ipv6: Add generic UDP Tunnel segmentation

Similar to commit 731362674580cb0c696cd1b1a03d8461a10cf90a
(tunneling: Add generic Tunnel segmentation)

This patch adds generic tunneling offloading support for
IPv6-UDP based tunnels.

This can be used by tunneling protocols like VXLAN.

Cc: Jesse Gross <jesse@nicira.com>
Cc: Pravin B Shelar <pshelar@nicira.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 111 insertions, 52 deletions

diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
index a263b990ee11..d82de7228100 100644
--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c
@@ -91,6 +91,7 @@ static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
         unsigned int unfrag_ip6hlen;
         u8 *prevhdr;
         int offset = 0;
+        bool tunnel;
 
         if (unlikely(skb_shinfo(skb)->gso_type &
                      ~(SKB_GSO_UDP |
@@ -106,6 +107,7 @@ static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
         if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
                 goto out;
 
+        tunnel = skb->encapsulation;
         ipv6h = ipv6_hdr(skb);
         __skb_pull(skb, sizeof(*ipv6h));
         segs = ERR_PTR(-EPROTONOSUPPORT);
@@ -126,7 +128,7 @@ static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
                 ipv6h = ipv6_hdr(skb);
                 ipv6h->payload_len = htons(skb->len - skb->mac_len -
                                            sizeof(*ipv6h));
-                if (proto == IPPROTO_UDP) {
+                if (!tunnel && proto == IPPROTO_UDP) {
                         unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
                         fptr = (struct frag_hdr *)(skb_network_header(skb) +
                                 unfrag_ip6hlen);
diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c
index 5d1b8d7ac993..7e5e5acc9619 100644
--- a/net/ipv6/udp_offload.c
+++ b/net/ipv6/udp_offload.c
@@ -21,26 +21,79 @@ static int udp6_ufo_send_check(struct sk_buff *skb)
         const struct ipv6hdr *ipv6h;
         struct udphdr *uh;
 
-        /* UDP Tunnel offload on ipv6 is not yet supported. */
-        if (skb->encapsulation)
-                return -EINVAL;
-
         if (!pskb_may_pull(skb, sizeof(*uh)))
                 return -EINVAL;
 
-        ipv6h = ipv6_hdr(skb);
-        uh = udp_hdr(skb);
+        if (likely(!skb->encapsulation)) {
+                ipv6h = ipv6_hdr(skb);
+                uh = udp_hdr(skb);
+
+                uh->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr, skb->len,
+                                             IPPROTO_UDP, 0);
+                skb->csum_start = skb_transport_header(skb) - skb->head;
+                skb->csum_offset = offsetof(struct udphdr, check);
+                skb->ip_summed = CHECKSUM_PARTIAL;
+        }
 
-        uh->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr, skb->len,
-                                     IPPROTO_UDP, 0);
-        skb->csum_start = skb_transport_header(skb) - skb->head;
-        skb->csum_offset = offsetof(struct udphdr, check);
-        skb->ip_summed = CHECKSUM_PARTIAL;
         return 0;
 }
 
+static struct sk_buff *skb_udp6_tunnel_segment(struct sk_buff *skb,
+                                               netdev_features_t features)
+{
+        struct sk_buff *segs = ERR_PTR(-EINVAL);
+        int mac_len = skb->mac_len;
+        int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
+        int outer_hlen;
+        netdev_features_t enc_features;
+
+        if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
+                goto out;
+
+        skb->encapsulation = 0;
+        __skb_pull(skb, tnl_hlen);
+        skb_reset_mac_header(skb);
+        skb_set_network_header(skb, skb_inner_network_offset(skb));
+        skb->mac_len = skb_inner_network_offset(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))
+                goto out;
+
+        outer_hlen = skb_tnl_header_len(skb);
+        skb = segs;
+        do {
+                struct udphdr *uh;
+                struct ipv6hdr *ipv6h;
+                int udp_offset = outer_hlen - tnl_hlen;
+                u32 len;
+
+                skb->mac_len = mac_len;
+
+                skb_push(skb, outer_hlen);
+                skb_reset_mac_header(skb);
+                skb_set_network_header(skb, mac_len);
+                skb_set_transport_header(skb, udp_offset);
+                uh = udp_hdr(skb);
+                uh->len = htons(skb->len - udp_offset);
+                ipv6h = ipv6_hdr(skb);
+                len = skb->len - udp_offset;
+
+                uh->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
+                                             len, IPPROTO_UDP, 0);
+                uh->check = csum_fold(skb_checksum(skb, udp_offset, len, 0));
+                if (uh->check == 0)
+                        uh->check = CSUM_MANGLED_0;
+                skb->ip_summed = CHECKSUM_NONE;
+        } while ((skb = skb->next));
+out:
+        return segs;
+}
+
 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
-        netdev_features_t features)
+                                         netdev_features_t features)
 {
         struct sk_buff *segs = ERR_PTR(-EINVAL);
         unsigned int mss;
@@ -75,47 +128,51 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
                 goto out;
         }
 
-        /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
-         * do checksum of UDP packets sent as multiple IP fragments.
-         */
-        offset = skb_checksum_start_offset(skb);
-        csum = skb_checksum(skb, offset, skb->len - offset, 0);
-        offset += skb->csum_offset;
-        *(__sum16 *)(skb->data + offset) = csum_fold(csum);
-        skb->ip_summed = CHECKSUM_NONE;
-
-        /* Check if there is enough headroom to insert fragment header. */
-        tnl_hlen = skb_tnl_header_len(skb);
-        if (skb_headroom(skb) < (tnl_hlen + frag_hdr_sz)) {
-                if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
-                        goto out;
+        if (skb->encapsulation && skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL)
+                segs = skb_udp6_tunnel_segment(skb, features);
+        else {
+                /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
+                 * do checksum of UDP packets sent as multiple IP fragments.
+                 */
+                offset = skb_checksum_start_offset(skb);
+                csum = skb_checksum(skb, offset, skb->len - offset, 0);
+                offset += skb->csum_offset;
+                *(__sum16 *)(skb->data + offset) = csum_fold(csum);
+                skb->ip_summed = CHECKSUM_NONE;
+
+                /* Check if there is enough headroom to insert fragment header. */
+                tnl_hlen = skb_tnl_header_len(skb);
+                if (skb_headroom(skb) < (tnl_hlen + frag_hdr_sz)) {
+                        if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
+                                goto out;
+                }
+
+                /* Find the unfragmentable header and shift it left by frag_hdr_sz
+                 * bytes to insert fragment header.
+                 */
+                unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
+                nexthdr = *prevhdr;
+                *prevhdr = NEXTHDR_FRAGMENT;
+                unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
+                             unfrag_ip6hlen + tnl_hlen;
+                packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
+                memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
+
+                SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
+                skb->mac_header -= frag_hdr_sz;
+                skb->network_header -= frag_hdr_sz;
+
+                fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
+                fptr->nexthdr = nexthdr;
+                fptr->reserved = 0;
+                ipv6_select_ident(fptr, (struct rt6_info *)skb_dst(skb));
+
+                /* Fragment the skb. ipv6 header and the remaining fields of the
+                 * fragment header are updated in ipv6_gso_segment()
+                 */
+                segs = skb_segment(skb, features);
         }
 
-        /* Find the unfragmentable header and shift it left by frag_hdr_sz
-         * bytes to insert fragment header.
-         */
-        unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
-        nexthdr = *prevhdr;
-        *prevhdr = NEXTHDR_FRAGMENT;
-        unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
-                     unfrag_ip6hlen + tnl_hlen;
-        packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
-        memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
-
-        SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
-        skb->mac_header -= frag_hdr_sz;
-        skb->network_header -= frag_hdr_sz;
-
-        fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
-        fptr->nexthdr = nexthdr;
-        fptr->reserved = 0;
-        ipv6_select_ident(fptr, (struct rt6_info *)skb_dst(skb));
-
-        /* Fragment the skb. ipv6 header and the remaining fields of the
-         * fragment header are updated in ipv6_gso_segment()
-         */
-        segs = skb_segment(skb, features);
-
 out:
         return segs;
 }