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Date: Tue, 15 Mar 2022 22:09:25 -0700
From: Roopa Prabhu <roopa@...dia.com>
To: Eyal Birger <eyal.birger@...il.com>
Cc: davem@...emloft.net, kuba@...nel.org, shmulik.ladkani@...il.com,
netdev@...r.kernel.org
Subject: Re: [PATCH net-next] net: geneve: support IPv4/IPv6 as inner protocol
On 3/15/22 20:50, Eyal Birger wrote:
> On Wed, Mar 16, 2022 at 2:33 AM Roopa Prabhu <roopa@...dia.com> wrote:
>>
>> On 3/15/22 13:22, Eyal Birger wrote:
>>> Hi Roopa,
>>>
>>> On Tue, Mar 15, 2022 at 9:57 PM Roopa Prabhu <roopa@...dia.com> wrote:
>>>> On 3/15/22 11:56, Eyal Birger wrote:
>>>>> This patch adds support for encapsulating IPv4/IPv6 within GENEVE.
>>>>>
>>>>> In order use this, a new IFLA_GENEVE_TUN flag needs to be provided at
>>>>> device creation. This property cannot be changed for the time being.
>>>>>
>>>>> In case IP traffic is received on a non-tun device the drop count is
>>>>> increased.
>>>>>
>>>>> Signed-off-by: Eyal Birger <eyal.birger@...il.com>
>>>>> ---
>>>>> drivers/net/geneve.c | 79 +++++++++++++++++++++++++++---------
>>>>> include/uapi/linux/if_link.h | 1 +
>>>>> 2 files changed, 61 insertions(+), 19 deletions(-)
>>>>>
>>>>> diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
>>>>> index a895ff756093..37305ec26250 100644
>>>>> --- a/drivers/net/geneve.c
>>>>> +++ b/drivers/net/geneve.c
>>>>> @@ -56,6 +56,7 @@ struct geneve_config {
>>>>> bool use_udp6_rx_checksums;
>>>>> bool ttl_inherit;
>>>>> enum ifla_geneve_df df;
>>>>> + bool tun;
>>>>> };
>>>>>
>>>>> /* Pseudo network device */
>>>>> @@ -251,17 +252,24 @@ static void geneve_rx(struct geneve_dev *geneve, struct geneve_sock *gs,
>>>>> }
>>>>> }
>>>>>
>>>>> - skb_reset_mac_header(skb);
>>>>> - skb->protocol = eth_type_trans(skb, geneve->dev);
>>>>> - skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);
>>>>> -
>>>>> if (tun_dst)
>>>>> skb_dst_set(skb, &tun_dst->dst);
>>>>>
>>>>> - /* Ignore packet loops (and multicast echo) */
>>>>> - if (ether_addr_equal(eth_hdr(skb)->h_source, geneve->dev->dev_addr)) {
>>>>> - geneve->dev->stats.rx_errors++;
>>>>> - goto drop;
>>>>> + if (gnvh->proto_type == htons(ETH_P_TEB)) {
>>>>> + skb_reset_mac_header(skb);
>>>>> + skb->protocol = eth_type_trans(skb, geneve->dev);
>>>>> + skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);
>>>>> +
>>>>> + /* Ignore packet loops (and multicast echo) */
>>>>> + if (ether_addr_equal(eth_hdr(skb)->h_source,
>>>>> + geneve->dev->dev_addr)) {
>>>>> + geneve->dev->stats.rx_errors++;
>>>>> + goto drop;
>>>>> + }
>>>>> + } else {
>>>>> + skb_reset_mac_header(skb);
>>>>> + skb->dev = geneve->dev;
>>>>> + skb->pkt_type = PACKET_HOST;
>>>>> }
>>>>>
>>>>> oiph = skb_network_header(skb);
>>>>> @@ -345,6 +353,7 @@ static int geneve_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
>>>>> struct genevehdr *geneveh;
>>>>> struct geneve_dev *geneve;
>>>>> struct geneve_sock *gs;
>>>>> + __be16 inner_proto;
>>>>> int opts_len;
>>>>>
>>>>> /* Need UDP and Geneve header to be present */
>>>>> @@ -356,8 +365,13 @@ static int geneve_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
>>>>> if (unlikely(geneveh->ver != GENEVE_VER))
>>>>> goto drop;
>>>>>
>>>>> - if (unlikely(geneveh->proto_type != htons(ETH_P_TEB)))
>>>>> + inner_proto = geneveh->proto_type;
>>>>> +
>>>>> + if (unlikely((inner_proto != htons(ETH_P_TEB) &&
>>>>> + inner_proto != htons(ETH_P_IP) &&
>>>>> + inner_proto != htons(ETH_P_IPV6)))) {
>>>>> goto drop;
>>>>> + }
>>>>>
>>>> unnecessary braces
>>> Will fix.
>>>
>>>>> gs = rcu_dereference_sk_user_data(sk);
>>>>> if (!gs)
>>>>> @@ -367,9 +381,13 @@ static int geneve_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
>>>>> if (!geneve)
>>>>> goto drop;
>>>>>
>>>>> + if (unlikely((!geneve->cfg.tun && inner_proto != htons(ETH_P_TEB)))) {
>>>>> + geneve->dev->stats.rx_dropped++;
>>>>> + goto drop;
>>>>> + }
>>>> Does this change current default behavior ?.
>>>>
>>>> its unclear to be what the current behavior is for a non ETH_P_TEB packet
>>> Currently non ETH_P_TEB packets are silently dropped.
>>> I figured that if the driver supported other ethertypes it would make
>>> sense to increase the count in such case, to assist in debugging wrong
>>> configurations.
>>>
>>> I can remove this if it's better to keep the current behavior.
>> yes, agree. counting is better.
>>
>>
>>>>> +
>>>>> opts_len = geneveh->opt_len * 4;
>>>>> - if (iptunnel_pull_header(skb, GENEVE_BASE_HLEN + opts_len,
>>>>> - htons(ETH_P_TEB),
>>>>> + if (iptunnel_pull_header(skb, GENEVE_BASE_HLEN + opts_len, inner_proto,
>>>>> !net_eq(geneve->net, dev_net(geneve->dev)))) {
>>>>> geneve->dev->stats.rx_dropped++;
>>>>> goto drop;
>>>>> @@ -717,7 +735,8 @@ static int geneve_stop(struct net_device *dev)
>>>>> }
>>>>>
>>>>> static void geneve_build_header(struct genevehdr *geneveh,
>>>>> - const struct ip_tunnel_info *info)
>>>>> + const struct ip_tunnel_info *info,
>>>>> + __be16 inner_proto)
>>>>> {
>>>>> geneveh->ver = GENEVE_VER;
>>>>> geneveh->opt_len = info->options_len / 4;
>>>>> @@ -725,7 +744,7 @@ static void geneve_build_header(struct genevehdr *geneveh,
>>>>> geneveh->critical = !!(info->key.tun_flags & TUNNEL_CRIT_OPT);
>>>>> geneveh->rsvd1 = 0;
>>>>> tunnel_id_to_vni(info->key.tun_id, geneveh->vni);
>>>>> - geneveh->proto_type = htons(ETH_P_TEB);
>>>>> + geneveh->proto_type = inner_proto;
>>>>> geneveh->rsvd2 = 0;
>>>>>
>>>>> if (info->key.tun_flags & TUNNEL_GENEVE_OPT)
>>>>> @@ -734,8 +753,9 @@ static void geneve_build_header(struct genevehdr *geneveh,
>>>>>
>>>>> static int geneve_build_skb(struct dst_entry *dst, struct sk_buff *skb,
>>>>> const struct ip_tunnel_info *info,
>>>>> - bool xnet, int ip_hdr_len)
>>>>> + bool xnet, int ip_hdr_len, bool tun)
>>>>> {
>>>>> + __be16 inner_proto = tun ? skb->protocol : htons(ETH_P_TEB);
>>>>> bool udp_sum = !!(info->key.tun_flags & TUNNEL_CSUM);
>>>>> struct genevehdr *gnvh;
>>>>> int min_headroom;
>>>>> @@ -755,8 +775,8 @@ static int geneve_build_skb(struct dst_entry *dst, struct sk_buff *skb,
>>>>> goto free_dst;
>>>>>
>>>>> gnvh = __skb_push(skb, sizeof(*gnvh) + info->options_len);
>>>>> - geneve_build_header(gnvh, info);
>>>>> - skb_set_inner_protocol(skb, htons(ETH_P_TEB));
>>>>> + geneve_build_header(gnvh, info, inner_proto);
>>>>> + skb_set_inner_protocol(skb, inner_proto);
>>>>> return 0;
>>>>>
>>>>> free_dst:
>>>>> @@ -959,7 +979,8 @@ static int geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
>>>>> }
>>>>> }
>>>>>
>>>>> - err = geneve_build_skb(&rt->dst, skb, info, xnet, sizeof(struct iphdr));
>>>>> + err = geneve_build_skb(&rt->dst, skb, info, xnet, sizeof(struct iphdr),
>>>>> + geneve->cfg.tun);
>>>>> if (unlikely(err))
>>>>> return err;
>>>>>
>>>>> @@ -1038,7 +1059,8 @@ static int geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
>>>>> ttl = key->ttl;
>>>>> ttl = ttl ? : ip6_dst_hoplimit(dst);
>>>>> }
>>>>> - err = geneve_build_skb(dst, skb, info, xnet, sizeof(struct ipv6hdr));
>>>>> + err = geneve_build_skb(dst, skb, info, xnet, sizeof(struct ipv6hdr),
>>>>> + geneve->cfg.tun);
>>>>> if (unlikely(err))
>>>>> return err;
>>>>>
>>>>> @@ -1388,6 +1410,14 @@ static int geneve_configure(struct net *net, struct net_device *dev,
>>>>> dst_cache_reset(&geneve->cfg.info.dst_cache);
>>>>> memcpy(&geneve->cfg, cfg, sizeof(*cfg));
>>>>>
>>>>> + if (geneve->cfg.tun) {
>>>>> + dev->header_ops = NULL;
>>>>> + dev->type = ARPHRD_NONE;
>>>>> + dev->hard_header_len = 0;
>>>>> + dev->addr_len = 0;
>>>>> + dev->flags = IFF_NOARP;
>>>>> + }
>>>>> +
>>>>> err = register_netdevice(dev);
>>>>> if (err)
>>>>> return err;
>>>>> @@ -1561,10 +1591,18 @@ static int geneve_nl2info(struct nlattr *tb[], struct nlattr *data[],
>>>>> #endif
>>>>> }
>>>>>
>>>>> + if (data[IFLA_GENEVE_TUN]) {
>>>>> + if (changelink) {
>>>>> + attrtype = IFLA_GENEVE_TUN;
>>>>> + goto change_notsup;
>>>>> + }
>>>>> + cfg->tun = true;
>>>>> + }
>>>>> +
>>>>> return 0;
>>>>> change_notsup:
>>>>> NL_SET_ERR_MSG_ATTR(extack, data[attrtype],
>>>>> - "Changing VNI, Port, endpoint IP address family, external, and UDP checksum attributes are not supported");
>>>>> + "Changing VNI, Port, endpoint IP address family, external, tun, and UDP checksum attributes are not supported");
>>>>> return -EOPNOTSUPP;
>>>>> }
>>>>>
>>>>> @@ -1799,6 +1837,9 @@ static int geneve_fill_info(struct sk_buff *skb, const struct net_device *dev)
>>>>> if (nla_put_u8(skb, IFLA_GENEVE_TTL_INHERIT, ttl_inherit))
>>>>> goto nla_put_failure;
>>>>>
>>>>> + if (geneve->cfg.tun && nla_put_flag(skb, IFLA_GENEVE_TUN))
>>>>> + goto nla_put_failure;
>>>>> +
>>>>> return 0;
>>>>>
>>>>> nla_put_failure:
>>>>> diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
>>>>> index bd24c7dc10a2..198aefa2c513 100644
>>>>> --- a/include/uapi/linux/if_link.h
>>>>> +++ b/include/uapi/linux/if_link.h
>>>>> @@ -842,6 +842,7 @@ enum {
>>>>> IFLA_GENEVE_LABEL,
>>>>> IFLA_GENEVE_TTL_INHERIT,
>>>>> IFLA_GENEVE_DF,
>>>>> + IFLA_GENEVE_TUN,
>>>> geneve is itself called a tunnel, i wonder if a different name for the
>>>> flag would be more appropriate.
>>> I tried to find a reference to something similar, so went with something like
>>> the tun vs. tap distinction. I was also concerned about the possible
>>> confusion, but it felt clearer than something like L3_INNER_PROTO_MODE.
>>>
>>> I'd happily replace it with a better suggestion.
>> o ok, makes sense. I can't think of anything other than simply
>> IFLA_GENEVE_INNER_PROTO
>>
>> (maybe others have better suggestions)
> My concern with calling it IFLA_GENEVE_INNER_PROTO is that inner_proto is
> used internally to denote the inner proto value.
>
> Would IFLA_GENEVE_INNER_PROTO_INHERIT make sense?
yes, i like that better (and there is precedence to using inherit)
>>
>>>> what is the use case for this ?. is there a RFC reference ?
>>> I stumbled upon this configuration when trying to receive packets from an
>>> AWS "Gateway Load Balancer" which sends IP packets encapsulated in GENEVE [1].
>>>
>>> But to my understanding the RFC allows this so it doesn't seem something
>>> specific to AWS.
>> that makes me wonder if we need a knob atall and if this should be
>> allowed by default.
> I didn't find a way to make tx work without requiring a flag, so I thought
> it'd be better if this mode was enforced in both directions.
ok, in that case flag is ok.
>
>> wonder how other network vendor standard geneve implementations behave
>> by default.
>>
>>
>>> Thanks for the review!
>>>
>>> Eyal.
>>>
>>> [1] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Faws.amazon.com%2Fblogs%2Fnetworking-and-content-delivery%2Fintegrate-your-custom-logic-or-appliance-with-aws-gateway-load-balancer%2F&data=04%7C01%7Croopa%40nvidia.com%7C15818ae5c7f949db55f908da07002ccd%7C43083d15727340c1b7db39efd9ccc17a%7C0%7C0%7C637829994585887100%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=a4hU8aizVq%2Bp4ETdpn4oNIUAkNT%2FPkDiVtTGr8ksBts%3D&reserved=0
>> Thanks for the details.
>>
>>
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