84 lines
2.7 KiB
C++
84 lines
2.7 KiB
C++
/*
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* Copyright (C) 2019 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 <mini_keyctl_utils.h>
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#include <fstream>
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#include <iterator>
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#include <sstream>
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#include <string>
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#include <vector>
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#include <android-base/logging.h>
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#include <android-base/parseint.h>
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namespace android {
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namespace {
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std::vector<std::string> SplitBySpace(const std::string& s) {
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std::istringstream iss(s);
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return std::vector<std::string>{std::istream_iterator<std::string>{iss},
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std::istream_iterator<std::string>{}};
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}
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} // namespace
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// Find the keyring id. request_key(2) only finds keys in the process, session or thread keyring
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// hierarchy, but not internal keyring of a kernel subsystem (e.g. .fs-verity). To support all
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// cases, this function looks up a keyring's ID by parsing /proc/keys. The keyring description may
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// contain other information in the descritption section depending on the key type, only the first
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// word in the keyring description is used for searching.
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key_serial_t GetKeyringId(const std::string& keyring_desc) {
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// If the keyring id is already a hex number, directly convert it to keyring id
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key_serial_t keyring_id;
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if (android::base::ParseInt(keyring_desc.c_str(), &keyring_id)) {
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return keyring_id;
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}
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// Only keys allowed by SELinux rules will be shown here.
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std::ifstream proc_keys_file("/proc/keys");
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if (!proc_keys_file.is_open()) {
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PLOG(ERROR) << "Failed to open /proc/keys";
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return -1;
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}
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std::string line;
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while (getline(proc_keys_file, line)) {
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std::vector<std::string> tokens = SplitBySpace(line);
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if (tokens.size() < 9) {
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continue;
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}
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std::string key_id = "0x" + tokens[0];
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std::string key_type = tokens[7];
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// The key description may contain space.
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std::string key_desc_prefix = tokens[8];
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// The prefix has a ":" at the end
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std::string key_desc_pattern = keyring_desc + ":";
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if (key_type != "keyring" || key_desc_prefix != key_desc_pattern) {
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continue;
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}
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if (!android::base::ParseInt(key_id.c_str(), &keyring_id)) {
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LOG(ERROR) << "Unexpected key format in /proc/keys: " << key_id;
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return -1;
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}
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return keyring_id;
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}
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return -1;
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}
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} // namespace android
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