Messages in this thread Patch in this message | | | From | Praveen Chaudhary <> | Subject | [PATCH] [netfilter]: Fix skb->csum calculation when netfilter manipulation for NF_NAT_MANIP_SRC\DST is done on IPV6 packet. | Date | Mon, 28 Oct 2019 15:27:55 -0700 |
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No need to update skb->csum in function inet_proto_csum_replace16(), even if skb->ip_summed == CHECKSUM_COMPLETE, because change in L4 header checksum field and change in IPV6 header cancels each other for skb->csum calculation.
Signed-off-by: Praveen Chaudhary <pchaudhary@linkedin.com> Signed-off-by: Zhenggen Xu <zxu@linkedin.com> Signed-off-by: Andy Stracner <astracner@linkedin.com> --- Changes in V2. 1.) Updating diff as per email discussion with Florian Westphal. Since inet_proto_csum_replace16() does incorrect calculation for skb->csum in all cases. 2.) Change in Commmit logs. --- --- net/core/utils.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/net/core/utils.c b/net/core/utils.c index 6b6e51d..cec9924 100644 --- a/net/core/utils.c +++ b/net/core/utils.c @@ -438,6 +438,12 @@ void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb, } EXPORT_SYMBOL(inet_proto_csum_replace4); +/** + * No need to update skb->csum in this function, even if + * skb->ip_summed == CHECKSUM_COMPLETE, because change in + * L4 header checksum field and change in IPV6 header + * cancels each other for skb->csum calculation. + */ void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb, const __be32 *from, const __be32 *to, bool pseudohdr) @@ -449,9 +455,6 @@ 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))); -- 2.7.4
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