When modifying IP addresses or ports on a UDP packet we don't
correctly follow the rules for unchecksummed packets.  This meant
that packets without a checksum can be given a incorrect new checksum
and packets with a checksum can become marked as being unchecksummed.
This fixes it to handle those requirements.

Bug #8937

Signed-off-by: Jesse Gross <je...@nicira.com>
---
 datapath/actions.c |   38 ++++++++++++++++++++++++++++++--------
 1 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/datapath/actions.c b/datapath/actions.c
index 4b07603..6f6b82d 100644
--- a/datapath/actions.c
+++ b/datapath/actions.c
@@ -147,9 +147,17 @@ static void set_ip_addr(struct sk_buff *skb, struct iphdr 
*nh,
                        inet_proto_csum_replace4(&tcp_hdr(skb)->check, skb,
                                                 *addr, new_addr, 1);
        } else if (nh->protocol == IPPROTO_UDP) {
-               if (likely(transport_len >= sizeof(struct udphdr)))
-                       inet_proto_csum_replace4(&udp_hdr(skb)->check, skb,
-                                                *addr, new_addr, 1);
+               if (likely(transport_len >= sizeof(struct udphdr))) {
+                       struct udphdr *uh = udp_hdr(skb);
+
+                       if (uh->check ||
+                           get_ip_summed(skb) == OVS_CSUM_PARTIAL) {
+                               inet_proto_csum_replace4(&uh->check, skb,
+                                                        *addr, new_addr, 1);
+                               if (!uh->check)
+                                       uh->check = CSUM_MANGLED_0;
+                       }
+               }
        }
 
        csum_replace4(&nh->check, *addr, new_addr);
@@ -199,8 +207,22 @@ static void set_tp_port(struct sk_buff *skb, __be16 *port,
        skb_clear_rxhash(skb);
 }
 
-static int set_udp_port(struct sk_buff *skb,
-                       const struct ovs_key_udp *udp_port_key)
+static void set_udp_port(struct sk_buff *skb, __be16 *port, __be16 new_port)
+{
+        struct udphdr *uh = udp_hdr(skb);
+
+       if (uh->check && get_ip_summed(skb) != OVS_CSUM_PARTIAL) {
+               set_tp_port(skb, port, new_port, &uh->check);
+
+                if (!uh->check)
+                        uh->check = CSUM_MANGLED_0;
+       } else {
+               *port = new_port;
+               skb_clear_rxhash(skb);
+       }
+}
+
+static int set_udp(struct sk_buff *skb, const struct ovs_key_udp *udp_port_key)
 {
        struct udphdr *uh;
        int err;
@@ -212,10 +234,10 @@ static int set_udp_port(struct sk_buff *skb,
 
        uh = udp_hdr(skb);
        if (udp_port_key->udp_src != uh->source)
-               set_tp_port(skb, &uh->source, udp_port_key->udp_src, 
&uh->check);
+               set_udp_port(skb, &uh->source, udp_port_key->udp_src);
 
        if (udp_port_key->udp_dst != uh->dest)
-               set_tp_port(skb, &uh->dest, udp_port_key->udp_dst, &uh->check);
+               set_udp_port(skb, &uh->dest, udp_port_key->udp_dst);
 
        return 0;
 }
@@ -338,7 +360,7 @@ static int execute_set_action(struct sk_buff *skb,
                break;
 
        case OVS_KEY_ATTR_UDP:
-               err = set_udp_port(skb, nla_data(nested_attr));
+               err = set_udp(skb, nla_data(nested_attr));
                break;
        }
 
-- 
1.7.5.4

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