[PATCH 3.12 074/175] pktgen: fix UDP checksum computation

[Jiri Slaby]

From: Sabrina Dubroca <s...@queasysnail.net>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

[ Upstream commit 7744b5f3693cc06695cb9d6667671c790282730f ]

This patch fixes two issues in UDP checksum computation in pktgen.

First, the pseudo-header uses the source and destination IP
addresses. Currently, the ports are used for IPv4.

Second, the UDP checksum covers both header and data.  So we need to
generate the data earlier (move pktgen_finalize_skb up), and compute
the checksum for UDP header + data.

Fixes: c26bf4a51308c ("pktgen: Add UDPCSUM flag to support UDP checksums")
Signed-off-by: Sabrina Dubroca <s...@queasysnail.net>
Acked-by: Thomas Graf <tg...@suug.ch>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Jiri Slaby <jsl...@suse.cz>
---
 net/core/pktgen.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index a797fff7f222..a104ba3c5768 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -2771,25 +2771,25 @@ static struct sk_buff *fill_packet_ipv4(struct 
net_device *odev,
        skb->dev = odev;
        skb->pkt_type = PACKET_HOST;
 
+       pktgen_finalize_skb(pkt_dev, skb, datalen);
+
        if (!(pkt_dev->flags & F_UDPCSUM)) {
                skb->ip_summed = CHECKSUM_NONE;
        } else if (odev->features & NETIF_F_V4_CSUM) {
                skb->ip_summed = CHECKSUM_PARTIAL;
                skb->csum = 0;
-               udp4_hwcsum(skb, udph->source, udph->dest);
+               udp4_hwcsum(skb, iph->saddr, iph->daddr);
        } else {
-               __wsum csum = udp_csum(skb);
+               __wsum csum = skb_checksum(skb, skb_transport_offset(skb), 
datalen + 8, 0);
 
                /* add protocol-dependent pseudo-header */
-               udph->check = csum_tcpudp_magic(udph->source, udph->dest,
+               udph->check = csum_tcpudp_magic(iph->saddr, iph->daddr,
                                                datalen + 8, IPPROTO_UDP, csum);
 
                if (udph->check == 0)
                        udph->check = CSUM_MANGLED_0;
        }
 
-       pktgen_finalize_skb(pkt_dev, skb, datalen);
-
 #ifdef CONFIG_XFRM
        if (!process_ipsec(pkt_dev, skb, protocol))
                return NULL;
@@ -2905,6 +2905,8 @@ static struct sk_buff *fill_packet_ipv6(struct net_device 
*odev,
        skb->dev = odev;
        skb->pkt_type = PACKET_HOST;
 
+       pktgen_finalize_skb(pkt_dev, skb, datalen);
+
        if (!(pkt_dev->flags & F_UDPCSUM)) {
                skb->ip_summed = CHECKSUM_NONE;
        } else if (odev->features & NETIF_F_V6_CSUM) {
@@ -2913,7 +2915,7 @@ static struct sk_buff *fill_packet_ipv6(struct net_device 
*odev,
                skb->csum_offset = offsetof(struct udphdr, check);
                udph->check = ~csum_ipv6_magic(&iph->saddr, &iph->daddr, 
udplen, IPPROTO_UDP, 0);
        } else {
-               __wsum csum = udp_csum(skb);
+               __wsum csum = skb_checksum(skb, skb_transport_offset(skb), 
udplen, 0);
 
                /* add protocol-dependent pseudo-header */
                udph->check = csum_ipv6_magic(&iph->saddr, &iph->daddr, udplen, 
IPPROTO_UDP, csum);
@@ -2922,8 +2924,6 @@ static struct sk_buff *fill_packet_ipv6(struct net_device 
*odev,
                        udph->check = CSUM_MANGLED_0;
        }
 
-       pktgen_finalize_skb(pkt_dev, skb, datalen);
-
        return skb;
 }
 
-- 
2.3.0

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