Hi
This is v4 of the File-Sealing and memfd_create() patches. You can find v1 with
a longer introduction at gmane [1], there's also v2 [2] and v3 [3] available.
See also the article about sealing on LWN [4], and a high-level introduction on
the new API in my blog [5]. Last but not least, man-page proposals are
available in my private repository [6].
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 those operations will be rejected from now on.
This series adds the memfd_create(2) syscall only to x86 and x86-64. Patches for
most other architectures are available in my private repository [7]. Missing
architectures are:
alpha, avr32, blackfin, cris, frv, m32r, microblaze, mn10300, sh, sparc,
um, xtensa
These architectures lack several newer syscalls, so those should be added first
before adding memfd_create(2). I can provide patches for those, if required.
However, I think it should be kept separate from this series.
Changes in v4:
- drop page-isolation in favor of shmem_wait_for_pins()
- add unlikely(info->seals) to write_begin hot-path
- return EPERM for F_ADD_SEALS if file is not writable
- moved shmem_wait_for_pins() entirely into it's own commit
- make O_LARGEFILE mandatory part of memfd_create() ABI
- add lru_add_drain() to shmem_tag_pins() hot-path
- minor coding-style changes
Thanks
David
[1] memfd v1: http://thread.gmane.org/gmane.comp.video.dri.devel/102241
[2] memfd v2: http://thread.gmane.org/gmane.linux.kernel.mm/115713
[3] memfd v3: http://thread.gmane.org/gmane.linux.kernel.mm/118721
[4] LWN article: https://lwn.net/Articles/593918/
[5] API Intro: http://dvdhrm.wordpress.com/2014/06/10/memfd_create2/
[6] Man-pages: http://cgit.freedesktop.org/~dvdhrm/man-pages/log/?h=memfd
[7] Dev-repo: http://cgit.freedesktop.org/~dvdhrm/linux/log/?h=memfd
David Herrmann (6):
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
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 | 30 +-
mm/shmem.c | 324 +++++++++
mm/swap_state.c | 1 +
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/memfd/.gitignore | 4 +
tools/testing/selftests/memfd/Makefile | 41 ++
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, 1821 insertions(+), 9 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
--
2.0.2
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