KEYS: asym_tpm: Implement tpm_sign [ver #2] (e73d170f) · Commits · e / devices / android_kernel_fairphone_FP5

crypto/asymmetric_keys/asym_tpm.c

+87 −0

Original line number	Diff line number	Diff line
		@@ -20,9 +20,11 @@
		#define TPM_ORD_FLUSHSPECIFIC 186
		#define TPM_ORD_LOADKEY2 65
		#define TPM_ORD_UNBIND 30
		#define TPM_ORD_SIGN 60
		#define TPM_LOADKEY2_SIZE 59
		#define TPM_FLUSHSPECIFIC_SIZE 18
		#define TPM_UNBIND_SIZE 63
		#define TPM_SIGN_SIZE 63

		#define TPM_RT_KEY 0x00000001

		@@ -189,6 +191,91 @@ static int tpm_unbind(struct tpm_buf *tb,
		return datalen;
		}

		/*
		* Sign a blob provided by userspace (that has had the hash function applied)
		* using a specific key handle. The handle is assumed to have been previously
		* loaded by e.g. LoadKey2.
		*
		* Note that the key signature scheme of the used key should be set to
		* TPM_SS_RSASSAPKCS1v15_DER. This allows the hashed input to be of any size
		* up to key_length_in_bytes - 11 and not be limited to size 20 like the
		* TPM_SS_RSASSAPKCS1v15_SHA1 signature scheme.
		*/
		static int tpm_sign(struct tpm_buf *tb,
		uint32_t keyhandle, unsigned char *keyauth,
		const unsigned char *blob, uint32_t bloblen,
		void *out, uint32_t outlen)
		{
		unsigned char nonceodd[TPM_NONCE_SIZE];
		unsigned char enonce[TPM_NONCE_SIZE];
		unsigned char authdata[SHA1_DIGEST_SIZE];
		uint32_t authhandle = 0;
		unsigned char cont = 0;
		uint32_t ordinal;
		uint32_t datalen;
		int ret;

		ordinal = htonl(TPM_ORD_SIGN);
		datalen = htonl(bloblen);

		/* session for loading the key */
		ret = oiap(tb, &authhandle, enonce);
		if (ret < 0) {
		pr_info("oiap failed (%d)\n", ret);
		return ret;
		}

		/* generate odd nonce */
		ret = tpm_get_random(NULL, nonceodd, TPM_NONCE_SIZE);
		if (ret < 0) {
		pr_info("tpm_get_random failed (%d)\n", ret);
		return ret;
		}

		/* calculate authorization HMAC value */
		ret = TSS_authhmac(authdata, keyauth, SHA1_DIGEST_SIZE, enonce,
		nonceodd, cont, sizeof(uint32_t), &ordinal,
		sizeof(uint32_t), &datalen,
		bloblen, blob, 0, 0);
		if (ret < 0)
		return ret;

		/* build the request buffer */
		INIT_BUF(tb);
		store16(tb, TPM_TAG_RQU_AUTH1_COMMAND);
		store32(tb, TPM_SIGN_SIZE + bloblen);
		store32(tb, TPM_ORD_SIGN);
		store32(tb, keyhandle);
		store32(tb, bloblen);
		storebytes(tb, blob, bloblen);
		store32(tb, authhandle);
		storebytes(tb, nonceodd, TPM_NONCE_SIZE);
		store8(tb, cont);
		storebytes(tb, authdata, SHA1_DIGEST_SIZE);

		ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
		if (ret < 0) {
		pr_info("authhmac failed (%d)\n", ret);
		return ret;
		}

		datalen = LOAD32(tb->data, TPM_DATA_OFFSET);

		ret = TSS_checkhmac1(tb->data, ordinal, nonceodd,
		keyauth, SHA1_DIGEST_SIZE,
		sizeof(uint32_t), TPM_DATA_OFFSET,
		datalen, TPM_DATA_OFFSET + sizeof(uint32_t),
		0, 0);
		if (ret < 0) {
		pr_info("TSS_checkhmac1 failed (%d)\n", ret);
		return ret;
		}

		memcpy(out, tb->data + TPM_DATA_OFFSET + sizeof(uint32_t),
		min(datalen, outlen));

		return datalen;
		}
		/*
		* Maximum buffer size for the BER/DER encoded public key. The public key
		* is of the form SEQUENCE { INTEGER n, INTEGER e } where n is a maximum 2048