1 /******************************************************************************
2 *
3 * Copyright 1999-2012 Broadcom Corporation
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at:
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 ******************************************************************************/
18
19 /******************************************************************************
20 *
21 * this file contains GATT authentication handling functions
22 *
23 ******************************************************************************/
24 #include "bt_target.h"
25 #include "bt_utils.h"
26
27 #include <string.h>
28 #include "bt_common.h"
29
30 #include "btm_int.h"
31 #include "gatt_api.h"
32 #include "gatt_int.h"
33 #include "osi/include/osi.h"
34
35 using base::StringPrintf;
36
37 /*******************************************************************************
38 *
39 * Function gatt_sign_data
40 *
41 * Description This function sign the data for write command.
42 *
43 * Returns true if encrypted, otherwise false.
44 *
45 ******************************************************************************/
gatt_sign_data(tGATT_CLCB * p_clcb)46 static bool gatt_sign_data(tGATT_CLCB* p_clcb) {
47 tGATT_VALUE* p_attr = (tGATT_VALUE*)p_clcb->p_attr_buf;
48 uint8_t *p_data = NULL, *p;
49 uint16_t payload_size = p_clcb->p_tcb->payload_size;
50 bool status = false;
51 uint8_t* p_signature;
52
53 /* do not need to mark channel securoty activity for data signing */
54 gatt_set_sec_act(p_clcb->p_tcb, GATT_SEC_OK);
55
56 p_data =
57 (uint8_t*)osi_malloc(p_attr->len + 3); /* 3 = 2 byte handle + opcode */
58
59 p = p_data;
60 UINT8_TO_STREAM(p, GATT_SIGN_CMD_WRITE);
61 UINT16_TO_STREAM(p, p_attr->handle);
62 ARRAY_TO_STREAM(p, p_attr->value, p_attr->len);
63
64 /* sign data length should be attribulte value length plus 2B handle + 1B op
65 * code */
66 if ((payload_size - GATT_AUTH_SIGN_LEN - 3) < p_attr->len)
67 p_attr->len = payload_size - GATT_AUTH_SIGN_LEN - 3;
68
69 p_signature = p_attr->value + p_attr->len;
70 if (BTM_BleDataSignature(
71 p_clcb->p_tcb->peer_bda, p_data,
72 (uint16_t)(p_attr->len + 3), /* 3 = 2 byte handle + opcode */
73 p_signature)) {
74 p_attr->len += BTM_BLE_AUTH_SIGN_LEN;
75 gatt_set_ch_state(p_clcb->p_tcb, GATT_CH_OPEN);
76 gatt_act_write(p_clcb, GATT_SEC_SIGN_DATA);
77 } else {
78 gatt_end_operation(p_clcb, GATT_INTERNAL_ERROR, NULL);
79 }
80
81 osi_free(p_data);
82
83 return status;
84 }
85
86 /*******************************************************************************
87 *
88 * Function gatt_verify_signature
89 *
90 * Description This function start to verify the sign data when receiving
91 * the data from peer device.
92 *
93 * Returns
94 *
95 ******************************************************************************/
gatt_verify_signature(tGATT_TCB & tcb,BT_HDR * p_buf)96 void gatt_verify_signature(tGATT_TCB& tcb, BT_HDR* p_buf) {
97 uint16_t cmd_len;
98 uint8_t op_code;
99 uint8_t *p, *p_orig = (uint8_t*)(p_buf + 1) + p_buf->offset;
100 uint32_t counter;
101
102 if (p_buf->len < GATT_AUTH_SIGN_LEN + 4) {
103 LOG(ERROR) << StringPrintf("%s: Data length %u less than expected %u",
104 __func__, p_buf->len, GATT_AUTH_SIGN_LEN + 4);
105 return;
106 }
107 cmd_len = p_buf->len - GATT_AUTH_SIGN_LEN + 4;
108 p = p_orig + cmd_len - 4;
109 STREAM_TO_UINT32(counter, p);
110
111 if (!BTM_BleVerifySignature(tcb.peer_bda, p_orig, cmd_len, counter, p)) {
112 /* if this is a bad signature, assume from attacker, ignore it */
113 LOG(ERROR) << StringPrintf("Signature Verification Failed, data ignored");
114 return;
115 }
116
117 STREAM_TO_UINT8(op_code, p_orig);
118 gatt_server_handle_client_req(tcb, op_code, (uint16_t)(p_buf->len - 1),
119 p_orig);
120 }
121 /*******************************************************************************
122 *
123 * Function gatt_sec_check_complete
124 *
125 * Description security check complete and proceed to data sending action.
126 *
127 * Returns void.
128 *
129 ******************************************************************************/
gatt_sec_check_complete(bool sec_check_ok,tGATT_CLCB * p_clcb,uint8_t sec_act)130 void gatt_sec_check_complete(bool sec_check_ok, tGATT_CLCB* p_clcb,
131 uint8_t sec_act) {
132 if (p_clcb && p_clcb->p_tcb && p_clcb->p_tcb->pending_enc_clcb.empty()) {
133 gatt_set_sec_act(p_clcb->p_tcb, GATT_SEC_NONE);
134 }
135
136 if (!sec_check_ok) {
137 gatt_end_operation(p_clcb, GATT_AUTH_FAIL, NULL);
138 } else if (p_clcb->operation == GATTC_OPTYPE_WRITE) {
139 gatt_act_write(p_clcb, sec_act);
140 } else if (p_clcb->operation == GATTC_OPTYPE_READ) {
141 gatt_act_read(p_clcb, p_clcb->counter);
142 }
143 }
144 /*******************************************************************************
145 *
146 * Function gatt_enc_cmpl_cback
147 *
148 * Description link encryption complete callback.
149 *
150 * Returns
151 *
152 ******************************************************************************/
gatt_enc_cmpl_cback(const RawAddress * bd_addr,tBT_TRANSPORT transport,UNUSED_ATTR void * p_ref_data,tBTM_STATUS result)153 void gatt_enc_cmpl_cback(const RawAddress* bd_addr, tBT_TRANSPORT transport,
154 UNUSED_ATTR void* p_ref_data, tBTM_STATUS result) {
155 VLOG(1) << StringPrintf("gatt_enc_cmpl_cback");
156 tGATT_TCB* p_tcb = gatt_find_tcb_by_addr(*bd_addr, transport);
157 if (!p_tcb) {
158 LOG(ERROR) << StringPrintf("%s: enc callback for unknown bd_addr",
159 __func__);
160 return;
161 }
162
163 if (gatt_get_sec_act(p_tcb) == GATT_SEC_ENC_PENDING) return;
164
165 if (p_tcb->pending_enc_clcb.empty()) {
166 LOG(ERROR) << StringPrintf("%s: no operation waiting for encrypting",
167 __func__);
168 return;
169 }
170
171 tGATT_CLCB* p_clcb = p_tcb->pending_enc_clcb.front();
172 p_tcb->pending_enc_clcb.pop();
173
174 bool status = false;
175 if (result == BTM_SUCCESS) {
176 if (gatt_get_sec_act(p_tcb) == GATT_SEC_ENCRYPT_MITM) {
177 uint8_t sec_flag = 0;
178 BTM_GetSecurityFlagsByTransport(*bd_addr, &sec_flag, transport);
179
180 if (sec_flag & BTM_SEC_FLAG_LKEY_AUTHED) {
181 status = true;
182 }
183 } else {
184 status = true;
185 }
186 }
187
188 gatt_sec_check_complete(status, p_clcb, p_tcb->sec_act);
189
190 /* start all other pending operation in queue */
191 std::queue<tGATT_CLCB*> new_pending_clcbs;
192 while (!p_tcb->pending_enc_clcb.empty()) {
193 tGATT_CLCB* p_clcb = p_tcb->pending_enc_clcb.front();
194 p_tcb->pending_enc_clcb.pop();
195 if (gatt_security_check_start(p_clcb)) new_pending_clcbs.push(p_clcb);
196 }
197 p_tcb->pending_enc_clcb = new_pending_clcbs;
198 }
199
200 /*******************************************************************************
201 *
202 * Function gatt_notify_enc_cmpl
203 *
204 * Description link encryption complete notification for all encryption
205 * process initiated outside GATT.
206 *
207 * Returns
208 *
209 ******************************************************************************/
gatt_notify_enc_cmpl(const RawAddress & bd_addr)210 void gatt_notify_enc_cmpl(const RawAddress& bd_addr) {
211 tGATT_TCB* p_tcb = gatt_find_tcb_by_addr(bd_addr, BT_TRANSPORT_LE);
212 if (!p_tcb) {
213 VLOG(1) << StringPrintf(
214 "notify GATT for encryption completion of unknown device");
215 return;
216 }
217
218 for (uint8_t i = 0; i < GATT_MAX_APPS; i++) {
219 if (gatt_cb.cl_rcb[i].in_use && gatt_cb.cl_rcb[i].app_cb.p_enc_cmpl_cb) {
220 (*gatt_cb.cl_rcb[i].app_cb.p_enc_cmpl_cb)(gatt_cb.cl_rcb[i].gatt_if,
221 bd_addr);
222 }
223 }
224
225 if (gatt_get_sec_act(p_tcb) == GATT_SEC_ENC_PENDING) {
226 gatt_set_sec_act(p_tcb, GATT_SEC_NONE);
227
228 std::queue<tGATT_CLCB*> new_pending_clcbs;
229 while (!p_tcb->pending_enc_clcb.empty()) {
230 tGATT_CLCB* p_clcb = p_tcb->pending_enc_clcb.front();
231 p_tcb->pending_enc_clcb.pop();
232 if (gatt_security_check_start(p_clcb)) new_pending_clcbs.push(p_clcb);
233 }
234 p_tcb->pending_enc_clcb = new_pending_clcbs;
235 }
236 }
237 /*******************************************************************************
238 *
239 * Function gatt_set_sec_act
240 *
241 * Description This function set the sec_act in clcb
242 *
243 * Returns none
244 *
245 ******************************************************************************/
gatt_set_sec_act(tGATT_TCB * p_tcb,tGATT_SEC_ACTION sec_act)246 void gatt_set_sec_act(tGATT_TCB* p_tcb, tGATT_SEC_ACTION sec_act) {
247 if (p_tcb) {
248 p_tcb->sec_act = sec_act;
249 }
250 }
251 /*******************************************************************************
252 *
253 * Function gatt_get_sec_act
254 *
255 * Description This function get the sec_act in clcb
256 *
257 * Returns none
258 *
259 ******************************************************************************/
gatt_get_sec_act(tGATT_TCB * p_tcb)260 tGATT_SEC_ACTION gatt_get_sec_act(tGATT_TCB* p_tcb) {
261 tGATT_SEC_ACTION sec_act = GATT_SEC_NONE;
262 if (p_tcb) {
263 sec_act = p_tcb->sec_act;
264 }
265 return sec_act;
266 }
267 /**
268 * This routine determine the security action based on auth_request and current
269 * link status. Returns tGATT_SEC_ACTION (security action)
270 */
gatt_determine_sec_act(tGATT_CLCB * p_clcb)271 tGATT_SEC_ACTION gatt_determine_sec_act(tGATT_CLCB* p_clcb) {
272 tGATT_SEC_ACTION act = GATT_SEC_OK;
273 uint8_t sec_flag;
274 tGATT_TCB* p_tcb = p_clcb->p_tcb;
275 tGATT_AUTH_REQ auth_req = p_clcb->auth_req;
276 bool is_link_encrypted = false;
277 bool is_link_key_known = false;
278 bool is_key_mitm = false;
279 uint8_t key_type;
280 tBTM_BLE_SEC_REQ_ACT sec_act = BTM_LE_SEC_NONE;
281
282 if (auth_req == GATT_AUTH_REQ_NONE) return act;
283
284 BTM_GetSecurityFlagsByTransport(p_tcb->peer_bda, &sec_flag,
285 p_clcb->p_tcb->transport);
286
287 btm_ble_link_sec_check(p_tcb->peer_bda, auth_req, &sec_act);
288
289 /* if a encryption is pending, need to wait */
290 if (sec_act == BTM_BLE_SEC_REQ_ACT_DISCARD && auth_req != GATT_AUTH_REQ_NONE)
291 return GATT_SEC_ENC_PENDING;
292
293 if (sec_flag & (BTM_SEC_FLAG_ENCRYPTED | BTM_SEC_FLAG_LKEY_KNOWN)) {
294 if (sec_flag & BTM_SEC_FLAG_ENCRYPTED) is_link_encrypted = true;
295
296 is_link_key_known = true;
297
298 if (sec_flag & BTM_SEC_FLAG_LKEY_AUTHED) is_key_mitm = true;
299 }
300
301 /* first check link key upgrade required or not */
302 switch (auth_req) {
303 case GATT_AUTH_REQ_MITM:
304 case GATT_AUTH_REQ_SIGNED_MITM:
305 if (!is_key_mitm) act = GATT_SEC_ENCRYPT_MITM;
306 break;
307
308 case GATT_AUTH_REQ_NO_MITM:
309 case GATT_AUTH_REQ_SIGNED_NO_MITM:
310 if (!is_link_key_known) act = GATT_SEC_ENCRYPT_NO_MITM;
311 break;
312 default:
313 break;
314 }
315
316 /* now check link needs to be encrypted or not if the link key upgrade is not
317 * required */
318 if (act == GATT_SEC_OK) {
319 if (p_tcb->transport == BT_TRANSPORT_LE &&
320 (p_clcb->operation == GATTC_OPTYPE_WRITE) &&
321 (p_clcb->op_subtype == GATT_WRITE_NO_RSP)) {
322 /* this is a write command request
323 check data signing required or not */
324 if (!is_link_encrypted) {
325 btm_ble_get_enc_key_type(p_tcb->peer_bda, &key_type);
326
327 if ((key_type & BTM_LE_KEY_LCSRK) &&
328 ((auth_req == GATT_AUTH_REQ_SIGNED_NO_MITM) ||
329 (auth_req == GATT_AUTH_REQ_SIGNED_MITM))) {
330 act = GATT_SEC_SIGN_DATA;
331 } else {
332 act = GATT_SEC_ENCRYPT;
333 }
334 }
335 } else {
336 if (!is_link_encrypted) {
337 act = GATT_SEC_ENCRYPT;
338 }
339 }
340 }
341
342 return act;
343 }
344
345 /*******************************************************************************
346 *
347 * Function gatt_get_link_encrypt_status
348 *
349 * Description This routine get the encryption status of the specified link
350 *
351 *
352 * Returns tGATT_STATUS link encryption status
353 *
354 ******************************************************************************/
gatt_get_link_encrypt_status(tGATT_TCB & tcb)355 tGATT_STATUS gatt_get_link_encrypt_status(tGATT_TCB& tcb) {
356 tGATT_STATUS encrypt_status = GATT_NOT_ENCRYPTED;
357 uint8_t sec_flag = 0;
358
359 BTM_GetSecurityFlagsByTransport(tcb.peer_bda, &sec_flag, tcb.transport);
360
361 if ((sec_flag & BTM_SEC_FLAG_ENCRYPTED) &&
362 (sec_flag & BTM_SEC_FLAG_LKEY_KNOWN)) {
363 encrypt_status = GATT_ENCRYPED_NO_MITM;
364 if (sec_flag & BTM_SEC_FLAG_LKEY_AUTHED)
365 encrypt_status = GATT_ENCRYPED_MITM;
366 }
367
368 VLOG(1) << StringPrintf("gatt_get_link_encrypt_status status=0x%x",
369 encrypt_status);
370 return encrypt_status;
371 }
372
373 /*******************************************************************************
374 *
375 * Function gatt_convert_sec_action
376 *
377 * Description Convert GATT security action enum into equivalent
378 * BTM BLE security action enum
379 *
380 * Returns bool true - conversation is successful
381 *
382 ******************************************************************************/
gatt_convert_sec_action(tGATT_SEC_ACTION gatt_sec_act,tBTM_BLE_SEC_ACT * p_btm_sec_act)383 static bool gatt_convert_sec_action(tGATT_SEC_ACTION gatt_sec_act,
384 tBTM_BLE_SEC_ACT* p_btm_sec_act) {
385 bool status = true;
386 switch (gatt_sec_act) {
387 case GATT_SEC_ENCRYPT:
388 *p_btm_sec_act = BTM_BLE_SEC_ENCRYPT;
389 break;
390 case GATT_SEC_ENCRYPT_NO_MITM:
391 *p_btm_sec_act = BTM_BLE_SEC_ENCRYPT_NO_MITM;
392 break;
393 case GATT_SEC_ENCRYPT_MITM:
394 *p_btm_sec_act = BTM_BLE_SEC_ENCRYPT_MITM;
395 break;
396 default:
397 status = false;
398 break;
399 }
400
401 return status;
402 }
403
404 /** check link security, return true if p_clcb should be added back to queue */
gatt_security_check_start(tGATT_CLCB * p_clcb)405 bool gatt_security_check_start(tGATT_CLCB* p_clcb) {
406 tGATT_TCB* p_tcb = p_clcb->p_tcb;
407 tGATT_SEC_ACTION sec_act_old = gatt_get_sec_act(p_tcb);
408
409 tGATT_SEC_ACTION gatt_sec_act = gatt_determine_sec_act(p_clcb);
410
411 if (sec_act_old == GATT_SEC_NONE) gatt_set_sec_act(p_tcb, gatt_sec_act);
412
413 switch (gatt_sec_act) {
414 case GATT_SEC_SIGN_DATA:
415 VLOG(1) << StringPrintf("%s: Do data signing", __func__);
416 gatt_sign_data(p_clcb);
417 break;
418 case GATT_SEC_ENCRYPT:
419 case GATT_SEC_ENCRYPT_NO_MITM:
420 case GATT_SEC_ENCRYPT_MITM:
421 if (sec_act_old < GATT_SEC_ENCRYPT) {
422 VLOG(1) << StringPrintf("%s: Encrypt now or key upgreade first",
423 __func__);
424 tBTM_BLE_SEC_ACT btm_ble_sec_act;
425 gatt_convert_sec_action(gatt_sec_act, &btm_ble_sec_act);
426 tBTM_STATUS btm_status =
427 BTM_SetEncryption(p_tcb->peer_bda, p_tcb->transport,
428 gatt_enc_cmpl_cback, NULL, btm_ble_sec_act);
429 if ((btm_status != BTM_SUCCESS) && (btm_status != BTM_CMD_STARTED)) {
430 LOG(ERROR) << StringPrintf(
431 "%s BTM_SetEncryption failed btm_status=%d", __func__,
432 btm_status);
433 gatt_set_sec_act(p_tcb, GATT_SEC_NONE);
434 gatt_set_ch_state(p_tcb, GATT_CH_OPEN);
435
436 gatt_end_operation(p_clcb, GATT_INSUF_ENCRYPTION, NULL);
437 return false;
438 }
439 }
440 return true;
441 case GATT_SEC_ENC_PENDING:
442 /* wait for link encrypotion to finish */
443 return true;
444 default:
445 gatt_sec_check_complete(true, p_clcb, gatt_sec_act);
446 break;
447 }
448
449 return false;
450 }
451