diff options
Diffstat (limited to 'net/bridge/br_netfilter.c')
| -rw-r--r-- | net/bridge/br_netfilter.c | 1087 |
1 files changed, 1087 insertions, 0 deletions
diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c new file mode 100644 index 000000000000..be03d3ad2648 --- /dev/null +++ b/net/bridge/br_netfilter.c @@ -0,0 +1,1087 @@ +/* + * 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_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 <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) + +#define has_bridge_parent(device) ((device)->br_port != NULL) +#define bridge_parent(device) ((device)->br_port->br->dev) + +#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}, + } + }, + .rt_flags = 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; + +#ifdef CONFIG_NETFILTER_DEBUG + skb->nf_debug ^= (1 << NF_BR_PRE_ROUTING); +#endif + + 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) +{ +#ifdef CONFIG_NETFILTER_DEBUG + skb->nf_debug |= (1 << NF_BR_PRE_ROUTING) | (1 << NF_BR_FORWARD); +#endif + + 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->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; + +#ifdef CONFIG_NETFILTER_DEBUG + skb->nf_debug ^= (1 << NF_BR_PRE_ROUTING); +#endif + + 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. */ + if (((struct dst_entry *)rt)->dev == dev) { + 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 void 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); +} + +/* 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 = 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 > skb->len - sizeof(struct ipv6hdr)) + goto bad; + if (pkt_len + sizeof(struct ipv6hdr) < skb->len) { + if (__pskb_trim(skb, + pkt_len + sizeof(struct ipv6hdr))) + goto bad; + if (skb->ip_summed == CHECKSUM_HW) + skb->ip_summed = CHECKSUM_NONE; + } + 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; + +#ifdef CONFIG_NETFILTER_DEBUG + skb->nf_debug ^= (1 << NF_IP6_PRE_ROUTING); +#endif + if ((nf_bridge = nf_bridge_alloc(skb)) == NULL) + return NF_DROP; + setup_pre_routing(skb); + + 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)) { + skb_pull(skb, 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)) { + skb_pull(skb, 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; + } + +#ifdef CONFIG_NETFILTER_DEBUG + skb->nf_debug ^= (1 << NF_IP_PRE_ROUTING); +#endif + if ((nf_bridge = nf_bridge_alloc(skb)) == NULL) + return NF_DROP; + setup_pre_routing(skb); + 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); + +#ifdef CONFIG_NETFILTER_DEBUG + skb->nf_debug ^= (1 << NF_BR_FORWARD); +#endif + + 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); + 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; + + if (skb->protocol == __constant_htons(ETH_P_8021Q)) { + skb_pull(*pskb, VLAN_HLEN); + (*pskb)->nh.raw += VLAN_HLEN; + } + +#ifdef CONFIG_NETFILTER_DEBUG + skb->nf_debug ^= (1 << NF_BR_FORWARD); +#endif + 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), + bridge_parent(out), 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; + } + +#ifdef CONFIG_NETFILTER_DEBUG + skb->nf_debug ^= (1 << NF_BR_FORWARD); +#endif + + 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) +{ +#ifdef CONFIG_NETFILTER_DEBUG + skb->nf_debug &= ~(1 << NF_BR_LOCAL_OUT); +#endif + 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 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) && + has_bridge_parent(realindev)) + realindev = bridge_parent(realindev); + + NF_HOOK_THRESH(pf, NF_IP_FORWARD, skb, realindev, + realoutdev, br_nf_local_out_finish, + NF_IP_PRI_BRIDGE_SABOTAGE_FORWARD + 1); + } else { +#ifdef CONFIG_NETFILTER_DEBUG + skb->nf_debug ^= (1 << NF_IP_LOCAL_OUT); +#endif + + 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 (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; + } + + skb->nf_debug ^= (1 << NF_IP_POST_ROUTING); +#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 (has_bridge_parent(skb->dev)) + printk("[%s]", bridge_parent(skb->dev)->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 +} |