454 lines
13 KiB
C++
454 lines
13 KiB
C++
/*
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* Copyright (C) 2012-2013 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 <dirent.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <poll.h>
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#include <sched.h>
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#include <semaphore.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/capability.h>
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#include <sys/klog.h>
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#include <sys/prctl.h>
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#include <sys/resource.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <syslog.h>
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#include <unistd.h>
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#include <cutils/properties.h>
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#include <cutils/sched_policy.h>
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#include <cutils/sockets.h>
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#include <log/event_tag_map.h>
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#include <private/android_filesystem_config.h>
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#include <utils/threads.h>
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#include "CommandListener.h"
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#include "LogBuffer.h"
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#include "LogListener.h"
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#include "LogAudit.h"
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#include "LogKlog.h"
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#define KMSG_PRIORITY(PRI) \
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'<', \
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'0' + LOG_MAKEPRI(LOG_DAEMON, LOG_PRI(PRI)) / 10, \
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'0' + LOG_MAKEPRI(LOG_DAEMON, LOG_PRI(PRI)) % 10, \
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'>'
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//
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// The service is designed to be run by init, it does not respond well
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// to starting up manually. When starting up manually the sockets will
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// fail to open typically for one of the following reasons:
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// EADDRINUSE if logger is running.
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// EACCESS if started without precautions (below)
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//
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// Here is a cookbook procedure for starting up logd manually assuming
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// init is out of the way, pedantically all permissions and selinux
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// security is put back in place:
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//
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// setenforce 0
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// rm /dev/socket/logd*
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// chmod 777 /dev/socket
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// # here is where you would attach the debugger or valgrind for example
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// runcon u:r:logd:s0 /system/bin/logd </dev/null >/dev/null 2>&1 &
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// sleep 1
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// chmod 755 /dev/socket
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// chown logd.logd /dev/socket/logd*
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// restorecon /dev/socket/logd*
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// setenforce 1
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//
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// If minimalism prevails, typical for debugging and security is not a concern:
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//
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// setenforce 0
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// chmod 777 /dev/socket
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// logd
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//
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static int drop_privs() {
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struct sched_param param;
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memset(¶m, 0, sizeof(param));
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if (set_sched_policy(0, SP_BACKGROUND) < 0) {
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return -1;
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}
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if (sched_setscheduler((pid_t) 0, SCHED_BATCH, ¶m) < 0) {
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return -1;
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}
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if (setpriority(PRIO_PROCESS, 0, ANDROID_PRIORITY_BACKGROUND) < 0) {
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return -1;
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}
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if (prctl(PR_SET_KEEPCAPS, 1) < 0) {
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return -1;
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}
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if (setgid(AID_LOGD) != 0) {
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return -1;
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}
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if (setuid(AID_LOGD) != 0) {
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return -1;
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}
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struct __user_cap_header_struct capheader;
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struct __user_cap_data_struct capdata[2];
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memset(&capheader, 0, sizeof(capheader));
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memset(&capdata, 0, sizeof(capdata));
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capheader.version = _LINUX_CAPABILITY_VERSION_3;
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capheader.pid = 0;
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capdata[CAP_TO_INDEX(CAP_SYSLOG)].permitted = CAP_TO_MASK(CAP_SYSLOG);
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capdata[CAP_TO_INDEX(CAP_AUDIT_CONTROL)].permitted |= CAP_TO_MASK(CAP_AUDIT_CONTROL);
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capdata[0].effective = capdata[0].permitted;
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capdata[1].effective = capdata[1].permitted;
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capdata[0].inheritable = 0;
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capdata[1].inheritable = 0;
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if (capset(&capheader, &capdata[0]) < 0) {
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return -1;
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}
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return 0;
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}
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// Property helper
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static bool property_get_bool(const char *key, bool def) {
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char property[PROPERTY_VALUE_MAX];
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property_get(key, property, "");
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if (!strcasecmp(property, "true")) {
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return true;
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}
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if (!strcasecmp(property, "false")) {
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return false;
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}
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return def;
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}
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// Remove the static, and use this variable
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// globally for debugging if necessary. eg:
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// write(fdDmesg, "I am here\n", 10);
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static int fdDmesg = -1;
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static sem_t uidName;
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static uid_t uid;
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static char *name;
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static sem_t reinit;
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static bool reinit_running = false;
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static LogBuffer *logBuf = NULL;
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static void *reinit_thread_start(void * /*obj*/) {
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prctl(PR_SET_NAME, "logd.daemon");
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set_sched_policy(0, SP_BACKGROUND);
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setpriority(PRIO_PROCESS, 0, ANDROID_PRIORITY_BACKGROUND);
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setgid(AID_SYSTEM);
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setuid(AID_SYSTEM);
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while (reinit_running && !sem_wait(&reinit) && reinit_running) {
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// uidToName Privileged Worker
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if (uid) {
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name = NULL;
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FILE *fp = fopen("/data/system/packages.list", "r");
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if (fp) {
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// This simple parser is sensitive to format changes in
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// frameworks/base/services/core/java/com/android/server/pm/Settings.java
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// A dependency note has been added to that file to correct
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// this parser.
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char *buffer = NULL;
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size_t len;
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while (getline(&buffer, &len, fp) > 0) {
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char *userId = strchr(buffer, ' ');
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if (!userId) {
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continue;
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}
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*userId = '\0';
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unsigned long value = strtoul(userId + 1, NULL, 10);
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if (value != uid) {
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continue;
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}
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name = strdup(buffer);
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break;
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}
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free(buffer);
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fclose(fp);
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}
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uid = 0;
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sem_post(&uidName);
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continue;
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}
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if (fdDmesg >= 0) {
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static const char reinit_message[] = { KMSG_PRIORITY(LOG_INFO),
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'l', 'o', 'g', 'd', '.', 'd', 'a', 'e', 'm', 'o', 'n', ':',
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' ', 'r', 'e', 'i', 'n', 'i', 't', '\n' };
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write(fdDmesg, reinit_message, sizeof(reinit_message));
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}
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// Anything that reads persist.<property>
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if (logBuf) {
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logBuf->init();
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}
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}
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return NULL;
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}
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static sem_t sem_name;
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char *android::uidToName(uid_t u) {
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if (!u || !reinit_running) {
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return NULL;
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}
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sem_wait(&sem_name);
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// Not multi-thread safe, we use sem_name to protect
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uid = u;
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name = NULL;
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sem_post(&reinit);
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sem_wait(&uidName);
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char *ret = name;
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sem_post(&sem_name);
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return ret;
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}
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// Serves as a global method to trigger reinitialization
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// and as a function that can be provided to signal().
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void reinit_signal_handler(int /*signal*/) {
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sem_post(&reinit);
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}
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// tagToName converts an events tag into a name
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const char *android::tagToName(uint32_t tag) {
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static const EventTagMap *map;
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if (!map) {
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sem_wait(&sem_name);
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if (!map) {
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map = android_openEventTagMap(EVENT_TAG_MAP_FILE);
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}
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sem_post(&sem_name);
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if (!map) {
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return NULL;
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}
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}
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return android_lookupEventTag(map, tag);
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}
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static bool property_get_bool_svelte(const char *key) {
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bool not_user;
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{
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char property[PROPERTY_VALUE_MAX];
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property_get("ro.build.type", property, "");
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not_user = !!strcmp(property, "user");
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}
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return property_get_bool(key, not_user
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&& !property_get_bool("ro.config.low_ram", false));
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}
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// Foreground waits for exit of the main persistent threads
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// that are started here. The threads are created to manage
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// UNIX domain client sockets for writing, reading and
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// controlling the user space logger, and for any additional
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// logging plugins like auditd and restart control. Additional
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// transitory per-client threads are created for each reader.
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int main(int argc, char *argv[]) {
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int fdPmesg = -1;
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bool klogd = property_get_bool_svelte("logd.klogd");
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if (klogd) {
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fdPmesg = open("/proc/kmsg", O_RDONLY | O_NDELAY);
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}
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fdDmesg = open("/dev/kmsg", O_WRONLY);
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// issue reinit command. KISS argument parsing.
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if ((argc > 1) && argv[1] && !strcmp(argv[1], "--reinit")) {
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int sock = TEMP_FAILURE_RETRY(
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socket_local_client("logd",
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ANDROID_SOCKET_NAMESPACE_RESERVED,
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SOCK_STREAM));
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if (sock < 0) {
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return -errno;
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}
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static const char reinit[] = "reinit";
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ssize_t ret = TEMP_FAILURE_RETRY(write(sock, reinit, sizeof(reinit)));
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if (ret < 0) {
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return -errno;
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}
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struct pollfd p;
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memset(&p, 0, sizeof(p));
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p.fd = sock;
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p.events = POLLIN;
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ret = TEMP_FAILURE_RETRY(poll(&p, 1, 100));
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if (ret < 0) {
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return -errno;
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}
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if ((ret == 0) || !(p.revents & POLLIN)) {
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return -ETIME;
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}
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static const char success[] = "success";
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char buffer[sizeof(success) - 1];
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memset(buffer, 0, sizeof(buffer));
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ret = TEMP_FAILURE_RETRY(read(sock, buffer, sizeof(buffer)));
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if (ret < 0) {
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return -errno;
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}
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return strncmp(buffer, success, sizeof(success) - 1) != 0;
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}
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// Reinit Thread
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sem_init(&reinit, 0, 0);
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sem_init(&uidName, 0, 0);
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sem_init(&sem_name, 0, 1);
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pthread_attr_t attr;
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if (!pthread_attr_init(&attr)) {
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struct sched_param param;
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memset(¶m, 0, sizeof(param));
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pthread_attr_setschedparam(&attr, ¶m);
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pthread_attr_setschedpolicy(&attr, SCHED_BATCH);
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if (!pthread_attr_setdetachstate(&attr,
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PTHREAD_CREATE_DETACHED)) {
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pthread_t thread;
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reinit_running = true;
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if (pthread_create(&thread, &attr, reinit_thread_start, NULL)) {
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reinit_running = false;
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}
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}
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pthread_attr_destroy(&attr);
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}
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if (drop_privs() != 0) {
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return -1;
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}
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// Serves the purpose of managing the last logs times read on a
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// socket connection, and as a reader lock on a range of log
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// entries.
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LastLogTimes *times = new LastLogTimes();
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// LogBuffer is the object which is responsible for holding all
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// log entries.
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logBuf = new LogBuffer(times);
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signal(SIGHUP, reinit_signal_handler);
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if (property_get_bool_svelte("logd.statistics")) {
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logBuf->enableStatistics();
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}
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// LogReader listens on /dev/socket/logdr. When a client
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// connects, log entries in the LogBuffer are written to the client.
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LogReader *reader = new LogReader(logBuf);
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if (reader->startListener()) {
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exit(1);
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}
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// LogListener listens on /dev/socket/logdw for client
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// initiated log messages. New log entries are added to LogBuffer
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// and LogReader is notified to send updates to connected clients.
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LogListener *swl = new LogListener(logBuf, reader);
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// Backlog and /proc/sys/net/unix/max_dgram_qlen set to large value
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if (swl->startListener(300)) {
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exit(1);
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}
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// Command listener listens on /dev/socket/logd for incoming logd
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// administrative commands.
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CommandListener *cl = new CommandListener(logBuf, reader, swl);
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if (cl->startListener()) {
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exit(1);
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}
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// LogAudit listens on NETLINK_AUDIT socket for selinux
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// initiated log messages. New log entries are added to LogBuffer
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// and LogReader is notified to send updates to connected clients.
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bool auditd = property_get_bool("logd.auditd", true);
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LogAudit *al = NULL;
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if (auditd) {
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bool dmesg = property_get_bool("logd.auditd.dmesg", true);
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al = new LogAudit(logBuf, reader, dmesg ? fdDmesg : -1);
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}
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LogKlog *kl = NULL;
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if (klogd) {
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kl = new LogKlog(logBuf, reader, fdDmesg, fdPmesg, al != NULL);
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}
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if (al || kl) {
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int len = klogctl(KLOG_SIZE_BUFFER, NULL, 0);
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if (len > 0) {
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len++;
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char buf[len];
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int rc = klogctl(KLOG_READ_ALL, buf, len);
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buf[len - 1] = '\0';
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if ((rc >= 0) && kl) {
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kl->synchronize(buf);
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}
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for (char *ptr = NULL, *tok = buf;
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(rc >= 0) && ((tok = log_strtok_r(tok, &ptr)));
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tok = NULL) {
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if (al) {
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rc = al->log(tok);
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}
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if (kl) {
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rc = kl->log(tok);
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}
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}
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}
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// failure is an option ... messages are in dmesg (required by standard)
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if (kl && kl->startListener()) {
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delete kl;
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}
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if (al && al->startListener()) {
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delete al;
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}
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}
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TEMP_FAILURE_RETRY(pause());
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exit(0);
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}
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