Re: [PATCH net-next v4 4/5] ipv6: ioam: Support for IOAM injection with lwtunnels

[Justin Iurman <justin.iurman@uliege.be>]

> On Thu, 27 May 2021 17:16:51 +0200 Justin Iurman wrote:
>> Add support for the IOAM inline insertion (only for the host-to-host use case)
>> which is per-route configured with lightweight tunnels. The target is iproute2
>> and the patch is ready. It will be posted as soon as this patchset is merged.
>> Here is an overview:
>> 
>> $ ip -6 ro ad fc00::1/128 encap ioam6 trace type 0x800000 ns 1 size 12 dev eth0
>> 
>> This example configures an IOAM Pre-allocated Trace option attached to the
>> fc00::1/128 prefix. The IOAM namespace (ns) is 1, the size of the pre-allocated
>> trace data block is 12 octets (size) and only the first IOAM data (bit 0:
>> hop_limit + node id) is included in the trace (type) represented as a bitfield.
>> 
>> The reason why the in-transit (IPv6-in-IPv6 encapsulation) use case is not
>> implemented is explained on the patchset cover.
>> 
>> Signed-off-by: Justin Iurman <justin.iurman@uliege.be>
> 
>> +static const struct nla_policy ioam6_iptunnel_policy[IOAM6_IPTUNNEL_MAX + 1] =
>> {
>> +	[IOAM6_IPTUNNEL_TRACE]	= { .type = NLA_BINARY },
> 
> Please use NLA_POLICY_EXACT_LEN(sizeof(..)), that should avoid the need
> for explicit check in the code.

ACK.

>
>> +};
> 
>> +static int ioam6_build_state(struct net *net, struct nlattr *nla,
>> +			     unsigned int family, const void *cfg,
>> +			     struct lwtunnel_state **ts,
>> +			     struct netlink_ext_ack *extack)
>> +{
>> +	struct nlattr *tb[IOAM6_IPTUNNEL_MAX + 1];
>> +	struct ioam6_lwt_encap *tuninfo;
>> +	struct ioam6_trace_hdr *trace;
>> +	struct lwtunnel_state *s;
>> +	int len_aligned;
>> +	int len, err;
>> +
>> +	if (family != AF_INET6)
>> +		return -EINVAL;
>> +
>> +	err = nla_parse_nested(tb, IOAM6_IPTUNNEL_MAX, nla,
>> +			       ioam6_iptunnel_policy, extack);
>> +	if (err < 0)
>> +		return err;
>> +
>> +	if (!tb[IOAM6_IPTUNNEL_TRACE])
>> +		return -EINVAL;
>> +
>> +	trace = nla_data(tb[IOAM6_IPTUNNEL_TRACE]);
>> +	if (nla_len(tb[IOAM6_IPTUNNEL_TRACE]) != sizeof(*trace))
>> +		return -EINVAL;
>> +
>> +	if (!ioam6_validate_trace_hdr(trace))
>> +		return -EINVAL;
> 
> It'd be good to set the extack message and attribute here. And perhaps
> a message for the case of trace missing.

ACK.