keystore.c

linux 内核源代码

		rc = -EINVAL;
		goto out;
	}
out:
	return rc;
}

int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key,
				      struct ecryptfs_auth_tok **auth_tok,
				      char *sig)
{
	int rc = 0;

	(*auth_tok_key) = request_key(&key_type_user, sig, NULL);
	if (!(*auth_tok_key) || IS_ERR(*auth_tok_key)) {
		printk(KERN_ERR "Could not find key with description: [%s]\n",
		       sig);
		process_request_key_err(PTR_ERR(*auth_tok_key));
		rc = -EINVAL;
		goto out;
	}
	(*auth_tok) = ecryptfs_get_key_payload_data(*auth_tok_key);
	if (ecryptfs_verify_version((*auth_tok)->version)) {
		printk(KERN_ERR
		       "Data structure version mismatch. "
		       "Userspace tools must match eCryptfs "
		       "kernel module with major version [%d] "
		       "and minor version [%d]\n",
		       ECRYPTFS_VERSION_MAJOR,
		       ECRYPTFS_VERSION_MINOR);
		rc = -EINVAL;
		goto out;
	}
	if ((*auth_tok)->token_type != ECRYPTFS_PASSWORD
	    && (*auth_tok)->token_type != ECRYPTFS_PRIVATE_KEY) {
		printk(KERN_ERR "Invalid auth_tok structure "
		       "returned from key query\n");
		rc = -EINVAL;
		goto out;
	}
out:
	return rc;
}

/**
 * ecryptfs_find_auth_tok_for_sig
 * @auth_tok: Set to the matching auth_tok; NULL if not found
 * @crypt_stat: inode crypt_stat crypto context
 * @sig: Sig of auth_tok to find
 *
 * For now, this function simply looks at the registered auth_tok's
 * linked off the mount_crypt_stat, so all the auth_toks that can be
 * used must be registered at mount time. This function could
 * potentially try a lot harder to find auth_tok's (e.g., by calling
 * out to ecryptfsd to dynamically retrieve an auth_tok object) so
 * that static registration of auth_tok's will no longer be necessary.
 *
 * Returns zero on no error; non-zero on error
 */
static int
ecryptfs_find_auth_tok_for_sig(
	struct ecryptfs_auth_tok **auth_tok,
	struct ecryptfs_crypt_stat *crypt_stat, char *sig)
{
	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
		crypt_stat->mount_crypt_stat;
	struct ecryptfs_global_auth_tok *global_auth_tok;
	int rc = 0;

	(*auth_tok) = NULL;
	if (ecryptfs_find_global_auth_tok_for_sig(&global_auth_tok,
						  mount_crypt_stat, sig)) {
		struct key *auth_tok_key;

		rc = ecryptfs_keyring_auth_tok_for_sig(&auth_tok_key, auth_tok,
						       sig);
	} else
		(*auth_tok) = global_auth_tok->global_auth_tok;
	return rc;
}

/**
 * decrypt_passphrase_encrypted_session_key - Decrypt the session key with the given auth_tok.
 * @auth_tok: The passphrase authentication token to use to encrypt the FEK
 * @crypt_stat: The cryptographic context
 *
 * Returns zero on success; non-zero error otherwise
 */
static int
decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
					 struct ecryptfs_crypt_stat *crypt_stat)
{
	struct scatterlist dst_sg;
	struct scatterlist src_sg;
	struct mutex *tfm_mutex;
	struct blkcipher_desc desc = {
		.flags = CRYPTO_TFM_REQ_MAY_SLEEP
	};
	int rc = 0;

	sg_init_table(&dst_sg, 1);
	sg_init_table(&src_sg, 1);

	if (unlikely(ecryptfs_verbosity > 0)) {
		ecryptfs_printk(
			KERN_DEBUG, "Session key encryption key (size [%d]):\n",
			auth_tok->token.password.session_key_encryption_key_bytes);
		ecryptfs_dump_hex(
			auth_tok->token.password.session_key_encryption_key,
			auth_tok->token.password.session_key_encryption_key_bytes);
	}
	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
							crypt_stat->cipher);
	if (unlikely(rc)) {
		printk(KERN_ERR "Internal error whilst attempting to get "
		       "tfm and mutex for cipher name [%s]; rc = [%d]\n",
		       crypt_stat->cipher, rc);
		goto out;
	}
	rc = virt_to_scatterlist(auth_tok->session_key.encrypted_key,
				 auth_tok->session_key.encrypted_key_size,
				 &src_sg, 1);
	if (rc != 1) {
		printk(KERN_ERR "Internal error whilst attempting to convert "
			"auth_tok->session_key.encrypted_key to scatterlist; "
			"expected rc = 1; got rc = [%d]. "
		       "auth_tok->session_key.encrypted_key_size = [%d]\n", rc,
			auth_tok->session_key.encrypted_key_size);
		goto out;
	}
	auth_tok->session_key.decrypted_key_size =
		auth_tok->session_key.encrypted_key_size;
	rc = virt_to_scatterlist(auth_tok->session_key.decrypted_key,
				 auth_tok->session_key.decrypted_key_size,
				 &dst_sg, 1);
	if (rc != 1) {
		printk(KERN_ERR "Internal error whilst attempting to convert "
			"auth_tok->session_key.decrypted_key to scatterlist; "
			"expected rc = 1; got rc = [%d]\n", rc);
		goto out;
	}
	mutex_lock(tfm_mutex);
	rc = crypto_blkcipher_setkey(
		desc.tfm, auth_tok->token.password.session_key_encryption_key,
		crypt_stat->key_size);
	if (unlikely(rc < 0)) {
		mutex_unlock(tfm_mutex);
		printk(KERN_ERR "Error setting key for crypto context\n");
		rc = -EINVAL;
		goto out;
	}
	rc = crypto_blkcipher_decrypt(&desc, &dst_sg, &src_sg,
				      auth_tok->session_key.encrypted_key_size);
	mutex_unlock(tfm_mutex);
	if (unlikely(rc)) {
		printk(KERN_ERR "Error decrypting; rc = [%d]\n", rc);
		goto out;
	}
	auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
	memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
	       auth_tok->session_key.decrypted_key_size);
	crypt_stat->flags |= ECRYPTFS_KEY_VALID;
	if (unlikely(ecryptfs_verbosity > 0)) {
		ecryptfs_printk(KERN_DEBUG, "FEK of size [%d]:\n",
				crypt_stat->key_size);
		ecryptfs_dump_hex(crypt_stat->key,
				  crypt_stat->key_size);
	}
out:
	return rc;
}

/**
 * ecryptfs_parse_packet_set
 * @crypt_stat: The cryptographic context
 * @src: Virtual address of region of memory containing the packets
 * @ecryptfs_dentry: The eCryptfs dentry associated with the packet set
 *
 * Get crypt_stat to have the file's session key if the requisite key
 * is available to decrypt the session key.
 *
 * Returns Zero if a valid authentication token was retrieved and
 * processed; negative value for file not encrypted or for error
 * conditions.
 */
int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
			      unsigned char *src,
			      struct dentry *ecryptfs_dentry)
{
	size_t i = 0;
	size_t found_auth_tok;
	size_t next_packet_is_auth_tok_packet;
	struct list_head auth_tok_list;
	struct ecryptfs_auth_tok *matching_auth_tok;
	struct ecryptfs_auth_tok *candidate_auth_tok;
	char *candidate_auth_tok_sig;
	size_t packet_size;
	struct ecryptfs_auth_tok *new_auth_tok;
	unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
	struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
	size_t tag_11_contents_size;
	size_t tag_11_packet_size;
	int rc = 0;

	INIT_LIST_HEAD(&auth_tok_list);
	/* Parse the header to find as many packets as we can; these will be
	 * added the our &auth_tok_list */
	next_packet_is_auth_tok_packet = 1;
	while (next_packet_is_auth_tok_packet) {
		size_t max_packet_size = ((PAGE_CACHE_SIZE - 8) - i);

		switch (src[i]) {
		case ECRYPTFS_TAG_3_PACKET_TYPE:
			rc = parse_tag_3_packet(crypt_stat,
						(unsigned char *)&src[i],
						&auth_tok_list, &new_auth_tok,
						&packet_size, max_packet_size);
			if (rc) {
				ecryptfs_printk(KERN_ERR, "Error parsing "
						"tag 3 packet\n");
				rc = -EIO;
				goto out_wipe_list;
			}
			i += packet_size;
			rc = parse_tag_11_packet((unsigned char *)&src[i],
						 sig_tmp_space,
						 ECRYPTFS_SIG_SIZE,
						 &tag_11_contents_size,
						 &tag_11_packet_size,
						 max_packet_size);
			if (rc) {
				ecryptfs_printk(KERN_ERR, "No valid "
						"(ecryptfs-specific) literal "
						"packet containing "
						"authentication token "
						"signature found after "
						"tag 3 packet\n");
				rc = -EIO;
				goto out_wipe_list;
			}
			i += tag_11_packet_size;
			if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
				ecryptfs_printk(KERN_ERR, "Expected "
						"signature of size [%d]; "
						"read size [%d]\n",
						ECRYPTFS_SIG_SIZE,
						tag_11_contents_size);
				rc = -EIO;
				goto out_wipe_list;
			}
			ecryptfs_to_hex(new_auth_tok->token.password.signature,
					sig_tmp_space, tag_11_contents_size);
			new_auth_tok->token.password.signature[
				ECRYPTFS_PASSWORD_SIG_SIZE] = '\0';
			crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
			break;
		case ECRYPTFS_TAG_1_PACKET_TYPE:
			rc = parse_tag_1_packet(crypt_stat,
						(unsigned char *)&src[i],
						&auth_tok_list, &new_auth_tok,
						&packet_size, max_packet_size);
			if (rc) {
				ecryptfs_printk(KERN_ERR, "Error parsing "
						"tag 1 packet\n");
				rc = -EIO;
				goto out_wipe_list;
			}
			i += packet_size;
			crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
			break;
		case ECRYPTFS_TAG_11_PACKET_TYPE:
			ecryptfs_printk(KERN_WARNING, "Invalid packet set "
					"(Tag 11 not allowed by itself)\n");
			rc = -EIO;
			goto out_wipe_list;
			break;
		default:
			ecryptfs_printk(KERN_DEBUG, "No packet at offset "
					"[%d] of the file header; hex value of "
					"character is [0x%.2x]\n", i, src[i]);
			next_packet_is_auth_tok_packet = 0;
		}
	}
	if (list_empty(&auth_tok_list)) {
		printk(KERN_ERR "The lower file appears to be a non-encrypted "
		       "eCryptfs file; this is not supported in this version "
		       "of the eCryptfs kernel module\n");
		rc = -EINVAL;
		goto out;
	}
	/* auth_tok_list contains the set of authentication tokens
	 * parsed from the metadata. We need to find a matching
	 * authentication token that has the secret component(s)
	 * necessary to decrypt the EFEK in the auth_tok parsed from
	 * the metadata. There may be several potential matches, but
	 * just one will be sufficient to decrypt to get the FEK. */
find_next_matching_auth_tok:
	found_auth_tok = 0;
	list_for_each_entry(auth_tok_list_item, &auth_tok_list, list) {
		candidate_auth_tok = &auth_tok_list_item->auth_tok;
		if (unlikely(ecryptfs_verbosity > 0)) {
			ecryptfs_printk(KERN_DEBUG,
					"Considering cadidate auth tok:\n");
			ecryptfs_dump_auth_tok(candidate_auth_tok);
		}
		rc = ecryptfs_get_auth_tok_sig(&candidate_auth_tok_sig,
					       candidate_auth_tok);
		if (rc) {
			printk(KERN_ERR
			       "Unrecognized candidate auth tok type: [%d]\n",
			       candidate_auth_tok->token_type);
			rc = -EINVAL;
			goto out_wipe_list;
		}
		ecryptfs_find_auth_tok_for_sig(&matching_auth_tok, crypt_stat,
					       candidate_auth_tok_sig);
		if (matching_auth_tok) {
			found_auth_tok = 1;
			goto found_matching_auth_tok;
		}
	}
	if (!found_auth_tok) {
		ecryptfs_printk(KERN_ERR, "Could not find a usable "
				"authentication token\n");
		rc = -EIO;
		goto out_wipe_list;
	}
found_matching_auth_tok:
	if (candidate_auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
		memcpy(&(candidate_auth_tok->token.private_key),
		       &(matching_auth_tok->token.private_key),
		       sizeof(struct ecryptfs_private_key));
		rc = decrypt_pki_encrypted_session_key(candidate_auth_tok,
						       crypt_stat);
	} else if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD) {
		memcpy(&(candidate_auth_tok->token.password),
		       &(matching_auth_tok->token.password),
		       sizeof(struct ecryptfs_password));
		rc = decrypt_passphrase_encrypted_session_key(
			candidate_auth_tok, crypt_stat);
	}
	if (rc) {
		struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;

		ecryptfs_printk(KERN_WARNING, "Error decrypting the "
				"session key for authentication token with sig "
				"[%.*s]; rc = [%d]. Removing auth tok "
				"candidate from the list and searching for "
				"the next match.\n", candidate_auth_tok_sig,
				ECRYPTFS_SIG_SIZE_HEX, rc);
		list_for_each_entry_safe(auth_tok_list_item,
					 auth_tok_list_item_tmp,
					 &auth_tok_list, list) {
			if (candidate_auth_tok
			    == &auth_tok_list_item->auth_tok) {
				list_del(&auth_tok_list_item->list);
				kmem_cache_free(
					ecryptfs_auth_tok_list_item_cache,
					auth_tok_list_item);
				goto find_next_matching_auth_tok;
			}
		}
		BUG();
	}
	rc = ecryptfs_compute_root_iv(crypt_stat);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error computing "
				"the root IV\n");
		goto out_wipe_list;
	}
	rc = ecryptfs_init_crypt_ctx(crypt_stat);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error initializing crypto "
				"context for cipher [%s]; rc = [%d]\n",
				crypt_stat->cipher, rc);
	}
out_wipe_list:
	wipe_auth_tok_list(&auth_tok_list);
out:
	return rc;
}

static int
pki_encrypt_session_key(struct ecryptfs_auth_tok *auth_tok,
			struct ecryptfs_crypt_stat *crypt_stat,
			struct ecryptfs_key_record *key_rec)
{
	struct ecryptfs_msg_ctx *msg_ctx = NULL;
	char *netlink_payload;
	size_t netlink_payload_length;
	struct ecryptfs_message *msg;
	int rc;

	rc = write_tag_66_packet(auth_tok->token.private_key.signature,
				 ecryptfs_code_for_cipher_string(crypt_stat),
				 crypt_stat, &netlink_payload,
				 &netlink_payload_length);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet\n");
		goto out;
	}
	rc = ecryptfs_send_message(ecryptfs_transport, netlink_payload,
				   netlink_payload_length, &msg_ctx);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error sending netlink message\n");
		goto out;
	}
	rc = ecryptfs_wait_for_response(msg_ctx, &msg);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Failed to receive tag 67 packet "
				"from the user space daemon\n");
		rc = -EIO;
		goto out;
	}
	rc = parse_tag_67_packet(key_rec, msg);
	if (rc)
		ecryptfs_printk(KERN_ERR, "Error parsing tag 67 packet\n");
	kfree(msg);
out:
	if (netlink_payload)
		kfree(netlink_payload);
	return rc;
}
/**
 * write_tag_1_packet - Write an RFC2440-compatible tag 1 (public key) packet
 * @dest: Buffer into which to write the packet
 * @remaining_bytes: Maximum number of bytes that can be writtn
 * @auth_tok: The authentication token used for generating the tag 1 packet
 * @crypt_stat: The cryptographic context
 * @key_rec: The key record struct for the tag 1 packet
 * @packet_size: This function will write the number of bytes that end
 *               up constituting the packet; set to zero on error
 *
 * Returns zero on success; non-zero on error.
 */
static int
write_tag_1_packet(char *dest, size_t *remaining_bytes,
		   struct ecryptfs_auth_tok *auth_tok,
		   struct ecryptfs_crypt_stat *crypt_stat,
		   struct ecryptfs_key_record *key_rec, size_t *packet_size)
{
	size_t i;
	size_t encrypted_session_key_valid = 0;
	size_t packet_size_length;
	size_t max_packet_size;
	int rc = 0;

	(*packet_size) = 0;
	ecryptfs_from_hex(key_rec->sig, auth_tok->token.private_key.signature,
			  ECRYPTFS_SIG_SIZE);
	encrypted_session_key_valid = 0;
	for (i = 0; i < crypt_stat->key_size; i++)
		encrypted_session_key_valid |=
			auth_tok->session_key.encrypted_key[i];
	if (encrypted_session_key_valid) {
		memcpy(key_rec->enc_key,
		       auth_tok->session_key.encrypted_key,
		       auth_tok->session_key.encrypted_key_size);
		goto encrypted_session_key_set;
	}
	if (auth_tok->session_key.encrypted_key_size == 0)
		auth_tok->session_key.encrypted_key_size =
			auth_tok->token.private_key.key_size;
	rc = pki_encrypt_session_key(auth_tok, crypt_stat, key_rec);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Failed to encrypt session key "
				"via a pki");
		goto out;
	}
	if (ecryptfs_verbosity > 0) {
		ecryptfs_printk(KERN_DEBUG, "Encrypted key:\n");