[PATCH net-next v2] net: geneve: accept every ethertype

[PATCH net-next v2] net: geneve: accept every ethertype

[Josef Miegl]

The Geneve encapsulation, as defined in RFC 8926, has a Protocol Type
field, which states the Ethertype of the payload appearing after the
Geneve header.

Commit 435fe1c0c1f7 ("net: geneve: support IPv4/IPv6 as inner protocol")
introduced a new IFLA_GENEVE_INNER_PROTO_INHERIT flag that allowed the
use of other Ethertypes than Ethernet. However, it did not get rid of a
restriction that prohibits receiving payloads other than Ethernet,
instead the commit white-listed additional Ethertypes, IPv4 and IPv6.

This patch removes this restriction, making it possible to receive any
Ethertype as a payload, if the IFLA_GENEVE_INNER_PROTO_INHERIT flag is
set.

The restriction was set in place back in commit 0b5e8b8eeae4
("net: Add Geneve tunneling protocol driver"), which implemented a
protocol layer driver for Geneve to be used with Open vSwitch. The
relevant discussion about introducing the Ethertype white-list can be
found here:
https://lore.kernel.org/netdev/CAEP_g=_1q3ACX5NTHxLDnysL+dTMUVzdLpgw1apLKEdDSWPztw@mail.gmail.com/

<quote>
>> +       if (unlikely(geneveh->proto_type != htons(ETH_P_TEB)))
>
> Why? I thought the point of geneve carrying protocol field was to
> allow protocols other than Ethernet... is this temporary maybe?

Yes, it is temporary. Currently OVS only handles Ethernet packets but
this restriction can be lifted once we have a consumer that is capable
of handling other protocols.
</quote>

This white-list was then ported to a generic Geneve netdevice in commit
371bd1061d29 ("geneve: Consolidate Geneve functionality in single
module."). Preserving the Ethertype white-list at this point made sense,
as the Geneve device could send out only Ethernet payloads anyways.

However, now that the Geneve netdevice supports encapsulating other
payloads with IFLA_GENEVE_INNER_PROTO_INHERIT and we have a consumer
capable of other protocols, it seems appropriate to lift the restriction
and allow any Geneve payload to be received.

Signed-off-by: Josef Miegl <josef@miegl.cz>
---
 drivers/net/geneve.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
index 89ff7f8e8c7e..32684e94eb4f 100644
--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -365,13 +365,6 @@ static int geneve_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
 	if (unlikely(geneveh->ver != GENEVE_VER))
 		goto drop;
 
-	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;
-
 	gs = rcu_dereference_sk_user_data(sk);
 	if (!gs)
 		goto drop;
@@ -380,6 +373,8 @@ static int geneve_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
 	if (!geneve)
 		goto drop;
 
+	inner_proto = geneveh->proto_type;
+
 	if (unlikely((!geneve->cfg.inner_proto_inherit &&
 		      inner_proto != htons(ETH_P_TEB)))) {
 		geneve->dev->stats.rx_dropped++;
-- 
2.37.1

Re: [PATCH net-next v2] net: geneve: accept every ethertype

[Simon Horman]

On Sun, Mar 19, 2023 at 11:09:54PM +0100, Josef Miegl wrote:
> The Geneve encapsulation, as defined in RFC 8926, has a Protocol Type
> field, which states the Ethertype of the payload appearing after the
> Geneve header.
> 
> Commit 435fe1c0c1f7 ("net: geneve: support IPv4/IPv6 as inner protocol")
> introduced a new IFLA_GENEVE_INNER_PROTO_INHERIT flag that allowed the
> use of other Ethertypes than Ethernet. However, it did not get rid of a
> restriction that prohibits receiving payloads other than Ethernet,
> instead the commit white-listed additional Ethertypes, IPv4 and IPv6.
> 
> This patch removes this restriction, making it possible to receive any
> Ethertype as a payload, if the IFLA_GENEVE_INNER_PROTO_INHERIT flag is
> set.
> 
> The restriction was set in place back in commit 0b5e8b8eeae4
> ("net: Add Geneve tunneling protocol driver"), which implemented a
> protocol layer driver for Geneve to be used with Open vSwitch. The
> relevant discussion about introducing the Ethertype white-list can be
> found here:
> https://lore.kernel.org/netdev/CAEP_g=_1q3ACX5NTHxLDnysL+dTMUVzdLpgw1apLKEdDSWPztw@mail.gmail.com/
> 
> <quote>
> >> +       if (unlikely(geneveh->proto_type != htons(ETH_P_TEB)))
> >
> > Why? I thought the point of geneve carrying protocol field was to
> > allow protocols other than Ethernet... is this temporary maybe?
> 
> Yes, it is temporary. Currently OVS only handles Ethernet packets but
> this restriction can be lifted once we have a consumer that is capable
> of handling other protocols.
> </quote>
> 
> This white-list was then ported to a generic Geneve netdevice in commit
> 371bd1061d29 ("geneve: Consolidate Geneve functionality in single
> module."). Preserving the Ethertype white-list at this point made sense,
> as the Geneve device could send out only Ethernet payloads anyways.

I'm not sure if it ought to be fixed, but checkpatch complains that:

:379: ERROR: Please use git commit description style 'commit <12+ chars of sha1> ("<title line>")' - ie: 'commit 371bd1061d29 ("geneve: Consolidate Geneve functionality in single module.")'
This white-list was then ported to a generic Geneve netdevice in commit

> However, now that the Geneve netdevice supports encapsulating other
> payloads with IFLA_GENEVE_INNER_PROTO_INHERIT and we have a consumer
> capable of other protocols, it seems appropriate to lift the restriction
> and allow any Geneve payload to be received.
> 
> Signed-off-by: Josef Miegl <josef@miegl.cz>

Above nit not withstanding, and in keeping with the discussion of v1,
I am happy with this patch.

Reviewed-by: Simon Horman <simon.horman@corigine.com>

...

Re: [PATCH net-next v2] net: geneve: accept every ethertype

[Eyal Birger]

On Mon, Mar 20, 2023 at 12:10 AM Josef Miegl <josef@miegl.cz> wrote:
>
> The Geneve encapsulation, as defined in RFC 8926, has a Protocol Type
> field, which states the Ethertype of the payload appearing after the
> Geneve header.
>
> Commit 435fe1c0c1f7 ("net: geneve: support IPv4/IPv6 as inner protocol")
> introduced a new IFLA_GENEVE_INNER_PROTO_INHERIT flag that allowed the
> use of other Ethertypes than Ethernet. However, it did not get rid of a
> restriction that prohibits receiving payloads other than Ethernet,
> instead the commit white-listed additional Ethertypes, IPv4 and IPv6.
>
> This patch removes this restriction, making it possible to receive any
> Ethertype as a payload, if the IFLA_GENEVE_INNER_PROTO_INHERIT flag is
> set.
>
> The restriction was set in place back in commit 0b5e8b8eeae4
> ("net: Add Geneve tunneling protocol driver"), which implemented a
> protocol layer driver for Geneve to be used with Open vSwitch. The
> relevant discussion about introducing the Ethertype white-list can be
> found here:
> https://lore.kernel.org/netdev/CAEP_g=_1q3ACX5NTHxLDnysL+dTMUVzdLpgw1apLKEdDSWPztw@mail.gmail.com/
>
> <quote>
> >> +       if (unlikely(geneveh->proto_type != htons(ETH_P_TEB)))
> >
> > Why? I thought the point of geneve carrying protocol field was to
> > allow protocols other than Ethernet... is this temporary maybe?
>
> Yes, it is temporary. Currently OVS only handles Ethernet packets but
> this restriction can be lifted once we have a consumer that is capable
> of handling other protocols.
> </quote>
>
> This white-list was then ported to a generic Geneve netdevice in commit
> 371bd1061d29 ("geneve: Consolidate Geneve functionality in single
> module."). Preserving the Ethertype white-list at this point made sense,
> as the Geneve device could send out only Ethernet payloads anyways.
>
> However, now that the Geneve netdevice supports encapsulating other
> payloads with IFLA_GENEVE_INNER_PROTO_INHERIT and we have a consumer
> capable of other protocols, it seems appropriate to lift the restriction
> and allow any Geneve payload to be received.
>
> Signed-off-by: Josef Miegl <josef@miegl.cz>
> ---
>  drivers/net/geneve.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
> index 89ff7f8e8c7e..32684e94eb4f 100644
> --- a/drivers/net/geneve.c
> +++ b/drivers/net/geneve.c
> @@ -365,13 +365,6 @@ static int geneve_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
>         if (unlikely(geneveh->ver != GENEVE_VER))
>                 goto drop;
>
> -       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;
> -
>         gs = rcu_dereference_sk_user_data(sk);
>         if (!gs)
>                 goto drop;
> @@ -380,6 +373,8 @@ static int geneve_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
>         if (!geneve)
>                 goto drop;
>
> +       inner_proto = geneveh->proto_type;
> +
>         if (unlikely((!geneve->cfg.inner_proto_inherit &&
>                       inner_proto != htons(ETH_P_TEB)))) {
>                 geneve->dev->stats.rx_dropped++;
> --
> 2.37.1
>

Reviewed-by: Eyal Birger <eyal.birger@gmail.com>

Re: [PATCH net-next v2] net: geneve: accept every ethertype

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Paolo Abeni <pabeni@redhat.com>:

On Sun, 19 Mar 2023 23:09:54 +0100 you wrote:
> The Geneve encapsulation, as defined in RFC 8926, has a Protocol Type
> field, which states the Ethertype of the payload appearing after the
> Geneve header.
> 
> Commit 435fe1c0c1f7 ("net: geneve: support IPv4/IPv6 as inner protocol")
> introduced a new IFLA_GENEVE_INNER_PROTO_INHERIT flag that allowed the
> use of other Ethertypes than Ethernet. However, it did not get rid of a
> restriction that prohibits receiving payloads other than Ethernet,
> instead the commit white-listed additional Ethertypes, IPv4 and IPv6.
> 
> [...]

Here is the summary with links:
  - [net-next,v2] net: geneve: accept every ethertype
    https://git.kernel.org/netdev/net-next/c/251d5a2813f9

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html