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Date: Fri, 26 Aug 2022 13:50:45 +0300
From: Nikolay Aleksandrov <razor@...ckwall.org>
To: Eyal Birger <eyal.birger@...il.com>, nicolas.dichtel@...nd.com
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
pabeni@...hat.com, steffen.klassert@...unet.com,
herbert@...dor.apana.org.au, dsahern@...nel.org,
contact@...elbtn.com, pablo@...filter.org, daniel@...earbox.net,
netdev@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH ipsec-next,v3 3/3] xfrm: lwtunnel: add lwtunnel support
for xfrm interfaces in collect_md mode
On 26/08/2022 13:18, Eyal Birger wrote:
> On Fri, Aug 26, 2022 at 11:05 AM Nicolas Dichtel
> <nicolas.dichtel@...nd.com> 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@...il.com>
>>>
>>> ----
>>>
>>> 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.
Ack, good point, note that ifindex is not always a u32 and ifindex itself is usually a
signed integer field in structs (e.g. net_device), as well as flowic_oif (flowi_oif). :)
rtnetlink.c: [IFLA_NEW_IFINDEX] = NLA_POLICY_MIN(NLA_S32, 1),
rtnetlink.c: [NDA_IFINDEX] = NLA_POLICY_MIN(NLA_S32, 1),
Just using the old U32 code and making link a u32 should be ok.
Cheers,
Nik
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