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ipv6: update skb->csum when CE mark is propagated 

When a tunnel decapsulates the outer header, it has to comply
with RFC 6080 and eventually propagate CE mark into inner header.

It turns out IP6_ECN_set_ce() does not correctly update skb->csum
for CHECKSUM_COMPLETE packets, triggering infamous "hw csum failure"
messages and stack traces.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2016-01-15 04:56:56 -08:00 committed by David S. Miller
parent 113c74d83e
commit 34ae6a1aa0
2 changed files with 17 additions and 4 deletions
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19
include/net/inet_ecn.h
View File

@ -111,11 +111,24 @@ static inline void ipv4_copy_dscp(unsigned int dscp, struct iphdr *inner)
struct ipv6hdr;
static inline int IP6_ECN_set_ce(struct ipv6hdr *iph)
/* Note:
* IP_ECN_set_ce() has to tweak IPV4 checksum when setting CE,
* meaning both changes have no effect on skb->csum if/when CHECKSUM_COMPLETE
* In IPv6 case, no checksum compensates the change in IPv6 header,
* so we have to update skb->csum.
*/
static inline int IP6_ECN_set_ce(struct sk_buff *skb, struct ipv6hdr *iph)
{
__be32 from, to;
if (INET_ECN_is_not_ect(ipv6_get_dsfield(iph)))
return 0;
*(__be32*)iph |= htonl(INET_ECN_CE << 20);
from = *(__be32 *)iph;
to = from | htonl(INET_ECN_CE << 20);
*(__be32 *)iph = to;
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->csum = csum_add(csum_sub(skb->csum, from), to);
return 1;
}
@ -142,7 +155,7 @@ static inline int INET_ECN_set_ce(struct sk_buff *skb)
case cpu_to_be16(ETH_P_IPV6):
if (skb_network_header(skb) + sizeof(struct ipv6hdr) <=
skb_tail_pointer(skb))
return IP6_ECN_set_ce(ipv6_hdr(skb));
return IP6_ECN_set_ce(skb, ipv6_hdr(skb));
break;
}

2
net/ipv6/xfrm6_mode_tunnel.c
View File

@ -23,7 +23,7 @@ static inline void ipip6_ecn_decapsulate(struct sk_buff *skb)
struct ipv6hdr *inner_iph = ipipv6_hdr(skb);
if (INET_ECN_is_ce(XFRM_MODE_SKB_CB(skb)->tos))
IP6_ECN_set_ce(inner_iph);
IP6_ECN_set_ce(skb, inner_iph);
}
/* Add encapsulation header.