From: Ben Pfaff Date: Wed, 12 Nov 2008 22:42:51 +0000 (-0800) Subject: Pull data into headers properly, and checksum ICMP replies correctly. X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7d5bd14ebd213a6625dc1a3ddd18d8e75ca8a979;p=openvswitch Pull data into headers properly, and checksum ICMP replies correctly. --- diff --git a/datapath/nx_act_snat.c b/datapath/nx_act_snat.c index e577c9d4..2d0306ad 100644 --- a/datapath/nx_act_snat.c +++ b/datapath/nx_act_snat.c @@ -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); + 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); - 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 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);