netdev - Re: [PATCH iproute2-next v1 1/1 v1] ip-link: add support for nolocalbypass in vxlan

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Date:   Wed, 05 Apr 2023 13:21:17 +0800
From:   Vladimir Nikishkin <vladimir@...ishkin.pw>
To:     Hangbin Liu <liuhangbin@...il.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com,
        eng.alaamohamedsoliman.am@...il.com, gnault@...hat.com,
        razor@...ckwall.org, idosch@...dia.com, eyal.birger@...il.com,
        jtoppins@...hat.com
Subject: Re: [PATCH iproute2-next v1 1/1 v1] ip-link: add support for
 nolocalbypass in vxlan


Hangbin Liu <liuhangbin@...il.com> writes:

> Hi Vladimir,
>
> For the subject prefix, [PATCH iproute2-next] is enough for the v1 patch.
>
> On Thu, Mar 23, 2023 at 02:04:51PM +0800, Vladimir Nikishkin wrote:
>> Add userspace support for the nolocalbypass vxlan netlink
>> attribute. With nolocalbypass, if an entry is pointing to the
>> local machine, but the system driver is not listening on this
>> port, the driver will not drop packets, but will forward them
>> to the userspace network stack instead.
>> 
>> This commit has a corresponding patch in the net-next list.
>> 
>> Signed-off-by: Vladimir Nikishkin <vladimir@...ishkin.pw>
>> ---
>>  include/uapi/linux/if_link.h |  1 +
>>  ip/iplink_vxlan.c            | 18 ++++++++++++++++++
>>  man/man8/ip-link.8.in        |  8 ++++++++
>>  3 files changed, 27 insertions(+)
>> 
>> diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
>> index d61bd32d..fd390b40 100644
>> --- a/include/uapi/linux/if_link.h
>> +++ b/include/uapi/linux/if_link.h
>> @@ -824,6 +824,7 @@ enum {
>>  	IFLA_VXLAN_TTL_INHERIT,
>>  	IFLA_VXLAN_DF,
>>  	IFLA_VXLAN_VNIFILTER, /* only applicable with COLLECT_METADATA mode */
>> +	IFLA_VXLAN_LOCALBYPASS,
>>  	__IFLA_VXLAN_MAX
>>  };
>>  #define IFLA_VXLAN_MAX	(__IFLA_VXLAN_MAX - 1)
>
> There is no need to include the uapi header. Stephen will sync it with upstream.
>
> Hi Stephen, should we add this note to the README.devel?
>

Without this change, my code does not compile. I ended up modifying the
header, but not adding it to git. Is this the correct way of doing it?

>> diff --git a/ip/iplink_vxlan.c b/ip/iplink_vxlan.c
>> index c7e0e1c4..17fa5cf7 100644
>> --- a/ip/iplink_vxlan.c
>> +++ b/ip/iplink_vxlan.c
>> @@ -276,6 +276,12 @@ static int vxlan_parse_opt(struct link_util *lu, int argc, char **argv,
>>  		} else if (!matches(*argv, "noudpcsum")) {
>>  			check_duparg(&attrs, IFLA_VXLAN_UDP_CSUM, *argv, *argv);
>>  			addattr8(n, 1024, IFLA_VXLAN_UDP_CSUM, 0);
>> +		} else if (!matches(*argv, "localbypass")) {
>> +			check_duparg(&attrs, IFLA_VXLAN_LOCALBYPASS, *argv, *argv);
>> +			addattr8(n, 1024, IFLA_VXLAN_LOCALBYPASS, 1);
>> +		} else if (!matches(*argv, "nolocalbypass")) {
>> +			check_duparg(&attrs, IFLA_VXLAN_LOCALBYPASS, *argv, *argv);
>> +			addattr8(n, 1024, IFLA_VXLAN_LOCALBYPASS, 0);
>
> matches is deparated, please use strcmp instead.

Why is strcmp recommended, not strncmp? I remember strcmp being frowned
upon for some potential memory bounds violations.

>
> Thanks
> Hangbin


-- 
Your sincerely,
Vladimir Nikishkin (MiEr, lockywolf)
(Laptop)
--
Fastmail.