#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (c) 2017 Google, Inc.  All Rights Reserved.
#
# 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").
#
. ./common/preamble
_begin_fstest auto quick encrypt dangerous

# Import common functions.
. ./common/filter
. ./common/encrypt

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

_init_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_session_encryption_key)
_set_encpolicy $dir $keydesc
$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_session_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 no-key
# names on key revocation.  Therefore, the name of the file we're opening here
# may be in either plaintext or no-key form depending on the kernel version, and
# no-key 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