[PATCH net-next 0/2] net/sched: act_csum: add support for SCTP checksum

This series extends current act_csum functionality to allow computation of
SCTP checksums. Patch 1 ensures LIBCRC32C will be selected if NET_ACT_CSUM
is selected. Patch 2 extends act_csum to handle IPPROTO_SCTP protocol in
IPv4/IPv6 header, and eventually compute the CRC32c value.

Davide Caratti (2):
  net/sched: Kconfig: select LIBCRC32C if NET_ACT_CSUM is selected
  net/sched: act_csum: compute crc32c on SCTP packets

 include/uapi/linux/tc_act/tc_csum.h |  3 ++-
 net/sched/Kconfig                   |  1 +
 net/sched/act_csum.c                | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+), 1 deletion(-)

-- 
2.7.4

LIBCRC32C is needed to compute crc32c on SCTP packets.

Signed-off-by: Davide Caratti <redacted>
---
 net/sched/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/sched/Kconfig b/net/sched/Kconfig
index 87956a7..a9aa38d 100644
--- a/net/sched/Kconfig
+++ b/net/sched/Kconfig

@@ -707,6 +707,7 @@ config NET_ACT_SKBEDIT
 config NET_ACT_CSUM
         tristate "Checksum Updating"
         depends on NET_CLS_ACT && INET
+        select LIBCRC32C
         ---help---
 	  Say Y here to update some common checksum after some direct
 	  packet alterations.

-- 
2.7.4

modify act_csum to compute crc32c on IPv4/IPv6 packets having SCTP in
their payload, and extend UAPI definitions accordingly.

Signed-off-by: Davide Caratti <redacted>
---
 include/uapi/linux/tc_act/tc_csum.h |  3 ++-
 net/sched/act_csum.c                | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/tc_act/tc_csum.h b/include/uapi/linux/tc_act/tc_csum.h
index 8ac8041..58d457f 100644
--- a/include/uapi/linux/tc_act/tc_csum.h
+++ b/include/uapi/linux/tc_act/tc_csum.h

@@ -21,7 +21,8 @@ enum {
 	TCA_CSUM_UPDATE_FLAG_IGMP    = 4,
 	TCA_CSUM_UPDATE_FLAG_TCP     = 8,
 	TCA_CSUM_UPDATE_FLAG_UDP     = 16,
-	TCA_CSUM_UPDATE_FLAG_UDPLITE = 32
+	TCA_CSUM_UPDATE_FLAG_UDPLITE = 32,
+	TCA_CSUM_UPDATE_FLAG_SCTP    = 64
 };
 
 struct tc_csum {

diff --git a/net/sched/act_csum.c b/net/sched/act_csum.c
index a0edd80..620ac9b 100644
--- a/net/sched/act_csum.c
+++ b/net/sched/act_csum.c

@@ -30,6 +30,7 @@
 #include <net/tcp.h>
 #include <net/udp.h>
 #include <net/ip6_checksum.h>
+#include <net/sctp/checksum.h>
 
 #include <net/act_api.h>
 

@@ -322,6 +323,25 @@ static int tcf_csum_ipv6_udp(struct sk_buff *skb, unsigned int ihl,
 	return 1;
 }
 
+static int tcf_csum_sctp(struct sk_buff *skb, unsigned int ihl,
+			 unsigned int ipl)
+{
+	struct sctphdr *sctph;
+
+	if (skb_is_gso(skb) && skb_shinfo(skb)->gso_type & SKB_GSO_SCTP)
+		return 1;
+
+	sctph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*sctph));
+	if (!sctph)
+		return 0;
+
+	sctph->checksum = sctp_compute_cksum(skb,
+					     skb_network_offset(skb) + ihl);
+	skb->ip_summed = CHECKSUM_NONE;
+
+	return 1;
+}
+
 static int tcf_csum_ipv4(struct sk_buff *skb, u32 update_flags)
 {
 	const struct iphdr *iph;

@@ -365,6 +385,12 @@ static int tcf_csum_ipv4(struct sk_buff *skb, u32 update_flags)
 					       ntohs(iph->tot_len), 1))
 				goto fail;
 		break;
+	case IPPROTO_SCTP:
+		if (update_flags & TCA_CSUM_UPDATE_FLAG_SCTP)
+			if (!tcf_csum_sctp(skb, iph->ihl * 4,
+					   ntohs(iph->tot_len)))
+				goto fail;
+		break;
 	}
 
 	if (update_flags & TCA_CSUM_UPDATE_FLAG_IPV4HDR) {

@@ -481,6 +507,12 @@ static int tcf_csum_ipv6(struct sk_buff *skb, u32 update_flags)
 						       pl + sizeof(*ip6h), 1))
 					goto fail;
 			goto done;
+		case IPPROTO_SCTP:
+			if (update_flags & TCA_CSUM_UPDATE_FLAG_SCTP)
+				if (!tcf_csum_sctp(skb, hl,
+						   pl + sizeof(*ip6h)))
+					goto fail;
+			goto done;
 		default:
 			goto ignore_skb;
 		}

-- 
2.7.4

Le 05/01/2017 à 17:59, Davide Caratti a écrit :

nit: please put a comma after the '64' so that the next person who adds a flag
will not have to touch that line.

[snip]

nit: one 'if' only?
		if (update_flags & TCA_CSUM_UPDATE_FLAG_SCTP &&
		    !tcf_csum_sctp(skb, iph->ihl * 4, ntohs(iph->tot_len))

Same here.


Regards,
Nicolas

On Fri, 2017-01-06 at 10:23 +0100, Nicolas Dichtel wrote:

Le 05/01/2017 à 17:59, Davide Caratti a écrit :

quoted

@@ -21,7 +21,8 @@ enum {

 	TCA_CSUM_UPDATE_FLAG_IGMP    = 4,
 	TCA_CSUM_UPDATE_FLAG_TCP     = 8,
 	TCA_CSUM_UPDATE_FLAG_UDP     = 16,
-	TCA_CSUM_UPDATE_FLAG_UDPLITE = 32
+	TCA_CSUM_UPDATE_FLAG_UDPLITE = 32,
+	TCA_CSUM_UPDATE_FLAG_SCTP    = 64

nit: please put a comma after the '64' so that the next person who adds
a flag
will not have to touch that line.

ok,

quoted

@@ -365,6 +385,12 @@ static int tcf_csum_ipv4(struct sk_buff *skb, u32

update_flags)
 					       ntohs(iph->tot_len),
1))
 				goto fail;
 		break;
+	case IPPROTO_SCTP:
+		if (update_flags & TCA_CSUM_UPDATE_FLAG_SCTP)
+			if (!tcf_csum_sctp(skb, iph->ihl * 4,
+					   ntohs(iph->tot_len)))

nit: one 'if' only?
		if (update_flags & TCA_CSUM_UPDATE_FLAG_SCTP &&
		    !tcf_csum_sctp(skb, iph->ihl * 4, ntohs(iph->tot_len))

ok,

quoted

@@ -481,6 +507,12 @@ static int tcf_csum_ipv6(struct sk_buff *skb, u32

update_flags)
 						       pl +
sizeof(*ip6h), 1))
 					goto fail;
 			goto done;
+		case IPPROTO_SCTP:
+			if (update_flags & TCA_CSUM_UPDATE_FLAG_SCTP)
+				if (!tcf_csum_sctp(skb, hl,
+						   pl +
sizeof(*ip6h)))

Same here.

ok,

Regards,
Nicolas

hello Nicolas,
thank you for the attention! I will apply the changes you suggested and
repost a v2.

regards,