[PATCH 00/15] Tidy up file permission hooks

Amir Goldstein
2023-11-14T15:33:03Z

Hi Christian,

I realize you won't have time to review this week, but wanted to get
this series out for review for a wider audience soon.

During my work on fanotify "pre content" events [1], Jan and I noticed
some inconsistencies in the call sites of security_file_permission()
hooks inside rw_verify_area() and remap_verify_area().

The majority of call sites are before file_start_write(), which is how
we want them to be for fanotify "pre content" events.

For splice code, there are many duplicate calls to rw_verify_area()
for the entire range as well as for partial ranges inside iterator.

This cleanup series, mostly following Jan's suggestions, moves all
the security_file_permission() hooks before file_start_write() and
eliminates duplicate permission hook calls in the same call chain.

The last 3 patches are helpers that I used in fanotify patches to
assert that permission hooks are called with expected locking scope.

My hope is to get this work reviewed and staged in the vfs tree
for the 6.8 cycle, so that I can send Jan fanotify patches for
"pre content" events based on a stable branch in the vfs tree.

Thanks,
Amir.

[1] https://github.com/amir73il/linux/commits/fan_pre_content

Amir Goldstein (15):
ovl: add permission hooks outside of do_splice_direct()
splice: remove permission hook from do_splice_direct()
splice: move permission hook out of splice_direct_to_actor()
splice: move permission hook out of splice_file_to_pipe()
splice: remove permission hook from iter_file_splice_write()
remap_range: move permission hooks out of do_clone_file_range()
remap_range: move file_start_write() to after permission hook
btrfs: move file_start_write() to after permission hook
fs: move file_start_write() into vfs_iter_write()
fs: move permission hook out of do_iter_write()
fs: move permission hook out of do_iter_read()
fs: move kiocb_start_write() into vfs_iocb_iter_write()
fs: create __sb_write_started() helper
fs: create file_write_started() helper
fs: create {sb,file}_write_not_started() helpers

drivers/block/loop.c | 2 -
fs/btrfs/ioctl.c | 12 +--
fs/cachefiles/io.c | 2 -
fs/coda/file.c | 4 +-
fs/internal.h | 8 +-
fs/nfsd/vfs.c | 7 +-
fs/overlayfs/copy_up.c | 26 ++++++-
fs/overlayfs/file.c | 3 -
fs/read_write.c | 164 +++++++++++++++++++++++++++--------------
fs/remap_range.c | 48 ++++++------
fs/splice.c | 78 ++++++++++++--------
include/linux/fs.h | 62 +++++++++++++++-
12 files changed, 279 insertions(+), 137 deletions(-)

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2.34.1