8f639a4096
The executable can be inside a zip file using the same syntax used for
shared objects: path.zip!/libentry.so.
The linker currently requires an absolute path. This restriction could be
loosened, but it didn't seem important? If it allowed non-absolute paths,
we'd need to decide how to handle:
- foo/bar (relative to CWD?)
- foo (search PATH / LD_LIBRARY_PATH, or also relative to CWD?)
- foo.zip!/bar (normalize_path() requires an absolute path)
The linker adjusts the argc/argv passed to main() and to constructor
functions to hide the initial linker argument, but doesn't adjust the auxv
vector or files like /proc/self/{exe,cmdline,auxv,stat}. Those files will
report that the kernel loaded the linker as an executable.
I think the linker_logger.cpp change guarding against (g_argv == NULL)
isn't actually necessary, but it seemed like a good idea given that I'm
delaying initialization of g_argv until after C++ constructors have run.
Bug: http://b/112050209
Test: bionic unit tests
Change-Id: I846faf98b16fd34218946f6167e8b451897debe5
130 lines
4.4 KiB
C++
130 lines
4.4 KiB
C++
/*
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* Copyright (C) 2016 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "linker_logger.h"
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#include <string.h>
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#include <sys/prctl.h>
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#include <unistd.h>
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#include <string>
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#include <vector>
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#include <async_safe/log.h>
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#include "android-base/strings.h"
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#include "private/CachedProperty.h"
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LinkerLogger g_linker_logger;
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bool g_greylist_disabled = false;
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static uint32_t ParseProperty(const std::string& value) {
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if (value.empty()) {
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return 0;
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}
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std::vector<std::string> options = android::base::Split(value, ",");
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uint32_t flags = 0;
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for (const auto& o : options) {
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if (o == "dlerror") {
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flags |= kLogErrors;
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} else if (o == "dlopen") {
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flags |= kLogDlopen;
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} else if (o == "dlsym") {
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flags |= kLogDlsym;
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} else {
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async_safe_format_log(ANDROID_LOG_WARN, "linker", "Ignoring unknown debug.ld option \"%s\"",
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o.c_str());
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}
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}
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return flags;
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}
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static void GetAppSpecificProperty(char* buffer) {
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// Get process basename.
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const char* process_name_start = basename(g_argv[0]);
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// Remove ':' and everything after it. This is the naming convention for
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// services: https://developer.android.com/guide/components/services.html
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const char* process_name_end = strchr(process_name_start, ':');
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std::string process_name = (process_name_end != nullptr) ?
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std::string(process_name_start, (process_name_end - process_name_start)) :
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std::string(process_name_start);
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std::string property_name = std::string("debug.ld.app.") + process_name;
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__system_property_get(property_name.c_str(), buffer);
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}
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void LinkerLogger::ResetState() {
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// The most likely scenario app is not debuggable and
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// is running on a user build, in which case logging is disabled.
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if (prctl(PR_GET_DUMPABLE, 0, 0, 0, 0) == 0) {
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return;
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}
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// This is a convenient place to check whether the greylist should be disabled for testing.
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static CachedProperty greylist_disabled("debug.ld.greylist_disabled");
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bool old_value = g_greylist_disabled;
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g_greylist_disabled = (strcmp(greylist_disabled.Get(), "true") == 0);
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if (g_greylist_disabled != old_value) {
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async_safe_format_log(ANDROID_LOG_INFO, "linker", "%s greylist",
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g_greylist_disabled ? "Disabling" : "Enabling");
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}
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flags_ = 0;
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// For logging, check the flag applied to all processes first.
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static CachedProperty debug_ld_all("debug.ld.all");
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flags_ |= ParseProperty(debug_ld_all.Get());
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// Safeguard against a NULL g_argv. Ignore processes started without argv (http://b/33276926).
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if (g_argv == nullptr || g_argv[0] == nullptr) {
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return;
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}
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// Otherwise check the app-specific property too.
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// We can't easily cache the property here because argv[0] changes.
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char debug_ld_app[PROP_VALUE_MAX] = {};
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GetAppSpecificProperty(debug_ld_app);
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flags_ |= ParseProperty(debug_ld_app);
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}
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void LinkerLogger::Log(uint32_t type, const char* format, ...) {
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if ((flags_ & type) == 0) {
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return;
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}
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va_list ap;
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va_start(ap, format);
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async_safe_format_log_va_list(ANDROID_LOG_DEBUG, "linker", format, ap);
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va_end(ap);
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}
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