keystore: add multi-user support. (4cff21f2) · Commits · e / os / platform_frameworks_native

cmds/keystore/keystore.c

0 → 100644

+532 −0

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		/*
		* Copyright (C) 2009 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 <stdio.h>
		#include <stdint.h>
		#include <string.h>
		#include <unistd.h>
		#include <signal.h>
		#include <errno.h>
		#include <dirent.h>
		#include <fcntl.h>
		#include <limits.h>
		#include <sys/types.h>
		#include <sys/socket.h>
		#include <sys/stat.h>
		#include <sys/time.h>
		#include <arpa/inet.h>

		#include <openssl/aes.h>
		#include <openssl/evp.h>
		#include <openssl/md5.h>

		#define LOG_TAG "keystore"
		#include <cutils/log.h>
		#include <cutils/sockets.h>
		#include <private/android_filesystem_config.h>

		#include "keystore.h"

		/* KeyStore is a secured storage for key-value pairs. In this implementation,
		* each file stores one key-value pair. Keys are encoded in file names, and
		* values are encrypted with checksums. The encryption key is protected by a
		* user-defined password. To keep things simple, buffers are always larger than
		* the maximum space we needed, so boundary checks on buffers are omitted. */

		#define KEY_SIZE 120
		#define VALUE_SIZE 32768
		#define PASSWORD_SIZE VALUE_SIZE

		/* Here is the encoding of keys. This is necessary in order to allow arbitrary
		* characters in keys. Characters in [0-~] are not encoded. Others are encoded
		* into two bytes. The first byte is one of [+-.] which represents the first
		* two bits of the character. The second byte encodes the rest of the bits into
		* [0-o]. Therefore in the worst case the length of a key gets doubled. Note
		* that Base64 cannot be used here due to the need of prefix match on keys. */

		static int encode_key(char out, uint8_t in, int length)
		{
		int i;
		for (i = length; i > 0; --i, ++in, ++out) {
		if (in >= '0' && in <= '~') {
		out = in;
		} else {
		out = '+' + (in >> 6);
		++out = '0' + (in & 0x3F);
		++length;
		}
		}
		*out = 0;
		return length;
		}

		static int decode_key(uint8_t out, char in, int length)
		{
		int i;
		for (i = 0; i < length; ++i, ++in, ++out) {
		if (in >= '0' && in <= '~') {
		out = in;
		} else {
		out = (in - '+') << 6;
		out \|= (++in - '0') & 0x3F;
		--length;
		}
		}
		*out = 0;
		return length;
		}

		/* Here is the protocol used in both requests and responses:
		* code [length_1 message_1 ... length_n message_n] end-of-file
		* where code is one byte long and lengths are unsigned 16-bit integers in
		* network order. Thus the maximum length of a message is 65535 bytes. */

		static int the_socket = -1;

		static int recv_code(int8_t *code)
		{
		return recv(the_socket, code, 1, 0) == 1;
		}

		static int recv_message(uint8_t *message, int length)
		{
		uint8_t bytes[2];
		if (recv(the_socket, &bytes[0], 1, 0) != 1 \|\|
		recv(the_socket, &bytes[1], 1, 0) != 1) {
		return -1;
		} else {
		int offset = bytes[0] << 8 \| bytes[1];
		if (length < offset) {
		return -1;
		}
		length = offset;
		offset = 0;
		while (offset < length) {
		int n = recv(the_socket, &message[offset], length - offset, 0);
		if (n <= 0) {
		return -1;
		}
		offset += n;
		}
		}
		return length;
		}

		static void send_code(int8_t code)
		{
		send(the_socket, &code, 1, 0);
		}

		static void send_message(uint8_t *message, int length)
		{
		uint16_t bytes = htons(length);
		send(the_socket, &bytes, 2, 0);
		send(the_socket, message, length, 0);
		}

		/* Here is the file format. Values are encrypted by AES CBC, and MD5 is used to
		* compute their checksums. To make the files portable, the length is stored in
		* network order. Note that the first four bytes are reserved for future use and
		* are always set to zero in this implementation. */

		static int the_entropy = -1;

		static struct __attribute__((packed)) {
		uint32_t reserved;
		uint8_t vector[AES_BLOCK_SIZE];
		uint8_t encrypted[0];
		uint8_t digest[MD5_DIGEST_LENGTH];
		uint8_t digested[0];
		int32_t length;
		uint8_t value[VALUE_SIZE + AES_BLOCK_SIZE];
		} blob;

		static int8_t encrypt_blob(char name, AES_KEY aes_key)
		{
		uint8_t vector[AES_BLOCK_SIZE];
		int length = blob.length;
		int fd;

		if (read(the_entropy, vector, AES_BLOCK_SIZE) != AES_BLOCK_SIZE) {
		return SYSTEM_ERROR;
		}

		length += blob.value - blob.digested;
		blob.length = htonl(blob.length);
		MD5(blob.digested, length, blob.digest);

		length += blob.digested - blob.encrypted;
		length = (length + AES_BLOCK_SIZE - 1) / AES_BLOCK_SIZE * AES_BLOCK_SIZE;
		memcpy(vector, blob.vector, AES_BLOCK_SIZE);
		AES_cbc_encrypt(blob.encrypted, blob.encrypted, length, aes_key, vector,
		AES_ENCRYPT);

		blob.reserved = 0;
		length += blob.encrypted - (uint8_t *)&blob;

		fd = open(".tmp", O_WRONLY \| O_TRUNC \| O_CREAT, S_IRUSR \| S_IWUSR);
		if (fd == -1 \|\| write(fd, &blob, length) != length) {
		return SYSTEM_ERROR;
		}
		close(fd);
		return rename(".tmp", name) ? SYSTEM_ERROR : NO_ERROR;
		}

		static int8_t decrypt_blob(char name, AES_KEY aes_key)
		{
		int fd = open(name, O_RDONLY);
		int length;

		if (fd == -1) {
		return (errno == ENOENT) ? KEY_NOT_FOUND : SYSTEM_ERROR;
		}
		length = read(fd, &blob, sizeof(blob));
		close(fd);

		length -= blob.encrypted - (uint8_t *)&blob;
		if (length < blob.value - blob.encrypted \|\| length % AES_BLOCK_SIZE != 0) {
		return VALUE_CORRUPTED;
		}

		AES_cbc_encrypt(blob.encrypted, blob.encrypted, length, aes_key,
		blob.vector, AES_DECRYPT);
		length -= blob.digested - blob.encrypted;
		if (!memcmp(blob.digest, MD5(blob.digested, length, NULL),
		MD5_DIGEST_LENGTH)) {
		return VALUE_CORRUPTED;
		}

		length -= blob.value - blob.digested;
		blob.length = ntohl(blob.length);
		return (length < blob.length) ? VALUE_CORRUPTED : NO_ERROR;
		}

		/* Here are the actions. Each of them is a function without arguments. All
		* information is defined in global variables, which are set properly before
		* performing an action. The number of parameters required by each action is
		* fixed and defined in a table. Note that the lengths of parameters are checked
		* when they are received, so boundary checks on parameters are omitted. */

		#define MAX_PARAM 2
		#define MAX_RETRY 4

		static uid_t uid = -1;
		static int8_t state = UNINITIALIZED;
		static int8_t retry = MAX_RETRY;

		static struct {
		int length;
		uint8_t value[VALUE_SIZE];
		} params[MAX_PARAM];

		static AES_KEY encryption_key;
		static AES_KEY decryption_key;

		static int8_t test()
		{
		return state;
		}

		static int8_t get()
		{
		char name[NAME_MAX];
		int n = sprintf(name, "%u_", uid);
		encode_key(&name[n], params[0].value, params[0].length);
		n = decrypt_blob(name, &decryption_key);
		if (n != NO_ERROR) {
		return n;
		}
		send_code(NO_ERROR);
		send_message(blob.value, blob.length);
		return -NO_ERROR;
		}

		static int8_t insert()
		{
		char name[NAME_MAX];
		int n = sprintf(name, "%u_", uid);
		encode_key(&name[n], params[0].value, params[0].length);
		blob.length = params[1].length;
		memcpy(blob.value, params[1].value, params[1].length);
		return encrypt_blob(name, &encryption_key);
		}

		static int8_t delete()
		{
		char name[NAME_MAX];
		int n = sprintf(name, "%u_", uid);
		encode_key(&name[n], params[0].value, params[0].length);
		return (unlink(name) && errno != ENOENT) ? SYSTEM_ERROR : NO_ERROR;
		}

		static int8_t exist()
		{
		char name[NAME_MAX];
		int n = sprintf(name, "%u_", uid);
		encode_key(&name[n], params[0].value, params[0].length);
		if (access(name, R_OK) == -1) {
		return (errno != ENOENT) ? SYSTEM_ERROR : KEY_NOT_FOUND;
		}
		return NO_ERROR;
		}

		static int8_t scan()
		{
		DIR *dir = opendir(".");
		struct dirent *file;
		char name[NAME_MAX];
		int n;

		if (!dir) {
		return SYSTEM_ERROR;
		}
		n = sprintf(name, "%u_", uid);
		n += encode_key(&name[n], params[0].value, params[0].length);
		send_code(NO_ERROR);
		while ((file = readdir(dir)) != NULL) {
		if (!strncmp(name, file->d_name, n)) {
		char *p = &file->d_name[n];
		params[0].length = decode_key(params[0].value, p, strlen(p));
		send_message(params[0].value, params[0].length);
		}
		}
		closedir(dir);
		return -NO_ERROR;
		}

		static int8_t reset()
		{
		DIR *dir = opendir(".");
		struct dirent *file;

		memset(&encryption_key, 0, sizeof(encryption_key));
		memset(&decryption_key, 0, sizeof(decryption_key));
		state = UNINITIALIZED;
		retry = MAX_RETRY;

		if (!dir) {
		return SYSTEM_ERROR;
		}
		while ((file = readdir(dir)) != NULL) {
		if (strcmp(".", file->d_name) \|\| strcmp("..", file->d_name)) {
		unlink(file->d_name);
		}
		}
		closedir(dir);
		return UNINITIALIZED;
		}

		#define MASTER_KEY_FILE ".masterkey"
		#define MASTER_KEY_SIZE 16

		static void generate_key(uint8_t key, uint8_t password, int length)
		{
		PKCS5_PBKDF2_HMAC_SHA1((char )password, length, (uint8_t )"keystore",
		sizeof("keystore"), 1024, MASTER_KEY_SIZE, key);
		}

		static int8_t password()
		{
		uint8_t key[MASTER_KEY_SIZE];
		AES_KEY aes_key;
		int n;

		if (state == UNINITIALIZED) {
		blob.length = MASTER_KEY_SIZE;
		if (read(the_entropy, blob.value, MASTER_KEY_SIZE) != MASTER_KEY_SIZE) {
		return SYSTEM_ERROR;
		}
		} else {
		generate_key(key, params[0].value, params[0].length);
		AES_set_decrypt_key(key, MASTER_KEY_SIZE * 8, &aes_key);
		n = decrypt_blob(MASTER_KEY_FILE, &aes_key);
		if (n == SYSTEM_ERROR) {
		return SYSTEM_ERROR;
		}
		if (n != NO_ERROR \|\| blob.length != MASTER_KEY_SIZE) {
		if (retry <= 0) {
		return reset();
		}
		return WRONG_PASSWORD + --retry;
		}
		}

		if (params[1].length == -1) {
		memcpy(key, blob.value, MASTER_KEY_SIZE);
		} else {
		generate_key(key, params[1].value, params[1].length);
		AES_set_encrypt_key(key, MASTER_KEY_SIZE * 8, &aes_key);
		memcpy(key, blob.value, MASTER_KEY_SIZE);
		n = encrypt_blob(MASTER_KEY_FILE, &aes_key);
		}

		if (n == NO_ERROR) {
		AES_set_encrypt_key(key, MASTER_KEY_SIZE * 8, &encryption_key);
		AES_set_decrypt_key(key, MASTER_KEY_SIZE * 8, &decryption_key);
		state = NO_ERROR;
		retry = MAX_RETRY;
		}
		return n;
		}

		static int8_t lock()
		{
		memset(&encryption_key, 0, sizeof(encryption_key));
		memset(&decryption_key, 0, sizeof(decryption_key));
		state = LOCKED;
		return LOCKED;
		}

		static int8_t unlock()
		{
		params[1].length = -1;
		return password();
		}

		/* Here are the permissions, actions, users, and the main function. */

		enum perm {
		TEST = 1,
		GET = 2,
		INSERT = 4,
		DELETE = 8,
		EXIST = 16,
		SCAN = 32,
		RESET = 64,
		PASSWORD = 128,
		LOCK = 256,
		UNLOCK = 512,
		};

		static struct action {
		int8_t (*run)();
		int8_t code;
		int8_t state;
		uint32_t perm;
		int lengths[MAX_PARAM];
		} actions[] = {
		{test, 't', 0, TEST, {0}},
		{get, 'g', NO_ERROR, GET, {KEY_SIZE}},
		{insert, 'i', NO_ERROR, INSERT, {KEY_SIZE, VALUE_SIZE}},
		{delete, 'd', NO_ERROR, DELETE, {KEY_SIZE}},
		{exist, 'e', NO_ERROR, EXIST, {KEY_SIZE}},
		{scan, 's', NO_ERROR, SCAN, {KEY_SIZE}},
		{reset, 'r', 0, RESET, {0}},
		{password, 'p', 0, PASSWORD, {PASSWORD_SIZE, PASSWORD_SIZE}},
		{lock, 'l', NO_ERROR, LOCK, {0}},
		{unlock, 'u', LOCKED, UNLOCK, {PASSWORD_SIZE}},
		{NULL, 0 , 0, 0, {0}},
		};

		static struct user {
		uid_t uid;
		uid_t euid;
		uint32_t perms;
		} users[] = {
		{AID_SYSTEM, 0, ~GET},
		{AID_VPN, AID_SYSTEM, GET},
		{AID_WIFI, AID_SYSTEM, GET},
		{0, 0, TEST \| GET \| INSERT \| DELETE \| EXIST \| SCAN},
		};

		static int8_t process(int8_t code) {
		struct user *user = users;
		struct action *action = actions;
		int i;

		while (user->uid && user->uid != uid) {
		++user;
		}
		while (action->code && action->code != code) {
		++action;
		}
		if (!action->code) {
		return UNDEFINED_ACTION;
		}
		if (!(action->perm & user->perms)) {
		return PERMISSION_DENIED;
		}
		if (action->state && action->state != state) {
		return state;
		}
		if (user->euid) {
		uid = user->euid;
		}
		for (i = 0; i < MAX_PARAM && action->lengths[i]; ++i) {
		params[i].length = recv_message(params[i].value, action->lengths[i]);
		if (params[i].length == -1) {
		return PROTOCOL_ERROR;
		}
		}
		return action->run();
		}

		#define RANDOM_DEVICE "/dev/urandom"

		int main(int argc, char **argv)
		{
		int control_socket = android_get_control_socket("keystore");
		if (argc < 2) {
		LOGE("A directory must be specified!");
		return 1;
		}
		if (chdir(argv[1]) == -1) {
		LOGE("chdir: %s: %s", argv[1], strerror(errno));
		return 1;
		}
		if ((the_entropy = open(RANDOM_DEVICE, O_RDONLY)) == -1) {
		LOGE("open: %s: %s", RANDOM_DEVICE, strerror(errno));
		return 1;
		}
		if (listen(control_socket, 3) == -1) {
		LOGE("listen: %s", strerror(errno));
		return 1;
		}

		signal(SIGPIPE, SIG_IGN);
		if (access(MASTER_KEY_FILE, R_OK) == 0) {
		state = LOCKED;
		}

		while ((the_socket = accept(control_socket, NULL, 0)) != -1) {
		struct timeval tv = {.tv_sec = 3};
		struct ucred cred;
		socklen_t size = sizeof(cred);
		int8_t request;

		setsockopt(the_socket, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
		setsockopt(the_socket, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));

		if (getsockopt(the_socket, SOL_SOCKET, SO_PEERCRED, &cred, &size)) {
		LOGW("getsockopt: %s", strerror(errno));
		} else if (recv_code(&request)) {
		int8_t old_state = state;
		int8_t response;
		uid = cred.uid;

		if ((response = process(request)) > 0) {
		send_code(response);
		response = -response;
		}

		LOGI("uid: %d action: %c -> %d state: %d -> %d retry: %d",
		cred.uid, request, -response, old_state, state, retry);
		}
		close(the_socket);
		}
		LOGE("accept: %s", strerror(errno));
		return 1;
		}

cmds/keystore/keystore.h

0 → 100644

+33 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2009 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.
		*/

		#ifndef __KEYSTORE_H__
		#define __KEYSTORE_H__

		enum response_code {
		NO_ERROR = 1,
		LOCKED = 2,
		UNINITIALIZED = 3,
		SYSTEM_ERROR = 4,
		PROTOCOL_ERROR = 5,
		PERMISSION_DENIED = 6,
		KEY_NOT_FOUND = 7,
		VALUE_CORRUPTED = 8,
		UNDEFINED_ACTION = 9,
		WRONG_PASSWORD = 10,
		};

		#endif

cmds/keystore/keystore_cli.c

0 → 100644

+97 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2009 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 <stdio.h>
		#include <stdint.h>
		#include <string.h>
		#include <sys/types.h>
		#include <sys/socket.h>

		#include <cutils/sockets.h>

		#include "keystore.h"

		char *responses[256] = {
		[NO_ERROR] = "No error",
		[LOCKED] = "Locked",
		[UNINITIALIZED] = "Uninitialized",
		[SYSTEM_ERROR] = "System error",
		[PROTOCOL_ERROR] = "Protocol error",
		[PERMISSION_DENIED] = "Permission denied",
		[KEY_NOT_FOUND] = "Key not found",
		[VALUE_CORRUPTED] = "Value corrupted",
		[UNDEFINED_ACTION] = "Undefined action",
		[WRONG_PASSWORD] = "Wrong password (last chance)",
		[WRONG_PASSWORD + 1] = "Wrong password (2 tries left)",
		[WRONG_PASSWORD + 2] = "Wrong password (3 tries left)",
		[WRONG_PASSWORD + 3] = "Wrong password (4 tries left)",
		};

		#define MAX_RESPONSE (WRONG_PASSWORD + 3)

		int main(int argc, char **argv)
		{
		uint8_t bytes[65536];
		uint8_t code;
		int sock, i;

		if (argc < 2) {
		printf("Usage: %s action [parameter ...]\n", argv[0]);
		return 0;
		}

		sock = socket_local_client("keystore",
		ANDROID_SOCKET_NAMESPACE_RESERVED, SOCK_STREAM);
		if (sock == -1) {
		puts("Failed to connect");
		return 1;
		}

		send(sock, argv[1], 1, 0);
		for (i = 2; i < argc; ++i) {
		uint16_t length = strlen(argv[i]);
		bytes[0] = length >> 8;
		bytes[1] = length;
		send(sock, &bytes, 2, 0);
		send(sock, argv[i], length, 0);
		}
		shutdown(sock, SHUT_WR);

		if (recv(sock, &code, 1, 0) != 1) {
		puts("Failed to receive");
		return 1;
		}
		printf("%d %s\n", code , responses[code] ? responses[code] : "Unknown");
		while ((i = recv(sock, &bytes[0], 1, 0)) == 1) {
		int length;
		int offset;
		if ((i = recv(sock, &bytes[1], 1, 0)) != 1) {
		puts("Failed to receive");
		return 1;
		}
		length = bytes[0] << 8 \| bytes[1];
		for (offset = 0; offset < length; offset += i) {
		i = recv(sock, &bytes[offset], length - offset, 0);
		if (i <= 0) {
		puts("Failed to receive");
		return 1;
		}
		}
		fwrite(bytes, 1, length, stdout);
		puts("");
		}
		return 0;
		}