kernel/linux.git/fs/overlayfs/export.c, branch v6.6.133

ovl: support encoding fid from inode with no alias

2025-01-23T16:21:19+00:00

commit c45beebfde34aa71afbc48b2c54cdda623515037 upstream. Dmitry Safonov reported that a WARN_ON() assertion can be trigered by userspace when calling inotify_show_fdinfo() for an overlayfs watched inode, whose dentry aliases were discarded with drop_caches. The WARN_ON() assertion in inotify_show_fdinfo() was removed, because it is possible for encoding file handle to fail for other reason, but the impact of failing to encode an overlayfs file handle goes beyond this assertion. As shown in the LTP test case mentioned in the link below, failure to encode an overlayfs file handle from a non-aliased inode also leads to failure to report an fid with FAN_DELETE_SELF fanotify events. As Dmitry notes in his analyzis of the problem, ovl_encode_fh() fails if it cannot find an alias for the inode, but this failure can be fixed. ovl_encode_fh() seldom uses the alias and in the case of non-decodable file handles, as is often the case with fanotify fid info, ovl_encode_fh() never needs to use the alias to encode a file handle. Defer finding an alias until it is actually needed so ovl_encode_fh() will not fail in the common case of FAN_DELETE_SELF fanotify events. Fixes: 16aac5ad1fa9 ("ovl: support encoding non-decodable file handles") Reported-by: Dmitry Safonov Closes: https://lore.kernel.org/linux-fsdevel/CAOQ4uxiie81voLZZi2zXS1BziXZCM24nXqPAxbu8kxXCUWdwOg@mail.gmail.com/ Signed-off-by: Amir Goldstein Link: https://lore.kernel.org/r/20250105162404.357058-3-amir73il@gmail.com Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ovl: pass realinode to ovl_encode_real_fh() instead of realdentry

2025-01-23T16:21:18+00:00

commit 07aeefae7ff44d80524375253980b1bdee2396b0 upstream. We want to be able to encode an fid from an inode with no alias. Signed-off-by: Amir Goldstein Link: https://lore.kernel.org/r/20250105162404.357058-2-amir73il@gmail.com Signed-off-by: Christian Brauner Stable-dep-of: c45beebfde34 ("ovl: support encoding fid from inode with no alias") Signed-off-by: Sasha Levin [re-applied over v6.6.71 with conflict resolved] Signed-off-by: Amir Goldstein Signed-off-by: Greg Kroah-Hartman

Revert "ovl: pass realinode to ovl_encode_real_fh() instead of realdentry"

2025-01-21T08:49:10+00:00

This reverts commit a3f8a2b13a277d942c810d2ccc654d5bc824a430 which is commit 07aeefae7ff44d80524375253980b1bdee2396b0 upstream. It is reported to part of a series that causes problems in the 6.6.y tree, so revert it at this point in time and it can come back later if still needed. Reported-by: Ignat Korchagin Link: https://lore.kernel.org/r/ACD4D6CC-C4D5-4657-A805-03C34559046E@cloudflare.com Cc: Dmitry Safonov Cc: Amir Goldstein Cc: Christian Brauner Cc: Sasha Levin Signed-off-by: Greg Kroah-Hartman

Revert "ovl: support encoding fid from inode with no alias"

2025-01-21T08:49:09+00:00

This reverts commit a1a541fbfa7e97c1100144db34b57553d7164ce5 which is commit c45beebfde34aa71afbc48b2c54cdda623515037 upstream. It is reported to part of a series that causes problems in the 6.6.y tree, so revert it at this point in time and it can come back later if still needed. Reported-by: Ignat Korchagin Link: https://lore.kernel.org/r/ACD4D6CC-C4D5-4657-A805-03C34559046E@cloudflare.com Cc: Dmitry Safonov Cc: Amir Goldstein Cc: Christian Brauner Cc: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ovl: support encoding fid from inode with no alias

2025-01-17T12:36:10+00:00

[ Upstream commit c45beebfde34aa71afbc48b2c54cdda623515037 ] Dmitry Safonov reported that a WARN_ON() assertion can be trigered by userspace when calling inotify_show_fdinfo() for an overlayfs watched inode, whose dentry aliases were discarded with drop_caches. The WARN_ON() assertion in inotify_show_fdinfo() was removed, because it is possible for encoding file handle to fail for other reason, but the impact of failing to encode an overlayfs file handle goes beyond this assertion. As shown in the LTP test case mentioned in the link below, failure to encode an overlayfs file handle from a non-aliased inode also leads to failure to report an fid with FAN_DELETE_SELF fanotify events. As Dmitry notes in his analyzis of the problem, ovl_encode_fh() fails if it cannot find an alias for the inode, but this failure can be fixed. ovl_encode_fh() seldom uses the alias and in the case of non-decodable file handles, as is often the case with fanotify fid info, ovl_encode_fh() never needs to use the alias to encode a file handle. Defer finding an alias until it is actually needed so ovl_encode_fh() will not fail in the common case of FAN_DELETE_SELF fanotify events. Fixes: 16aac5ad1fa9 ("ovl: support encoding non-decodable file handles") Reported-by: Dmitry Safonov Closes: https://lore.kernel.org/linux-fsdevel/CAOQ4uxiie81voLZZi2zXS1BziXZCM24nXqPAxbu8kxXCUWdwOg@mail.gmail.com/ Signed-off-by: Amir Goldstein Link: https://lore.kernel.org/r/20250105162404.357058-3-amir73il@gmail.com Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

ovl: pass realinode to ovl_encode_real_fh() instead of realdentry

2025-01-17T12:36:10+00:00

[ Upstream commit 07aeefae7ff44d80524375253980b1bdee2396b0 ] We want to be able to encode an fid from an inode with no alias. Signed-off-by: Amir Goldstein Link: https://lore.kernel.org/r/20250105162404.357058-2-amir73il@gmail.com Signed-off-by: Christian Brauner Stable-dep-of: c45beebfde34 ("ovl: support encoding fid from inode with no alias") Signed-off-by: Sasha Levin

ovl: fix encoding fid for lower only root

2024-06-27T11:49:12+00:00

commit 004b8d1491b4bcbb7da1a3206d1e7e66822d47c6 upstream. ovl_check_encode_origin() should return a positive number if the lower dentry is to be encoded, zero otherwise. If there's no upper layer at all (read-only overlay), then it obviously needs to return positive. This was broken by commit 16aac5ad1fa9 ("ovl: support encoding non-decodable file handles"), which didn't take the lower-only configuration into account. Fix by checking the no-upper-layer case up-front. Reported-and-tested-by: Youzhong Yang Closes: https://lore.kernel.org/all/CADpNCvaBimi+zCYfRJHvCOhMih8OU0rmZkwLuh24MKKroRuT8Q@mail.gmail.com/ Fixes: 16aac5ad1fa9 ("ovl: support encoding non-decodable file handles") Cc: # v6.6 Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

ovl: fix NULL pointer defer when encoding non-decodable lower fid

2023-10-03T06:24:11+00:00

A wrong return value from ovl_check_encode_origin() would cause ovl_dentry_to_fid() to try to encode fid from NULL upper dentry. Reported-by: syzbot+2208f82282740c1c8915@syzkaller.appspotmail.com Fixes: 16aac5ad1fa9 ("ovl: support encoding non-decodable file handles") Signed-off-by: Amir Goldstein

ovl: make consistent use of OVL_FS()

2023-08-12T16:02:54+00:00

Always use OVL_FS() to retrieve the corresponding struct ovl_fs from a struct super_block. Reviewed-by: Amir Goldstein Signed-off-by: Andrea Righi Signed-off-by: Amir Goldstein

ovl: support encoding non-decodable file handles

2023-08-12T16:02:47+00:00

When all layers support file handles, we support encoding non-decodable file handles (a.k.a. fid) even with nfs_export=off. When file handles do not need to be decoded, we do not need to copy up redirected lower directories on encode, and we encode also non-indexed upper with lower file handle, so fid will not change on copy up. This enables reporting fanotify events with file handles on overlayfs with default config/mount options. Signed-off-by: Amir Goldstein