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 <stdint.h>
23 #include <stdlib.h>
24 #include <string.h>
25 #include <sys/prctl.h>
26 #include <sys/uio.h>
27 #include <syslog.h>
28
29 #include <fstream>
30 #include <sstream>
31
32 #include <android-base/macros.h>
33 #include <log/log_properties.h>
34 #include <private/android_filesystem_config.h>
35 #include <private/android_logger.h>
36
37 #include "LogAudit.h"
38 #include "LogBuffer.h"
39 #include "LogKlog.h"
40 #include "LogReader.h"
41 #include "LogUtils.h"
42 #include "libaudit.h"
43
44 #define KMSG_PRIORITY(PRI) \
45 '<', '0' + LOG_MAKEPRI(LOG_AUTH, LOG_PRI(PRI)) / 10, \
46 '0' + LOG_MAKEPRI(LOG_AUTH, LOG_PRI(PRI)) % 10, '>'
47
LogAudit(LogBuffer * buf,LogReader * reader,int fdDmesg)48 LogAudit::LogAudit(LogBuffer* buf, LogReader* reader, int fdDmesg)
49 : SocketListener(getLogSocket(), false),
50 logbuf(buf),
51 reader(reader),
52 fdDmesg(fdDmesg),
53 main(__android_logger_property_get_bool("ro.logd.auditd.main",
54 BOOL_DEFAULT_TRUE)),
55 events(__android_logger_property_get_bool("ro.logd.auditd.events",
56 BOOL_DEFAULT_TRUE)),
57 initialized(false) {
58 static const char auditd_message[] = { KMSG_PRIORITY(LOG_INFO),
59 'l',
60 'o',
61 'g',
62 'd',
63 '.',
64 'a',
65 'u',
66 'd',
67 'i',
68 't',
69 'd',
70 ':',
71 ' ',
72 's',
73 't',
74 'a',
75 'r',
76 't',
77 '\n' };
78 write(fdDmesg, auditd_message, sizeof(auditd_message));
79 }
80
onDataAvailable(SocketClient * cli)81 bool LogAudit::onDataAvailable(SocketClient* cli) {
82 if (!initialized) {
83 prctl(PR_SET_NAME, "logd.auditd");
84 initialized = true;
85 }
86
87 struct audit_message rep;
88
89 rep.nlh.nlmsg_type = 0;
90 rep.nlh.nlmsg_len = 0;
91 rep.data[0] = '\0';
92
93 if (audit_get_reply(cli->getSocket(), &rep, GET_REPLY_BLOCKING, 0) < 0) {
94 SLOGE("Failed on audit_get_reply with error: %s", strerror(errno));
95 return false;
96 }
97
98 logPrint("type=%d %.*s", rep.nlh.nlmsg_type, rep.nlh.nlmsg_len, rep.data);
99
100 return true;
101 }
102
hasMetadata(char * str,int str_len)103 static inline bool hasMetadata(char* str, int str_len) {
104 // need to check and see if str already contains bug metadata from
105 // possibility of stuttering if log audit crashes and then reloads kernel
106 // messages. Kernel denials that contain metadata will either end in
107 // "b/[0-9]+$" or "b/[0-9]+ duplicate messages suppressed$" which will put
108 // a '/' character at either 9 or 39 indices away from the end of the str.
109 return str_len >= 39 &&
110 (str[str_len - 9] == '/' || str[str_len - 39] == '/');
111 }
112
populateDenialMap()113 std::map<std::string, std::string> LogAudit::populateDenialMap() {
114 std::ifstream bug_file("/vendor/etc/selinux/selinux_denial_metadata");
115 std::string line;
116 // allocate a map for the static map pointer in auditParse to keep track of,
117 // this function only runs once
118 std::map<std::string, std::string> denial_to_bug;
119 if (bug_file.good()) {
120 std::string scontext;
121 std::string tcontext;
122 std::string tclass;
123 std::string bug_num;
124 while (std::getline(bug_file, line)) {
125 std::stringstream split_line(line);
126 split_line >> scontext >> tcontext >> tclass >> bug_num;
127 denial_to_bug.emplace(scontext + tcontext + tclass, bug_num);
128 }
129 }
130 return denial_to_bug;
131 }
132
denialParse(const std::string & denial,char terminator,const std::string & search_term)133 std::string LogAudit::denialParse(const std::string& denial, char terminator,
134 const std::string& search_term) {
135 size_t start_index = denial.find(search_term);
136 if (start_index != std::string::npos) {
137 start_index += search_term.length();
138 return denial.substr(
139 start_index, denial.find(terminator, start_index) - start_index);
140 }
141 return "";
142 }
143
auditParse(const std::string & string,uid_t uid,std::string * bug_num)144 void LogAudit::auditParse(const std::string& string, uid_t uid,
145 std::string* bug_num) {
146 static std::map<std::string, std::string> denial_to_bug =
147 populateDenialMap();
148 std::string scontext = denialParse(string, ':', "scontext=u:object_r:");
149 std::string tcontext = denialParse(string, ':', "tcontext=u:object_r:");
150 std::string tclass = denialParse(string, ' ', "tclass=");
151 if (scontext.empty()) {
152 scontext = denialParse(string, ':', "scontext=u:r:");
153 }
154 if (tcontext.empty()) {
155 tcontext = denialParse(string, ':', "tcontext=u:r:");
156 }
157 auto search = denial_to_bug.find(scontext + tcontext + tclass);
158 if (search != denial_to_bug.end()) {
159 bug_num->assign(" " + search->second);
160 } else {
161 bug_num->assign("");
162 }
163
164 // Ensure the uid name is not null before passing it to the bug string.
165 if (uid >= AID_APP_START && uid <= AID_APP_END) {
166 char* uidname = android::uidToName(uid);
167 if (uidname) {
168 bug_num->append(" app=");
169 bug_num->append(uidname);
170 free(uidname);
171 }
172 }
173 }
174
logPrint(const char * fmt,...)175 int LogAudit::logPrint(const char* fmt, ...) {
176 if (fmt == nullptr) {
177 return -EINVAL;
178 }
179
180 va_list args;
181
182 char* str = nullptr;
183 va_start(args, fmt);
184 int rc = vasprintf(&str, fmt, args);
185 va_end(args);
186
187 if (rc < 0) {
188 return rc;
189 }
190 char* cp;
191 // Work around kernels missing
192 // https://github.com/torvalds/linux/commit/b8f89caafeb55fba75b74bea25adc4e4cd91be67
193 // Such kernels improperly add newlines inside audit messages.
194 while ((cp = strchr(str, '\n'))) {
195 *cp = ' ';
196 }
197
198 while ((cp = strstr(str, " "))) {
199 memmove(cp, cp + 1, strlen(cp + 1) + 1);
200 }
201 pid_t pid = getpid();
202 pid_t tid = gettid();
203 uid_t uid = AID_LOGD;
204 static const char pid_str[] = " pid=";
205 char* pidptr = strstr(str, pid_str);
206 if (pidptr && isdigit(pidptr[sizeof(pid_str) - 1])) {
207 cp = pidptr + sizeof(pid_str) - 1;
208 pid = 0;
209 while (isdigit(*cp)) {
210 pid = (pid * 10) + (*cp - '0');
211 ++cp;
212 }
213 tid = pid;
214 logbuf->wrlock();
215 uid = logbuf->pidToUid(pid);
216 logbuf->unlock();
217 memmove(pidptr, cp, strlen(cp) + 1);
218 }
219
220 bool info = strstr(str, " permissive=1") || strstr(str, " policy loaded ");
221 static std::string denial_metadata;
222 if ((fdDmesg >= 0) && initialized) {
223 struct iovec iov[4];
224 static const char log_info[] = { KMSG_PRIORITY(LOG_INFO) };
225 static const char log_warning[] = { KMSG_PRIORITY(LOG_WARNING) };
226 static const char newline[] = "\n";
227
228 auditParse(str, uid, &denial_metadata);
229 iov[0].iov_base = info ? const_cast<char*>(log_info) : const_cast<char*>(log_warning);
230 iov[0].iov_len = info ? sizeof(log_info) : sizeof(log_warning);
231 iov[1].iov_base = str;
232 iov[1].iov_len = strlen(str);
233 iov[2].iov_base = const_cast<char*>(denial_metadata.c_str());
234 iov[2].iov_len = denial_metadata.length();
235 iov[3].iov_base = const_cast<char*>(newline);
236 iov[3].iov_len = strlen(newline);
237
238 writev(fdDmesg, iov, arraysize(iov));
239 }
240
241 if (!main && !events) {
242 free(str);
243 return 0;
244 }
245
246 log_time now(log_time::EPOCH);
247
248 static const char audit_str[] = " audit(";
249 char* timeptr = strstr(str, audit_str);
250 if (timeptr &&
251 ((cp = now.strptime(timeptr + sizeof(audit_str) - 1, "%s.%q"))) &&
252 (*cp == ':')) {
253 memcpy(timeptr + sizeof(audit_str) - 1, "0.0", 3);
254 memmove(timeptr + sizeof(audit_str) - 1 + 3, cp, strlen(cp) + 1);
255 if (!isMonotonic()) {
256 if (android::isMonotonic(now)) {
257 LogKlog::convertMonotonicToReal(now);
258 }
259 } else {
260 if (!android::isMonotonic(now)) {
261 LogKlog::convertRealToMonotonic(now);
262 }
263 }
264 } else if (isMonotonic()) {
265 now = log_time(CLOCK_MONOTONIC);
266 } else {
267 now = log_time(CLOCK_REALTIME);
268 }
269
270 // log to events
271
272 size_t str_len = strnlen(str, LOGGER_ENTRY_MAX_PAYLOAD);
273 if (((fdDmesg < 0) || !initialized) && !hasMetadata(str, str_len))
274 auditParse(str, uid, &denial_metadata);
275 str_len = (str_len + denial_metadata.length() <= LOGGER_ENTRY_MAX_PAYLOAD)
276 ? str_len + denial_metadata.length()
277 : LOGGER_ENTRY_MAX_PAYLOAD;
278 size_t message_len = str_len + sizeof(android_log_event_string_t);
279
280 log_mask_t notify = 0;
281
282 if (events) { // begin scope for event buffer
283 uint32_t buffer[(message_len + sizeof(uint32_t) - 1) / sizeof(uint32_t)];
284
285 android_log_event_string_t* event =
286 reinterpret_cast<android_log_event_string_t*>(buffer);
287 event->header.tag = htole32(AUDITD_LOG_TAG);
288 event->type = EVENT_TYPE_STRING;
289 event->length = htole32(str_len);
290 memcpy(event->data, str, str_len - denial_metadata.length());
291 memcpy(event->data + str_len - denial_metadata.length(),
292 denial_metadata.c_str(), denial_metadata.length());
293
294 rc = logbuf->log(
295 LOG_ID_EVENTS, now, uid, pid, tid, reinterpret_cast<char*>(event),
296 (message_len <= UINT16_MAX) ? (uint16_t)message_len : UINT16_MAX);
297 if (rc >= 0) {
298 notify |= 1 << LOG_ID_EVENTS;
299 }
300 // end scope for event buffer
301 }
302
303 // log to main
304
305 static const char comm_str[] = " comm=\"";
306 const char* comm = strstr(str, comm_str);
307 const char* estr = str + strlen(str);
308 const char* commfree = nullptr;
309 if (comm) {
310 estr = comm;
311 comm += sizeof(comm_str) - 1;
312 } else if (pid == getpid()) {
313 pid = tid;
314 comm = "auditd";
315 } else {
316 logbuf->wrlock();
317 comm = commfree = logbuf->pidToName(pid);
318 logbuf->unlock();
319 if (!comm) {
320 comm = "unknown";
321 }
322 }
323
324 const char* ecomm = strchr(comm, '"');
325 if (ecomm) {
326 ++ecomm;
327 str_len = ecomm - comm;
328 } else {
329 str_len = strlen(comm) + 1;
330 ecomm = "";
331 }
332 size_t prefix_len = estr - str;
333 if (prefix_len > LOGGER_ENTRY_MAX_PAYLOAD) {
334 prefix_len = LOGGER_ENTRY_MAX_PAYLOAD;
335 }
336 size_t suffix_len = strnlen(ecomm, LOGGER_ENTRY_MAX_PAYLOAD - prefix_len);
337 message_len =
338 str_len + prefix_len + suffix_len + denial_metadata.length() + 2;
339
340 if (main) { // begin scope for main buffer
341 char newstr[message_len];
342
343 *newstr = info ? ANDROID_LOG_INFO : ANDROID_LOG_WARN;
344 strlcpy(newstr + 1, comm, str_len);
345 strncpy(newstr + 1 + str_len, str, prefix_len);
346 strncpy(newstr + 1 + str_len + prefix_len, ecomm, suffix_len);
347 strncpy(newstr + 1 + str_len + prefix_len + suffix_len,
348 denial_metadata.c_str(), denial_metadata.length());
349
350 rc = logbuf->log(
351 LOG_ID_MAIN, now, uid, pid, tid, newstr,
352 (message_len <= UINT16_MAX) ? (uint16_t)message_len : UINT16_MAX);
353
354 if (rc >= 0) {
355 notify |= 1 << LOG_ID_MAIN;
356 }
357 // end scope for main buffer
358 }
359
360 free(const_cast<char*>(commfree));
361 free(str);
362
363 if (notify) {
364 reader->notifyNewLog(notify);
365 if (rc < 0) {
366 rc = message_len;
367 }
368 }
369
370 return rc;
371 }
372
log(char * buf,size_t len)373 int LogAudit::log(char* buf, size_t len) {
374 char* audit = strstr(buf, " audit(");
375 if (!audit || (audit >= &buf[len])) {
376 return 0;
377 }
378
379 *audit = '\0';
380
381 int rc;
382 char* type = strstr(buf, "type=");
383 if (type && (type < &buf[len])) {
384 rc = logPrint("%s %s", type, audit + 1);
385 } else {
386 rc = logPrint("%s", audit + 1);
387 }
388 *audit = ' ';
389 return rc;
390 }
391
getLogSocket()392 int LogAudit::getLogSocket() {
393 int fd = audit_open();
394 if (fd < 0) {
395 return fd;
396 }
397 if (audit_setup(fd, getpid()) < 0) {
398 audit_close(fd);
399 fd = -1;
400 }
401 return fd;
402 }
403