Max Kellermann f4dce08ba1 fs/kernfs/dir: obey S_ISGID
[ Upstream commit 5133bee62f0ea5d4c316d503cc0040cac5637601 ]

Handling of S_ISGID is usually done by inode_init_owner() in all other
filesystems, but kernfs doesn't use that function.  In kernfs, struct
kernfs_node is the primary data structure, and struct inode is only
created from it on demand.  Therefore, inode_init_owner() can't be
used and we need to imitate its behavior.

S_ISGID support is useful for the cgroup filesystem; it allows
subtrees managed by an unprivileged process to retain a certain owner
gid, which then enables sharing access to the subtree with another
unprivileged process.

--
v1 -> v2: minor coding style fix (comment)

Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20231208093310.297233-2-max.kellermann@ionos.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-02-23 08:54:51 +01:00
..
2021-08-26 22:28:02 +02:00
2024-02-23 08:54:51 +01:00
2021-12-29 12:28:59 +01:00
2023-09-19 12:22:53 +02:00
2023-02-22 12:57:05 +01:00
2023-09-23 11:10:01 +02:00
2023-12-08 08:48:04 +01:00
2023-08-30 16:18:19 +02:00
2024-01-05 15:13:36 +01:00
2022-12-14 11:37:31 +01:00
2023-01-12 11:58:47 +01:00
2022-07-02 16:41:17 +02:00
2022-07-12 16:35:08 +02:00
2021-12-14 10:57:15 +01:00