1 /*
2 * libjingle
3 * Copyright 2014 Google Inc.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright notice,
9 * this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright notice,
11 * this list of conditions and the following disclaimer in the documentation
12 * and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
17 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
18 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
19 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
22 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
24 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
25 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28 #if defined(HAVE_SRTP) && defined(ENABLE_EXTERNAL_AUTH)
29
30 #include "talk/session/media/externalhmac.h"
31
32 #include <stdlib.h> // For malloc/free.
33
34 extern "C" {
35 #ifdef SRTP_RELATIVE_PATH
36 #include "srtp.h" // NOLINT
37 #include "crypto_kernel.h" // NOLINT
38 #else
39 #include "third_party/libsrtp/srtp/include/srtp.h"
40 #include "third_party/libsrtp/srtp/crypto/include/crypto_kernel.h"
41 #endif // SRTP_RELATIVE_PATH
42 }
43
44 #include "webrtc/base/logging.h"
45
46 // Begin test case 0 */
47 static const uint8_t kExternalHmacTestCase0Key[20] = {
48 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
49 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
50 0x0b, 0x0b, 0x0b, 0x0b
51 };
52
53 static const uint8_t kExternalHmacTestCase0Data[8] = {
54 0x48, 0x69, 0x20, 0x54, 0x68, 0x65, 0x72, 0x65 // "Hi There"
55 };
56
57 static const uint8_t kExternalHmacFakeTag[10] = {
58 0xba, 0xdd, 0xba, 0xdd, 0xba, 0xdd, 0xba, 0xdd, 0xba, 0xdd
59 };
60
61 static const auth_test_case_t kExternalHmacTestCase0 = {
62 20, // Octets in key
63 const_cast<uint8_t*>(kExternalHmacTestCase0Key), // Key
64 8, // Octets in data
65 const_cast<uint8_t*>(kExternalHmacTestCase0Data), // Data
66 10, // Octets in tag
67 const_cast<uint8_t*>(kExternalHmacFakeTag), // Tag
68 NULL // Pointer to next
69 // testcase
70 };
71
72 static const char kExternalHmacDescription[] =
73 "external hmac sha-1 authentication";
74
75 // auth_type_t external_hmac is the hmac metaobject
76
77 static const auth_type_t external_hmac = {
78 external_hmac_alloc,
79 external_hmac_dealloc,
80 (auth_init_func) external_hmac_init,
81 (auth_compute_func) external_hmac_compute,
82 (auth_update_func) external_hmac_update,
83 (auth_start_func) external_hmac_start,
84 const_cast<char*>(kExternalHmacDescription),
85 0, // Instance count.
86 const_cast<auth_test_case_t*>(&kExternalHmacTestCase0),
87 NULL, // No debugging module.
88 EXTERNAL_HMAC_SHA1
89 };
90
91
external_hmac_alloc(auth_t ** a,int key_len,int out_len)92 err_status_t external_hmac_alloc(auth_t** a, int key_len, int out_len) {
93 uint8_t* pointer;
94
95 // Check key length - note that we don't support keys larger
96 // than 20 bytes yet
97 if (key_len > 20)
98 return err_status_bad_param;
99
100 // Check output length - should be less than 20 bytes/
101 if (out_len > 20)
102 return err_status_bad_param;
103
104 // Allocate memory for auth and hmac_ctx_t structures.
105 pointer = new uint8_t[(sizeof(ExternalHmacContext) + sizeof(auth_t))];
106 if (pointer == NULL)
107 return err_status_alloc_fail;
108
109 // Set pointers
110 *a = (auth_t *)pointer;
111 // |external_hmac| is const and libsrtp expects |type| to be non-const.
112 // const conversion is required. |external_hmac| is constant because we don't
113 // want to increase global count in Chrome.
114 (*a)->type = const_cast<auth_type_t*>(&external_hmac);
115 (*a)->state = pointer + sizeof(auth_t);
116 (*a)->out_len = out_len;
117 (*a)->key_len = key_len;
118 (*a)->prefix_len = 0;
119
120 return err_status_ok;
121 }
122
external_hmac_dealloc(auth_t * a)123 err_status_t external_hmac_dealloc(auth_t* a) {
124 // Zeroize entire state
125 memset((uint8_t *)a, 0, sizeof(ExternalHmacContext) + sizeof(auth_t));
126
127 // Free memory
128 delete[] a;
129
130 return err_status_ok;
131 }
132
external_hmac_init(ExternalHmacContext * state,const uint8_t * key,int key_len)133 err_status_t external_hmac_init(ExternalHmacContext* state,
134 const uint8_t* key,
135 int key_len) {
136 if (key_len > HMAC_KEY_LENGTH)
137 return err_status_bad_param;
138
139 memset(state->key, 0, key_len);
140 memcpy(state->key, key, key_len);
141 state->key_length = key_len;
142 return err_status_ok;
143 }
144
external_hmac_start(ExternalHmacContext * state)145 err_status_t external_hmac_start(ExternalHmacContext* state) {
146 return err_status_ok;
147 }
148
external_hmac_update(ExternalHmacContext * state,const uint8_t * message,int msg_octets)149 err_status_t external_hmac_update(ExternalHmacContext* state,
150 const uint8_t* message,
151 int msg_octets) {
152 return err_status_ok;
153 }
154
external_hmac_compute(ExternalHmacContext * state,const void * message,int msg_octets,int tag_len,uint8_t * result)155 err_status_t external_hmac_compute(ExternalHmacContext* state,
156 const void* message,
157 int msg_octets,
158 int tag_len,
159 uint8_t* result) {
160 memcpy(result, kExternalHmacFakeTag, tag_len);
161 return err_status_ok;
162 }
163
external_crypto_init()164 err_status_t external_crypto_init() {
165 // |external_hmac| is const. const_cast is required as libsrtp expects
166 // non-const.
167 err_status_t status = crypto_kernel_replace_auth_type(
168 const_cast<auth_type_t*>(&external_hmac), EXTERNAL_HMAC_SHA1);
169 if (status) {
170 LOG(LS_ERROR) << "Error in replacing default auth module, error: "
171 << status;
172 return err_status_fail;
173 }
174 return err_status_ok;
175 }
176
177 #endif // defined(HAVE_SRTP) && defined(ENABLE_EXTERNAL_AUTH)
178