gue: TX support for using remote checksum offload option

Add if_tunnel flag TUNNEL_ENCAP_FLAG_REMCSUM to configure
remote checksum offload on an IP tunnel. Add logic in gue_build_header
to insert remote checksum offload option.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/fou.h b/include/net/fou.h
index cf4ce8874f925e7ef203fd40bcba272cb0f03ff3..25b26ffcf1df8625d0d5616019417f44e6951db1 100644 (file)
--- a/include/net/fou.h
+++ b/include/net/fou.h
@@ -20,7 +20,19 @@ static size_t fou_encap_hlen(struct ip_tunnel_encap *e)
 
 static size_t gue_encap_hlen(struct ip_tunnel_encap *e)
 {
-       return sizeof(struct udphdr) + sizeof(struct guehdr);
+       size_t len;
+       bool need_priv = false;
+
+       len = sizeof(struct udphdr) + sizeof(struct guehdr);
+
+       if (e->flags & TUNNEL_ENCAP_FLAG_REMCSUM) {
+               len += GUE_PLEN_REMCSUM;
+               need_priv = true;
+       }
+
+       len += need_priv ? GUE_LEN_PRIV : 0;
+
+       return len;
 }
 
 #endif

diff --git a/include/uapi/linux/if_tunnel.h b/include/uapi/linux/if_tunnel.h
index 280d9e092283673c4ac6ef37c3b5ecec2cb406e6..bd3cc11a431f9e5bb01f18d84d3f388915043367 100644 (file)
--- a/include/uapi/linux/if_tunnel.h
+++ b/include/uapi/linux/if_tunnel.h
@@ -69,6 +69,7 @@ enum tunnel_encap_types {
 
 #define TUNNEL_ENCAP_FLAG_CSUM         (1<<0)
 #define TUNNEL_ENCAP_FLAG_CSUM6                (1<<1)
+#define TUNNEL_ENCAP_FLAG_REMCSUM      (1<<2)
 
 /* SIT-mode i_flags */
 #define        SIT_ISATAP      0x0001

diff --git a/net/ipv4/fou.c b/net/ipv4/fou.c
index a3b8c5b36303c1337f5983a1b3b9c289d3827e9d..fb0db99adf9e4eefd5e5e7e231312e82ef04efb5 100644 (file)
--- a/net/ipv4/fou.c
+++ b/net/ipv4/fou.c
@@ -562,11 +562,19 @@ int gue_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
        bool csum = !!(e->flags & TUNNEL_ENCAP_FLAG_CSUM);
        int type = csum ? SKB_GSO_UDP_TUNNEL_CSUM : SKB_GSO_UDP_TUNNEL;
        struct guehdr *guehdr;
-       size_t optlen = 0;
+       size_t hdrlen, optlen = 0;
        __be16 sport;
        void *data;
        bool need_priv = false;
 
+       if ((e->flags & TUNNEL_ENCAP_FLAG_REMCSUM) &&
+           skb->ip_summed == CHECKSUM_PARTIAL) {
+               csum = false;
+               optlen += GUE_PLEN_REMCSUM;
+               type |= SKB_GSO_TUNNEL_REMCSUM;
+               need_priv = true;
+       }
+
        optlen += need_priv ? GUE_LEN_PRIV : 0;
 
        skb = iptunnel_handle_offloads(skb, csum, type);
@@ -578,7 +586,9 @@ int gue_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
        sport = e->sport ? : udp_flow_src_port(dev_net(skb->dev),
                                               skb, 0, 0, false);
 
-       skb_push(skb, sizeof(struct guehdr) + optlen);
+       hdrlen = sizeof(struct guehdr) + optlen;
+
+       skb_push(skb, hdrlen);
 
        guehdr = (struct guehdr *)skb->data;
 
@@ -597,7 +607,26 @@ int gue_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
                *flags = 0;
                data += GUE_LEN_PRIV;
 
-               /* Add private flags */
+               if (type & SKB_GSO_TUNNEL_REMCSUM) {
+                       u16 csum_start = skb_checksum_start_offset(skb);
+                       __be16 *pd = data;
+
+                       if (csum_start < hdrlen)
+                               return -EINVAL;
+
+                       csum_start -= hdrlen;
+                       pd[0] = htons(csum_start);
+                       pd[1] = htons(csum_start + skb->csum_offset);
+
+                       if (!skb_is_gso(skb)) {
+                               skb->ip_summed = CHECKSUM_NONE;
+                               skb->encapsulation = 0;
+                       }
+
+                       *flags |= GUE_PFLAG_REMCSUM;
+                       data += GUE_PLEN_REMCSUM;
+               }
+
        }
 
        fou_build_udp(skb, e, fl4, protocol, sport);