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 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 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 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 } 120 121 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