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
43LinkerLogger g_linker_logger;
44bool g_greylist_disabled = false;
45
46static 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
71static 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
87void 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  // Ignore processes started without argv (http://b/33276926).
110  if (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
121void LinkerLogger::Log(uint32_t type, const char* format, ...) {
122  if ((flags_ & type) == 0) {
123    return;
124  }
125
126  va_list ap;
127  va_start(ap, format);
128  async_safe_format_log_va_list(ANDROID_LOG_DEBUG, "linker", format, ap);
129  va_end(ap);
130}
131