On Fri, Aug 26, 2022 at 11:05 AM Nicolas Dichtel
<nicolas.dichtel@xxxxxxxxx> wrote:
>
>
> Le 25/08/2022 à 17:46, Eyal Birger a écrit :
> > Allow specifying the xfrm interface if_id and link as part of a route
> > metadata using the lwtunnel infrastructure.
> >
> > This allows for example using a single xfrm interface in collect_md
> > mode as the target of multiple routes each specifying a different if_id.
> >
> > With the appropriate changes to iproute2, considering an xfrm device
> > ipsec1 in collect_md mode one can for example add a route specifying
> > an if_id like so:
> >
> > ip route add <SUBNET> dev ipsec1 encap xfrm if_id 1
> >
> > In which case traffic routed to the device via this route would use
> > if_id in the xfrm interface policy lookup.
> >
> > Or in the context of vrf, one can also specify the "link" property:
> >
> > ip route add <SUBNET> dev ipsec1 encap xfrm if_id 1 link_dev eth15
> >
> > Signed-off-by: Eyal Birger <eyal.birger@xxxxxxxxx>
> >
> > ----
> >
> > v3: netlink improvements as suggested by Nikolay Aleksandrov and
> > Nicolas Dichtel
> >
> > v2:
> > - move lwt_xfrm_info() helper to dst_metadata.h
> > - add "link" property as suggested by Nicolas Dichtel
> > ---
> > include/net/dst_metadata.h | 11 +++++
> > include/uapi/linux/lwtunnel.h | 10 +++++
> > net/core/lwtunnel.c | 1 +
> > net/xfrm/xfrm_interface.c | 85 +++++++++++++++++++++++++++++++++++
> > 4 files changed, 107 insertions(+)
> >
> > diff --git a/include/net/dst_metadata.h b/include/net/dst_metadata.h
> > index e4b059908cc7..57f75960fa28 100644
> > --- a/include/net/dst_metadata.h
> > +++ b/include/net/dst_metadata.h
> > @@ -60,13 +60,24 @@ skb_tunnel_info(const struct sk_buff *skb)
> > return NULL;
> > }
> >
> > +static inline struct xfrm_md_info *lwt_xfrm_info(struct lwtunnel_state *lwt)
> > +{
> > + return (struct xfrm_md_info *)lwt->data;
> > +}
> > +
> > static inline struct xfrm_md_info *skb_xfrm_md_info(const struct sk_buff *skb)
> > {
> > struct metadata_dst *md_dst = skb_metadata_dst(skb);
> > + struct dst_entry *dst;
> >
> > if (md_dst && md_dst->type == METADATA_XFRM)
> > return &md_dst->u.xfrm_info;
> >
> > + dst = skb_dst(skb);
> > + if (dst && dst->lwtstate &&
> > + dst->lwtstate->type == LWTUNNEL_ENCAP_XFRM)
> > + return lwt_xfrm_info(dst->lwtstate);
> > +
> > return NULL;
> > }
> >
> > diff --git a/include/uapi/linux/lwtunnel.h b/include/uapi/linux/lwtunnel.h
> > index 2e206919125c..229655ef792f 100644
> > --- a/include/uapi/linux/lwtunnel.h
> > +++ b/include/uapi/linux/lwtunnel.h
> > @@ -15,6 +15,7 @@ enum lwtunnel_encap_types {
> > LWTUNNEL_ENCAP_SEG6_LOCAL,
> > LWTUNNEL_ENCAP_RPL,
> > LWTUNNEL_ENCAP_IOAM6,
> > + LWTUNNEL_ENCAP_XFRM,
> > __LWTUNNEL_ENCAP_MAX,
> > };
> >
> > @@ -111,4 +112,13 @@ enum {
> >
> > #define LWT_BPF_MAX_HEADROOM 256
> >
> > +enum {
> > + LWT_XFRM_UNSPEC,
> > + LWT_XFRM_IF_ID,
> > + LWT_XFRM_LINK,
> > + __LWT_XFRM_MAX,
> > +};
> > +
> > +#define LWT_XFRM_MAX (__LWT_XFRM_MAX - 1)
> > +
> > #endif /* _UAPI_LWTUNNEL_H_ */
> > diff --git a/net/core/lwtunnel.c b/net/core/lwtunnel.c
> > index 9ccd64e8a666..6fac2f0ef074 100644
> > --- a/net/core/lwtunnel.c
> > +++ b/net/core/lwtunnel.c
> > @@ -50,6 +50,7 @@ static const char *lwtunnel_encap_str(enum lwtunnel_encap_types encap_type)
> > return "IOAM6";
> > case LWTUNNEL_ENCAP_IP6:
> > case LWTUNNEL_ENCAP_IP:
> > + case LWTUNNEL_ENCAP_XFRM:
> > case LWTUNNEL_ENCAP_NONE:
> > case __LWTUNNEL_ENCAP_MAX:
> > /* should not have got here */
> > diff --git a/net/xfrm/xfrm_interface.c b/net/xfrm/xfrm_interface.c
> > index e9a355047468..495dee8b0764 100644
> > --- a/net/xfrm/xfrm_interface.c
> > +++ b/net/xfrm/xfrm_interface.c
> > @@ -60,6 +60,88 @@ struct xfrmi_net {
> > struct xfrm_if __rcu *collect_md_xfrmi;
> > };
> >
> > +static const struct nla_policy xfrm_lwt_policy[LWT_XFRM_MAX + 1] = {
> > + [LWT_XFRM_IF_ID] = NLA_POLICY_MIN(NLA_U32, 1),
> > + [LWT_XFRM_LINK] = NLA_POLICY_MIN(NLA_S32, 1),
> IMHO, it would be better to keep consistency with IFLA_XFRM_LINK.
>
> $ git grep _LINK.*NLA_U32 net/ drivers/net/
> drivers/net/gtp.c: [GTPA_LINK] = { .type = NLA_U32, },
> drivers/net/vxlan/vxlan_core.c: [IFLA_VXLAN_LINK] = { .type = NLA_U32 },
> ...
> net/core/rtnetlink.c: [IFLA_LINK] = { .type = NLA_U32 },
> ...
> net/ipv4/ip_gre.c: [IFLA_GRE_LINK] = { .type = NLA_U32 },
> net/ipv4/ip_vti.c: [IFLA_VTI_LINK] = { .type = NLA_U32 },
> net/ipv4/ipip.c: [IFLA_IPTUN_LINK] = { .type = NLA_U32 },
> net/ipv6/ip6_gre.c: [IFLA_GRE_LINK] = { .type = NLA_U32 },
> net/ipv6/ip6_tunnel.c: [IFLA_IPTUN_LINK] = { .type = NLA_U32 },
> net/ipv6/ip6_vti.c: [IFLA_VTI_LINK] = { .type = NLA_U32 },
> net/ipv6/sit.c: [IFLA_IPTUN_LINK] = { .type = NLA_U32 },
> net/sched/cls_u32.c: [TCA_U32_LINK] = { .type = NLA_U32 },
> ...
> net/xfrm/xfrm_interface.c: [IFLA_XFRM_LINK] = { .type = NLA_U32 },
> $ git grep _LINK.*NLA_S32 net/ drivers/net/
> net/core/rtnetlink.c: [IFLA_LINK_NETNSID] = { .type = NLA_S32 },
> $
>
> They all are U32. Adding one S32 would just add confusion.
Thanks for this input!
Indeed going over the other references it seems ifindex is treated as U32
when interfacing with userspace almost everywhere including netlink and
bpf. In the IOCTL interface it seems to be implemented as int, but at
least on my Ubuntu machine the manpage for e.g. if_nametoindex() describes
it as returning unsigned int.
Therefore I intend to resubmit this as U32.
Thanks,
Eyal.
