| /* (C) 1999-2001 Paul `Rusty' Russell |
| * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| */ |
| |
| #include <linux/module.h> |
| #include <net/ipv6.h> |
| #include <net/ip6_route.h> |
| #include <net/ip6_fib.h> |
| #include <net/ip6_checksum.h> |
| #include <net/netfilter/ipv6/nf_reject.h> |
| #include <linux/netfilter_ipv6.h> |
| #include <linux/netfilter_bridge.h> |
| |
| const struct tcphdr *nf_reject_ip6_tcphdr_get(struct sk_buff *oldskb, |
| struct tcphdr *otcph, |
| unsigned int *otcplen, int hook) |
| { |
| const struct ipv6hdr *oip6h = ipv6_hdr(oldskb); |
| u8 proto; |
| __be16 frag_off; |
| int tcphoff; |
| |
| proto = oip6h->nexthdr; |
| tcphoff = ipv6_skip_exthdr(oldskb, ((u8 *)(oip6h + 1) - oldskb->data), |
| &proto, &frag_off); |
| |
| if ((tcphoff < 0) || (tcphoff > oldskb->len)) { |
| pr_debug("Cannot get TCP header.\n"); |
| return NULL; |
| } |
| |
| *otcplen = oldskb->len - tcphoff; |
| |
| /* IP header checks: fragment, too short. */ |
| if (proto != IPPROTO_TCP || *otcplen < sizeof(struct tcphdr)) { |
| pr_debug("proto(%d) != IPPROTO_TCP or too short (len = %d)\n", |
| proto, *otcplen); |
| return NULL; |
| } |
| |
| otcph = skb_header_pointer(oldskb, tcphoff, sizeof(struct tcphdr), |
| otcph); |
| if (otcph == NULL) |
| return NULL; |
| |
| /* No RST for RST. */ |
| if (otcph->rst) { |
| pr_debug("RST is set\n"); |
| return NULL; |
| } |
| |
| /* Check checksum. */ |
| if (nf_ip6_checksum(oldskb, hook, tcphoff, IPPROTO_TCP)) { |
| pr_debug("TCP checksum is invalid\n"); |
| return NULL; |
| } |
| |
| return otcph; |
| } |
| EXPORT_SYMBOL_GPL(nf_reject_ip6_tcphdr_get); |
| |
| struct ipv6hdr *nf_reject_ip6hdr_put(struct sk_buff *nskb, |
| const struct sk_buff *oldskb, |
| __u8 protocol, int hoplimit) |
| { |
| struct ipv6hdr *ip6h; |
| const struct ipv6hdr *oip6h = ipv6_hdr(oldskb); |
| #define DEFAULT_TOS_VALUE 0x0U |
| const __u8 tclass = DEFAULT_TOS_VALUE; |
| |
| skb_put(nskb, sizeof(struct ipv6hdr)); |
| skb_reset_network_header(nskb); |
| ip6h = ipv6_hdr(nskb); |
| ip6_flow_hdr(ip6h, tclass, 0); |
| ip6h->hop_limit = hoplimit; |
| ip6h->nexthdr = protocol; |
| ip6h->saddr = oip6h->daddr; |
| ip6h->daddr = oip6h->saddr; |
| |
| nskb->protocol = htons(ETH_P_IPV6); |
| |
| return ip6h; |
| } |
| EXPORT_SYMBOL_GPL(nf_reject_ip6hdr_put); |
| |
| void nf_reject_ip6_tcphdr_put(struct sk_buff *nskb, |
| const struct sk_buff *oldskb, |
| const struct tcphdr *oth, unsigned int otcplen) |
| { |
| struct tcphdr *tcph; |
| int needs_ack; |
| |
| skb_reset_transport_header(nskb); |
| tcph = skb_put(nskb, sizeof(struct tcphdr)); |
| /* Truncate to length (no data) */ |
| tcph->doff = sizeof(struct tcphdr)/4; |
| tcph->source = oth->dest; |
| tcph->dest = oth->source; |
| |
| if (oth->ack) { |
| needs_ack = 0; |
| tcph->seq = oth->ack_seq; |
| tcph->ack_seq = 0; |
| } else { |
| needs_ack = 1; |
| tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn + oth->fin + |
| otcplen - (oth->doff<<2)); |
| tcph->seq = 0; |
| } |
| |
| /* Reset flags */ |
| ((u_int8_t *)tcph)[13] = 0; |
| tcph->rst = 1; |
| tcph->ack = needs_ack; |
| tcph->window = 0; |
| tcph->urg_ptr = 0; |
| tcph->check = 0; |
| |
| /* Adjust TCP checksum */ |
| tcph->check = csum_ipv6_magic(&ipv6_hdr(nskb)->saddr, |
| &ipv6_hdr(nskb)->daddr, |
| sizeof(struct tcphdr), IPPROTO_TCP, |
| csum_partial(tcph, |
| sizeof(struct tcphdr), 0)); |
| } |
| EXPORT_SYMBOL_GPL(nf_reject_ip6_tcphdr_put); |
| |
| void nf_send_reset6(struct net *net, struct sk_buff *oldskb, int hook) |
| { |
| struct sk_buff *nskb; |
| struct tcphdr _otcph; |
| const struct tcphdr *otcph; |
| unsigned int otcplen, hh_len; |
| const struct ipv6hdr *oip6h = ipv6_hdr(oldskb); |
| struct ipv6hdr *ip6h; |
| struct dst_entry *dst = NULL; |
| struct flowi6 fl6; |
| |
| if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) || |
| (!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) { |
| pr_debug("addr is not unicast.\n"); |
| return; |
| } |
| |
| otcph = nf_reject_ip6_tcphdr_get(oldskb, &_otcph, &otcplen, hook); |
| if (!otcph) |
| return; |
| |
| memset(&fl6, 0, sizeof(fl6)); |
| fl6.flowi6_proto = IPPROTO_TCP; |
| fl6.saddr = oip6h->daddr; |
| fl6.daddr = oip6h->saddr; |
| fl6.fl6_sport = otcph->dest; |
| fl6.fl6_dport = otcph->source; |
| fl6.flowi6_oif = l3mdev_master_ifindex(skb_dst(oldskb)->dev); |
| fl6.flowi6_mark = IP6_REPLY_MARK(net, oldskb->mark); |
| security_skb_classify_flow(oldskb, flowi6_to_flowi(&fl6)); |
| dst = ip6_route_output(net, NULL, &fl6); |
| if (dst->error) { |
| dst_release(dst); |
| return; |
| } |
| dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0); |
| if (IS_ERR(dst)) |
| return; |
| |
| hh_len = (dst->dev->hard_header_len + 15)&~15; |
| nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr) |
| + sizeof(struct tcphdr) + dst->trailer_len, |
| GFP_ATOMIC); |
| |
| if (!nskb) { |
| net_dbg_ratelimited("cannot alloc skb\n"); |
| dst_release(dst); |
| return; |
| } |
| |
| skb_dst_set(nskb, dst); |
| |
| nskb->mark = fl6.flowi6_mark; |
| |
| skb_reserve(nskb, hh_len + dst->header_len); |
| ip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_TCP, |
| ip6_dst_hoplimit(dst)); |
| nf_reject_ip6_tcphdr_put(nskb, oldskb, otcph, otcplen); |
| |
| nf_ct_attach(nskb, oldskb); |
| |
| #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) |
| /* If we use ip6_local_out for bridged traffic, the MAC source on |
| * the RST will be ours, instead of the destination's. This confuses |
| * some routers/firewalls, and they drop the packet. So we need to |
| * build the eth header using the original destination's MAC as the |
| * source, and send the RST packet directly. |
| */ |
| if (oldskb->nf_bridge) { |
| struct ethhdr *oeth = eth_hdr(oldskb); |
| |
| nskb->dev = nf_bridge_get_physindev(oldskb); |
| nskb->protocol = htons(ETH_P_IPV6); |
| ip6h->payload_len = htons(sizeof(struct tcphdr)); |
| if (dev_hard_header(nskb, nskb->dev, ntohs(nskb->protocol), |
| oeth->h_source, oeth->h_dest, nskb->len) < 0) |
| return; |
| dev_queue_xmit(nskb); |
| } else |
| #endif |
| ip6_local_out(net, nskb->sk, nskb); |
| } |
| EXPORT_SYMBOL_GPL(nf_send_reset6); |
| |
| static bool reject6_csum_ok(struct sk_buff *skb, int hook) |
| { |
| const struct ipv6hdr *ip6h = ipv6_hdr(skb); |
| int thoff; |
| __be16 fo; |
| u8 proto; |
| |
| if (skb_csum_unnecessary(skb)) |
| return true; |
| |
| proto = ip6h->nexthdr; |
| thoff = ipv6_skip_exthdr(skb, ((u8 *)(ip6h + 1) - skb->data), &proto, &fo); |
| |
| if (thoff < 0 || thoff >= skb->len || (fo & htons(~0x7)) != 0) |
| return false; |
| |
| return nf_ip6_checksum(skb, hook, thoff, proto) == 0; |
| } |
| |
| void nf_send_unreach6(struct net *net, struct sk_buff *skb_in, |
| unsigned char code, unsigned int hooknum) |
| { |
| if (!reject6_csum_ok(skb_in, hooknum)) |
| return; |
| |
| if (hooknum == NF_INET_LOCAL_OUT && skb_in->dev == NULL) |
| skb_in->dev = net->loopback_dev; |
| |
| icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0); |
| } |
| EXPORT_SYMBOL_GPL(nf_send_unreach6); |
| |
| MODULE_LICENSE("GPL"); |