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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.
*/
/*
* A tool loads keys to keyring.
*/
#include <dirent.h>
#include <errno.h>
#include <sys/types.h>
#include <unistd.h>
#include <fstream>
#include <iostream>
#include <iterator>
#include <sstream>
#include <string>
#include <vector>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android-base/strings.h>
#include <keyutils.h>
static constexpr int kMaxCertSize = 4096;
// Add all the certs from directory path to keyring with keyring_id. Returns the number of keys
// added.
int AddKeys(const std::string& path, const key_serial_t keyring_id, const std::string& keyring_desc,
int start_index) {
std::unique_ptr<DIR, int (*)(DIR*)> dir(opendir(path.c_str()), closedir);
if (!dir) {
PLOG(WARNING) << "Failed to open directory " << path;
return 0;
}
int keys_added = 0;
struct dirent* dp;
while ((dp = readdir(dir.get())) != NULL) {
if (dp->d_type != DT_REG) {
continue;
}
std::string cert_path = path + "/" + dp->d_name;
std::string cert_buf;
if (!android::base::ReadFileToString(cert_path, &cert_buf, false /* follow_symlinks */)) {
LOG(ERROR) << "Failed to read " << cert_path;
continue;
}
if (cert_buf.size() > kMaxCertSize) {
LOG(ERROR) << "Certficate size too large: " << cert_path;
continue;
}
// Add key to keyring.
int key_desc_index = keys_added + start_index;
std::string key_desc = keyring_desc + "-key" + std::to_string(key_desc_index);
key_serial_t key =
add_key("asymmetric", key_desc.c_str(), &cert_buf[0], cert_buf.size(), keyring_id);
if (key < 0) {
PLOG(ERROR) << "Failed to add key to keyring: " << cert_path;
continue;
}
keys_added++;
}
return keys_added;
}
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>{}};
}
// Find the keyring id. Because request_key(2) syscall is not available or the key is
// kernel keyring, the id is looked up from /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.
bool GetKeyringId(const std::string& keyring_desc, key_serial_t* keyring_id) {
if (!keyring_id) {
LOG(ERROR) << "keyring_id is null";
return false;
}
// 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 false;
}
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 = 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;
}
*keyring_id = std::stoi(key_id, nullptr, 16);
return true;
}
return false;
}
static void Usage(int exit_code) {
fprintf(stderr, "usage: mini-keyctl -c PATHS -s DESCRIPTION\n");
fprintf(stderr, "\n");
fprintf(stderr, "-c, --cert_dirs the certificate locations, separated by comma\n");
fprintf(stderr, "-k, --keyring the keyring description\n");
_exit(exit_code);
}
int main(int argc, char** argv) {
if (argc < 5) Usage(1);
std::string arg_cert_dirs;
std::string arg_keyring_desc;
for (int i = 1; i < argc; i++) {
std::string option = argv[i];
if (option == "-c" || option == "--cert_dirs") {
if (i + 1 < argc) arg_cert_dirs = argv[++i];
} else if (option == "-k" || option == "--keyring") {
if (i + 1 < argc) arg_keyring_desc = argv[++i];
}
}
if (arg_cert_dirs.empty() || arg_keyring_desc.empty()) {
LOG(ERROR) << "Missing cert_dirs or keyring desc";
Usage(1);
}
// Get the keyring id
key_serial_t key_ring_id;
if (!GetKeyringId(arg_keyring_desc, &key_ring_id)) {
PLOG(ERROR) << "Can't find keyring with " << arg_keyring_desc;
return 1;
}
std::vector<std::string> cert_dirs = android::base::Split(arg_cert_dirs, ",");
int start_index = 0;
for (const auto& cert_dir : cert_dirs) {
int keys_added = AddKeys(cert_dir, key_ring_id, arg_keyring_desc, start_index);
start_index += keys_added;
}
// Prevent new keys to be added.
if (!android::base::GetBoolProperty("ro.debuggable", false) &&
keyctl_restrict_keyring(key_ring_id, nullptr, nullptr) < 0) {
PLOG(ERROR) << "Failed to restrict key ring " << arg_keyring_desc;
return 1;
}
return 0;
}
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