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| author | Max Kellermann <max.kellermann@ionos.com> | 2023-12-08 12:33:10 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-02-23 10:42:14 +0300 |
| commit | feaf0752b31077b4fec861fafe3ae581428cbc82 (patch) | |
| tree | 1d8be04061b58c9fb3bc222df203f1e9b7b70688 | |
| parent | 6f921430b07a73c04e6176998a41da03403860f7 (diff) | |
| download | linux-feaf0752b31077b4fec861fafe3ae581428cbc82.tar.xz | |
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>
| -rw-r--r-- | fs/kernfs/dir.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index c91ee05cce74..0ba056e06e48 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -696,6 +696,18 @@ struct kernfs_node *kernfs_new_node(struct kernfs_node *parent, { struct kernfs_node *kn; + if (parent->mode & S_ISGID) { + /* this code block imitates inode_init_owner() for + * kernfs + */ + + if (parent->iattr) + gid = parent->iattr->ia_gid; + + if (flags & KERNFS_DIR) + mode |= S_ISGID; + } + kn = __kernfs_new_node(kernfs_root(parent), parent, name, mode, uid, gid, flags); if (kn) { |