From: Praveen Chaudhary praveen5582@gmail.com
[ Upstream commit 189c9b1e94539b11c80636bc13e9cf47529e7bba ]
skb->csum is updated incorrectly, when manipulation for NF_NAT_MANIP_SRC\DST is done on IPV6 packet.
Fix: There is no need to update skb->csum in inet_proto_csum_replace16(), because update in two fields a.) IPv6 src/dst address and b.) L4 header checksum cancels each other for skb->csum calculation. Whereas inet_proto_csum_replace4 function needs to update skb->csum, because update in 3 fields a.) IPv4 src/dst address, b.) IPv4 Header checksum and c.) L4 header checksum results in same diff as L4 Header checksum for skb->csum calculation.
[ pablo@netfilter.org: a few comestic documentation edits ] Signed-off-by: Praveen Chaudhary pchaudhary@linkedin.com Signed-off-by: Zhenggen Xu zxu@linkedin.com Signed-off-by: Andy Stracner astracner@linkedin.com Reviewed-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/utils.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-)
diff --git a/net/core/utils.c b/net/core/utils.c index 2a597ac7808e2..60045e9fea05b 100644 --- a/net/core/utils.c +++ b/net/core/utils.c @@ -442,6 +442,23 @@ void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb, } EXPORT_SYMBOL(inet_proto_csum_replace4);
+/** + * inet_proto_csum_replace16 - update layer 4 header checksum field + * @sum: Layer 4 header checksum field + * @skb: sk_buff for the packet + * @from: old IPv6 address + * @to: new IPv6 address + * @pseudohdr: True if layer 4 header checksum includes pseudoheader + * + * Update layer 4 header as per the update in IPv6 src/dst address. + * + * There is no need to update skb->csum in this function, because update in two + * fields a.) IPv6 src/dst address and b.) L4 header checksum cancels each other + * for skb->csum calculation. Whereas inet_proto_csum_replace4 function needs to + * update skb->csum, because update in 3 fields a.) IPv4 src/dst address, + * b.) IPv4 Header checksum and c.) L4 header checksum results in same diff as + * L4 Header checksum for skb->csum calculation. + */ void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb, const __be32 *from, const __be32 *to, bool pseudohdr) @@ -453,9 +470,6 @@ void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb, if (skb->ip_summed != CHECKSUM_PARTIAL) { *sum = csum_fold(csum_partial(diff, sizeof(diff), ~csum_unfold(*sum))); - if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr) - skb->csum = ~csum_partial(diff, sizeof(diff), - ~skb->csum); } else if (pseudohdr) *sum = ~csum_fold(csum_partial(diff, sizeof(diff), csum_unfold(*sum)));