1 // SPDX-License-Identifier: BSD-2-Clause
2 /*
3 * Copyright (c) 2023, The ChromiumOS Authors
4 */
5
6 #include <compiler.h>
7 #include <initcall.h>
8 #include <kernel/dt.h>
9 #include <kernel/pseudo_ta.h>
10 #include <kernel/tee_ta_manager.h>
11 #include <kernel/ts_manager.h>
12 #include <kernel/user_ta.h>
13 #include <libfdt.h>
14 #include <pta_widevine.h>
15 #include <stdint.h>
16 #include <string.h>
17 #include <tee_api.h>
18 #include <util.h>
19
20 #define PTA_NAME "widevine.pta"
21
22 #define TPM_AUTH_PUB_MAX_SIZE 1024
23 #define WIDEVINE_PRIV_MAX_SIZE 32
24
25 #define CROS_HWSEC_TA_UUID \
26 { \
27 0xed800e33, 0x3c58, 0x4cae, \
28 { \
29 0xa7, 0xc0, 0xfd, 0x16, 0x0e, 0x35, 0xe0, 0x0d \
30 } \
31 }
32 #define CROS_HDCP_PROV4_TA_UUID \
33 { \
34 0x0feb839c, 0xee25, 0x4920, \
35 { \
36 0x8e, 0xe3, 0xac, 0x8d, 0xaa, 0x86, 0x0d, 0x3b \
37 } \
38 }
39 #define TA_OPTEE_OEMCRYPTO_UUID \
40 { \
41 0xa92d116c, 0xce27, 0x4917, \
42 { \
43 0xb3, 0x0c, 0x4a, 0x41, 0x6e, 0x2d, 0x93, 0x51 \
44 } \
45 }
46
47 static const TEE_UUID allowed_ta_uuids[3] = {
48 CROS_HWSEC_TA_UUID,
49 CROS_HDCP_PROV4_TA_UUID,
50 TA_OPTEE_OEMCRYPTO_UUID,
51 };
52
53 /*
54 * The TPM auth public key. Used to communicate with the TPM from OP-TEE.
55 * The format of data should be TPM2B_PUBLIC.
56 * For more information, please reference the 12.2.5 section:
57 * https://trustedcomputinggroup.org/wp-content/uploads/TCG_TPM2_r1p59_Part2_Structures_pub.pdf
58 */
59 static uint8_t tpm_auth_pub[TPM_AUTH_PUB_MAX_SIZE];
60 static uint32_t tpm_auth_pub_size;
61
62 /*
63 * The Widevine root of trust secret. Used to sign the widevine
64 * requests in OP-TEE. The value is an ECC NIST P-256 scalar.
65 * For more information, please reference the G.1.2 section:
66 * https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-186.pdf
67 */
68 static uint8_t widevine_priv[WIDEVINE_PRIV_MAX_SIZE];
69 static uint32_t widevine_priv_size;
70
init_widevine_dt_data(void)71 static TEE_Result init_widevine_dt_data(void)
72 {
73 int node = 0;
74 int len = 0;
75 void *fdt = NULL;
76 const void *value = NULL;
77
78 fdt = get_secure_dt();
79 if (!fdt)
80 return TEE_ERROR_NO_DATA;
81
82 node = fdt_path_offset(fdt, "/options/op-tee/widevine");
83 if (node < 0)
84 return TEE_ERROR_ITEM_NOT_FOUND;
85
86 value = fdt_getprop(fdt, node, "tcg,tpm-auth-public-key", &len);
87 if (!value)
88 return TEE_ERROR_ITEM_NOT_FOUND;
89
90 if (len > TPM_AUTH_PUB_MAX_SIZE)
91 return TEE_ERROR_OVERFLOW;
92
93 memcpy(tpm_auth_pub, value, len);
94 tpm_auth_pub_size = len;
95
96 value = fdt_getprop(fdt, node, "google,widevine-root-of-trust-ecc-p256",
97 &len);
98 if (!value)
99 return TEE_ERROR_ITEM_NOT_FOUND;
100
101 if (len > WIDEVINE_PRIV_MAX_SIZE)
102 return TEE_ERROR_OVERFLOW;
103
104 memcpy(widevine_priv, value, len);
105 widevine_priv_size = len;
106
107 return TEE_SUCCESS;
108 }
109
110 service_init(init_widevine_dt_data);
111
open_session(uint32_t param_types __unused,TEE_Param params[TEE_NUM_PARAMS]__unused,void ** sess_ctx __unused)112 static TEE_Result open_session(uint32_t param_types __unused,
113 TEE_Param params[TEE_NUM_PARAMS] __unused,
114 void **sess_ctx __unused)
115 {
116 size_t i = 0;
117 struct ts_session *session = ts_get_calling_session();
118
119 /* Make sure we are called from a TA */
120 if (!is_user_ta_ctx(session->ctx))
121 return TEE_ERROR_ACCESS_DENIED;
122
123 /* Make sure we are called from an allowed TA */
124 for (i = 0; i < ARRAY_SIZE(allowed_ta_uuids); i++)
125 if (memcmp(&session->ctx->uuid, &allowed_ta_uuids[i],
126 sizeof(TEE_UUID)) == 0)
127 return TEE_SUCCESS;
128
129 return TEE_ERROR_ACCESS_DENIED;
130 }
131
get_dt_data(uint32_t ptypes,TEE_Param params[TEE_NUM_PARAMS],uint32_t cmd)132 static TEE_Result get_dt_data(uint32_t ptypes, TEE_Param params[TEE_NUM_PARAMS],
133 uint32_t cmd)
134 {
135 uint32_t exp_pt = TEE_PARAM_TYPES(TEE_PARAM_TYPE_MEMREF_OUTPUT,
136 TEE_PARAM_TYPE_NONE,
137 TEE_PARAM_TYPE_NONE,
138 TEE_PARAM_TYPE_NONE);
139 uint8_t *data = NULL;
140 uint32_t data_length = 0;
141
142 if (exp_pt != ptypes)
143 return TEE_ERROR_BAD_PARAMETERS;
144
145 if (cmd == PTA_WIDEVINE_GET_TPM_PUBKEY) {
146 data = tpm_auth_pub;
147 data_length = tpm_auth_pub_size;
148 } else if (cmd == PTA_WIDEVINE_GET_WIDEVINE_PRIVKEY) {
149 data = widevine_priv;
150 data_length = widevine_priv_size;
151 } else {
152 return TEE_ERROR_NOT_IMPLEMENTED;
153 }
154
155 if (data_length == 0)
156 return TEE_ERROR_NO_DATA;
157
158 if (data_length > params[0].memref.size) {
159 params[0].memref.size = data_length;
160 return TEE_ERROR_SHORT_BUFFER;
161 }
162
163 params[0].memref.size = data_length;
164 memcpy(params[0].memref.buffer, data, data_length);
165
166 return TEE_SUCCESS;
167 }
168
169 /*
170 * Trusted Application Entry Points
171 */
invoke_command(void * psess __unused,uint32_t cmd,uint32_t ptypes,TEE_Param params[TEE_NUM_PARAMS])172 static TEE_Result invoke_command(void *psess __unused, uint32_t cmd,
173 uint32_t ptypes,
174 TEE_Param params[TEE_NUM_PARAMS])
175 {
176 return get_dt_data(ptypes, params, cmd);
177 }
178
179 pseudo_ta_register(.uuid = PTA_WIDEVINE_UUID, .name = PTA_NAME,
180 .flags = PTA_DEFAULT_FLAGS,
181 .open_session_entry_point = open_session,
182 .invoke_command_entry_point = invoke_command);
183