tests/generic/597

#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (c) 2020 Red Hat, Inc.  All Rights Reserved.
#
# FS QA Test No. 597
#
# Test protected_symlink and protected_hardlink sysctls
#
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()
{
	rm -rf $TEST_DIR/$seq
	[ ! -z "$SYMLINK_PROTECTION" ] \
		&& sysctl -qw fs.protected_symlinks=$SYMLINK_PROTECTION
	[ ! -z "$HARDLINK_PROTECTION" ] \
		&& sysctl -qw fs.protected_hardlinks=$HARDLINK_PROTECTION
	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

# Modify as appropriate.
_supported_fs generic
_require_test
_require_sysctl_variable fs.protected_symlinks
_require_sysctl_variable fs.protected_hardlinks
_require_user fsgqa2
# Do this SECOND so that qa_user is fsgqa, and _user_do uses that account
_require_user fsgqa
_require_symlinks

OWNER=fsgqa2
OTHER=fsgqa

# Save current system state to reset when done
SYMLINK_PROTECTION=`sysctl -n fs.protected_symlinks`
HARDLINK_PROTECTION=`sysctl -n fs.protected_hardlinks`

test_symlink()
{
	ln -s $TEST_DIR/$seq/target $TEST_DIR/$seq/sticky_dir/symlink
	chown $OTHER.$OTHER $TEST_DIR/$seq/sticky_dir
	chown $OWNER.$OWNER $TEST_DIR/$seq/sticky_dir/symlink
	# If we can read the target, we followed the link
	_user_do "cat $TEST_DIR/$seq/sticky_dir/symlink" | _filter_test_dir
	rm -f $TEST_DIR/$seq/sticky_dir/symlink
}

test_hardlink()
{
	chown $OWNER.$OWNER $TEST_DIR/$seq/target
	chmod go-rw $TEST_DIR/$seq/target
	_user_do "ln $TEST_DIR/$seq/target $TEST_DIR/$seq/sticky_dir/hardlink" \
		| _filter_test_dir
	test -f $TEST_DIR/$seq/sticky_dir/hardlink \
		&& echo "successfully created hardlink"
	rm -f $TEST_DIR/$seq/sticky_dir/hardlink
}

setup_tree()
{
	# Create world-writable sticky dir
	mkdir -p $TEST_DIR/$seq/sticky_dir
	chmod 1777 $TEST_DIR/$seq/sticky_dir
	# And a file elsewhere that will be linked to from that sticky dir
	mkdir -p $TEST_DIR/$seq
	# If we can read it, we followed the link.
	echo "successfully followed symlink" > $TEST_DIR/$seq/target
}

setup_tree

# First test fs.protected_symlinks
# With protection on, symlink follows should fail if the
# link owner != the sticky directory owner, and the process
# is not the link owner.
echo "== Test symlink follow protection when"
echo "== process != link owner and dir owner != link owner"
sysctl -w fs.protected_symlinks=0
test_symlink
sysctl -w fs.protected_symlinks=1
test_symlink

echo

# Now test fs.protected_hardlinks
# With protection on, hardlink creation should fail if the
# process does not own the target file, and the process does not have
# read-write access to the target
echo "== Test hardlink create protection when"
echo "== process != target owner and process cannot read target"
sysctl -w fs.protected_hardlinks=0
test_hardlink
sysctl -w fs.protected_hardlinks=1
test_hardlink

# success, all done
status=0
exit