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esp6: Fix RX checksum after header pull
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Both ip6_input_finish (non-GRO) and esp6_gro_receive (GRO) strip
the IPv6 header without adjusting skb->csum accordingly. As a
result CHECKSUM_COMPLETE breaks and "hw csum failure" is written
to the kernel log by netdev_rx_csum_fault (dev.c).

Fix skb->csum by substracting the checksum value of the pulled IPv6
header using a call to skb_postpull_rcsum.

This affects both transport and tunnel modes.

Note that the fix occurs far from the place that the header was
pulled. This is based on existing code, see:
ipv6_srh_rcv() in exthdrs.c and rawv6_rcv() in raw.c

Signed-off-by: Yossi Kuperman <yossiku@mellanox.com>
Signed-off-by: Ilan Tayari <ilant@mellanox.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
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Yossi Kuperman authored and Steffen Klassert committed Aug 2, 2017
1 parent e9cba69 commit a9b28c2
Showing 1 changed file with 2 additions and 0 deletions.
2 changes: 2 additions & 0 deletions net/ipv6/esp6.c
Original file line number Diff line number Diff line change
Expand Up @@ -495,6 +495,8 @@ int esp6_input_done2(struct sk_buff *skb, int err)

trimlen = alen + padlen + 2;
if (skb->ip_summed == CHECKSUM_COMPLETE) {
skb_postpull_rcsum(skb, skb_network_header(skb),
skb_network_header_len(skb));
csumdiff = skb_checksum(skb, skb->len - trimlen, trimlen, 0);
skb->csum = csum_block_sub(skb->csum, csumdiff,
skb->len - trimlen);
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