netdev - Re: [PATCH v10 04/12] rtnl: add option for setting link xdp prog

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Message-ID: <20160720173521.GB16467@gmail.com>
Date:	Wed, 20 Jul 2016 10:35:22 -0700
From:	Brenden Blanco <bblanco@...mgrid.com>
To:	Daniel Borkmann <daniel@...earbox.net>
Cc:	davem@...emloft.net, netdev@...r.kernel.org,
	Jamal Hadi Salim <jhs@...atatu.com>,
	Saeed Mahameed <saeedm@....mellanox.co.il>,
	Martin KaFai Lau <kafai@...com>,
	Jesper Dangaard Brouer <brouer@...hat.com>,
	Ari Saha <as754m@....com>,
	Alexei Starovoitov <alexei.starovoitov@...il.com>,
	Or Gerlitz <gerlitz.or@...il.com>, john.fastabend@...il.com,
	hannes@...essinduktion.org, Thomas Graf <tgraf@...g.ch>,
	Tom Herbert <tom@...bertland.com>,
	Tariq Toukan <ttoukan.linux@...il.com>
Subject: Re: [PATCH v10 04/12] rtnl: add option for setting link xdp prog

On Wed, Jul 20, 2016 at 10:38:49AM +0200, Daniel Borkmann wrote:
> On 07/19/2016 09:16 PM, Brenden Blanco wrote:
> >Sets the bpf program represented by fd as an early filter in the rx path
> >of the netdev. The fd must have been created as BPF_PROG_TYPE_XDP.
> >Providing a negative value as fd clears the program. Getting the fd back
> >via rtnl is not possible, therefore reading of this value merely
> >provides a bool whether the program is valid on the link or not.
> >
> >Signed-off-by: Brenden Blanco <bblanco@...mgrid.com>
> [...]
> >@@ -2054,6 +2101,23 @@ static int do_setlink(const struct sk_buff *skb,
> >  		status |= DO_SETLINK_NOTIFY;
> >  	}
> >
> >+	if (tb[IFLA_XDP]) {
> >+		struct nlattr *xdp[IFLA_XDP_MAX + 1];
> >+
> >+		err = nla_parse_nested(xdp, IFLA_XDP_MAX, tb[IFLA_XDP],
> >+				       ifla_xdp_policy);
> >+		if (err < 0)
> >+			goto errout;
> >+
> >+		if (xdp[IFLA_XDP_FD]) {
> >+			err = dev_change_xdp_fd(dev,
> >+						nla_get_s32(xdp[IFLA_XDP_FD]));
> >+			if (err)
> >+				goto errout;
> >+			status |= DO_SETLINK_NOTIFY;
> >+		}
> 
> For the setlink case IFLA_XDP_ATTACHED has no meaning currently, so I'd
> suggest it would be good to be strict and still add a:
> 
> 		/* Only used in rtnl_fill_ifinfo currently. */
> 		if (xdp[IFLA_XDP_ATTACHED]) {
> 			err = -EINVAL;
> 			goto errout;
> 		}
> 
Agreed.
> >+	}
> >+
> >  errout:
> >  	if (status & DO_SETLINK_MODIFIED) {
> >  		if (status & DO_SETLINK_NOTIFY)
> >
>