gre_offload: simplify GRE header length calculation in gre_gso_segment()
[firefly-linux-kernel-4.4.55.git] / net / ipv4 / gre_offload.c
index e5d436188464eba55eca773f4fb88fd0f0634e97..29512e3e7e7c6f598854d4d3eafd4e4047fc6440 100644 (file)
@@ -26,8 +26,9 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
 {
        struct sk_buff *segs = ERR_PTR(-EINVAL);
        netdev_features_t enc_features;
-       int ghl = GRE_HEADER_SECTION;
+       int ghl;
        struct gre_base_hdr *greh;
+       u16 mac_offset = skb->mac_header;
        int mac_len = skb->mac_len;
        __be16 protocol = skb->protocol;
        int tnl_hlen;
@@ -48,23 +49,19 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
 
        greh = (struct gre_base_hdr *)skb_transport_header(skb);
 
-       if (greh->flags & GRE_KEY)
-               ghl += GRE_HEADER_SECTION;
-       if (greh->flags & GRE_SEQ)
-               ghl += GRE_HEADER_SECTION;
-       if (greh->flags & GRE_CSUM) {
-               ghl += GRE_HEADER_SECTION;
-               csum = true;
-       } else
-               csum = false;
+       ghl = skb_inner_network_header(skb) - skb_transport_header(skb);
+       if (unlikely(ghl < sizeof(*greh)))
+               goto out;
 
-       /* setup inner skb. */
-       skb->protocol = greh->protocol;
-       skb->encapsulation = 0;
+       csum = !!(greh->flags & GRE_CSUM);
 
        if (unlikely(!pskb_may_pull(skb, ghl)))
                goto out;
 
+       /* setup inner skb. */
+       skb->protocol = greh->protocol;
+       skb->encapsulation = 0;
+
        __skb_pull(skb, ghl);
        skb_reset_mac_header(skb);
        skb_set_network_header(skb, skb_inner_network_offset(skb));
@@ -73,8 +70,10 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
        /* segment inner packet. */
        enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
        segs = skb_mac_gso_segment(skb, enc_features);
-       if (!segs || IS_ERR(segs))
+       if (!segs || IS_ERR(segs)) {
+               skb_gso_error_unwind(skb, protocol, ghl, mac_offset, mac_len);
                goto out;
+       }
 
        skb = segs;
        tnl_hlen = skb_tnl_header_len(skb);
@@ -113,19 +112,182 @@ out:
        return segs;
 }
 
+/* Compute the whole skb csum in s/w and store it, then verify GRO csum
+ * starting from gro_offset.
+ */
+static __sum16 gro_skb_checksum(struct sk_buff *skb)
+{
+       __sum16 sum;
+
+       skb->csum = skb_checksum(skb, 0, skb->len, 0);
+       NAPI_GRO_CB(skb)->csum = csum_sub(skb->csum,
+               csum_partial(skb->data, skb_gro_offset(skb), 0));
+       sum = csum_fold(NAPI_GRO_CB(skb)->csum);
+       if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE)) {
+               if (unlikely(!sum))
+                       netdev_rx_csum_fault(skb->dev);
+       } else
+               skb->ip_summed = CHECKSUM_COMPLETE;
+
+       return sum;
+}
+
+static struct sk_buff **gre_gro_receive(struct sk_buff **head,
+                                       struct sk_buff *skb)
+{
+       struct sk_buff **pp = NULL;
+       struct sk_buff *p;
+       const struct gre_base_hdr *greh;
+       unsigned int hlen, grehlen;
+       unsigned int off;
+       int flush = 1;
+       struct packet_offload *ptype;
+       __be16 type;
+
+       off = skb_gro_offset(skb);
+       hlen = off + sizeof(*greh);
+       greh = skb_gro_header_fast(skb, off);
+       if (skb_gro_header_hard(skb, hlen)) {
+               greh = skb_gro_header_slow(skb, hlen, off);
+               if (unlikely(!greh))
+                       goto out;
+       }
+
+       /* Only support version 0 and K (key), C (csum) flags. Note that
+        * although the support for the S (seq#) flag can be added easily
+        * for GRO, this is problematic for GSO hence can not be enabled
+        * here because a GRO pkt may end up in the forwarding path, thus
+        * requiring GSO support to break it up correctly.
+        */
+       if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
+               goto out;
+
+       type = greh->protocol;
+
+       rcu_read_lock();
+       ptype = gro_find_receive_by_type(type);
+       if (ptype == NULL)
+               goto out_unlock;
+
+       grehlen = GRE_HEADER_SECTION;
+
+       if (greh->flags & GRE_KEY)
+               grehlen += GRE_HEADER_SECTION;
+
+       if (greh->flags & GRE_CSUM)
+               grehlen += GRE_HEADER_SECTION;
+
+       hlen = off + grehlen;
+       if (skb_gro_header_hard(skb, hlen)) {
+               greh = skb_gro_header_slow(skb, hlen, off);
+               if (unlikely(!greh))
+                       goto out_unlock;
+       }
+       if (greh->flags & GRE_CSUM) { /* Need to verify GRE csum first */
+               __sum16 csum = 0;
+
+               if (skb->ip_summed == CHECKSUM_COMPLETE)
+                       csum = csum_fold(NAPI_GRO_CB(skb)->csum);
+               /* Don't trust csum error calculated/reported by h/w */
+               if (skb->ip_summed == CHECKSUM_NONE || csum != 0)
+                       csum = gro_skb_checksum(skb);
+
+               /* GRE CSUM is the 1's complement of the 1's complement sum
+                * of the GRE hdr plus payload so it should add up to 0xffff
+                * (and 0 after csum_fold()) just like the IPv4 hdr csum.
+                */
+               if (csum)
+                       goto out_unlock;
+       }
+       flush = 0;
+
+       for (p = *head; p; p = p->next) {
+               const struct gre_base_hdr *greh2;
+
+               if (!NAPI_GRO_CB(p)->same_flow)
+                       continue;
+
+               /* The following checks are needed to ensure only pkts
+                * from the same tunnel are considered for aggregation.
+                * The criteria for "the same tunnel" includes:
+                * 1) same version (we only support version 0 here)
+                * 2) same protocol (we only support ETH_P_IP for now)
+                * 3) same set of flags
+                * 4) same key if the key field is present.
+                */
+               greh2 = (struct gre_base_hdr *)(p->data + off);
+
+               if (greh2->flags != greh->flags ||
+                   greh2->protocol != greh->protocol) {
+                       NAPI_GRO_CB(p)->same_flow = 0;
+                       continue;
+               }
+               if (greh->flags & GRE_KEY) {
+                       /* compare keys */
+                       if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
+                               NAPI_GRO_CB(p)->same_flow = 0;
+                               continue;
+                       }
+               }
+       }
+
+       skb_gro_pull(skb, grehlen);
+
+       /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
+       skb_gro_postpull_rcsum(skb, greh, grehlen);
+
+       pp = ptype->callbacks.gro_receive(head, skb);
+
+out_unlock:
+       rcu_read_unlock();
+out:
+       NAPI_GRO_CB(skb)->flush |= flush;
+
+       return pp;
+}
+
+static int gre_gro_complete(struct sk_buff *skb, int nhoff)
+{
+       struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
+       struct packet_offload *ptype;
+       unsigned int grehlen = sizeof(*greh);
+       int err = -ENOENT;
+       __be16 type;
+
+       type = greh->protocol;
+       if (greh->flags & GRE_KEY)
+               grehlen += GRE_HEADER_SECTION;
+
+       if (greh->flags & GRE_CSUM)
+               grehlen += GRE_HEADER_SECTION;
+
+       rcu_read_lock();
+       ptype = gro_find_complete_by_type(type);
+       if (ptype != NULL)
+               err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
+
+       rcu_read_unlock();
+       return err;
+}
+
 static const struct net_offload gre_offload = {
        .callbacks = {
                .gso_send_check = gre_gso_send_check,
                .gso_segment = gre_gso_segment,
+               .gro_receive = gre_gro_receive,
+               .gro_complete = gre_gro_complete,
        },
 };
 
-int __init gre_offload_init(void)
+static int __init gre_offload_init(void)
 {
        return inet_add_offload(&gre_offload, IPPROTO_GRE);
 }
 
-void __exit gre_offload_exit(void)
+static void __exit gre_offload_exit(void)
 {
        inet_del_offload(&gre_offload, IPPROTO_GRE);
 }
+
+module_init(gre_offload_init);
+module_exit(gre_offload_exit);