keystore.c

linux 内核源代码

	memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
	       auth_tok->session_key.decrypted_key_size);
	crypt_stat->key_size = auth_tok->session_key.decrypted_key_size;
	rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher, cipher_code);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Cipher code [%d] is invalid\n",
				cipher_code)
		goto out;
	}
	crypt_stat->flags |= ECRYPTFS_KEY_VALID;
	if (ecryptfs_verbosity > 0) {
		ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
		ecryptfs_dump_hex(crypt_stat->key,
				  crypt_stat->key_size);
	}
out:
	if (msg)
		kfree(msg);
	return rc;
}

static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
{
	struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
	struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;

	list_for_each_entry_safe(auth_tok_list_item, auth_tok_list_item_tmp,
				 auth_tok_list_head, list) {
		list_del(&auth_tok_list_item->list);
		kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
				auth_tok_list_item);
	}
}

struct kmem_cache *ecryptfs_auth_tok_list_item_cache;

/**
 * parse_tag_1_packet
 * @crypt_stat: The cryptographic context to modify based on packet contents
 * @data: The raw bytes of the packet.
 * @auth_tok_list: eCryptfs parses packets into authentication tokens;
 *                 a new authentication token will be placed at the
 *                 end of this list for this packet.
 * @new_auth_tok: Pointer to a pointer to memory that this function
 *                allocates; sets the memory address of the pointer to
 *                NULL on error. This object is added to the
 *                auth_tok_list.
 * @packet_size: This function writes the size of the parsed packet
 *               into this memory location; zero on error.
 * @max_packet_size: The maximum allowable packet size
 *
 * Returns zero on success; non-zero on error.
 */
static int
parse_tag_1_packet(struct ecryptfs_crypt_stat *crypt_stat,
		   unsigned char *data, struct list_head *auth_tok_list,
		   struct ecryptfs_auth_tok **new_auth_tok,
		   size_t *packet_size, size_t max_packet_size)
{
	size_t body_size;
	struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
	size_t length_size;
	int rc = 0;

	(*packet_size) = 0;
	(*new_auth_tok) = NULL;
	/**
	 * This format is inspired by OpenPGP; see RFC 2440
	 * packet tag 1
	 *
	 * Tag 1 identifier (1 byte)
	 * Max Tag 1 packet size (max 3 bytes)
	 * Version (1 byte)
	 * Key identifier (8 bytes; ECRYPTFS_SIG_SIZE)
	 * Cipher identifier (1 byte)
	 * Encrypted key size (arbitrary)
	 *
	 * 12 bytes minimum packet size
	 */
	if (unlikely(max_packet_size < 12)) {
		printk(KERN_ERR "Invalid max packet size; must be >=12\n");
		rc = -EINVAL;
		goto out;
	}
	if (data[(*packet_size)++] != ECRYPTFS_TAG_1_PACKET_TYPE) {
		printk(KERN_ERR "Enter w/ first byte != 0x%.2x\n",
		       ECRYPTFS_TAG_1_PACKET_TYPE);
		rc = -EINVAL;
		goto out;
	}
	/* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
	 * at end of function upon failure */
	auth_tok_list_item =
		kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache,
				  GFP_KERNEL);
	if (!auth_tok_list_item) {
		printk(KERN_ERR "Unable to allocate memory\n");
		rc = -ENOMEM;
		goto out;
	}
	(*new_auth_tok) = &auth_tok_list_item->auth_tok;
	rc = parse_packet_length(&data[(*packet_size)], &body_size,
				 &length_size);
	if (rc) {
		printk(KERN_WARNING "Error parsing packet length; "
		       "rc = [%d]\n", rc);
		goto out_free;
	}
	if (unlikely(body_size < (ECRYPTFS_SIG_SIZE + 2))) {
		printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
		rc = -EINVAL;
		goto out_free;
	}
	(*packet_size) += length_size;
	if (unlikely((*packet_size) + body_size > max_packet_size)) {
		printk(KERN_WARNING "Packet size exceeds max\n");
		rc = -EINVAL;
		goto out_free;
	}
	if (unlikely(data[(*packet_size)++] != 0x03)) {
		printk(KERN_WARNING "Unknown version number [%d]\n",
		       data[(*packet_size) - 1]);
		rc = -EINVAL;
		goto out_free;
	}
	ecryptfs_to_hex((*new_auth_tok)->token.private_key.signature,
			&data[(*packet_size)], ECRYPTFS_SIG_SIZE);
	*packet_size += ECRYPTFS_SIG_SIZE;
	/* This byte is skipped because the kernel does not need to
	 * know which public key encryption algorithm was used */
	(*packet_size)++;
	(*new_auth_tok)->session_key.encrypted_key_size =
		body_size - (ECRYPTFS_SIG_SIZE + 2);
	if ((*new_auth_tok)->session_key.encrypted_key_size
	    > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
		printk(KERN_WARNING "Tag 1 packet contains key larger "
		       "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES");
		rc = -EINVAL;
		goto out;
	}
	memcpy((*new_auth_tok)->session_key.encrypted_key,
	       &data[(*packet_size)], (body_size - (ECRYPTFS_SIG_SIZE + 2)));
	(*packet_size) += (*new_auth_tok)->session_key.encrypted_key_size;
	(*new_auth_tok)->session_key.flags &=
		~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
	(*new_auth_tok)->session_key.flags |=
		ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
	(*new_auth_tok)->token_type = ECRYPTFS_PRIVATE_KEY;
	(*new_auth_tok)->flags = 0;
	(*new_auth_tok)->session_key.flags &=
		~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
	(*new_auth_tok)->session_key.flags &=
		~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
	list_add(&auth_tok_list_item->list, auth_tok_list);
	goto out;
out_free:
	(*new_auth_tok) = NULL;
	memset(auth_tok_list_item, 0,
	       sizeof(struct ecryptfs_auth_tok_list_item));
	kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
			auth_tok_list_item);
out:
	if (rc)
		(*packet_size) = 0;
	return rc;
}

/**
 * parse_tag_3_packet
 * @crypt_stat: The cryptographic context to modify based on packet
 *              contents.
 * @data: The raw bytes of the packet.
 * @auth_tok_list: eCryptfs parses packets into authentication tokens;
 *                 a new authentication token will be placed at the end
 *                 of this list for this packet.
 * @new_auth_tok: Pointer to a pointer to memory that this function
 *                allocates; sets the memory address of the pointer to
 *                NULL on error. This object is added to the
 *                auth_tok_list.
 * @packet_size: This function writes the size of the parsed packet
 *               into this memory location; zero on error.
 * @max_packet_size: maximum number of bytes to parse
 *
 * Returns zero on success; non-zero on error.
 */
static int
parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
		   unsigned char *data, struct list_head *auth_tok_list,
		   struct ecryptfs_auth_tok **new_auth_tok,
		   size_t *packet_size, size_t max_packet_size)
{
	size_t body_size;
	struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
	size_t length_size;
	int rc = 0;

	(*packet_size) = 0;
	(*new_auth_tok) = NULL;
	/**
	 *This format is inspired by OpenPGP; see RFC 2440
	 * packet tag 3
	 *
	 * Tag 3 identifier (1 byte)
	 * Max Tag 3 packet size (max 3 bytes)
	 * Version (1 byte)
	 * Cipher code (1 byte)
	 * S2K specifier (1 byte)
	 * Hash identifier (1 byte)
	 * Salt (ECRYPTFS_SALT_SIZE)
	 * Hash iterations (1 byte)
	 * Encrypted key (arbitrary)
	 *
	 * (ECRYPTFS_SALT_SIZE + 7) minimum packet size
	 */
	if (max_packet_size < (ECRYPTFS_SALT_SIZE + 7)) {
		printk(KERN_ERR "Max packet size too large\n");
		rc = -EINVAL;
		goto out;
	}
	if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
		printk(KERN_ERR "First byte != 0x%.2x; invalid packet\n",
		       ECRYPTFS_TAG_3_PACKET_TYPE);
		rc = -EINVAL;
		goto out;
	}
	/* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
	 * at end of function upon failure */
	auth_tok_list_item =
	    kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache, GFP_KERNEL);
	if (!auth_tok_list_item) {
		printk(KERN_ERR "Unable to allocate memory\n");
		rc = -ENOMEM;
		goto out;
	}
	(*new_auth_tok) = &auth_tok_list_item->auth_tok;
	rc = parse_packet_length(&data[(*packet_size)], &body_size,
				 &length_size);
	if (rc) {
		printk(KERN_WARNING "Error parsing packet length; rc = [%d]\n",
		       rc);
		goto out_free;
	}
	if (unlikely(body_size < (ECRYPTFS_SALT_SIZE + 5))) {
		printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
		rc = -EINVAL;
		goto out_free;
	}
	(*packet_size) += length_size;
	if (unlikely((*packet_size) + body_size > max_packet_size)) {
		printk(KERN_ERR "Packet size exceeds max\n");
		rc = -EINVAL;
		goto out_free;
	}
	(*new_auth_tok)->session_key.encrypted_key_size =
		(body_size - (ECRYPTFS_SALT_SIZE + 5));
	if (unlikely(data[(*packet_size)++] != 0x04)) {
		printk(KERN_WARNING "Unknown version number [%d]\n",
		       data[(*packet_size) - 1]);
		rc = -EINVAL;
		goto out_free;
	}
	ecryptfs_cipher_code_to_string(crypt_stat->cipher,
				       (u16)data[(*packet_size)]);
	/* A little extra work to differentiate among the AES key
	 * sizes; see RFC2440 */
	switch(data[(*packet_size)++]) {
	case RFC2440_CIPHER_AES_192:
		crypt_stat->key_size = 24;
		break;
	default:
		crypt_stat->key_size =
			(*new_auth_tok)->session_key.encrypted_key_size;
	}
	ecryptfs_init_crypt_ctx(crypt_stat);
	if (unlikely(data[(*packet_size)++] != 0x03)) {
		printk(KERN_WARNING "Only S2K ID 3 is currently supported\n");
		rc = -ENOSYS;
		goto out_free;
	}
	/* TODO: finish the hash mapping */
	switch (data[(*packet_size)++]) {
	case 0x01: /* See RFC2440 for these numbers and their mappings */
		/* Choose MD5 */
		memcpy((*new_auth_tok)->token.password.salt,
		       &data[(*packet_size)], ECRYPTFS_SALT_SIZE);
		(*packet_size) += ECRYPTFS_SALT_SIZE;
		/* This conversion was taken straight from RFC2440 */
		(*new_auth_tok)->token.password.hash_iterations =
			((u32) 16 + (data[(*packet_size)] & 15))
				<< ((data[(*packet_size)] >> 4) + 6);
		(*packet_size)++;
		/* Friendly reminder:
		 * (*new_auth_tok)->session_key.encrypted_key_size =
		 *         (body_size - (ECRYPTFS_SALT_SIZE + 5)); */
		memcpy((*new_auth_tok)->session_key.encrypted_key,
		       &data[(*packet_size)],
		       (*new_auth_tok)->session_key.encrypted_key_size);
		(*packet_size) +=
			(*new_auth_tok)->session_key.encrypted_key_size;
		(*new_auth_tok)->session_key.flags &=
			~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
		(*new_auth_tok)->session_key.flags |=
			ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
		(*new_auth_tok)->token.password.hash_algo = 0x01; /* MD5 */
		break;
	default:
		ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
				"[%d]\n", data[(*packet_size) - 1]);
		rc = -ENOSYS;
		goto out_free;
	}
	(*new_auth_tok)->token_type = ECRYPTFS_PASSWORD;
	/* TODO: Parametarize; we might actually want userspace to
	 * decrypt the session key. */
	(*new_auth_tok)->session_key.flags &=
			    ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
	(*new_auth_tok)->session_key.flags &=
			    ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
	list_add(&auth_tok_list_item->list, auth_tok_list);
	goto out;
out_free:
	(*new_auth_tok) = NULL;
	memset(auth_tok_list_item, 0,
	       sizeof(struct ecryptfs_auth_tok_list_item));
	kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
			auth_tok_list_item);
out:
	if (rc)
		(*packet_size) = 0;
	return rc;
}

/**
 * parse_tag_11_packet
 * @data: The raw bytes of the packet
 * @contents: This function writes the data contents of the literal
 *            packet into this memory location
 * @max_contents_bytes: The maximum number of bytes that this function
 *                      is allowed to write into contents
 * @tag_11_contents_size: This function writes the size of the parsed
 *                        contents into this memory location; zero on
 *                        error
 * @packet_size: This function writes the size of the parsed packet
 *               into this memory location; zero on error
 * @max_packet_size: maximum number of bytes to parse
 *
 * Returns zero on success; non-zero on error.
 */
static int
parse_tag_11_packet(unsigned char *data, unsigned char *contents,
		    size_t max_contents_bytes, size_t *tag_11_contents_size,
		    size_t *packet_size, size_t max_packet_size)
{
	size_t body_size;
	size_t length_size;
	int rc = 0;

	(*packet_size) = 0;
	(*tag_11_contents_size) = 0;
	/* This format is inspired by OpenPGP; see RFC 2440
	 * packet tag 11
	 *
	 * Tag 11 identifier (1 byte)
	 * Max Tag 11 packet size (max 3 bytes)
	 * Binary format specifier (1 byte)
	 * Filename length (1 byte)
	 * Filename ("_CONSOLE") (8 bytes)
	 * Modification date (4 bytes)
	 * Literal data (arbitrary)
	 *
	 * We need at least 16 bytes of data for the packet to even be
	 * valid.
	 */
	if (max_packet_size < 16) {
		printk(KERN_ERR "Maximum packet size too small\n");
		rc = -EINVAL;
		goto out;
	}
	if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
		printk(KERN_WARNING "Invalid tag 11 packet format\n");
		rc = -EINVAL;
		goto out;
	}
	rc = parse_packet_length(&data[(*packet_size)], &body_size,
				 &length_size);
	if (rc) {
		printk(KERN_WARNING "Invalid tag 11 packet format\n");
		goto out;
	}
	if (body_size < 14) {
		printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
		rc = -EINVAL;
		goto out;
	}
	(*packet_size) += length_size;
	(*tag_11_contents_size) = (body_size - 14);
	if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
		printk(KERN_ERR "Packet size exceeds max\n");
		rc = -EINVAL;
		goto out;
	}
	if (data[(*packet_size)++] != 0x62) {
		printk(KERN_WARNING "Unrecognizable packet\n");
		rc = -EINVAL;
		goto out;
	}
	if (data[(*packet_size)++] != 0x08) {
		printk(KERN_WARNING "Unrecognizable packet\n");
		rc = -EINVAL;
		goto out;
	}
	(*packet_size) += 12; /* Ignore filename and modification date */
	memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size));
	(*packet_size) += (*tag_11_contents_size);
out:
	if (rc) {
		(*packet_size) = 0;
		(*tag_11_contents_size) = 0;
	}
	return rc;
}

static int
ecryptfs_find_global_auth_tok_for_sig(
	struct ecryptfs_global_auth_tok **global_auth_tok,
	struct ecryptfs_mount_crypt_stat *mount_crypt_stat, char *sig)
{
	struct ecryptfs_global_auth_tok *walker;
	int rc = 0;

	(*global_auth_tok) = NULL;
	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
	list_for_each_entry(walker,
			    &mount_crypt_stat->global_auth_tok_list,
			    mount_crypt_stat_list) {
		if (memcmp(walker->sig, sig, ECRYPTFS_SIG_SIZE_HEX) == 0) {
			(*global_auth_tok) = walker;
			goto out;
		}
	}
	rc = -EINVAL;
out:
	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
	return rc;
}

/**
 * ecryptfs_verify_version
 * @version: The version number to confirm
 *
 * Returns zero on good version; non-zero otherwise
 */
static int ecryptfs_verify_version(u16 version)
{
	int rc = 0;
	unsigned char major;
	unsigned char minor;

	major = ((version >> 8) & 0xFF);
	minor = (version & 0xFF);
	if (major != ECRYPTFS_VERSION_MAJOR) {
		ecryptfs_printk(KERN_ERR, "Major version number mismatch. "
				"Expected [%d]; got [%d]\n",
				ECRYPTFS_VERSION_MAJOR, major);
		rc = -EINVAL;
		goto out;
	}
	if (minor != ECRYPTFS_VERSION_MINOR) {
		ecryptfs_printk(KERN_ERR, "Minor version number mismatch. "
				"Expected [%d]; got [%d]\n",
				ECRYPTFS_VERSION_MINOR, minor);