| /* |
| * Copyright (C) 2012-2013 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include <dirent.h> |
| #include <errno.h> |
| #include <fcntl.h> |
| #include <poll.h> |
| #include <sched.h> |
| #include <semaphore.h> |
| #include <signal.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <sys/capability.h> |
| #include <sys/klog.h> |
| #include <sys/prctl.h> |
| #include <sys/resource.h> |
| #include <sys/stat.h> |
| #include <sys/types.h> |
| #include <syslog.h> |
| #include <unistd.h> |
| |
| #include <memory> |
| |
| #include <cutils/properties.h> |
| #include <cutils/sched_policy.h> |
| #include <cutils/sockets.h> |
| #include <log/event_tag_map.h> |
| #include <private/android_filesystem_config.h> |
| #include <utils/threads.h> |
| |
| #include "CommandListener.h" |
| #include "LogBuffer.h" |
| #include "LogListener.h" |
| #include "LogAudit.h" |
| #include "LogKlog.h" |
| |
| #define KMSG_PRIORITY(PRI) \ |
| '<', \ |
| '0' + LOG_MAKEPRI(LOG_DAEMON, LOG_PRI(PRI)) / 10, \ |
| '0' + LOG_MAKEPRI(LOG_DAEMON, LOG_PRI(PRI)) % 10, \ |
| '>' |
| |
| // |
| // The service is designed to be run by init, it does not respond well |
| // to starting up manually. When starting up manually the sockets will |
| // fail to open typically for one of the following reasons: |
| // EADDRINUSE if logger is running. |
| // EACCESS if started without precautions (below) |
| // |
| // Here is a cookbook procedure for starting up logd manually assuming |
| // init is out of the way, pedantically all permissions and selinux |
| // security is put back in place: |
| // |
| // setenforce 0 |
| // rm /dev/socket/logd* |
| // chmod 777 /dev/socket |
| // # here is where you would attach the debugger or valgrind for example |
| // runcon u:r:logd:s0 /system/bin/logd </dev/null >/dev/null 2>&1 & |
| // sleep 1 |
| // chmod 755 /dev/socket |
| // chown logd.logd /dev/socket/logd* |
| // restorecon /dev/socket/logd* |
| // setenforce 1 |
| // |
| // If minimalism prevails, typical for debugging and security is not a concern: |
| // |
| // setenforce 0 |
| // chmod 777 /dev/socket |
| // logd |
| // |
| |
| static int drop_privs() { |
| struct sched_param param; |
| memset(¶m, 0, sizeof(param)); |
| |
| if (set_sched_policy(0, SP_BACKGROUND) < 0) { |
| return -1; |
| } |
| |
| if (sched_setscheduler((pid_t) 0, SCHED_BATCH, ¶m) < 0) { |
| return -1; |
| } |
| |
| if (setpriority(PRIO_PROCESS, 0, ANDROID_PRIORITY_BACKGROUND) < 0) { |
| return -1; |
| } |
| |
| if (prctl(PR_SET_KEEPCAPS, 1) < 0) { |
| return -1; |
| } |
| |
| if (setgroups(0, NULL) == -1) { |
| return -1; |
| } |
| |
| if (setgid(AID_LOGD) != 0) { |
| return -1; |
| } |
| |
| if (setuid(AID_LOGD) != 0) { |
| return -1; |
| } |
| |
| struct __user_cap_header_struct capheader; |
| struct __user_cap_data_struct capdata[2]; |
| memset(&capheader, 0, sizeof(capheader)); |
| memset(&capdata, 0, sizeof(capdata)); |
| capheader.version = _LINUX_CAPABILITY_VERSION_3; |
| capheader.pid = 0; |
| |
| capdata[CAP_TO_INDEX(CAP_SYSLOG)].permitted = CAP_TO_MASK(CAP_SYSLOG); |
| capdata[CAP_TO_INDEX(CAP_AUDIT_CONTROL)].permitted |= CAP_TO_MASK(CAP_AUDIT_CONTROL); |
| |
| capdata[0].effective = capdata[0].permitted; |
| capdata[1].effective = capdata[1].permitted; |
| capdata[0].inheritable = 0; |
| capdata[1].inheritable = 0; |
| |
| if (capset(&capheader, &capdata[0]) < 0) { |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| // Property helper |
| static bool property_get_bool(const char *key, bool def) { |
| char property[PROPERTY_VALUE_MAX]; |
| property_get(key, property, ""); |
| |
| if (!strcasecmp(property, "true")) { |
| return true; |
| } |
| if (!strcasecmp(property, "false")) { |
| return false; |
| } |
| |
| return def; |
| } |
| |
| // Remove the static, and use this variable |
| // globally for debugging if necessary. eg: |
| // write(fdDmesg, "I am here\n", 10); |
| static int fdDmesg = -1; |
| |
| static sem_t uidName; |
| static uid_t uid; |
| static char *name; |
| |
| static sem_t reinit; |
| static bool reinit_running = false; |
| static LogBuffer *logBuf = NULL; |
| |
| static void *reinit_thread_start(void * /*obj*/) { |
| prctl(PR_SET_NAME, "logd.daemon"); |
| set_sched_policy(0, SP_BACKGROUND); |
| setpriority(PRIO_PROCESS, 0, ANDROID_PRIORITY_BACKGROUND); |
| |
| setgid(AID_SYSTEM); |
| setuid(AID_SYSTEM); |
| |
| while (reinit_running && !sem_wait(&reinit) && reinit_running) { |
| |
| // uidToName Privileged Worker |
| if (uid) { |
| name = NULL; |
| |
| FILE *fp = fopen("/data/system/packages.list", "r"); |
| if (fp) { |
| // This simple parser is sensitive to format changes in |
| // frameworks/base/services/core/java/com/android/server/pm/Settings.java |
| // A dependency note has been added to that file to correct |
| // this parser. |
| |
| char *buffer = NULL; |
| size_t len; |
| while (getline(&buffer, &len, fp) > 0) { |
| char *userId = strchr(buffer, ' '); |
| if (!userId) { |
| continue; |
| } |
| *userId = '\0'; |
| unsigned long value = strtoul(userId + 1, NULL, 10); |
| if (value != uid) { |
| continue; |
| } |
| name = strdup(buffer); |
| break; |
| } |
| free(buffer); |
| fclose(fp); |
| } |
| uid = 0; |
| sem_post(&uidName); |
| continue; |
| } |
| |
| if (fdDmesg >= 0) { |
| static const char reinit_message[] = { KMSG_PRIORITY(LOG_INFO), |
| 'l', 'o', 'g', 'd', '.', 'd', 'a', 'e', 'm', 'o', 'n', ':', |
| ' ', 'r', 'e', 'i', 'n', 'i', 't', '\n' }; |
| write(fdDmesg, reinit_message, sizeof(reinit_message)); |
| } |
| |
| // Anything that reads persist.<property> |
| if (logBuf) { |
| logBuf->init(); |
| } |
| } |
| |
| return NULL; |
| } |
| |
| static sem_t sem_name; |
| |
| char *android::uidToName(uid_t u) { |
| if (!u || !reinit_running) { |
| return NULL; |
| } |
| |
| sem_wait(&sem_name); |
| |
| // Not multi-thread safe, we use sem_name to protect |
| uid = u; |
| |
| name = NULL; |
| sem_post(&reinit); |
| sem_wait(&uidName); |
| char *ret = name; |
| |
| sem_post(&sem_name); |
| |
| return ret; |
| } |
| |
| // Serves as a global method to trigger reinitialization |
| // and as a function that can be provided to signal(). |
| void reinit_signal_handler(int /*signal*/) { |
| sem_post(&reinit); |
| } |
| |
| // tagToName converts an events tag into a name |
| const char *android::tagToName(uint32_t tag) { |
| static const EventTagMap *map; |
| |
| if (!map) { |
| sem_wait(&sem_name); |
| if (!map) { |
| map = android_openEventTagMap(EVENT_TAG_MAP_FILE); |
| } |
| sem_post(&sem_name); |
| if (!map) { |
| return NULL; |
| } |
| } |
| return android_lookupEventTag(map, tag); |
| } |
| |
| static bool property_get_bool_svelte(const char *key) { |
| bool not_user; |
| { |
| char property[PROPERTY_VALUE_MAX]; |
| property_get("ro.build.type", property, ""); |
| not_user = !!strcmp(property, "user"); |
| } |
| return property_get_bool(key, not_user |
| && !property_get_bool("ro.config.low_ram", false)); |
| } |
| |
| static void readDmesg(LogAudit *al, LogKlog *kl) { |
| if (!al && !kl) { |
| return; |
| } |
| |
| int len = klogctl(KLOG_SIZE_BUFFER, NULL, 0); |
| if (len <= 0) { |
| return; |
| } |
| |
| len += 1024; // Margin for additional input race or trailing nul |
| std::unique_ptr<char []> buf(new char[len]); |
| |
| int rc = klogctl(KLOG_READ_ALL, buf.get(), len); |
| if (rc <= 0) { |
| return; |
| } |
| |
| if (rc < len) { |
| len = rc + 1; |
| } |
| buf[len - 1] = '\0'; |
| |
| if (kl) { |
| kl->synchronize(buf.get()); |
| } |
| |
| for (char *ptr = NULL, *tok = buf.get(); |
| (rc >= 0) && ((tok = log_strtok_r(tok, &ptr))); |
| tok = NULL) { |
| if (al) { |
| rc = al->log(tok); |
| } |
| if (kl) { |
| rc = kl->log(tok); |
| } |
| } |
| } |
| |
| // Foreground waits for exit of the main persistent threads |
| // that are started here. The threads are created to manage |
| // UNIX domain client sockets for writing, reading and |
| // controlling the user space logger, and for any additional |
| // logging plugins like auditd and restart control. Additional |
| // transitory per-client threads are created for each reader. |
| int main(int argc, char *argv[]) { |
| int fdPmesg = -1; |
| bool klogd = property_get_bool_svelte("logd.klogd"); |
| if (klogd) { |
| fdPmesg = open("/proc/kmsg", O_RDONLY | O_NDELAY); |
| } |
| fdDmesg = open("/dev/kmsg", O_WRONLY); |
| |
| // issue reinit command. KISS argument parsing. |
| if ((argc > 1) && argv[1] && !strcmp(argv[1], "--reinit")) { |
| int sock = TEMP_FAILURE_RETRY( |
| socket_local_client("logd", |
| ANDROID_SOCKET_NAMESPACE_RESERVED, |
| SOCK_STREAM)); |
| if (sock < 0) { |
| return -errno; |
| } |
| static const char reinit[] = "reinit"; |
| ssize_t ret = TEMP_FAILURE_RETRY(write(sock, reinit, sizeof(reinit))); |
| if (ret < 0) { |
| return -errno; |
| } |
| struct pollfd p; |
| memset(&p, 0, sizeof(p)); |
| p.fd = sock; |
| p.events = POLLIN; |
| ret = TEMP_FAILURE_RETRY(poll(&p, 1, 100)); |
| if (ret < 0) { |
| return -errno; |
| } |
| if ((ret == 0) || !(p.revents & POLLIN)) { |
| return -ETIME; |
| } |
| static const char success[] = "success"; |
| char buffer[sizeof(success) - 1]; |
| memset(buffer, 0, sizeof(buffer)); |
| ret = TEMP_FAILURE_RETRY(read(sock, buffer, sizeof(buffer))); |
| if (ret < 0) { |
| return -errno; |
| } |
| return strncmp(buffer, success, sizeof(success) - 1) != 0; |
| } |
| |
| // Reinit Thread |
| sem_init(&reinit, 0, 0); |
| sem_init(&uidName, 0, 0); |
| sem_init(&sem_name, 0, 1); |
| pthread_attr_t attr; |
| if (!pthread_attr_init(&attr)) { |
| struct sched_param param; |
| |
| memset(¶m, 0, sizeof(param)); |
| pthread_attr_setschedparam(&attr, ¶m); |
| pthread_attr_setschedpolicy(&attr, SCHED_BATCH); |
| if (!pthread_attr_setdetachstate(&attr, |
| PTHREAD_CREATE_DETACHED)) { |
| pthread_t thread; |
| reinit_running = true; |
| if (pthread_create(&thread, &attr, reinit_thread_start, NULL)) { |
| reinit_running = false; |
| } |
| } |
| pthread_attr_destroy(&attr); |
| } |
| |
| if (drop_privs() != 0) { |
| return -1; |
| } |
| |
| // Serves the purpose of managing the last logs times read on a |
| // socket connection, and as a reader lock on a range of log |
| // entries. |
| |
| LastLogTimes *times = new LastLogTimes(); |
| |
| // LogBuffer is the object which is responsible for holding all |
| // log entries. |
| |
| logBuf = new LogBuffer(times); |
| |
| signal(SIGHUP, reinit_signal_handler); |
| |
| if (property_get_bool_svelte("logd.statistics")) { |
| logBuf->enableStatistics(); |
| } |
| |
| // LogReader listens on /dev/socket/logdr. When a client |
| // connects, log entries in the LogBuffer are written to the client. |
| |
| LogReader *reader = new LogReader(logBuf); |
| if (reader->startListener()) { |
| exit(1); |
| } |
| |
| // LogListener listens on /dev/socket/logdw for client |
| // initiated log messages. New log entries are added to LogBuffer |
| // and LogReader is notified to send updates to connected clients. |
| |
| LogListener *swl = new LogListener(logBuf, reader); |
| // Backlog and /proc/sys/net/unix/max_dgram_qlen set to large value |
| if (swl->startListener(300)) { |
| exit(1); |
| } |
| |
| // Command listener listens on /dev/socket/logd for incoming logd |
| // administrative commands. |
| |
| CommandListener *cl = new CommandListener(logBuf, reader, swl); |
| if (cl->startListener()) { |
| exit(1); |
| } |
| |
| // LogAudit listens on NETLINK_AUDIT socket for selinux |
| // initiated log messages. New log entries are added to LogBuffer |
| // and LogReader is notified to send updates to connected clients. |
| |
| bool auditd = property_get_bool("logd.auditd", true); |
| |
| LogAudit *al = NULL; |
| if (auditd) { |
| bool dmesg = property_get_bool("logd.auditd.dmesg", true); |
| al = new LogAudit(logBuf, reader, dmesg ? fdDmesg : -1); |
| } |
| |
| LogKlog *kl = NULL; |
| if (klogd) { |
| kl = new LogKlog(logBuf, reader, fdDmesg, fdPmesg, al != NULL); |
| } |
| |
| readDmesg(al, kl); |
| |
| // failure is an option ... messages are in dmesg (required by standard) |
| |
| if (kl && kl->startListener()) { |
| delete kl; |
| } |
| |
| if (al && al->startListener()) { |
| delete al; |
| } |
| |
| TEMP_FAILURE_RETRY(pause()); |
| |
| exit(0); |
| } |
