Unverified Commit db998553 authored by Christian Brauner's avatar Christian Brauner
Browse files

fs: introduce two inode i_{u,g}id initialization helpers 

Give filesystem two little helpers that do the right thing when
initializing the i_uid and i_gid fields on idmapped and non-idmapped
mounts. Filesystems shouldn't have to be concerned with too many
details.

Link: https://lore.kernel.org/r/20210320122623.599086-5-christian.brauner@ubuntu.com


Inspired-by: default avatarVivek Goyal <vgoyal@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
parent 8e538913

fs/ext4/ialloc.c

+1 −1
Original line number Diff line number Diff line
@@ -970,7 +970,7 @@ struct inode *__ext4_new_inode(struct user_namespace *mnt_userns, 
		i_gid_write(inode, owner[1]);

	} else if (test_opt(sb, GRPID)) {

		inode->i_mode = mode;

		inode->i_uid = mapped_fsuid(mnt_userns);

		inode_fsuid_set(inode, mnt_userns);

		inode->i_gid = dir->i_gid;

	} else

		inode_init_owner(mnt_userns, inode, dir, mode);

fs/inode.c

+2 −2
Original line number Diff line number Diff line
@@ -2148,7 +2148,7 @@ EXPORT_SYMBOL(init_special_inode); 
void inode_init_owner(struct user_namespace *mnt_userns, struct inode *inode,

		      const struct inode *dir, umode_t mode)

{

	inode->i_uid = mapped_fsuid(mnt_userns);

	inode_fsuid_set(inode, mnt_userns);

	if (dir && dir->i_mode & S_ISGID) {

		inode->i_gid = dir->i_gid;
@@ -2160,7 +2160,7 @@ void inode_init_owner(struct user_namespace *mnt_userns, struct inode *inode, 
			 !capable_wrt_inode_uidgid(mnt_userns, dir, CAP_FSETID))

			mode &= ~S_ISGID;

	} else

		inode->i_gid = mapped_fsgid(mnt_userns);

		inode_fsgid_set(inode, mnt_userns);

	inode->i_mode = mode;

}

EXPORT_SYMBOL(inode_init_owner);

fs/xfs/xfs_inode.c

+1 −1
Original line number Diff line number Diff line
@@ -812,7 +812,7 @@ xfs_init_new_inode( 


	if (dir && !(dir->i_mode & S_ISGID) &&

	    (mp->m_flags & XFS_MOUNT_GRPID)) {

		inode->i_uid = mapped_fsuid(mnt_userns);

		inode_fsuid_set(inode, mnt_userns);

		inode->i_gid = dir->i_gid;

		inode->i_mode = mode;

	} else {

include/linux/fs.h

+28 −0
Original line number Diff line number Diff line
@@ -1692,6 +1692,34 @@ static inline kgid_t mapped_fsgid(struct user_namespace *mnt_userns) 
	return kgid_from_mnt(mnt_userns, current_fsgid());

}



/**

 * inode_fsuid_set - initialize inode's i_uid field with callers fsuid

 * @inode: inode to initialize

 * @mnt_userns: user namespace of the mount the inode was found from

 *

 * Initialize the i_uid field of @inode. If the inode was found/created via

 * an idmapped mount map the caller's fsuid according to @mnt_users.

 */

static inline void inode_fsuid_set(struct inode *inode,

				   struct user_namespace *mnt_userns)

{

	inode->i_uid = mapped_fsuid(mnt_userns);

}



/**

 * inode_fsgid_set - initialize inode's i_gid field with callers fsgid

 * @inode: inode to initialize

 * @mnt_userns: user namespace of the mount the inode was found from

 *

 * Initialize the i_gid field of @inode. If the inode was found/created via

 * an idmapped mount map the caller's fsgid according to @mnt_users.

 */

static inline void inode_fsgid_set(struct inode *inode,

				   struct user_namespace *mnt_userns)

{

	inode->i_gid = mapped_fsgid(mnt_userns);

}



/**

 * fsuidgid_has_mapping() - check whether caller's fsuid/fsgid is mapped

 * @sb: the superblock we want a mapping in