tunneling: Add generic Tunnel segmentation.

Adds generic tunneling offloading support for IPv4-UDP based
tunnels.
GSO type is added to request this offload for a skb.
netdev feature NETIF_F_UDP_TUNNEL is added for hardware offloaded
udp-tunnel support. Currently no device supports this feature,
software offload is used.

This can be used by tunneling protocols like VXLAN.

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

6 files changed, 105 insertions, 27 deletions

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 3e9b2c3e30f0..adc1351e6873 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -78,6 +78,7 @@ static const char netdev_features_strings[NETDEV_FEATURE_COUNT][ETH_GSTRING_LEN]
         [NETIF_F_TSO6_BIT] =             "tx-tcp6-segmentation",
         [NETIF_F_FSO_BIT] =              "tx-fcoe-segmentation",
         [NETIF_F_GSO_GRE_BIT] =          "tx-gre-segmentation",
+        [NETIF_F_GSO_UDP_TUNNEL_BIT] =   "tx-udp_tnl-segmentation",
 
         [NETIF_F_FCOE_CRC_BIT] =         "tx-checksum-fcoe-crc",
         [NETIF_F_SCTP_CSUM_BIT] =        "tx-checksum-sctp",
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index dc3f677360a5..9e5882caf8a7 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1283,6 +1283,7 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb,
         int ihl;
         int id;
         unsigned int offset = 0;
+        bool tunnel;
 
         if (unlikely(skb_shinfo(skb)->gso_type &
                      ~(SKB_GSO_TCPV4 |
@@ -1290,6 +1291,7 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb,
                        SKB_GSO_DODGY |
                        SKB_GSO_TCP_ECN |
                        SKB_GSO_GRE |
+                       SKB_GSO_UDP_TUNNEL |
                        0)))
                 goto out;
 
@@ -1304,6 +1306,8 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb,
         if (unlikely(!pskb_may_pull(skb, ihl)))
                 goto out;
 
+        tunnel = !!skb->encapsulation;
+
         __skb_pull(skb, ihl);
         skb_reset_transport_header(skb);
         iph = ip_hdr(skb);
@@ -1323,7 +1327,7 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb,
         skb = segs;
         do {
                 iph = ip_hdr(skb);
-                if (proto == IPPROTO_UDP) {
+                if (!tunnel && proto == IPPROTO_UDP) {
                         iph->id = htons(id);
                         iph->frag_off = htons(offset >> 3);
                         if (skb->next != NULL)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 47e854fcae24..8d14573ade77 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3044,6 +3044,7 @@ struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
                                SKB_GSO_TCP_ECN |
                                SKB_GSO_TCPV6 |
                                SKB_GSO_GRE |
+                               SKB_GSO_UDP_TUNNEL |
                                0) ||
                              !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))))
                         goto out;
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 265c42cf963c..41760e043bf5 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2272,31 +2272,88 @@ void __init udp_init(void)
 
 int udp4_ufo_send_check(struct sk_buff *skb)
 {
-        const struct iphdr *iph;
-        struct udphdr *uh;
-
-        if (!pskb_may_pull(skb, sizeof(*uh)))
+        if (!pskb_may_pull(skb, sizeof(struct udphdr)))
                 return -EINVAL;
 
-        iph = ip_hdr(skb);
-        uh = udp_hdr(skb);
+        if (likely(!skb->encapsulation)) {
+                const struct iphdr *iph;
+                struct udphdr *uh;
 
-        uh->check = ~csum_tcpudp_magic(iph->saddr, iph->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;
+                iph = ip_hdr(skb);
+                uh = udp_hdr(skb);
+
+                uh->check = ~csum_tcpudp_magic(iph->saddr, iph->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_udp_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;
+                int udp_offset = outer_hlen - tnl_hlen;
+
+                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);
+
+                /* csum segment if tunnel sets skb with csum. */
+                if (unlikely(uh->check)) {
+                        struct iphdr *iph = ip_hdr(skb);
+
+                        uh->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
+                                                       skb->len - udp_offset,
+                                                       IPPROTO_UDP, 0);
+                        uh->check = csum_fold(skb_checksum(skb, udp_offset,
+                                                           skb->len - udp_offset, 0));
+                        if (uh->check == 0)
+                                uh->check = CSUM_MANGLED_0;
+
+                }
+                skb->ip_summed = CHECKSUM_NONE;
+        } while ((skb = skb->next));
+out:
+        return segs;
+}
+
 struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
         netdev_features_t features)
 {
         struct sk_buff *segs = ERR_PTR(-EINVAL);
         unsigned int mss;
-        int offset;
-        __wsum csum;
-
         mss = skb_shinfo(skb)->gso_size;
         if (unlikely(skb->len <= mss))
                 goto out;
@@ -2306,6 +2363,7 @@ struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
                 int type = skb_shinfo(skb)->gso_type;
 
                 if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY |
+                                      SKB_GSO_UDP_TUNNEL |
                                       SKB_GSO_GRE) ||
                              !(type & (SKB_GSO_UDP))))
                         goto out;
@@ -2316,20 +2374,27 @@ struct sk_buff *udp4_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;
-
         /* Fragment the skb. IP headers of the fragments are updated in
          * inet_gso_segment()
          */
-        segs = skb_segment(skb, features);
+        if (skb->encapsulation && skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL)
+                segs = skb_udp_tunnel_segment(skb, features);
+        else {
+                int offset;
+                __wsum csum;
+
+                /* 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;
+
+                segs = skb_segment(skb, features);
+        }
 out:
         return segs;
 }
-
diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
index 7a0d25a5479c..71b766ee821d 100644
--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c
@@ -97,6 +97,7 @@ static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
                        SKB_GSO_DODGY |
                        SKB_GSO_TCP_ECN |
                        SKB_GSO_GRE |
+                       SKB_GSO_UDP_TUNNEL |
                        SKB_GSO_TCPV6 |
                        0)))
                 goto out;
diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c
index cf05cf073c51..3bb3a891a424 100644
--- a/net/ipv6/udp_offload.c
+++ b/net/ipv6/udp_offload.c
@@ -21,6 +21,10 @@ 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;
 
@@ -56,7 +60,9 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
                 /* Packet is from an untrusted source, reset gso_segs. */
                 int type = skb_shinfo(skb)->gso_type;
 
-                if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY |
+                if (unlikely(type & ~(SKB_GSO_UDP |
+                                      SKB_GSO_DODGY |
+                                      SKB_GSO_UDP_TUNNEL |
                                       SKB_GSO_GRE) ||
                              !(type & (SKB_GSO_UDP))))
                         goto out;