[SCTP]: Don't do CRC32C checksum over loopback.

Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 29 insertions, 22 deletions

diff --git a/net/sctp/input.c b/net/sctp/input.c
index 70d6606e2812..42b66e74bbb5 100644
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -141,7 +141,8 @@ int sctp_rcv(struct sk_buff *skb)
         __skb_pull(skb, skb->h.raw - skb->data);
         if (skb->len < sizeof(struct sctphdr))
                 goto discard_it;
-        if (sctp_rcv_checksum(skb) < 0)
+        if ((skb->ip_summed != CHECKSUM_UNNECESSARY) &&
+            (sctp_rcv_checksum(skb) < 0))
                 goto discard_it;
 
         skb_pull(skb, sizeof(struct sctphdr));
diff --git a/net/sctp/output.c b/net/sctp/output.c
index 437cba7260a4..cdc5a3936766 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -295,14 +295,14 @@ int sctp_packet_transmit(struct sctp_packet *packet)
         struct sctp_transport *tp = packet->transport;
         struct sctp_association *asoc = tp->asoc;
         struct sctphdr *sh;
-        __u32 crc32;
+        __u32 crc32 = 0;
         struct sk_buff *nskb;
         struct sctp_chunk *chunk, *tmp;
         struct sock *sk;
         int err = 0;
         int padding;            /* How much padding do we need?  */
         __u8 has_data = 0;
-        struct dst_entry *dst;
+        struct dst_entry *dst = tp->dst;
 
         SCTP_DEBUG_PRINTK("%s: packet:%p\n", __FUNCTION__, packet);
 
@@ -327,6 +327,19 @@ int sctp_packet_transmit(struct sctp_packet *packet)
          */
         skb_set_owner_w(nskb, sk);
 
+        /* The 'obsolete' field of dst is set to 2 when a dst is freed. */
+        if (!dst || (dst->obsolete > 1)) {
+                dst_release(dst);
+                sctp_transport_route(tp, NULL, sctp_sk(sk));
+                if (asoc && (asoc->param_flags & SPP_PMTUD_ENABLE)) {
+                        sctp_assoc_sync_pmtu(asoc);
+                }
+        }
+        nskb->dst = dst_clone(tp->dst);
+        if (!nskb->dst)
+                goto no_route;
+        dst = nskb->dst;
+
         /* Build the SCTP header.  */
         sh = (struct sctphdr *)skb_push(nskb, sizeof(struct sctphdr));
         sh->source = htons(packet->source_port);
@@ -350,7 +363,8 @@ int sctp_packet_transmit(struct sctp_packet *packet)
          * Note: Adler-32 is no longer applicable, as has been replaced
          * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
          */
-        crc32 = sctp_start_cksum((__u8 *)sh, sizeof(struct sctphdr));
+        if (!(dst->dev->features & NETIF_F_NO_CSUM))
+                crc32 = sctp_start_cksum((__u8 *)sh, sizeof(struct sctphdr));
 
         /**
          * 6.10 Bundling
@@ -402,9 +416,14 @@ int sctp_packet_transmit(struct sctp_packet *packet)
                 if (padding)
                         memset(skb_put(chunk->skb, padding), 0, padding);
 
-                crc32 = sctp_update_copy_cksum(skb_put(nskb, chunk->skb->len),
-                                               chunk->skb->data,
-                                               chunk->skb->len, crc32);
+                if (dst->dev->features & NETIF_F_NO_CSUM)
+                        memcpy(skb_put(nskb, chunk->skb->len),
+                               chunk->skb->data, chunk->skb->len);
+                else
+                        crc32 = sctp_update_copy_cksum(skb_put(nskb,
+                                                        chunk->skb->len),
+                                                chunk->skb->data,
+                                                chunk->skb->len, crc32);
 
                 SCTP_DEBUG_PRINTK("%s %p[%s] %s 0x%x, %s %d, %s %d, %s %d\n",
                                   "*** Chunk", chunk,
@@ -427,7 +446,8 @@ int sctp_packet_transmit(struct sctp_packet *packet)
         }
 
         /* Perform final transformation on checksum. */
-        crc32 = sctp_end_cksum(crc32);
+        if (!(dst->dev->features & NETIF_F_NO_CSUM))
+                crc32 = sctp_end_cksum(crc32);
 
         /* 3) Put the resultant value into the checksum field in the
          *    common header, and leave the rest of the bits unchanged.
@@ -477,20 +497,6 @@ int sctp_packet_transmit(struct sctp_packet *packet)
                 }
         }
 
-        dst = tp->dst;
-        /* The 'obsolete' field of dst is set to 2 when a dst is freed. */
-        if (!dst || (dst->obsolete > 1)) {
-                dst_release(dst);
-                sctp_transport_route(tp, NULL, sctp_sk(sk));
-                if (asoc->param_flags & SPP_PMTUD_ENABLE) {
-                        sctp_assoc_sync_pmtu(asoc);
-                }
-        }
-
-        nskb->dst = dst_clone(tp->dst);
-        if (!nskb->dst)
-                goto no_route;
-
         SCTP_DEBUG_PRINTK("***sctp_transmit_packet*** skb len %d\n",
                           nskb->len);