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Pull data into headers properly, and checksum ICMP replies correctly.

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This commit is contained in:
Ben Pfaff committed 2008-11-13 12:45:38 -08:00
1 parent b4181aef87
commit 7d5bd14ebd
1 file changed
+31 -16
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datapath/nx_act_snat.c
+31 -16
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@@ -235,29 +235,28 @@ handle_icmp_snat(struct sk_buff *skb)
{
struct net_bridge_port *p = skb->dev->br_port;
struct ethhdr *eh;
struct iphdr *iph = ip_hdr(skb);
struct iphdr *iph;
struct icmphdr *icmph;
unsigned int datalen;
uint8_t tmp_eth[ETH_ALEN];
uint32_t tmp_ip;
struct sk_buff *nskb;
/* We're only interested in addresses we rewrite. */
iph = ip_hdr(skb);
if (!snat_this_address(p, iph->daddr)) {
return 0;
}
icmph = (struct icmphdr *) ((u_int32_t *)iph + iph->ihl);
datalen = skb->len - iph->ihl * 4;
/* Drop fragments and packets not long enough to hold the ICMP
* header. */
if (((ntohs(iph->frag_off) & IP_OFFSET) != 0) || datalen < 4)
if ((ntohs(iph->frag_off) & IP_OFFSET) != 0 ||
!pskb_may_pull(skb, skb_transport_offset(skb) + 4))
return 0;
/* We only respond to echo requests to our address. Continue
* processing replies and other ICMP messages since they may be
* intended for NAT'd hosts. */
icmph = icmp_hdr(skb);
if (icmph->type != ICMP_ECHO)
return 0;
@@ -269,19 +268,31 @@ handle_icmp_snat(struct sk_buff *skb)
return -1;
}
/* Update Ethernet header. */
eh = eth_hdr(nskb);
iph = ip_hdr(nskb);
icmph = (struct icmphdr *) ((u_int32_t *)iph + iph->ihl);
tmp_ip = iph->daddr;
iph->daddr = iph->saddr;
iph->saddr = tmp_ip;
memcpy(tmp_eth, eh->h_dest, ETH_ALEN);
memcpy(eh->h_dest, eh->h_source, ETH_ALEN);
memcpy(eh->h_source, tmp_eth, ETH_ALEN);
/* Update IP header.
* This is kind of busted, at least in that it doesn't check that the
* echoed IP options make sense. */
iph = ip_hdr(nskb);
iph->id = 0;
iph->frag_off = 0;
iph->ttl = IPDEFTTL;
iph->check = 0;
tmp_ip = iph->daddr;
iph->daddr = iph->saddr;
iph->saddr = tmp_ip;
iph->check = ip_fast_csum(iph, iph->ihl);
/* Update ICMP header. */
icmph = icmp_hdr(nskb);
icmph->type = ICMP_ECHOREPLY;
icmph->checksum = 0;
icmph->checksum = ip_compute_csum(icmph,
nskb->tail - nskb->transport_header);
dp_xmit_skb_push(nskb);
@@ -303,6 +314,7 @@ snat_pre_route(struct sk_buff *skb)
struct iphdr *iph;
int len;
WARN_ON_ONCE(skb_network_offset(skb));
if (skb->protocol == htons(ETH_P_ARP))
return handle_arp_snat(skb);
else if (skb->protocol != htons(ETH_P_IP))
@@ -315,14 +327,17 @@ snat_pre_route(struct sk_buff *skb)
if (iph->ihl < 5 || iph->version != 4)
goto ipv4_error;
if (!pskb_may_pull(skb, iph->ihl*4))
if (!pskb_may_pull(skb, ip_hdrlen(skb)))
goto ipv4_error;
skb_set_transport_header(skb, ip_hdrlen(skb));
/* Check if we need to echo reply for this address */
iph = ip_hdr(skb);
if ((iph->protocol == IPPROTO_ICMP) && (handle_icmp_snat(skb)))
return -1;
if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
iph = ip_hdr(skb);
if (unlikely(ip_fast_csum(iph, iph->ihl)))
goto ipv4_error;
len = ntohs(iph->tot_len);