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 while ((cp = strstr(str, " "))) {
226 memmove(cp, cp + 1, strlen(cp + 1) + 1);
227 }
228 pid_t pid = getpid();
229 pid_t tid = gettid();
230 uid_t uid = AID_LOGD;
231 static const char pid_str[] = " pid=";
232 char* pidptr = strstr(str, pid_str);
233 if (pidptr && isdigit(pidptr[sizeof(pid_str) - 1])) {
234 cp = pidptr + sizeof(pid_str) - 1;
235 pid = 0;
236 while (isdigit(*cp)) {
237 pid = (pid * 10) + (*cp - '0');
238 ++cp;
239 }
240 tid = pid;
241 uid = stats_->PidToUid(pid);
242 memmove(pidptr, cp, strlen(cp) + 1);
243 }
244
245 bool info = strstr(str, " permissive=1") || strstr(str, " policy loaded ");
246 static std::string denial_metadata;
247 if ((fdDmesg >= 0) && initialized) {
248 struct iovec iov[4];
249 static const char log_info[] = { KMSG_PRIORITY(LOG_INFO) };
250 static const char log_warning[] = { KMSG_PRIORITY(LOG_WARNING) };
251 static const char newline[] = "\n";
252
253 denial_metadata = auditParse(str, uid);
254 iov[0].iov_base = info ? const_cast<char*>(log_info) : 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*>(denial_metadata.c_str());
259 iov[2].iov_len = denial_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 if (!main && !events) {
267 free(str);
268 return 0;
269 }
270
271 log_time now(log_time::EPOCH);
272
273 static const char audit_str[] = " audit(";
274 char* timeptr = strstr(str, audit_str);
275 if (timeptr && ((cp = now.strptime(timeptr + sizeof(audit_str) - 1, "%s.%q"))) &&
276 (*cp == ':')) {
277 memcpy(timeptr + sizeof(audit_str) - 1, "0.0", 3);
278 memmove(timeptr + sizeof(audit_str) - 1 + 3, cp, strlen(cp) + 1);
279 } else {
280 now = log_time(CLOCK_REALTIME);
281 }
282
283 // log to events
284
285 size_t str_len = strnlen(str, LOGGER_ENTRY_MAX_PAYLOAD);
286 if (((fdDmesg < 0) || !initialized) && !hasMetadata(str, str_len))
287 denial_metadata = auditParse(str, uid);
288 str_len = (str_len + denial_metadata.length() <= LOGGER_ENTRY_MAX_PAYLOAD)
289 ? str_len + denial_metadata.length()
290 : LOGGER_ENTRY_MAX_PAYLOAD;
291 size_t message_len = str_len + sizeof(android_log_event_string_t);
292
293 unsigned int notify = 0;
294
295 if (events) { // begin scope for event buffer
296 uint32_t buffer[(message_len + sizeof(uint32_t) - 1) / sizeof(uint32_t)];
297
298 android_log_event_string_t* event =
299 reinterpret_cast<android_log_event_string_t*>(buffer);
300 event->header.tag = htole32(AUDITD_LOG_TAG);
301 event->type = EVENT_TYPE_STRING;
302 event->length = htole32(str_len);
303 memcpy(event->data, str, str_len - denial_metadata.length());
304 memcpy(event->data + str_len - denial_metadata.length(),
305 denial_metadata.c_str(), denial_metadata.length());
306
307 rc = logbuf->Log(LOG_ID_EVENTS, now, uid, pid, tid, reinterpret_cast<char*>(event),
308 (message_len <= UINT16_MAX) ? (uint16_t)message_len : UINT16_MAX);
309 if (rc >= 0) {
310 notify |= 1 << LOG_ID_EVENTS;
311 }
312 // end scope for event buffer
313 }
314
315 // log to main
316
317 static const char comm_str[] = " comm=\"";
318 const char* comm = strstr(str, comm_str);
319 const char* estr = str + strlen(str);
320 const char* commfree = nullptr;
321 if (comm) {
322 estr = comm;
323 comm += sizeof(comm_str) - 1;
324 } else if (pid == getpid()) {
325 pid = tid;
326 comm = "auditd";
327 } else {
328 comm = commfree = stats_->PidToName(pid);
329 if (!comm) {
330 comm = "unknown";
331 }
332 }
333
334 const char* ecomm = strchr(comm, '"');
335 if (ecomm) {
336 ++ecomm;
337 str_len = ecomm - comm;
338 } else {
339 str_len = strlen(comm) + 1;
340 ecomm = "";
341 }
342 size_t prefix_len = estr - str;
343 if (prefix_len > LOGGER_ENTRY_MAX_PAYLOAD) {
344 prefix_len = LOGGER_ENTRY_MAX_PAYLOAD;
345 }
346 size_t suffix_len = strnlen(ecomm, LOGGER_ENTRY_MAX_PAYLOAD - prefix_len);
347 message_len =
348 str_len + prefix_len + suffix_len + denial_metadata.length() + 2;
349
350 if (main) { // begin scope for main buffer
351 char newstr[message_len];
352
353 *newstr = info ? ANDROID_LOG_INFO : ANDROID_LOG_WARN;
354 strlcpy(newstr + 1, comm, str_len);
355 strncpy(newstr + 1 + str_len, str, prefix_len);
356 strncpy(newstr + 1 + str_len + prefix_len, ecomm, suffix_len);
357 strncpy(newstr + 1 + str_len + prefix_len + suffix_len,
358 denial_metadata.c_str(), denial_metadata.length());
359
360 rc = logbuf->Log(LOG_ID_MAIN, now, uid, pid, tid, newstr,
361 (message_len <= UINT16_MAX) ? (uint16_t)message_len : UINT16_MAX);
362
363 if (rc >= 0) {
364 notify |= 1 << LOG_ID_MAIN;
365 }
366 // end scope for main buffer
367 }
368
369 free(const_cast<char*>(commfree));
370 free(str);
371
372 if (notify) {
373 if (rc < 0) {
374 rc = message_len;
375 }
376 }
377
378 return rc;
379 }
380
log(char * buf,size_t len)381 int LogAudit::log(char* buf, size_t len) {
382 char* audit = strstr(buf, " audit(");
383 if (!audit || (audit >= &buf[len])) {
384 return 0;
385 }
386
387 *audit = '\0';
388
389 int rc;
390 char* type = strstr(buf, "type=");
391 if (type && (type < &buf[len])) {
392 rc = logPrint("%s %s", type, audit + 1);
393 } else {
394 rc = logPrint("%s", audit + 1);
395 }
396 *audit = ' ';
397 return rc;
398 }
399
getLogSocket()400 int LogAudit::getLogSocket() {
401 int fd = audit_open();
402 if (fd < 0) {
403 return fd;
404 }
405 if (audit_setup(fd, getpid()) < 0) {
406 audit_close(fd);
407 fd = -1;
408 }
409 return fd;
410 }
411