1/* 2 * Copyright (C) 2012-2014 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 <limits.h> 18#include <sys/prctl.h> 19#include <sys/socket.h> 20#include <sys/types.h> 21#include <sys/un.h> 22#include <unistd.h> 23 24#include <cutils/sockets.h> 25#include <log/logger.h> 26 27#include "LogListener.h" 28 29LogListener::LogListener(LogBuffer *buf, LogReader *reader) 30 : SocketListener(getLogSocket(), false) 31 , logbuf(buf) 32 , reader(reader) 33{ } 34 35bool LogListener::onDataAvailable(SocketClient *cli) { 36 prctl(PR_SET_NAME, "logd.writer"); 37 38 char buffer[sizeof_log_id_t + sizeof(uint16_t) + sizeof(log_time) 39 + LOGGER_ENTRY_MAX_PAYLOAD]; 40 struct iovec iov = { buffer, sizeof(buffer) }; 41 memset(buffer, 0, sizeof(buffer)); 42 43 char control[CMSG_SPACE(sizeof(struct ucred))]; 44 struct msghdr hdr = { 45 NULL, 46 0, 47 &iov, 48 1, 49 control, 50 sizeof(control), 51 0, 52 }; 53 54 int socket = cli->getSocket(); 55 56 ssize_t n = recvmsg(socket, &hdr, 0); 57 if (n <= (ssize_t)(sizeof_log_id_t + sizeof(uint16_t) + sizeof(log_time))) { 58 return false; 59 } 60 61 struct ucred *cred = NULL; 62 63 struct cmsghdr *cmsg = CMSG_FIRSTHDR(&hdr); 64 while (cmsg != NULL) { 65 if (cmsg->cmsg_level == SOL_SOCKET 66 && cmsg->cmsg_type == SCM_CREDENTIALS) { 67 cred = (struct ucred *)CMSG_DATA(cmsg); 68 break; 69 } 70 cmsg = CMSG_NXTHDR(&hdr, cmsg); 71 } 72 73 if (cred == NULL) { 74 return false; 75 } 76 77 if (cred->uid == getuid()) { 78 // ignore log messages we send to ourself. 79 // Such log messages are often generated by libraries we depend on 80 // which use standard Android logging. 81 return false; 82 } 83 84 // First log element is always log_id. 85 log_id_t log_id = (log_id_t) *((typeof_log_id_t *) buffer); 86 if (log_id < 0 || log_id >= LOG_ID_MAX) { 87 return false; 88 } 89 char *msg = ((char *)buffer) + sizeof_log_id_t; 90 n -= sizeof_log_id_t; 91 92 // second element is the thread id of the caller 93 pid_t tid = (pid_t) *((uint16_t *) msg); 94 msg += sizeof(uint16_t); 95 n -= sizeof(uint16_t); 96 97 // third element is the realtime at point of caller 98 log_time realtime(msg); 99 msg += sizeof(log_time); 100 n -= sizeof(log_time); 101 102 // NB: hdr.msg_flags & MSG_TRUNC is not tested, silently passing a 103 // truncated message to the logs. 104 105 logbuf->log(log_id, realtime, cred->uid, cred->pid, tid, msg, 106 ((size_t) n <= USHRT_MAX) ? (unsigned short) n : USHRT_MAX); 107 reader->notifyNewLog(); 108 109 return true; 110} 111 112int LogListener::getLogSocket() { 113 static const char socketName[] = "logdw"; 114 int sock = android_get_control_socket(socketName); 115 116 if (sock < 0) { 117 sock = socket_local_server(socketName, 118 ANDROID_SOCKET_NAMESPACE_RESERVED, 119 SOCK_DGRAM); 120 } 121 122 int on = 1; 123 if (setsockopt(sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0) { 124 return -1; 125 } 126 return sock; 127} 128