Fix activation of LUKS2 with capi format cipher and kernel crypt name.

While activation of internal cipher algorithms (like aes-generic)
is disallowed, some old LUKS2 images can still use it.

Check the cipher in activate call, but allow to load LUKS2 metadata.
This can allow to add repair code easily and also allow luksDump.

Also fix segfault in reencrypt code for such a header.

Fixes: #820

lib/luks2/luks2_json_metadata.c

@@ -2605,6 +2605,11 @@ int LUKS2_activate(struct crypt_device *cd,
 	if ((r = LUKS2_unmet_requirements(cd, hdr, 0, 0)))
 		return r;
 
+	/* Check that cipher is in compatible format */
+	if (!crypt_get_cipher(cd)) {
+		log_err(cd, _("No known cipher specification pattern detected in LUKS2 header."));
+		return -EINVAL;
+	}
 	r = dm_crypt_target_set(&dmd.segment, 0, dmd.size, crypt_data_device(cd),
 			vk, crypt_get_cipher_spec(cd), crypt_get_iv_offset(cd),
 			crypt_get_data_offset(cd), crypt_get_integrity(cd) ?: "none",

tests/Makefile.am

@@ -68,6 +68,7 @@ EXTRA_DIST = compatimage.img.xz compatv10image.img.xz \
 	luks2_valid_hdr.img.xz \
 	luks2_header_requirements.tar.xz \
 	luks2_mda_images.tar.xz \
+	luks2_invalid_cipher.img.xz \
 	evil_hdr-payload_overwrite.xz \
 	evil_hdr-stripes_payload_dmg.xz \
 	evil_hdr-luks_hdr_damage.xz \
@@ -110,7 +111,8 @@ EXTRA_DIST = compatimage.img.xz compatv10image.img.xz \
 
 CLEANFILES = cryptsetup-tst* valglog* *-fail-*.log test-symbols-list.h fake_token_path.so fake_systemd_tpm_path.so
 clean-local:
-	-rm -rf tcrypt-images luks1-images luks2-images bitlk-images fvault2-images conversion_imgs luks2_valid_hdr.img blkid-luks2-pv-img blkid-luks2-pv-img.bcp external-tokens
+	-rm -rf tcrypt-images luks1-images luks2-images bitlk-images fvault2-images conversion_imgs \
+	luks2_valid_hdr.img blkid-luks2-pv-img blkid-luks2-pv-img.bcp external-tokens luks2_invalid_cipher.img
 
 differ_SOURCES = differ.c
 differ_CFLAGS = $(AM_CFLAGS) -Wall -O2

tests/compat-test2

@@ -16,6 +16,7 @@ IMG10=luks-test-v10
 HEADER_IMG=luks-header
 HEADER_KEYU=luks2_keyslot_unassigned.img
 HEADER_LUKS2_PV=blkid-luks2-pv.img
+HEADER_LUKS2_INV=luks2_invalid_cipher.img
 KEY1=key1
 KEY2=key2
 KEY5=key5
@@ -50,7 +51,9 @@ function remove_mapping()
 	[ -b /dev/mapper/$DEV_NAME2 ] && dmsetup remove --retry $DEV_NAME2
 	[ -b /dev/mapper/$DEV_NAME ] && dmsetup remove --retry $DEV_NAME
 	losetup -d $LOOPDEV >/dev/null 2>&1
-	rm -f $ORIG_IMG $IMG $IMG10 $KEY1 $KEY2 $KEY5 $KEYE $HEADER_IMG $HEADER_KEYU $VK_FILE $HEADER_LUKS2_PV missing-file $TOKEN_FILE0 $TOKEN_FILE1 test_image_* $KEY_FILE0 $KEY_FILE1 >/dev/null 2>&1
+	rm -f $ORIG_IMG $IMG $IMG10 $KEY1 $KEY2 $KEY5 $KEYE $HEADER_IMG $HEADER_KEYU $VK_FILE \
+	$HEADER_LUKS2_PV $HEADER_LUKS2_INV missing-file $TOKEN_FILE0 $TOKEN_FILE1 test_image_* \
+	$KEY_FILE0 $KEY_FILE1 >/dev/null 2>&1
 
 	# unlink whole test keyring
 	[ -n "$TEST_KEYRING" ] && keyctl unlink $TEST_KEYRING "@u" >/dev/null
@@ -1200,5 +1203,17 @@ if [ $HAVE_KEYRING -gt 0 -a -d /proc/sys/kernel/keys ]; then
 	$CRYPTSETUP open -q --test-passphrase --token-only --token-id 0 -q $IMG || fail
 fi
 
+prepare "[44] LUKS2 invalid cipher (kernel cipher driver name)" wipe
+xz -dk $HEADER_LUKS2_INV.xz
+dd if=$HEADER_LUKS2_INV of=$IMG conv=notrunc >/dev/null 2>&1
+$CRYPTSETUP -q luksDump $LOOPDEV | grep -q "capi:xts(ecb(aes-generic))-plain64" || fail
+echo $PWD1 | $CRYPTSETUP open $LOOPDEV --test-passphrase || fail
+echo $PWD1 | $CRYPTSETUP open $LOOPDEV $DEV_NAME 2>&1 | grep -q "No known cipher specification pattern" || fail
+echo $PWD1 | $CRYPTSETUP reencrypt $LOOPDEV >/dev/null 2>&1 && fail
+dmsetup create $DEV_NAME --uuid CRYPT-LUKS2-3d20686f551748cb89911ad32379821b-test --table \
+  "0 8 crypt capi:xts(ecb(aes-generic))-plain64 edaa40709797973715e572bf7d86fcbb9cfe2051083c33c28d58fe4e1e7ff642 0 $LOOPDEV 32768"
+$CRYPTSETUP status $DEV_NAME | grep -q "n/a" || fail
+$CRYPTSETUP close $DEV_NAME ||fail
+
 remove_mapping
 exit 0

tests/meson.build

@@ -21,6 +21,7 @@ test_files_to_copy = [
     'luks2_keyslot_unassigned.img.xz',
     'luks2_mda_images.tar.xz',
     'luks2_valid_hdr.img.xz',
+    'luks2_invalid_cipher.img.xz',
     'tcrypt-images.tar.xz',
     'valid_header_file.xz',
     'xfs_512_block_size.img.xz',