[PATCH net v2] calipso: update payload_len when removing the CALIPSO option

[Paolo Abeni]

On 10/14/26 16:02, Paul Moore wrote:
> On Fri, Oct 9, 2026 at 11:32 AM <sashiko-bot at kernel.org> wrote:
>>
>> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
>> - [High] ipv6: calipso_skbuff_delattr corrupts MAC header on bridged packets
>> --
>>
>> commit 9797bee2d14350b4afedb726df3172b004b7badd
>> Author: Joas Antonio dos Santos <joasantonio108 at gmail.com>
>>
>> calipso: update payload_len when removing the CALIPSO option
>>
>> This commit updates calipso_skbuff_delattr() to adjust the IPv6 payload
>> length after removing a CALIPSO option. The patch prevents forwarded packets
>> from being dropped as truncated by subtracting the removed length, while
>> leaving BIG TCP packets unchanged.
>>
>>> diff --git a/net/ipv6/calipso.c b/net/ipv6/calipso.c
>>> index c6a34334e657e..5a42db4f87472 100644
>>> --- a/net/ipv6/calipso.c
>>> +++ b/net/ipv6/calipso.c
>>> @@ -1428,6 +1428,10 @@ static int calipso_skbuff_delattr(struct sk_buff *skb)
>>>                skb_pull(skb, delta);
>>>                memmove((char *)ip6_hdr + delta, ip6_hdr, size);
>>>                skb_reset_network_header(skb);
>>
>> [Severity: High]
>> When a bridged IPv6 packet with a CALIPSO option is forwarded, br_netfilter
>> feeds it to the NF_INET_FORWARD hook where SELinux may call
>> calipso_skbuff_delattr() in net/ipv6/calipso.c. Does shifting the IPv6 header
>> forward by delta bytes here without repositioning the MAC header create a gap
>> that corrupts the MAC header on bridged packets?
> 
> I haven't chased down the bridging code to confirm if the problem
> identified by Sashiko is true, but I do think that in the bridging
> case we don't want to change the label on the packet as we might do in
> the routing case (depending on the runtime config).
> 
> This would need to be tested, but I believe we could simply add a
> nf_bridge_info_exists() check to selinux_ip_forward() prior to calling
> into selinux_netlbl_skbuff_setsid().  We would need to add dummy
> nf_bridge_info_exists() when CONFIG_BRIDGE_NETFILTER=n to
> netfilter_bridge.h but I can't imagine the netdev folks being opposed
> to such a change; I'm sure they will let us know either way.
The above looks like a pre-exiting issue, the patch itself looks
correct, right?

/P