core: pta: widevine: Add the init implementation

On the new ChromeOS mediatek platform, we will use the device tree to
pass hardware unique key and the parameters for widevine TAs.

Signed-off-by: Yi Chou <yich@google.com>
Reviewed-by: Joakim Bech <joakim.bech@linaro.org>

core/drivers/sub.mk

@@ -78,6 +78,8 @@ srcs-$(CFG_VERSAL_HUK) += versal_huk.c
 srcs-$(CFG_CBMEM_CONSOLE) += cbmem_console.c
 srcs-$(CFG_RISCV_PLIC) += plic.c
 srcs-$(CFG_HISILICON_CRYPTO_DRIVER) += hisi_trng.c
+srcs-$(CFG_WIDEVINE_HUK) += widevine_huk.c
+
 subdirs-y += crypto
 subdirs-$(CFG_BNXT_FW) += bnxt
 subdirs-$(CFG_DRIVERS_CLK) += clk

core/drivers/widevine_huk.c

@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: BSD-2-Clause
+/*
+ * Copyright (c) 2023, The ChromiumOS Authors
+ */
+
+#include <kernel/tee_common_otp.h>
+#include <libfdt.h>
+#include <stdint.h>
+#include <string.h>
+
+static uint8_t dt_huk[HW_UNIQUE_KEY_LENGTH];
+static bool dt_huk_initialized;
+
+static TEE_Result init_widevine_huk_dt_data(void)
+{
+	int node = 0;
+	int len = 0;
+	void *fdt = NULL;
+	const void *value = NULL;
+
+	if (dt_huk_initialized)
+		return TEE_SUCCESS;
+
+	fdt = get_secure_dt();
+	if (!fdt)
+		return TEE_ERROR_NO_DATA;
+
+	node = fdt_path_offset(fdt, "/options/op-tee/widevine");
+	if (node < 0)
+		return TEE_ERROR_ITEM_NOT_FOUND;
+
+	value = fdt_getprop(fdt, node, "op-tee,hardware-unique-key", &len);
+	if (!value)
+		return TEE_ERROR_ITEM_NOT_FOUND;
+
+	if (len >= HW_UNIQUE_KEY_LENGTH)
+		len = HW_UNIQUE_KEY_LENGTH;
+	else
+		return TEE_ERROR_BAD_FORMAT;
+
+	dt_huk_initialized = true;
+
+	return TEE_SUCCESS;
+}
+
+service_init(init_widevine_huk_dt_data);
+
+TEE_Result tee_otp_get_hw_unique_key(struct tee_hw_unique_key *hwkey)
+{
+	TEE_Result result = TEE_SUCCESS;
+
+	/*
+	 * Ensure we get data from the DT, in case called before service_init()
+	 * handler.
+	 */
+	result = init_widevine_huk_dt_data();
+	if (result != TEE_SUCCESS)
+		return result;
+
+	memcpy(hwkey->data, dt_huk, HW_UNIQUE_KEY_LENGTH);
+
+	return TEE_SUCCESS;
+}

core/pta/sub.mk

@@ -14,6 +14,7 @@ srcs-$(CFG_APDU_PTA) += apdu.c
 srcs-$(CFG_SCMI_PTA) += scmi.c
 srcs-$(CFG_HWRNG_PTA) += hwrng.c
 srcs-$(CFG_RTC_PTA) += rtc.c
+srcs-$(CFG_WIDEVINE_PTA) += widevine.c
 
 subdirs-y += bcm
 subdirs-y += stm32mp

core/pta/widevine.c

@@ -0,0 +1,188 @@
+// SPDX-License-Identifier: BSD-2-Clause
+/*
+ * Copyright (c) 2023, The ChromiumOS Authors
+ */
+
+#include <compiler.h>
+#include <initcall.h>
+#include <kernel/dt.h>
+#include <kernel/pseudo_ta.h>
+#include <kernel/tee_ta_manager.h>
+#include <kernel/ts_manager.h>
+#include <libfdt.h>
+#include <pta_widevine.h>
+#include <stdint.h>
+#include <string.h>
+#include <tee_api.h>
+#include <util.h>
+
+#define PTA_NAME "widevine.pta"
+
+#define TPM_AUTH_PUB_MAX_SIZE 1024
+#define WIDEVINE_PRIV_MAX_SIZE 32
+
+#define CROS_HWSEC_TA_UUID                                             \
+	{                                                              \
+		0xed800e33, 0x3c58, 0x4cae,                            \
+		{                                                      \
+			0xa7, 0xc0, 0xfd, 0x16, 0x0e, 0x35, 0xe0, 0x0d \
+		}                                                      \
+	}
+#define CROS_HDCP_PROV4_TA_UUID                                        \
+	{                                                              \
+		0x0feb839c, 0xee25, 0x4920,                            \
+		{                                                      \
+			0x8e, 0xe3, 0xac, 0x8d, 0xaa, 0x86, 0x0d, 0x3b \
+		}                                                      \
+	}
+#define TA_OPTEE_OEMCRYPTO_UUID                                        \
+	{                                                              \
+		0xa92d116c, 0xce27, 0x4917,                            \
+		{                                                      \
+			0xb3, 0x0c, 0x4a, 0x41, 0x6e, 0x2d, 0x93, 0x51 \
+		}                                                      \
+	}
+
+static const TEE_UUID allowed_ta_uuids[3] = {
+	CROS_HWSEC_TA_UUID,
+	CROS_HDCP_PROV4_TA_UUID,
+	TA_OPTEE_OEMCRYPTO_UUID,
+};
+
+/*
+ * The TPM auth public key. Used to communicate with the TPM from OP-TEE.
+ * The format of data should be TPM2B_PUBLIC.
+ * For more information, please reference the 12.2.5 section:
+ * https://trustedcomputinggroup.org/wp-content/uploads/TCG_TPM2_r1p59_Part2_Structures_pub.pdf
+ */
+static uint8_t tpm_auth_pub[TPM_AUTH_PUB_MAX_SIZE];
+static uint32_t tpm_auth_pub_size;
+
+/*
+ * The Widevine root of trust secret. Used to sign the widevine
+ * requests in OP-TEE. The value is an ECC NIST P-256 scalar.
+ * For more information, please reference the G.1.2 section:
+ * https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-186.pdf
+ */
+static uint8_t widevine_priv[WIDEVINE_PRIV_MAX_SIZE];
+static uint32_t widevine_priv_size;
+
+static TEE_Result init_widevine_dt_data(void)
+{
+	int node = 0;
+	int len = 0;
+	void *fdt = NULL;
+	const void *value = NULL;
+
+	fdt = get_secure_dt();
+	if (!fdt)
+		return TEE_ERROR_NO_DATA;
+
+	node = fdt_path_offset(fdt, "/options/op-tee/widevine");
+	if (node < 0)
+		return TEE_ERROR_ITEM_NOT_FOUND;
+
+	value = fdt_getprop(fdt, node, "tcg,tpm-auth-public-key", &len);
+	if (!value)
+		return TEE_ERROR_ITEM_NOT_FOUND;
+
+	if (len > TPM_AUTH_PUB_MAX_SIZE)
+		return TEE_ERROR_OVERFLOW;
+
+	memcpy(tpm_auth_pub, value, len);
+	tpm_auth_pub_size = len;
+
+	value = fdt_getprop(fdt, node, "google,widevine-root-of-trust-ecc-p256",
+			    &len);
+	if (!value)
+		return TEE_ERROR_ITEM_NOT_FOUND;
+
+	if (len > WIDEVINE_PRIV_MAX_SIZE)
+		return TEE_ERROR_OVERFLOW;
+
+	memcpy(widevine_priv, value, len);
+	widevine_priv_size = len;
+
+	return TEE_SUCCESS;
+}
+
+service_init(init_widevine_dt_data);
+
+static TEE_Result open_session(uint32_t param_types __unused,
+			       TEE_Param params[TEE_NUM_PARAMS] __unused,
+			       void **sess_ctx __unused)
+{
+	size_t i = 0;
+	struct ts_session *session = ts_get_calling_session();
+
+	/* Make sure we are called from a TA */
+	if (to_ta_session(ts_get_current_session())->clnt_id.login !=
+	    TEE_LOGIN_TRUSTED_APP)
+		return TEE_ERROR_ACCESS_DENIED;
+
+	/* Make sure we are called from an allowed TA */
+	for (i = 0; i < ARRAY_SIZE(allowed_ta_uuids); i++)
+		if (memcmp(&session->ctx->uuid, &allowed_ta_uuids[i],
+			   sizeof(TEE_UUID)) == 0)
+			return TEE_SUCCESS;
+
+	return TEE_ERROR_ACCESS_DENIED;
+}
+
+static TEE_Result get_dt_data(uint32_t ptypes, TEE_Param params[TEE_NUM_PARAMS],
+			      uint32_t cmd)
+{
+	uint32_t exp_pt = TEE_PARAM_TYPES(TEE_PARAM_TYPE_MEMREF_OUTPUT,
+					  TEE_PARAM_TYPE_NONE,
+					  TEE_PARAM_TYPE_NONE,
+					  TEE_PARAM_TYPE_NONE);
+	uint8_t *data = NULL;
+	uint32_t data_length = 0;
+
+	if (exp_pt != ptypes)
+		return TEE_ERROR_BAD_PARAMETERS;
+
+	if (cmd == PTA_WIDEVINE_GET_TPM_PUBKEY) {
+		data = tpm_auth_pub;
+		data_length = tpm_auth_pub_size;
+	} else if (cmd == PTA_WIDEVINE_GET_WIDEVINE_PRIVKEY) {
+		data = widevine_priv;
+		data_length = widevine_priv_size;
+	} else {
+		return TEE_ERROR_NOT_IMPLEMENTED;
+	}
+
+	if (data_length == 0)
+		return TEE_ERROR_NO_DATA;
+
+	if (data_length > params[0].memref.size) {
+		params[0].memref.size = data_length;
+		return TEE_ERROR_SHORT_BUFFER;
+	}
+
+	params[0].memref.size = data_length;
+	memcpy(params[0].memref.buffer, data, data_length);
+
+	return TEE_SUCCESS;
+}
+
+/*
+ * Trusted Application Entry Points
+ */
+static TEE_Result invoke_command(void *psess __unused, uint32_t cmd,
+				 uint32_t ptypes,
+				 TEE_Param params[TEE_NUM_PARAMS])
+{
+	switch (cmd) {
+	case PTA_WIDEVINE_GET_TPM_PUBKEY:
+	case PTA_WIDEVINE_GET_WIDEVINE_PRIVKEY:
+		return get_dt_data(ptypes, params, cmd);
+	default:
+		return TEE_ERROR_NOT_IMPLEMENTED;
+	}
+}
+
+pseudo_ta_register(.uuid = PTA_WIDEVINE_UUID, .name = PTA_NAME,
+		   .flags = PTA_DEFAULT_FLAGS,
+		   .open_session_entry_point = open_session,
+		   .invoke_command_entry_point = invoke_command);

lib/libutee/include/pta_widevine.h

@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (c) 2023, The ChromiumOS Authors
+ */
+
+#ifndef __PTA_WIDEVINE_H
+#define __PTA_WIDEVINE_H
+
+/*
+ * Interface to the widevine pseudo-TA, which is used for passing parameters
+ * for widevine TA.
+ */
+#define PTA_WIDEVINE_UUID                                              \
+	{                                                              \
+		0x721f4da9, 0xda05, 0x40d4,                            \
+		{                                                      \
+			0xa1, 0xa3, 0x83, 0x77, 0xc1, 0xe0, 0x8b, 0x0a \
+		}                                                      \
+	}
+
+/*
+ * PTA_WIDEVINE_GET_TPM_PUBKEY - Get Widevine TPM public key
+ * PTA_WIDEVINE_GET_WIDEVINE_PRIVKEY - Get Widevine private key
+ *
+ * [out]     memref[0]        Retrieved key data
+ *
+ * Return codes:
+ * TEE_SUCCESS - Invoke command success
+ * TEE_ERROR_BAD_PARAMETERS - Incorrect parameters
+ * TEE_ERROR_SHORT_BUFFER - Output buffer size is too small
+ * TEE_ERROR_NO_DATA - Requested data not available
+ */
+#define PTA_WIDEVINE_GET_TPM_PUBKEY 0
+#define PTA_WIDEVINE_GET_WIDEVINE_PRIVKEY 1
+
+#endif /* __PTA_WIDEVINE_H */

mk/config.mk

@@ -1129,3 +1129,13 @@ $(eval $(call cfg-depends-all,CFG_CRYPTO_HW_PBKDF2,CFG_CRYPTO_PBKDF2))
 CFG_HALT_CORES_ON_PANIC ?= n
 CFG_HALT_CORES_ON_PANIC_SGI ?= 15
 $(eval $(call cfg-depends-all,CFG_HALT_CORES_ON_PANIC,CFG_GIC))
+
+# When enabled, CFG_WIDEVINE_HUK uses the widevine HUK provided by secure
+# DTB as OP-TEE HUK.
+CFG_WIDEVINE_HUK ?= n
+$(eval $(call cfg-depends-all,CFG_WIDEVINE_HUK,CFG_DT))
+
+# When enabled, CFG_WIDEVINE_PTA embeds a PTA that exposes the keys under
+# DT node "/options/op-tee/widevine" to some specific TAs.
+CFG_WIDEVINE_PTA ?= n
+$(eval $(call cfg-depends-all,CFG_WIDEVINE_PTA,CFG_DT CFG_WIDEVINE_HUK))