361 lines
9.7 KiB
C++
361 lines
9.7 KiB
C++
/*
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* Copyright (C) 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <ctype.h>
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#include <endian.h>
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#include <errno.h>
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#include <limits.h>
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#include <stdarg.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/prctl.h>
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#include <sys/uio.h>
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#include <syslog.h>
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#include <string>
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#include <cutils/properties.h>
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#include <log/logger.h>
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#include <private/android_filesystem_config.h>
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#include <private/android_logger.h>
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#include "libaudit.h"
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#include "LogAudit.h"
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#include "LogBuffer.h"
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#include "LogKlog.h"
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#include "LogReader.h"
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#ifndef AUDITD_ENFORCE_INTEGRITY
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#define AUDITD_ENFORCE_INTEGRITY false
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#endif
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#define KMSG_PRIORITY(PRI) \
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'<', \
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'0' + LOG_MAKEPRI(LOG_AUTH, LOG_PRI(PRI)) / 10, \
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'0' + LOG_MAKEPRI(LOG_AUTH, LOG_PRI(PRI)) % 10, \
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'>'
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LogAudit::LogAudit(LogBuffer *buf, LogReader *reader, int fdDmesg) :
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SocketListener(getLogSocket(), false),
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logbuf(buf),
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reader(reader),
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fdDmesg(fdDmesg),
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policyLoaded(false),
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rebootToSafeMode(false),
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initialized(false) {
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logToDmesg("start");
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}
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bool LogAudit::onDataAvailable(SocketClient *cli) {
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if (!initialized) {
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prctl(PR_SET_NAME, "logd.auditd");
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initialized = true;
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}
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struct audit_message rep;
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rep.nlh.nlmsg_type = 0;
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rep.nlh.nlmsg_len = 0;
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rep.data[0] = '\0';
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if (audit_get_reply(cli->getSocket(), &rep, GET_REPLY_BLOCKING, 0) < 0) {
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SLOGE("Failed on audit_get_reply with error: %s", strerror(errno));
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return false;
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}
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logPrint("type=%d %.*s",
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rep.nlh.nlmsg_type, rep.nlh.nlmsg_len, rep.data);
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return true;
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}
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void LogAudit::logToDmesg(const std::string& str)
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{
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static const char prefix[] = { KMSG_PRIORITY(LOG_INFO),
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'l', 'o', 'g', 'd', '.', 'a', 'u', 'd', 'i', 't', 'd', ':',
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' ', '\0' };
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std::string message = prefix + str + "\n";
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write(fdDmesg, message.c_str(), message.length());
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}
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std::string LogAudit::getProperty(const std::string& name)
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{
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char value[PROP_VALUE_MAX] = {0};
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property_get(name.c_str(), value, "");
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return value;
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}
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void LogAudit::enforceIntegrity() {
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static bool loggedOnce;
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bool once = loggedOnce;
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loggedOnce = true;
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if (!AUDITD_ENFORCE_INTEGRITY) {
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if (!once) {
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logToDmesg("integrity enforcement suppressed; not rebooting");
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}
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} else if (rebootToSafeMode) {
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if (getProperty("persist.sys.safemode") == "1") {
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if (!once) {
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logToDmesg("integrity enforcement suppressed; in safe mode");
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}
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return;
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}
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logToDmesg("enforcing integrity; rebooting to safe mode");
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property_set("persist.sys.safemode", "1");
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std::string buildDate = getProperty("ro.build.date.utc");
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if (!buildDate.empty()) {
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property_set("persist.sys.audit_safemode", buildDate.c_str());
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}
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property_set("sys.powerctl", "reboot");
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} else {
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logToDmesg("enforcing integrity: rebooting to recovery");
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property_set("sys.powerctl", "reboot,recovery");
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}
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}
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int LogAudit::logPrint(const char *fmt, ...) {
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if (fmt == NULL) {
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return -EINVAL;
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}
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va_list args;
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char *str = NULL;
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va_start(args, fmt);
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int rc = vasprintf(&str, fmt, args);
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va_end(args);
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if (rc < 0) {
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return rc;
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}
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char *cp;
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while ((cp = strstr(str, " "))) {
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memmove(cp, cp + 1, strlen(cp + 1) + 1);
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}
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bool loaded = strstr(str, " policy loaded ");
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if (loaded) {
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if (policyLoaded) {
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// SELinux policy changes are not allowed
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enforceIntegrity();
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} else {
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logToDmesg("policy loaded");
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policyLoaded = true;
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}
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}
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// Note: The audit log can include untrusted strings, but those containing
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// "a control character, unprintable character, double quote mark, or a
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// space" are hex encoded. The space character before the search term is
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// therefore needed to prevent denial of service. Do not remove the space.
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bool permissive = strstr(str, " enforcing=0") ||
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strstr(str, " permissive=1");
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if (permissive) {
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// SELinux in permissive mode is not allowed
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enforceIntegrity();
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}
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bool info = loaded || permissive;
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if ((fdDmesg >= 0) && initialized) {
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struct iovec iov[3];
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static const char log_info[] = { KMSG_PRIORITY(LOG_INFO) };
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static const char log_warning[] = { KMSG_PRIORITY(LOG_WARNING) };
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iov[0].iov_base = info ? const_cast<char *>(log_info)
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: const_cast<char *>(log_warning);
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iov[0].iov_len = info ? sizeof(log_info) : sizeof(log_warning);
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iov[1].iov_base = str;
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iov[1].iov_len = strlen(str);
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iov[2].iov_base = const_cast<char *>("\n");
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iov[2].iov_len = 1;
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writev(fdDmesg, iov, sizeof(iov) / sizeof(iov[0]));
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}
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pid_t pid = getpid();
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pid_t tid = gettid();
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uid_t uid = AID_LOGD;
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log_time now;
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static const char audit_str[] = " audit(";
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char *timeptr = strstr(str, audit_str);
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if (timeptr
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&& ((cp = now.strptime(timeptr + sizeof(audit_str) - 1, "%s.%q")))
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&& (*cp == ':')) {
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memcpy(timeptr + sizeof(audit_str) - 1, "0.0", 3);
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memmove(timeptr + sizeof(audit_str) - 1 + 3, cp, strlen(cp) + 1);
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if (!isMonotonic()) {
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if (android::isMonotonic(now)) {
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LogKlog::convertMonotonicToReal(now);
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}
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} else {
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if (!android::isMonotonic(now)) {
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LogKlog::convertRealToMonotonic(now);
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}
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}
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} else if (isMonotonic()) {
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now = log_time(CLOCK_MONOTONIC);
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} else {
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now = log_time(CLOCK_REALTIME);
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}
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static const char pid_str[] = " pid=";
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char *pidptr = strstr(str, pid_str);
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if (pidptr && isdigit(pidptr[sizeof(pid_str) - 1])) {
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cp = pidptr + sizeof(pid_str) - 1;
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pid = 0;
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while (isdigit(*cp)) {
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pid = (pid * 10) + (*cp - '0');
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++cp;
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}
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tid = pid;
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logbuf->lock();
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uid = logbuf->pidToUid(pid);
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logbuf->unlock();
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memmove(pidptr, cp, strlen(cp) + 1);
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}
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// log to events
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size_t l = strnlen(str, LOGGER_ENTRY_MAX_PAYLOAD);
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size_t n = l + sizeof(android_log_event_string_t);
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bool notify = false;
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{ // begin scope for event buffer
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uint32_t buffer[(n + sizeof(uint32_t) - 1) / sizeof(uint32_t)];
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android_log_event_string_t *event
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= reinterpret_cast<android_log_event_string_t *>(buffer);
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event->header.tag = htole32(AUDITD_LOG_TAG);
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event->type = EVENT_TYPE_STRING;
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event->length = htole32(l);
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memcpy(event->data, str, l);
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rc = logbuf->log(LOG_ID_EVENTS, now, uid, pid, tid,
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reinterpret_cast<char *>(event),
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(n <= USHRT_MAX) ? (unsigned short) n : USHRT_MAX);
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if (rc >= 0) {
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notify = true;
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}
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// end scope for event buffer
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}
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// log to main
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static const char comm_str[] = " comm=\"";
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const char *comm = strstr(str, comm_str);
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const char *estr = str + strlen(str);
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const char *commfree = NULL;
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if (comm) {
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estr = comm;
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comm += sizeof(comm_str) - 1;
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} else if (pid == getpid()) {
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pid = tid;
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comm = "auditd";
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} else {
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logbuf->lock();
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comm = commfree = logbuf->pidToName(pid);
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logbuf->unlock();
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if (!comm) {
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comm = "unknown";
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}
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}
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const char *ecomm = strchr(comm, '"');
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if (ecomm) {
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++ecomm;
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l = ecomm - comm;
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} else {
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l = strlen(comm) + 1;
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ecomm = "";
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}
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size_t b = estr - str;
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if (b > LOGGER_ENTRY_MAX_PAYLOAD) {
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b = LOGGER_ENTRY_MAX_PAYLOAD;
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}
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size_t e = strnlen(ecomm, LOGGER_ENTRY_MAX_PAYLOAD - b);
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n = b + e + l + 2;
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{ // begin scope for main buffer
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char newstr[n];
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*newstr = info ? ANDROID_LOG_INFO : ANDROID_LOG_WARN;
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strlcpy(newstr + 1, comm, l);
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strncpy(newstr + 1 + l, str, b);
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strncpy(newstr + 1 + l + b, ecomm, e);
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rc = logbuf->log(LOG_ID_MAIN, now, uid, pid, tid, newstr,
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(n <= USHRT_MAX) ? (unsigned short) n : USHRT_MAX);
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if (rc >= 0) {
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notify = true;
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}
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// end scope for main buffer
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}
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free(const_cast<char *>(commfree));
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free(str);
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if (notify) {
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reader->notifyNewLog();
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if (rc < 0) {
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rc = n;
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}
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}
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return rc;
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}
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int LogAudit::log(char *buf, size_t len) {
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char *audit = strstr(buf, " audit(");
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if (!audit || (audit >= &buf[len])) {
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return 0;
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}
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*audit = '\0';
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int rc;
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char *type = strstr(buf, "type=");
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if (type && (type < &buf[len])) {
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rc = logPrint("%s %s", type, audit + 1);
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} else {
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rc = logPrint("%s", audit + 1);
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}
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*audit = ' ';
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return rc;
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}
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int LogAudit::getLogSocket() {
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int fd = audit_open();
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if (fd < 0) {
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return fd;
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}
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if (audit_setup(fd, getpid()) < 0) {
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audit_close(fd);
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fd = -1;
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}
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return fd;
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}
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