Re: [PATCH net-next 8/9] openvswitch: Allow matching on conntrack label

Joe Stringer
2015-07-31T23:07:04Z

On 31 July 2015 at 06:20, Florian Westphal <fw@strlen.de> wrote:
> Joe Stringer <joestringer@nicira.com> wrote:
>> +/* Load connlabel and ensure it supports 128-bit labels */
>> +static struct xt_match *load_connlabel(struct net *net)
>> +{
>> +#ifdef CONFIG_NF_CONNTRACK_LABELS
>> + struct xt_match *match;
>> + struct xt_mtchk_param mtpar;
>> + struct xt_connlabel_mtinfo info;
>> + int err = -EINVAL;
>> +
>> + match = xt_request_find_match(NFPROTO_UNSPEC, "connlabel", 0);
>> + if (IS_ERR(match)) {
>> + match = NULL;
>> + goto exit;
>> + }
>> +
>> + info.bit = sizeof(struct ovs_key_ct_label) * 8 - 1;
>> + info.options = 0;
>> +
>> + mtpar.net = net;
>> + mtpar.table = match->table;
>> + mtpar.entryinfo = NULL;
>> + mtpar.match = match;
>> + mtpar.matchinfo = &info;
>> + mtpar.hook_mask = BIT(NF_INET_PRE_ROUTING);
>> + mtpar.family = NFPROTO_IPV4;
>> +
>> + err = xt_check_match(&mtpar, XT_ALIGN(match->matchsize), match->proto,
>> + 0);
>
> Yummy :-)

You're very graceful :-)

> Rather than adding a dependency on xtables I think a better option would
> be to move the
>
> par->net->ct.labels_used++;
> words = BITS_TO_LONGS(info->bit+1);
> if (words > par->net->ct.label_words)
> par->net->ct.label_words = words;
>
> parts from the checkentry/destroy hooks of xt_connlabel into
> nf_conntrack_labels.c so that you don't need this mtpar stunt above
> anymore (and I'd like to add ctlabel set support for nft at one point
> so I'd also need to move that out of xt_label).
>
> You can move that out of this series and submit that to nf-devel as
> separate patch if you want.

Thanks for the suggestion, I'll send a patch and adjust this code in
v2 accordingly.

>> + ovs_ct_verify(OVS_KEY_ATTR_CT_LABEL)) {
>> + const struct ovs_key_ct_label *cl;
>> +
>> + cl = nla_data(a[OVS_KEY_ATTR_CT_LABEL]);
>> + SW_FLOW_KEY_MEMCPY(match, ct.label, cl->ct_label,
>> + sizeof(*cl), is_mask);
>> + *attrs &= ~(1ULL << OVS_KEY_ATTR_CT_LABEL);
>> + }
>
> So you're using labels as arbitrary 128 bit identifier, right?
>
> Nothing wrong with that, just asking.

Right, it's exposed as an arbitrarily maskable/settable field of 128
bits in length, as that's the maximum today. So it's effectively up to
userspace to use it as a bunch of 1-bit flags or N-bit fields within
the range of the 128 bits.