static int drbd_adm_prepare()

in drbd/drbd_nl.c [159:301]

• 114 lines of code
• 37 McCabe index (conditional complexity)

static int drbd_adm_prepare(struct drbd_config_context *adm_ctx,
	struct sk_buff *skb, struct genl_info *info, unsigned flags)
{
	struct drbd_genlmsghdr *d_in = info->userhdr;
	const u8 cmd = info->genlhdr->cmd;
	int err;

	memset(adm_ctx, 0, sizeof(*adm_ctx));

	/* genl_rcv_msg only checks for CAP_NET_ADMIN on "GENL_ADMIN_PERM" :( */
	if (cmd != DRBD_ADM_GET_STATUS && !capable(CAP_NET_ADMIN))
	       return -EPERM;

	adm_ctx->reply_skb = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
	if (!adm_ctx->reply_skb) {
		err = -ENOMEM;
		goto fail;
	}

	adm_ctx->reply_dh = genlmsg_put_reply(adm_ctx->reply_skb,
					info, &drbd_genl_family, 0, cmd);
	/* put of a few bytes into a fresh skb of >= 4k will always succeed.
	 * but anyways */
	if (!adm_ctx->reply_dh) {
		err = -ENOMEM;
		goto fail;
	}

	adm_ctx->reply_dh->minor = d_in->minor;
	adm_ctx->reply_dh->ret_code = NO_ERROR;

	adm_ctx->volume = VOLUME_UNSPECIFIED;
	if (info->attrs[DRBD_NLA_CFG_CONTEXT]) {
		struct nlattr *nla;
		/* parse and validate only */
		err = drbd_cfg_context_from_attrs(NULL, info);
		if (err)
			goto fail;

		/* It was present, and valid,
		 * copy it over to the reply skb. */
		err = nla_put_nohdr(adm_ctx->reply_skb,
				info->attrs[DRBD_NLA_CFG_CONTEXT]->nla_len,
				info->attrs[DRBD_NLA_CFG_CONTEXT]);
		if (err)
			goto fail;

		/* and assign stuff to the adm_ctx */
		nla = nested_attr_tb[__nla_type(T_ctx_volume)];
		if (nla)
			adm_ctx->volume = nla_get_u32(nla);
		nla = nested_attr_tb[__nla_type(T_ctx_resource_name)];
		if (nla)
			adm_ctx->resource_name = nla_data(nla);
		adm_ctx->my_addr = nested_attr_tb[__nla_type(T_ctx_my_addr)];
		adm_ctx->peer_addr = nested_attr_tb[__nla_type(T_ctx_peer_addr)];
		if ((adm_ctx->my_addr &&
		     nla_len(adm_ctx->my_addr) > sizeof(adm_ctx->connection->my_addr)) ||
		    (adm_ctx->peer_addr &&
		     nla_len(adm_ctx->peer_addr) > sizeof(adm_ctx->connection->peer_addr))) {
			err = -EINVAL;
			goto fail;
		}
	}

	adm_ctx->minor = d_in->minor;
	adm_ctx->device = minor_to_device(d_in->minor);

	/* We are protected by the global genl_lock().
	 * But we may explicitly drop it/retake it in drbd_adm_set_role(),
	 * so make sure this object stays around. */
	if (adm_ctx->device)
		kref_get(&adm_ctx->device->kref);

	if (adm_ctx->resource_name) {
		adm_ctx->resource = drbd_find_resource(adm_ctx->resource_name);
	}

	if (!adm_ctx->device && (flags & DRBD_ADM_NEED_MINOR)) {
		drbd_msg_put_info(adm_ctx->reply_skb, "unknown minor");
		return ERR_MINOR_INVALID;
	}
	if (!adm_ctx->resource && (flags & DRBD_ADM_NEED_RESOURCE)) {
		drbd_msg_put_info(adm_ctx->reply_skb, "unknown resource");
		if (adm_ctx->resource_name)
			return ERR_RES_NOT_KNOWN;
		return ERR_INVALID_REQUEST;
	}

	if (flags & DRBD_ADM_NEED_CONNECTION) {
		if (adm_ctx->resource) {
			drbd_msg_put_info(adm_ctx->reply_skb, "no resource name expected");
			return ERR_INVALID_REQUEST;
		}
		if (adm_ctx->device) {
			drbd_msg_put_info(adm_ctx->reply_skb, "no minor number expected");
			return ERR_INVALID_REQUEST;
		}
		if (adm_ctx->my_addr && adm_ctx->peer_addr)
			adm_ctx->connection = conn_get_by_addrs(nla_data(adm_ctx->my_addr),
							  nla_len(adm_ctx->my_addr),
							  nla_data(adm_ctx->peer_addr),
							  nla_len(adm_ctx->peer_addr));
		if (!adm_ctx->connection) {
			drbd_msg_put_info(adm_ctx->reply_skb, "unknown connection");
			return ERR_INVALID_REQUEST;
		}
	}

	/* some more paranoia, if the request was over-determined */
	if (adm_ctx->device && adm_ctx->resource &&
	    adm_ctx->device->resource != adm_ctx->resource) {
		pr_warn("request: minor=%u, resource=%s; but that minor belongs to resource %s\n",
			adm_ctx->minor, adm_ctx->resource->name,
			adm_ctx->device->resource->name);
		drbd_msg_put_info(adm_ctx->reply_skb, "minor exists in different resource");
		return ERR_INVALID_REQUEST;
	}
	if (adm_ctx->device &&
	    adm_ctx->volume != VOLUME_UNSPECIFIED &&
	    adm_ctx->volume != adm_ctx->device->vnr) {
		pr_warn("request: minor=%u, volume=%u; but that minor is volume %u in %s\n",
			adm_ctx->minor, adm_ctx->volume,
			adm_ctx->device->vnr, adm_ctx->device->resource->name);
		drbd_msg_put_info(adm_ctx->reply_skb, "minor exists as different volume");
		return ERR_INVALID_REQUEST;
	}

	/* still, provide adm_ctx->resource always, if possible. */
	if (!adm_ctx->resource) {
		adm_ctx->resource = adm_ctx->device ? adm_ctx->device->resource
			: adm_ctx->connection ? adm_ctx->connection->resource : NULL;
		if (adm_ctx->resource)
			kref_get(&adm_ctx->resource->kref);
	}

	return NO_ERROR;

fail:
	nlmsg_free(adm_ctx->reply_skb);
	adm_ctx->reply_skb = NULL;
	return err;
}