. Those mappings are readonly or executable only, sealing can protect them from ever changing or unmapped during the life time of the process. For complete descriptions of memory sealing, please see mseal.rst [1]. System mappings such as vdso, vvar, and sigpage (for arm) are generated by the kernel during program initialization, and are sealed after creation. Unlike the aforementioned mappings, the uprobe mapping is not established during program startup. However, its lifetime is the same as the process's lifetime [2]. It is sealed from creation. The vdso, vvar, sigpage, and uprobe mappings all invoke the _install_special_mapping() function. As no other mappings utilize this function, it is logical to incorporate sealing logic within _install_special_mapping(). This approach avoids the necessity of modifying code across various architecture-specific implementations. The vsyscall mapping, which has its own initialization function, is sealed in the XONLY case, it seems to be the most common and secure case of using vsyscall. It is important to note that the CHECKPOINT_RESTORE feature (CRIU) may alter the mapping of vdso, vvar, and sigpage during restore operations. Consequently, this feature cannot be universally enabled across all systems. Currently, memory sealing is only functional in a 64-bit kernel configuration. To enable this feature, the architecture needs to be tested to confirm that it doesn't unmap/remap system mappings during the the life time of the process. After the architecture enables ARCH_HAS_SEAL_SYSTEM_MAPPINGS, a distribution can set CONFIG_SEAL_SYSTEM_MAPPING to manage access to the feature. Alternatively, kernel command line (exec.seal_system_mappings) enables this feature also. This feature is tested using ChromeOS and Android on X86_64 and ARM64, therefore ARCH_HAS_SEAL_SYSTEM_MAPPINGS is set for X86_64 and ARM64. Other architectures can enable this after testing. No specific hardware features from the CPU are needed. This feature's security enhancements will benefit ChromeOS, Android, and other secure-by-default systems. [1] Documentation/userspace-api/mseal.rst [2] https://lore.kernel.org/all/CABi2SkU9BRUnqf70-nksuMCQ+yyiWjo3fM4XkRkL-NrCZxYAyg@mail.gmail.com/ History: V4: ARCH_HAS_SEAL_SYSTEM_MAPPINGS (Lorenzo Stoakes) test info (Lorenzo Stoakes) Update mseal.rst (Liam R. Howlett) Update test_mremap_vdso.c (Liam R. Howlett) Misc. style, comments, doc update (Liam R. Howlett) V3: https://lore.kernel.org/all/20241113191602.3541870-1-jeffxu@google.com/ Revert uprobe to v1 logic (Oleg Nesterov) use CONFIG_SEAL_SYSTEM_MAPPINGS instead of _ALWAYS/_NEVER (Kees Cook) Move kernel cmd line from fs/exec.c to mm/mseal.c and misc. refactor (Liam R. Howlett) V2: https://lore.kernel.org/all/20241014215022.68530-1-jeffxu@google.com/ Seal uprobe always (Oleg Nesterov) Update comments and description (Randy Dunlap, Liam R.Howlett, Oleg Nesterov) Rebase to linux_main V1: https://lore.kernel.org/all/20241004163155.3493183-1-jeffxu@google.com/ Jeff Xu (1): exec: seal system mappings .../admin-guide/kernel-parameters.txt | 11 ++++++ Documentation/userspace-api/mseal.rst | 4 ++ arch/arm64/Kconfig | 1 + arch/x86/Kconfig | 1 + arch/x86/entry/vsyscall/vsyscall_64.c | 8 +++- include/linux/mm.h | 12 ++++++ init/Kconfig | 25 ++++++++++++ mm/mmap.c | 10 +++++ mm/mseal.c | 39 +++++++++++++++++++ security/Kconfig | 24 ++++++++++++ 10 files changed, 133 insertions(+), 2 deletions(-)