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/*
* Copyright (C) 2019 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <mini_keyctl_utils.h>
#include <fstream>
#include <iterator>
#include <sstream>
#include <string>
#include <vector>
#include <android-base/logging.h>
#include <android-base/parseint.h>
namespace android {
namespace {
std::vector<std::string> SplitBySpace(const std::string& s) {
std::istringstream iss(s);
return std::vector<std::string>{std::istream_iterator<std::string>{iss},
std::istream_iterator<std::string>{}};
}
} // namespace
// Find the keyring id. request_key(2) only finds keys in the process, session or thread keyring
// hierarchy, but not internal keyring of a kernel subsystem (e.g. .fs-verity). To support all
// cases, this function looks up a keyring's ID by parsing /proc/keys. The keyring description may
// contain other information in the descritption section depending on the key type, only the first
// word in the keyring description is used for searching.
key_serial_t GetKeyringId(const std::string& keyring_desc) {
// If the keyring id is already a hex number, directly convert it to keyring id
key_serial_t keyring_id;
if (android::base::ParseInt(keyring_desc.c_str(), &keyring_id)) {
return keyring_id;
}
// Only keys allowed by SELinux rules will be shown here.
std::ifstream proc_keys_file("/proc/keys");
if (!proc_keys_file.is_open()) {
PLOG(ERROR) << "Failed to open /proc/keys";
return -1;
}
std::string line;
while (getline(proc_keys_file, line)) {
std::vector<std::string> tokens = SplitBySpace(line);
if (tokens.size() < 9) {
continue;
}
std::string key_id = "0x" + tokens[0];
std::string key_type = tokens[7];
// The key description may contain space.
std::string key_desc_prefix = tokens[8];
// The prefix has a ":" at the end
std::string key_desc_pattern = keyring_desc + ":";
if (key_type != "keyring" || key_desc_prefix != key_desc_pattern) {
continue;
}
if (!android::base::ParseInt(key_id.c_str(), &keyring_id)) {
LOG(ERROR) << "Unexpected key format in /proc/keys: " << key_id;
return -1;
}
return keyring_id;
}
return -1;
}
} // namespace android
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