Re: [PATCH net-next 1/4] net: rtnetlink: support for fdb get

[Roopa Prabhu <roopa@cumulusnetworks.com>]

On Fri, Dec 14, 2018 at 9:55 AM David Ahern <dsa@cumulusnetworks.com> wrote:
>
> On 12/14/18 10:43 AM, Roopa Prabhu wrote:
> > diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> > index f8bdb8ad..fcea76b 100644
> > --- a/net/core/rtnetlink.c
> > +++ b/net/core/rtnetlink.c
> > @@ -4021,6 +4021,111 @@ static int rtnl_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb)
> >       return skb->len;
> >  }
> >
> > +static int rtnl_fdb_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
> > +                     struct netlink_ext_ack *extack)
> > +{
> > +     const struct net_device_ops *ops = NULL;
> > +     struct net *net = sock_net(in_skb->sk);
> > +     struct net_device *dev = NULL, *br_dev = NULL;
> > +     struct nlattr *tb[NDA_MAX + 1];
> > +     struct sk_buff *skb;
> > +     struct ndmsg *ndm;
> > +     int br_idx = 0;
> > +     u8 *addr;
> > +     u16 vid;
> > +     int err;
> > +
> > +     err = nlmsg_parse(nlh, sizeof(*ndm), tb, NDA_MAX, NULL, extack);
>
> New stuff should go in with strict checking, so nlmsg_parse_strict and a
> check for any unsupported attributes (NDA) or ndm entries in the request.

makes sense.

>
> Also, please add an nla_policy for easier NDA attributes ...

yes agreed. NDA attrs have not had a policy.
maybe an incremental patch ?, NDA_* attributes are used in bridge
vxlan and neighbour code, need a common place to put the policy.
(suggestions ?)


>
> > +     if (err < 0)
> > +             return err;
> > +
> > +     ndm = nlmsg_data(nlh);
> > +     if (ndm->ndm_ifindex) {
> > +             dev = __dev_get_by_index(net, ndm->ndm_ifindex);
> > +             if (!dev) {
> > +                     NL_SET_ERR_MSG(extack, "unknown dev ifindex");
>
> General comment on all of the extack messages: No abbreviations in the
> message, and it is nice to always start with a capital letter. "Unknown
> device index"

ack,

will send a v2


>
> > +                     return -ENODEV;
> > +             }
> > +     }
> > +
> > +     if (!tb[NDA_LLADDR] || nla_len(tb[NDA_LLADDR]) != ETH_ALEN) {
> > +             NL_SET_ERR_MSG(extack, "invalid address");
> > +             return -EINVAL;
> > +     }
> > +
> > +     addr = nla_data(tb[NDA_LLADDR]);
> > +
> > +     err = fdb_vid_parse(tb[NDA_VLAN], &vid, extack);
> > +     if (err)
> > +             return err;
> > +
> > +     if (tb[NDA_MASTER]) {
> > +             if (dev) {
> > +                     NL_SET_ERR_MSG(extack, "master and dev are mutually exclusive");
> > +                     return -EINVAL;
> > +             }
> > +
> > +             br_idx = nla_get_u32(tb[NDA_MASTER]);
>
> ... so you know that NDA_MASTER is a u32.
>
> > +             br_dev = __dev_get_by_index(net, br_idx);
> > +             if (!br_dev) {
> > +                     NL_SET_ERR_MSG(extack, "invalid master ifindex");
> > +                     return -EINVAL;
> > +             }
> > +             ops = br_dev->netdev_ops;
> > +     }
> > +
>