Hi This is v3 of the File-Sealing and memfd_create() patches. You can find v1 with a longer introduction at gmane: http://thread.gmane.org/gmane.comp.video.dri.devel/102241 An LWN article about memfd+sealing is available, too: https://lwn.net/Articles/593918/ v2 with some more discussions can be found here: http://thread.gmane.org/gmane.linux.kernel.mm/115713 This series introduces two new APIs: memfd_create(): Think of this syscall as malloc() but it returns a file-descriptor instead of a pointer. That file-descriptor is backed by anon-memory and can be memory-mapped for access. sealing: The sealing API can be used to prevent a specific set of operations on a file-descriptor. You 'seal' the file and give thus the guarantee, that it cannot be modified in the specific ways. A short high-level introduction is also available here: http://dvdhrm.wordpress.com/2014/06/10/memfd_create2/ Changed in v3: - fcntl() now returns EINVAL if the FD does not support sealing. We used to return EBADF like pipe_fcntl() does, but that is really weird and I don't like repeating that. - seals are now saved as "unsigned int" instead of "u32". - i_mmap_writable is now an atomic so we can deny writable mappings just like i_writecount does. - SHMEM_ALLOW_SEALING is dropped. We initialize all objects with F_SEAL_SEAL and only unset it for memfds that shall support sealing. - memfd_create() no longer has a size argument. It was redundant, use ftruncate() or fallocate(). - memfd_create() flags are "unsigned int" now, instead of "u64". - NAME_MAX off-by-one fix - several cosmetic changes - Added AIO/Direct-IO page-pinning protection The last point is the most important change in this version: We now bail out if any page-refcount is elevated while setting SEAL_WRITE. This prevents parallel GUP users from writing to sealed files _after_ they were sealed. There is also a new FUSE-based test-case to trigger such situations. The last 2 patches try to improve the page-pinning handling. I included both in this series, but obviously only one of them is needed (or we could stack them): - 6/7: This waits for up to 150ms for pages to be unpinned - 7/7: This isolates pinned pages and replaces them with a fresh copy Hugh, patch 6 is basically your code. In case that gets merged, can I put your Signed-off-by on it? I hope I didn't miss anything. Further comments welcome! Thanks David David Herrmann (7): mm: allow drivers to prevent new writable mappings shm: add sealing API shm: add memfd_create() syscall selftests: add memfd_create() + sealing tests selftests: add memfd/sealing page-pinning tests shm: wait for pins to be released when sealing shm: isolate pinned pages when sealing files arch/x86/syscalls/syscall_32.tbl | 1 + arch/x86/syscalls/syscall_64.tbl | 1 + fs/fcntl.c | 5 + fs/inode.c | 1 + include/linux/fs.h | 29 +- include/linux/shmem_fs.h | 17 + include/linux/syscalls.h | 1 + include/uapi/linux/fcntl.h | 15 + include/uapi/linux/memfd.h | 8 + kernel/fork.c | 2 +- kernel/sys_ni.c | 1 + mm/mmap.c | 24 +- mm/shmem.c | 320 ++++++++- mm/swap_state.c | 1 + tools/testing/selftests/Makefile | 1 + tools/testing/selftests/memfd/.gitignore | 4 + tools/testing/selftests/memfd/Makefile | 40 ++ tools/testing/selftests/memfd/fuse_mnt.c | 110 +++ tools/testing/selftests/memfd/fuse_test.c | 311 +++++++++ tools/testing/selftests/memfd/memfd_test.c | 913 +++++++++++++++++++++++++ tools/testing/selftests/memfd/run_fuse_test.sh | 14 + 21 files changed, 1807 insertions(+), 12 deletions(-) create mode 100644 include/uapi/linux/memfd.h create mode 100644 tools/testing/selftests/memfd/.gitignore create mode 100644 tools/testing/selftests/memfd/Makefile create mode 100755 tools/testing/selftests/memfd/fuse_mnt.c create mode 100644 tools/testing/selftests/memfd/fuse_test.c create mode 100644 tools/testing/selftests/memfd/memfd_test.c create mode 100755 tools/testing/selftests/memfd/run_fuse_test.sh -- 2.0.0 -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
