apfstests/common/encrypt

##/bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (c) 2016 Google, Inc.  All Rights Reserved.
#
# Functions for setting up and testing file encryption

#
# _require_scratch_encryption [-c CONTENTS_MODE] [-n FILENAMES_MODE]
#			      [-v POLICY_VERSION]
#
# Require encryption support on the scratch device.
#
# This checks for support for the default type of encryption policy (v1 with
# AES-256-XTS and AES-256-CTS).  Options can be specified to also require
# support for a different type of encryption policy.
#
_require_scratch_encryption()
{
	_require_scratch

	_require_xfs_io_command "set_encpolicy"

	# The 'test_dummy_encryption' mount option interferes with trying to use
	# encryption for real, even if we are just trying to get/set policies
	# and never put any keys in the keyring.  So skip the real encryption
	# tests if the 'test_dummy_encryption' mount option was specified.
	_exclude_scratch_mount_option "test_dummy_encryption"

	# Make a filesystem on the scratch device with the encryption feature
	# enabled.  If this fails then probably the userspace tools (e.g.
	# e2fsprogs or f2fs-tools) are too old to understand encryption.
	if ! _scratch_mkfs_encrypted &>>$seqres.full; then
		_notrun "$FSTYP userspace tools do not support encryption"
	fi

	# Try to mount the filesystem.  If this fails then either the kernel
	# isn't aware of encryption, or the mkfs options were not compatible
	# with encryption (e.g. ext4 with block size != PAGE_SIZE).
	if ! _try_scratch_mount &>>$seqres.full; then
		_notrun "kernel is unaware of $FSTYP encryption feature," \
			"or mkfs options are not compatible with encryption"
	fi

	# The kernel may be aware of encryption without supporting it.  For
	# example, for ext4 this is the case with kernels configured with
	# CONFIG_EXT4_FS_ENCRYPTION=n.  Detect support for encryption by trying
	# to set an encryption policy.  (For ext4 we could instead check for the
	# presence of /sys/fs/ext4/features/encryption, but this is broken on
	# some older kernels and is ext4-specific anyway.)
	mkdir $SCRATCH_MNT/tmpdir
	if _set_encpolicy $SCRATCH_MNT/tmpdir 2>&1 >>$seqres.full | \
		egrep -q 'Inappropriate ioctl for device|Operation not supported'
	then
		_notrun "kernel does not support $FSTYP encryption"
	fi
	rmdir $SCRATCH_MNT/tmpdir

	# If required, check for support for the specific type of encryption
	# policy required by the test.
	if [ $# -ne 0 ]; then
		_require_encryption_policy_support $SCRATCH_MNT "$@"
	fi

	_scratch_unmount
}

_require_encryption_policy_support()
{
	local mnt=$1
	local dir=$mnt/tmpdir
	local set_encpolicy_args=""
	local policy_version=1
	local c

	OPTIND=2
	while getopts "c:n:v:" c; do
		case $c in
		c|n)
			set_encpolicy_args+=" -$c $OPTARG"
			;;
		v)
			set_encpolicy_args+=" -$c $OPTARG"
			policy_version=$OPTARG
			;;
		*)
			_fail "Unrecognized option '$c'"
			;;
		esac
	done
	set_encpolicy_args=${set_encpolicy_args# }

	echo "Checking whether kernel supports encryption policy: $set_encpolicy_args" \
		>> $seqres.full

	mkdir $dir
	if (( policy_version > 1 )); then
		_require_xfs_io_command "get_encpolicy" "-t"
		local output=$(_get_encpolicy $dir -t)
		if [ "$output" != "supported" ]; then
			if [ "$output" = "unsupported" ]; then
				_notrun "kernel does not support $FSTYP encryption v2 API"
			fi
			_fail "Unexpected output from 'get_encpolicy -t': $output"
		fi
		# Both the kernel and xfs_io support v2 encryption policies, and
		# therefore also filesystem-level keys -- since that's the only
		# way to provide keys for v2 policies.
		local raw_key=$(_generate_raw_encryption_key)
		local keyspec=$(_add_enckey $mnt "$raw_key" | awk '{print $NF}')
	else
		_require_command "$KEYCTL_PROG" keyctl
		_new_session_keyring
		local keyspec=$(_generate_session_encryption_key)
	fi
	if _set_encpolicy $dir $keyspec $set_encpolicy_args \
		2>&1 >>$seqres.full | egrep -q 'Invalid argument'; then
		_notrun "kernel does not support encryption policy: '$set_encpolicy_args'"
	fi
	# fscrypt allows setting policies with modes it knows about, even
	# without kernel crypto API support.  E.g. a policy using Adiantum
	# encryption can be set on a kernel without CONFIG_CRYPTO_ADIANTUM.
	# But actually trying to use such an encrypted directory will fail.
	# To reliably check for availability of both the contents and filenames
	# encryption modes, try creating a nonempty file.
	if ! echo foo > $dir/file; then
		_notrun "encryption policy '$set_encpolicy_args' is unusable; probably missing kernel crypto API support"
	fi
	if (( policy_version <= 1 )); then
		$KEYCTL_PROG clear @s
	fi
	rm -r $dir
}

_scratch_mkfs_encrypted()
{
	case $FSTYP in
	ext4|f2fs)
		_scratch_mkfs -O encrypt
		;;
	ubifs)
		# erase the UBI volume; reformated automatically on next mount
		$UBIUPDATEVOL_PROG ${SCRATCH_DEV} -t
		;;
	*)
		_notrun "No encryption support for $FSTYP"
		;;
	esac
}

_scratch_mkfs_sized_encrypted()
{
	case $FSTYP in
	ext4|f2fs)
		MKFS_OPTIONS="$MKFS_OPTIONS -O encrypt" _scratch_mkfs_sized $*
		;;
	*)
		_notrun "Filesystem $FSTYP not supported in _scratch_mkfs_sized_encrypted"
		;;
	esac
}

# Give the invoking shell a new session keyring.  This makes any keys we add to
# the session keyring scoped to the lifetime of the test script.
_new_session_keyring()
{
	$KEYCTL_PROG new_session >>$seqres.full
}

# Generate a key descriptor (16 character hex string)
_generate_key_descriptor()
{
	local keydesc=""
	local i
	for ((i = 0; i < 8; i++)); do
		keydesc="${keydesc}$(printf "%02x" $(( $RANDOM % 256 )))"
	done
	echo $keydesc
}

# Generate a raw encryption key, but don't add it to any keyring yet.
_generate_raw_encryption_key()
{
	local raw=""
	local i
	for ((i = 0; i < 64; i++)); do
		raw="${raw}\\x$(printf "%02x" $(( $RANDOM % 256 )))"
	done
	echo $raw
}

# Add the specified raw encryption key to the session keyring, using the
# specified key descriptor.
_add_session_encryption_key()
{
	local keydesc=$1
	local raw=$2

	#
	# Add the key to the session keyring.  The required structure is:
	#
	#	#define FS_MAX_KEY_SIZE 64
	#	struct fscrypt_key {
	#		u32 mode;
	#		u8 raw[FS_MAX_KEY_SIZE];
	#		u32 size;
	#	} __packed;
	#
	# The kernel ignores 'mode' but requires that 'size' be 64.
	#
	# Keys are named $FSTYP:KEYDESC where KEYDESC is the 16-character key
	# descriptor hex string.  Newer kernels (ext4 4.8 and later, f2fs 4.6
	# and later) also allow the common key prefix "fscrypt:" in addition to
	# their filesystem-specific key prefix ("ext4:", "f2fs:").  It would be
	# nice to use the common key prefix, but for now use the filesystem-
	# specific prefix to make it possible to test older kernels...
	#
	local big_endian=$(echo -ne '\x11' | od -tx2 | head -1 | \
			   cut -f2 -d' ' | cut -c1 )
	if (( big_endian )); then
		local mode='\x00\x00\x00\x00'
		local size='\x00\x00\x00\x40'
	else
		local mode='\x00\x00\x00\x00'
		local size='\x40\x00\x00\x00'
	fi
	echo -n -e "${mode}${raw}${size}" |
		$KEYCTL_PROG padd logon $FSTYP:$keydesc @s >>$seqres.full
}

#
# Generate a random encryption key, add it to the session keyring, and print out
# the resulting key descriptor (example: "8bf798e1a494e1ec").  Requires the
# keyctl program.  It's assumed the caller has already set up a test-scoped
# session keyring using _new_session_keyring.
#
_generate_session_encryption_key()
{
	local keydesc=$(_generate_key_descriptor)
	local raw=$(_generate_raw_encryption_key)

	_add_session_encryption_key $keydesc $raw

	echo $keydesc
}

# Unlink an encryption key from the session keyring, given its key descriptor.
_unlink_session_encryption_key()
{
	local keydesc=$1
	local keyid=$($KEYCTL_PROG search @s logon $FSTYP:$keydesc)
	$KEYCTL_PROG unlink $keyid >>$seqres.full
}

# Revoke an encryption key from the session keyring, given its key descriptor.
_revoke_session_encryption_key()
{
	local keydesc=$1
	local keyid=$($KEYCTL_PROG search @s logon $FSTYP:$keydesc)
	$KEYCTL_PROG revoke $keyid >>$seqres.full
}

# Set an encryption policy on the specified directory.
_set_encpolicy()
{
	local dir=$1
	shift

	$XFS_IO_PROG -c "set_encpolicy $*" "$dir"
}

_user_do_set_encpolicy()
{
	local dir=$1
	shift

	_user_do "$XFS_IO_PROG -c \"set_encpolicy $*\" \"$dir\""
}

# Display the specified file or directory's encryption policy.
_get_encpolicy()
{
	local file=$1
	shift

	$XFS_IO_PROG -c "get_encpolicy $*" "$file"
}

_user_do_get_encpolicy()
{
	local file=$1
	shift

	_user_do "$XFS_IO_PROG -c \"get_encpolicy $*\" \"$file\""
}

# Add an encryption key to the given filesystem.
_add_enckey()
{
	local mnt=$1
	local raw_key=$2
	shift 2

	echo -ne "$raw_key" | $XFS_IO_PROG -c "add_enckey $*" "$mnt"
}

_user_do_add_enckey()
{
	local mnt=$1
	local raw_key=$2
	shift 2

	_user_do "echo -ne \"$raw_key\" | $XFS_IO_PROG -c \"add_enckey $*\" \"$mnt\""
}

# Remove the given encryption key from the given filesystem.
_rm_enckey()
{
	local mnt=$1
	local keyspec=$2
	shift 2

	$XFS_IO_PROG -c "rm_enckey $* $keyspec" "$mnt"
}

_user_do_rm_enckey()
{
	local mnt=$1
	local keyspec=$2
	shift 2

	_user_do "$XFS_IO_PROG -c \"rm_enckey $* $keyspec\" \"$mnt\""
}

# Get the status of the given encryption key on the given filesystem.
_enckey_status()
{
	local mnt=$1
	local keyspec=$2
	shift 2

	$XFS_IO_PROG -c "enckey_status $* $keyspec" "$mnt"
}

_user_do_enckey_status()
{
	local mnt=$1
	local keyspec=$2
	shift 2

	_user_do "$XFS_IO_PROG -c \"enckey_status $* $keyspec\" \"$mnt\""
}

# Retrieve the encryption nonce of the given inode as a hex string.  The nonce
# was randomly generated by the filesystem and isn't exposed directly to
# userspace.  But it can be read using the filesystem's debugging tools.
_get_encryption_nonce()
{
	local device=$1
	local inode=$2

	case $FSTYP in
	ext4)
		# Use debugfs to dump the special xattr named "c", which is the
		# file's fscrypt_context.  This produces a line like:
		#
		#	c (28) = 01 01 04 02 00 00 00 00 00 00 00 00 ef bd 18 76 5d f6 41 4e c0 a2 cd 5f 91 29 7e 12
		#
		# Then filter it to get just the 16-byte 'nonce' field at the end:
		#
		#	efbd18765df6414ec0a2cd5f91297e12
		#
		$DEBUGFS_PROG $device -R "ea_get <$inode> c" 2>>$seqres.full \
			| grep '^c ' | sed 's/^.*=//' | tr -d ' \n' | tail -c 32
		;;
	f2fs)
		# dump.f2fs prints the fscrypt_context like:
		#
		#	xattr: e_name_index:9 e_name:c e_name_len:1 e_value_size:28 e_value:
		#	format: 1
		#	contents_encryption_mode: 0x1
		#	filenames_encryption_mode: 0x4
		#	flags: 0x2
		#	master_key_descriptor: 0000000000000000
		#	nonce: EFBD18765DF6414EC0A2CD5F91297E12
		#
		# Also support the case where the whole xattr is printed as hex,
		# as is the case for fscrypt_context_v2.
		#
		#	xattr: e_name_index:9 e_name:c e_name_len:1 e_value_size:40 e_value:
		#	020104020000000033809BFEBE68A4AD264079B30861DD5E6B9E72D07523C58794ACF52534BAA756
		#
		$DUMP_F2FS_PROG -i $inode $device | awk '
			/\<e_name:c\>/ { found = 1 }
			(/^nonce:/ || /^[[:xdigit:]]+$/) && found {
				print substr($0, length($0) - 31, 32);
				found = 0;
			}'
		;;
	*)
		_fail "_get_encryption_nonce() isn't implemented on $FSTYP"
		;;
	esac
}

# Require support for _get_encryption_nonce()
_require_get_encryption_nonce_support()
{
	echo "Checking for _get_encryption_nonce() support for $FSTYP" >> $seqres.full
	case $FSTYP in
	ext4)
		_require_command "$DEBUGFS_PROG" debugfs
		;;
	f2fs)
		_require_command "$DUMP_F2FS_PROG" dump.f2fs
		# For fscrypt_context_v2, we actually need a f2fs-tools version
		# that has the patch "f2fs-tools: improve xattr value printing"
		# (https://sourceforge.net/p/linux-f2fs/mailman/message/36648640/).
		# Otherwise the xattr is incorrectly parsed as v1.  But just let
		# the test fail in that case, as it was an f2fs-tools bug...
		;;
	*)
		_notrun "_get_encryption_nonce() isn't implemented on $FSTYP"
		;;
	esac
}

# Retrieve the encrypted filename stored on-disk for the given file.
# The name is printed to stdout in binary.
_get_ciphertext_filename()
{
	local device=$1
	local inode=$2
	local dir_inode=$3

	case $FSTYP in
	ext4)
		# Extract the filename from the debugfs output line like:
		#
		#  131075  100644 (1)      0      0       0 22-Apr-2019 16:54 \xa2\x85\xb0z\x13\xe9\x09\x86R\xed\xdc\xce\xad\x14d\x19
		#
		# Bytes are shown either literally or as \xHH-style escape
		# sequences; we have to decode the escaped bytes here.
		#
		$DEBUGFS_PROG $device -R "ls -l -r <$dir_inode>" \
					2>>$seqres.full | perl -ne '
			next if not /^\s*'$inode'\s+/;
			s/.*?\d\d:\d\d //;
			chomp;
			s/\\x([[:xdigit:]]{2})/chr hex $1/eg;
			print;'
		;;
	f2fs)
		# Extract the filename from the dump.f2fs output line like:
		#
		#  i_name                        		[UpkzIPuts9by1oDmE+Ivfw]
		#
		# The name is shown base64-encoded; we have to decode it here.
		#
		$DUMP_F2FS_PROG $device -i $inode | perl -ne '
			next if not /^i_name\s+\[([A-Za-z0-9+,]+)\]/;
			chomp $1;
			my @chars = split //, $1;
			my $ac = 0;
			my $bits = 0;
			my $table = join "", (A..Z, a..z, 0..9, "+", ",");
			foreach (@chars) {
				$ac += index($table, $_) << $bits;
				$bits += 6;
				if ($bits >= 8) {
					print chr($ac & 0xff);
					$ac >>= 8;
					$bits -= 8;
				}
			}
			if ($ac != 0) {
				print STDERR "Invalid base64-encoded string!\n";
			}'
		;;
	*)
		_fail "_get_ciphertext_filename() isn't implemented on $FSTYP"
		;;
	esac
}

# Require support for _get_ciphertext_filename().
_require_get_ciphertext_filename_support()
{
	echo "Checking for _get_ciphertext_filename() support for $FSTYP" >> $seqres.full
	case $FSTYP in
	ext4)
		# Verify that the "ls -l -r" debugfs command is supported and
		# that it hex-encodes non-ASCII characters, rather than using an
		# ambiguous escaping method.  This requires e2fsprogs v1.45.1 or
		# later; or more specifically, a version that has the commit
		# "debugfs: avoid ambiguity when printing filenames".
		_require_command "$DEBUGFS_PROG" debugfs
		_scratch_mount
		touch $SCRATCH_MNT/$'\xc1'
		_scratch_unmount
		if ! $DEBUGFS_PROG $SCRATCH_DEV -R "ls -l -r /" 2>&1 \
			| tee -a $seqres.full | grep -E -q '\s+\\xc1\s*$'; then
			_notrun "debugfs (e2fsprogs) is too old; doesn't support showing unambiguous on-disk filenames"
		fi
		;;
	f2fs)
		# Verify that dump.f2fs shows encrypted filenames in full.  This
		# requires f2fs-tools v1.13.0 or later; or more specifically, a
		# version that has the commit
		# "f2fs-tools: improve filename printing".

		_require_command "$DUMP_F2FS_PROG" dump.f2fs
		_require_command "$KEYCTL_PROG" keyctl
		_scratch_mount
		_new_session_keyring

		local keydesc=$(_generate_session_encryption_key)
		local dir=$SCRATCH_MNT/test.${FUNCNAME[0]}
		local file=$dir/$(perl -e 'print "A" x 255')
		mkdir $dir
		_set_encpolicy $dir $keydesc
		touch $file
		local inode=$(stat -c %i $file)

		_scratch_unmount
		$KEYCTL_PROG clear @s

		# 255-character filename should result in 340 base64 characters.
		if ! $DUMP_F2FS_PROG -i $inode $SCRATCH_DEV \
			| grep -E -q '^i_name[[:space:]]+\[[A-Za-z0-9+,]{340}\]'; then
			_notrun "dump.f2fs (f2fs-tools) is too old; doesn't support showing unambiguous on-disk filenames"
		fi
		;;
	*)
		_notrun "_get_ciphertext_filename() isn't implemented on $FSTYP"
		;;
	esac
}

# Get an encrypted file's list of on-disk blocks as a comma-separated list of
# block offsets from the start of the device.  "Blocks" are 512 bytes each here.
_get_ciphertext_block_list()
{
	local file=$1

	sync
	$XFS_IO_PROG -c fiemap $file | perl -ne '
		next if not /^\s*\d+: \[\d+\.\.\d+\]: (\d+)\.\.(\d+)/;
		print $_ . "," foreach $1..$2;' | sed 's/,$//'
}

# Dump a block list that was previously saved by _get_ciphertext_block_list().
_dump_ciphertext_blocks()
{
	local device=$1
	local blocklist=$2
	local block

	for block in $(tr ',' ' ' <<< $blocklist); do
		dd if=$device bs=512 count=1 skip=$block status=none
	done
}

_do_verify_ciphertext_for_encryption_policy()
{
	local contents_encryption_mode=$1
	local filenames_encryption_mode=$2
	local policy_flags=$3
	local set_encpolicy_args=$4
	local keyspec=$5
	local raw_key_hex=$6
	local crypt_cmd="$here/src/fscrypt-crypt-util $7"

	local blocksize=$(_get_block_size $SCRATCH_MNT)
	local test_contents_files=()
	local test_filenames_files=()
	local i src dir dst inode blocklist \
	      padding_flag padding dir_inode len name f nonce decrypted_name

	# Create files whose encrypted contents we'll verify.  For each, save
	# the information: (copy of original file, inode number of encrypted
	# file, comma-separated block list) into test_contents_files[].
	echo "Creating files for contents verification" >> $seqres.full
	i=1
	rm -f $tmp.testfile_*
	for src in /dev/zero /dev/urandom; do
		head -c $((4 * blocksize)) $src > $tmp.testfile_$i
		(( i++ ))
	done
	dir=$SCRATCH_MNT/encdir
	mkdir $dir
	_set_encpolicy $dir $keyspec $set_encpolicy_args -f $policy_flags
	for src in $tmp.testfile_*; do
		dst=$dir/${src##*.}
		cp $src $dst
		inode=$(stat -c %i $dst)
		blocklist=$(_get_ciphertext_block_list $dst)
		test_contents_files+=("$src $inode $blocklist")
	done

	# Create files whose encrypted names we'll verify.  For each, save the
	# information: (original filename, inode number of encrypted file, inode
	# of parent directory, padding amount) into test_filenames_files[].  Try
	# each padding amount: 4, 8, 16, or 32 bytes.  Also try various filename
	# lengths, including boundary cases.  Assume NAME_MAX == 255.
	echo "Creating files for filenames verification" >> $seqres.full
	for padding_flag in 0 1 2 3; do
		padding=$((4 << padding_flag))
		dir=$SCRATCH_MNT/encdir.pad$padding
		mkdir $dir
		dir_inode=$(stat -c %i $dir)
		_set_encpolicy $dir $keyspec $set_encpolicy_args \
			-f $((policy_flags | padding_flag))
		for len in 1 3 15 16 17 32 100 254 255; do
			name=$(tr -d -C a-zA-Z0-9 < /dev/urandom | head -c $len)
			touch $dir/$name
			inode=$(stat -c %i $dir/$name)
			test_filenames_files+=("$name $inode $dir_inode $padding")
		done
	done

	# Now unmount the filesystem and verify the ciphertext we just wrote.
	_scratch_unmount

	echo "Verifying encrypted file contents" >> $seqres.full
	for f in "${test_contents_files[@]}"; do
		read -r src inode blocklist <<< "$f"
		nonce=$(_get_encryption_nonce $SCRATCH_DEV $inode)
		_dump_ciphertext_blocks $SCRATCH_DEV $blocklist > $tmp.actual_contents
		$crypt_cmd $contents_encryption_mode $raw_key_hex \
			--file-nonce=$nonce --block-size=$blocksize \
			< $src > $tmp.expected_contents
		if ! cmp $tmp.expected_contents $tmp.actual_contents; then
			_fail "Expected encrypted contents != actual encrypted contents.  File: $f"
		fi
		$crypt_cmd $contents_encryption_mode $raw_key_hex --decrypt \
			--file-nonce=$nonce --block-size=$blocksize \
			< $tmp.actual_contents > $tmp.decrypted_contents
		if ! cmp $src $tmp.decrypted_contents; then
			_fail "Contents decryption sanity check failed.  File: $f"
		fi
	done

	echo "Verifying encrypted file names" >> $seqres.full
	for f in "${test_filenames_files[@]}"; do
		read -r name inode dir_inode padding <<< "$f"
		nonce=$(_get_encryption_nonce $SCRATCH_DEV $dir_inode)
		_get_ciphertext_filename $SCRATCH_DEV $inode $dir_inode \
			> $tmp.actual_name
		echo -n "$name" | \
			$crypt_cmd $filenames_encryption_mode $raw_key_hex \
			--file-nonce=$nonce --padding=$padding \
			--block-size=255 > $tmp.expected_name
		if ! cmp $tmp.expected_name $tmp.actual_name; then
			_fail "Expected encrypted filename != actual encrypted filename.  File: $f"
		fi
		$crypt_cmd $filenames_encryption_mode $raw_key_hex --decrypt \
			--file-nonce=$nonce --padding=$padding \
			--block-size=255 < $tmp.actual_name \
			> $tmp.decrypted_name
		decrypted_name=$(tr -d '\0' < $tmp.decrypted_name)
		if [ "$name" != "$decrypted_name" ]; then
			_fail "Filename decryption sanity check failed ($name != $decrypted_name).  File: $f"
		fi
	done
}

_fscrypt_mode_name_to_num()
{
	local name=$1

	case "$name" in
	AES-256-XTS)		echo 1 ;; # FS_ENCRYPTION_MODE_AES_256_XTS
	AES-256-CTS-CBC)	echo 4 ;; # FS_ENCRYPTION_MODE_AES_256_CTS
	AES-128-CBC-ESSIV)	echo 5 ;; # FS_ENCRYPTION_MODE_AES_128_CBC
	AES-128-CTS-CBC)	echo 6 ;; # FS_ENCRYPTION_MODE_AES_128_CTS
	Adiantum)		echo 9 ;; # FS_ENCRYPTION_MODE_ADIANTUM
	*)			_fail "Unknown fscrypt mode: $name" ;;
	esac
}

# Verify that file contents and names are encrypted correctly when an encryption
# policy of the specified type is used.
#
# The first two parameters are the contents and filenames encryption modes to
# test.  Optionally, also specify 'direct' to test the DIRECT_KEY flag, and/or
# 'v2' to test v2 policies.
_verify_ciphertext_for_encryption_policy()
{
	local contents_encryption_mode=$1
	local filenames_encryption_mode=$2
	local opt
	local policy_version=1
	local policy_flags=0
	local set_encpolicy_args=""
	local crypt_util_args=""

	shift 2
	for opt; do
		case "$opt" in
		v2)
			policy_version=2
			;;
		direct)
			if [ $contents_encryption_mode != \
			     $filenames_encryption_mode ]; then
				_fail "For direct key mode, contents and filenames modes must match"
			fi
			(( policy_flags |= 0x04 )) # FS_POLICY_FLAG_DIRECT_KEY
			;;
		*)
			_fail "Unknown option '$opt' passed to ${FUNCNAME[0]}"
			;;
		esac
	done
	local contents_mode_num=$(_fscrypt_mode_name_to_num $contents_encryption_mode)
	local filenames_mode_num=$(_fscrypt_mode_name_to_num $filenames_encryption_mode)

	set_encpolicy_args+=" -c $contents_mode_num"
	set_encpolicy_args+=" -n $filenames_mode_num"

	if (( policy_version > 1 )); then
		set_encpolicy_args+=" -v 2"
		crypt_util_args+=" --kdf=HKDF-SHA512"
		if (( policy_flags & 0x04 )); then
			crypt_util_args+=" --mode-num=$contents_mode_num"
		fi
	else
		if (( policy_flags & 0x04 )); then
			crypt_util_args+=" --kdf=none"
		else
			crypt_util_args+=" --kdf=AES-128-ECB"
		fi
	fi
	set_encpolicy_args=${set_encpolicy_args# }

	_require_scratch_encryption $set_encpolicy_args
	_require_test_program "fscrypt-crypt-util"
	_require_xfs_io_command "fiemap"
	_require_get_encryption_nonce_support
	_require_get_ciphertext_filename_support
	if (( policy_version == 1 )); then
		_require_command "$KEYCTL_PROG" keyctl
	fi

	echo "Creating encryption-capable filesystem" >> $seqres.full
	_scratch_mkfs_encrypted &>> $seqres.full
	_scratch_mount

	echo "Generating encryption key" >> $seqres.full
	local raw_key=$(_generate_raw_encryption_key)
	if (( policy_version > 1 )); then
		local keyspec=$(_add_enckey $SCRATCH_MNT "$raw_key" \
				| awk '{print $NF}')
	else
		local keyspec=$(_generate_key_descriptor)
		_new_session_keyring
		_add_session_encryption_key $keyspec $raw_key
	fi
	local raw_key_hex=$(echo "$raw_key" | tr -d '\\x')

	echo
	echo -e "Verifying ciphertext with parameters:"
	echo -e "\tcontents_encryption_mode: $contents_encryption_mode"
	echo -e "\tfilenames_encryption_mode: $filenames_encryption_mode"
	[ $# -ne 0 ] && echo -e "\toptions: $*"

	_do_verify_ciphertext_for_encryption_policy \
		"$contents_encryption_mode" \
		"$filenames_encryption_mode" \
		"$policy_flags" \
		"$set_encpolicy_args" \
		"$keyspec" \
		"$raw_key_hex" \
		"$crypt_util_args"
}