[2/4] net/tap: fix Rx cksum flags on TCP packets
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Commit Message
Since commit d5df2ae0428a ("net: fix unneeded replacement of TCP
checksum 0"), the functions rte_ipv4_udptcp_cksum() or
rte_ipv6_udptcp_cksum() can return either 0x0000 or 0xffff when used to
verify a packet containing a valid checksum.
This new behavior broke the checksum verification in tap driver for TCP
packets: these packets are marked with PKT_RX_L4_CKSUM_BAD.
Fix this by checking the 2 possible values. A next commit will introduce
a checksum verification helper to simplify this a bit.
Fixes: d5df2ae0428a ("net: fix unneeded replacement of TCP checksum 0")
Cc: stable@dpdk.org
Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
---
drivers/net/tap/rte_eth_tap.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
Comments
On 4/27/21 4:57 PM, Olivier Matz wrote:
> Since commit d5df2ae0428a ("net: fix unneeded replacement of TCP
> checksum 0"), the functions rte_ipv4_udptcp_cksum() or
> rte_ipv6_udptcp_cksum() can return either 0x0000 or 0xffff when used to
> verify a packet containing a valid checksum.
>
> This new behavior broke the checksum verification in tap driver for TCP
> packets: these packets are marked with PKT_RX_L4_CKSUM_BAD.
>
> Fix this by checking the 2 possible values. A next commit will introduce
> a checksum verification helper to simplify this a bit.
>
> Fixes: d5df2ae0428a ("net: fix unneeded replacement of TCP checksum 0")
> Cc: stable@dpdk.org
>
> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Acked-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
@@ -346,6 +346,8 @@ tap_verify_csum(struct rte_mbuf *mbuf)
return;
}
if (l4 == RTE_PTYPE_L4_UDP || l4 == RTE_PTYPE_L4_TCP) {
+ int cksum_ok;
+
l4_hdr = rte_pktmbuf_mtod_offset(mbuf, void *, l2_len + l3_len);
/* Don't verify checksum for multi-segment packets. */
if (mbuf->nb_segs > 1)
@@ -363,13 +365,13 @@ tap_verify_csum(struct rte_mbuf *mbuf)
return;
}
}
- cksum = ~rte_ipv4_udptcp_cksum(l3_hdr, l4_hdr);
+ cksum = rte_ipv4_udptcp_cksum(l3_hdr, l4_hdr);
} else { /* l3 == RTE_PTYPE_L3_IPV6, checked above */
- cksum = ~rte_ipv6_udptcp_cksum(l3_hdr, l4_hdr);
+ cksum = rte_ipv6_udptcp_cksum(l3_hdr, l4_hdr);
}
- mbuf->ol_flags |= cksum ?
- PKT_RX_L4_CKSUM_BAD :
- PKT_RX_L4_CKSUM_GOOD;
+ cksum_ok = (cksum == 0) || (cksum == 0xffff);
+ mbuf->ol_flags |= cksum_ok ?
+ PKT_RX_L4_CKSUM_GOOD : PKT_RX_L4_CKSUM_BAD;
}
}