Add a tool to add keys to keyring. (4a5c352e) · Commits · e / os / android_system_core

libkeyutils/Android.bp

+13 −0

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		@@ -16,3 +16,16 @@ cc_test {
		srcs: ["keyutils_test.cpp"],
		test_suites: ["device-tests"],
		}

		cc_binary {
		name: "mini-keyctl",
		srcs: ["mini_keyctl.cpp"],

		shared_libs: [
		"libbase",
		"libkeyutils",
		"liblog",
		],

		cflags: ["-Werror", "-Wall", "-Wextra"],
		}

libkeyutils/include/keyutils.h

+4 −0

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		@@ -51,6 +51,10 @@ long keyctl_setperm(key_serial_t id, int permissions);

		long keyctl_unlink(key_serial_t key, key_serial_t keyring);

		long keyctl_restrict_keyring(key_serial_t keyring, const char* type, const char* restriction);

		long keyctl_get_security(key_serial_t key, char* buffer, size_t buflen);

		__END_DECLS

		#endif

libkeyutils/keyutils.cpp

+8 −0

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		@@ -69,3 +69,11 @@ long keyctl_setperm(key_serial_t id, int permissions) {
		long keyctl_unlink(key_serial_t key, key_serial_t keyring) {
		return keyctl(KEYCTL_UNLINK, key, keyring);
		}

		long keyctl_restrict_keyring(key_serial_t keyring, const char* type, const char* restriction) {
		return keyctl(KEYCTL_RESTRICT_KEYRING, keyring, type, restriction);
		}

		long keyctl_get_security(key_serial_t id, char* buffer, size_t buflen) {
		return keyctl(KEYCTL_GET_SECURITY, id, buffer, buflen);
		}

libkeyutils/mini_keyctl.cpp

0 → 100644

+176 −0

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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;
		}