diff options
Diffstat (limited to 'net/bridge/br_netfilter.c')
-rw-r--r-- | net/bridge/br_netfilter.c | 1037 |
1 files changed, 1037 insertions, 0 deletions
diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c new file mode 100644 index 00000000..3dc7f544 --- /dev/null +++ b/net/bridge/br_netfilter.c @@ -0,0 +1,1037 @@ +/* + * Handle firewalling + * Linux ethernet bridge + * + * Authors: + * Lennert Buytenhek <buytenh@gnu.org> + * Bart De Schuymer <bdschuym@pandora.be> + * + * 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/slab.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/if_pppox.h> +#include <linux/ppp_defs.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 <linux/inetdevice.h> + +#include <net/ip.h> +#include <net/ipv6.h> +#include <net/route.h> + +#include <asm/uaccess.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) = 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 = 0; +static int brnf_filter_pppoe_tagged __read_mostly = 0; +#else +#define brnf_call_iptables 1 +#define brnf_call_ip6tables 1 +#define brnf_call_arptables 1 +#define brnf_filter_vlan_tagged 0 +#define brnf_filter_pppoe_tagged 0 +#endif + +static inline __be16 vlan_proto(const struct sk_buff *skb) +{ + if (vlan_tx_tag_present(skb)) + return skb->protocol; + else if (skb->protocol == htons(ETH_P_8021Q)) + return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto; + else + return 0; +} + +#define IS_VLAN_IP(skb) \ + (vlan_proto(skb) == htons(ETH_P_IP) && \ + brnf_filter_vlan_tagged) + +#define IS_VLAN_IPV6(skb) \ + (vlan_proto(skb) == htons(ETH_P_IPV6) && \ + brnf_filter_vlan_tagged) + +#define IS_VLAN_ARP(skb) \ + (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) + +static void fake_update_pmtu(struct dst_entry *dst, u32 mtu) +{ +} + +static u32 *fake_cow_metrics(struct dst_entry *dst, unsigned long old) +{ + return NULL; +} + +static struct dst_ops fake_dst_ops = { + .family = AF_INET, + .protocol = cpu_to_be16(ETH_P_IP), + .update_pmtu = fake_update_pmtu, + .cow_metrics = fake_cow_metrics, +}; + +/* + * 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. + */ +static const u32 br_dst_default_metrics[RTAX_MAX] = { + [RTAX_MTU - 1] = 1500, +}; + +void br_netfilter_rtable_init(struct net_bridge *br) +{ + struct rtable *rt = &br->fake_rtable; + + atomic_set(&rt->dst.__refcnt, 1); + rt->dst.dev = br->dev; + rt->dst.path = &rt->dst; + dst_init_metrics(&rt->dst, br_dst_default_metrics, true); + rt->dst.flags = DST_NOXFRM; + rt->dst.ops = &fake_dst_ops; +} + +static inline struct rtable *bridge_parent_rtable(const struct net_device *dev) +{ + struct net_bridge_port *port; + + port = br_port_get_rcu(dev); + return port ? &port->br->fake_rtable : NULL; +} + +static inline struct net_device *bridge_parent(const struct net_device *dev) +{ + struct net_bridge_port *port; + + port = br_port_get_rcu(dev); + 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); +} + +static inline void nf_bridge_update_protocol(struct sk_buff *skb) +{ + if (skb->nf_bridge->mask & BRNF_8021Q) + skb->protocol = htons(ETH_P_8021Q); + else if (skb->nf_bridge->mask & BRNF_PPPoE) + skb->protocol = htons(ETH_P_PPP_SES); +} + +/* When handing a packet over to the IP layer + * check whether we have a skb that is in the + * expected format + */ + +static int br_parse_ip_options(struct sk_buff *skb) +{ + struct ip_options *opt; + const struct iphdr *iph; + struct net_device *dev = skb->dev; + u32 len; + + iph = ip_hdr(skb); + opt = &(IPCB(skb)->opt); + + /* Basic sanity checks */ + if (iph->ihl < 5 || iph->version != 4) + goto inhdr_error; + + if (!pskb_may_pull(skb, iph->ihl*4)) + goto inhdr_error; + + iph = ip_hdr(skb); + if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl))) + goto inhdr_error; + + len = ntohs(iph->tot_len); + if (skb->len < len) { + IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS); + goto drop; + } else if (len < (iph->ihl*4)) + goto inhdr_error; + + if (pskb_trim_rcsum(skb, len)) { + IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS); + goto drop; + } + + memset(IPCB(skb), 0, sizeof(struct inet_skb_parm)); + if (iph->ihl == 5) + return 0; + + opt->optlen = iph->ihl*4 - sizeof(struct iphdr); + if (ip_options_compile(dev_net(dev), opt, skb)) + goto inhdr_error; + + /* Check correct handling of SRR option */ + if (unlikely(opt->srr)) { + struct in_device *in_dev = __in_dev_get_rcu(dev); + if (in_dev && !IN_DEV_SOURCE_ROUTE(in_dev)) + goto drop; + + if (ip_options_rcv_srr(skb)) + goto drop; + } + + return 0; + +inhdr_error: + IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS); +drop: + return -1; +} + +/* Fill in the header for fragmented IP packets handled by + * the IPv4 connection tracking code. + */ +int nf_bridge_copy_header(struct sk_buff *skb) +{ + int err; + unsigned int header_size; + + nf_bridge_update_protocol(skb); + 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; + struct rtable *rt; + + 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; + + rt = bridge_parent_rtable(nf_bridge->physindev); + if (!rt) { + kfree_skb(skb); + return 0; + } + skb_dst_set_noref(skb, &rt->dst); + + skb->dev = nf_bridge->physindev; + nf_bridge_update_protocol(skb); + nf_bridge_push_encap_header(skb); + NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, + br_handle_frame_finish, 1); + + return 0; +} + +/* Obtain the correct destination MAC address, while preserving the original + * source MAC address. If we already know this address, we just copy it. If we + * don't, we use the neighbour framework to find out. In both cases, we make + * sure that br_handle_frame_finish() is called afterwards. + */ +static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb) +{ + struct nf_bridge_info *nf_bridge = skb->nf_bridge; + struct neighbour *neigh; + struct dst_entry *dst; + + skb->dev = bridge_parent(skb->dev); + if (!skb->dev) + goto free_skb; + dst = skb_dst(skb); + neigh = dst_get_neighbour(dst); + if (dst->hh) { + neigh_hh_bridge(dst->hh, skb); + skb->dev = nf_bridge->physindev; + return br_handle_frame_finish(skb); + } else if (neigh) { + /* the neighbour function below overwrites the complete + * MAC header, so we save the Ethernet source address and + * protocol number. */ + skb_copy_from_linear_data_offset(skb, -(ETH_HLEN-ETH_ALEN), skb->nf_bridge->data, ETH_HLEN-ETH_ALEN); + /* tell br_dev_xmit to continue with forwarding */ + nf_bridge->mask |= BRNF_BRIDGED_DNAT; + return neigh->output(skb); + } +free_skb: + kfree_skb(skb); + return 0; +} + +/* This requires some explaining. If DNAT has taken place, + * we will need to fix up the destination Ethernet address. + * + * 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's first consider the case that ip_route_input() succeeds: + * + * If the output device equals the logical bridge device the packet + * came in on, we can consider this bridging. The corresponding MAC + * address will be obtained in br_nf_pre_routing_finish_bridge. + * 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's 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. + * If IP forwarding is disabled, ip_route_input() will fail, while + * ip_route_output_key() can 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 enabled. If the output device equals the logical bridge + * device, we proceed as if ip_route_input() succeeded. If it differs from the + * logical bridge port or if ip_route_output_key() fails we drop the packet. + */ +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; + struct rtable *rt; + 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 in_device *in_dev = __in_dev_get_rcu(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; + + rt = ip_route_output(dev_net(dev), iph->daddr, 0, + RT_TOS(iph->tos), 0); + if (!IS_ERR(rt)) { + /* - Bridged-and-DNAT'ed traffic doesn't + * require ip_forwarding. */ + if (rt->dst.dev == dev) { + skb_dst_set(skb, &rt->dst); + goto bridged_dnat; + } + ip_rt_put(rt); + } +free_skb: + kfree_skb(skb); + return 0; + } else { + if (skb_dst(skb)->dev == dev) { +bridged_dnat: + skb->dev = nf_bridge->physindev; + nf_bridge_update_protocol(skb); + nf_bridge_push_encap_header(skb); + NF_HOOK_THRESH(NFPROTO_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 { + rt = bridge_parent_rtable(nf_bridge->physindev); + if (!rt) { + kfree_skb(skb); + return 0; + } + skb_dst_set_noref(skb, &rt->dst); + } + + skb->dev = nf_bridge->physindev; + nf_bridge_update_protocol(skb); + nf_bridge_push_encap_header(skb); + NF_HOOK_THRESH(NFPROTO_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); + if (skb->protocol == htons(ETH_P_8021Q)) + nf_bridge->mask |= BRNF_8021Q; + else if (skb->protocol == htons(ETH_P_PPP_SES)) + nf_bridge->mask |= BRNF_PPPoE; + + 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 *)) +{ + const struct ipv6hdr *hdr; + u32 pkt_len; + + if (skb->len < sizeof(struct ipv6hdr)) + return NF_DROP; + + if (!pskb_may_pull(skb, sizeof(struct ipv6hdr))) + return NF_DROP; + + hdr = ipv6_hdr(skb); + + if (hdr->version != 6) + return NF_DROP; + + pkt_len = ntohs(hdr->payload_len); + + if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) { + if (pkt_len + sizeof(struct ipv6hdr) > skb->len) + return NF_DROP; + if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) + return NF_DROP; + } + if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb)) + return NF_DROP; + + nf_bridge_put(skb->nf_bridge); + if (!nf_bridge_alloc(skb)) + return NF_DROP; + if (!setup_pre_routing(skb)) + return NF_DROP; + + skb->protocol = htons(ETH_P_IPV6); + NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, skb->dev, NULL, + br_nf_pre_routing_finish_ipv6); + + return NF_STOLEN; +} + +/* 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 net_bridge_port *p; + struct net_bridge *br; + __u32 len = nf_bridge_encap_header_len(skb); + + if (unlikely(!pskb_may_pull(skb, len))) + return NF_DROP; + + p = br_port_get_rcu(in); + if (p == NULL) + return NF_DROP; + br = p->br; + + if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) || + IS_PPPOE_IPV6(skb)) { + if (!brnf_call_ip6tables && !br->nf_call_ip6tables) + return NF_ACCEPT; + + nf_bridge_pull_encap_header_rcsum(skb); + return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn); + } + + if (!brnf_call_iptables && !br->nf_call_iptables) + return NF_ACCEPT; + + 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 (br_parse_ip_options(skb)) + return NF_DROP; + + 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); + skb->protocol = htons(ETH_P_IP); + + NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL, + br_nf_pre_routing_finish); + + return NF_STOLEN; +} + + +/* 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 *)) +{ + struct rtable *rt = skb_rtable(skb); + + if (rt && rt == bridge_parent_rtable(in)) + skb_dst_drop(skb); + + 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; + } + nf_bridge_update_protocol(skb); + } else { + in = *((struct net_device **)(skb->cb)); + } + nf_bridge_push_encap_header(skb); + + NF_HOOK_THRESH(NFPROTO_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; + u_int8_t 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 if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) || + IS_PPPOE_IPV6(skb)) + pf = PF_INET6; + else + return NF_ACCEPT; + + 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; + } + + if (pf == PF_INET && br_parse_ip_options(skb)) + return NF_DROP; + + /* The physdev module checks on this */ + nf_bridge->mask |= BRNF_BRIDGED; + nf_bridge->physoutdev = skb->dev; + if (pf == PF_INET) + skb->protocol = htons(ETH_P_IP); + else + skb->protocol = htons(ETH_P_IPV6); + + 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_bridge_port *p; + struct net_bridge *br; + struct net_device **d = (struct net_device **)(skb->cb); + + p = br_port_get_rcu(out); + if (p == NULL) + return NF_ACCEPT; + br = p->br; + + if (!brnf_call_arptables && !br->nf_call_arptables) + return NF_ACCEPT; + + 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(NFPROTO_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in, + (struct net_device *)out, br_nf_forward_finish); + + return NF_STOLEN; +} + +#if defined(CONFIG_NF_CONNTRACK_IPV4) || defined(CONFIG_NF_CONNTRACK_IPV4_MODULE) +static int br_nf_dev_queue_xmit(struct sk_buff *skb) +{ + int ret; + + if (skb->nfct != NULL && skb->protocol == htons(ETH_P_IP) && + skb->len + nf_bridge_mtu_reduction(skb) > skb->dev->mtu && + !skb_is_gso(skb)) { + if (br_parse_ip_options(skb)) + /* Drop invalid packet */ + return NF_DROP; + ret = ip_fragment(skb, br_dev_queue_push_xmit); + } else + ret = br_dev_queue_push_xmit(skb); + + return ret; +} +#else +static int br_nf_dev_queue_xmit(struct sk_buff *skb) +{ + return br_dev_queue_push_xmit(skb); +} +#endif + +/* 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); + u_int8_t pf; + + if (!nf_bridge || !(nf_bridge->mask & BRNF_BRIDGED)) + 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 if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) || + IS_PPPOE_IPV6(skb)) + pf = PF_INET6; + else + return NF_ACCEPT; + + /* 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); + if (pf == PF_INET) + skb->protocol = htons(ETH_P_IP); + else + skb->protocol = htons(ETH_P_IPV6); + + NF_HOOK(pf, NF_INET_POST_ROUTING, skb, NULL, realoutdev, + br_nf_dev_queue_xmit); + + return NF_STOLEN; +} + +/* 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_post_routing, we need (prio = NF_BR_PRI_LAST), because + * br_dev_queue_push_xmit is called afterwards */ +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_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, + void __user * buffer, size_t * lenp, loff_t * ppos) +{ + int ret; + + ret = proc_dointvec(ctl, write, 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, + }, + { } +}; + +static struct ctl_path brnf_path[] = { + { .procname = "net", }, + { .procname = "bridge", }, + { } +}; +#endif + +int __init br_netfilter_init(void) +{ + int ret; + + ret = dst_entries_init(&fake_dst_ops); + if (ret < 0) + return ret; + + ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops)); + if (ret < 0) { + dst_entries_destroy(&fake_dst_ops); + 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)); + dst_entries_destroy(&fake_dst_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 + dst_entries_destroy(&fake_dst_ops); +} |