qcrypto-luks: extract check and parse header (9fa9c1c2) · Commits · SUMMER2020 / students / proj-2021291

crypto/block-luks.c

+125 −98

Original line number	Diff line number	Diff line
		@@ -500,6 +500,129 @@ qcrypto_block_luks_load_header(QCryptoBlock *block,
		return 0;
		}

		/*
		* Does basic sanity checks on the LUKS header
		*/
		static int
		qcrypto_block_luks_check_header(const QCryptoBlockLUKS luks, Error *errp)
		{
		if (memcmp(luks->header.magic, qcrypto_block_luks_magic,
		QCRYPTO_BLOCK_LUKS_MAGIC_LEN) != 0) {
		error_setg(errp, "Volume is not in LUKS format");
		return -1;
		}

		if (luks->header.version != QCRYPTO_BLOCK_LUKS_VERSION) {
		error_setg(errp, "LUKS version %" PRIu32 " is not supported",
		luks->header.version);
		return -1;
		}
		return 0;
		}

		/*
		* Parses the crypto parameters that are stored in the LUKS header
		*/

		static int
		qcrypto_block_luks_parse_header(QCryptoBlockLUKS luks, Error *errp)
		{
		g_autofree char *cipher_mode = g_strdup(luks->header.cipher_mode);
		char ivgen_name, ivhash_name;
		Error *local_err = NULL;

		/*
		* The cipher_mode header contains a string that we have
		* to further parse, of the format
		*
		* <cipher-mode>-<iv-generator>[:<iv-hash>]
		*
		* eg cbc-essiv:sha256, cbc-plain64
		*/
		ivgen_name = strchr(cipher_mode, '-');
		if (!ivgen_name) {
		error_setg(errp, "Unexpected cipher mode string format %s",
		luks->header.cipher_mode);
		return -1;
		}
		*ivgen_name = '\0';
		ivgen_name++;

		ivhash_name = strchr(ivgen_name, ':');
		if (!ivhash_name) {
		luks->ivgen_hash_alg = 0;
		} else {
		*ivhash_name = '\0';
		ivhash_name++;

		luks->ivgen_hash_alg = qcrypto_block_luks_hash_name_lookup(ivhash_name,
		&local_err);
		if (local_err) {
		error_propagate(errp, local_err);
		return -1;
		}
		}

		luks->cipher_mode = qcrypto_block_luks_cipher_mode_lookup(cipher_mode,
		&local_err);
		if (local_err) {
		error_propagate(errp, local_err);
		return -1;
		}

		luks->cipher_alg =
		qcrypto_block_luks_cipher_name_lookup(luks->header.cipher_name,
		luks->cipher_mode,
		luks->header.master_key_len,
		&local_err);
		if (local_err) {
		error_propagate(errp, local_err);
		return -1;
		}

		luks->hash_alg =
		qcrypto_block_luks_hash_name_lookup(luks->header.hash_spec,
		&local_err);
		if (local_err) {
		error_propagate(errp, local_err);
		return -1;
		}

		luks->ivgen_alg = qcrypto_block_luks_ivgen_name_lookup(ivgen_name,
		&local_err);
		if (local_err) {
		error_propagate(errp, local_err);
		return -1;
		}

		if (luks->ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
		if (!ivhash_name) {
		error_setg(errp, "Missing IV generator hash specification");
		return -1;
		}
		luks->ivgen_cipher_alg =
		qcrypto_block_luks_essiv_cipher(luks->cipher_alg,
		luks->ivgen_hash_alg,
		&local_err);
		if (local_err) {
		error_propagate(errp, local_err);
		return -1;
		}
		} else {

		/*
		* Note we parsed the ivhash_name earlier in the cipher_mode
		* spec string even with plain/plain64 ivgens, but we
		* will ignore it, since it is irrelevant for these ivgens.
		* This is for compat with dm-crypt which will silently
		* ignore hash names with these ivgens rather than report
		* an error about the invalid usage
		*/
		luks->ivgen_cipher_alg = luks->cipher_alg;
		}
		return 0;
		}

		/*
		* Given a key slot, and user password, this will attempt to unlock
		* the master encryption key from the key slot.
		@@ -712,11 +835,8 @@ qcrypto_block_luks_open(QCryptoBlock *block,
		Error **errp)
		{
		QCryptoBlockLUKS *luks = NULL;
		Error *local_err = NULL;
		g_autofree uint8_t *masterkey = NULL;
		char ivgen_name, ivhash_name;
		g_autofree char *password = NULL;
		g_autofree char *cipher_mode = NULL;

		if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
		if (!options->u.luks.key_secret) {
		@@ -738,106 +858,13 @@ qcrypto_block_luks_open(QCryptoBlock *block,
		goto fail;
		}

		if (memcmp(luks->header.magic, qcrypto_block_luks_magic,
		QCRYPTO_BLOCK_LUKS_MAGIC_LEN) != 0) {
		error_setg(errp, "Volume is not in LUKS format");
		goto fail;
		}
		if (luks->header.version != QCRYPTO_BLOCK_LUKS_VERSION) {
		error_setg(errp, "LUKS version %" PRIu32 " is not supported",
		luks->header.version);
		if (qcrypto_block_luks_check_header(luks, errp) < 0) {
		goto fail;
		}

		cipher_mode = g_strdup(luks->header.cipher_mode);

		/*
		* The cipher_mode header contains a string that we have
		* to further parse, of the format
		*
		* <cipher-mode>-<iv-generator>[:<iv-hash>]
		*
		* eg cbc-essiv:sha256, cbc-plain64
		*/
		ivgen_name = strchr(cipher_mode, '-');
		if (!ivgen_name) {
		error_setg(errp, "Unexpected cipher mode string format %s",
		cipher_mode);
		goto fail;
		}
		*ivgen_name = '\0';
		ivgen_name++;

		ivhash_name = strchr(ivgen_name, ':');
		if (!ivhash_name) {
		luks->ivgen_hash_alg = 0;
		} else {
		*ivhash_name = '\0';
		ivhash_name++;

		luks->ivgen_hash_alg = qcrypto_block_luks_hash_name_lookup(ivhash_name,
		&local_err);
		if (local_err) {
		error_propagate(errp, local_err);
		if (qcrypto_block_luks_parse_header(luks, errp) < 0) {
		goto fail;
		}
		}

		luks->cipher_mode = qcrypto_block_luks_cipher_mode_lookup(cipher_mode,
		&local_err);
		if (local_err) {
		error_propagate(errp, local_err);
		goto fail;
		}

		luks->cipher_alg =
		qcrypto_block_luks_cipher_name_lookup(luks->header.cipher_name,
		luks->cipher_mode,
		luks->header.master_key_len,
		&local_err);
		if (local_err) {
		error_propagate(errp, local_err);
		goto fail;
		}

		luks->hash_alg =
		qcrypto_block_luks_hash_name_lookup(luks->header.hash_spec,
		&local_err);
		if (local_err) {
		error_propagate(errp, local_err);
		goto fail;
		}

		luks->ivgen_alg = qcrypto_block_luks_ivgen_name_lookup(ivgen_name,
		&local_err);
		if (local_err) {
		error_propagate(errp, local_err);
		goto fail;
		}

		if (luks->ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
		if (!ivhash_name) {
		error_setg(errp, "Missing IV generator hash specification");
		goto fail;
		}
		luks->ivgen_cipher_alg =
		qcrypto_block_luks_essiv_cipher(luks->cipher_alg,
		luks->ivgen_hash_alg,
		&local_err);
		if (local_err) {
		error_propagate(errp, local_err);
		goto fail;
		}
		} else {
		/* Note we parsed the ivhash_name earlier in the cipher_mode
		* spec string even with plain/plain64 ivgens, but we
		* will ignore it, since it is irrelevant for these ivgens.
		* This is for compat with dm-crypt which will silently
		* ignore hash names with these ivgens rather than report
		* an error about the invalid usage
		*/
		luks->ivgen_cipher_alg = luks->cipher_alg;
		}

		if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
		/* Try to find which key slot our password is valid for