Re: [RFC net-next v4 4/9] bridge: mrp: Implement netlink interface to configure MRP

[Nikolay Aleksandrov <nikolay@cumulusnetworks.com>]

On 27/03/2020 11:21, Horatiu Vultur wrote:
> Implement netlink interface to configure MRP. The implementation
> will do sanity checks over the attributes and then eventually call the MRP
> interface.
> 
> Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
> ---
>  net/bridge/br_mrp_netlink.c | 176 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 176 insertions(+)
>  create mode 100644 net/bridge/br_mrp_netlink.c
> 

Hi Horatiu,

> diff --git a/net/bridge/br_mrp_netlink.c b/net/bridge/br_mrp_netlink.c
> new file mode 100644
> index 000000000000..043b7f6cddbe
> --- /dev/null
> +++ b/net/bridge/br_mrp_netlink.c
> @@ -0,0 +1,176 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +
> +#include <net/genetlink.h>
> +
> +#include <uapi/linux/mrp_bridge.h>
> +#include "br_private.h"
> +#include "br_private_mrp.h"
> +
> +static int br_mrp_parse_instance(struct net_bridge *br, struct nlattr *attr,
> +				 int cmd)
> +{
> +	struct br_mrp_instance *instance;
> +
> +	if (nla_len(attr) != sizeof(*instance))
> +		return -EINVAL;
> +
> +	instance = nla_data(attr);
> +
> +	if (cmd == RTM_SETLINK)
> +		return br_mrp_add(br, instance);
> +	else
> +		return br_mrp_del(br, instance);
> +}
> +
> +static int br_mrp_parse_port_state(struct net_bridge *br,
> +				   struct net_bridge_port *p,
> +				   struct nlattr *attr)
> +{
> +	enum br_mrp_port_state_type state;
> +
> +	if (nla_len(attr) != sizeof(u32) || !p)
> +		return -EINVAL;
> +
> +	state = nla_get_u32(attr);
> +
> +	return br_mrp_set_port_state(p, state);
> +}
> +
> +static int br_mrp_parse_port_role(struct net_bridge *br,
> +				  struct net_bridge_port *p,
> +				  struct nlattr *attr)
> +{
> +	struct br_mrp_port_role *role;
> +
> +	if (nla_len(attr) != sizeof(*role) || !p)
> +		return -EINVAL;
> +
> +	role = nla_data(attr);
> +
> +	return br_mrp_set_port_role(p, role->ring_id, role->role);
> +}
> +
> +static int br_mrp_parse_ring_state(struct net_bridge *br, struct nlattr *attr)
> +{
> +	struct br_mrp_ring_state *state;
> +
> +	if (nla_len(attr) != sizeof(*state))
> +		return -EINVAL;
> +
> +	state = nla_data(attr);
> +
> +	return br_mrp_set_ring_state(br, state->ring_id, state->ring_state);
> +}
> +
> +static int br_mrp_parse_ring_role(struct net_bridge *br, struct nlattr *attr)
> +{
> +	struct br_mrp_ring_role *role;
> +
> +	if (nla_len(attr) != sizeof(*role))
> +		return -EINVAL;
> +
> +	role = nla_data(attr);
> +
> +	return br_mrp_set_ring_role(br, role->ring_id, role->ring_role);
> +}
> +
> +static int br_mrp_parse_start_test(struct net_bridge *br, struct nlattr *attr)
> +{
> +	struct br_mrp_start_test *test;
> +
> +	if (nla_len(attr) != sizeof(*test))
> +		return -EINVAL;
> +
> +	test = nla_data(attr);
> +
> +	return br_mrp_start_test(br, test->ring_id, test->interval,
> +				 test->max_miss, test->period);
> +}
> +
> +int br_mrp_parse(struct net_bridge *br, struct net_bridge_port *p,
> +		 struct nlattr *attr, int cmd)
> +{
> +	struct nlattr *mrp;
> +	int rem, err;
> +
> +	nla_for_each_nested(mrp, attr, rem) {
> +		err = 0;
> +		switch (nla_type(mrp)) {
> +		case IFLA_BRIDGE_MRP_INSTANCE:
> +			err = br_mrp_parse_instance(br, mrp, cmd);
> +			if (err)
> +				return err;
> +			break;
> +		case IFLA_BRIDGE_MRP_PORT_STATE:
> +			err = br_mrp_parse_port_state(br, p, mrp);
> +			if (err)
> +				return err;
> +			break;
> +		case IFLA_BRIDGE_MRP_PORT_ROLE:
> +			err = br_mrp_parse_port_role(br, p, mrp);
> +			if (err)
> +				return err;
> +			break;
> +		case IFLA_BRIDGE_MRP_RING_STATE:
> +			err = br_mrp_parse_ring_state(br, mrp);
> +			if (err)
> +				return err;
> +			break;
> +		case IFLA_BRIDGE_MRP_RING_ROLE:
> +			err = br_mrp_parse_ring_role(br, mrp);
> +			if (err)
> +				return err;
> +			break;
> +		case IFLA_BRIDGE_MRP_START_TEST:
> +			err = br_mrp_parse_start_test(br, mrp);
> +			if (err)
> +				return err;
> +			break;
> +		}
> +	}
> +
> +	return 0;
> +}

All of the above can be implemented via nla_parse_nested() with a proper policy.
You don't have to manually check for the attribute size. Then your code follows
the netlink normal (e.g. check the bridge netlink handling) of:
 nla_parse_nested(tb)
 if (tb[attr])
    do_something_with(tb[attr])
 ...


> +
> +void br_mrp_port_open(struct net_device *dev, u8 loc)
> +{
> +	struct nlattr *af, *mrp;
> +	struct ifinfomsg *hdr;
> +	struct nlmsghdr *nlh;
> +	struct sk_buff *skb;
> +	int err = -ENOBUFS;
> +	struct net *net;
> +
> +	net = dev_net(dev);
> +
> +	skb = nlmsg_new(1024, GFP_ATOMIC);

Please add a function which calculates the size based on the attribute sizes.

> +	if (!skb)
> +		goto errout;
> +
> +	nlh = nlmsg_put(skb, 0, 0, RTM_NEWLINK, sizeof(*hdr), 0);
> +	if (!nlh)
> +		goto errout;
> +
> +	hdr = nlmsg_data(nlh);
> +	hdr->ifi_family = AF_BRIDGE;
> +	hdr->__ifi_pad = 0;
> +	hdr->ifi_type = dev->type;
> +	hdr->ifi_index = dev->ifindex;
> +	hdr->ifi_flags = dev_get_flags(dev);
> +	hdr->ifi_change = 0;
> +
> +	af = nla_nest_start_noflag(skb, IFLA_AF_SPEC);
> +	mrp = nla_nest_start_noflag(skb, IFLA_BRIDGE_MRP);
> +

These can return an error which has to be handled.

> +	nla_put_u32(skb, IFLA_BRIDGE_MRP_RING_OPEN, loc);
> +

Same for this.

> +	nla_nest_end(skb, mrp);
> +	nla_nest_end(skb, af);
> +	nlmsg_end(skb, nlh);
> +
> +	rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL, GFP_ATOMIC);
> +	return;
> +errout:
> +	rtnl_set_sk_err(net, RTNLGRP_LINK, err);
> +}
> +EXPORT_SYMBOL(br_mrp_port_open);
>