udp: add udp gso
Implement generic segmentation offload support for udp datagrams. A
follow-up patch adds support to the protocol stack to generate such
packets.
UDP GSO is not UFO. UFO fragments a single large datagram. GSO splits
a large payload into a number of discrete UDP datagrams.
The implementation adds a GSO type SKB_UDP_GSO_L4 to differentiate it
from UFO (SKB_UDP_GSO).
IPPROTO_UDPLITE is excluded, as that protocol has no gso handler
registered.
[ Export __udp_gso_segment for ipv6. -DaveM ]
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index ea6e6e7..6c2b764 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -187,6 +187,54 @@ struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
}
EXPORT_SYMBOL(skb_udp_tunnel_segment);
+struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
+ netdev_features_t features,
+ unsigned int mss, __sum16 check)
+{
+ struct sk_buff *segs, *seg;
+ unsigned int hdrlen;
+ struct udphdr *uh;
+
+ if (gso_skb->len <= sizeof(*uh) + mss)
+ return ERR_PTR(-EINVAL);
+
+ hdrlen = gso_skb->data - skb_mac_header(gso_skb);
+ skb_pull(gso_skb, sizeof(*uh));
+
+ segs = skb_segment(gso_skb, features);
+ if (unlikely(IS_ERR_OR_NULL(segs)))
+ return segs;
+
+ for (seg = segs; seg; seg = seg->next) {
+ uh = udp_hdr(seg);
+ uh->len = htons(seg->len - hdrlen);
+ uh->check = check;
+
+ /* last packet can be partial gso_size */
+ if (!seg->next)
+ csum_replace2(&uh->check, htons(mss),
+ htons(seg->len - hdrlen - sizeof(*uh)));
+ }
+
+ return segs;
+}
+EXPORT_SYMBOL_GPL(__udp_gso_segment);
+
+static struct sk_buff *__udp4_gso_segment(struct sk_buff *gso_skb,
+ netdev_features_t features)
+{
+ const struct iphdr *iph = ip_hdr(gso_skb);
+ unsigned int mss = skb_shinfo(gso_skb)->gso_size;
+
+ if (!can_checksum_protocol(features, htons(ETH_P_IP)))
+ return ERR_PTR(-EIO);
+
+ return __udp_gso_segment(gso_skb, features, mss,
+ udp_v4_check(sizeof(struct udphdr) + mss,
+ iph->saddr, iph->daddr, 0));
+}
+EXPORT_SYMBOL_GPL(__udp4_gso_segment);
+
static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
netdev_features_t features)
{
@@ -203,12 +251,15 @@ static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
goto out;
}
- if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP))
+ if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_UDP | SKB_GSO_UDP_L4)))
goto out;
if (!pskb_may_pull(skb, sizeof(struct udphdr)))
goto out;
+ if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)
+ return __udp4_gso_segment(skb, features);
+
mss = skb_shinfo(skb)->gso_size;
if (unlikely(skb->len <= mss))
goto out;
