Commit 01ea173e authored Jan 22, 2021 by Christoph Hellwig Committed by Darrick J. Wong Jan 22, 2021

xfs: fix up non-directory creation in SGID directories



XFS always inherits the SGID bit if it is set on the parent inode, while
the generic inode_init_owner does not do this in a few cases where it can
create a possible security problem, see commit 0fa3ecd8
("Fix up non-directory creation in SGID directories") for details.

Switch XFS to use the generic helper for the normal path to fix this,
just keeping the simple field inheritance open coded for the case of the
non-sgid case with the bsdgrpid mount option.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reported-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

parent eaf92540

fs/xfs/xfs_inode.c

+7 −7

Original line number	Diff line number	Diff line
		@@ -775,6 +775,7 @@ xfs_init_new_inode(
		prid_t prid,
		struct xfs_inode **ipp)
		{
		struct inode *dir = pip ? VFS_I(pip) : NULL;
		struct xfs_mount *mp = tp->t_mountp;
		struct xfs_inode *ip;
		unsigned int flags;
		@@ -804,18 +805,17 @@ xfs_init_new_inode(

		ASSERT(ip != NULL);
		inode = VFS_I(ip);
		inode->i_mode = mode;
		set_nlink(inode, nlink);
		inode->i_uid = current_fsuid();
		inode->i_rdev = rdev;
		ip->i_d.di_projid = prid;

		if (pip && XFS_INHERIT_GID(pip)) {
		inode->i_gid = VFS_I(pip)->i_gid;
		if ((VFS_I(pip)->i_mode & S_ISGID) && S_ISDIR(mode))
		inode->i_mode \|= S_ISGID;
		if (dir && !(dir->i_mode & S_ISGID) &&
		(mp->m_flags & XFS_MOUNT_GRPID)) {
		inode->i_uid = current_fsuid();
		inode->i_gid = dir->i_gid;
		inode->i_mode = mode;
		} else {
		inode->i_gid = current_fsgid();
		inode_init_owner(inode, dir, mode);
		}

		/*