/* * Handle firewalling * Linux ethernet bridge * * Authors: * Lennert Buytenhek * Bart De Schuymer (maintainer) * * Changes: * Apr 29 2003: physdev module support (bdschuym) * Jun 19 2003: let arptables see bridged ARP traffic (bdschuym) * Oct 06 2003: filter encapsulated IP/ARP VLAN traffic on untagged bridge * (bdschuym) * Sep 01 2004: add IPv6 filtering (bdschuym) * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. * * Lennert dedicates this file to Kerstin Wurdinger. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "br_private.h" #ifdef CONFIG_SYSCTL #include #endif #define skb_origaddr(skb) (((struct bridge_skb_cb *) \ (skb->nf_bridge->data))->daddr.ipv4) #define store_orig_dstaddr(skb) (skb_origaddr(skb) = ip_hdr(skb)->daddr) #define dnat_took_place(skb) (skb_origaddr(skb) != ip_hdr(skb)->daddr) #ifdef CONFIG_SYSCTL static struct ctl_table_header *brnf_sysctl_header; static int brnf_call_iptables __read_mostly = 1; static int brnf_call_ip6tables __read_mostly = 1; static int brnf_call_arptables __read_mostly = 1; static int brnf_filter_vlan_tagged __read_mostly = 1; static int brnf_filter_pppoe_tagged __read_mostly = 1; #else #define brnf_filter_vlan_tagged 1 #define brnf_filter_pppoe_tagged 1 #endif static inline __be16 vlan_proto(const struct sk_buff *skb) { return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto; } #define IS_VLAN_IP(skb) \ (skb->protocol == htons(ETH_P_8021Q) && \ vlan_proto(skb) == htons(ETH_P_IP) && \ brnf_filter_vlan_tagged) #define IS_VLAN_IPV6(skb) \ (skb->protocol == htons(ETH_P_8021Q) && \ vlan_proto(skb) == htons(ETH_P_IPV6) &&\ brnf_filter_vlan_tagged) #define IS_VLAN_ARP(skb) \ (skb->protocol == htons(ETH_P_8021Q) && \ vlan_proto(skb) == htons(ETH_P_ARP) && \ brnf_filter_vlan_tagged) static inline __be16 pppoe_proto(const struct sk_buff *skb) { return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN + sizeof(struct pppoe_hdr))); } #define IS_PPPOE_IP(skb) \ (skb->protocol == htons(ETH_P_PPP_SES) && \ pppoe_proto(skb) == htons(PPP_IP) && \ brnf_filter_pppoe_tagged) #define IS_PPPOE_IPV6(skb) \ (skb->protocol == htons(ETH_P_PPP_SES) && \ pppoe_proto(skb) == htons(PPP_IPV6) && \ brnf_filter_pppoe_tagged) /* * Initialize bogus route table used to keep netfilter happy. * Currently, we fill in the PMTU entry because netfilter * refragmentation needs it, and the rt_flags entry because * ipt_REJECT needs it. Future netfilter modules might * require us to fill additional fields. */ void br_netfilter_rtable_init(struct net_bridge *br) { struct rtable *rt = &br->fake_rtable; atomic_set(&rt->u.dst.__refcnt, 1); rt->u.dst.dev = br->dev; rt->u.dst.path = &rt->u.dst; rt->u.dst.metrics[RTAX_MTU - 1] = 1500; rt->u.dst.flags = DST_NOXFRM; } static inline struct rtable *bridge_parent_rtable(const struct net_device *dev) { struct net_bridge_port *port = rcu_dereference(dev->br_port); return port ? &port->br->fake_rtable : NULL; } static inline struct net_device *bridge_parent(const struct net_device *dev) { struct net_bridge_port *port = rcu_dereference(dev->br_port); return port ? port->br->dev : NULL; } static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb) { skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC); if (likely(skb->nf_bridge)) atomic_set(&(skb->nf_bridge->use), 1); return skb->nf_bridge; } static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb) { struct nf_bridge_info *nf_bridge = skb->nf_bridge; if (atomic_read(&nf_bridge->use) > 1) { struct nf_bridge_info *tmp = nf_bridge_alloc(skb); if (tmp) { memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info)); atomic_set(&tmp->use, 1); nf_bridge_put(nf_bridge); } nf_bridge = tmp; } return nf_bridge; } static inline void nf_bridge_push_encap_header(struct sk_buff *skb) { unsigned int len = nf_bridge_encap_header_len(skb); skb_push(skb, len); skb->network_header -= len; } static inline void nf_bridge_pull_encap_header(struct sk_buff *skb) { unsigned int len = nf_bridge_encap_header_len(skb); skb_pull(skb, len); skb->network_header += len; } static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb) { unsigned int len = nf_bridge_encap_header_len(skb); skb_pull_rcsum(skb, len); skb->network_header += len; } static inline void nf_bridge_save_header(struct sk_buff *skb) { int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb); skb_copy_from_linear_data_offset(skb, -header_size, skb->nf_bridge->data, header_size); } /* * When forwarding bridge frames, we save a copy of the original * header before processing. */ int nf_bridge_copy_header(struct sk_buff *skb) { int err; int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb); err = skb_cow_head(skb, header_size); if (err) return err; skb_copy_to_linear_data_offset(skb, -header_size, skb->nf_bridge->data, header_size); __skb_push(skb, nf_bridge_encap_header_len(skb)); return 0; } /* PF_BRIDGE/PRE_ROUTING *********************************************/ /* Undo the changes made for ip6tables PREROUTING and continue the * bridge PRE_ROUTING hook. */ static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb) { struct nf_bridge_info *nf_bridge = skb->nf_bridge; if (nf_bridge->mask & BRNF_PKT_TYPE) { skb->pkt_type = PACKET_OTHERHOST; nf_bridge->mask ^= BRNF_PKT_TYPE; } nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING; skb->rtable = bridge_parent_rtable(nf_bridge->physindev); if (!skb->rtable) { kfree_skb(skb); return 0; } dst_hold(&skb->rtable->u.dst); skb->dev = nf_bridge->physindev; nf_bridge_push_encap_header(skb); NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, br_handle_frame_finish, 1); return 0; } static void __br_dnat_complain(void) { static unsigned long last_complaint; if (jiffies - last_complaint >= 5 * HZ) { printk(KERN_WARNING "Performing cross-bridge DNAT requires IP " "forwarding to be enabled\n"); last_complaint = jiffies; } } /* This requires some explaining. If DNAT has taken place, * we will need to fix up the destination Ethernet address, * and this is a tricky process. * * There are two cases to consider: * 1. The packet was DNAT'ed to a device in the same bridge * port group as it was received on. We can still bridge * the packet. * 2. The packet was DNAT'ed to a different device, either * a non-bridged device or another bridge port group. * The packet will need to be routed. * * The correct way of distinguishing between these two cases is to * call ip_route_input() and to look at skb->dst->dev, which is * changed to the destination device if ip_route_input() succeeds. * * Let us first consider the case that ip_route_input() succeeds: * * If skb->dst->dev equals the logical bridge device the packet * came in on, we can consider this bridging. The packet is passed * through the neighbour output function to build a new destination * MAC address, which will make the packet enter br_nf_local_out() * not much later. In that function it is assured that the iptables * FORWARD chain is traversed for the packet. * * Otherwise, the packet is considered to be routed and we just * change the destination MAC address so that the packet will * later be passed up to the IP stack to be routed. For a redirected * packet, ip_route_input() will give back the localhost as output device, * which differs from the bridge device. * * Let us now consider the case that ip_route_input() fails: * * This can be because the destination address is martian, in which case * the packet will be dropped. * After a "echo '0' > /proc/sys/net/ipv4/ip_forward" ip_route_input() * will fail, while __ip_route_output_key() will return success. The source * address for __ip_route_output_key() is set to zero, so __ip_route_output_key * thinks we're handling a locally generated packet and won't care * if IP forwarding is allowed. We send a warning message to the users's * log telling her to put IP forwarding on. * * ip_route_input() will also fail if there is no route available. * In that case we just drop the packet. * * --Lennert, 20020411 * --Bart, 20020416 (updated) * --Bart, 20021007 (updated) * --Bart, 20062711 (updated) */ static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb) { if (skb->pkt_type == PACKET_OTHERHOST) { skb->pkt_type = PACKET_HOST; skb->nf_bridge->mask |= BRNF_PKT_TYPE; } skb->nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING; skb->dev = bridge_parent(skb->dev); if (skb->dev) { struct dst_entry *dst = skb->dst; nf_bridge_pull_encap_header(skb); if (dst->hh) return neigh_hh_output(dst->hh, skb); else if (dst->neighbour) return dst->neighbour->output(skb); } kfree_skb(skb); return 0; } static int br_nf_pre_routing_finish(struct sk_buff *skb) { struct net_device *dev = skb->dev; struct iphdr *iph = ip_hdr(skb); struct nf_bridge_info *nf_bridge = skb->nf_bridge; int err; if (nf_bridge->mask & BRNF_PKT_TYPE) { skb->pkt_type = PACKET_OTHERHOST; nf_bridge->mask ^= BRNF_PKT_TYPE; } nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING; if (dnat_took_place(skb)) { if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) { struct rtable *rt; struct flowi fl = { .nl_u = { .ip4_u = { .daddr = iph->daddr, .saddr = 0, .tos = RT_TOS(iph->tos) }, }, .proto = 0, }; struct in_device *in_dev = in_dev_get(dev); /* If err equals -EHOSTUNREACH the error is due to a * martian destination or due to the fact that * forwarding is disabled. For most martian packets, * ip_route_output_key() will fail. It won't fail for 2 types of * martian destinations: loopback destinations and destination * 0.0.0.0. In both cases the packet will be dropped because the * destination is the loopback device and not the bridge. */ if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev)) goto free_skb; if (!ip_route_output_key(&init_net, &rt, &fl)) { /* - Bridged-and-DNAT'ed traffic doesn't * require ip_forwarding. */ if (((struct dst_entry *)rt)->dev == dev) { skb->dst = (struct dst_entry *)rt; goto bridged_dnat; } /* we are sure that forwarding is disabled, so printing * this message is no problem. Note that the packet could * still have a martian destination address, in which case * the packet could be dropped even if forwarding were enabled */ __br_dnat_complain(); dst_release((struct dst_entry *)rt); } free_skb: kfree_skb(skb); return 0; } else { if (skb->dst->dev == dev) { bridged_dnat: /* Tell br_nf_local_out this is a * bridged frame */ nf_bridge->mask |= BRNF_BRIDGED_DNAT; skb->dev = nf_bridge->physindev; nf_bridge_push_encap_header(skb); NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, br_nf_pre_routing_finish_bridge, 1); return 0; } memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN); skb->pkt_type = PACKET_HOST; } } else { skb->rtable = bridge_parent_rtable(nf_bridge->physindev); if (!skb->rtable) { kfree_skb(skb); return 0; } dst_hold(&skb->rtable->u.dst); } skb->dev = nf_bridge->physindev; nf_bridge_push_encap_header(skb); NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, br_handle_frame_finish, 1); return 0; } /* Some common code for IPv4/IPv6 */ static struct net_device *setup_pre_routing(struct sk_buff *skb) { struct nf_bridge_info *nf_bridge = skb->nf_bridge; if (skb->pkt_type == PACKET_OTHERHOST) { skb->pkt_type = PACKET_HOST; nf_bridge->mask |= BRNF_PKT_TYPE; } nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING; nf_bridge->physindev = skb->dev; skb->dev = bridge_parent(skb->dev); return skb->dev; } /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */ static int check_hbh_len(struct sk_buff *skb) { unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1); u32 pkt_len; const unsigned char *nh = skb_network_header(skb); int off = raw - nh; int len = (raw[1] + 1) << 3; if ((raw + len) - skb->data > skb_headlen(skb)) goto bad; off += 2; len -= 2; while (len > 0) { int optlen = nh[off + 1] + 2; switch (nh[off]) { case IPV6_TLV_PAD0: optlen = 1; break; case IPV6_TLV_PADN: break; case IPV6_TLV_JUMBO: if (nh[off + 1] != 4 || (off & 3) != 2) goto bad; pkt_len = ntohl(*(__be32 *) (nh + off + 2)); if (pkt_len <= IPV6_MAXPLEN || ipv6_hdr(skb)->payload_len) goto bad; if (pkt_len > skb->len - sizeof(struct ipv6hdr)) goto bad; if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) goto bad; nh = skb_network_header(skb); break; default: if (optlen > len) goto bad; break; } off += optlen; len -= optlen; } if (len == 0) return 0; bad: return -1; } /* Replicate the checks that IPv6 does on packet reception and pass the packet * to ip6tables, which doesn't support NAT, so things are fairly simple. */ static unsigned int br_nf_pre_routing_ipv6(unsigned int hook, struct sk_buff *skb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct ipv6hdr *hdr; u32 pkt_len; if (skb->len < sizeof(struct ipv6hdr)) goto inhdr_error; if (!pskb_may_pull(skb, sizeof(struct ipv6hdr))) goto inhdr_error; hdr = ipv6_hdr(skb); if (hdr->version != 6) goto inhdr_error; pkt_len = ntohs(hdr->payload_len); if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) { if (pkt_len + sizeof(struct ipv6hdr) > skb->len) goto inhdr_error; if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) goto inhdr_error; } if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb)) goto inhdr_error; nf_bridge_put(skb->nf_bridge); if (!nf_bridge_alloc(skb)) return NF_DROP; if (!setup_pre_routing(skb)) return NF_DROP; NF_HOOK(PF_INET6, NF_INET_PRE_ROUTING, skb, skb->dev, NULL, br_nf_pre_routing_finish_ipv6); return NF_STOLEN; inhdr_error: return NF_DROP; } /* Direct IPv6 traffic to br_nf_pre_routing_ipv6. * Replicate the checks that IPv4 does on packet reception. * Set skb->dev to the bridge device (i.e. parent of the * receiving device) to make netfilter happy, the REDIRECT * target in particular. Save the original destination IP * address to be able to detect DNAT afterwards. */ static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff *skb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct iphdr *iph; __u32 len = nf_bridge_encap_header_len(skb); if (unlikely(!pskb_may_pull(skb, len))) goto out; if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb)) { #ifdef CONFIG_SYSCTL if (!brnf_call_ip6tables) return NF_ACCEPT; #endif nf_bridge_pull_encap_header_rcsum(skb); return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn); } #ifdef CONFIG_SYSCTL if (!brnf_call_iptables) return NF_ACCEPT; #endif if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb) && !IS_PPPOE_IP(skb)) return NF_ACCEPT; nf_bridge_pull_encap_header_rcsum(skb); if (!pskb_may_pull(skb, sizeof(struct iphdr))) goto inhdr_error; iph = ip_hdr(skb); if (iph->ihl < 5 || iph->version != 4) goto inhdr_error; if (!pskb_may_pull(skb, 4 * iph->ihl)) goto inhdr_error; iph = ip_hdr(skb); if (ip_fast_csum((__u8 *) iph, iph->ihl) != 0) goto inhdr_error; len = ntohs(iph->tot_len); if (skb->len < len || len < 4 * iph->ihl) goto inhdr_error; pskb_trim_rcsum(skb, len); nf_bridge_put(skb->nf_bridge); if (!nf_bridge_alloc(skb)) return NF_DROP; if (!setup_pre_routing(skb)) return NF_DROP; store_orig_dstaddr(skb); NF_HOOK(PF_INET, NF_INET_PRE_ROUTING, skb, skb->dev, NULL, br_nf_pre_routing_finish); return NF_STOLEN; inhdr_error: // IP_INC_STATS_BH(IpInHdrErrors); out: return NF_DROP; } /* PF_BRIDGE/LOCAL_IN ************************************************/ /* The packet is locally destined, which requires a real * dst_entry, so detach the fake one. On the way up, the * packet would pass through PRE_ROUTING again (which already * took place when the packet entered the bridge), but we * register an IPv4 PRE_ROUTING 'sabotage' hook that will * prevent this from happening. */ static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff *skb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { if (skb->rtable && skb->rtable == bridge_parent_rtable(in)) { dst_release(&skb->rtable->u.dst); skb->rtable = NULL; } return NF_ACCEPT; } /* PF_BRIDGE/FORWARD *************************************************/ static int br_nf_forward_finish(struct sk_buff *skb) { struct nf_bridge_info *nf_bridge = skb->nf_bridge; struct net_device *in; if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) { in = nf_bridge->physindev; if (nf_bridge->mask & BRNF_PKT_TYPE) { skb->pkt_type = PACKET_OTHERHOST; nf_bridge->mask ^= BRNF_PKT_TYPE; } } else { in = *((struct net_device **)(skb->cb)); } nf_bridge_push_encap_header(skb); NF_HOOK_THRESH(PF_BRIDGE, NF_BR_FORWARD, skb, in, skb->dev, br_forward_finish, 1); return 0; } /* This is the 'purely bridged' case. For IP, we pass the packet to * netfilter with indev and outdev set to the bridge device, * but we are still able to filter on the 'real' indev/outdev * because of the physdev module. For ARP, indev and outdev are the * bridge ports. */ static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff *skb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct nf_bridge_info *nf_bridge; struct net_device *parent; int pf; if (!skb->nf_bridge) return NF_ACCEPT; /* Need exclusive nf_bridge_info since we might have multiple * different physoutdevs. */ if (!nf_bridge_unshare(skb)) return NF_DROP; parent = bridge_parent(out); if (!parent) return NF_DROP; if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb)) pf = PF_INET; else pf = PF_INET6; nf_bridge_pull_encap_header(skb); nf_bridge = skb->nf_bridge; if (skb->pkt_type == PACKET_OTHERHOST) { skb->pkt_type = PACKET_HOST; nf_bridge->mask |= BRNF_PKT_TYPE; } /* The physdev module checks on this */ nf_bridge->mask |= BRNF_BRIDGED; nf_bridge->physoutdev = skb->dev; NF_HOOK(pf, NF_INET_FORWARD, skb, bridge_parent(in), parent, br_nf_forward_finish); return NF_STOLEN; } static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct net_device **d = (struct net_device **)(skb->cb); #ifdef CONFIG_SYSCTL if (!brnf_call_arptables) return NF_ACCEPT; #endif if (skb->protocol != htons(ETH_P_ARP)) { if (!IS_VLAN_ARP(skb)) return NF_ACCEPT; nf_bridge_pull_encap_header(skb); } if (arp_hdr(skb)->ar_pln != 4) { if (IS_VLAN_ARP(skb)) nf_bridge_push_encap_header(skb); return NF_ACCEPT; } *d = (struct net_device *)in; NF_HOOK(NF_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in, (struct net_device *)out, br_nf_forward_finish); return NF_STOLEN; } /* PF_BRIDGE/LOCAL_OUT *********************************************** * * This function sees both locally originated IP packets and forwarded * IP packets (in both cases the destination device is a bridge * device). It also sees bridged-and-DNAT'ed packets. * * If (nf_bridge->mask & BRNF_BRIDGED_DNAT) then the packet is bridged * and we fake the PF_BRIDGE/FORWARD hook. The function br_nf_forward() * will then fake the PF_INET/FORWARD hook. br_nf_local_out() has priority * NF_BR_PRI_FIRST, so no relevant PF_BRIDGE/INPUT functions have been nor * will be executed. */ static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff *skb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct net_device *realindev; struct nf_bridge_info *nf_bridge; if (!skb->nf_bridge) return NF_ACCEPT; /* Need exclusive nf_bridge_info since we might have multiple * different physoutdevs. */ if (!nf_bridge_unshare(skb)) return NF_DROP; nf_bridge = skb->nf_bridge; if (!(nf_bridge->mask & BRNF_BRIDGED_DNAT)) return NF_ACCEPT; /* Bridged, take PF_BRIDGE/FORWARD. * (see big note in front of br_nf_pre_routing_finish) */ nf_bridge->physoutdev = skb->dev; realindev = nf_bridge->physindev; if (nf_bridge->mask & BRNF_PKT_TYPE) { skb->pkt_type = PACKET_OTHERHOST; nf_bridge->mask ^= BRNF_PKT_TYPE; } nf_bridge_push_encap_header(skb); NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, realindev, skb->dev, br_forward_finish); return NF_STOLEN; } static int br_nf_dev_queue_xmit(struct sk_buff *skb) { if (skb->protocol == htons(ETH_P_IP) && skb->len > skb->dev->mtu && !skb_is_gso(skb)) return ip_fragment(skb, br_dev_queue_push_xmit); else return br_dev_queue_push_xmit(skb); } /* PF_BRIDGE/POST_ROUTING ********************************************/ static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff *skb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct nf_bridge_info *nf_bridge = skb->nf_bridge; struct net_device *realoutdev = bridge_parent(skb->dev); int pf; #ifdef CONFIG_NETFILTER_DEBUG /* Be very paranoid. This probably won't happen anymore, but let's * keep the check just to be sure... */ if (skb_mac_header(skb) < skb->head || skb_mac_header(skb) + ETH_HLEN > skb->data) { printk(KERN_CRIT "br_netfilter: Argh!! br_nf_post_routing: " "bad mac.raw pointer.\n"); goto print_error; } #endif if (!nf_bridge) return NF_ACCEPT; if (!(nf_bridge->mask & (BRNF_BRIDGED | BRNF_BRIDGED_DNAT))) return NF_ACCEPT; if (!realoutdev) return NF_DROP; if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb)) pf = PF_INET; else pf = PF_INET6; #ifdef CONFIG_NETFILTER_DEBUG if (skb->dst == NULL) { printk(KERN_INFO "br_netfilter post_routing: skb->dst == NULL\n"); goto print_error; } #endif /* We assume any code from br_dev_queue_push_xmit onwards doesn't care * about the value of skb->pkt_type. */ if (skb->pkt_type == PACKET_OTHERHOST) { skb->pkt_type = PACKET_HOST; nf_bridge->mask |= BRNF_PKT_TYPE; } nf_bridge_pull_encap_header(skb); nf_bridge_save_header(skb); NF_HOOK(pf, NF_INET_POST_ROUTING, skb, NULL, realoutdev, br_nf_dev_queue_xmit); return NF_STOLEN; #ifdef CONFIG_NETFILTER_DEBUG print_error: if (skb->dev != NULL) { printk("[%s]", skb->dev->name); if (realoutdev) printk("[%s]", realoutdev->name); } printk(" head:%p, raw:%p, data:%p\n", skb->head, skb_mac_header(skb), skb->data); dump_stack(); return NF_ACCEPT; #endif } /* IP/SABOTAGE *****************************************************/ /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING * for the second time. */ static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff *skb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { if (skb->nf_bridge && !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) { return NF_STOP; } return NF_ACCEPT; } /* For br_nf_local_out we need (prio = NF_BR_PRI_FIRST), to insure that innocent * PF_BRIDGE/NF_BR_LOCAL_OUT functions don't get bridged traffic as input. * For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because * ip_refrag() can return NF_STOLEN. */ static struct nf_hook_ops br_nf_ops[] __read_mostly = { { .hook = br_nf_pre_routing, .owner = THIS_MODULE, .pf = PF_BRIDGE, .hooknum = NF_BR_PRE_ROUTING, .priority = NF_BR_PRI_BRNF, }, { .hook = br_nf_local_in, .owner = THIS_MODULE, .pf = PF_BRIDGE, .hooknum = NF_BR_LOCAL_IN, .priority = NF_BR_PRI_BRNF, }, { .hook = br_nf_forward_ip, .owner = THIS_MODULE, .pf = PF_BRIDGE, .hooknum = NF_BR_FORWARD, .priority = NF_BR_PRI_BRNF - 1, }, { .hook = br_nf_forward_arp, .owner = THIS_MODULE, .pf = PF_BRIDGE, .hooknum = NF_BR_FORWARD, .priority = NF_BR_PRI_BRNF, }, { .hook = br_nf_local_out, .owner = THIS_MODULE, .pf = PF_BRIDGE, .hooknum = NF_BR_LOCAL_OUT, .priority = NF_BR_PRI_FIRST, }, { .hook = br_nf_post_routing, .owner = THIS_MODULE, .pf = PF_BRIDGE, .hooknum = NF_BR_POST_ROUTING, .priority = NF_BR_PRI_LAST, }, { .hook = ip_sabotage_in, .owner = THIS_MODULE, .pf = PF_INET, .hooknum = NF_INET_PRE_ROUTING, .priority = NF_IP_PRI_FIRST, }, { .hook = ip_sabotage_in, .owner = THIS_MODULE, .pf = PF_INET6, .hooknum = NF_INET_PRE_ROUTING, .priority = NF_IP6_PRI_FIRST, }, }; #ifdef CONFIG_SYSCTL static int brnf_sysctl_call_tables(ctl_table * ctl, int write, struct file *filp, void __user * buffer, size_t * lenp, loff_t * ppos) { int ret; ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos); if (write && *(int *)(ctl->data)) *(int *)(ctl->data) = 1; return ret; } static ctl_table brnf_table[] = { { .procname = "bridge-nf-call-arptables", .data = &brnf_call_arptables, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &brnf_sysctl_call_tables, }, { .procname = "bridge-nf-call-iptables", .data = &brnf_call_iptables, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &brnf_sysctl_call_tables, }, { .procname = "bridge-nf-call-ip6tables", .data = &brnf_call_ip6tables, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &brnf_sysctl_call_tables, }, { .procname = "bridge-nf-filter-vlan-tagged", .data = &brnf_filter_vlan_tagged, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &brnf_sysctl_call_tables, }, { .procname = "bridge-nf-filter-pppoe-tagged", .data = &brnf_filter_pppoe_tagged, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &brnf_sysctl_call_tables, }, { .ctl_name = 0 } }; static struct ctl_path brnf_path[] = { { .procname = "net", .ctl_name = CTL_NET, }, { .procname = "bridge", .ctl_name = NET_BRIDGE, }, { } }; #endif int __init br_netfilter_init(void) { int ret; ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops)); if (ret < 0) return ret; #ifdef CONFIG_SYSCTL brnf_sysctl_header = register_sysctl_paths(brnf_path, brnf_table); if (brnf_sysctl_header == NULL) { printk(KERN_WARNING "br_netfilter: can't register to sysctl.\n"); nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops)); return -ENOMEM; } #endif printk(KERN_NOTICE "Bridge firewalling registered\n"); return 0; } void br_netfilter_fini(void) { nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops)); #ifdef CONFIG_SYSCTL unregister_sysctl_table(brnf_sysctl_header); #endif }