apfstests/tests/generic/421

#! /bin/bash
# FS QA Test generic/421
#
# Test revoking an encryption key during concurrent I/O.  Regression test for
# 1b53cf9815bb ("fscrypt: remove broken support for detecting keyring key
# revocation").
#
#-----------------------------------------------------------------------
# Copyright (c) 2017 Google, Inc.  All Rights Reserved.
#
# Author: Eric Biggers <ebiggers@google.com>
#
# 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 -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
_supported_os Linux
_require_scratch_encryption
_require_xfs_io_command "set_encpolicy"
_require_command "$KEYCTL_PROG" keyctl

_new_session_keyring
_scratch_mkfs_encrypted &>> $seqres.full
_scratch_mount

dir=$SCRATCH_MNT/encrypted_dir
file=$dir/file

# 4 processes, 2 MB per process
nproc=4
slice=2

# Create an encrypted file and sync its data to disk.
rm -rf $dir
mkdir $dir
keydesc=$(_generate_encryption_key)
$XFS_IO_PROG -c "set_encpolicy $keydesc" $dir
$XFS_IO_PROG -f $file -c "pwrite 0 $((nproc*slice))M" -c "fsync" > /dev/null

# Create processes to read from the encrypted file.  Use fadvise to wipe the
# pagecache before each read, ensuring that each read actually does decryption.
for ((proc = 0; proc < nproc; proc++)); do
	(
		range="$((proc * slice))M ${slice}M"
		while [ ! -e $tmp.done ]; do
			$XFS_IO_PROG $file -c "fadvise -d $range" \
					   -c "pread $range" &> /dev/null
		done
	) &
done

# Wait a second for the readers to start up.
sleep 1

# Revoke the encryption key.
keyid=$(_revoke_encryption_key $keydesc)

# Now try to open the file again.  In buggy kernels this caused concurrent
# readers to crash with a NULL pointer dereference during decryption.
#
# Note that the fix also made filenames stop "immediately" reverting to their
# ciphertext on key revocation.  Therefore, the name of the file we're opening
# here may be in either plaintext or ciphertext depending on the kernel version,
# and ciphertext names are unpredictable anyway, so just use 'find' to find it.
cat $(find $dir -type f) > /dev/null

# Wait for readers to exit
touch $tmp.done
wait

# success, all done
echo "Didn't crash!"
status=0
exit