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| author | Christian Brauner <christian.brauner@ubuntu.com> | 2021-07-27 13:48:51 +0300 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2021-08-23 14:19:14 +0300 |
| commit | 5474bf400f16bd1f930627ea65b698bca09dcfc6 (patch) | |
| tree | f74b0732b42d5476e0db43e39b5a56b1bf37b3d9 /fs/btrfs | |
| parent | 3bc71ba02cf5376b390289bef8c9f5d6049f1866 (diff) | |
| download | linux-5474bf400f16bd1f930627ea65b698bca09dcfc6.tar.xz | |
btrfs: check whether fsgid/fsuid are mapped during subvolume creation
When a new subvolume is created btrfs currently doesn't check whether
the fsgid/fsuid of the caller actually have a mapping in the user
namespace attached to the filesystem. The VFS always checks this to make
sure that the caller's fsgid/fsuid can be represented on-disk. This is
most relevant for filesystems that can be mounted inside user namespaces
but it is in general a good hardening measure to prevent unrepresentable
gid/uid from being written to disk.
Since we want to support idmapped mounts for btrfs ioctls to create
subvolumes in follow-up patches this becomes important since we want to
make sure the fsgid/fsuid of the caller as mapped according to the
idmapped mount can be represented on-disk. Simply add the missing
fsuidgid_has_mapping() line from the VFS may_create() version to
btrfs_may_create().
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
| -rw-r--r-- | fs/btrfs/ioctl.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index d09eaa83b5d2..3661d2ce8ef6 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -877,6 +877,8 @@ static inline int btrfs_may_create(struct inode *dir, struct dentry *child) return -EEXIST; if (IS_DEADDIR(dir)) return -ENOENT; + if (!fsuidgid_has_mapping(dir->i_sb, &init_user_ns)) + return -EOVERFLOW; return inode_permission(&init_user_ns, dir, MAY_WRITE | MAY_EXEC); } |