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
25 #include <bluetooth/log.h>
26 #include <string.h>
27
28 #include "gatt_api.h"
29 #include "gatt_int.h"
30 #include "internal_include/bt_target.h"
31 #include "osi/include/allocator.h"
32 #include "osi/include/osi.h"
33 #include "stack/btm/btm_ble_sec.h"
34 #include "stack/btm/btm_sec.h"
35 #include "stack/include/bt_hdr.h"
36 #include "stack/include/bt_types.h"
37 #include "stack/include/btm_ble_sec_api.h"
38 #include "types/raw_address.h"
39
40 using namespace bluetooth;
41
42 /*******************************************************************************
43 *
44 * Function gatt_sign_data
45 *
46 * Description This function sign the data for write command.
47 *
48 * Returns true if encrypted, otherwise false.
49 *
50 ******************************************************************************/
gatt_sign_data(tGATT_CLCB * p_clcb)51 static bool gatt_sign_data(tGATT_CLCB* p_clcb) {
52 tGATT_VALUE* p_attr = (tGATT_VALUE*)p_clcb->p_attr_buf;
53 uint8_t *p_data = NULL, *p;
54 uint16_t payload_size = p_clcb->p_tcb->payload_size;
55 bool status = false;
56 uint8_t* p_signature;
57
58 /* do not need to mark channel securoty activity for data signing */
59 gatt_set_sec_act(p_clcb->p_tcb, GATT_SEC_OK);
60
61 p_data =
62 (uint8_t*)osi_malloc(p_attr->len + 3); /* 3 = 2 byte handle + opcode */
63
64 p = p_data;
65 UINT8_TO_STREAM(p, GATT_SIGN_CMD_WRITE);
66 UINT16_TO_STREAM(p, p_attr->handle);
67 ARRAY_TO_STREAM(p, p_attr->value, p_attr->len);
68
69 /* sign data length should be attribulte value length plus 2B handle + 1B op
70 * code */
71 if ((payload_size - GATT_AUTH_SIGN_LEN - 3) < p_attr->len)
72 p_attr->len = payload_size - GATT_AUTH_SIGN_LEN - 3;
73
74 p_signature = p_attr->value + p_attr->len;
75 if (BTM_BleDataSignature(
76 p_clcb->p_tcb->peer_bda, p_data,
77 (uint16_t)(p_attr->len + 3), /* 3 = 2 byte handle + opcode */
78 p_signature)) {
79 p_attr->len += BTM_BLE_AUTH_SIGN_LEN;
80 gatt_set_ch_state(p_clcb->p_tcb, GATT_CH_OPEN);
81 gatt_act_write(p_clcb, GATT_SEC_SIGN_DATA);
82 } else {
83 gatt_end_operation(p_clcb, GATT_INTERNAL_ERROR, NULL);
84 }
85
86 osi_free(p_data);
87
88 return status;
89 }
90
91 /*******************************************************************************
92 *
93 * Function gatt_verify_signature
94 *
95 * Description This function start to verify the sign data when receiving
96 * the data from peer device.
97 *
98 * Returns
99 *
100 ******************************************************************************/
gatt_verify_signature(tGATT_TCB & tcb,uint16_t cid,BT_HDR * p_buf)101 void gatt_verify_signature(tGATT_TCB& tcb, uint16_t cid, BT_HDR* p_buf) {
102 uint16_t cmd_len;
103 uint8_t op_code;
104 uint8_t *p, *p_orig = (uint8_t*)(p_buf + 1) + p_buf->offset;
105 uint32_t counter;
106
107 if (p_buf->len < GATT_AUTH_SIGN_LEN + 4) {
108 log::error("Data length {} less than expected {}", p_buf->len,
109 GATT_AUTH_SIGN_LEN + 4);
110 return;
111 }
112 cmd_len = p_buf->len - GATT_AUTH_SIGN_LEN + 4;
113 p = p_orig + cmd_len - 4;
114 STREAM_TO_UINT32(counter, p);
115
116 if (!BTM_BleVerifySignature(tcb.peer_bda, p_orig, cmd_len, counter, p)) {
117 /* if this is a bad signature, assume from attacker, ignore it */
118 log::error("Signature Verification Failed, data ignored");
119 return;
120 }
121
122 STREAM_TO_UINT8(op_code, p_orig);
123 gatt_server_handle_client_req(tcb, cid, op_code, (uint16_t)(p_buf->len - 1),
124 p_orig);
125 }
126 /*******************************************************************************
127 *
128 * Function gatt_sec_check_complete
129 *
130 * Description security check complete and proceed to data sending action.
131 *
132 * Returns void.
133 *
134 ******************************************************************************/
gatt_sec_check_complete(bool sec_check_ok,tGATT_CLCB * p_clcb,uint8_t sec_act)135 static void gatt_sec_check_complete(bool sec_check_ok, tGATT_CLCB* p_clcb,
136 uint8_t sec_act) {
137 if (p_clcb && p_clcb->p_tcb && p_clcb->p_tcb->pending_enc_clcb.empty()) {
138 gatt_set_sec_act(p_clcb->p_tcb, GATT_SEC_NONE);
139 }
140
141 if (!sec_check_ok) {
142 gatt_end_operation(p_clcb, GATT_AUTH_FAIL, NULL);
143 } else if (p_clcb->operation == GATTC_OPTYPE_WRITE) {
144 gatt_act_write(p_clcb, sec_act);
145 } else if (p_clcb->operation == GATTC_OPTYPE_READ) {
146 gatt_act_read(p_clcb, p_clcb->counter);
147 }
148 }
149 /*******************************************************************************
150 *
151 * Function gatt_enc_cmpl_cback
152 *
153 * Description link encryption complete callback.
154 *
155 * Returns
156 *
157 ******************************************************************************/
gatt_enc_cmpl_cback(RawAddress bd_addr,tBT_TRANSPORT transport,void *,tBTM_STATUS result)158 static void gatt_enc_cmpl_cback(RawAddress bd_addr, tBT_TRANSPORT transport,
159 void* /* p_ref_data */, tBTM_STATUS result) {
160 log::verbose("");
161 tGATT_TCB* p_tcb = gatt_find_tcb_by_addr(bd_addr, transport);
162 if (!p_tcb) {
163 log::error("enc callback for unknown bd_addr");
164 return;
165 }
166
167 if (gatt_get_sec_act(p_tcb) == GATT_SEC_ENC_PENDING) return;
168
169 if (p_tcb->pending_enc_clcb.empty()) {
170 log::error("no operation waiting for encrypting");
171 return;
172 }
173
174 tGATT_CLCB* p_clcb = p_tcb->pending_enc_clcb.front();
175 p_tcb->pending_enc_clcb.pop_front();
176
177 if (p_clcb != NULL) {
178 bool status = false;
179 if (result == BTM_SUCCESS) {
180 if (gatt_get_sec_act(p_tcb) == GATT_SEC_ENCRYPT_MITM) {
181 status = BTM_IsLinkKeyAuthed(bd_addr, transport);
182 } else {
183 status = true;
184 }
185 }
186
187 gatt_sec_check_complete(status, p_clcb, p_tcb->sec_act);
188 }
189
190 /* start all other pending operation in queue */
191 std::deque<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_front();
195 if (p_clcb != NULL && gatt_security_check_start(p_clcb))
196 new_pending_clcbs.push_back(p_clcb);
197 }
198 p_tcb->pending_enc_clcb = new_pending_clcbs;
199 }
200
201 /*******************************************************************************
202 *
203 * Function gatt_notify_enc_cmpl
204 *
205 * Description link encryption complete notification for all encryption
206 * process initiated outside GATT.
207 *
208 * Returns
209 *
210 ******************************************************************************/
gatt_notify_enc_cmpl(const RawAddress & bd_addr)211 void gatt_notify_enc_cmpl(const RawAddress& bd_addr) {
212 tGATT_TCB* p_tcb = gatt_find_tcb_by_addr(bd_addr, BT_TRANSPORT_LE);
213 if (!p_tcb) {
214 log::verbose("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::deque<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_front();
232 if (p_clcb != NULL && gatt_security_check_start(p_clcb))
233 new_pending_clcbs.push_back(p_clcb);
234 }
235 p_tcb->pending_enc_clcb = new_pending_clcbs;
236 }
237 }
238 /*******************************************************************************
239 *
240 * Function gatt_set_sec_act
241 *
242 * Description This function set the sec_act in clcb
243 *
244 * Returns none
245 *
246 ******************************************************************************/
gatt_set_sec_act(tGATT_TCB * p_tcb,tGATT_SEC_ACTION sec_act)247 void gatt_set_sec_act(tGATT_TCB* p_tcb, tGATT_SEC_ACTION sec_act) {
248 if (p_tcb) {
249 p_tcb->sec_act = sec_act;
250 }
251 }
252 /*******************************************************************************
253 *
254 * Function gatt_get_sec_act
255 *
256 * Description This function get the sec_act in clcb
257 *
258 * Returns none
259 *
260 ******************************************************************************/
gatt_get_sec_act(tGATT_TCB * p_tcb)261 tGATT_SEC_ACTION gatt_get_sec_act(tGATT_TCB* p_tcb) {
262 tGATT_SEC_ACTION sec_act = GATT_SEC_NONE;
263 if (p_tcb) {
264 sec_act = p_tcb->sec_act;
265 }
266 return sec_act;
267 }
268 /**
269 * This routine determine the security action based on auth_request and current
270 * link status. Returns tGATT_SEC_ACTION (security action)
271 */
gatt_determine_sec_act(tGATT_CLCB * p_clcb)272 tGATT_SEC_ACTION gatt_determine_sec_act(tGATT_CLCB* p_clcb) {
273 tGATT_SEC_ACTION act = GATT_SEC_OK;
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_BLE_SEC_REQ_ACT_NONE;
281
282 if (auth_req == GATT_AUTH_REQ_NONE) return act;
283
284 btm_ble_link_sec_check(p_tcb->peer_bda, auth_req, &sec_act);
285
286 /* if a encryption is pending, need to wait */
287 if (sec_act == BTM_BLE_SEC_REQ_ACT_DISCARD && auth_req != GATT_AUTH_REQ_NONE)
288 return GATT_SEC_ENC_PENDING;
289
290 is_link_key_known =
291 BTM_IsLinkKeyKnown(p_tcb->peer_bda, p_clcb->p_tcb->transport);
292 is_link_encrypted =
293 BTM_IsEncrypted(p_tcb->peer_bda, p_clcb->p_tcb->transport);
294 is_key_mitm = BTM_IsLinkKeyAuthed(p_tcb->peer_bda, p_clcb->p_tcb->transport);
295
296 /* first check link key upgrade required or not */
297 switch (auth_req) {
298 case GATT_AUTH_REQ_MITM:
299 case GATT_AUTH_REQ_SIGNED_MITM:
300 if (!is_key_mitm) act = GATT_SEC_ENCRYPT_MITM;
301 break;
302
303 case GATT_AUTH_REQ_NO_MITM:
304 case GATT_AUTH_REQ_SIGNED_NO_MITM:
305 if (!is_link_key_known) act = GATT_SEC_ENCRYPT_NO_MITM;
306 break;
307 default:
308 break;
309 }
310
311 /* now check link needs to be encrypted or not if the link key upgrade is not
312 * required */
313 if (act == GATT_SEC_OK) {
314 if (p_tcb->transport == BT_TRANSPORT_LE &&
315 (p_clcb->operation == GATTC_OPTYPE_WRITE) &&
316 (p_clcb->op_subtype == GATT_WRITE_NO_RSP)) {
317 /* this is a write command request
318 check data signing required or not */
319 if (!is_link_encrypted) {
320 btm_ble_get_enc_key_type(p_tcb->peer_bda, &key_type);
321
322 if ((key_type & BTM_LE_KEY_LCSRK) &&
323 ((auth_req == GATT_AUTH_REQ_SIGNED_NO_MITM) ||
324 (auth_req == GATT_AUTH_REQ_SIGNED_MITM))) {
325 act = GATT_SEC_SIGN_DATA;
326 } else {
327 act = GATT_SEC_ENCRYPT;
328 }
329 }
330 } else {
331 if (!is_link_encrypted) {
332 act = GATT_SEC_ENCRYPT;
333 }
334 }
335 }
336
337 return act;
338 }
339
340 /*******************************************************************************
341 *
342 * Function gatt_get_link_encrypt_status
343 *
344 * Description This routine get the encryption status of the specified link
345 *
346 *
347 * Returns tGATT_STATUS link encryption status
348 *
349 ******************************************************************************/
gatt_get_link_encrypt_status(tGATT_TCB & tcb)350 tGATT_STATUS gatt_get_link_encrypt_status(tGATT_TCB& tcb) {
351 tGATT_STATUS encrypt_status = GATT_NOT_ENCRYPTED;
352
353 bool encrypted = BTM_IsEncrypted(tcb.peer_bda, tcb.transport);
354 bool link_key_known = BTM_IsLinkKeyKnown(tcb.peer_bda, tcb.transport);
355 bool link_key_authed = BTM_IsLinkKeyAuthed(tcb.peer_bda, tcb.transport);
356
357 if (encrypted && link_key_known) {
358 encrypt_status = GATT_ENCRYPED_NO_MITM;
359 if (link_key_authed) {
360 encrypt_status = GATT_ENCRYPED_MITM;
361 }
362 }
363
364 log::verbose("gatt_get_link_encrypt_status status=0x{:x}", encrypt_status);
365 return encrypt_status;
366 }
367
368 /*******************************************************************************
369 *
370 * Function gatt_convert_sec_action
371 *
372 * Description Convert GATT security action enum into equivalent
373 * BTM BLE security action enum
374 *
375 * Returns bool true - conversation is successful
376 *
377 ******************************************************************************/
gatt_convert_sec_action(tGATT_SEC_ACTION gatt_sec_act,tBTM_BLE_SEC_ACT * p_btm_sec_act)378 static bool gatt_convert_sec_action(tGATT_SEC_ACTION gatt_sec_act,
379 tBTM_BLE_SEC_ACT* p_btm_sec_act) {
380 bool status = true;
381 switch (gatt_sec_act) {
382 case GATT_SEC_ENCRYPT:
383 *p_btm_sec_act = BTM_BLE_SEC_ENCRYPT;
384 break;
385 case GATT_SEC_ENCRYPT_NO_MITM:
386 *p_btm_sec_act = BTM_BLE_SEC_ENCRYPT_NO_MITM;
387 break;
388 case GATT_SEC_ENCRYPT_MITM:
389 *p_btm_sec_act = BTM_BLE_SEC_ENCRYPT_MITM;
390 break;
391 default:
392 status = false;
393 break;
394 }
395
396 return status;
397 }
398
399 /** check link security, return true if p_clcb should be added back to queue */
gatt_security_check_start(tGATT_CLCB * p_clcb)400 bool gatt_security_check_start(tGATT_CLCB* p_clcb) {
401 tGATT_TCB* p_tcb = p_clcb->p_tcb;
402 tGATT_SEC_ACTION sec_act_old = gatt_get_sec_act(p_tcb);
403
404 tGATT_SEC_ACTION gatt_sec_act = gatt_determine_sec_act(p_clcb);
405
406 if (sec_act_old == GATT_SEC_NONE) gatt_set_sec_act(p_tcb, gatt_sec_act);
407
408 switch (gatt_sec_act) {
409 case GATT_SEC_SIGN_DATA:
410 log::verbose("Do data signing");
411 gatt_sign_data(p_clcb);
412 break;
413 case GATT_SEC_ENCRYPT:
414 case GATT_SEC_ENCRYPT_NO_MITM:
415 case GATT_SEC_ENCRYPT_MITM:
416 if (sec_act_old < GATT_SEC_ENCRYPT) {
417 log::verbose("Encrypt now or key upgreade first");
418 tBTM_BLE_SEC_ACT btm_ble_sec_act;
419 gatt_convert_sec_action(gatt_sec_act, &btm_ble_sec_act);
420 tBTM_STATUS btm_status =
421 BTM_SetEncryption(p_tcb->peer_bda, p_tcb->transport,
422 gatt_enc_cmpl_cback, NULL, btm_ble_sec_act);
423 if ((btm_status != BTM_SUCCESS) && (btm_status != BTM_CMD_STARTED)) {
424 log::error("BTM_SetEncryption failed btm_status={}", btm_status);
425 gatt_set_sec_act(p_tcb, GATT_SEC_NONE);
426 gatt_set_ch_state(p_tcb, GATT_CH_OPEN);
427
428 gatt_end_operation(p_clcb, GATT_INSUF_ENCRYPTION, NULL);
429 return false;
430 }
431 }
432 return true;
433 case GATT_SEC_ENC_PENDING:
434 /* wait for link encrypotion to finish */
435 return true;
436 default:
437 gatt_sec_check_complete(true, p_clcb, gatt_sec_act);
438 break;
439 }
440
441 return false;
442 }
443