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br_netfilter.c
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/* * Handle firewalling * Linux ethernet bridge * * Authors: * Lennert Buytenhek <buytenh@gnu.org> * Bart De Schuymer (maintainer) <bdschuym@pandora.be> * * 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 <linux/module.h> #include <linux/kernel.h> #include <linux/ip.h> #include <linux/netdevice.h> #include <linux/skbuff.h> #include <linux/if_arp.h> #include <linux/if_ether.h> #include <linux/if_vlan.h> #include <linux/netfilter_bridge.h> #include <linux/netfilter_ipv4.h> #include <linux/netfilter_ipv6.h> #include <linux/netfilter_arp.h> #include <linux/in_route.h> #include <net/ip.h> #include <net/ipv6.h> #include <net/route.h> #include <asm/uaccess.h> #include <asm/checksum.h> #include "br_private.h" #ifdef CONFIG_SYSCTL #include <linux/sysctl.h> #endif #define skb_origaddr(skb) (((struct bridge_skb_cb *) \ (skb->nf_bridge->data))->daddr.ipv4) #define store_orig_dstaddr(skb) (skb_origaddr(skb) = (skb)->nh.iph->daddr) #define dnat_took_place(skb) (skb_origaddr(skb) != (skb)->nh.iph->daddr) #ifdef CONFIG_SYSCTL static struct ctl_table_header *brnf_sysctl_header; static int brnf_call_iptables = 1; static int brnf_call_ip6tables = 1; static int brnf_call_arptables = 1; static int brnf_filter_vlan_tagged = 1; #else #define brnf_filter_vlan_tagged 1 #endif #define IS_VLAN_IP (skb->protocol == __constant_htons(ETH_P_8021Q) && \ hdr->h_vlan_encapsulated_proto == __constant_htons(ETH_P_IP) && \ brnf_filter_vlan_tagged) #define IS_VLAN_IPV6 (skb->protocol == __constant_htons(ETH_P_8021Q) && \ hdr->h_vlan_encapsulated_proto == __constant_htons(ETH_P_IPV6) && \ brnf_filter_vlan_tagged) #define IS_VLAN_ARP (skb->protocol == __constant_htons(ETH_P_8021Q) && \ hdr->h_vlan_encapsulated_proto == __constant_htons(ETH_P_ARP) && \ brnf_filter_vlan_tagged) /* We need these fake structures to make netfilter happy -- * lots of places assume that skb->dst != NULL, which isn't * all that unreasonable. * * 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. */ static struct net_device __fake_net_device = { .hard_header_len = ETH_HLEN }; static struct rtable __fake_rtable = { .u = { .dst = { .__refcnt = ATOMIC_INIT(1), .dev = &__fake_net_device, .path = &__fake_rtable.u.dst, .metrics = {[RTAX_MTU - 1] = 1500}, .flags = DST_NOXFRM, } }, .rt_flags = 0, }; 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; } /* 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->dst = (struct dst_entry *)&__fake_rtable; dst_hold(skb->dst); skb->dev = nf_bridge->physindev; if (skb->protocol == __constant_htons(ETH_P_8021Q)) { skb_push(skb, VLAN_HLEN); skb->nh.raw -= VLAN_HLEN; } 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. We then call * skb->dst->output() 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. * * Let us now consider the case that ip_route_input() fails: * * 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) */ 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) kfree_skb(skb); else { if (skb->protocol == __constant_htons(ETH_P_8021Q)) { skb_pull(skb, VLAN_HLEN); skb->nh.raw += VLAN_HLEN; } skb->dst->output(skb); } return 0; } static int br_nf_pre_routing_finish(struct sk_buff *skb) { struct net_device *dev = skb->dev; struct iphdr *iph = skb->nh.iph; 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; if (dnat_took_place(skb)) { if (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}; if (!ip_route_output_key(&rt, &fl)) { /* - Bridged-and-DNAT'ed traffic doesn't * require ip_forwarding. * - Deal with redirected traffic. */ if (((struct dst_entry *)rt)->dev == dev || rt->rt_type == RTN_LOCAL) { skb->dst = (struct dst_entry *)rt; goto bridged_dnat; } __br_dnat_complain(); dst_release((struct dst_entry *)rt); } 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; if (skb->protocol == __constant_htons(ETH_P_8021Q)) { skb_push(skb, VLAN_HLEN); skb->nh.raw -= VLAN_HLEN; } 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->dst = (struct dst_entry *)&__fake_rtable; dst_hold(skb->dst); } skb->dev = nf_bridge->physindev; if (skb->protocol == __constant_htons(ETH_P_8021Q)) { skb_push(skb, VLAN_HLEN); skb->nh.raw -= VLAN_HLEN; } 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*)(skb->nh.ipv6h+1); u32 pkt_len; int off = raw - skb->nh.raw; 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 = skb->nh.raw[off+1]+2; switch (skb->nh.raw[off]) { case IPV6_TLV_PAD0: optlen = 1; break; case IPV6_TLV_PADN: break; case IPV6_TLV_JUMBO: if (skb->nh.raw[off+1] != 4 || (off&3) != 2) goto bad; pkt_len = ntohl(*(u32*)(skb->nh.raw+off+2)); if (pkt_len <= IPV6_MAXPLEN || skb->nh.ipv6h->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; 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; struct nf_bridge_info *nf_bridge; if (skb->len < sizeof(struct ipv6hdr)) goto inhdr_error; if (!pskb_may_pull(skb, sizeof(struct ipv6hdr))) goto inhdr_error; hdr = skb->nh.ipv6h; 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 (pkt_len + sizeof(struct ipv6hdr) < skb->len) { if (__pskb_trim(skb, pkt_len + sizeof(struct ipv6hdr))) goto inhdr_error; if (skb->ip_summed == CHECKSUM_HW) skb->ip_summed = CHECKSUM_NONE; } } if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb)) goto inhdr_error; nf_bridge_put(skb->nf_bridge); if ((nf_bridge = nf_bridge_alloc(skb)) == NULL) return NF_DROP; if (!setup_pre_routing(skb)) return NF_DROP; NF_HOOK(PF_INET6, NF_IP6_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 **pskb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct iphdr *iph; __u32 len; struct sk_buff *skb = *pskb; struct nf_bridge_info *nf_bridge; struct vlan_ethhdr *hdr = vlan_eth_hdr(*pskb); if (skb->protocol == __constant_htons(ETH_P_IPV6) || IS_VLAN_IPV6) { #ifdef CONFIG_SYSCTL if (!brnf_call_ip6tables) return NF_ACCEPT; #endif if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL) goto out; if (skb->protocol == __constant_htons(ETH_P_8021Q)) { u8 *vhdr = skb->data; skb_pull(skb, VLAN_HLEN); skb_postpull_rcsum(skb, vhdr, VLAN_HLEN); skb->nh.raw += VLAN_HLEN; } 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 != __constant_htons(ETH_P_IP) && !IS_VLAN_IP) return NF_ACCEPT; if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL) goto out; if (skb->protocol == __constant_htons(ETH_P_8021Q)) { u8 *vhdr = skb->data; skb_pull(skb, VLAN_HLEN); skb_postpull_rcsum(skb, vhdr, VLAN_HLEN); skb->nh.raw += VLAN_HLEN; } if (!pskb_may_pull(skb, sizeof(struct iphdr))) goto inhdr_error; iph = skb->nh.iph; if (iph->ihl < 5 || iph->version != 4) goto inhdr_error; if (!pskb_may_pull(skb, 4*iph->ihl)) goto inhdr_error; iph = skb->nh.iph; 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; if (skb->len > len) { __pskb_trim(skb, len); if (skb->ip_summed == CHECKSUM_HW) skb->ip_summed = CHECKSUM_NONE; } nf_bridge_put(skb->nf_bridge); if ((nf_bridge = nf_bridge_alloc(skb)) == NULL) return NF_DROP; if (!setup_pre_routing(skb)) return NF_DROP; store_orig_dstaddr(skb); NF_HOOK(PF_INET, NF_IP_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 **pskb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct sk_buff *skb = *pskb; if (skb->dst == (struct dst_entry *)&__fake_rtable) { dst_release(skb->dst); skb->dst = 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; struct vlan_ethhdr *hdr = vlan_eth_hdr(skb); if (skb->protocol != __constant_htons(ETH_P_ARP) && !IS_VLAN_ARP) { 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)); } if (skb->protocol == __constant_htons(ETH_P_8021Q)) { skb_push(skb, VLAN_HLEN); skb->nh.raw -= VLAN_HLEN; } 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 **pskb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct sk_buff *skb = *pskb; struct nf_bridge_info *nf_bridge; struct vlan_ethhdr *hdr = vlan_eth_hdr(skb); struct net_device *parent; int pf; if (!skb->nf_bridge) return NF_ACCEPT; parent = bridge_parent(out); if (!parent) return NF_DROP; if (skb->protocol == __constant_htons(ETH_P_IP) || IS_VLAN_IP) pf = PF_INET; else pf = PF_INET6; if (skb->protocol == __constant_htons(ETH_P_8021Q)) { skb_pull(*pskb, VLAN_HLEN); (*pskb)->nh.raw += VLAN_HLEN; } 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_IP_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 **pskb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct sk_buff *skb = *pskb; struct vlan_ethhdr *hdr = vlan_eth_hdr(skb); struct net_device **d = (struct net_device **)(skb->cb); #ifdef CONFIG_SYSCTL if (!brnf_call_arptables) return NF_ACCEPT; #endif if (skb->protocol != __constant_htons(ETH_P_ARP)) { if (!IS_VLAN_ARP) return NF_ACCEPT; skb_pull(*pskb, VLAN_HLEN); (*pskb)->nh.raw += VLAN_HLEN; } if (skb->nh.arph->ar_pln != 4) { if (IS_VLAN_ARP) { skb_push(*pskb, VLAN_HLEN); (*pskb)->nh.raw -= VLAN_HLEN; } 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 ***********************************************/ static int br_nf_local_out_finish(struct sk_buff *skb) { if (skb->protocol == __constant_htons(ETH_P_8021Q)) { skb_push(skb, VLAN_HLEN); skb->nh.raw -= VLAN_HLEN; } NF_HOOK_THRESH(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev, br_forward_finish, NF_BR_PRI_FIRST + 1); return 0; } /* 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. * To be able to filter on the physical bridge devices (with the physdev * module), we steal packets destined to a bridge device away from the * PF_INET/FORWARD and PF_INET/OUTPUT hook functions, and give them back later, * when we have determined the real output device. This is done in here. * * 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. * Otherwise, if nf_bridge->physindev is NULL, the bridge-nf code never touched * this packet before, and so the packet was locally originated. We fake * the PF_INET/LOCAL_OUT hook. * Finally, if nf_bridge->physindev isn't NULL, then the packet was IP routed, * so we fake the PF_INET/FORWARD hook. ip_sabotage_out() makes sure * even routed packets that didn't arrive on a bridge interface have their * nf_bridge->physindev set. */ static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff **pskb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct net_device *realindev, *realoutdev; struct sk_buff *skb = *pskb; struct nf_bridge_info *nf_bridge; struct vlan_ethhdr *hdr = vlan_eth_hdr(skb); int pf; if (!skb->nf_bridge) return NF_ACCEPT; if (skb->protocol == __constant_htons(ETH_P_IP) || IS_VLAN_IP) pf = PF_INET; else pf = PF_INET6; #ifdef CONFIG_NETFILTER_DEBUG /* Sometimes we get packets with NULL ->dst here (for example, * running a dhcp client daemon triggers this). This should now * be fixed, but let's keep the check around. */ if (skb->dst == NULL) { printk(KERN_CRIT "br_netfilter: skb->dst == NULL."); return NF_ACCEPT; } #endif nf_bridge = skb->nf_bridge; nf_bridge->physoutdev = skb->dev; realindev = nf_bridge->physindev; /* Bridged, take PF_BRIDGE/FORWARD. * (see big note in front of br_nf_pre_routing_finish) */ if (nf_bridge->mask & BRNF_BRIDGED_DNAT) { if (nf_bridge->mask & BRNF_PKT_TYPE) { skb->pkt_type = PACKET_OTHERHOST; nf_bridge->mask ^= BRNF_PKT_TYPE; } if (skb->protocol == __constant_htons(ETH_P_8021Q)) { skb_push(skb, VLAN_HLEN); skb->nh.raw -= VLAN_HLEN; } NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, realindev, skb->dev, br_forward_finish); goto out; } realoutdev = bridge_parent(skb->dev); if (!realoutdev) return NF_DROP; #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE) /* iptables should match -o br0.x */ if (nf_bridge->netoutdev) realoutdev = nf_bridge->netoutdev; #endif if (skb->protocol == __constant_htons(ETH_P_8021Q)) { skb_pull(skb, VLAN_HLEN); (*pskb)->nh.raw += VLAN_HLEN; } /* IP forwarded traffic has a physindev, locally * generated traffic hasn't. */ if (realindev != NULL) { if (!(nf_bridge->mask & BRNF_DONT_TAKE_PARENT) ) { struct net_device *parent = bridge_parent(realindev); if (parent) realindev = parent; } NF_HOOK_THRESH(pf, NF_IP_FORWARD, skb, realindev, realoutdev, br_nf_local_out_finish, NF_IP_PRI_BRIDGE_SABOTAGE_FORWARD + 1); } else { NF_HOOK_THRESH(pf, NF_IP_LOCAL_OUT, skb, realindev, realoutdev, br_nf_local_out_finish, NF_IP_PRI_BRIDGE_SABOTAGE_LOCAL_OUT + 1); } out: return NF_STOLEN; } /* PF_BRIDGE/POST_ROUTING ********************************************/ static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff **pskb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct sk_buff *skb = *pskb; struct nf_bridge_info *nf_bridge = (*pskb)->nf_bridge; struct vlan_ethhdr *hdr = vlan_eth_hdr(skb); 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.raw < skb->head || skb->mac.raw + ETH_HLEN > skb->data) { printk(KERN_CRIT "br_netfilter: Argh!! br_nf_post_routing: " "bad mac.raw pointer."); goto print_error; } #endif if (!nf_bridge) return NF_ACCEPT; if (!realoutdev) return NF_DROP; if (skb->protocol == __constant_htons(ETH_P_IP) || IS_VLAN_IP) pf = PF_INET; else pf = PF_INET6; #ifdef CONFIG_NETFILTER_DEBUG if (skb->dst == NULL) { printk(KERN_CRIT "br_netfilter: skb->dst == NULL."); 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; } if (skb->protocol == __constant_htons(ETH_P_8021Q)) { skb_pull(skb, VLAN_HLEN); skb->nh.raw += VLAN_HLEN; } nf_bridge_save_header(skb); #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE) if (nf_bridge->netoutdev) realoutdev = nf_bridge->netoutdev; #endif NF_HOOK(pf, NF_IP_POST_ROUTING, skb, NULL, realoutdev, br_dev_queue_push_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.raw, skb->data); 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 **pskb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { if ((*pskb)->nf_bridge && !((*pskb)->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) { return NF_STOP; } return NF_ACCEPT; } /* Postpone execution of PF_INET(6)/FORWARD, PF_INET(6)/LOCAL_OUT * and PF_INET(6)/POST_ROUTING until we have done the forwarding * decision in the bridge code and have determined nf_bridge->physoutdev. */ static unsigned int ip_sabotage_out(unsigned int hook, struct sk_buff **pskb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct sk_buff *skb = *pskb; if ((out->hard_start_xmit == br_dev_xmit && okfn != br_nf_forward_finish && okfn != br_nf_local_out_finish && okfn != br_dev_queue_push_xmit) #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE) || ((out->priv_flags & IFF_802_1Q_VLAN) && VLAN_DEV_INFO(out)->real_dev->hard_start_xmit == br_dev_xmit) #endif ) { struct nf_bridge_info *nf_bridge; if (!skb->nf_bridge) { #ifdef CONFIG_SYSCTL /* This code is executed while in the IP(v6) stack, the version should be 4 or 6. We can't use skb->protocol because that isn't set on PF_INET(6)/LOCAL_OUT. */ struct iphdr *ip = skb->nh.iph; if (ip->version == 4 && !brnf_call_iptables) return NF_ACCEPT; else if (ip->version == 6 && !brnf_call_ip6tables) return NF_ACCEPT; #endif if (hook == NF_IP_POST_ROUTING) return NF_ACCEPT; if (!nf_bridge_alloc(skb)) return NF_DROP; } nf_bridge = skb->nf_bridge; /* This frame will arrive on PF_BRIDGE/LOCAL_OUT and we * will need the indev then. For a brouter, the real indev * can be a bridge port, so we make sure br_nf_local_out() * doesn't use the bridge parent of the indev by using * the BRNF_DONT_TAKE_PARENT mask. */ if (hook == NF_IP_FORWARD && nf_bridge->physindev == NULL) { nf_bridge->mask |= BRNF_DONT_TAKE_PARENT; nf_bridge->physindev = (struct net_device *)in; } #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE) /* the iptables outdev is br0.x, not br0 */ if (out->priv_flags & IFF_802_1Q_VLAN) nf_bridge->netoutdev = (struct net_device *)out; #endif 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[] = { { .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_IP_PRE_ROUTING, .priority = NF_IP_PRI_FIRST, }, { .hook = ip_sabotage_in, .owner = THIS_MODULE, .pf = PF_INET6, .hooknum = NF_IP6_PRE_ROUTING, .priority = NF_IP6_PRI_FIRST, }, { .hook = ip_sabotage_out, .owner = THIS_MODULE, .pf = PF_INET, .hooknum = NF_IP_FORWARD, .priority = NF_IP_PRI_BRIDGE_SABOTAGE_FORWARD, }, { .hook = ip_sabotage_out, .owner = THIS_MODULE, .pf = PF_INET6, .hooknum = NF_IP6_FORWARD, .priority = NF_IP6_PRI_BRIDGE_SABOTAGE_FORWARD, }, { .hook = ip_sabotage_out, .owner = THIS_MODULE, .pf = PF_INET, .hooknum = NF_IP_LOCAL_OUT, .priority = NF_IP_PRI_BRIDGE_SABOTAGE_LOCAL_OUT, }, { .hook = ip_sabotage_out, .owner = THIS_MODULE, .pf = PF_INET6, .hooknum = NF_IP6_LOCAL_OUT, .priority = NF_IP6_PRI_BRIDGE_SABOTAGE_LOCAL_OUT, }, { .hook = ip_sabotage_out, .owner = THIS_MODULE, .pf = PF_INET, .hooknum = NF_IP_POST_ROUTING, .priority = NF_IP_PRI_FIRST, }, { .hook = ip_sabotage_out, .owner = THIS_MODULE, .pf = PF_INET6, .hooknum = NF_IP6_POST_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[] = { { .ctl_name = NET_BRIDGE_NF_CALL_ARPTABLES, .procname = "bridge-nf-call-arptables", .data = &brnf_call_arptables, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &brnf_sysctl_call_tables, }, { .ctl_name = NET_BRIDGE_NF_CALL_IPTABLES, .procname = "bridge-nf-call-iptables", .data = &brnf_call_iptables, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &brnf_sysctl_call_tables, }, { .ctl_name = NET_BRIDGE_NF_CALL_IP6TABLES, .procname = "bridge-nf-call-ip6tables", .data = &brnf_call_ip6tables, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &brnf_sysctl_call_tables, }, { .ctl_name = NET_BRIDGE_NF_FILTER_VLAN_TAGGED, .procname = "bridge-nf-filter-vlan-tagged", .data = &brnf_filter_vlan_tagged, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &brnf_sysctl_call_tables, }, { .ctl_name = 0 } }; static ctl_table brnf_bridge_table[] = { { .ctl_name = NET_BRIDGE, .procname = "bridge", .mode = 0555, .child = brnf_table, }, { .ctl_name = 0 } }; static ctl_table brnf_net_table[] = { { .ctl_name = CTL_NET, .procname = "net", .mode = 0555, .child = brnf_bridge_table, }, { .ctl_name = 0 } }; #endif int br_netfilter_init(void) { int i; for (i = 0; i < ARRAY_SIZE(br_nf_ops); i++) { int ret; if ((ret = nf_register_hook(&br_nf_ops[i])) >= 0) continue; while (i--) nf_unregister_hook(&br_nf_ops[i]); return ret; } #ifdef CONFIG_SYSCTL brnf_sysctl_header = register_sysctl_table(brnf_net_table, 0); if (brnf_sysctl_header == NULL) { printk(KERN_WARNING "br_netfilter: can't register to sysctl.\n"); for (i = 0; i < ARRAY_SIZE(br_nf_ops); i++) nf_unregister_hook(&br_nf_ops[i]); return -EFAULT; } #endif printk(KERN_NOTICE "Bridge firewalling registered\n"); return 0; } void br_netfilter_fini(void) { int i; for (i = ARRAY_SIZE(br_nf_ops) - 1; i >= 0; i--) nf_unregister_hook(&br_nf_ops[i]); #ifdef CONFIG_SYSCTL unregister_sysctl_table(brnf_sysctl_header); #endif }
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