1 /*
2 * Copyright (C) 2016 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include "linker_logger.h"
30
31 #include <string.h>
32 #include <sys/prctl.h>
33 #include <unistd.h>
34
35 #include <string>
36 #include <vector>
37
38 #include <async_safe/log.h>
39
40 #include "android-base/strings.h"
41 #include "private/CachedProperty.h"
42
43 LinkerLogger g_linker_logger;
44 bool g_greylist_disabled = false;
45
ParseProperty(const std::string & value)46 static uint32_t ParseProperty(const std::string& value) {
47 if (value.empty()) {
48 return 0;
49 }
50
51 std::vector<std::string> options = android::base::Split(value, ",");
52
53 uint32_t flags = 0;
54
55 for (const auto& o : options) {
56 if (o == "dlerror") {
57 flags |= kLogErrors;
58 } else if (o == "dlopen") {
59 flags |= kLogDlopen;
60 } else if (o == "dlsym") {
61 flags |= kLogDlsym;
62 } else {
63 async_safe_format_log(ANDROID_LOG_WARN, "linker", "Ignoring unknown debug.ld option \"%s\"",
64 o.c_str());
65 }
66 }
67
68 return flags;
69 }
70
GetAppSpecificProperty(char * buffer)71 static void GetAppSpecificProperty(char* buffer) {
72 // Get process basename.
73 const char* process_name_start = basename(g_argv[0]);
74
75 // Remove ':' and everything after it. This is the naming convention for
76 // services: https://developer.android.com/guide/components/services.html
77 const char* process_name_end = strchr(process_name_start, ':');
78
79 std::string process_name = (process_name_end != nullptr) ?
80 std::string(process_name_start, (process_name_end - process_name_start)) :
81 std::string(process_name_start);
82
83 std::string property_name = std::string("debug.ld.app.") + process_name;
84 __system_property_get(property_name.c_str(), buffer);
85 }
86
ResetState()87 void LinkerLogger::ResetState() {
88 // The most likely scenario app is not debuggable and
89 // is running on a user build, in which case logging is disabled.
90 if (prctl(PR_GET_DUMPABLE, 0, 0, 0, 0) == 0) {
91 return;
92 }
93
94 // This is a convenient place to check whether the greylist should be disabled for testing.
95 static CachedProperty greylist_disabled("debug.ld.greylist_disabled");
96 bool old_value = g_greylist_disabled;
97 g_greylist_disabled = (strcmp(greylist_disabled.Get(), "true") == 0);
98 if (g_greylist_disabled != old_value) {
99 async_safe_format_log(ANDROID_LOG_INFO, "linker", "%s greylist",
100 g_greylist_disabled ? "Disabling" : "Enabling");
101 }
102
103 flags_ = 0;
104
105 // For logging, check the flag applied to all processes first.
106 static CachedProperty debug_ld_all("debug.ld.all");
107 flags_ |= ParseProperty(debug_ld_all.Get());
108
109 // Safeguard against a NULL g_argv. Ignore processes started without argv (http://b/33276926).
110 if (g_argv == nullptr || g_argv[0] == nullptr) {
111 return;
112 }
113
114 // Otherwise check the app-specific property too.
115 // We can't easily cache the property here because argv[0] changes.
116 char debug_ld_app[PROP_VALUE_MAX] = {};
117 GetAppSpecificProperty(debug_ld_app);
118 flags_ |= ParseProperty(debug_ld_app);
119 }
120
Log(const char * format,...)121 void LinkerLogger::Log(const char* format, ...) {
122 va_list ap;
123 va_start(ap, format);
124 async_safe_format_log_va_list(ANDROID_LOG_DEBUG, "linker", format, ap);
125 va_end(ap);
126 }
127