4 files changed, 20 insertions, 36 deletions

diff --git a/include/net/sctp/checksum.h b/include/net/sctp/checksum.h
index 78b88aa8c810..483e6303458d 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(skb->data + offset,
+                                       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 3c0da8728036..23e596e438b3 100644
--- a/net/netfilter/ipvs/ip_vs_proto_sctp.c
+++ b/net/netfilter/ipvs/ip_vs_proto_sctp.c
@@ -66,15 +66,7 @@ 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);
-
+        sctph->checksum = sctp_compute_cksum(skb, sctphoff);
         skb->ip_summed = CHECKSUM_UNNECESSARY;
 }
 
@@ -151,10 +143,7 @@ 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 +157,7 @@ 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, sctphoff);
 
         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 396e55d46f90..754536f2c674 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 7993495a4c0f..fa91aff02388 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);
-
-        val = sctp_end_cksum(tmp);
+        __le32 val = sctp_compute_cksum(skb, 0);
 
         if (val != cmp) {
                 /* CRC failure, dump it. */