[v2] ipvs: Fix checksumming on GSO of SCTP packets

[PATCH v2] ipvs: Fix checksumming on GSO of SCTP packets

Posted by Ismael Luceno 1 year, 9 months ago

It was observed in the wild that pairs of consecutive packets would leave
the IPVS with the same wrong checksum, and the issue only went away when
disabling GSO.

IPVS needs to avoid computing the SCTP checksum when using GSO.

Fixes: 90017accff61 ("sctp: Add GSO support", 2016-06-02)
Co-developed-by: Firo Yang <firo.yang@suse.com>
Signed-off-by: Ismael Luceno <iluceno@suse.de>
Tested-by: Andreas Taschner <andreas.taschner@suse.com>
CC: Michal Kubeček <mkubecek@suse.com>
CC: Simon Horman <horms@verge.net.au>
CC: Julian Anastasov <ja@ssi.bg>
CC: lvs-devel@vger.kernel.org
CC: netfilter-devel@vger.kernel.org
CC: netdev@vger.kernel.org
CC: coreteam@netfilter.org
---

Notes:
    Changes since v1:
    * Added skb_is_gso before skb_is_gso_sctp.
    * Added "Fixes" tag.

 net/netfilter/ipvs/ip_vs_proto_sctp.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_proto_sctp.c b/net/netfilter/ipvs/ip_vs_proto_sctp.c
index a0921adc31a9..1e689c714127 100644
--- a/net/netfilter/ipvs/ip_vs_proto_sctp.c
+++ b/net/netfilter/ipvs/ip_vs_proto_sctp.c
@@ -126,7 +126,8 @@ sctp_snat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
 	if (sctph->source != cp->vport || payload_csum ||
 	    skb->ip_summed == CHECKSUM_PARTIAL) {
 		sctph->source = cp->vport;
-		sctp_nat_csum(skb, sctph, sctphoff);
+		if (!skb_is_gso(skb) || !skb_is_gso_sctp(skb))
+			sctp_nat_csum(skb, sctph, sctphoff);
 	} else {
 		skb->ip_summed = CHECKSUM_UNNECESSARY;
 	}
@@ -174,7 +175,8 @@ sctp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
 	    (skb->ip_summed == CHECKSUM_PARTIAL &&
 	     !(skb_dst(skb)->dev->features & NETIF_F_SCTP_CRC))) {
 		sctph->dest = cp->dport;
-		sctp_nat_csum(skb, sctph, sctphoff);
+		if (!skb_is_gso(skb) || !skb_is_gso_sctp(skb))
+			sctp_nat_csum(skb, sctph, sctphoff);
 	} else if (skb->ip_summed != CHECKSUM_PARTIAL) {
 		skb->ip_summed = CHECKSUM_UNNECESSARY;
 	}
-- 
2.43.0

Re: [PATCH v2] ipvs: Fix checksumming on GSO of SCTP packets

Posted by Pablo Neira Ayuso 1 year, 9 months ago

On Sun, Apr 21, 2024 at 04:22:32PM +0200, Ismael Luceno wrote:
> It was observed in the wild that pairs of consecutive packets would leave
> the IPVS with the same wrong checksum, and the issue only went away when
> disabling GSO.
> 
> IPVS needs to avoid computing the SCTP checksum when using GSO.

I am placing this into the nf.git tree for submission upstream in the
next pull request, unless stated otherwise.

Thanks.

> Fixes: 90017accff61 ("sctp: Add GSO support", 2016-06-02)
> Co-developed-by: Firo Yang <firo.yang@suse.com>
> Signed-off-by: Ismael Luceno <iluceno@suse.de>
> Tested-by: Andreas Taschner <andreas.taschner@suse.com>
> CC: Michal Kubeček <mkubecek@suse.com>
> CC: Simon Horman <horms@verge.net.au>
> CC: Julian Anastasov <ja@ssi.bg>
> CC: lvs-devel@vger.kernel.org
> CC: netfilter-devel@vger.kernel.org
> CC: netdev@vger.kernel.org
> CC: coreteam@netfilter.org
> ---
> 
> Notes:
>     Changes since v1:
>     * Added skb_is_gso before skb_is_gso_sctp.
>     * Added "Fixes" tag.
> 
>  net/netfilter/ipvs/ip_vs_proto_sctp.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_proto_sctp.c b/net/netfilter/ipvs/ip_vs_proto_sctp.c
> index a0921adc31a9..1e689c714127 100644
> --- a/net/netfilter/ipvs/ip_vs_proto_sctp.c
> +++ b/net/netfilter/ipvs/ip_vs_proto_sctp.c
> @@ -126,7 +126,8 @@ sctp_snat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
>  	if (sctph->source != cp->vport || payload_csum ||
>  	    skb->ip_summed == CHECKSUM_PARTIAL) {
>  		sctph->source = cp->vport;
> -		sctp_nat_csum(skb, sctph, sctphoff);
> +		if (!skb_is_gso(skb) || !skb_is_gso_sctp(skb))
> +			sctp_nat_csum(skb, sctph, sctphoff);
>  	} else {
>  		skb->ip_summed = CHECKSUM_UNNECESSARY;
>  	}
> @@ -174,7 +175,8 @@ sctp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
>  	    (skb->ip_summed == CHECKSUM_PARTIAL &&
>  	     !(skb_dst(skb)->dev->features & NETIF_F_SCTP_CRC))) {
>  		sctph->dest = cp->dport;
> -		sctp_nat_csum(skb, sctph, sctphoff);
> +		if (!skb_is_gso(skb) || !skb_is_gso_sctp(skb))
> +			sctp_nat_csum(skb, sctph, sctphoff);
>  	} else if (skb->ip_summed != CHECKSUM_PARTIAL) {
>  		skb->ip_summed = CHECKSUM_UNNECESSARY;
>  	}
> -- 
> 2.43.0
> 
>

Re: [PATCH v2] ipvs: Fix checksumming on GSO of SCTP packets

Posted by Julian Anastasov 1 year, 9 months ago

	Hello,

On Sun, 21 Apr 2024, Ismael Luceno wrote:

> It was observed in the wild that pairs of consecutive packets would leave
> the IPVS with the same wrong checksum, and the issue only went away when
> disabling GSO.
> 
> IPVS needs to avoid computing the SCTP checksum when using GSO.
> 
> Fixes: 90017accff61 ("sctp: Add GSO support", 2016-06-02)
> Co-developed-by: Firo Yang <firo.yang@suse.com>
> Signed-off-by: Ismael Luceno <iluceno@suse.de>
> Tested-by: Andreas Taschner <andreas.taschner@suse.com>
> CC: Michal Kubeček <mkubecek@suse.com>
> CC: Simon Horman <horms@verge.net.au>
> CC: Julian Anastasov <ja@ssi.bg>
> CC: lvs-devel@vger.kernel.org
> CC: netfilter-devel@vger.kernel.org
> CC: netdev@vger.kernel.org
> CC: coreteam@netfilter.org

	Looks good to me, thanks!

Acked-by: Julian Anastasov <ja@ssi.bg>

	As scripts/checkpatch.pl --strict /tmp/file.patch complains
about Co-developed-by and Signed-off-by lines you may want to
send v3...

> ---
> 
> Notes:
>     Changes since v1:
>     * Added skb_is_gso before skb_is_gso_sctp.
>     * Added "Fixes" tag.
> 
>  net/netfilter/ipvs/ip_vs_proto_sctp.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_proto_sctp.c b/net/netfilter/ipvs/ip_vs_proto_sctp.c
> index a0921adc31a9..1e689c714127 100644
> --- a/net/netfilter/ipvs/ip_vs_proto_sctp.c
> +++ b/net/netfilter/ipvs/ip_vs_proto_sctp.c
> @@ -126,7 +126,8 @@ sctp_snat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
>  	if (sctph->source != cp->vport || payload_csum ||
>  	    skb->ip_summed == CHECKSUM_PARTIAL) {
>  		sctph->source = cp->vport;
> -		sctp_nat_csum(skb, sctph, sctphoff);
> +		if (!skb_is_gso(skb) || !skb_is_gso_sctp(skb))
> +			sctp_nat_csum(skb, sctph, sctphoff);
>  	} else {
>  		skb->ip_summed = CHECKSUM_UNNECESSARY;
>  	}
> @@ -174,7 +175,8 @@ sctp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
>  	    (skb->ip_summed == CHECKSUM_PARTIAL &&
>  	     !(skb_dst(skb)->dev->features & NETIF_F_SCTP_CRC))) {
>  		sctph->dest = cp->dport;
> -		sctp_nat_csum(skb, sctph, sctphoff);
> +		if (!skb_is_gso(skb) || !skb_is_gso_sctp(skb))
> +			sctp_nat_csum(skb, sctph, sctphoff);
>  	} else if (skb->ip_summed != CHECKSUM_PARTIAL) {
>  		skb->ip_summed = CHECKSUM_UNNECESSARY;
>  	}
> -- 
> 2.43.0

Regards

--
Julian Anastasov <ja@ssi.bg>