tpm: add AUTH1 cmds for LoadKey2 and GetPubKey

Extend the tpm library with support for single authorized (AUTH1) commands
as specified in the TCG Main Specification 1.2. (The internally used helper
functions are implemented in a way that they could also be used for double
authorized commands if someone needs it.)

Provide enums with the return codes from the TCG Main specification.

For now only a single OIAP session is supported.

OIAP authorized version of the commands TPM_LoadKey2 and TPM_GetPubKey are
provided. Both features are available using the 'tpm' command, too.

Authorized commands are enabled with CONFIG_TPM_AUTH_SESSIONS. (Note that
this also requires CONFIG_SHA1 to be enabled.)

Signed-off-by: Reinhard Pfau <reinhard.pfau@gdsys.cc>
Signed-off-by: Dirk Eibach <dirk.eibach@gdsys.cc>
Acked-by: Che-Liang Chiou <clchiou@chromium.org>
Signed-off-by: Andy Fleming <afleming@freescale.com>

1 files changed, 350 insertions, 1 deletions

diff --git a/lib/tpm.c b/lib/tpm.c
index 42c9bea0f9..f0b4f59eaf 100644
--- a/lib/tpm.c
+++ b/lib/tpm.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2013 The Chromium OS Authors.
+ * Coypright (c) 2013 Guntermann & Drunck GmbH
  *
  * See file CREDITS for list of people who contributed to this
  * project.
@@ -22,6 +23,7 @@
 
 #include <common.h>
 #include <stdarg.h>
+#include <sha1.h>
 #include <tpm.h>
 #include <asm/unaligned.h>
 
@@ -35,8 +37,31 @@ enum {
 	TPM_REQUEST_HEADER_LENGTH	= 10,
 	TPM_RESPONSE_HEADER_LENGTH	= 10,
 	PCR_DIGEST_LENGTH		= 20,
+	DIGEST_LENGTH			= 20,
+	TPM_REQUEST_AUTH_LENGTH		= 45,
+	TPM_RESPONSE_AUTH_LENGTH	= 41,
+	/* some max lengths, valid for RSA keys <= 2048 bits */
+	TPM_KEY12_MAX_LENGTH		= 618,
+	TPM_PUBKEY_MAX_LENGTH		= 288,
 };
 
+#ifdef CONFIG_TPM_AUTH_SESSIONS
+
+#ifndef CONFIG_SHA1
+#error "TPM_AUTH_SESSIONS require SHA1 to be configured, too"
+#endif /* !CONFIG_SHA1 */
+
+struct session_data {
+	int		valid;
+	uint32_t	handle;
+	uint8_t		nonce_even[DIGEST_LENGTH];
+	uint8_t		nonce_odd[DIGEST_LENGTH];
+};
+
+static struct session_data oiap_session = {0, };
+
+#endif /* CONFIG_TPM_AUTH_SESSIONS */
+
 /**
  * Pack data into a byte string.  The data types are specified in
  * the format string: 'b' means unsigned byte, 'w' unsigned word,
@@ -235,7 +260,7 @@ static uint32_t tpm_sendrecv_command(const void *command,
 			response, &response_length);
 	if (err)
 		return TPM_LIB_ERROR;
-	if (response)
+	if (size_ptr)
 		*size_ptr = response_length;
 
 	return tpm_return_code(response);
@@ -579,3 +604,327 @@ uint32_t tpm_get_capability(uint32_t cap_area, uint32_t sub_cap,
 
 	return 0;
 }
+
+#ifdef CONFIG_TPM_AUTH_SESSIONS
+
+/**
+ * Fill an authentication block in a request.
+ * This func can create the first as well as the second auth block (for
+ * double authorized commands).
+ *
+ * @param request	pointer to the request (w/ uninitialised auth data)
+ * @param request_len0	length of the request without auth data
+ * @param handles_len	length of the handles area in request
+ * @param auth_session	pointer to the (valid) auth session to be used
+ * @param request_auth	pointer to the auth block of the request to be filled
+ * @param auth		authentication data (HMAC key)
+ */
+static uint32_t create_request_auth(const void *request, size_t request_len0,
+	size_t handles_len,
+	struct session_data *auth_session,
+	void *request_auth, const void *auth)
+{
+	uint8_t hmac_data[DIGEST_LENGTH * 3 + 1];
+	sha1_context hash_ctx;
+	const size_t command_code_offset = 6;
+	const size_t auth_nonce_odd_offset = 4;
+	const size_t auth_continue_offset = 24;
+	const size_t auth_auth_offset = 25;
+
+	if (!auth_session || !auth_session->valid)
+		return TPM_LIB_ERROR;
+
+	sha1_starts(&hash_ctx);
+	sha1_update(&hash_ctx, request + command_code_offset, 4);
+	if (request_len0 > TPM_REQUEST_HEADER_LENGTH + handles_len)
+		sha1_update(&hash_ctx,
+			    request + TPM_REQUEST_HEADER_LENGTH + handles_len,
+			    request_len0 - TPM_REQUEST_HEADER_LENGTH
+			    - handles_len);
+	sha1_finish(&hash_ctx, hmac_data);
+
+	sha1_starts(&hash_ctx);
+	sha1_update(&hash_ctx, auth_session->nonce_odd, DIGEST_LENGTH);
+	sha1_update(&hash_ctx, hmac_data, sizeof(hmac_data));
+	sha1_finish(&hash_ctx, auth_session->nonce_odd);
+
+	if (pack_byte_string(request_auth, TPM_REQUEST_AUTH_LENGTH, "dsb",
+			     0, auth_session->handle,
+			     auth_nonce_odd_offset, auth_session->nonce_odd,
+			     DIGEST_LENGTH,
+			     auth_continue_offset, 1))
+		return TPM_LIB_ERROR;
+	if (pack_byte_string(hmac_data, sizeof(hmac_data), "ss",
+			     DIGEST_LENGTH,
+			     auth_session->nonce_even,
+			     DIGEST_LENGTH,
+			     2 * DIGEST_LENGTH,
+			     request_auth + auth_nonce_odd_offset,
+			     DIGEST_LENGTH + 1))
+		return TPM_LIB_ERROR;
+	sha1_hmac(auth, DIGEST_LENGTH, hmac_data, sizeof(hmac_data),
+		  request_auth + auth_auth_offset);
+
+	return TPM_SUCCESS;
+}
+
+/**
+ * Verify an authentication block in a response.
+ * Since this func updates the nonce_even in the session data it has to be
+ * called when receiving a succesfull AUTH response.
+ * This func can verify the first as well as the second auth block (for
+ * double authorized commands).
+ *
+ * @param command_code	command code of the request
+ * @param response	pointer to the request (w/ uninitialised auth data)
+ * @param handles_len	length of the handles area in response
+ * @param auth_session	pointer to the (valid) auth session to be used
+ * @param response_auth	pointer to the auth block of the response to be verified
+ * @param auth		authentication data (HMAC key)
+ */
+static uint32_t verify_response_auth(uint32_t command_code,
+	const void *response, size_t response_len0,
+	size_t handles_len,
+	struct session_data *auth_session,
+	const void *response_auth, const void *auth)
+{
+	uint8_t hmac_data[DIGEST_LENGTH * 3 + 1];
+	uint8_t computed_auth[DIGEST_LENGTH];
+	sha1_context hash_ctx;
+	const size_t return_code_offset = 6;
+	const size_t auth_continue_offset = 20;
+	const size_t auth_auth_offset = 21;
+	uint8_t auth_continue;
+
+	if (!auth_session || !auth_session->valid)
+		return TPM_AUTHFAIL;
+	if (pack_byte_string(hmac_data, sizeof(hmac_data), "d",
+			     0, command_code))
+		return TPM_LIB_ERROR;
+	if (response_len0 < TPM_RESPONSE_HEADER_LENGTH)
+		return TPM_LIB_ERROR;
+
+	sha1_starts(&hash_ctx);
+	sha1_update(&hash_ctx, response + return_code_offset, 4);
+	sha1_update(&hash_ctx, hmac_data, 4);
+	if (response_len0 > TPM_RESPONSE_HEADER_LENGTH + handles_len)
+		sha1_update(&hash_ctx,
+			    response + TPM_RESPONSE_HEADER_LENGTH + handles_len,
+			    response_len0 - TPM_RESPONSE_HEADER_LENGTH
+			    - handles_len);
+	sha1_finish(&hash_ctx, hmac_data);
+
+	memcpy(auth_session->nonce_even, response_auth, DIGEST_LENGTH);
+	auth_continue = ((uint8_t *)response_auth)[auth_continue_offset];
+	if (pack_byte_string(hmac_data, sizeof(hmac_data), "ssb",
+			     DIGEST_LENGTH,
+			     response_auth,
+			     DIGEST_LENGTH,
+			     2 * DIGEST_LENGTH,
+			     auth_session->nonce_odd,
+			     DIGEST_LENGTH,
+			     3 * DIGEST_LENGTH,
+			     auth_continue))
+		return TPM_LIB_ERROR;
+
+	sha1_hmac(auth, DIGEST_LENGTH, hmac_data, sizeof(hmac_data),
+		  computed_auth);
+
+	if (memcmp(computed_auth, response_auth + auth_auth_offset,
+		   DIGEST_LENGTH))
+		return TPM_AUTHFAIL;
+
+	return TPM_SUCCESS;
+}
+
+
+uint32_t tpm_terminate_auth_session(uint32_t auth_handle)
+{
+	const uint8_t command[18] = {
+		0x00, 0xc1,		/* TPM_TAG */
+		0x00, 0x00, 0x00, 0x00,	/* parameter size */
+		0x00, 0x00, 0x00, 0xba,	/* TPM_COMMAND_CODE */
+		0x00, 0x00, 0x00, 0x00,	/* TPM_HANDLE */
+		0x00, 0x00, 0x00, 0x02,	/* TPM_RESSOURCE_TYPE */
+	};
+	const size_t req_handle_offset = TPM_REQUEST_HEADER_LENGTH;
+	uint8_t request[COMMAND_BUFFER_SIZE];
+
+	if (pack_byte_string(request, sizeof(request), "sd",
+			     0, command, sizeof(command),
+			     req_handle_offset, auth_handle))
+		return TPM_LIB_ERROR;
+	if (oiap_session.valid && oiap_session.handle == auth_handle)
+		oiap_session.valid = 0;
+
+	return tpm_sendrecv_command(request, NULL, NULL);
+}
+
+uint32_t tpm_end_oiap(void)
+{
+	uint32_t err = TPM_SUCCESS;
+	if (oiap_session.valid)
+		err = tpm_terminate_auth_session(oiap_session.handle);
+	return err;
+}
+
+uint32_t tpm_oiap(uint32_t *auth_handle)
+{
+	const uint8_t command[10] = {
+		0x00, 0xc1,		/* TPM_TAG */
+		0x00, 0x00, 0x00, 0x0a,	/* parameter size */
+		0x00, 0x00, 0x00, 0x0a,	/* TPM_COMMAND_CODE */
+	};
+	const size_t res_auth_handle_offset = TPM_RESPONSE_HEADER_LENGTH;
+	const size_t res_nonce_even_offset = TPM_RESPONSE_HEADER_LENGTH + 4;
+	uint8_t response[COMMAND_BUFFER_SIZE];
+	size_t response_length = sizeof(response);
+	uint32_t err;
+
+	if (oiap_session.valid)
+		tpm_terminate_auth_session(oiap_session.handle);
+
+	err = tpm_sendrecv_command(command, response, &response_length);
+	if (err)
+		return err;
+	if (unpack_byte_string(response, response_length, "ds",
+			       res_auth_handle_offset, &oiap_session.handle,
+			       res_nonce_even_offset, &oiap_session.nonce_even,
+			       (uint32_t)DIGEST_LENGTH))
+		return TPM_LIB_ERROR;
+	oiap_session.valid = 1;
+	if (auth_handle)
+		*auth_handle = oiap_session.handle;
+	return 0;
+}
+
+uint32_t tpm_load_key2_oiap(uint32_t parent_handle,
+		const void *key, size_t key_length,
+		const void *parent_key_usage_auth,
+		uint32_t *key_handle)
+{
+	const uint8_t command[14] = {
+		0x00, 0xc2,		/* TPM_TAG */
+		0x00, 0x00, 0x00, 0x00,	/* parameter size */
+		0x00, 0x00, 0x00, 0x41,	/* TPM_COMMAND_CODE */
+		0x00, 0x00, 0x00, 0x00,	/* parent handle */
+	};
+	const size_t req_size_offset = 2;
+	const size_t req_parent_handle_offset = TPM_REQUEST_HEADER_LENGTH;
+	const size_t req_key_offset = TPM_REQUEST_HEADER_LENGTH + 4;
+	const size_t res_handle_offset = TPM_RESPONSE_HEADER_LENGTH;
+	uint8_t request[sizeof(command) + TPM_KEY12_MAX_LENGTH
+			+ TPM_REQUEST_AUTH_LENGTH];
+	uint8_t response[COMMAND_BUFFER_SIZE];
+	size_t response_length = sizeof(response);
+	uint32_t err;
+
+	if (!oiap_session.valid) {
+		err = tpm_oiap(NULL);
+		if (err)
+			return err;
+	}
+	if (pack_byte_string(request, sizeof(request), "sdds",
+			     0, command, sizeof(command),
+			     req_size_offset,
+			     sizeof(command) + key_length
+			     + TPM_REQUEST_AUTH_LENGTH,
+			     req_parent_handle_offset, parent_handle,
+			     req_key_offset, key, key_length
+		))
+		return TPM_LIB_ERROR;
+
+	err = create_request_auth(request, sizeof(command) + key_length, 4,
+				&oiap_session,
+				request + sizeof(command) + key_length,
+				parent_key_usage_auth);
+	if (err)
+		return err;
+	err = tpm_sendrecv_command(request, response, &response_length);
+	if (err) {
+		if (err == TPM_AUTHFAIL)
+			oiap_session.valid = 0;
+		return err;
+	}
+
+	err = verify_response_auth(0x00000041, response,
+			response_length - TPM_RESPONSE_AUTH_LENGTH,
+			4, &oiap_session,
+			response + response_length - TPM_RESPONSE_AUTH_LENGTH,
+			parent_key_usage_auth);
+	if (err)
+		return err;
+
+	if (key_handle) {
+		if (unpack_byte_string(response, response_length, "d",
+				       res_handle_offset, key_handle))
+			return TPM_LIB_ERROR;
+	}
+
+	return 0;
+}
+
+uint32_t tpm_get_pub_key_oiap(uint32_t key_handle, const void *usage_auth,
+			void *pubkey, size_t *pubkey_len)
+{
+	const uint8_t command[14] = {
+		0x00, 0xc2,		/* TPM_TAG */
+		0x00, 0x00, 0x00, 0x00,	/* parameter size */
+		0x00, 0x00, 0x00, 0x21,	/* TPM_COMMAND_CODE */
+		0x00, 0x00, 0x00, 0x00,	/* key handle */
+	};
+	const size_t req_size_offset = 2;
+	const size_t req_key_handle_offset = TPM_REQUEST_HEADER_LENGTH;
+	const size_t res_pubkey_offset = TPM_RESPONSE_HEADER_LENGTH;
+	uint8_t request[sizeof(command) + TPM_REQUEST_AUTH_LENGTH];
+	uint8_t response[TPM_RESPONSE_HEADER_LENGTH + TPM_PUBKEY_MAX_LENGTH
+			+ TPM_RESPONSE_AUTH_LENGTH];
+	size_t response_length = sizeof(response);
+	uint32_t err;
+
+	if (!oiap_session.valid) {
+		err = tpm_oiap(NULL);
+		if (err)
+			return err;
+	}
+	if (pack_byte_string(request, sizeof(request), "sdd",
+			     0, command, sizeof(command),
+			     req_size_offset,
+			     (uint32_t)(sizeof(command)
+			     + TPM_REQUEST_AUTH_LENGTH),
+			     req_key_handle_offset, key_handle
+		))
+		return TPM_LIB_ERROR;
+	err = create_request_auth(request, sizeof(command), 4, &oiap_session,
+			request + sizeof(command), usage_auth);
+	if (err)
+		return err;
+	err = tpm_sendrecv_command(request, response, &response_length);
+	if (err) {
+		if (err == TPM_AUTHFAIL)
+			oiap_session.valid = 0;
+		return err;
+	}
+	err = verify_response_auth(0x00000021, response,
+			response_length - TPM_RESPONSE_AUTH_LENGTH,
+			0, &oiap_session,
+			response + response_length - TPM_RESPONSE_AUTH_LENGTH,
+			usage_auth);
+	if (err)
+		return err;
+
+	if (pubkey) {
+		if ((response_length - TPM_RESPONSE_HEADER_LENGTH
+			- TPM_RESPONSE_AUTH_LENGTH) > *pubkey_len)
+			return TPM_LIB_ERROR;
+		*pubkey_len = response_length - TPM_RESPONSE_HEADER_LENGTH
+			- TPM_RESPONSE_AUTH_LENGTH;
+		memcpy(pubkey, response + res_pubkey_offset,
+		       response_length - TPM_RESPONSE_HEADER_LENGTH
+		       - TPM_RESPONSE_AUTH_LENGTH);
+	}
+
+	return 0;
+}
+
+#endif /* CONFIG_TPM_AUTH_SESSIONS */