[NETFILTER]: Fix UDP checksum in ip_nat_mangle_udp_packet, remove skb->csum hacks

diff --git a/net/ipv4/netfilter/ip_nat_helper.c b/net/ipv4/netfilter/ip_nat_helper.c
index 4abd1f64f99eb642d46bf5f12c162b650bf573bc..74541f798668dada102560de3d7fa6ca253f7b25 100644 (file)
--- a/net/ipv4/netfilter/ip_nat_helper.c
+++ b/net/ipv4/netfilter/ip_nat_helper.c
@@ -122,7 +122,6 @@ static void mangle_contents(struct sk_buff *skb,
        /* fix IP hdr checksum information */
        skb->nh.iph->tot_len = htons(skb->len);
        ip_send_check(skb->nh.iph);
-       skb->csum = csum_partial(data, skb->len - dataoff, 0);
 }
 
 /* Unusual, but possible case. */
@@ -167,6 +166,7 @@ ip_nat_mangle_tcp_packet(struct sk_buff **pskb,
 {
        struct iphdr *iph;
        struct tcphdr *tcph;
+       int datalen;
 
        if (!skb_ip_make_writable(pskb, (*pskb)->len))
                return 0;
@@ -184,11 +184,11 @@ ip_nat_mangle_tcp_packet(struct sk_buff **pskb,
        mangle_contents(*pskb, iph->ihl*4 + tcph->doff*4,
                        match_offset, match_len, rep_buffer, rep_len);
 
+       datalen = (*pskb)->len - iph->ihl*4;
        tcph->check = 0;
-       tcph->check = tcp_v4_check(tcph, (*pskb)->len - iph->ihl*4,
-                                  iph->saddr, iph->daddr,
-                                  csum_partial((char *)tcph, tcph->doff*4,
-                                               (*pskb)->csum));
+       tcph->check = tcp_v4_check(tcph, datalen, iph->saddr, iph->daddr,
+                                  csum_partial((char *)tcph, datalen, 0));
+
        adjust_tcp_sequence(ntohl(tcph->seq),
                            (int)rep_len - (int)match_len,
                            ct, ctinfo);
@@ -216,7 +216,6 @@ ip_nat_mangle_udp_packet(struct sk_buff **pskb,
 {
        struct iphdr *iph;
        struct udphdr *udph;
-       int need_csum = ((*pskb)->csum != 0);
 
        if (!skb_ip_make_writable(pskb, (*pskb)->len))
                return 0;
@@ -235,17 +234,15 @@ ip_nat_mangle_udp_packet(struct sk_buff **pskb,
        udph->len = htons((*pskb)->len - iph->ihl*4);
 
        /* fix udp checksum if udp checksum was previously calculated */
-       if (need_csum) {
+       if (udph->check) {
+               int datalen = (*pskb)->len - iph->ihl * 4;
                udph->check = 0;
-               udph->check
-                       = csum_tcpudp_magic(iph->saddr, iph->daddr,
-                                           (*pskb)->len - iph->ihl*4,
-                                           IPPROTO_UDP,
-                                           csum_partial((char *)udph,
-                                                        sizeof(struct udphdr),
-                                                        (*pskb)->csum));
-       } else
-               (*pskb)->csum = 0;
+               udph->check = csum_tcpudp_magic(iph->saddr, iph->daddr,
+                                               datalen, IPPROTO_UDP,
+                                               csum_partial((char *)udph,
+                                                            datalen, 0));
+       }
+
        return 1;
 }