1 /*
2  * Copyright (C) 2012-2013 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 <ctype.h>
18 #include <inttypes.h>
19 #include <poll.h>
20 #include <sched.h>
21 #include <sys/prctl.h>
22 #include <sys/socket.h>
23 #include <sys/types.h>
24 
25 #include <chrono>
26 
27 #include <android-base/logging.h>
28 #include <android-base/stringprintf.h>
29 #include <cutils/sockets.h>
30 #include <private/android_filesystem_config.h>
31 #include <private/android_logger.h>
32 
33 #include "LogBuffer.h"
34 #include "LogBufferElement.h"
35 #include "LogPermissions.h"
36 #include "LogReader.h"
37 #include "LogUtils.h"
38 #include "LogWriter.h"
39 
CanReadSecurityLogs(SocketClient * client)40 static bool CanReadSecurityLogs(SocketClient* client) {
41     return client->getUid() == AID_SYSTEM || client->getGid() == AID_SYSTEM;
42 }
43 
SocketClientToName(SocketClient * client)44 static std::string SocketClientToName(SocketClient* client) {
45     return android::base::StringPrintf("pid %d, fd %d", client->getPid(), client->getSocket());
46 }
47 
48 class SocketLogWriter : public LogWriter {
49   public:
SocketLogWriter(LogReader * reader,SocketClient * client,bool privileged)50     SocketLogWriter(LogReader* reader, SocketClient* client, bool privileged)
51         : LogWriter(client->getUid(), privileged), reader_(reader), client_(client) {}
52 
Write(const logger_entry & entry,const char * msg)53     bool Write(const logger_entry& entry, const char* msg) override {
54         struct iovec iovec[2];
55         iovec[0].iov_base = const_cast<logger_entry*>(&entry);
56         iovec[0].iov_len = entry.hdr_size;
57         iovec[1].iov_base = const_cast<char*>(msg);
58         iovec[1].iov_len = entry.len;
59 
60         return client_->sendDatav(iovec, 1 + (entry.len != 0)) == 0;
61     }
62 
Release()63     void Release() override {
64         reader_->release(client_);
65         client_->decRef();
66     }
67 
Shutdown()68     void Shutdown() override { shutdown(client_->getSocket(), SHUT_RDWR); }
69 
name() const70     std::string name() const override { return SocketClientToName(client_); }
71 
72   private:
73     LogReader* reader_;
74     SocketClient* client_;
75 };
76 
LogReader(LogBuffer * logbuf,LogReaderList * reader_list)77 LogReader::LogReader(LogBuffer* logbuf, LogReaderList* reader_list)
78     : SocketListener(getLogSocket(), true), log_buffer_(logbuf), reader_list_(reader_list) {}
79 
80 // Note returning false will release the SocketClient instance.
onDataAvailable(SocketClient * cli)81 bool LogReader::onDataAvailable(SocketClient* cli) {
82     static bool name_set;
83     if (!name_set) {
84         prctl(PR_SET_NAME, "logd.reader");
85         name_set = true;
86     }
87 
88     char buffer[255];
89 
90     int len = read(cli->getSocket(), buffer, sizeof(buffer) - 1);
91     if (len <= 0) {
92         DoSocketDelete(cli);
93         return false;
94     }
95     buffer[len] = '\0';
96 
97     // Clients are only allowed to send one command, disconnect them if they send another.
98     if (DoSocketDelete(cli)) {
99         return false;
100     }
101 
102     unsigned long tail = 0;
103     static const char _tail[] = " tail=";
104     char* cp = strstr(buffer, _tail);
105     if (cp) {
106         tail = atol(cp + sizeof(_tail) - 1);
107     }
108 
109     log_time start(log_time::EPOCH);
110     static const char _start[] = " start=";
111     cp = strstr(buffer, _start);
112     if (cp) {
113         // Parse errors will result in current time
114         start.strptime(cp + sizeof(_start) - 1, "%s.%q");
115     }
116 
117     std::chrono::steady_clock::time_point deadline = {};
118     static const char _timeout[] = " timeout=";
119     cp = strstr(buffer, _timeout);
120     if (cp) {
121         long timeout_seconds = atol(cp + sizeof(_timeout) - 1);
122         deadline = std::chrono::steady_clock::now() + std::chrono::seconds(timeout_seconds);
123     }
124 
125     unsigned int logMask = -1;
126     static const char _logIds[] = " lids=";
127     cp = strstr(buffer, _logIds);
128     if (cp) {
129         logMask = 0;
130         cp += sizeof(_logIds) - 1;
131         while (*cp != '\0') {
132             int val = 0;
133             while (isdigit(*cp)) {
134                 val = val * 10 + *cp - '0';
135                 ++cp;
136             }
137             logMask |= 1 << val;
138             if (*cp != ',') {
139                 break;
140             }
141             ++cp;
142         }
143     }
144 
145     pid_t pid = 0;
146     static const char _pid[] = " pid=";
147     cp = strstr(buffer, _pid);
148     if (cp) {
149         pid = atol(cp + sizeof(_pid) - 1);
150     }
151 
152     bool nonBlock = false;
153     if (!fastcmp<strncmp>(buffer, "dumpAndClose", 12)) {
154         // Allow writer to get some cycles, and wait for pending notifications
155         sched_yield();
156         logd_lock.lock();
157         logd_lock.unlock();
158         sched_yield();
159         nonBlock = true;
160     }
161 
162     bool privileged = clientHasLogCredentials(cli);
163     bool can_read_security = CanReadSecurityLogs(cli);
164     if (!can_read_security) {
165         logMask &= ~(1 << LOG_ID_SECURITY);
166     }
167 
168     std::unique_ptr<LogWriter> socket_log_writer(new SocketLogWriter(this, cli, privileged));
169 
170     uint64_t sequence = 1;
171     // Convert realtime to sequence number
172     if (start != log_time::EPOCH) {
173         bool start_time_set = false;
174         uint64_t last = sequence;
175         auto log_find_start = [pid, start, &sequence, &start_time_set, &last](
176                                       log_id_t, pid_t element_pid, uint64_t element_sequence,
177                                       log_time element_realtime) -> FilterResult {
178             if (pid && pid != element_pid) {
179                 return FilterResult::kSkip;
180             }
181             if (start == element_realtime) {
182                 sequence = element_sequence;
183                 start_time_set = true;
184                 return FilterResult::kStop;
185             } else {
186                 if (start < element_realtime) {
187                     sequence = last;
188                     start_time_set = true;
189                     return FilterResult::kStop;
190                 }
191                 last = element_sequence;
192             }
193             return FilterResult::kSkip;
194         };
195         auto lock = std::lock_guard{logd_lock};
196         auto flush_to_state = log_buffer_->CreateFlushToState(sequence, logMask);
197         log_buffer_->FlushTo(socket_log_writer.get(), *flush_to_state, log_find_start);
198 
199         if (!start_time_set) {
200             if (nonBlock) {
201                 return false;
202             }
203             sequence = log_buffer_->sequence();
204         }
205     }
206 
207     LOG(INFO) << android::base::StringPrintf(
208             "logdr: UID=%d GID=%d PID=%d %c tail=%lu logMask=%x pid=%d "
209             "start=%" PRIu64 "ns deadline=%" PRIi64 "ns",
210             cli->getUid(), cli->getGid(), cli->getPid(), nonBlock ? 'n' : 'b', tail, logMask,
211             (int)pid, start.nsec(), static_cast<int64_t>(deadline.time_since_epoch().count()));
212 
213     if (start == log_time::EPOCH) {
214         deadline = {};
215     }
216 
217     auto lock = std::lock_guard{logd_lock};
218     auto entry = std::make_unique<LogReaderThread>(log_buffer_, reader_list_,
219                                                    std::move(socket_log_writer), nonBlock, tail,
220                                                    logMask, pid, start, sequence, deadline);
221     // release client and entry reference counts once done
222     cli->incRef();
223     reader_list_->reader_threads().emplace_front(std::move(entry));
224 
225     // Set acceptable upper limit to wait for slow reader processing b/27242723
226     struct timeval t = { LOGD_SNDTIMEO, 0 };
227     setsockopt(cli->getSocket(), SOL_SOCKET, SO_SNDTIMEO, (const char*)&t,
228                sizeof(t));
229 
230     return true;
231 }
232 
DoSocketDelete(SocketClient * cli)233 bool LogReader::DoSocketDelete(SocketClient* cli) {
234     auto cli_name = SocketClientToName(cli);
235     auto lock = std::lock_guard{logd_lock};
236     for (const auto& reader : reader_list_->reader_threads()) {
237         if (reader->name() == cli_name) {
238             reader->Release();
239             return true;
240         }
241     }
242     return false;
243 }
244 
getLogSocket()245 int LogReader::getLogSocket() {
246     static const char socketName[] = "logdr";
247     int sock = android_get_control_socket(socketName);
248 
249     if (sock < 0) {
250         sock = socket_local_server(
251             socketName, ANDROID_SOCKET_NAMESPACE_RESERVED, SOCK_SEQPACKET);
252     }
253 
254     return sock;
255 }
256