1 /*
2 * Copyright (C) 2018 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 #define DEBUG false // STOPSHIP if true
17 #include "Log.h"
18
19 #include <ctype.h>
20 #include <limits.h>
21 #include <stdio.h>
22 #include <sys/cdefs.h>
23 #include <sys/prctl.h>
24 #include <sys/socket.h>
25 #include <sys/types.h>
26 #include <sys/un.h>
27 #include <unistd.h>
28
29 #include <cutils/sockets.h>
30 #include <private/android_filesystem_config.h>
31 #include <private/android_logger.h>
32 #include <unordered_map>
33
34 #include "StatsSocketListener.h"
35 #include "guardrail/StatsdStats.h"
36 #include "stats_log_util.h"
37
38 namespace android {
39 namespace os {
40 namespace statsd {
41
42 static const int kLogMsgHeaderSize = 28;
43
StatsSocketListener(const sp<LogListener> & listener)44 StatsSocketListener::StatsSocketListener(const sp<LogListener>& listener)
45 : SocketListener(getLogSocket(), false /*start listen*/), mListener(listener) {
46 }
47
~StatsSocketListener()48 StatsSocketListener::~StatsSocketListener() {
49 }
50
onDataAvailable(SocketClient * cli)51 bool StatsSocketListener::onDataAvailable(SocketClient* cli) {
52 static bool name_set;
53 if (!name_set) {
54 prctl(PR_SET_NAME, "statsd.writer");
55 name_set = true;
56 }
57
58 // + 1 to ensure null terminator if MAX_PAYLOAD buffer is received
59 char buffer[sizeof_log_id_t + sizeof(uint16_t) + sizeof(log_time) + LOGGER_ENTRY_MAX_PAYLOAD +
60 1];
61 struct iovec iov = {buffer, sizeof(buffer) - 1};
62
63 alignas(4) char control[CMSG_SPACE(sizeof(struct ucred))];
64 struct msghdr hdr = {
65 NULL, 0, &iov, 1, control, sizeof(control), 0,
66 };
67
68 int socket = cli->getSocket();
69
70 // To clear the entire buffer is secure/safe, but this contributes to 1.68%
71 // overhead under logging load. We are safe because we check counts, but
72 // still need to clear null terminator
73 // memset(buffer, 0, sizeof(buffer));
74 ssize_t n = recvmsg(socket, &hdr, 0);
75 if (n <= (ssize_t)(sizeof(android_log_header_t))) {
76 return false;
77 }
78
79 buffer[n] = 0;
80
81 struct ucred* cred = NULL;
82
83 struct cmsghdr* cmsg = CMSG_FIRSTHDR(&hdr);
84 while (cmsg != NULL) {
85 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_CREDENTIALS) {
86 cred = (struct ucred*)CMSG_DATA(cmsg);
87 break;
88 }
89 cmsg = CMSG_NXTHDR(&hdr, cmsg);
90 }
91
92 struct ucred fake_cred;
93 if (cred == NULL) {
94 cred = &fake_cred;
95 cred->pid = 0;
96 cred->uid = DEFAULT_OVERFLOWUID;
97 }
98
99 char* ptr = ((char*)buffer) + sizeof(android_log_header_t);
100 n -= sizeof(android_log_header_t);
101
102 log_msg msg;
103
104 msg.entry.len = n;
105 msg.entry.hdr_size = kLogMsgHeaderSize;
106 msg.entry.sec = time(nullptr);
107 msg.entry.pid = cred->pid;
108 msg.entry.uid = cred->uid;
109
110 memcpy(msg.buf + kLogMsgHeaderSize, ptr, n + 1);
111 LogEvent event(msg);
112
113 // Call the listener
114 mListener->OnLogEvent(&event, false /*reconnected, N/A in statsd socket*/);
115
116 return true;
117 }
118
getLogSocket()119 int StatsSocketListener::getLogSocket() {
120 static const char socketName[] = "statsdw";
121 int sock = android_get_control_socket(socketName);
122
123 if (sock < 0) { // statsd started up in init.sh
124 sock = socket_local_server(socketName, ANDROID_SOCKET_NAMESPACE_RESERVED, SOCK_DGRAM);
125
126 int on = 1;
127 if (setsockopt(sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on))) {
128 return -1;
129 }
130 }
131 return sock;
132 }
133
134 } // namespace statsd
135 } // namespace os
136 } // namespace android
137