2 # SPDX-License-Identifier: GPL-2.0
3 # Copyright (c) 2016 Google, Inc. All Rights Reserved.
5 # Functions for setting up and testing file encryption
8 # _require_scratch_encryption [-c CONTENTS_MODE] [-n FILENAMES_MODE]
10 # Require encryption support on the scratch device.
12 # This checks for support for the default type of encryption policy (AES-256-XTS
13 # and AES-256-CTS). Options can be specified to also require support for a
14 # different type of encryption policy.
16 _require_scratch_encryption()
20 _require_xfs_io_command "set_encpolicy"
22 # The 'test_dummy_encryption' mount option interferes with trying to use
23 # encryption for real, even if we are just trying to get/set policies
24 # and never put any keys in the keyring. So skip the real encryption
25 # tests if the 'test_dummy_encryption' mount option was specified.
26 _exclude_scratch_mount_option "test_dummy_encryption"
28 # Make a filesystem on the scratch device with the encryption feature
29 # enabled. If this fails then probably the userspace tools (e.g.
30 # e2fsprogs or f2fs-tools) are too old to understand encryption.
31 if ! _scratch_mkfs_encrypted &>>$seqres.full; then
32 _notrun "$FSTYP userspace tools do not support encryption"
35 # Try to mount the filesystem. If this fails then either the kernel
36 # isn't aware of encryption, or the mkfs options were not compatible
37 # with encryption (e.g. ext4 with block size != PAGE_SIZE).
38 if ! _try_scratch_mount &>>$seqres.full; then
39 _notrun "kernel is unaware of $FSTYP encryption feature," \
40 "or mkfs options are not compatible with encryption"
43 # The kernel may be aware of encryption without supporting it. For
44 # example, for ext4 this is the case with kernels configured with
45 # CONFIG_EXT4_FS_ENCRYPTION=n. Detect support for encryption by trying
46 # to set an encryption policy. (For ext4 we could instead check for the
47 # presence of /sys/fs/ext4/features/encryption, but this is broken on
48 # some older kernels and is ext4-specific anyway.)
49 mkdir $SCRATCH_MNT/tmpdir
50 if _set_encpolicy $SCRATCH_MNT/tmpdir 2>&1 >>$seqres.full | \
51 egrep -q 'Inappropriate ioctl for device|Operation not supported'
53 _notrun "kernel does not support $FSTYP encryption"
55 rmdir $SCRATCH_MNT/tmpdir
57 # If required, check for support for the specific type of encryption
58 # policy required by the test.
60 _require_encryption_policy_support $SCRATCH_MNT "$@"
66 _require_encryption_policy_support()
70 local set_encpolicy_args=""
74 while getopts "c:n:" c; do
77 set_encpolicy_args+=" -$c $OPTARG"
80 _fail "Unrecognized option '$c'"
84 set_encpolicy_args=${set_encpolicy_args# }
86 echo "Checking whether kernel supports encryption policy: $set_encpolicy_args" \
90 _require_command "$KEYCTL_PROG" keyctl
92 local keydesc=$(_generate_session_encryption_key)
93 if _set_encpolicy $dir $keydesc $set_encpolicy_args \
94 2>&1 >>$seqres.full | egrep -q 'Invalid argument'; then
95 _notrun "kernel does not support encryption policy: '$set_encpolicy_args'"
97 # fscrypt allows setting policies with modes it knows about, even
98 # without kernel crypto API support. E.g. a policy using Adiantum
99 # encryption can be set on a kernel without CONFIG_CRYPTO_ADIANTUM.
100 # But actually trying to use such an encrypted directory will fail.
101 # To reliably check for availability of both the contents and filenames
102 # encryption modes, try creating a nonempty file.
103 if ! echo foo > $dir/file; then
104 _notrun "encryption policy '$set_encpolicy_args' is unusable; probably missing kernel crypto API support"
106 $KEYCTL_PROG clear @s
110 _scratch_mkfs_encrypted()
114 _scratch_mkfs -O encrypt
117 # erase the UBI volume; reformated automatically on next mount
118 $UBIUPDATEVOL_PROG ${SCRATCH_DEV} -t
121 _notrun "No encryption support for $FSTYP"
126 _scratch_mkfs_sized_encrypted()
130 MKFS_OPTIONS="$MKFS_OPTIONS -O encrypt" _scratch_mkfs_sized $*
133 _notrun "Filesystem $FSTYP not supported in _scratch_mkfs_sized_encrypted"
138 # Give the invoking shell a new session keyring. This makes any keys we add to
139 # the session keyring scoped to the lifetime of the test script.
140 _new_session_keyring()
142 $KEYCTL_PROG new_session >>$seqres.full
145 # Generate a key descriptor (16 character hex string)
146 _generate_key_descriptor()
150 for ((i = 0; i < 8; i++)); do
151 keydesc="${keydesc}$(printf "%02x" $(( $RANDOM % 256 )))"
156 # Generate a raw encryption key, but don't add it to any keyring yet.
157 _generate_raw_encryption_key()
161 for ((i = 0; i < 64; i++)); do
162 raw="${raw}\\x$(printf "%02x" $(( $RANDOM % 256 )))"
167 # Add the specified raw encryption key to the session keyring, using the
168 # specified key descriptor.
169 _add_session_encryption_key()
175 # Add the key to the session keyring. The required structure is:
177 # #define FS_MAX_KEY_SIZE 64
178 # struct fscrypt_key {
180 # u8 raw[FS_MAX_KEY_SIZE];
184 # The kernel ignores 'mode' but requires that 'size' be 64.
186 # Keys are named $FSTYP:KEYDESC where KEYDESC is the 16-character key
187 # descriptor hex string. Newer kernels (ext4 4.8 and later, f2fs 4.6
188 # and later) also allow the common key prefix "fscrypt:" in addition to
189 # their filesystem-specific key prefix ("ext4:", "f2fs:"). It would be
190 # nice to use the common key prefix, but for now use the filesystem-
191 # specific prefix to make it possible to test older kernels...
193 local big_endian=$(echo -ne '\x11' | od -tx2 | head -1 | \
194 cut -f2 -d' ' | cut -c1 )
195 if (( big_endian )); then
196 local mode='\x00\x00\x00\x00'
197 local size='\x00\x00\x00\x40'
199 local mode='\x00\x00\x00\x00'
200 local size='\x40\x00\x00\x00'
202 echo -n -e "${mode}${raw}${size}" |
203 $KEYCTL_PROG padd logon $FSTYP:$keydesc @s >>$seqres.full
207 # Generate a random encryption key, add it to the session keyring, and print out
208 # the resulting key descriptor (example: "8bf798e1a494e1ec"). Requires the
209 # keyctl program. It's assumed the caller has already set up a test-scoped
210 # session keyring using _new_session_keyring.
212 _generate_session_encryption_key()
214 local keydesc=$(_generate_key_descriptor)
215 local raw=$(_generate_raw_encryption_key)
217 _add_session_encryption_key $keydesc $raw
222 # Unlink an encryption key from the session keyring, given its key descriptor.
223 _unlink_session_encryption_key()
226 local keyid=$($KEYCTL_PROG search @s logon $FSTYP:$keydesc)
227 $KEYCTL_PROG unlink $keyid >>$seqres.full
230 # Revoke an encryption key from the session keyring, given its key descriptor.
231 _revoke_session_encryption_key()
234 local keyid=$($KEYCTL_PROG search @s logon $FSTYP:$keydesc)
235 $KEYCTL_PROG revoke $keyid >>$seqres.full
238 # Set an encryption policy on the specified directory.
244 $XFS_IO_PROG -c "set_encpolicy $*" "$dir"
247 _user_do_set_encpolicy()
252 _user_do "$XFS_IO_PROG -c \"set_encpolicy $*\" \"$dir\""
255 # Display the specified file or directory's encryption policy.
261 $XFS_IO_PROG -c "get_encpolicy $*" "$file"
264 _user_do_get_encpolicy()
269 _user_do "$XFS_IO_PROG -c \"get_encpolicy $*\" \"$file\""
272 # Add an encryption key to the given filesystem.
279 echo -ne "$raw_key" | $XFS_IO_PROG -c "add_enckey $*" "$mnt"
282 _user_do_add_enckey()
288 _user_do "echo -ne \"$raw_key\" | $XFS_IO_PROG -c \"add_enckey $*\" \"$mnt\""
291 # Remove the given encryption key from the given filesystem.
298 $XFS_IO_PROG -c "rm_enckey $* $keyspec" "$mnt"
307 _user_do "$XFS_IO_PROG -c \"rm_enckey $* $keyspec\" \"$mnt\""
310 # Get the status of the given encryption key on the given filesystem.
317 $XFS_IO_PROG -c "enckey_status $* $keyspec" "$mnt"
320 _user_do_enckey_status()
326 _user_do "$XFS_IO_PROG -c \"enckey_status $* $keyspec\" \"$mnt\""
329 # Retrieve the encryption nonce of the given inode as a hex string. The nonce
330 # was randomly generated by the filesystem and isn't exposed directly to
331 # userspace. But it can be read using the filesystem's debugging tools.
332 _get_encryption_nonce()
339 # Use debugfs to dump the special xattr named "c", which is the
340 # file's fscrypt_context. This produces a line like:
342 # 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
344 # Then filter it to get just the 16-byte 'nonce' field at the end:
346 # efbd18765df6414ec0a2cd5f91297e12
348 $DEBUGFS_PROG $device -R "ea_get <$inode> c" 2>>$seqres.full \
349 | grep '^c ' | sed 's/^.*=//' | tr -d ' \n' | tail -c 32
352 # dump.f2fs prints the fscrypt_context like:
354 # xattr: e_name_index:9 e_name:c e_name_len:1 e_value_size:28 e_value:
356 # contents_encryption_mode: 0x1
357 # filenames_encryption_mode: 0x4
359 # master_key_descriptor: 0000000000000000
360 # nonce: EFBD18765DF6414EC0A2CD5F91297E12
361 $DUMP_F2FS_PROG -i $inode $device | awk '
362 /\<e_name:c\>/ { found = 1 }
364 print substr($0, length($0) - 31, 32);
369 _fail "_get_encryption_nonce() isn't implemented on $FSTYP"
374 # Require support for _get_encryption_nonce()
375 _require_get_encryption_nonce_support()
377 echo "Checking for _get_encryption_nonce() support for $FSTYP" >> $seqres.full
380 _require_command "$DEBUGFS_PROG" debugfs
383 _require_command "$DUMP_F2FS_PROG" dump.f2fs
386 _notrun "_get_encryption_nonce() isn't implemented on $FSTYP"
391 # Retrieve the encrypted filename stored on-disk for the given file.
392 # The name is printed to stdout in binary.
393 _get_ciphertext_filename()
401 # Extract the filename from the debugfs output line like:
403 # 131075 100644 (1) 0 0 0 22-Apr-2019 16:54 \xa2\x85\xb0z\x13\xe9\x09\x86R\xed\xdc\xce\xad\x14d\x19
405 # Bytes are shown either literally or as \xHH-style escape
406 # sequences; we have to decode the escaped bytes here.
408 $DEBUGFS_PROG $device -R "ls -l -r <$dir_inode>" \
409 2>>$seqres.full | perl -ne '
410 next if not /^\s*'$inode'\s+/;
413 s/\\x([[:xdigit:]]{2})/chr hex $1/eg;
417 # Extract the filename from the dump.f2fs output line like:
419 # i_name [UpkzIPuts9by1oDmE+Ivfw]
421 # The name is shown base64-encoded; we have to decode it here.
423 $DUMP_F2FS_PROG $device -i $inode | perl -ne '
424 next if not /^i_name\s+\[([A-Za-z0-9+,]+)\]/;
426 my @chars = split //, $1;
429 my $table = join "", (A..Z, a..z, 0..9, "+", ",");
431 $ac += index($table, $_) << $bits;
434 print chr($ac & 0xff);
440 print STDERR "Invalid base64-encoded string!\n";
444 _fail "_get_ciphertext_filename() isn't implemented on $FSTYP"
449 # Require support for _get_ciphertext_filename().
450 _require_get_ciphertext_filename_support()
452 echo "Checking for _get_ciphertext_filename() support for $FSTYP" >> $seqres.full
455 # Verify that the "ls -l -r" debugfs command is supported and
456 # that it hex-encodes non-ASCII characters, rather than using an
457 # ambiguous escaping method. This requires e2fsprogs v1.45.1 or
458 # later; or more specifically, a version that has the commit
459 # "debugfs: avoid ambiguity when printing filenames".
460 _require_command "$DEBUGFS_PROG" debugfs
462 touch $SCRATCH_MNT/$'\xc1'
464 if ! $DEBUGFS_PROG $SCRATCH_DEV -R "ls -l -r /" 2>&1 \
465 | tee -a $seqres.full | grep -E -q '\s+\\xc1\s*$'; then
466 _notrun "debugfs (e2fsprogs) is too old; doesn't support showing unambiguous on-disk filenames"
470 # Verify that dump.f2fs shows encrypted filenames in full. This
471 # requires f2fs-tools v1.13.0 or later; or more specifically, a
472 # version that has the commit
473 # "f2fs-tools: improve filename printing".
475 _require_command "$DUMP_F2FS_PROG" dump.f2fs
476 _require_command "$KEYCTL_PROG" keyctl
480 local keydesc=$(_generate_session_encryption_key)
481 local dir=$SCRATCH_MNT/test.${FUNCNAME[0]}
482 local file=$dir/$(perl -e 'print "A" x 255')
484 _set_encpolicy $dir $keydesc
486 local inode=$(stat -c %i $file)
489 $KEYCTL_PROG clear @s
491 # 255-character filename should result in 340 base64 characters.
492 if ! $DUMP_F2FS_PROG -i $inode $SCRATCH_DEV \
493 | grep -E -q '^i_name[[:space:]]+\[[A-Za-z0-9+,]{340}\]'; then
494 _notrun "dump.f2fs (f2fs-tools) is too old; doesn't support showing unambiguous on-disk filenames"
498 _notrun "_get_ciphertext_filename() isn't implemented on $FSTYP"
503 # Get an encrypted file's list of on-disk blocks as a comma-separated list of
504 # block offsets from the start of the device. "Blocks" are 512 bytes each here.
505 _get_ciphertext_block_list()
510 $XFS_IO_PROG -c fiemap $file | perl -ne '
511 next if not /^\s*\d+: \[\d+\.\.\d+\]: (\d+)\.\.(\d+)/;
512 print $_ . "," foreach $1..$2;' | sed 's/,$//'
515 # Dump a block list that was previously saved by _get_ciphertext_block_list().
516 _dump_ciphertext_blocks()
522 for block in $(tr ',' ' ' <<< $blocklist); do
523 dd if=$device bs=512 count=1 skip=$block status=none
527 _do_verify_ciphertext_for_encryption_policy()
529 local contents_encryption_mode=$1
530 local filenames_encryption_mode=$2
531 local policy_flags=$3
532 local set_encpolicy_args=$4
535 local crypt_cmd="$here/src/fscrypt-crypt-util $7"
537 local blocksize=$(_get_block_size $SCRATCH_MNT)
538 local test_contents_files=()
539 local test_filenames_files=()
540 local i src dir dst inode blocklist \
541 padding_flag padding dir_inode len name f nonce decrypted_name
543 # Create files whose encrypted contents we'll verify. For each, save
544 # the information: (copy of original file, inode number of encrypted
545 # file, comma-separated block list) into test_contents_files[].
546 echo "Creating files for contents verification" >> $seqres.full
548 rm -f $tmp.testfile_*
549 for src in /dev/zero /dev/urandom; do
550 head -c $((4 * blocksize)) $src > $tmp.testfile_$i
553 dir=$SCRATCH_MNT/encdir
555 _set_encpolicy $dir $keydesc $set_encpolicy_args -f $policy_flags
556 for src in $tmp.testfile_*; do
559 inode=$(stat -c %i $dst)
560 blocklist=$(_get_ciphertext_block_list $dst)
561 test_contents_files+=("$src $inode $blocklist")
564 # Create files whose encrypted names we'll verify. For each, save the
565 # information: (original filename, inode number of encrypted file, inode
566 # of parent directory, padding amount) into test_filenames_files[]. Try
567 # each padding amount: 4, 8, 16, or 32 bytes. Also try various filename
568 # lengths, including boundary cases. Assume NAME_MAX == 255.
569 echo "Creating files for filenames verification" >> $seqres.full
570 for padding_flag in 0 1 2 3; do
571 padding=$((4 << padding_flag))
572 dir=$SCRATCH_MNT/encdir.pad$padding
574 dir_inode=$(stat -c %i $dir)
575 _set_encpolicy $dir $keydesc $set_encpolicy_args \
576 -f $((policy_flags | padding_flag))
577 for len in 1 3 15 16 17 32 100 254 255; do
578 name=$(tr -d -C a-zA-Z0-9 < /dev/urandom | head -c $len)
580 inode=$(stat -c %i $dir/$name)
581 test_filenames_files+=("$name $inode $dir_inode $padding")
585 # Now unmount the filesystem and verify the ciphertext we just wrote.
588 echo "Verifying encrypted file contents" >> $seqres.full
589 for f in "${test_contents_files[@]}"; do
590 read -r src inode blocklist <<< "$f"
591 nonce=$(_get_encryption_nonce $SCRATCH_DEV $inode)
592 _dump_ciphertext_blocks $SCRATCH_DEV $blocklist > $tmp.actual_contents
593 $crypt_cmd $contents_encryption_mode $raw_key_hex \
594 --file-nonce=$nonce --block-size=$blocksize \
595 < $src > $tmp.expected_contents
596 if ! cmp $tmp.expected_contents $tmp.actual_contents; then
597 _fail "Expected encrypted contents != actual encrypted contents. File: $f"
599 $crypt_cmd $contents_encryption_mode $raw_key_hex --decrypt \
600 --file-nonce=$nonce --block-size=$blocksize \
601 < $tmp.actual_contents > $tmp.decrypted_contents
602 if ! cmp $src $tmp.decrypted_contents; then
603 _fail "Contents decryption sanity check failed. File: $f"
607 echo "Verifying encrypted file names" >> $seqres.full
608 for f in "${test_filenames_files[@]}"; do
609 read -r name inode dir_inode padding <<< "$f"
610 nonce=$(_get_encryption_nonce $SCRATCH_DEV $dir_inode)
611 _get_ciphertext_filename $SCRATCH_DEV $inode $dir_inode \
614 $crypt_cmd $filenames_encryption_mode $raw_key_hex \
615 --file-nonce=$nonce --padding=$padding \
616 --block-size=255 > $tmp.expected_name
617 if ! cmp $tmp.expected_name $tmp.actual_name; then
618 _fail "Expected encrypted filename != actual encrypted filename. File: $f"
620 $crypt_cmd $filenames_encryption_mode $raw_key_hex --decrypt \
621 --file-nonce=$nonce --padding=$padding \
622 --block-size=255 < $tmp.actual_name \
623 > $tmp.decrypted_name
624 decrypted_name=$(tr -d '\0' < $tmp.decrypted_name)
625 if [ "$name" != "$decrypted_name" ]; then
626 _fail "Filename decryption sanity check failed ($name != $decrypted_name). File: $f"
631 _fscrypt_mode_name_to_num()
636 AES-256-XTS) echo 1 ;; # FS_ENCRYPTION_MODE_AES_256_XTS
637 AES-256-CTS-CBC) echo 4 ;; # FS_ENCRYPTION_MODE_AES_256_CTS
638 AES-128-CBC-ESSIV) echo 5 ;; # FS_ENCRYPTION_MODE_AES_128_CBC
639 AES-128-CTS-CBC) echo 6 ;; # FS_ENCRYPTION_MODE_AES_128_CTS
640 Adiantum) echo 9 ;; # FS_ENCRYPTION_MODE_ADIANTUM
641 *) _fail "Unknown fscrypt mode: $name" ;;
645 # Verify that file contents and names are encrypted correctly when an encryption
646 # policy of the specified type is used.
648 # The first two parameters are the contents and filenames encryption modes to
649 # test. Optionally, also specify 'direct' to test the DIRECT_KEY flag.
650 _verify_ciphertext_for_encryption_policy()
652 local contents_encryption_mode=$1
653 local filenames_encryption_mode=$2
656 local set_encpolicy_args=""
657 local crypt_util_args=""
663 if [ $contents_encryption_mode != \
664 $filenames_encryption_mode ]; then
665 _fail "For direct key mode, contents and filenames modes must match"
667 (( policy_flags |= 0x04 )) # FS_POLICY_FLAG_DIRECT_KEY
670 _fail "Unknown option '$opt' passed to ${FUNCNAME[0]}"
674 local contents_mode_num=$(_fscrypt_mode_name_to_num $contents_encryption_mode)
675 local filenames_mode_num=$(_fscrypt_mode_name_to_num $filenames_encryption_mode)
677 set_encpolicy_args+=" -c $contents_mode_num"
678 set_encpolicy_args+=" -n $filenames_mode_num"
680 if (( policy_flags & 0x04 )); then
681 crypt_util_args+=" --kdf=none"
683 crypt_util_args+=" --kdf=AES-128-ECB"
685 set_encpolicy_args=${set_encpolicy_args# }
687 _require_scratch_encryption $set_encpolicy_args
688 _require_test_program "fscrypt-crypt-util"
689 _require_xfs_io_command "fiemap"
690 _require_get_encryption_nonce_support
691 _require_get_ciphertext_filename_support
692 _require_command "$KEYCTL_PROG" keyctl
694 echo "Creating encryption-capable filesystem" >> $seqres.full
695 _scratch_mkfs_encrypted &>> $seqres.full
698 echo "Generating encryption key" >> $seqres.full
699 local raw_key=$(_generate_raw_encryption_key)
700 local keydesc=$(_generate_key_descriptor)
702 _add_session_encryption_key $keydesc $raw_key
703 local raw_key_hex=$(echo "$raw_key" | tr -d '\\x')
706 echo -e "Verifying ciphertext with parameters:"
707 echo -e "\tcontents_encryption_mode: $contents_encryption_mode"
708 echo -e "\tfilenames_encryption_mode: $filenames_encryption_mode"
709 [ $# -ne 0 ] && echo -e "\toptions: $*"
711 _do_verify_ciphertext_for_encryption_policy \
712 "$contents_encryption_mode" \
713 "$filenames_encryption_mode" \
715 "$set_encpolicy_args" \