Move adbd authentication into its own library. (b789fb14) · Commits · e / os / platform_frameworks_native

Android.bp

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		@@ -7,6 +7,7 @@ ndk_headers {
		}

		subdirs = [
		"adbd_auth",
		"cmds/*",
		"headers",
		"libs/*",

libs/adbd_auth/Android.bp

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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.

		cc_library {
		name: "libadbd_auth",
		cflags: [
		"-Wall",
		"-Wextra",
		"-Wthread-safety",
		"-Werror",
		],
		srcs: ["adbd_auth.cpp"],
		export_include_dirs: ["include"],

		version_script: "libadbd_auth.map.txt",
		stubs: {
		symbol_file: "libadbd_auth.map.txt",
		},

		host_supported: true,
		recovery_available: true,

		shared_libs: [
		"libbase",
		"libcutils",
		"liblog",
		],
		}

libs/adbd_auth/adbd_auth.cpp

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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.
		*/

		#define ANDROID_BASE_UNIQUE_FD_DISABLE_IMPLICIT_CONVERSION

		#include "include/adbd_auth.h"

		#include <inttypes.h>
		#include <sys/epoll.h>
		#include <sys/eventfd.h>
		#include <sys/uio.h>

		#include <chrono>
		#include <deque>
		#include <string>
		#include <string_view>
		#include <tuple>
		#include <unordered_map>
		#include <utility>
		#include <variant>
		#include <vector>

		#include <android-base/file.h>
		#include <android-base/logging.h>
		#include <android-base/macros.h>
		#include <android-base/strings.h>
		#include <android-base/thread_annotations.h>
		#include <android-base/unique_fd.h>
		#include <cutils/sockets.h>

		using android::base::unique_fd;

		struct AdbdAuthPacketAuthenticated {
		std::string public_key;
		};

		struct AdbdAuthPacketDisconnected {
		std::string public_key;
		};

		struct AdbdAuthPacketRequestAuthorization {
		std::string public_key;
		};

		using AdbdAuthPacket = std::variant<AdbdAuthPacketAuthenticated, AdbdAuthPacketDisconnected,
		AdbdAuthPacketRequestAuthorization>;

		struct AdbdAuthContext {
		static constexpr uint64_t kEpollConstSocket = 0;
		static constexpr uint64_t kEpollConstEventFd = 1;
		static constexpr uint64_t kEpollConstFramework = 2;

		public:
		explicit AdbdAuthContext(AdbdAuthCallbacksV1* callbacks) : next_id_(0), callbacks_(*callbacks) {
		epoll_fd_.reset(epoll_create1(EPOLL_CLOEXEC));
		if (epoll_fd_ == -1) {
		PLOG(FATAL) << "failed to create epoll fd";
		}

		event_fd_.reset(eventfd(0, EFD_CLOEXEC \| EFD_NONBLOCK));
		if (event_fd_ == -1) {
		PLOG(FATAL) << "failed to create eventfd";
		}

		sock_fd_.reset(android_get_control_socket("adbd"));
		if (sock_fd_ == -1) {
		PLOG(ERROR) << "failed to get adbd authentication socket";
		} else {
		if (fcntl(sock_fd_.get(), F_SETFD, FD_CLOEXEC) != 0) {
		PLOG(FATAL) << "failed to make adbd authentication socket cloexec";
		}

		if (fcntl(sock_fd_.get(), F_SETFL, O_NONBLOCK) != 0) {
		PLOG(FATAL) << "failed to make adbd authentication socket nonblocking";
		}

		if (listen(sock_fd_.get(), 4) != 0) {
		PLOG(FATAL) << "failed to listen on adbd authentication socket";
		}
		}
		}

		AdbdAuthContext(const AdbdAuthContext& copy) = delete;
		AdbdAuthContext(AdbdAuthContext&& move) = delete;
		AdbdAuthContext& operator=(const AdbdAuthContext& copy) = delete;
		AdbdAuthContext& operator=(AdbdAuthContext&& move) = delete;

		uint64_t NextId() { return next_id_++; }

		void DispatchPendingPrompt() REQUIRES(mutex_) {
		if (dispatched_prompt_) {
		LOG(INFO) << "adbd_auth: prompt currently pending, skipping";
		return;
		}

		if (pending_prompts_.empty()) {
		LOG(INFO) << "adbd_auth: no prompts to send";
		return;
		}

		LOG(INFO) << "adbd_auth: prompting user for adb authentication";
		auto [id, public_key, arg] = std::move(pending_prompts_.front());
		pending_prompts_.pop_front();

		this->output_queue_.emplace_back(
		AdbdAuthPacketRequestAuthorization{.public_key = public_key});

		Interrupt();
		dispatched_prompt_ = std::make_tuple(id, public_key, arg);
		}

		void UpdateFrameworkWritable() REQUIRES(mutex_) {
		// This might result in redundant calls to EPOLL_CTL_MOD if, for example, we get notified
		// at the same time as a framework connection, but that's unlikely and this doesn't need to
		// be fast anyway.
		if (framework_fd_ != -1) {
		struct epoll_event event;
		event.events = EPOLLIN;
		if (!output_queue_.empty()) {
		LOG(INFO) << "marking framework writable";
		event.events \|= EPOLLOUT;
		}
		event.data.u64 = kEpollConstFramework;
		CHECK_EQ(0, epoll_ctl(epoll_fd_.get(), EPOLL_CTL_MOD, framework_fd_.get(), &event));
		}
		}

		void ReplaceFrameworkFd(unique_fd new_fd) REQUIRES(mutex_) {
		LOG(INFO) << "received new framework fd " << new_fd.get()
		<< " (current = " << framework_fd_.get() << ")";

		// If we already had a framework fd, clean up after ourselves.
		if (framework_fd_ != -1) {
		output_queue_.clear();
		dispatched_prompt_.reset();
		CHECK_EQ(0, epoll_ctl(epoll_fd_.get(), EPOLL_CTL_DEL, framework_fd_.get(), nullptr));
		framework_fd_.reset();
		}

		if (new_fd != -1) {
		struct epoll_event event;
		event.events = EPOLLIN;
		if (!output_queue_.empty()) {
		LOG(INFO) << "marking framework writable";
		event.events \|= EPOLLOUT;
		}
		event.data.u64 = kEpollConstFramework;
		CHECK_EQ(0, epoll_ctl(epoll_fd_.get(), EPOLL_CTL_ADD, new_fd.get(), &event));
		framework_fd_ = std::move(new_fd);
		}
		}

		void HandlePacket(std::string_view packet) REQUIRES(mutex_) {
		LOG(INFO) << "received packet: " << packet;

		if (packet.length() < 2) {
		LOG(ERROR) << "received packet of invalid length";
		ReplaceFrameworkFd(unique_fd());
		}

		if (packet[0] == 'O' && packet[1] == 'K') {
		CHECK(this->dispatched_prompt_.has_value());
		auto& [id, key, arg] = *this->dispatched_prompt_;
		keys_.emplace(id, std::move(key));

		this->callbacks_.key_authorized(arg, id);
		this->dispatched_prompt_ = std::nullopt;
		} else if (packet[0] == 'N' && packet[1] == 'O') {
		CHECK_EQ(2UL, packet.length());
		// TODO: Do we want a callback if the key is denied?
		this->dispatched_prompt_ = std::nullopt;
		DispatchPendingPrompt();
		} else {
		LOG(ERROR) << "unhandled packet: " << packet;
		ReplaceFrameworkFd(unique_fd());
		}
		}

		bool SendPacket() REQUIRES(mutex_) {
		if (output_queue_.empty()) {
		return false;
		}

		CHECK_NE(-1, framework_fd_.get());

		auto& packet = output_queue_.front();
		struct iovec iovs[2];
		if (auto* p = std::get_if<AdbdAuthPacketAuthenticated>(&packet)) {
		iovs[0].iov_base = const_cast<char*>("CK");
		iovs[0].iov_len = 2;
		iovs[1].iov_base = p->public_key.data();
		iovs[1].iov_len = p->public_key.size();
		} else if (auto* p = std::get_if<AdbdAuthPacketDisconnected>(&packet)) {
		iovs[0].iov_base = const_cast<char*>("DC");
		iovs[0].iov_len = 2;
		iovs[1].iov_base = p->public_key.data();
		iovs[1].iov_len = p->public_key.size();
		} else if (auto* p = std::get_if<AdbdAuthPacketRequestAuthorization>(&packet)) {
		iovs[0].iov_base = const_cast<char*>("PK");
		iovs[0].iov_len = 2;
		iovs[1].iov_base = p->public_key.data();
		iovs[1].iov_len = p->public_key.size();
		} else {
		LOG(FATAL) << "unhandled packet type?";
		}

		output_queue_.pop_front();

		ssize_t rc = writev(framework_fd_.get(), iovs, 2);
		if (rc == -1 && errno != EAGAIN && errno != EWOULDBLOCK) {
		PLOG(ERROR) << "failed to write to framework fd";
		ReplaceFrameworkFd(unique_fd());
		return false;
		}

		return true;
		}

		void Run() {
		if (sock_fd_ == -1) {
		LOG(ERROR) << "adbd authentication socket unavailable, disabling user prompts";
		} else {
		struct epoll_event event;
		event.events = EPOLLIN;
		event.data.u64 = kEpollConstSocket;
		CHECK_EQ(0, epoll_ctl(epoll_fd_.get(), EPOLL_CTL_ADD, sock_fd_.get(), &event));
		}

		{
		struct epoll_event event;
		event.events = EPOLLIN;
		event.data.u64 = kEpollConstEventFd;
		CHECK_EQ(0, epoll_ctl(epoll_fd_.get(), EPOLL_CTL_ADD, event_fd_.get(), &event));
		}

		while (true) {
		struct epoll_event events[3];
		int rc = TEMP_FAILURE_RETRY(epoll_wait(epoll_fd_.get(), events, 3, -1));
		if (rc == -1) {
		PLOG(FATAL) << "epoll_wait failed";
		} else if (rc == 0) {
		LOG(FATAL) << "epoll_wait returned 0";
		}

		bool restart = false;
		for (int i = 0; i < rc; ++i) {
		if (restart) {
		break;
		}

		struct epoll_event& event = events[i];
		switch (event.data.u64) {
		case kEpollConstSocket: {
		unique_fd new_framework_fd(accept4(sock_fd_.get(), nullptr, nullptr,
		SOCK_CLOEXEC \| SOCK_NONBLOCK));
		if (new_framework_fd == -1) {
		PLOG(FATAL) << "failed to accept framework fd";
		}

		LOG(INFO) << "adbd_auth: received a new framework connection";
		std::lock_guard<std::mutex> lock(mutex_);
		ReplaceFrameworkFd(std::move(new_framework_fd));

		// Stop iterating over events: one of the later ones might be the old
		// framework fd.
		restart = false;
		break;
		}

		case kEpollConstEventFd: {
		// We were woken up to write something.
		uint64_t dummy;
		int rc = TEMP_FAILURE_RETRY(read(event_fd_.get(), &dummy, sizeof(dummy)));
		if (rc != 8) {
		PLOG(FATAL) << "failed to read from eventfd (rc = " << rc << ")";
		}

		std::lock_guard<std::mutex> lock(mutex_);
		UpdateFrameworkWritable();
		break;
		}

		case kEpollConstFramework: {
		char buf[4096];
		if (event.events & EPOLLIN) {
		int rc = TEMP_FAILURE_RETRY(read(framework_fd_.get(), buf, sizeof(buf)));
		if (rc == -1) {
		LOG(FATAL) << "failed to read from framework fd";
		} else if (rc == 0) {
		LOG(INFO) << "hit EOF on framework fd";
		std::lock_guard<std::mutex> lock(mutex_);
		ReplaceFrameworkFd(unique_fd());
		} else {
		std::lock_guard<std::mutex> lock(mutex_);
		HandlePacket(std::string_view(buf, rc));
		}
		}

		if (event.events & EPOLLOUT) {
		std::lock_guard<std::mutex> lock(mutex_);
		while (SendPacket()) {
		continue;
		}
		UpdateFrameworkWritable();
		}

		break;
		}
		}
		}
		}
		}

		static constexpr const char* key_paths[] = {"/adb_keys", "/data/misc/adb/adb_keys"};
		void IteratePublicKeys(bool (callback)(const char, size_t, void), void arg) {
		for (const auto& path : key_paths) {
		if (access(path, R_OK) == 0) {
		LOG(INFO) << "Loading keys from " << path;
		std::string content;
		if (!android::base::ReadFileToString(path, &content)) {
		PLOG(ERROR) << "Couldn't read " << path;
		continue;
		}
		for (const auto& line : android::base::Split(content, "\n")) {
		if (!callback(line.data(), line.size(), arg)) {
		return;
		}
		}
		}
		}
		}

		uint64_t PromptUser(std::string_view public_key, void* arg) EXCLUDES(mutex_) {
		uint64_t id = NextId();

		std::lock_guard<std::mutex> lock(mutex_);
		pending_prompts_.emplace_back(id, public_key, arg);
		DispatchPendingPrompt();
		return id;
		}

		uint64_t NotifyAuthenticated(std::string_view public_key) EXCLUDES(mutex_) {
		uint64_t id = NextId();
		std::lock_guard<std::mutex> lock(mutex_);
		keys_.emplace(id, public_key);
		output_queue_.emplace_back(
		AdbdAuthPacketDisconnected{.public_key = std::string(public_key)});
		return id;
		}

		void NotifyDisconnected(uint64_t id) EXCLUDES(mutex_) {
		std::lock_guard<std::mutex> lock(mutex_);
		auto it = keys_.find(id);
		if (it == keys_.end()) {
		LOG(DEBUG) << "couldn't find public key to notify disconnection, skipping";
		return;
		}
		output_queue_.emplace_back(AdbdAuthPacketDisconnected{.public_key = std::move(it->second)});
		keys_.erase(it);
		}

		// Interrupt the worker thread to do some work.
		void Interrupt() {
		uint64_t value = 1;
		ssize_t rc = write(event_fd_.get(), &value, sizeof(value));
		if (rc == -1) {
		PLOG(FATAL) << "write to eventfd failed";
		} else if (rc != sizeof(value)) {
		LOG(FATAL) << "write to eventfd returned short (" << rc << ")";
		}
		}

		unique_fd epoll_fd_;
		unique_fd event_fd_;
		unique_fd sock_fd_;
		unique_fd framework_fd_;

		std::atomic<uint64_t> next_id_;
		AdbdAuthCallbacksV1 callbacks_;

		std::mutex mutex_;
		std::unordered_map<uint64_t, std::string> keys_ GUARDED_BY(mutex_);

		// We keep two separate queues: one to handle backpressure from the socket (output_queue_)
		// and one to make sure we only dispatch one authrequest at a time (pending_prompts_).
		std::deque<AdbdAuthPacket> output_queue_;

		std::optional<std::tuple<uint64_t, std::string, void*>> dispatched_prompt_ GUARDED_BY(mutex_);
		std::deque<std::tuple<uint64_t, std::string, void*>> pending_prompts_ GUARDED_BY(mutex_);
		};

		AdbdAuthContext* adbd_auth_new(AdbdAuthCallbacks* callbacks) {
		if (callbacks->version != 1) {
		LOG(ERROR) << "received unknown AdbdAuthCallbacks version " << callbacks->version;
		return nullptr;
		}

		return new AdbdAuthContext(&callbacks->callbacks.v1);
		}

		void adbd_auth_delete(AdbdAuthContext* ctx) {
		delete ctx;
		}

		void adbd_auth_run(AdbdAuthContext* ctx) {
		return ctx->Run();
		}

		void adbd_auth_get_public_keys(AdbdAuthContext* ctx,
		bool (callback)(const char public_key, size_t len, void* arg),
		void* arg) {
		ctx->IteratePublicKeys(callback, arg);
		}

		uint64_t adbd_auth_notify_auth(AdbdAuthContext* ctx, const char* public_key, size_t len) {
		return ctx->NotifyAuthenticated(std::string_view(public_key, len));
		}

		void adbd_auth_notify_disconnect(AdbdAuthContext* ctx, uint64_t id) {
		return ctx->NotifyDisconnected(id);
		}

		void adbd_auth_prompt_user(AdbdAuthContext* ctx, const char* public_key, size_t len,
		void* arg) {
		ctx->PromptUser(std::string_view(public_key, len), arg);
		}

		bool adbd_auth_supports_feature(AdbdAuthFeature) {
		return false;
		}

libs/adbd_auth/include/adbd_auth.h

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		#pragma once

		/*
		* 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 <stdbool.h>
		#include <stdint.h>
		#include <sys/types.h>

		extern "C" {

		struct AdbdAuthCallbacksV1 {
		// Callback for a successful user authorization.
		void (key_authorized)(void arg, uint64_t id);
		};

		struct AdbdAuthCallbacks {
		uint32_t version;
		union {
		AdbdAuthCallbacksV1 v1;
		} callbacks;
		};

		struct AdbdAuthContext;

		AdbdAuthContext* adbd_auth_new(AdbdAuthCallbacks* callbacks);
		void adbd_auth_delete(AdbdAuthContext* ctx);

		void adbd_auth_run(AdbdAuthContext* ctx);

		// Iterate through the list of authorized public keys.
		// Return false from the callback to stop iteration.
		void adbd_auth_get_public_keys(AdbdAuthContext* ctx,
		bool (callback)(const char public_key, size_t len, void* arg),
		void* arg);

		// Let system_server know that a key has been successfully used for authentication.
		uint64_t adbd_auth_notify_auth(AdbdAuthContext* ctx, const char* public_key, size_t len);

		// Let system_server know that a connection has been closed.
		void adbd_auth_notify_disconnect(AdbdAuthContext* ctx, uint64_t id);

		// Prompt the user to authorize a public key.
		// When this happens, a callback will be run on the auth thread with the result.
		void adbd_auth_prompt_user(AdbdAuthContext* ctx, const char* public_key, size_t len, void* arg);

		enum AdbdAuthFeature {
		};

		bool adbd_auth_supports_feature(AdbdAuthFeature f);

		}

libs/adbd_auth/libadbd_auth.map.txt

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		LIBADBD_AUTH {
		global:
		adbd_auth_new; # apex
		adbd_auth_delete; # apex
		adbd_auth_run; # apex
		adbd_auth_get_public_keys; #apex
		adbd_auth_notify_auth; # apex
		adbd_auth_notify_disconnect; # apex
		adbd_auth_prompt_user; # apex
		adbd_auth_supports_feature; # apex
		local:
		*;
		};