diff options
| -rw-r--r-- | net/ipv4/netfilter/ipt_REJECT.c | 102 |
1 files changed, 37 insertions, 65 deletions
diff --git a/net/ipv4/netfilter/ipt_REJECT.c b/net/ipv4/netfilter/ipt_REJECT.c index e3c2ecc341e..22606e2baa1 100644 --- a/net/ipv4/netfilter/ipt_REJECT.c +++ b/net/ipv4/netfilter/ipt_REJECT.c @@ -35,11 +35,8 @@ MODULE_DESCRIPTION("Xtables: packet \"rejection\" target for IPv4"); static void send_reset(struct sk_buff *oldskb, int hook) { struct sk_buff *nskb; - struct iphdr *niph; + struct iphdr *oiph, *niph; struct tcphdr _otcph, *oth, *tcph; - __be16 tmp_port; - __be32 tmp_addr; - int needs_ack; unsigned int addr_type; /* IP header checks: fragment. */ @@ -58,69 +55,47 @@ static void send_reset(struct sk_buff *oldskb, int hook) /* Check checksum */ if (nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), IPPROTO_TCP)) return; + oiph = ip_hdr(oldskb); - /* We need a linear, writeable skb. We also need to expand - headroom in case hh_len of incoming interface < hh_len of - outgoing interface */ - nskb = skb_copy_expand(oldskb, LL_MAX_HEADER, skb_tailroom(oldskb), - GFP_ATOMIC); + nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) + + LL_MAX_HEADER, GFP_ATOMIC); if (!nskb) return; - /* This packet will not be the same as the other: clear nf fields */ - nf_reset(nskb); - nskb->mark = 0; - skb_init_secmark(nskb); - - skb_shinfo(nskb)->gso_size = 0; - skb_shinfo(nskb)->gso_segs = 0; - skb_shinfo(nskb)->gso_type = 0; - - tcph = (struct tcphdr *)(skb_network_header(nskb) + ip_hdrlen(nskb)); - - /* Swap source and dest */ - niph = ip_hdr(nskb); - tmp_addr = niph->saddr; - niph->saddr = niph->daddr; - niph->daddr = tmp_addr; - tmp_port = tcph->source; - tcph->source = tcph->dest; - tcph->dest = tmp_port; - - /* Truncate to length (no data) */ - tcph->doff = sizeof(struct tcphdr)/4; - skb_trim(nskb, ip_hdrlen(nskb) + sizeof(struct tcphdr)); - - if (tcph->ack) { - needs_ack = 0; + skb_reserve(nskb, LL_MAX_HEADER); + + skb_reset_network_header(nskb); + niph = (struct iphdr *)skb_put(nskb, sizeof(struct iphdr)); + niph->version = 4; + niph->ihl = sizeof(struct iphdr) / 4; + niph->tos = 0; + niph->id = 0; + niph->frag_off = htons(IP_DF); + niph->protocol = IPPROTO_TCP; + niph->check = 0; + niph->saddr = oiph->daddr; + niph->daddr = oiph->saddr; + + tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr)); + memset(tcph, 0, sizeof(*tcph)); + tcph->source = oth->dest; + tcph->dest = oth->source; + tcph->doff = sizeof(struct tcphdr) / 4; + + if (oth->ack) tcph->seq = oth->ack_seq; - tcph->ack_seq = 0; - } else { - needs_ack = 1; + else { tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn + oth->fin + oldskb->len - ip_hdrlen(oldskb) - (oth->doff << 2)); - tcph->seq = 0; + tcph->ack = 1; } - /* Reset flags */ - ((u_int8_t *)tcph)[13] = 0; - tcph->rst = 1; - tcph->ack = needs_ack; - - tcph->window = 0; - tcph->urg_ptr = 0; - - /* Adjust TCP checksum */ - tcph->check = 0; - tcph->check = tcp_v4_check(sizeof(struct tcphdr), - niph->saddr, niph->daddr, - csum_partial(tcph, - sizeof(struct tcphdr), 0)); - - /* Set DF, id = 0 */ - niph->frag_off = htons(IP_DF); - niph->id = 0; + tcph->rst = 1; + tcph->check = tcp_v4_check(sizeof(struct tcphdr), + niph->saddr, niph->daddr, + csum_partial(tcph, + sizeof(struct tcphdr), 0)); addr_type = RTN_UNSPEC; if (hook != NF_INET_FORWARD @@ -130,14 +105,16 @@ static void send_reset(struct sk_buff *oldskb, int hook) ) addr_type = RTN_LOCAL; + /* ip_route_me_harder expects skb->dst to be set */ + dst_hold(oldskb->dst); + nskb->dst = oldskb->dst; + if (ip_route_me_harder(nskb, addr_type)) goto free_nskb; + niph->ttl = dst_metric(nskb->dst, RTAX_HOPLIMIT); nskb->ip_summed = CHECKSUM_NONE; - /* Adjust IP TTL */ - niph->ttl = dst_metric(nskb->dst, RTAX_HOPLIMIT); - /* "Never happens" */ if (nskb->len > dst_mtu(nskb->dst)) goto free_nskb; @@ -163,11 +140,6 @@ reject_tg(struct sk_buff *skb, const struct net_device *in, { const struct ipt_reject_info *reject = targinfo; - /* Our naive response construction doesn't deal with IP - options, and probably shouldn't try. */ - if (ip_hdrlen(skb) != sizeof(struct iphdr)) - return NF_DROP; - /* WARNING: This code causes reentry within iptables. This means that the iptables jump stack is now crap. We must return an absolute verdict. --RR */ |