int ip_forward(struct sk_buff *skb) { u32 mtu; struct iphdr *iph; /* Our header */ struct rtable *rt; /* Route we use */ struct ip_options *opt = &(IPCB(skb)->opt); if (skb_warn_if_lro(skb)) goto drop; if (!xfrm4_policy_check(NULL, XFRM_POLICY_FWD, skb)) goto drop; if (IPCB(skb)->opt.router_alert && ip_call_ra_chain(skb)) return NET_RX_SUCCESS; if (skb->pkt_type != PACKET_HOST) goto drop; skb_forward_csum(skb); /* * According to the RFC, we must first decrease the TTL field. If * that reaches zero, we must reply an ICMP control message telling * that the packet's lifetime expired. */ if (ip_hdr(skb)->ttl <= 1) goto too_many_hops; if (!xfrm4_route_forward(skb)) goto drop; rt = skb_rtable(skb); if (opt->is_strictroute && rt->rt_uses_gateway) goto sr_failed; IPCB(skb)->flags |= IPSKB_FORWARDED; mtu = ip_dst_mtu_maybe_forward(&rt->dst, true); if (!ip_may_fragment(skb) && ip_exceeds_mtu(skb, mtu)) { IP_INC_STATS(dev_net(rt->dst.dev), IPSTATS_MIB_FRAGFAILS); icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu)); goto drop; } /* We are about to mangle packet. Copy it! */ if (skb_cow(skb, LL_RESERVED_SPACE(rt->dst.dev)+rt->dst.header_len)) goto drop; iph = ip_hdr(skb); /* Decrease ttl after skb cow done */ ip_decrease_ttl(iph); /* * We now generate an ICMP HOST REDIRECT giving the route * we calculated. */ if (rt->rt_flags&RTCF_DOREDIRECT && !opt->srr && !skb_sec_path(skb)) ip_rt_send_redirect(skb); skb->priority = rt_tos2priority(iph->tos); return NF_HOOK(NFPROTO_IPV4, NF_INET_FORWARD, skb, skb->dev, rt->dst.dev, ip_forward_finish); sr_failed: /* * Strict routing permits no gatewaying */ icmp_send(skb, ICMP_DEST_UNREACH, ICMP_SR_FAILED, 0); goto drop; too_many_hops: /* Tell the sender its packet died... */ IP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), IPSTATS_MIB_INHDRERRORS); icmp_send(skb, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL, 0); drop: kfree_skb(skb); return NET_RX_DROP; }
int ip6_forward(struct sk_buff *skb) { struct dst_entry *dst = skb_dst(skb); struct ipv6hdr *hdr = ipv6_hdr(skb); struct inet6_skb_parm *opt = IP6CB(skb); struct net *net = dev_net(dst->dev); u32 mtu; if (net->ipv6.devconf_all->forwarding == 0) goto error; if (skb_warn_if_lro(skb)) goto drop; if (!xfrm6_policy_check(NULL, XFRM_POLICY_FWD, skb)) { IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_INDISCARDS); goto drop; } if (skb->pkt_type != PACKET_HOST) goto drop; skb_forward_csum(skb); /* * We DO NOT make any processing on * RA packets, pushing them to user level AS IS * without ane WARRANTY that application will be able * to interpret them. The reason is that we * cannot make anything clever here. * * We are not end-node, so that if packet contains * AH/ESP, we cannot make anything. * Defragmentation also would be mistake, RA packets * cannot be fragmented, because there is no warranty * that different fragments will go along one path. --ANK */ if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) { if (ip6_call_ra_chain(skb, ntohs(opt->ra))) return 0; } /* * check and decrement ttl */ if (hdr->hop_limit <= 1) { /* Force OUTPUT device used as source address */ skb->dev = dst->dev; icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT, 0); IP6_INC_STATS_BH(net, ip6_dst_idev(dst), IPSTATS_MIB_INHDRERRORS); kfree_skb(skb); return -ETIMEDOUT; } /* XXX: idev->cnf.proxy_ndp? */ if (net->ipv6.devconf_all->proxy_ndp && pneigh_lookup(&nd_tbl, net, &hdr->daddr, skb->dev, 0)) { int proxied = ip6_forward_proxy_check(skb); if (proxied > 0) return ip6_input(skb); else if (proxied < 0) { IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_INDISCARDS); goto drop; } } if (!xfrm6_route_forward(skb)) { IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_INDISCARDS); goto drop; } dst = skb_dst(skb); /* IPv6 specs say nothing about it, but it is clear that we cannot send redirects to source routed frames. We don't send redirects to frames decapsulated from IPsec. */ if (skb->dev == dst->dev && opt->srcrt == 0 && !skb_sec_path(skb)) { struct in6_addr *target = NULL; struct inet_peer *peer; struct rt6_info *rt; /* * incoming and outgoing devices are the same * send a redirect. */ rt = (struct rt6_info *) dst; if (rt->rt6i_flags & RTF_GATEWAY) target = &rt->rt6i_gateway; else target = &hdr->daddr; peer = inet_getpeer_v6(net->ipv6.peers, &rt->rt6i_dst.addr, 1); /* Limit redirects both by destination (here) and by source (inside ndisc_send_redirect) */ if (inet_peer_xrlim_allow(peer, 1*HZ)) ndisc_send_redirect(skb, target); if (peer) inet_putpeer(peer); } else { int addrtype = ipv6_addr_type(&hdr->saddr); /* This check is security critical. */ if (addrtype == IPV6_ADDR_ANY || addrtype & (IPV6_ADDR_MULTICAST | IPV6_ADDR_LOOPBACK)) goto error; if (addrtype & IPV6_ADDR_LINKLOCAL) { icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_NOT_NEIGHBOUR, 0); goto error; } } mtu = dst_mtu(dst); if (mtu < IPV6_MIN_MTU) mtu = IPV6_MIN_MTU; if ((!skb->local_df && skb->len > mtu && !skb_is_gso(skb)) || (IP6CB(skb)->frag_max_size && IP6CB(skb)->frag_max_size > mtu)) { /* Again, force OUTPUT device used as source address */ skb->dev = dst->dev; icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu); IP6_INC_STATS_BH(net, ip6_dst_idev(dst), IPSTATS_MIB_INTOOBIGERRORS); IP6_INC_STATS_BH(net, ip6_dst_idev(dst), IPSTATS_MIB_FRAGFAILS); kfree_skb(skb); return -EMSGSIZE; } if (skb_cow(skb, dst->dev->hard_header_len)) { IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTDISCARDS); goto drop; } hdr = ipv6_hdr(skb); /* Mangling hops number delayed to point after skb COW */ hdr->hop_limit--; IP6_INC_STATS_BH(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTFORWDATAGRAMS); IP6_ADD_STATS_BH(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTOCTETS, skb->len); return NF_HOOK(NFPROTO_IPV6, NF_INET_FORWARD, skb, skb->dev, dst->dev, ip6_forward_finish); error: IP6_INC_STATS_BH(net, ip6_dst_idev(dst), IPSTATS_MIB_INADDRERRORS); drop: kfree_skb(skb); return -EINVAL; }
int ip_forward(struct sk_buff *skb) { struct iphdr *iph; /* Our header */ struct rtable *rt; /* Route we use */ struct ip_options * opt = &(IPCB(skb)->opt); #ifdef CONFIG_NETFILTER_TABLE_INDEX int verdict; #endif if (skb_warn_if_lro(skb)) goto drop; if (!xfrm4_policy_check(NULL, XFRM_POLICY_FWD, skb)) goto drop; if (IPCB(skb)->opt.router_alert && ip_call_ra_chain(skb)) return NET_RX_SUCCESS; if (skb->pkt_type != PACKET_HOST) goto drop; skb_forward_csum(skb); /* * According to the RFC, we must first decrease the TTL field. If * that reaches zero, we must reply an ICMP control message telling * that the packet's lifetime expired. */ if (ip_hdr(skb)->ttl <= 1) goto too_many_hops; if (!xfrm4_route_forward(skb)) goto drop; rt = skb_rtable(skb); if (opt->is_strictroute && rt->rt_dst != rt->rt_gateway) goto sr_failed; if (unlikely(skb->len > dst_mtu(&rt->u.dst) && !skb_is_gso(skb) && (ip_hdr(skb)->frag_off & htons(IP_DF))) && !skb->local_df) { IP_INC_STATS(dev_net(rt->u.dst.dev), IPSTATS_MIB_FRAGFAILS); icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(dst_mtu(&rt->u.dst))); goto drop; } /* We are about to mangle packet. Copy it! */ if (skb_cow(skb, LL_RESERVED_SPACE(rt->u.dst.dev)+rt->u.dst.header_len)) goto drop; iph = ip_hdr(skb); #ifdef CONFIG_AS_FASTPATH /* ToS in route table is not actually that is in packet */ _route_add_hook(rt, iph->tos); #endif /* Decrease ttl after skb cow done */ ip_decrease_ttl(iph); /* * We now generate an ICMP HOST REDIRECT giving the route * we calculated. */ if (rt->rt_flags&RTCF_DOREDIRECT && !opt->srr && !skb_sec_path(skb)) ip_rt_send_redirect(skb); skb->priority = rt_tos2priority(iph->tos); #ifdef CONFIG_NETFILTER_TABLE_INDEX verdict = match_netfilter_table_index( NFPROTO_IPV4, NF_INET_FORWARD, skb, skb->dev, rt->u.dst.dev, p_netfilter_table_index); if (-1 == verdict) /* not found, go along the old path */ return NF_HOOK(NFPROTO_IPV4, NF_INET_FORWARD, skb, skb->dev, rt->u.dst.dev, ip_forward_finish); else{ if (verdict == NF_ACCEPT || verdict == NF_STOP) return ip_forward_finish(skb); else goto drop; /* We only recorded 3 kinds of results, * NF_ACCEPT, NF_STOP, NF DROP. * NF_DROP will be processed. * we don't accelorate NF_QUEUE */ } #endif /* end CONFIG_NETFILTER_TABLE_INDEX */ return NF_HOOK(NFPROTO_IPV4, NF_INET_FORWARD, skb, skb->dev, rt->u.dst.dev, ip_forward_finish); sr_failed: /* * Strict routing permits no gatewaying */ icmp_send(skb, ICMP_DEST_UNREACH, ICMP_SR_FAILED, 0); goto drop; too_many_hops: /* Tell the sender its packet died... */ IP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), IPSTATS_MIB_INHDRERRORS); icmp_send(skb, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL, 0); drop: kfree_skb(skb); return NET_RX_DROP; }
int ip6_forward(struct sk_buff *skb) { struct dst_entry *dst = skb_dst(skb); struct ipv6hdr *hdr = ipv6_hdr(skb); struct inet6_skb_parm *opt = IP6CB(skb); struct net *net = dev_net(dst->dev); if (net->ipv6.devconf_all->forwarding == 0) goto error; if (skb_warn_if_lro(skb)) goto drop; if (!xfrm6_policy_check(NULL, XFRM_POLICY_FWD, skb)) { IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_INDISCARDS); goto drop; } if (skb->pkt_type != PACKET_HOST) goto drop; skb_forward_csum(skb); /* * We DO NOT make any processing on * RA packets, pushing them to user level AS IS * without ane WARRANTY that application will be able * to interpret them. The reason is that we * cannot make anything clever here. * * We are not end-node, so that if packet contains * AH/ESP, we cannot make anything. * Defragmentation also would be mistake, RA packets * cannot be fragmented, because there is no warranty * that different fragments will go along one path. --ANK */ if (opt->ra) { u8 *ptr = skb_network_header(skb) + opt->ra; if (ip6_call_ra_chain(skb, (ptr[2]<<8) + ptr[3])) return 0; } /* * check and decrement ttl */ if (hdr->hop_limit <= 1) { /* Force OUTPUT device used as source address */ skb->dev = dst->dev; icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT, 0, skb->dev); IP6_INC_STATS_BH(net, ip6_dst_idev(dst), IPSTATS_MIB_INHDRERRORS); kfree_skb(skb); return -ETIMEDOUT; } /* XXX: idev->cnf.proxy_ndp? */ if (net->ipv6.devconf_all->proxy_ndp && pneigh_lookup(&nd_tbl, net, &hdr->daddr, skb->dev, 0)) { int proxied = ip6_forward_proxy_check(skb); if (proxied > 0) return ip6_input(skb); else if (proxied < 0) { IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_INDISCARDS); goto drop; } } if (!xfrm6_route_forward(skb)) { IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_INDISCARDS); goto drop; } dst = skb_dst(skb); /* IPv6 specs say nothing about it, but it is clear that we cannot send redirects to source routed frames. We don't send redirects to frames decapsulated from IPsec. */ if (skb->dev == dst->dev && dst->neighbour && opt->srcrt == 0 && !skb_sec_path(skb)) { struct in6_addr *target = NULL; struct rt6_info *rt; struct neighbour *n = dst->neighbour; /* * incoming and outgoing devices are the same * send a redirect. */ rt = (struct rt6_info *) dst; if ((rt->rt6i_flags & RTF_GATEWAY)) target = (struct in6_addr*)&n->primary_key; else target = &hdr->daddr; /* Limit redirects both by destination (here) and by source (inside ndisc_send_redirect) */ if (xrlim_allow(dst, 1*HZ)) ndisc_send_redirect(skb, n, target); } else { int addrtype = ipv6_addr_type(&hdr->saddr); /* This check is security critical. */ if (addrtype == IPV6_ADDR_ANY || addrtype & (IPV6_ADDR_MULTICAST | IPV6_ADDR_LOOPBACK)) goto error; if (addrtype & IPV6_ADDR_LINKLOCAL) { icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_NOT_NEIGHBOUR, 0, skb->dev); goto error; } } if (skb->len > dst_mtu(dst) && !skb_is_gso(skb)) { /* Again, force OUTPUT device used as source address */ skb->dev = dst->dev; icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, dst_mtu(dst), skb->dev); IP6_INC_STATS_BH(net, ip6_dst_idev(dst), IPSTATS_MIB_INTOOBIGERRORS); IP6_INC_STATS_BH(net, ip6_dst_idev(dst), IPSTATS_MIB_FRAGFAILS); kfree_skb(skb); return -EMSGSIZE; } /* * We try to optimize forwarding of VE packets: * do not decrement TTL (and so save skb_cow) * during forwarding of outgoing pkts from VE. * For incoming pkts we still do ttl decr, * since such skb is not cloned and does not require * actual cow. So, there is at least one place * in pkts path with mandatory ttl decr, that is * sufficient to prevent routing loops. */ hdr = ipv6_hdr(skb); if (skb->dev->features & NETIF_F_VENET) /* src is VENET device */ goto no_ttl_decr; if (skb_cow(skb, dst->dev->hard_header_len)) { IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTDISCARDS); goto drop; } hdr = ipv6_hdr(skb); /* Mangling hops number delayed to point after skb COW */ hdr->hop_limit--; no_ttl_decr: IP6_INC_STATS_BH(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTFORWDATAGRAMS); return NF_HOOK(PF_INET6, NF_INET_FORWARD, skb, skb->dev, dst->dev, ip6_forward_finish); error: IP6_INC_STATS_BH(net, ip6_dst_idev(dst), IPSTATS_MIB_INADDRERRORS); drop: kfree_skb(skb); return -EINVAL; }
int ip_forward(struct sk_buff *skb) { struct iphdr *iph; /* Our header */ struct rtable *rt; /* Route we use */ struct ip_options * opt = &(IPCB(skb)->opt); if (skb_warn_if_lro(skb)) goto drop; if (!xfrm4_policy_check(NULL, XFRM_POLICY_FWD, skb)) goto drop; if (IPCB(skb)->opt.router_alert && ip_call_ra_chain(skb)) return NET_RX_SUCCESS; if (skb->pkt_type != PACKET_HOST) goto drop; skb_forward_csum(skb); /* * According to the RFC, we must first decrease the TTL field. If * that reaches zero, we must reply an ICMP control message telling * that the packet's lifetime expired. */ if (ip_hdr(skb)->ttl <= 1) goto too_many_hops; if (!xfrm4_route_forward(skb)) goto drop; rt = skb->rtable; if (opt->is_strictroute && rt->rt_dst != rt->rt_gateway) goto sr_failed; if (unlikely(skb->len > dst_mtu(&rt->u.dst) && !skb_is_gso(skb) && (ip_hdr(skb)->frag_off & htons(IP_DF))) && !skb->local_df) { IP_INC_STATS(dev_net(rt->u.dst.dev), IPSTATS_MIB_FRAGFAILS); icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(dst_mtu(&rt->u.dst))); goto drop; } /* We are about to mangle packet. Copy it! */ #if 0 if( (LL_RESERVED_SPACE(rt->u.dst.dev)+rt->u.dst.header_len) > skb_headroom(skb)) { printk("=========%s(%d),dst.dev(%s),reserved(%d),header_len(%d),hard_header_len(%d),needed_headroom(%d)\n",__FUNCTION__,__LINE__,rt->u.dst.dev->name,LL_RESERVED_SPACE(rt->u.dst.dev), rt->u.dst.header_len,rt->u.dst.dev->hard_header_len,rt->u.dst.dev->needed_headroom); printk("======%s(%d),skb->headroom(%d)\n",__FUNCTION__,__LINE__,skb_headroom(skb)); } #endif if (skb_cow(skb, LL_RESERVED_SPACE(rt->u.dst.dev)+rt->u.dst.header_len)) goto drop; iph = ip_hdr(skb); /* Decrease ttl after skb cow done */ ip_decrease_ttl(iph); /* * We now generate an ICMP HOST REDIRECT giving the route * we calculated. */ if (rt->rt_flags&RTCF_DOREDIRECT && !opt->srr && !skb_sec_path(skb)) ip_rt_send_redirect(skb); skb->priority = rt_tos2priority(iph->tos); return NF_HOOK(PF_INET, NF_INET_FORWARD, skb, skb->dev, rt->u.dst.dev, ip_forward_finish); sr_failed: /* * Strict routing permits no gatewaying */ icmp_send(skb, ICMP_DEST_UNREACH, ICMP_SR_FAILED, 0); goto drop; too_many_hops: /* Tell the sender its packet died... */ IP_INC_STATS_BH(dev_net(skb->dst->dev), IPSTATS_MIB_INHDRERRORS); icmp_send(skb, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL, 0); drop: kfree_skb(skb); return NET_RX_DROP; }