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* [net-next] net/sctp: Refactor SCTP skb checksum computation
@ 2013-07-23  4:30 Joe Stringer
  2013-07-23  7:14 ` Julian Anastasov
  0 siblings, 1 reply; 3+ messages in thread
From: Joe Stringer @ 2013-07-23  4:30 UTC (permalink / raw)
  To: davem
  Cc: netdev, netfilter-devel, lvs-devel, pablo, ja, horms, jesse,
	Joe Stringer

This patch consolidates the SCTP checksum calculation code from various
places to a single new function, sctp_compute_cksum(skb, offset).

Signed-off-by: Joe Stringer <joe@wand.net.nz>
---
 include/net/sctp/checksum.h           |   15 +++++++++++++++
 net/netfilter/ipvs/ip_vs_proto_sctp.c |   23 ++++-------------------
 net/netfilter/nf_nat_proto_sctp.c     |    8 +-------
 net/sctp/input.c                      |   10 +---------
 4 files changed, 21 insertions(+), 35 deletions(-)

diff --git a/include/net/sctp/checksum.h b/include/net/sctp/checksum.h
index 0cb08e6..8675564 100644
--- a/include/net/sctp/checksum.h
+++ b/include/net/sctp/checksum.h
@@ -85,4 +85,19 @@ static inline __le32 sctp_end_cksum(__u32 crc32)
 	return cpu_to_le32(~crc32);
 }
 
+/* Calculate the CRC32C checksum of an SCTP packet.  */
+static inline __le32 sctp_compute_cksum(const struct sk_buff *skb,
+					unsigned int offset)
+{
+	const struct sk_buff *iter;
+
+	__u32 crc32 = sctp_start_cksum((__u8 *)sctp_hdr(skb),
+				       skb_headlen(skb) - offset);
+	skb_walk_frags(skb, iter)
+		crc32 = sctp_update_cksum((__u8 *) iter->data,
+					  skb_headlen(iter), crc32);
+
+	return sctp_end_cksum(crc32);
+}
+
 #endif /* __sctp_checksum_h__ */
diff --git a/net/netfilter/ipvs/ip_vs_proto_sctp.c b/net/netfilter/ipvs/ip_vs_proto_sctp.c
index 3c0da87..b2e422d 100644
--- a/net/netfilter/ipvs/ip_vs_proto_sctp.c
+++ b/net/netfilter/ipvs/ip_vs_proto_sctp.c
@@ -66,15 +66,9 @@ sctp_conn_schedule(int af, struct sk_buff *skb, struct ip_vs_proto_data *pd,
 static void sctp_nat_csum(struct sk_buff *skb, sctp_sctphdr_t *sctph,
 			  unsigned int sctphoff)
 {
-	__u32 crc32;
-	struct sk_buff *iter;
-
-	crc32 = sctp_start_cksum((__u8 *)sctph, skb_headlen(skb) - sctphoff);
-	skb_walk_frags(skb, iter)
-		crc32 = sctp_update_cksum((u8 *) iter->data,
-					  skb_headlen(iter), crc32);
-	sctph->checksum = sctp_end_cksum(crc32);
+	__le32 crc32 = sctp_compute_cksum(skb, sctphoff);
 
+	sctph->checksum = crc32;
 	skb->ip_summed = CHECKSUM_UNNECESSARY;
 }
 
@@ -151,10 +145,7 @@ sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
 {
 	unsigned int sctphoff;
 	struct sctphdr *sh, _sctph;
-	struct sk_buff *iter;
-	__le32 cmp;
-	__le32 val;
-	__u32 tmp;
+	__le32 cmp, val;
 
 #ifdef CONFIG_IP_VS_IPV6
 	if (af == AF_INET6)
@@ -168,13 +159,7 @@ sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
 		return 0;
 
 	cmp = sh->checksum;
-
-	tmp = sctp_start_cksum((__u8 *) sh, skb_headlen(skb));
-	skb_walk_frags(skb, iter)
-		tmp = sctp_update_cksum((__u8 *) iter->data,
-					skb_headlen(iter), tmp);
-
-	val = sctp_end_cksum(tmp);
+	val = sctp_compute_cksum(skb, 0);
 
 	if (val != cmp) {
 		/* CRC failure, dump it. */
diff --git a/net/netfilter/nf_nat_proto_sctp.c b/net/netfilter/nf_nat_proto_sctp.c
index 396e55d..754536f 100644
--- a/net/netfilter/nf_nat_proto_sctp.c
+++ b/net/netfilter/nf_nat_proto_sctp.c
@@ -34,9 +34,7 @@ sctp_manip_pkt(struct sk_buff *skb,
 	       const struct nf_conntrack_tuple *tuple,
 	       enum nf_nat_manip_type maniptype)
 {
-	struct sk_buff *frag;
 	sctp_sctphdr_t *hdr;
-	__u32 crc32;
 
 	if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
 		return false;
@@ -51,11 +49,7 @@ sctp_manip_pkt(struct sk_buff *skb,
 		hdr->dest = tuple->dst.u.sctp.port;
 	}
 
-	crc32 = sctp_start_cksum((u8 *)hdr, skb_headlen(skb) - hdroff);
-	skb_walk_frags(skb, frag)
-		crc32 = sctp_update_cksum((u8 *)frag->data, skb_headlen(frag),
-					  crc32);
-	hdr->checksum = sctp_end_cksum(crc32);
+	hdr->checksum = sctp_compute_cksum(skb, hdroff);
 
 	return true;
 }
diff --git a/net/sctp/input.c b/net/sctp/input.c
index 3fa4d85..944f70e 100644
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -87,15 +87,7 @@ static inline int sctp_rcv_checksum(struct net *net, struct sk_buff *skb)
 {
 	struct sctphdr *sh = sctp_hdr(skb);
 	__le32 cmp = sh->checksum;
-	struct sk_buff *list;
-	__le32 val;
-	__u32 tmp = sctp_start_cksum((__u8 *)sh, skb_headlen(skb));
-
-	skb_walk_frags(skb, list)
-		tmp = sctp_update_cksum((__u8 *)list->data, skb_headlen(list),
-					tmp);

^ permalink raw reply related	[flat|nested] 3+ messages in thread
* Re: [net-next] net/sctp: Refactor SCTP skb checksum computation
  2013-07-23  4:30 [net-next] net/sctp: Refactor SCTP skb checksum computation Joe Stringer
@ 2013-07-23  7:14 ` Julian Anastasov
  2013-07-25  1:18   ` Joe Stringer
  0 siblings, 1 reply; 3+ messages in thread
From: Julian Anastasov @ 2013-07-23  7:14 UTC (permalink / raw)
  To: Joe Stringer
  Cc: davem, netdev, netfilter-devel, lvs-devel, pablo, horms, jesse


	Hello,

On Tue, 23 Jul 2013, Joe Stringer wrote:

> This patch consolidates the SCTP checksum calculation code from various
> places to a single new function, sctp_compute_cksum(skb, offset).
> 
> Signed-off-by: Joe Stringer <joe@wand.net.nz>
> ---
>  include/net/sctp/checksum.h           |   15 +++++++++++++++
>  net/netfilter/ipvs/ip_vs_proto_sctp.c |   23 ++++-------------------
>  net/netfilter/nf_nat_proto_sctp.c     |    8 +-------
>  net/sctp/input.c                      |   10 +---------
>  4 files changed, 21 insertions(+), 35 deletions(-)
> 
> diff --git a/include/net/sctp/checksum.h b/include/net/sctp/checksum.h
> index 0cb08e6..8675564 100644
> --- a/include/net/sctp/checksum.h
> +++ b/include/net/sctp/checksum.h
> @@ -85,4 +85,19 @@ static inline __le32 sctp_end_cksum(__u32 crc32)
>  	return cpu_to_le32(~crc32);
>  }
>  
> +/* Calculate the CRC32C checksum of an SCTP packet.  */
> +static inline __le32 sctp_compute_cksum(const struct sk_buff *skb,
> +					unsigned int offset)
> +{
> +	const struct sk_buff *iter;
> +
> +	__u32 crc32 = sctp_start_cksum((__u8 *)sctp_hdr(skb),
> +				       skb_headlen(skb) - offset);

	sctp_hdr() is valid in INPUT hook after commit
21d1196a35f5686c4323e42a62fdb4b23b0ab4a3 (ipv4: set transport header
earlier) but I'm not sure for the OUTPUT hook where
IPVS is working. I guess the same is valid for Netfilter.

	IPVS uses skb_network_header(skb) + offset but
I guess it can work with skb->data, just like Netfilter:

	__u32 crc32 = sctp_start_cksum(skb->data + offset,

	This should work also in SCTP where skb->data points
to the SCTP header when sctp_rcv_checksum() is called.

> +	skb_walk_frags(skb, iter)
> +		crc32 = sctp_update_cksum((__u8 *) iter->data,
> +					  skb_headlen(iter), crc32);
> +
> +	return sctp_end_cksum(crc32);
> +}
> +
>  #endif /* __sctp_checksum_h__ */
> diff --git a/net/netfilter/ipvs/ip_vs_proto_sctp.c b/net/netfilter/ipvs/ip_vs_proto_sctp.c
> index 3c0da87..b2e422d 100644
> --- a/net/netfilter/ipvs/ip_vs_proto_sctp.c
> +++ b/net/netfilter/ipvs/ip_vs_proto_sctp.c
> @@ -66,15 +66,9 @@ sctp_conn_schedule(int af, struct sk_buff *skb, struct ip_vs_proto_data *pd,
>  static void sctp_nat_csum(struct sk_buff *skb, sctp_sctphdr_t *sctph,
>  			  unsigned int sctphoff)
>  {
> -	__u32 crc32;
> -	struct sk_buff *iter;
> -
> -	crc32 = sctp_start_cksum((__u8 *)sctph, skb_headlen(skb) - sctphoff);
> -	skb_walk_frags(skb, iter)
> -		crc32 = sctp_update_cksum((u8 *) iter->data,
> -					  skb_headlen(iter), crc32);
> -	sctph->checksum = sctp_end_cksum(crc32);
> +	__le32 crc32 = sctp_compute_cksum(skb, sctphoff);

	crc32 var is not needed anymore, eg:

	sctph->checksum = sctp_compute_cksum(skb, sctphoff);

> +	sctph->checksum = crc32;
>  	skb->ip_summed = CHECKSUM_UNNECESSARY;
>  }
>  
> @@ -151,10 +145,7 @@ sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
>  {
>  	unsigned int sctphoff;
>  	struct sctphdr *sh, _sctph;
> -	struct sk_buff *iter;
> -	__le32 cmp;
> -	__le32 val;
> -	__u32 tmp;
> +	__le32 cmp, val;
>  
>  #ifdef CONFIG_IP_VS_IPV6
>  	if (af == AF_INET6)
> @@ -168,13 +159,7 @@ sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
>  		return 0;
>  
>  	cmp = sh->checksum;
> -
> -	tmp = sctp_start_cksum((__u8 *) sh, skb_headlen(skb));
> -	skb_walk_frags(skb, iter)
> -		tmp = sctp_update_cksum((__u8 *) iter->data,
> -					skb_headlen(iter), tmp);
> -
> -	val = sctp_end_cksum(tmp);
> +	val = sctp_compute_cksum(skb, 0);

	The original code has bug here, still the code
was never used because there are no IPVS apps with
SCTP support. You can safely use sctphoff here, not 0, eg:

	val = sctp_compute_cksum(skb, sctphoff);

>  	if (val != cmp) {
>  		/* CRC failure, dump it. */

Regards

--
Julian Anastasov <ja@ssi.bg>

^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: [net-next] net/sctp: Refactor SCTP skb checksum computation
  2013-07-23  7:14 ` Julian Anastasov
@ 2013-07-25  1:18   ` Joe Stringer
  0 siblings, 0 replies; 3+ messages in thread
From: Joe Stringer @ 2013-07-25  1:18 UTC (permalink / raw)
  To: Julian Anastasov
  Cc: Joe Stringer, davem, netdev, netfilter-devel, lvs-devel, pablo,
	Simon Horman, Jesse Gross

Thanks for the quick response. I'll fix up these issues and repost.

On Tue, Jul 23, 2013 at 4:14 PM, Julian Anastasov <ja@ssi.bg> wrote:
>
>         Hello,
>
> On Tue, 23 Jul 2013, Joe Stringer wrote:
>
>> This patch consolidates the SCTP checksum calculation code from various
>> places to a single new function, sctp_compute_cksum(skb, offset).
>>
>> Signed-off-by: Joe Stringer <joe@wand.net.nz>
>> ---
>>  include/net/sctp/checksum.h           |   15 +++++++++++++++
>>  net/netfilter/ipvs/ip_vs_proto_sctp.c |   23 ++++-------------------
>>  net/netfilter/nf_nat_proto_sctp.c     |    8 +-------
>>  net/sctp/input.c                      |   10 +---------
>>  4 files changed, 21 insertions(+), 35 deletions(-)
>>
>> diff --git a/include/net/sctp/checksum.h b/include/net/sctp/checksum.h
>> index 0cb08e6..8675564 100644
>> --- a/include/net/sctp/checksum.h
>> +++ b/include/net/sctp/checksum.h
>> @@ -85,4 +85,19 @@ static inline __le32 sctp_end_cksum(__u32 crc32)
>>       return cpu_to_le32(~crc32);
>>  }
>>
>> +/* Calculate the CRC32C checksum of an SCTP packet.  */
>> +static inline __le32 sctp_compute_cksum(const struct sk_buff *skb,
>> +                                     unsigned int offset)
>> +{
>> +     const struct sk_buff *iter;
>> +
>> +     __u32 crc32 = sctp_start_cksum((__u8 *)sctp_hdr(skb),
>> +                                    skb_headlen(skb) - offset);
>
>         sctp_hdr() is valid in INPUT hook after commit
> 21d1196a35f5686c4323e42a62fdb4b23b0ab4a3 (ipv4: set transport header
> earlier) but I'm not sure for the OUTPUT hook where
> IPVS is working. I guess the same is valid for Netfilter.
>
>         IPVS uses skb_network_header(skb) + offset but
> I guess it can work with skb->data, just like Netfilter:
>
>         __u32 crc32 = sctp_start_cksum(skb->data + offset,
>
>         This should work also in SCTP where skb->data points
> to the SCTP header when sctp_rcv_checksum() is called.
>
>> +     skb_walk_frags(skb, iter)
>> +             crc32 = sctp_update_cksum((__u8 *) iter->data,
>> +                                       skb_headlen(iter), crc32);
>> +
>> +     return sctp_end_cksum(crc32);
>> +}
>> +
>>  #endif /* __sctp_checksum_h__ */
>> diff --git a/net/netfilter/ipvs/ip_vs_proto_sctp.c b/net/netfilter/ipvs/ip_vs_proto_sctp.c
>> index 3c0da87..b2e422d 100644
>> --- a/net/netfilter/ipvs/ip_vs_proto_sctp.c
>> +++ b/net/netfilter/ipvs/ip_vs_proto_sctp.c
>> @@ -66,15 +66,9 @@ sctp_conn_schedule(int af, struct sk_buff *skb, struct ip_vs_proto_data *pd,
>>  static void sctp_nat_csum(struct sk_buff *skb, sctp_sctphdr_t *sctph,
>>                         unsigned int sctphoff)
>>  {
>> -     __u32 crc32;
>> -     struct sk_buff *iter;
>> -
>> -     crc32 = sctp_start_cksum((__u8 *)sctph, skb_headlen(skb) - sctphoff);
>> -     skb_walk_frags(skb, iter)
>> -             crc32 = sctp_update_cksum((u8 *) iter->data,
>> -                                       skb_headlen(iter), crc32);
>> -     sctph->checksum = sctp_end_cksum(crc32);
>> +     __le32 crc32 = sctp_compute_cksum(skb, sctphoff);
>
>         crc32 var is not needed anymore, eg:
>
>         sctph->checksum = sctp_compute_cksum(skb, sctphoff);
>
>> +     sctph->checksum = crc32;
>>       skb->ip_summed = CHECKSUM_UNNECESSARY;
>>  }
>>
>> @@ -151,10 +145,7 @@ sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
>>  {
>>       unsigned int sctphoff;
>>       struct sctphdr *sh, _sctph;
>> -     struct sk_buff *iter;
>> -     __le32 cmp;
>> -     __le32 val;
>> -     __u32 tmp;
>> +     __le32 cmp, val;
>>
>>  #ifdef CONFIG_IP_VS_IPV6
>>       if (af == AF_INET6)
>> @@ -168,13 +159,7 @@ sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
>>               return 0;
>>
>>       cmp = sh->checksum;
>> -
>> -     tmp = sctp_start_cksum((__u8 *) sh, skb_headlen(skb));
>> -     skb_walk_frags(skb, iter)
>> -             tmp = sctp_update_cksum((__u8 *) iter->data,
>> -                                     skb_headlen(iter), tmp);
>> -
>> -     val = sctp_end_cksum(tmp);
>> +     val = sctp_compute_cksum(skb, 0);
>
>         The original code has bug here, still the code
> was never used because there are no IPVS apps with
> SCTP support. You can safely use sctphoff here, not 0, eg:
>
>         val = sctp_compute_cksum(skb, sctphoff);
>
>>       if (val != cmp) {
>>               /* CRC failure, dump it. */
>
> Regards
>
> --
> Julian Anastasov <ja@ssi.bg>

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2013-07-25  1:18 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2013-07-23  4:30 [net-next] net/sctp: Refactor SCTP skb checksum computation Joe Stringer
2013-07-23  7:14 ` Julian Anastasov
2013-07-25  1:18   ` Joe Stringer

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