net: local checksum offload for encapsulation
The arithmetic properties of the ones-complement checksum mean that a
correctly checksummed inner packet, including its checksum, has a ones
complement sum depending only on whatever value was used to initialise
the checksum field before checksumming (in the case of TCP and UDP,
this is the ones complement sum of the pseudo header, complemented).
Consequently, if we are going to offload the inner checksum with
CHECKSUM_PARTIAL, we can compute the outer checksum based only on the
packed data not covered by the inner checksum, and the initial value of
the inner checksum field.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_tunnel_core.c b/net/ipv4/ip_tunnel_core.c
index 859d415..d74ce93 100644
--- a/net/ipv4/ip_tunnel_core.c
+++ b/net/ipv4/ip_tunnel_core.c
@@ -166,20 +166,20 @@
return skb;
}
- /* If packet is not gso and we are resolving any partial checksum,
+ /* If packet is not gso and we are not offloading inner checksum,
* clear encapsulation flag. This allows setting CHECKSUM_PARTIAL
* on the outer header without confusing devices that implement
* NETIF_F_IP_CSUM with encapsulation.
*/
- if (csum_help)
- skb->encapsulation = 0;
-
if (skb->ip_summed == CHECKSUM_PARTIAL && csum_help) {
+ skb->encapsulation = 0;
err = skb_checksum_help(skb);
if (unlikely(err))
goto error;
- } else if (skb->ip_summed != CHECKSUM_PARTIAL)
+ } else if (skb->ip_summed != CHECKSUM_PARTIAL) {
skb->ip_summed = CHECKSUM_NONE;
+ skb->encapsulation = 0;
+ }
return skb;
error:
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index ac3cedb..a59341c 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -848,16 +848,18 @@
{
struct udphdr *uh = udp_hdr(skb);
- if (nocheck)
+ if (nocheck) {
uh->check = 0;
- else if (skb_is_gso(skb))
+ } else if (skb_is_gso(skb)) {
uh->check = ~udp_v4_check(len, saddr, daddr, 0);
- else if (skb_dst(skb) && skb_dst(skb)->dev &&
- (skb_dst(skb)->dev->features &
- (NETIF_F_IP_CSUM | NETIF_F_HW_CSUM))) {
-
- BUG_ON(skb->ip_summed == CHECKSUM_PARTIAL);
-
+ } else if (skb->ip_summed == CHECKSUM_PARTIAL) {
+ uh->check = 0;
+ uh->check = udp_v4_check(len, saddr, daddr, lco_csum(skb));
+ if (uh->check == 0)
+ uh->check = CSUM_MANGLED_0;
+ } else if (skb_dst(skb) && skb_dst(skb)->dev &&
+ (skb_dst(skb)->dev->features &
+ (NETIF_F_IP_CSUM | NETIF_F_HW_CSUM))) {
skb->ip_summed = CHECKSUM_PARTIAL;
skb->csum_start = skb_transport_header(skb) - skb->head;
skb->csum_offset = offsetof(struct udphdr, check);
@@ -865,8 +867,6 @@
} else {
__wsum csum;
- BUG_ON(skb->ip_summed == CHECKSUM_PARTIAL);
-
uh->check = 0;
csum = skb_checksum(skb, 0, len, 0);
uh->check = udp_v4_check(len, saddr, daddr, csum);
diff --git a/net/ipv6/ip6_checksum.c b/net/ipv6/ip6_checksum.c
index 9a4d732..4924bd7 100644
--- a/net/ipv6/ip6_checksum.c
+++ b/net/ipv6/ip6_checksum.c
@@ -98,11 +98,13 @@
uh->check = 0;
else if (skb_is_gso(skb))
uh->check = ~udp_v6_check(len, saddr, daddr, 0);
- else if (skb_dst(skb) && skb_dst(skb)->dev &&
- (skb_dst(skb)->dev->features & NETIF_F_IPV6_CSUM)) {
-
- BUG_ON(skb->ip_summed == CHECKSUM_PARTIAL);
-
+ else if (skb->ip_summed == CHECKSUM_PARTIAL) {
+ uh->check = 0;
+ uh->check = udp_v6_check(len, saddr, daddr, lco_csum(skb));
+ if (uh->check == 0)
+ uh->check = CSUM_MANGLED_0;
+ } else if (skb_dst(skb) && skb_dst(skb)->dev &&
+ (skb_dst(skb)->dev->features & NETIF_F_IPV6_CSUM)) {
skb->ip_summed = CHECKSUM_PARTIAL;
skb->csum_start = skb_transport_header(skb) - skb->head;
skb->csum_offset = offsetof(struct udphdr, check);
@@ -110,8 +112,6 @@
} else {
__wsum csum;
- BUG_ON(skb->ip_summed == CHECKSUM_PARTIAL);
-
uh->check = 0;
csum = skb_checksum(skb, 0, len, 0);
uh->check = udp_v6_check(len, saddr, daddr, csum);
