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 "LogAudit.h"
18
19 #include <ctype.h>
20 #include <endian.h>
21 #include <errno.h>
22 #include <limits.h>
23 #include <stdarg.h>
24 #include <stdint.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <sys/prctl.h>
28 #include <sys/uio.h>
29 #include <syslog.h>
30
31 #include <android-base/file.h>
32 #include <android-base/logging.h>
33 #include <android-base/macros.h>
34 #include <android-base/properties.h>
35 #include <android-base/strings.h>
36 #include <private/android_filesystem_config.h>
37 #include <private/android_logger.h>
38
39 #include "LogKlog.h"
40 #include "LogUtils.h"
41 #include "libaudit.h"
42
43 using namespace std::string_literals;
44
45 using android::base::GetBoolProperty;
46
47 #define KMSG_PRIORITY(PRI) \
48 '<', '0' + LOG_MAKEPRI(LOG_AUTH, LOG_PRI(PRI)) / 10, \
49 '0' + LOG_MAKEPRI(LOG_AUTH, LOG_PRI(PRI)) % 10, '>'
50
LogAudit(LogBuffer * buf,int fdDmesg,LogStatistics * stats)51 LogAudit::LogAudit(LogBuffer* buf, int fdDmesg, LogStatistics* stats)
52 : SocketListener(getLogSocket(), false),
53 logbuf(buf),
54 fdDmesg(fdDmesg),
55 main(GetBoolProperty("ro.logd.auditd.main", true)),
56 events(GetBoolProperty("ro.logd.auditd.events", true)),
57 initialized(false),
58 stats_(stats) {
59 static const char auditd_message[] = { KMSG_PRIORITY(LOG_INFO),
60 'l',
61 'o',
62 'g',
63 'd',
64 '.',
65 'a',
66 'u',
67 'd',
68 'i',
69 't',
70 'd',
71 ':',
72 ' ',
73 's',
74 't',
75 'a',
76 'r',
77 't',
78 '\n' };
79 write(fdDmesg, auditd_message, sizeof(auditd_message));
80 }
81
onDataAvailable(SocketClient * cli)82 bool LogAudit::onDataAvailable(SocketClient* cli) {
83 if (!initialized) {
84 prctl(PR_SET_NAME, "logd.auditd");
85 initialized = true;
86 }
87
88 struct audit_message rep;
89
90 rep.nlh.nlmsg_type = 0;
91 rep.nlh.nlmsg_len = 0;
92 rep.data[0] = '\0';
93
94 if (audit_get_reply(cli->getSocket(), &rep, GET_REPLY_BLOCKING, 0) < 0) {
95 SLOGE("Failed on audit_get_reply with error: %s", strerror(errno));
96 return false;
97 }
98
99 logPrint("type=%d %.*s", rep.nlh.nlmsg_type, rep.nlh.nlmsg_len, rep.data);
100
101 return true;
102 }
103
hasMetadata(char * str,int str_len)104 static inline bool hasMetadata(char* str, int str_len) {
105 // need to check and see if str already contains bug metadata from
106 // possibility of stuttering if log audit crashes and then reloads kernel
107 // messages. Kernel denials that contain metadata will either end in
108 // "b/[0-9]+$" or "b/[0-9]+ duplicate messages suppressed$" which will put
109 // a '/' character at either 9 or 39 indices away from the end of the str.
110 return str_len >= 39 &&
111 (str[str_len - 9] == '/' || str[str_len - 39] == '/');
112 }
113
populateDenialMap()114 static auto populateDenialMap() {
115 std::map<std::tuple<std::string, std::string, std::string>, std::string> denial_to_bug;
116 // Order matters. Only the first occurrence of a
117 // (scontext, tcontext, tclass) combination is recorded.
118 for (const auto& bug_map_file :
119 {"/system_ext/etc/selinux/bug_map"s, "/vendor/etc/selinux/selinux_denial_metadata"s,
120 "/system/etc/selinux/bug_map"s}) {
121 std::string file_contents;
122 if (!android::base::ReadFileToString(bug_map_file, &file_contents)) {
123 continue;
124 }
125 int errors = 0;
126 for (const auto& line : android::base::Split(file_contents, "\n")) {
127 const auto fields = android::base::Tokenize(line, " ");
128 if (fields.empty() || android::base::StartsWith(fields.front(), '#')) {
129 continue;
130 }
131 if (fields.size() == 4) {
132 const std::string& scontext = fields[0];
133 const std::string& tcontext = fields[1];
134 const std::string& tclass = fields[2];
135 const std::string& bug_num = fields[3];
136 const auto [it, success] =
137 denial_to_bug.try_emplace({scontext, tcontext, tclass}, bug_num);
138 if (!success) {
139 const auto& [key, value] = *it;
140 LOG(WARNING) << "Ignored bug_map definition in " << bug_map_file << ": '"
141 << line
142 << "', (scontext, tcontext, tclass) denial combination is already "
143 "tagged with bug metadata '"
144 << value << "'";
145 }
146 } else {
147 LOG(ERROR) << "Ignored ill-formed bug_map definition in " << bug_map_file << ": '"
148 << line << "'";
149 ++errors;
150 }
151 }
152 if (errors) {
153 LOG(ERROR) << "Loaded bug_map file with " << errors << " errors: " << bug_map_file;
154 } else {
155 LOG(INFO) << "Loaded bug_map file: " << bug_map_file;
156 }
157 }
158 return denial_to_bug;
159 }
160
denialParse(const std::string & denial,char terminator,const std::string & search_term)161 std::string LogAudit::denialParse(const std::string& denial, char terminator,
162 const std::string& search_term) {
163 size_t start_index = denial.find(search_term);
164 if (start_index != std::string::npos) {
165 start_index += search_term.length();
166 return denial.substr(
167 start_index, denial.find(terminator, start_index) - start_index);
168 }
169 return "";
170 }
171
auditParse(const std::string & string,uid_t uid)172 std::string LogAudit::auditParse(const std::string& string, uid_t uid) {
173 // Allocate a static map object to memoize the loaded bug_map files.
174 static auto denial_to_bug = populateDenialMap();
175
176 std::string result;
177 std::string scontext = denialParse(string, ':', "scontext=u:object_r:");
178 std::string tcontext = denialParse(string, ':', "tcontext=u:object_r:");
179 std::string tclass = denialParse(string, ' ', "tclass=");
180 if (scontext.empty()) {
181 scontext = denialParse(string, ':', "scontext=u:r:");
182 }
183 if (tcontext.empty()) {
184 tcontext = denialParse(string, ':', "tcontext=u:r:");
185 }
186 auto search = denial_to_bug.find({scontext, tcontext, tclass});
187 if (search != denial_to_bug.end()) {
188 result = " bug=" + search->second;
189 }
190
191 // Ensure the uid name is not null before passing it to the bug string.
192 if (uid >= AID_APP_START && uid <= AID_APP_END) {
193 char* uidname = android::uidToName(uid);
194 if (uidname) {
195 result.append(" app="s + uidname);
196 free(uidname);
197 }
198 }
199 return result;
200 }
201
logPrint(const char * fmt,...)202 int LogAudit::logPrint(const char* fmt, ...) {
203 if (fmt == nullptr) {
204 return -EINVAL;
205 }
206
207 va_list args;
208
209 char* str = nullptr;
210 va_start(args, fmt);
211 int rc = vasprintf(&str, fmt, args);
212 va_end(args);
213
214 if (rc < 0) {
215 return rc;
216 }
217 char* cp;
218 // Work around kernels missing
219 // https://github.com/torvalds/linux/commit/b8f89caafeb55fba75b74bea25adc4e4cd91be67
220 // Such kernels improperly add newlines inside audit messages.
221 while ((cp = strchr(str, '\n'))) {
222 *cp = ' ';
223 }
224
225 pid_t pid = getpid();
226 pid_t tid = gettid();
227 uid_t uid = AID_LOGD;
228 static const char pid_str[] = " pid=";
229 char* pidptr = strstr(str, pid_str);
230 if (pidptr && isdigit(pidptr[sizeof(pid_str) - 1])) {
231 cp = pidptr + sizeof(pid_str) - 1;
232 pid = 0;
233 while (isdigit(*cp)) {
234 pid = (pid * 10) + (*cp - '0');
235 ++cp;
236 }
237 tid = pid;
238 uid = stats_->PidToUid(pid);
239 memmove(pidptr, cp, strlen(cp) + 1);
240 }
241
242 bool info = strstr(str, " permissive=1") || strstr(str, " policy loaded ");
243 static std::string denial_metadata;
244 if ((fdDmesg >= 0) && initialized) {
245 struct iovec iov[4];
246 static const char log_info[] = { KMSG_PRIORITY(LOG_INFO) };
247 static const char log_warning[] = { KMSG_PRIORITY(LOG_WARNING) };
248 static const char newline[] = "\n";
249
250 denial_metadata = auditParse(str, uid);
251 iov[0].iov_base = info ? const_cast<char*>(log_info) : const_cast<char*>(log_warning);
252 iov[0].iov_len = info ? sizeof(log_info) : sizeof(log_warning);
253 iov[1].iov_base = str;
254 iov[1].iov_len = strlen(str);
255 iov[2].iov_base = const_cast<char*>(denial_metadata.c_str());
256 iov[2].iov_len = denial_metadata.length();
257 iov[3].iov_base = const_cast<char*>(newline);
258 iov[3].iov_len = strlen(newline);
259
260 writev(fdDmesg, iov, arraysize(iov));
261 }
262
263 if (!main && !events) {
264 free(str);
265 return 0;
266 }
267
268 log_time now(log_time::EPOCH);
269
270 static const char audit_str[] = " audit(";
271 char* timeptr = strstr(str, audit_str);
272 if (timeptr && ((cp = now.strptime(timeptr + sizeof(audit_str) - 1, "%s.%q"))) &&
273 (*cp == ':')) {
274 memcpy(timeptr + sizeof(audit_str) - 1, "0.0", 3);
275 memmove(timeptr + sizeof(audit_str) - 1 + 3, cp, strlen(cp) + 1);
276 } else {
277 now = log_time(CLOCK_REALTIME);
278 }
279
280 // log to events
281
282 size_t str_len = strnlen(str, LOGGER_ENTRY_MAX_PAYLOAD);
283 if (((fdDmesg < 0) || !initialized) && !hasMetadata(str, str_len))
284 denial_metadata = auditParse(str, uid);
285 str_len = (str_len + denial_metadata.length() <= LOGGER_ENTRY_MAX_PAYLOAD)
286 ? str_len + denial_metadata.length()
287 : LOGGER_ENTRY_MAX_PAYLOAD;
288 size_t message_len = str_len + sizeof(android_log_event_string_t);
289
290 unsigned int notify = 0;
291
292 if (events) { // begin scope for event buffer
293 uint32_t buffer[(message_len + sizeof(uint32_t) - 1) / sizeof(uint32_t)];
294
295 android_log_event_string_t* event =
296 reinterpret_cast<android_log_event_string_t*>(buffer);
297 event->header.tag = htole32(AUDITD_LOG_TAG);
298 event->type = EVENT_TYPE_STRING;
299 event->length = htole32(str_len);
300 memcpy(event->data, str, str_len - denial_metadata.length());
301 memcpy(event->data + str_len - denial_metadata.length(),
302 denial_metadata.c_str(), denial_metadata.length());
303
304 rc = logbuf->Log(LOG_ID_EVENTS, now, uid, pid, tid, reinterpret_cast<char*>(event),
305 (message_len <= UINT16_MAX) ? (uint16_t)message_len : UINT16_MAX);
306 if (rc >= 0) {
307 notify |= 1 << LOG_ID_EVENTS;
308 }
309 // end scope for event buffer
310 }
311
312 // log to main
313
314 static const char comm_str[] = " comm=\"";
315 const char* comm = strstr(str, comm_str);
316 const char* estr = str + strlen(str);
317 const char* commfree = nullptr;
318 if (comm) {
319 estr = comm;
320 comm += sizeof(comm_str) - 1;
321 } else if (pid == getpid()) {
322 pid = tid;
323 comm = "auditd";
324 } else {
325 comm = commfree = stats_->PidToName(pid);
326 if (!comm) {
327 comm = "unknown";
328 }
329 }
330
331 const char* ecomm = strchr(comm, '"');
332 if (ecomm) {
333 ++ecomm;
334 str_len = ecomm - comm;
335 } else {
336 str_len = strlen(comm) + 1;
337 ecomm = "";
338 }
339 size_t prefix_len = estr - str;
340 if (prefix_len > LOGGER_ENTRY_MAX_PAYLOAD) {
341 prefix_len = LOGGER_ENTRY_MAX_PAYLOAD;
342 }
343 size_t suffix_len = strnlen(ecomm, LOGGER_ENTRY_MAX_PAYLOAD - prefix_len);
344 message_len =
345 str_len + prefix_len + suffix_len + denial_metadata.length() + 2;
346
347 if (main) { // begin scope for main buffer
348 char newstr[message_len];
349
350 *newstr = info ? ANDROID_LOG_INFO : ANDROID_LOG_WARN;
351 strlcpy(newstr + 1, comm, str_len);
352 strncpy(newstr + 1 + str_len, str, prefix_len);
353 strncpy(newstr + 1 + str_len + prefix_len, ecomm, suffix_len);
354 strncpy(newstr + 1 + str_len + prefix_len + suffix_len,
355 denial_metadata.c_str(), denial_metadata.length());
356
357 rc = logbuf->Log(LOG_ID_MAIN, now, uid, pid, tid, newstr,
358 (message_len <= UINT16_MAX) ? (uint16_t)message_len : UINT16_MAX);
359
360 if (rc >= 0) {
361 notify |= 1 << LOG_ID_MAIN;
362 }
363 // end scope for main buffer
364 }
365
366 free(const_cast<char*>(commfree));
367 free(str);
368
369 if (notify) {
370 if (rc < 0) {
371 rc = message_len;
372 }
373 }
374
375 return rc;
376 }
377
log(char * buf,size_t len)378 int LogAudit::log(char* buf, size_t len) {
379 char* audit = strstr(buf, " audit(");
380 if (!audit || (audit >= &buf[len])) {
381 return 0;
382 }
383
384 *audit = '\0';
385
386 int rc;
387 char* type = strstr(buf, "type=");
388 if (type && (type < &buf[len])) {
389 rc = logPrint("%s %s", type, audit + 1);
390 } else {
391 rc = logPrint("%s", audit + 1);
392 }
393 *audit = ' ';
394 return rc;
395 }
396
getLogSocket()397 int LogAudit::getLogSocket() {
398 int fd = audit_open();
399 if (fd < 0) {
400 return fd;
401 }
402 if (audit_setup(fd, getpid()) < 0) {
403 audit_close(fd);
404 fd = -1;
405 }
406 return fd;
407 }
408