xfs: fix up non-directory creation in SGID directories

commit 01ea173e103edd5ec41acec65b9261b87e123fc2 upstream.

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 0fa3ecd87848
("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: 1da177e4c3f4 ("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>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 1f61e085676b30bd137798539a93f1a176779093..df1e168b6c0d70ae440a878bc57e6333043272c4 100644 (file)
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -802,6 +802,7 @@ xfs_ialloc(
        xfs_buf_t       **ialloc_context,
        xfs_inode_t     **ipp)
 {
+       struct inode    *dir = pip ? VFS_I(pip) : NULL;
        struct xfs_mount *mp = tp->t_mountp;
        xfs_ino_t       ino;
        xfs_inode_t     *ip;
@@ -847,18 +848,17 @@ xfs_ialloc(
                return error;
        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);
        }
 
        /*