Christain, A little while ago, Jan and I realized that an unprivileged overlayfs mount could be used to avert fanotify permission events that were requested for an inode or sb on the underlying fs. The [v1] patch set was an attempt to implement Miklos' suggestion (opt-in to query the fake path) which turned out to affet the vfs in many places, so Miklos and I agreed on a solution that will be less intrusive for vfs (opt-in to query the real path). The [v2] patch set took the less intrusive approach to vfs, but it also tried a different approach of extending the d_real() interface, which Miklos did not like. The [v3] patch goes back to the less intrusive approach to vfs without complicating d_real() interface, that Miklso and I agreed on during the [v1] patch set review, so hopefully everyone can be happy with it. This v4 patch set addresses review comments from yourself and from Christoph on [v3]. Since the patches are 95% vfs, I think it is better if they are merged through the vfs tree. I am hoping to solicit an ACK from Jan and Miklos on the minor changes in ovl and fsnotify in the 2nd patch. Thanks, Amir. Changes since [v3]: - Rename struct file_fake to backing_file - Rename helpers to open_backing_file(), backing_file_real_path() - Rename FMODE_FAKE_PATH to FMODE_BACKING - Separate flag from FMODE_NOACCOUNT - inline the fast-path branch of f_real_path() Changes since [v2]: - Restore the file_fake container (Miklos) - Re-arrange the v1 helpers (Christian) Changes since [v1]: - Drop the file_fake container - Leave f_path fake and special case only fsnotify [v3] https://lore.kernel.org/linux-unionfs/20230611194706.1583818-1-amir73il@xxxxxxxxx/ [v2] https://lore.kernel.org/linux-unionfs/20230611132732.1502040-1-amir73il@xxxxxxxxx/ [v1] https://lore.kernel.org/linux-unionfs/20230609073239.957184-1-amir73il@xxxxxxxxx/ Amir Goldstein (2): fs: use backing_file container for internal files with "fake" f_path ovl: enable fsnotify events on underlying real files fs/cachefiles/namei.c | 4 +-- fs/file_table.c | 74 +++++++++++++++++++++++++++++++++++----- fs/internal.h | 5 +-- fs/open.c | 30 +++++++++------- fs/overlayfs/file.c | 8 ++--- include/linux/fs.h | 24 ++++++++++--- include/linux/fsnotify.h | 3 +- 7 files changed, 113 insertions(+), 35 deletions(-) -- 2.34.1
