[adbwifi] Add pairing_auth library. (340a5e86) · Commits · e / os / android_system_core

adb/pairing_auth/Android.bp

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		// Copyright (C) 2020 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_defaults {
		name: "libadb_pairing_auth_defaults",
		cflags: [
		"-Wall",
		"-Wextra",
		"-Wthread-safety",
		"-Werror",
		],

		compile_multilib: "both",

		srcs: [
		"aes_128_gcm.cpp",
		"pairing_auth.cpp",
		],
		target: {
		android: {
		version_script: "libadb_pairing_auth.map.txt",
		},
		windows: {
		compile_multilib: "first",
		enabled: true,
		},
		},
		export_include_dirs: ["include"],

		visibility: [
		"//art:__subpackages__",
		"//system/core/adb:__subpackages__",
		],

		// libadb_pairing_auth doesn't need an embedded build number.
		use_version_lib: false,

		host_supported: true,
		recovery_available: true,

		stl: "libc++_static",

		static_libs: ["libbase"],
		shared_libs: [
		"libcrypto",
		"liblog",
		],
		}

		cc_library {
		name: "libadb_pairing_auth",
		defaults: ["libadb_pairing_auth_defaults"],

		apex_available: [
		"com.android.adbd",
		],

		stubs: {
		symbol_file: "libadb_pairing_auth.map.txt",
		versions: ["30"],
		},
		}

		// For running atest (b/147158681)
		cc_library_static {
		name: "libadb_pairing_auth_static",
		defaults: ["libadb_pairing_auth_defaults"],

		apex_available: [
		"//apex_available:platform",
		],
		}

adb/pairing_auth/aes_128_gcm.cpp

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		/*
		* Copyright (C) 2020 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 "adb/pairing/aes_128_gcm.h"

		#include <android-base/endian.h>
		#include <android-base/logging.h>

		#include <openssl/crypto.h>
		#include <openssl/evp.h>
		#include <openssl/hkdf.h>
		#include <openssl/rand.h>

		namespace adb {
		namespace pairing {

		namespace {
		static const size_t kHkdfKeyLength = 256;

		struct Header {
		uint32_t payload;
		uint8_t iv[AES_128_GCM_IV_SIZE];
		uint8_t tag[AES_128_GCM_TAG_SIZE];
		} __attribute__((packed));

		} // namespace

		// static
		const EVP_CIPHER* Aes128Gcm::cipher_ = EVP_aes_128_gcm();

		Aes128Gcm::Aes128Gcm(const uint8_t* key_material, size_t key_material_len) {
		CHECK(key_material);
		CHECK_NE(key_material_len, 0ul);
		context_.reset(EVP_CIPHER_CTX_new());
		CHECK(context_.get());

		// Start with a random number for our counter
		CHECK_EQ(RAND_bytes(counter_.data(), counter_.size()), 1);

		uint8_t key[kHkdfKeyLength] = {};
		uint8_t salt[64] = "this is the salt";
		uint8_t info[64] = "this is the info";
		CHECK_EQ(HKDF(key, sizeof(key), EVP_sha256(), key_material, key_material_len, salt,
		sizeof(salt), info, sizeof(info)),
		1);
		CHECK_EQ(AES_set_encrypt_key(key, sizeof(key), &aes_key_), 0);
		}

		int Aes128Gcm::Encrypt(const uint8_t* in, size_t in_len, uint8_t* out, size_t out_len) {
		if (out_len < EncryptedSize(in_len)) {
		LOG(ERROR) << "out buffer size (sz=" << out_len
		<< ") not big enough (sz=" << EncryptedSize(in_len) << ")";
		return -1;
		}
		auto& header = reinterpret_cast<Header>(out);
		// Place the IV in the header
		memcpy(header.iv, counter_.data(), counter_.size());
		int status = EVP_EncryptInit_ex(context_.get(), cipher_, nullptr,
		reinterpret_cast<const uint8_t*>(&aes_key_), counter_.data());
		counter_.Increase();
		if (status != 1) {
		return -1;
		}

		int cipherLen = 0;
		out += sizeof(header);
		status = EVP_EncryptUpdate(context_.get(), out, &cipherLen, in, in_len);
		if (status != 1 \|\| cipherLen < 0) {
		return -1;
		}

		// Padding is enabled by default, so EVP_EncryptFinal_ex will pad any
		// remaining partial data up to the block size.
		int padding = 0;
		status = EVP_EncryptFinal_ex(context_.get(), out + cipherLen, &padding);
		if (status != 1 \|\| padding < 0) {
		return -1;
		}

		// Place the tag in the header
		status = EVP_CIPHER_CTX_ctrl(context_.get(), EVP_CTRL_GCM_GET_TAG, sizeof(header.tag),
		header.tag);
		if (status != 1) {
		return -1;
		}
		// Place the payload size in the header
		uint32_t totalLen = sizeof(header) + cipherLen + padding;
		header.payload = htonl(static_cast<uint32_t>(cipherLen) + static_cast<uint32_t>(padding));
		return totalLen;
		}

		int Aes128Gcm::Decrypt(const uint8_t* in, size_t in_len, uint8_t* out, size_t out_len) {
		if (in_len < sizeof(Header)) {
		return 0;
		}
		if (out_len < DecryptedSize(in, in_len)) {
		return 0;
		}
		const auto& header = reinterpret_cast<const Header>(in);
		uint32_t payload = ntohl(header.payload);
		uint32_t expected_inlen = sizeof(Header) + payload;
		if (in_len < expected_inlen) {
		// Not enough data available
		return 0;
		}
		// Initialized with expected IV from header
		int status = EVP_DecryptInit_ex(context_.get(), cipher_, nullptr,
		reinterpret_cast<const uint8_t*>(&aes_key_), header.iv);
		if (status != 1) {
		return -1;
		}

		int decrypted_len = 0;
		status = EVP_DecryptUpdate(context_.get(), out, &decrypted_len, in + sizeof(header), payload);
		if (status != 1 \|\| decrypted_len < 0) {
		return -1;
		}

		// Set expected tag from header
		status = EVP_CIPHER_CTX_ctrl(context_.get(), EVP_CTRL_GCM_SET_TAG, sizeof(header.tag),
		const_cast<uint8_t*>(header.tag));
		if (status != 1) {
		return -1;
		}

		// This is the padding. It can be ignored.
		int len = 0;
		status = EVP_DecryptFinal_ex(context_.get(), out + decrypted_len, &len);
		if (status != 1) {
		LOG(ERROR) << "EVP_DecryptFinal_ex failed. Tag mismatch";
		return -1;
		}

		// Return the length without the padding.
		return decrypted_len;
		}

		size_t Aes128Gcm::EncryptedSize(size_t size) {
		// We need to account for block alignment of the encrypted data.
		// According to openssl.org/docs/man1.0.2/man3/EVP_EncryptUpdate.html,
		// "The amount of data written depends on the block alignment of the
		// encrypted data ..."
		// ".. the amount of data written may be anything from zero bytes to
		// (inl + cipher_block_size - 1) ..."
		const size_t cipher_block_size = EVP_CIPHER_block_size(cipher_);
		size_t padding = cipher_block_size - (size % cipher_block_size);
		if (padding != cipher_block_size) {
		size += padding;
		}
		return size + sizeof(Header);
		}

		size_t Aes128Gcm::DecryptedSize(const uint8_t* encrypted_data, size_t encrypted_size) {
		if (encrypted_size < sizeof(Header)) {
		// Not enough data yet
		return 0;
		}
		auto header = reinterpret_cast<const Header*>(encrypted_data);
		uint32_t payload = ntohl(header->payload);
		size_t total_size = payload + sizeof(Header);
		if (encrypted_size < total_size) {
		// There's enough data for the header but not enough data for the
		// payload. Indicate that there's not enough data for now.
		return 0;
		}
		return payload;
		}

		} // namespace pairing
		} // namespace adb

adb/pairing_auth/include/adb/pairing/aes_128_gcm.h

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		/*
		* Copyright (C) 2020 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.
		*/

		#pragma once

		#include <openssl/aes.h>
		#include <openssl/cipher.h>

		#include <stdint.h>

		#include "adb/pairing/counter.h"

		// This is the default size of the initialization vector (iv) for AES-128-GCM
		#define AES_128_GCM_IV_SIZE 12
		// This is the full tag size for AES-128-GCM
		#define AES_128_GCM_TAG_SIZE 16

		namespace adb {
		namespace pairing {

		class Aes128Gcm {
		public:
		explicit Aes128Gcm(const uint8_t* key_material, size_t key_material_len);

		// Encrypt a block of data in \|in\| of length \|in_len\|, this consumes all data
		// in \|in\| and places the encrypted data in \|out\| if \|out_len\| indicates that
		// there is enough space. The data contains information needed for
		// decryption that is specific to this implementation and is therefore only
		// suitable for decryption with this class.
		// The method returns the number of bytes placed in \|out\| on success and a
		// negative value if an error occurs.
		int Encrypt(const uint8_t* in, size_t in_len, uint8_t* out, size_t out_len);
		// Decrypt a block of data in \|in\| of length \|in_len\|, this consumes all data
		// in \|in_len\| bytes of data. The decrypted output is placed in the \|out\|
		// buffer of length \|out_len\|. On successful decryption the number of bytes in
		// \|out\| will be placed in \|out_len\|.
		// The method returns the number of bytes consumed from the \|in\| buffer. If
		// there is not enough data available in \|in\| the method returns zero. If
		// an error occurs the method returns a negative value.
		int Decrypt(const uint8_t* in, size_t in_len, uint8_t* out, size_t out_len);

		// Return a safe amount of buffer storage needed to encrypt \|size\| bytes.
		size_t EncryptedSize(size_t size);
		// Return a safe amount of buffer storage needed to decrypt the encrypted
		// data in \|encrypted_data\| which is of length \|encrypted_size\|. Returns 0 if
		// there is not enough data available to determine the required size.
		size_t DecryptedSize(const uint8_t* encrypted_data, size_t encrypted_size);

		static const EVP_CIPHER* cipher_;

		private:
		bssl::UniquePtr<EVP_CIPHER_CTX> context_;
		AES_KEY aes_key_;
		// We're going to use this counter for our iv so that it never repeats
		Counter<AES_128_GCM_IV_SIZE> counter_;
		};

		} // namespace pairing
		} // namespace adb

adb/pairing_auth/include/adb/pairing/counter.h

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		/*
		* Copyright (C) 2020 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.
		*/

		#pragma once

		#include <stddef.h>
		#include <stdint.h>

		namespace adb {
		namespace pairing {

		template <size_t N>
		class Counter {
		public:
		void Increase() {
		for (size_t i = sizeof(counter_) - 1; i < sizeof(counter_); --i) {
		if (++counter_[i] != 0) {
		break;
		}
		}
		}

		uint8_t* data() { return counter_; }
		const uint8_t* data() const { return counter_; }

		constexpr size_t size() const { return sizeof(counter_); }

		uint8_t& operator[](size_t index) { return counter_[index]; }
		const uint8_t& operator[](size_t index) const { return counter_[index]; }

		private:
		uint8_t counter_[N];
		};

		} // namespace pairing
		} // namespace adb

adb/pairing_auth/include/adb/pairing/pairing_auth.h

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		/*
		* Copyright (C) 2020 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.
		*/

		#pragma once

		#include <stddef.h>
		#include <stdint.h>
		#include <sys/cdefs.h>

		#if !defined(__INTRODUCED_IN)
		#define __INTRODUCED_IN(__api_level) /* nothing */
		#endif

		__BEGIN_DECLS
		#if !defined(__ANDROID__) \|\| __ANDROID_API__ >= 30

		/**
		* PairingAuthCtx is a wrapper around the SPAKE2 protocol + cipher initialization
		* for encryption. On construction, the \|password\| will be used to generate a
		* SPAKE2 message. Each peer will exchange the messages in \|pairing_auth_get_msg\|
		* to initialize their ciphers in \|pairing_auth_init_cipher\|. If both peers used the
		* same \|password\|, then both sides will be able to decrypt each other's messages.
		*
		* On creation of a PairingAuthCtx, \|pairing_auth_init_cipher\| prior to using
		* the encrypt and decrypt APIs. Furthermore, you can only initialize the cipher
		* once.
		*
		* See pairing_auth_test.cpp for example usage.
		*
		*/
		struct PairingAuthCtx;
		typedef struct PairingAuthCtx PairingAuthCtx;

		/**
		* Creates a new PairingAuthCtx instance as the server.
		*
		* @param pswd the shared secret the server and client use to authenticate each
		* other. Will abort if null.
		* @param len the length of the pswd in bytes. Will abort if 0.
		* @return a new PairingAuthCtx server instance. Caller is responsible for
		* destroying the context via #pairing_auth_destroy.
		*/
		PairingAuthCtx* pairing_auth_server_new(const uint8_t* pswd, size_t len) __INTRODUCED_IN(30);

		/**
		* Creates a new PairingAuthCtx instance as the client.
		*
		* @param pswd the shared secret the server and client use to authenticate each
		* other. Will abort if null.
		* @param len the length of the pswd in bytes. Will abort if 0.
		* @return a new PairingAuthCtx client instance. Caller is responsible for
		* destroying the context via #pairing_auth_destroy.
		*/
		PairingAuthCtx* pairing_auth_client_new(const uint8_t* pswd, size_t len) __INTRODUCED_IN(30);

		/**
		* Destroys the PairingAuthCtx.
		*
		* @param ctx the PairingAuthCtx instance to destroy. Will abort if null.
		*/
		void pairing_auth_destroy(PairingAuthCtx* ctx) __INTRODUCED_IN(30);

		/**
		* Returns the exact size of the SPAKE2 msg.
		*
		* Use this size as the buffer size when retrieving the message via
		* #pairing_auth_get_msg.
		*
		* @param ctx the PairingAuthCtx instance. Will abort if null.
		* @return the size of the SPAKE2 message in bytes. This is guaranteed to be > 0.
		*/
		size_t pairing_auth_msg_size(PairingAuthCtx* ctx) __INTRODUCED_IN(30);

		/**
		* Writes the SPAKE2 message to exchange with the other party to \|out_buf\|.
		*
		* This is guaranteed to write a valid message to \|out_buf\|. Use #pairing_auth_msg_size
		* to get the size the \|out_buf\| should be. The SPAKE2 messages will be used to
		* initialize the cipher for encryption/decryption (see #pairing_auth_init_cipher).
		*
		* @param ctx the PairingAuthCtx instance. Will abort if null.
		* @param out_buf the buffer the message is written to. The buffer is assumed to
		* be have at least #pairing_auth_msg_size size. Will abort if
		* out_buf is null.
		*/
		void pairing_auth_get_spake2_msg(PairingAuthCtx* ctx, uint8_t* out_buf) __INTRODUCED_IN(30);

		/**
		* Processes the peer's \|their_msg\| and attempts to initialize the cipher for
		* encryption.
		*
		* You can only call this method ONCE with a non-empty \|msg\|, regardless of success
		* or failure. On success, you can use the #pairing_auth_decrypt and #pairing_auth_encrypt
		* methods to exchange any further information securely. On failure, this
		* PairingAuthCtx instance has no more purpose and should be destroyed.
		*
		* @param ctx the PairingAuthCtx instance. Will abort if null.
		* @param their_msg the peer's SPAKE2 msg. See #pairing_auth_get_msg. Will abort
		* if null.
		* @param msg_len the length of their_msg in bytes. Will abort if 0.
		* @return true iff the client and server used the same password when creating
		* the PairingAuthCtx. See
		* https: *commondatastorage.googleapis.com/chromium-boringssl-docs/curve25519.h.html#SPAKE2
		* for more details on the SPAKE2 protocol.
		*/
		bool pairing_auth_init_cipher(PairingAuthCtx* ctx, const uint8_t* their_msg, size_t msg_len)
		__INTRODUCED_IN(30);

		/**
		* Returns a safe buffer size for encrypting data of a certain size.
		*
		* IMPORTANT: This will abort if either #pairing_auth_init_cipher was not called
		* or #pairing_auth_init_cipher failed.
		*
		* @param ctx the PairingAuthCtx instance. Will abort if null.
		* @param len the size of the message wanting to encrypt in bytes.
		* @return the minimum buffer size, in bytes, to hold an encrypted message of size len. See
		* #pairing_auth_encrypt for usage.
		*/
		size_t pairing_auth_safe_encrypted_size(PairingAuthCtx* ctx, size_t len) __INTRODUCED_IN(30);

		/**
		* Encrypts input data and writes the encrypted data into a user-provided buffer.
		*
		* IMPORTANT: This will abort if either #pairing_auth_init_cipher was not called
		* or #pairing_auth_init_cipher failed.
		*
		* @param ctx the PairingAuthCtx instance. Will abort if null.
		* @param inbuf the buffer containing the data to encrypt. Will abort if null.
		* @param inlen the size of inbuf in bytes. Will abort if 0.
		* @param outbuf the buffer to write the encrypted data to. Will abort if null
		* @param outlen the size of outbuf in bytes. See #pairing_auth_safe_encrypted_size.
		* @return true if all the data was encrypted and written to outbuf, false
		* otherwise.
		*/
		bool pairing_auth_encrypt(PairingAuthCtx* ctx, const uint8_t* inbuf, size_t inlen, uint8_t* outbuf,
		size_t* outlen) __INTRODUCED_IN(30);

		/**
		* Returns a safe buffer size for decrypting data of a certain size.
		*
		* IMPORTANT: This will abort if either #pairing_auth_init_cipher was not called
		* or #pairing_auth_init_cipher failed.
		*
		* @param ctx the PairingAuthCtx instance. Will abort if null.
		* @param buf the buffer containing the encrypted data. Will abort if null.
		* @param len the size of the buf in bytes. Will abort if 0.
		* @return the minimum buffer size, in bytes, to hold a decrypted message of size len. See
		* #pairing_auth_decrypt for usage.
		*/
		size_t pairing_auth_safe_decrypted_size(PairingAuthCtx* ctx, const uint8_t* buf, size_t len)
		__INTRODUCED_IN(30);

		/**
		* Decrypts input data and writes the decrypted data into a user-provided buffer.
		*
		* IMPORTANT: This will abort if either #pairing_auth_init_cipher was not called
		* or #pairing_auth_init_cipher failed.
		*
		* @param ctx the PairingAuthCtx instance. Will abort if null.
		* @param inbuf the buffer containing the data to decrypt. Will abort if null.
		* @param inlen the size of inbuf in bytes. WIll abort if 0.
		* @param outbuf the buffer to write the decrypted data to. Will abort if null.
		* @param outlen the size of outbuf in bytes. See #pairing_auth_safe_decrypted_size.
		* Will abort if 0.
		* @return true if all the data was decrypted and written to outbuf, false
		* otherwise.
		*/
		bool pairing_auth_decrypt(PairingAuthCtx* ctx, const uint8_t* inbuf, size_t inlen, uint8_t* outbuf,
		size_t* outlen) __INTRODUCED_IN(30);

		#endif //!__ANDROID__ \|\| __ANDROID_API__ >= 30
		__END_DECLS