1 /*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <ctype.h>
18 #include <endian.h>
19 #include <errno.h>
20 #include <limits.h>
21 #include <stdarg.h>
22 #include <stdlib.h>
23 #include <string.h>
24 #include <sys/prctl.h>
25 #include <sys/uio.h>
26 #include <syslog.h>
27
28 #include <fstream>
29 #include <sstream>
30
31 #include <android-base/macros.h>
32 #include <log/log_properties.h>
33 #include <private/android_filesystem_config.h>
34 #include <private/android_logger.h>
35
36 #include "LogAudit.h"
37 #include "LogBuffer.h"
38 #include "LogKlog.h"
39 #include "LogReader.h"
40 #include "LogUtils.h"
41 #include "libaudit.h"
42
43 #define KMSG_PRIORITY(PRI) \
44 '<', '0' + LOG_MAKEPRI(LOG_AUTH, LOG_PRI(PRI)) / 10, \
45 '0' + LOG_MAKEPRI(LOG_AUTH, LOG_PRI(PRI)) % 10, '>'
46
LogAudit(LogBuffer * buf,LogReader * reader,int fdDmesg)47 LogAudit::LogAudit(LogBuffer* buf, LogReader* reader, int fdDmesg)
48 : SocketListener(getLogSocket(), false),
49 logbuf(buf),
50 reader(reader),
51 fdDmesg(fdDmesg),
52 main(__android_logger_property_get_bool("ro.logd.auditd.main",
53 BOOL_DEFAULT_TRUE)),
54 events(__android_logger_property_get_bool("ro.logd.auditd.events",
55 BOOL_DEFAULT_TRUE)),
56 initialized(false) {
57 static const char auditd_message[] = { KMSG_PRIORITY(LOG_INFO),
58 'l',
59 'o',
60 'g',
61 'd',
62 '.',
63 'a',
64 'u',
65 'd',
66 'i',
67 't',
68 'd',
69 ':',
70 ' ',
71 's',
72 't',
73 'a',
74 'r',
75 't',
76 '\n' };
77 write(fdDmesg, auditd_message, sizeof(auditd_message));
78 }
79
onDataAvailable(SocketClient * cli)80 bool LogAudit::onDataAvailable(SocketClient* cli) {
81 if (!initialized) {
82 prctl(PR_SET_NAME, "logd.auditd");
83 initialized = true;
84 }
85
86 struct audit_message rep;
87
88 rep.nlh.nlmsg_type = 0;
89 rep.nlh.nlmsg_len = 0;
90 rep.data[0] = '\0';
91
92 if (audit_get_reply(cli->getSocket(), &rep, GET_REPLY_BLOCKING, 0) < 0) {
93 SLOGE("Failed on audit_get_reply with error: %s", strerror(errno));
94 return false;
95 }
96
97 logPrint("type=%d %.*s", rep.nlh.nlmsg_type, rep.nlh.nlmsg_len, rep.data);
98
99 return true;
100 }
101
hasMetadata(char * str,int str_len)102 static inline bool hasMetadata(char* str, int str_len) {
103 // need to check and see if str already contains bug metadata from
104 // possibility of stuttering if log audit crashes and then reloads kernel
105 // messages. Kernel denials that contain metadata will either end in
106 // "b/[0-9]+$" or "b/[0-9]+ duplicate messages suppressed$" which will put
107 // a '/' character at either 9 or 39 indices away from the end of the str.
108 return str_len >= 39 &&
109 (str[str_len - 9] == '/' || str[str_len - 39] == '/');
110 }
111
populateDenialMap()112 std::map<std::string, std::string> LogAudit::populateDenialMap() {
113 std::ifstream bug_file("/system/etc/selinux/selinux_denial_metadata");
114 std::string line;
115 // allocate a map for the static map pointer in logParse to keep track of,
116 // this function only runs once
117 std::map<std::string, std::string> denial_to_bug;
118 if (bug_file.good()) {
119 std::string scontext;
120 std::string tcontext;
121 std::string tclass;
122 std::string bug_num;
123 while (std::getline(bug_file, line)) {
124 std::stringstream split_line(line);
125 split_line >> scontext >> tcontext >> tclass >> bug_num;
126 denial_to_bug.emplace(scontext + tcontext + tclass, bug_num);
127 }
128 }
129 return denial_to_bug;
130 }
131
denialParse(const std::string & denial,char terminator,const std::string & search_term)132 std::string LogAudit::denialParse(const std::string& denial, char terminator,
133 const std::string& search_term) {
134 size_t start_index = denial.find(search_term);
135 if (start_index != std::string::npos) {
136 start_index += search_term.length();
137 return denial.substr(
138 start_index, denial.find(terminator, start_index) - start_index);
139 }
140 return "";
141 }
142
logParse(const std::string & string,std::string * bug_num)143 void LogAudit::logParse(const std::string& string, std::string* bug_num) {
144 if (!__android_log_is_debuggable()) {
145 bug_num->assign("");
146 return;
147 }
148 static std::map<std::string, std::string> denial_to_bug =
149 populateDenialMap();
150 std::string scontext = denialParse(string, ':', "scontext=u:object_r:");
151 std::string tcontext = denialParse(string, ':', "tcontext=u:object_r:");
152 std::string tclass = denialParse(string, ' ', "tclass=");
153 if (scontext.empty()) {
154 scontext = denialParse(string, ':', "scontext=u:r:");
155 }
156 if (tcontext.empty()) {
157 tcontext = denialParse(string, ':', "tcontext=u:r:");
158 }
159 auto search = denial_to_bug.find(scontext + tcontext + tclass);
160 if (search != denial_to_bug.end()) {
161 bug_num->assign(" b/" + search->second);
162 } else {
163 bug_num->assign("");
164 }
165 }
166
logPrint(const char * fmt,...)167 int LogAudit::logPrint(const char* fmt, ...) {
168 if (fmt == NULL) {
169 return -EINVAL;
170 }
171
172 va_list args;
173
174 char* str = NULL;
175 va_start(args, fmt);
176 int rc = vasprintf(&str, fmt, args);
177 va_end(args);
178
179 if (rc < 0) {
180 return rc;
181 }
182 char* cp;
183 // Work around kernels missing
184 // https://github.com/torvalds/linux/commit/b8f89caafeb55fba75b74bea25adc4e4cd91be67
185 // Such kernels improperly add newlines inside audit messages.
186 while ((cp = strchr(str, '\n'))) {
187 *cp = ' ';
188 }
189
190 while ((cp = strstr(str, " "))) {
191 memmove(cp, cp + 1, strlen(cp + 1) + 1);
192 }
193 bool info = strstr(str, " permissive=1") || strstr(str, " policy loaded ");
194 static std::string bug_metadata;
195 if ((fdDmesg >= 0) && initialized) {
196 struct iovec iov[4];
197 static const char log_info[] = { KMSG_PRIORITY(LOG_INFO) };
198 static const char log_warning[] = { KMSG_PRIORITY(LOG_WARNING) };
199 static const char newline[] = "\n";
200
201 // Dedupe messages, checking for identical messages starting with avc:
202 static unsigned count;
203 static char* last_str;
204 static bool last_info;
205
206 if (last_str != NULL) {
207 static const char avc[] = "): avc: ";
208 char* avcl = strstr(last_str, avc);
209 bool skip = false;
210
211 if (avcl) {
212 char* avcr = strstr(str, avc);
213
214 skip = avcr &&
215 !fastcmp<strcmp>(avcl + strlen(avc), avcr + strlen(avc));
216 if (skip) {
217 ++count;
218 free(last_str);
219 last_str = strdup(str);
220 last_info = info;
221 }
222 }
223 if (!skip) {
224 static const char resume[] = " duplicate messages suppressed\n";
225 iov[0].iov_base = last_info ? const_cast<char*>(log_info)
226 : const_cast<char*>(log_warning);
227 iov[0].iov_len =
228 last_info ? sizeof(log_info) : sizeof(log_warning);
229 iov[1].iov_base = last_str;
230 iov[1].iov_len = strlen(last_str);
231 iov[2].iov_base = const_cast<char*>(bug_metadata.c_str());
232 iov[2].iov_len = bug_metadata.length();
233 if (count > 1) {
234 iov[3].iov_base = const_cast<char*>(resume);
235 iov[3].iov_len = strlen(resume);
236 } else {
237 iov[3].iov_base = const_cast<char*>(newline);
238 iov[3].iov_len = strlen(newline);
239 }
240
241 writev(fdDmesg, iov, arraysize(iov));
242 free(last_str);
243 last_str = NULL;
244 }
245 }
246 if (last_str == NULL) {
247 count = 0;
248 last_str = strdup(str);
249 last_info = info;
250 }
251 if (count == 0) {
252 logParse(str, &bug_metadata);
253 iov[0].iov_base = info ? const_cast<char*>(log_info)
254 : const_cast<char*>(log_warning);
255 iov[0].iov_len = info ? sizeof(log_info) : sizeof(log_warning);
256 iov[1].iov_base = str;
257 iov[1].iov_len = strlen(str);
258 iov[2].iov_base = const_cast<char*>(bug_metadata.c_str());
259 iov[2].iov_len = bug_metadata.length();
260 iov[3].iov_base = const_cast<char*>(newline);
261 iov[3].iov_len = strlen(newline);
262
263 writev(fdDmesg, iov, arraysize(iov));
264 }
265 }
266
267 if (!main && !events) {
268 free(str);
269 return 0;
270 }
271
272 pid_t pid = getpid();
273 pid_t tid = gettid();
274 uid_t uid = AID_LOGD;
275 log_time now;
276
277 static const char audit_str[] = " audit(";
278 char* timeptr = strstr(str, audit_str);
279 if (timeptr &&
280 ((cp = now.strptime(timeptr + sizeof(audit_str) - 1, "%s.%q"))) &&
281 (*cp == ':')) {
282 memcpy(timeptr + sizeof(audit_str) - 1, "0.0", 3);
283 memmove(timeptr + sizeof(audit_str) - 1 + 3, cp, strlen(cp) + 1);
284 if (!isMonotonic()) {
285 if (android::isMonotonic(now)) {
286 LogKlog::convertMonotonicToReal(now);
287 }
288 } else {
289 if (!android::isMonotonic(now)) {
290 LogKlog::convertRealToMonotonic(now);
291 }
292 }
293 } else if (isMonotonic()) {
294 now = log_time(CLOCK_MONOTONIC);
295 } else {
296 now = log_time(CLOCK_REALTIME);
297 }
298
299 static const char pid_str[] = " pid=";
300 char* pidptr = strstr(str, pid_str);
301 if (pidptr && isdigit(pidptr[sizeof(pid_str) - 1])) {
302 cp = pidptr + sizeof(pid_str) - 1;
303 pid = 0;
304 while (isdigit(*cp)) {
305 pid = (pid * 10) + (*cp - '0');
306 ++cp;
307 }
308 tid = pid;
309 logbuf->wrlock();
310 uid = logbuf->pidToUid(pid);
311 logbuf->unlock();
312 memmove(pidptr, cp, strlen(cp) + 1);
313 }
314
315 // log to events
316
317 size_t str_len = strnlen(str, LOGGER_ENTRY_MAX_PAYLOAD);
318 if (((fdDmesg < 0) || !initialized) && !hasMetadata(str, str_len))
319 logParse(str, &bug_metadata);
320 str_len = (str_len + bug_metadata.length() <= LOGGER_ENTRY_MAX_PAYLOAD)
321 ? str_len + bug_metadata.length()
322 : LOGGER_ENTRY_MAX_PAYLOAD;
323 size_t message_len = str_len + sizeof(android_log_event_string_t);
324
325 log_mask_t notify = 0;
326
327 if (events) { // begin scope for event buffer
328 uint32_t buffer[(message_len + sizeof(uint32_t) - 1) / sizeof(uint32_t)];
329
330 android_log_event_string_t* event =
331 reinterpret_cast<android_log_event_string_t*>(buffer);
332 event->header.tag = htole32(AUDITD_LOG_TAG);
333 event->type = EVENT_TYPE_STRING;
334 event->length = htole32(str_len);
335 memcpy(event->data, str, str_len - bug_metadata.length());
336 memcpy(event->data + str_len - bug_metadata.length(),
337 bug_metadata.c_str(), bug_metadata.length());
338
339 rc = logbuf->log(
340 LOG_ID_EVENTS, now, uid, pid, tid, reinterpret_cast<char*>(event),
341 (message_len <= USHRT_MAX) ? (unsigned short)message_len
342 : USHRT_MAX);
343 if (rc >= 0) {
344 notify |= 1 << LOG_ID_EVENTS;
345 }
346 // end scope for event buffer
347 }
348
349 // log to main
350
351 static const char comm_str[] = " comm=\"";
352 const char* comm = strstr(str, comm_str);
353 const char* estr = str + strlen(str);
354 const char* commfree = NULL;
355 if (comm) {
356 estr = comm;
357 comm += sizeof(comm_str) - 1;
358 } else if (pid == getpid()) {
359 pid = tid;
360 comm = "auditd";
361 } else {
362 logbuf->wrlock();
363 comm = commfree = logbuf->pidToName(pid);
364 logbuf->unlock();
365 if (!comm) {
366 comm = "unknown";
367 }
368 }
369
370 const char* ecomm = strchr(comm, '"');
371 if (ecomm) {
372 ++ecomm;
373 str_len = ecomm - comm;
374 } else {
375 str_len = strlen(comm) + 1;
376 ecomm = "";
377 }
378 size_t prefix_len = estr - str;
379 if (prefix_len > LOGGER_ENTRY_MAX_PAYLOAD) {
380 prefix_len = LOGGER_ENTRY_MAX_PAYLOAD;
381 }
382 size_t suffix_len = strnlen(ecomm, LOGGER_ENTRY_MAX_PAYLOAD - prefix_len);
383 message_len = str_len + prefix_len + suffix_len + bug_metadata.length() + 2;
384
385 if (main) { // begin scope for main buffer
386 char newstr[message_len];
387
388 *newstr = info ? ANDROID_LOG_INFO : ANDROID_LOG_WARN;
389 strlcpy(newstr + 1, comm, str_len);
390 strncpy(newstr + 1 + str_len, str, prefix_len);
391 strncpy(newstr + 1 + str_len + prefix_len, ecomm, suffix_len);
392 strncpy(newstr + 1 + str_len + prefix_len + suffix_len,
393 bug_metadata.c_str(), bug_metadata.length());
394
395 rc = logbuf->log(LOG_ID_MAIN, now, uid, pid, tid, newstr,
396 (message_len <= USHRT_MAX) ? (unsigned short)message_len
397 : USHRT_MAX);
398
399 if (rc >= 0) {
400 notify |= 1 << LOG_ID_MAIN;
401 }
402 // end scope for main buffer
403 }
404
405 free(const_cast<char*>(commfree));
406 free(str);
407
408 if (notify) {
409 reader->notifyNewLog(notify);
410 if (rc < 0) {
411 rc = message_len;
412 }
413 }
414
415 return rc;
416 }
417
log(char * buf,size_t len)418 int LogAudit::log(char* buf, size_t len) {
419 char* audit = strstr(buf, " audit(");
420 if (!audit || (audit >= &buf[len])) {
421 return 0;
422 }
423
424 *audit = '\0';
425
426 int rc;
427 char* type = strstr(buf, "type=");
428 if (type && (type < &buf[len])) {
429 rc = logPrint("%s %s", type, audit + 1);
430 } else {
431 rc = logPrint("%s", audit + 1);
432 }
433 *audit = ' ';
434 return rc;
435 }
436
getLogSocket()437 int LogAudit::getLogSocket() {
438 int fd = audit_open();
439 if (fd < 0) {
440 return fd;
441 }
442 if (audit_setup(fd, getpid()) < 0) {
443 audit_close(fd);
444 fd = -1;
445 }
446 return fd;
447 }
448