Unverified Commit 21cb47be authored by Christian Brauner's avatar Christian Brauner
Browse files

inode: make init and permission helpers idmapped mount aware 

The inode_owner_or_capable() helper determines whether the caller is the
owner of the inode or is capable with respect to that inode. Allow it to
handle idmapped mounts. If the inode is accessed through an idmapped
mount it according to the mount's user namespace. Afterwards the checks
are identical to non-idmapped mounts. If the initial user namespace is
passed nothing changes so non-idmapped mounts will see identical
behavior as before.

Similarly, allow the inode_init_owner() helper to handle idmapped
mounts. It initializes a new inode on idmapped mounts by mapping the
fsuid and fsgid of the caller from the mount's user namespace. If the
initial user namespace is passed nothing changes so non-idmapped mounts
will see identical behavior as before.

Link: https://lore.kernel.org/r/20210121131959.646623-7-christian.brauner@ubuntu.com


Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJames Morris <jamorris@linux.microsoft.com>
Signed-off-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
parent 47291baa

fs/9p/acl.c

+1 −1
Original line number Diff line number Diff line
@@ -258,7 +258,7 @@ static int v9fs_xattr_set_acl(const struct xattr_handler *handler, 


	if (S_ISLNK(inode->i_mode))

		return -EOPNOTSUPP;

	if (!inode_owner_or_capable(inode))

	if (!inode_owner_or_capable(&init_user_ns, inode))

		return -EPERM;

	if (value) {

		/* update the cached acl value */

fs/9p/vfs_inode.c

+1 −1
Original line number Diff line number Diff line
@@ -251,7 +251,7 @@ int v9fs_init_inode(struct v9fs_session_info *v9ses, 
{

	int err = 0;



	inode_init_owner(inode, NULL, mode);

	inode_init_owner(&init_user_ns,inode,  NULL, mode);

	inode->i_blocks = 0;

	inode->i_rdev = rdev;

	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);

fs/attr.c

+3 −3
Original line number Diff line number Diff line
@@ -87,7 +87,7 @@ int setattr_prepare(struct dentry *dentry, struct iattr *attr) 


	/* Make sure a caller can chmod. */

	if (ia_valid & ATTR_MODE) {

		if (!inode_owner_or_capable(inode))

		if (!inode_owner_or_capable(&init_user_ns, inode))

			return -EPERM;

		/* Also check the setgid bit! */

		if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
@@ -98,7 +98,7 @@ int setattr_prepare(struct dentry *dentry, struct iattr *attr) 


	/* Check for setting the inode time. */

	if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) {

		if (!inode_owner_or_capable(inode))

		if (!inode_owner_or_capable(&init_user_ns, inode))

			return -EPERM;

	}
@@ -243,7 +243,7 @@ int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **de 
		if (IS_IMMUTABLE(inode))

			return -EPERM;



		if (!inode_owner_or_capable(inode)) {

		if (!inode_owner_or_capable(&init_user_ns, inode)) {

			error = inode_permission(&init_user_ns, inode,

						 MAY_WRITE);

			if (error)

fs/bfs/dir.c

+1 −1
Original line number Diff line number Diff line
@@ -96,7 +96,7 @@ static int bfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 
	}

	set_bit(ino, info->si_imap);

	info->si_freei--;

	inode_init_owner(inode, dir, mode);

	inode_init_owner(&init_user_ns, inode, dir, mode);

	inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);

	inode->i_blocks = 0;

	inode->i_op = &bfs_file_inops;

fs/btrfs/inode.c

+1 −1
Original line number Diff line number Diff line
@@ -6190,7 +6190,7 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans, 
	if (ret != 0)

		goto fail_unlock;



	inode_init_owner(inode, dir, mode);

	inode_init_owner(&init_user_ns, inode, dir, mode);

	inode_set_bytes(inode, 0);



	inode->i_mtime = current_time(inode);