xfstest: overlay: File capabilities should not be lost over copy-up

Make sure file capabilities are not lost over copy-up when file is opened for WRITE but nothing is actually written to it.

Signed-off-by Vivek Goyal <[email protected]>

---
 tests/overlay/064     |   72 ++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/overlay/064.out |    3 ++
 tests/overlay/group   |    1
 3 files changed, 76 insertions(+)

Index: xfstests-dev/tests/overlay/064
===================================================================

tests/overlay/064 2019-01-10 17:06:28.806079686 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +42 -0

@@ -0,0 +1,72 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2018 Red Hat Inc.  All Rights Reserved.
+#
+# FS QA Test 064
+#
+# Make sure CAP_SETUID is not cleared over file copy up.
+#
+# Following commit introduced regression where if a lower file with
+# CAP_SETUID is opened for writing, and capability is cleared over copy up.
+#
+# bd64e57586d3 ("ovl: During copy up, first copy up metadata and then data")
+#
+# A later kernel patch will fix it. This test will help avoid introducing
+# such regressions again.
+#
+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 -f $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+# real QA test starts here
+_supported_fs overlay
+_supported_os Linux
+_require_scratch

Quoted 5 lines · Vivek Goyal

Make sure file capabilities are not lost over copy-up when file is opened for WRITE but nothing is actually written to it.

Signed-off-by Vivek Goyal <[email protected]>

Just some nits...

Quoted 53 lines

---
 tests/overlay/064     |   72 ++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/overlay/064.out |    3 ++
 tests/overlay/group   |    1
 3 files changed, 76 insertions(+)

Index: xfstests-dev/tests/overlay/064
===================================================================

tests/overlay/064 2019-01-10 17:06:28.806079686 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +42 -0

@@ -0,0 +1,72 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2018 Red Hat Inc.  All Rights Reserved.
+#
+# FS QA Test 064
+#
+# Make sure CAP_SETUID is not cleared over file copy up.
+#
+# Following commit introduced regression where if a lower file with
+# CAP_SETUID is opened for writing, and capability is cleared over copy up.
+#
+# bd64e57586d3 ("ovl: During copy up, first copy up metadata and then data")
+#
+# A later kernel patch will fix it. This test will help avoid introducing
+# such regressions again.
+#
+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 -f $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+# real QA test starts here
+_supported_fs overlay
+_supported_os Linux
+_require_scratch

tests/overlay/064 2019-01-10 17:06:28.806079686 -0500 line 52

Quoted 10 lines

tests/overlay/064 2019-01-10 17:06:28.806079686 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +10 -0

+_require_command "$SETCAP_PROG" setcap
+_require_command "$GETCAP_PROG" getcap
+
+# Remove all files from previous tests
+_scratch_mkfs
+
+# Create test file
+lowerdir=${OVL_BASE_SCRATCH_MNT}/${OVL_LOWER}
+upperdir=${OVL_BASE_SCRATCH_MNT}/${OVL_UPPER}
+mkdir -p $lowerdir

Already done by _scratch_mkfs

tests/overlay/064 2019-01-10 17:06:28.806079686 -0500 line 53

Quoted 1 line

tests/overlay/064 2019-01-10 17:06:28.806079686 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +1 -0

+touch ${lowerdir}/file

Not needed.

tests/overlay/064 2019-01-10 17:06:28.806079686 -0500 line 62

Quoted 9 lines

tests/overlay/064 2019-01-10 17:06:28.806079686 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +9 -0

+echo "This is lower" >> ${lowerdir}/file
+# set setuid bit
+$SETCAP_PROG cap_setuid+ep ${lowerdir}/file
+
+_scratch_mount
+
+# Trigger file copy up without actually writing anything to file.
+$XFS_IO_PROG -c "open -a" ${SCRATCH_MNT}/file >>$seqres.full
+

That's wrong syntax and it fails (after opening the file O_RDWR)

The correct syntax is:
$XFS_IO_PROG [-a] -c "quit" ${SCRATCH_MNT}/file >>$seqres.full

Is it important to open O_APPEND? if yes please explain in comment why If not drop -a.

tests/overlay/064 2019-01-10 17:06:28.806079686 -0500 line 69

Quoted 7 lines

tests/overlay/064 2019-01-10 17:06:28.806079686 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +7 -0

+# Make sure cap_setuid is still there
+$GETCAP_PROG ${SCRATCH_MNT}/file | _filter_scratch
+
+# unmount overlayfs
+$UMOUNT_PROG $SCRATCH_MNT
+
+echo "Silence is golden"

You already broke the silence...