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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>
This commit is contained in:
Willem de Bruijn 2018-04-26 13:42:16 -04:00 committed by David S. Miller
parent 1cd7884dfd
commit ee80d1ebe5
6 changed files with 82 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/skbuff.h
View File

@ -573,6 +573,8 @@ enum {
SKB_GSO_ESP = 1 << 15,
SKB_GSO_UDP = 1 << 16,
SKB_GSO_UDP_L4 = 1 << 17,
};
#if BITS_PER_LONG > 32

4
include/net/udp.h
View File

@ -174,6 +174,10 @@ struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb,
struct udphdr *uh, udp_lookup_t lookup);
int udp_gro_complete(struct sk_buff *skb, int nhoff, udp_lookup_t lookup);
struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
netdev_features_t features,
unsigned int mss, __sum16 check);
static inline struct udphdr *udp_gro_udphdr(struct sk_buff *skb)
{
struct udphdr *uh;

2
net/core/skbuff.c
View File

@ -4940,6 +4940,8 @@ static unsigned int skb_gso_transport_seglen(const struct sk_buff *skb)
thlen = tcp_hdrlen(skb);
} else if (unlikely(skb_is_gso_sctp(skb))) {
thlen = sizeof(struct sctphdr);
} else if (shinfo->gso_type & SKB_GSO_UDP_L4) {
thlen = sizeof(struct udphdr);
}
/* UFO sets gso_size to the size of the fragmentation
* payload, i.e. the size of the L4 (UDP) header is already

53
net/ipv4/udp_offload.c
View File

@ -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;

6
net/ipv6/ip6_offload.c
View File

@ -88,9 +88,11 @@ static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
if (skb->encapsulation &&
skb_shinfo(skb)->gso_type & (SKB_GSO_IPXIP4 | SKB_GSO_IPXIP6))
udpfrag = proto == IPPROTO_UDP && encap;
udpfrag = proto == IPPROTO_UDP && encap &&
(skb_shinfo(skb)->gso_type & SKB_GSO_UDP);
else
udpfrag = proto == IPPROTO_UDP && !skb->encapsulation;
udpfrag = proto == IPPROTO_UDP && !skb->encapsulation &&
(skb_shinfo(skb)->gso_type & SKB_GSO_UDP);
ops = rcu_dereference(inet6_offloads[proto]);
if (likely(ops && ops->callbacks.gso_segment)) {

19
net/ipv6/udp_offload.c
View File

@ -17,6 +17,20 @@
#include <net/ip6_checksum.h>
#include "ip6_offload.h"
static struct sk_buff *__udp6_gso_segment(struct sk_buff *gso_skb,
netdev_features_t features)
{
const struct ipv6hdr *ip6h = ipv6_hdr(gso_skb);
unsigned int mss = skb_shinfo(gso_skb)->gso_size;
if (!can_checksum_protocol(features, htons(ETH_P_IPV6)))
return ERR_PTR(-EIO);
return __udp_gso_segment(gso_skb, features, mss,
udp_v6_check(sizeof(struct udphdr) + mss,
&ip6h->saddr, &ip6h->daddr, 0));
}
static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
netdev_features_t features)
{
@ -42,12 +56,15 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
const struct ipv6hdr *ipv6h;
struct udphdr *uh;
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 __udp6_gso_segment(skb, features);
/* Do software UFO. Complete and fill in the UDP checksum as HW cannot
* do checksum of UDP packets sent as multiple IP fragments.
*/