1 /*
2 * Copyright (C) 2017 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 "berberis/base/tracing.h"
18
19 #include <fcntl.h>
20 #include <netdb.h>
21 #include <sys/socket.h>
22 #include <sys/stat.h>
23 #include <sys/types.h>
24
25 #include <string>
26
27 #include "berberis/base/checks.h"
28 #include "berberis/base/config_globals.h"
29 #include "berberis/base/file.h"
30 #include "berberis/base/logging.h"
31 #include "berberis/base/scoped_errno.h"
32
33 namespace berberis {
34
35 namespace {
36
TraceToFile(std::string trace_filename)37 int TraceToFile(std::string trace_filename) {
38 if (trace_filename == "1") {
39 ALOGD("tracing to stdout");
40 return STDOUT_FILENO;
41 }
42
43 if (trace_filename == "2") {
44 ALOGD("tracing to stderr");
45 return STDERR_FILENO;
46 }
47
48 // If the provided path is relative set it up under app's private directory.
49 if (trace_filename.at(0) != '/') {
50 const char* app_private_dir = GetAppPrivateDir();
51 if (!app_private_dir) {
52 ALOGE("not tracing - app's private directory is undefined");
53 return -1;
54 }
55 trace_filename = std::string(app_private_dir) + "/" + trace_filename;
56 }
57
58 if (uid_t uid = getuid()) {
59 // If not running as root, should be output file directory owner.
60 // To trace an app, use output file in app's data directory.
61 std::string dir = Dirname(trace_filename);
62 struct stat dir_stat;
63 if (stat(dir.c_str(), &dir_stat)) {
64 ALOGE("not tracing - failed to stat \"%s\"", dir.c_str());
65 return -1;
66 }
67 if (uid != dir_stat.st_uid) {
68 ALOGE("not tracing - uid mismatch of \"%s\"", dir.c_str());
69 return -1;
70 }
71 }
72
73 int fd = open(trace_filename.c_str(), O_WRONLY | O_CREAT | O_APPEND | O_CLOEXEC, S_IWUSR);
74 if (fd == -1) {
75 ALOGE("not tracing - failed to open output file \"%s\"", trace_filename.c_str());
76 return -1;
77 }
78
79 ALOGD("tracing to \"%s\"", trace_filename.c_str());
80 return fd;
81 }
82
83 // At the moment, only accept ":<port>", assume localhost:<port>
TraceToSocket(const char * env)84 int TraceToSocket(const char* env) {
85 CHECK_EQ(':', env[0]);
86
87 struct addrinfo hints {};
88 hints.ai_family = AF_UNSPEC;
89 hints.ai_socktype = SOCK_STREAM;
90
91 struct addrinfo* results;
92 if (getaddrinfo("localhost", env + 1, &hints, &results) != 0) {
93 ALOGE("not tracing - failed to get info for \"%s\"", env);
94 return -1;
95 }
96
97 for (auto info = results; info; info = info->ai_next) {
98 int fd = socket(info->ai_family, info->ai_socktype, info->ai_protocol);
99 if (fd != -1) {
100 if (connect(fd, info->ai_addr, info->ai_addrlen) != -1) {
101 freeaddrinfo(results);
102 ALOGD("tracing to \"localhost%s\"", env);
103 return fd;
104 }
105
106 close(fd);
107 }
108 }
109
110 freeaddrinfo(results);
111 ALOGE("not tracing - failed to connect to \"%s\"", env);
112 return -1;
113 }
114
115 } // namespace
116
117 int Tracing::fd_ = -1;
118
InitImpl()119 void Tracing::InitImpl() {
120 ScopedErrno scoped_errno;
121
122 auto env = GetTracingConfig();
123 if (!env || !env[0]) {
124 return;
125 }
126
127 if (const char* filter_end = strchr(env, '=')) {
128 const char* app = GetAppPackageName();
129 if (!app || strncmp(app, env, filter_end - env) != 0) {
130 ALOGD("not tracing - filtered out");
131 return;
132 }
133 env = filter_end + 1;
134 }
135
136 if (env[0] == ':') {
137 fd_ = TraceToSocket(env);
138 } else {
139 fd_ = TraceToFile(env);
140 }
141 }
142
143 } // namespace berberis
144