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Date:   Sat, 15 Dec 2018 15:01:48 -0800
From:   Roopa Prabhu <roopa@...ulusnetworks.com>
To:     David Ahern <dsa@...ulusnetworks.com>
Cc:     David Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: Re: [PATCH net-next v2 1/4] net: rtnetlink: support for fdb get

On Sat, Dec 15, 2018 at 2:20 PM David Ahern <dsa@...ulusnetworks.com> wrote:
>
> On 12/14/18 9:14 PM, Roopa Prabhu wrote:
> > @@ -4021,6 +4033,171 @@ static int rtnl_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb)
> >       return skb->len;
> >  }
> >
> > +static int valid_fdb_get_strict(const struct nlmsghdr *nlh,
> > +                             struct nlattr **tb, u8 *ndm_flags,
> > +                             int *br_idx, int *brport_idx, u8 **addr,
> > +                             u16 *vid, struct netlink_ext_ack *extack)
> > +{
> > +     struct ndmsg *ndm;
> > +     int err, i;
> > +
> > +     if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ndm))) {
> > +             NL_SET_ERR_MSG(extack, "Invalid header for fdb get request");
> > +             return -EINVAL;
> > +     }
> > +
> > +     ndm = nlmsg_data(nlh);
> > +     if (ndm->ndm_pad1  || ndm->ndm_pad2  || ndm->ndm_state ||
> > +         ndm->ndm_type) {
> > +             NL_SET_ERR_MSG(extack, "Invalid values in header for fdb get request");
> > +             return -EINVAL;
> > +     }
> > +
> > +     if (ndm->ndm_flags & ~(NTF_MASTER | NTF_SELF)) {
> > +             NL_SET_ERR_MSG(extack, "Invalid flags in header for fdb get request");
> > +             return -EINVAL;
> > +     }
> > +
> > +     err = nlmsg_parse_strict(nlh, sizeof(struct ndmsg), tb, NDA_MAX,
> > +                              nda_policy, extack);
> > +     if (err < 0)
> > +             return err;
> > +
> > +     *ndm_flags = ndm->ndm_flags;
> > +     *brport_idx = ndm->ndm_ifindex;
> > +     for (i = 0; i <= NDA_MAX; ++i) {
> > +             if (!tb[i])
> > +                     continue;
> > +
> > +             switch (i) {
> > +             case NDA_MASTER:
> > +                     if (nla_len(tb[i]) != sizeof(u32)) {
>
> This is checked by the policy during the nlsmsg_parse.
>
> > +                             NL_SET_ERR_MSG(extack, "Invalid MASTER attribute in fdb get request");
> > +                             return -EINVAL;
> > +                     }
> > +                     *br_idx = nla_get_u32(tb[i]);
> > +                     break;
> > +             case NDA_LLADDR:
> > +                     if (!tb[i] || nla_len(tb[i]) != ETH_ALEN) {
>
> The nla_len check is needed here, but '!tb[i]' is redundant with the
> check after the for statement.
>
> > +                             NL_SET_ERR_MSG(extack, "Invalid address in fdb get request");
> > +                             return -EINVAL;
> > +                     }
> > +                     *addr = nla_data(tb[i]);
> > +                     break;
> > +             case NDA_VLAN:
> > +                     err = fdb_vid_parse(tb[i], vid, extack);
> > +                     if (err)
> > +                             return err;
> > +                     break;
> > +             case NDA_VNI:
> > +                     if (nla_len(tb[i]) != sizeof(u32)) {
>
> And here the len is already checked by the policy.
>
> > +                             NL_SET_ERR_MSG(extack, "Invalid VNI in fdb get request");
> > +                             return err;
> > +                     }
> > +                     break;

ack  to all the above.  I will remove the check and keep the NDA_VNI
case stmt empty. (ideally vxlan driver should be checking all the
vxlan attributes. tb[] is passed to the vxlan ndo. this is consistent
with all other  fdb operations)

> > +             default:
> > +                     NL_SET_ERR_MSG(extack, "Unsupported attribute in fdb get request");
> > +                     return -EINVAL;
> > +             }
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static int rtnl_fdb_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
> > +                     struct netlink_ext_ack *extack)
> > +{
> > +     struct net_device *dev = NULL, *br_dev = NULL;
> > +     const struct net_device_ops *ops = NULL;
> > +     struct net *net = sock_net(in_skb->sk);
> > +     struct nlattr *tb[NDA_MAX + 1];
> > +     struct sk_buff *skb;
> > +     int brport_idx = 0;
> > +     u8 ndm_flags = 0;
> > +     int br_idx = 0;
> > +     u8 *addr = NULL;
> > +     u16 vid = 0;
> > +     int err;
> > +
> > +     err = valid_fdb_get_strict(nlh, tb, &ndm_flags, &br_idx,
> > +                                &brport_idx, &addr, &vid, extack);
> > +     if (err < 0)
> > +             return err;
> > +
> > +     if (brport_idx) {
> > +             dev = __dev_get_by_index(net, brport_idx);
> > +             if (!dev) {
> > +                     NL_SET_ERR_MSG(extack, "Unknown device ifindex");
> > +                     return -ENODEV;
> > +             }
> > +     }
> > +
> > +     if (br_idx) {
> > +             if (dev) {
> > +                     NL_SET_ERR_MSG(extack, "Master and device are mutually exclusive");
> > +                     return -EINVAL;
> > +             }
> > +
> > +             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;
> > +     }
> > +
> > +     if (dev) {
> > +             if (!ndm_flags || (ndm_flags & NTF_MASTER)) {
> > +                     if (!(dev->priv_flags & IFF_BRIDGE_PORT)) {
> > +                             NL_SET_ERR_MSG(extack, "Device is not a bridge port");
> > +                             return -EINVAL;
> > +                     }
> > +                     br_dev = netdev_master_upper_dev_get(dev);
> > +                     if (!br_dev) {
> > +                             NL_SET_ERR_MSG(extack, "Master of device not found");
> > +                             return -EINVAL;
> > +                     }
> > +                     ops = br_dev->netdev_ops;
> > +             } else {
> > +                     if (!(ndm_flags & NTF_SELF)) {
> > +                             NL_SET_ERR_MSG(extack, "Missing NTF_SELF");
> > +                             return -EINVAL;
> > +                     }
> > +                     ops = dev->netdev_ops;
> > +             }
> > +     }
> > +
> > +     if (!br_dev && !dev) {
> > +             NL_SET_ERR_MSG(extack, "No device specified");
> > +             return -ENODEV;
> > +     }
> > +
> > +     if (!ops || !ops->ndo_fdb_get) {
> > +             NL_SET_ERR_MSG(extack, "Fdb get operation not supported by device");
> > +             return -EOPNOTSUPP;
> > +     }
> > +
> > +     skb = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
> > +     if (!skb)
> > +             return -ENOBUFS;
> > +
> > +     if (br_dev)
> > +             err = ops->ndo_fdb_get(skb, tb, br_dev, addr, vid,
> > +                                    NETLINK_CB(in_skb).portid,
> > +                                    nlh->nlmsg_seq, extack);
> > +     else
> > +             err = ops->ndo_fdb_get(skb, tb, dev, addr, vid,
> > +                                    NETLINK_CB(in_skb).portid,
> > +                                    nlh->nlmsg_seq, extack);
>
> The above can be simplified to one ndo_fdb_get call.
>
>         if (br_dev)
>                 dev = br_dev;
>
>         err = ops->ndo_fdb_get(skb, tb, dev, addr, vid,
>                                NETLINK_CB(in_skb).portid,
>                                nlh->nlmsg_seq, extack);
>
> Or unless I am missing something, br_dev as a separate variable is not
> really needed and it would simplify things just a bit.
>
>

ack. I did have it this way but after a few iterations moved it..don't
remember now.
Will move it to the above



>
> > +     if (err)
> > +             goto out;
> > +
> > +     return rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
> > +out:
> > +     kfree_skb(skb);
> > +     return err;
> > +}
> > +
> >  static int brport_nla_put_flag(struct sk_buff *skb, u32 flags, u32 mask,
> >                              unsigned int attrnum, unsigned int flag)
> >  {
> > @@ -5081,7 +5258,7 @@ void __init rtnetlink_init(void)
> >
> >       rtnl_register(PF_BRIDGE, RTM_NEWNEIGH, rtnl_fdb_add, NULL, 0);
> >       rtnl_register(PF_BRIDGE, RTM_DELNEIGH, rtnl_fdb_del, NULL, 0);
> > -     rtnl_register(PF_BRIDGE, RTM_GETNEIGH, NULL, rtnl_fdb_dump, 0);
> > +     rtnl_register(PF_BRIDGE, RTM_GETNEIGH, rtnl_fdb_get, rtnl_fdb_dump, 0);
> >
> >       rtnl_register(PF_BRIDGE, RTM_GETLINK, NULL, rtnl_bridge_getlink, 0);
> >       rtnl_register(PF_BRIDGE, RTM_DELLINK, rtnl_bridge_dellink, NULL, 0);
> >
>

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