#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (c) 2017 Google, Inc.  All Rights Reserved.
#
# FS QA Test No. 435
#
# Test that without the encryption key for a directory, long filenames are
# presented in a way which avoids collisions, even though they are abbreviated
# in order to support names up to NAME_MAX bytes.
#
# Regression test for:
#	6332cd32c829 ("f2fs: check entire encrypted bigname when finding a dentry")
#	6b06cdee81d6 ("fscrypt: avoid collisions when presenting long encrypted filenames")
#
# Even with these two fixes it's still possible to create intentional
# collisions.  For now this test covers "accidental" collisions only.
#
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
. ./common/encrypt

# remove previous $seqres.full before test
rm -f $seqres.full

# real QA test starts here
_supported_fs generic
_require_scratch_encryption
_require_command "$KEYCTL_PROG" keyctl

# set up an encrypted directory

_new_session_keyring
_scratch_mkfs_encrypted &>> $seqres.full
_scratch_mount
mkdir $SCRATCH_MNT/edir
keydesc=$(_generate_session_encryption_key)
# -f 0x2: zero-pad to 16-byte boundary (i.e. encryption block boundary)
_set_encpolicy $SCRATCH_MNT/edir $keydesc -f 0x2

# Create files with long names (> 32 bytes, long enough to trigger the use of
# "digested" names) in the encrypted directory.
#
# Use 100,000 files so that we have a good chance of detecting buggy filesystems
# that solely use a 32-bit hash to distinguish files, which f2fs was doing.
#
# Furthermore, make the filenames differ only in the last 16-byte encryption
# block.  This reproduces the bug where it was not accounted for that ciphertext
# stealing (CTS) causes the last two blocks to appear "flipped".
seq -f "$SCRATCH_MNT/edir/abcdefghijklmnopqrstuvwxyz012345%.0f" 100000 | xargs touch
find $SCRATCH_MNT/edir/ -type f | xargs stat -c %i | sort | uniq | wc -l

_unlink_session_encryption_key $keydesc
_scratch_cycle_mount

# Verify that every file has a unique inode number and can be removed without
# error.  With the bug(s), some filenames incorrectly pointed to the same inode,
# and ext4 reported a "Structure needs cleaning" error when removing files.
find $SCRATCH_MNT/edir/ -type f | xargs stat -c %i | sort | uniq | wc -l
rm -rf $SCRATCH_MNT/edir |& head -n 10
stat $SCRATCH_MNT/edir |& _filter_stat |& _filter_scratch

# success, all done
status=0
exit