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net: qualcomm: rmnet: IPv6 payload length is simple
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We don't support any extension headers for IPv6 packets.  Extension
headers therefore contribute 0 bytes to the payload length.  As a
result we can just use the IPv6 payload length as the length used to
compute the pseudo header checksum for both UDP and TCP messages.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Alex Elder authored and David S. Miller committed Jun 12, 2021
1 parent 411a795 commit 185a108
Showing 1 changed file with 2 additions and 5 deletions.
7 changes: 2 additions & 5 deletions drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
Original file line number Diff line number Diff line change
Expand Up @@ -114,7 +114,6 @@ rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb,
__sum16 *csum_field, pseudo_csum;
__sum16 ip6_payload_csum;
__be16 ip_header_csum;
u32 length;

/* Checksum offload is only supported for UDP and TCP protocols;
* the packet cannot include any IPv6 extension headers
Expand All @@ -134,11 +133,9 @@ rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb,
ip_header_csum = (__force __be16)ip_fast_csum(ip6h, sizeof(*ip6h) / 4);
ip6_payload_csum = csum16_sub(csum_trailer->csum_value, ip_header_csum);

length = (ip6h->nexthdr == IPPROTO_UDP) ?
ntohs(((struct udphdr *)txporthdr)->len) :
ntohs(ip6h->payload_len);
pseudo_csum = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
length, ip6h->nexthdr, 0);
ntohs(ip6h->payload_len),
ip6h->nexthdr, 0);

/* It's sufficient to compare the IP payload checksum with the
* negated pseudo checksum to determine whether the packet
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