114 lines
2.9 KiB
C++
114 lines
2.9 KiB
C++
/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "berberis/kernel_api/exec_emulation.h"
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#include <unistd.h>
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#include <cstring>
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#include "berberis/base/mmap.h"
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#include "berberis/base/strings.h"
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namespace berberis {
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namespace {
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bool IsPlatformVar(const char* s) {
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return StartsWith(s, "LD_CONFIG_FILE=") || StartsWith(s, "LD_LIBRARY_PATH=") ||
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StartsWith(s, "LD_DEBUG=") || StartsWith(s, "LD_PRELOAD=");
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}
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char* const* MangleGuestEnvp(ScopedMmap* dst, char* const* envp) {
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if (envp == nullptr) {
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return nullptr;
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}
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int env_count = 0;
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int text_size = 0;
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int mangle_count = 0;
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for (;; ++env_count) {
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char* env = envp[env_count];
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if (env == nullptr) {
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break;
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}
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if (IsPlatformVar(env)) {
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++mangle_count;
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}
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text_size += strlen(env) + 1; // count terminating '\0'
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}
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if (mangle_count == 0) {
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return envp;
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}
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auto [guest_prefix, guest_prefix_size] = GetGuestPlatformVarPrefixWithSize();
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size_t array_size = sizeof(char*) * (env_count + 1); // text pointers + terminating nullptr
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dst->Init(array_size + text_size + // array + orig text
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guest_prefix_size * mangle_count); // added prefixes
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char** new_array = static_cast<char**>(dst->data());
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char* new_text = static_cast<char*>(dst->data()) + array_size;
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for (int i = 0; i < env_count; ++i) {
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char* env = envp[i];
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new_array[i] = new_text;
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if (IsPlatformVar(env)) {
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strcpy(new_text, guest_prefix);
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new_text += guest_prefix_size;
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}
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strcpy(new_text, env);
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new_text += strlen(env) + 1; // count terminating '\0'
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}
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new_array[env_count] = nullptr; // add terminating nullptr
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return new_array;
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}
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} // namespace
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char** DemangleGuestEnvp(char** dst, char** envp) {
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auto [guest_prefix, guest_prefix_size] = GetGuestPlatformVarPrefixWithSize();
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for (; *envp; ++envp) {
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char* env = *envp;
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if (IsPlatformVar(env)) {
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continue;
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}
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if (StartsWith(env, guest_prefix) && IsPlatformVar(env + guest_prefix_size)) {
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env += guest_prefix_size;
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}
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*dst++ = env;
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}
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*dst++ = nullptr;
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return dst;
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}
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int ExecveForGuest(const char* filename, char* const argv[], char* const envp[]) {
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ScopedMmap new_envp;
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return execve(filename, argv, MangleGuestEnvp(&new_envp, envp));
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}
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} // namespace berberis
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