xfs: Regression test for vulnerable directory integrity check

If a malicious XFS contains a block+ format directory wherein the
directory inode's core.mode is corrupted, and there are
subdirectories of the corrupted directory, an attempt to traverse up
the directory tree by running xfs_scrub will crash the kernel in
__xfs_dir3_data_check.

Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

tests/xfs/448

@@ -0,0 +1,96 @@
+#! /bin/bash
+# FS QA Test No. 448
+#
+# Regression test for commit:
+# 46c59736d809 ("xfs: harden directory integrity checks some more")
+#
+# If a malicious XFS contains a block+ format directory wherein
+# the directory inode's core.mode is corrupted, and there are
+# subdirectories of the corrupted directory, an attempt to traverse
+# up the directory tree by running xfs_scrub will crash the
+# kernel in __xfs_dir3_data_check.
+#
+# Notice:
+# we should have non fatal asserts configured, because assert
+# failures triggered by the intentional corrupt would crash system.
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2018 FUJITSU LIMITED. All Rights Reserved.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it would be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write the Free Software Foundation,
+# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#-----------------------------------------------------------------------
+
+seq=`basename "$0"`
+seqres="$RESULT_DIR/$seq"
+echo "QA output created by $seq"
+
+here=`pwd`
+tmp=/tmp/$$
+status=1    # failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+	cd /
+	rm -rf $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+. ./common/populate
+
+# real QA test starts here
+_supported_os Linux
+_supported_fs xfs
+_require_scratch_nocheck
+_require_xfs_io_command "scrub"
+# Corrupt XFS on purpose, and skip if assert failures would crash system.
+_require_no_xfs_bug_on_assert
+
+rm -f "$seqres.full"
+
+# Format and mount
+_scratch_mkfs | _filter_mkfs > $seqres.full 2> $tmp.mkfs || _fail "mkfs failed"
+_scratch_mount
+
+# Get directory block size
+. $tmp.mkfs
+
+# Create a block+(e.g. leaf) format directory
+__populate_create_dir "${SCRATCH_MNT}/dir_leaf" "$((dirbsize / 12))"
+
+# Get the block+ directory inode and a subdirectory inode of it
+subdino=$(stat -c "%i" "$(find ${SCRATCH_MNT}/dir_leaf/* -type d | head -1)")
+dino=$(stat -c "%i" "${SCRATCH_MNT}/dir_leaf")
+
+# Get the subdirectory's generation number
+_scratch_unmount
+subdgen=$(_scratch_xfs_get_metadata_field "core.gen" "inode $subdino")
+
+# Corrupt the directory inode's core.mode
+setmode="0100755"
+_scratch_xfs_set_metadata_field "core.mode" "$setmode" "inode $dino" >> $seqres.full
+getmode=$(_scratch_xfs_get_metadata_field "core.mode" "inode $dino")
+[ "$getmode" != "$setmode" ] && _fail "failed to set core.mode"
+
+# Scrub parent directory in subdirectory (online)
+_scratch_mount
+$XFS_IO_PROG -x -c "scrub parent $subdino $subdgen" ${SCRATCH_MNT} >> $seqres.full
+
+echo "Silence is golden"
+
+# success, all done
+status=0
+exit

tests/xfs/448.out

@@ -0,0 +1,2 @@
+QA output created by 448
+Silence is golden

tests/xfs/group

@@ -445,3 +445,4 @@
 445 auto quick filestreams
 446 auto quick
 447 auto mount
+448 auto quick fuzzers