diff options
Diffstat (limited to 'net/bridge/br_netfilter_hooks.c')
| -rw-r--r-- | net/bridge/br_netfilter_hooks.c | 1052 |
1 files changed, 1052 insertions, 0 deletions
diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c new file mode 100644 index 000000000000..d89f4fac0bc5 --- /dev/null +++ b/net/bridge/br_netfilter_hooks.c @@ -0,0 +1,1052 @@ +/* + * 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/addrconf.h> +#include <net/route.h> +#include <net/netfilter/br_netfilter.h> + +#include <asm/uaccess.h> +#include "br_private.h" +#ifdef CONFIG_SYSCTL +#include <linux/sysctl.h> +#endif + +#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; +static int brnf_pass_vlan_indev __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 +#define brnf_pass_vlan_indev 0 +#endif + +#define IS_IP(skb) \ + (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IP)) + +#define IS_IPV6(skb) \ + (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IPV6)) + +#define IS_ARP(skb) \ + (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_ARP)) + +static inline __be16 vlan_proto(const struct sk_buff *skb) +{ + if (skb_vlan_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) + +/* largest possible L2 header, see br_nf_dev_queue_xmit() */ +#define NF_BRIDGE_MAX_MAC_HEADER_LENGTH (PPPOE_SES_HLEN + ETH_HLEN) + +#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4) +struct brnf_frag_data { + char mac[NF_BRIDGE_MAX_MAC_HEADER_LENGTH]; + u8 encap_size; + u8 size; + u16 vlan_tci; + __be16 vlan_proto; +}; + +static DEFINE_PER_CPU(struct brnf_frag_data, brnf_frag_data_storage); +#endif + +static void nf_bridge_info_free(struct sk_buff *skb) +{ + if (skb->nf_bridge) { + nf_bridge_put(skb->nf_bridge); + skb->nf_bridge = 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_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; +} + +unsigned int nf_bridge_encap_header_len(const struct sk_buff *skb) +{ + switch (skb->protocol) { + case __cpu_to_be16(ETH_P_8021Q): + return VLAN_HLEN; + case __cpu_to_be16(ETH_P_PPP_SES): + return PPPOE_SES_HLEN; + default: + return 0; + } +} + +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; +} + +/* When handing a packet over to the IP layer + * check whether we have a skb that is in the + * expected format + */ + +static int br_validate_ipv4(struct sk_buff *skb) +{ + const struct iphdr *iph; + struct net_device *dev = skb->dev; + u32 len; + + if (!pskb_may_pull(skb, sizeof(struct iphdr))) + goto inhdr_error; + + iph = ip_hdr(skb); + + /* 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)); + /* We should really parse IP options here but until + * somebody who actually uses IP options complains to + * us we'll just silently ignore the options because + * we're lazy! + */ + return 0; + +inhdr_error: + IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS); +drop: + return -1; +} + +void nf_bridge_update_protocol(struct sk_buff *skb) +{ + switch (skb->nf_bridge->orig_proto) { + case BRNF_PROTO_8021Q: + skb->protocol = htons(ETH_P_8021Q); + break; + case BRNF_PROTO_PPPOE: + skb->protocol = htons(ETH_P_PPP_SES); + break; + case BRNF_PROTO_UNCHANGED: + break; + } +} + +/* 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. + */ +int br_nf_pre_routing_finish_bridge(struct sock *sk, struct sk_buff *skb) +{ + 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_neigh_lookup_skb(dst, skb); + if (neigh) { + struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); + int ret; + + if (neigh->hh.hh_len) { + neigh_hh_bridge(&neigh->hh, skb); + skb->dev = nf_bridge->physindev; + ret = br_handle_frame_finish(sk, skb); + } else { + /* 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), + nf_bridge->neigh_header, + ETH_HLEN-ETH_ALEN); + /* tell br_dev_xmit to continue with forwarding */ + nf_bridge->mask |= BRNF_BRIDGED_DNAT; + /* FIXME Need to refragment */ + ret = neigh->output(neigh, skb); + } + neigh_release(neigh); + return ret; + } +free_skb: + kfree_skb(skb); + return 0; +} + +static inline bool +br_nf_ipv4_daddr_was_changed(const struct sk_buff *skb, + const struct nf_bridge_info *nf_bridge) +{ + return ip_hdr(skb)->daddr != nf_bridge->ipv4_daddr; +} + +/* This requires some explaining. If DNAT has taken place, + * we will need to fix up the destination Ethernet address. + * This is also true when SNAT takes place (for the reply direction). + * + * 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 sock *sk, struct sk_buff *skb) +{ + struct net_device *dev = skb->dev; + struct iphdr *iph = ip_hdr(skb); + struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); + struct rtable *rt; + int err; + + nf_bridge->frag_max_size = IPCB(skb)->frag_max_size; + + if (nf_bridge->pkt_otherhost) { + skb->pkt_type = PACKET_OTHERHOST; + nf_bridge->pkt_otherhost = false; + } + nf_bridge->mask &= ~BRNF_NF_BRIDGE_PREROUTING; + if (br_nf_ipv4_daddr_was_changed(skb, nf_bridge)) { + 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, + sk, skb, skb->dev, NULL, + br_nf_pre_routing_finish_bridge, + 1); + return 0; + } + ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr); + 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, sk, skb, + skb->dev, NULL, + br_handle_frame_finish, 1); + + return 0; +} + +static struct net_device *brnf_get_logical_dev(struct sk_buff *skb, const struct net_device *dev) +{ + struct net_device *vlan, *br; + + br = bridge_parent(dev); + if (brnf_pass_vlan_indev == 0 || !skb_vlan_tag_present(skb)) + return br; + + vlan = __vlan_find_dev_deep_rcu(br, skb->vlan_proto, + skb_vlan_tag_get(skb) & VLAN_VID_MASK); + + return vlan ? vlan : br; +} + +/* Some common code for IPv4/IPv6 */ +struct net_device *setup_pre_routing(struct sk_buff *skb) +{ + struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); + + if (skb->pkt_type == PACKET_OTHERHOST) { + skb->pkt_type = PACKET_HOST; + nf_bridge->pkt_otherhost = true; + } + + nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING; + nf_bridge->physindev = skb->dev; + skb->dev = brnf_get_logical_dev(skb, skb->dev); + + if (skb->protocol == htons(ETH_P_8021Q)) + nf_bridge->orig_proto = BRNF_PROTO_8021Q; + else if (skb->protocol == htons(ETH_P_PPP_SES)) + nf_bridge->orig_proto = BRNF_PROTO_PPPOE; + + /* Must drop socket now because of tproxy. */ + skb_orphan(skb); + return skb->dev; +} + +/* 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(const struct nf_hook_ops *ops, + struct sk_buff *skb, + const struct nf_hook_state *state) +{ + struct nf_bridge_info *nf_bridge; + 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(state->in); + if (p == NULL) + return NF_DROP; + br = p->br; + + if (IS_IPV6(skb) || 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(ops, skb, state); + } + + if (!brnf_call_iptables && !br->nf_call_iptables) + return NF_ACCEPT; + + if (!IS_IP(skb) && !IS_VLAN_IP(skb) && !IS_PPPOE_IP(skb)) + return NF_ACCEPT; + + nf_bridge_pull_encap_header_rcsum(skb); + + if (br_validate_ipv4(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; + + nf_bridge = nf_bridge_info_get(skb); + nf_bridge->ipv4_daddr = ip_hdr(skb)->daddr; + + skb->protocol = htons(ETH_P_IP); + + NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, state->sk, 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(const struct nf_hook_ops *ops, + struct sk_buff *skb, + const struct nf_hook_state *state) +{ + br_drop_fake_rtable(skb); + return NF_ACCEPT; +} + +/* PF_BRIDGE/FORWARD *************************************************/ +static int br_nf_forward_finish(struct sock *sk, struct sk_buff *skb) +{ + struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); + struct net_device *in; + + if (!IS_ARP(skb) && !IS_VLAN_ARP(skb)) { + + if (skb->protocol == htons(ETH_P_IP)) + nf_bridge->frag_max_size = IPCB(skb)->frag_max_size; + + if (skb->protocol == htons(ETH_P_IPV6)) + nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size; + + in = nf_bridge->physindev; + if (nf_bridge->pkt_otherhost) { + skb->pkt_type = PACKET_OTHERHOST; + nf_bridge->pkt_otherhost = false; + } + 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, sk, 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(const struct nf_hook_ops *ops, + struct sk_buff *skb, + const struct nf_hook_state *state) +{ + 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; + + nf_bridge = nf_bridge_info_get(skb); + if (!nf_bridge) + return NF_DROP; + + parent = bridge_parent(state->out); + if (!parent) + return NF_DROP; + + if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb)) + pf = NFPROTO_IPV4; + else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb)) + pf = NFPROTO_IPV6; + else + return NF_ACCEPT; + + nf_bridge_pull_encap_header(skb); + + if (skb->pkt_type == PACKET_OTHERHOST) { + skb->pkt_type = PACKET_HOST; + nf_bridge->pkt_otherhost = true; + } + + if (pf == NFPROTO_IPV4) { + if (br_validate_ipv4(skb)) + return NF_DROP; + IPCB(skb)->frag_max_size = nf_bridge->frag_max_size; + } + + if (pf == NFPROTO_IPV6) { + if (br_validate_ipv6(skb)) + return NF_DROP; + IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size; + } + + nf_bridge->physoutdev = skb->dev; + if (pf == NFPROTO_IPV4) + skb->protocol = htons(ETH_P_IP); + else + skb->protocol = htons(ETH_P_IPV6); + + NF_HOOK(pf, NF_INET_FORWARD, NULL, skb, + brnf_get_logical_dev(skb, state->in), + parent, br_nf_forward_finish); + + return NF_STOLEN; +} + +static unsigned int br_nf_forward_arp(const struct nf_hook_ops *ops, + struct sk_buff *skb, + const struct nf_hook_state *state) +{ + struct net_bridge_port *p; + struct net_bridge *br; + struct net_device **d = (struct net_device **)(skb->cb); + + p = br_port_get_rcu(state->out); + if (p == NULL) + return NF_ACCEPT; + br = p->br; + + if (!brnf_call_arptables && !br->nf_call_arptables) + return NF_ACCEPT; + + if (!IS_ARP(skb)) { + 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 = state->in; + NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, state->sk, skb, + state->in, state->out, br_nf_forward_finish); + + return NF_STOLEN; +} + +#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4) || IS_ENABLED(CONFIG_NF_DEFRAG_IPV6) +static int br_nf_push_frag_xmit(struct sock *sk, struct sk_buff *skb) +{ + struct brnf_frag_data *data; + int err; + + data = this_cpu_ptr(&brnf_frag_data_storage); + err = skb_cow_head(skb, data->size); + + if (err) { + kfree_skb(skb); + return 0; + } + + if (data->vlan_tci) { + skb->vlan_tci = data->vlan_tci; + skb->vlan_proto = data->vlan_proto; + } + + skb_copy_to_linear_data_offset(skb, -data->size, data->mac, data->size); + __skb_push(skb, data->encap_size); + + nf_bridge_info_free(skb); + return br_dev_queue_push_xmit(sk, skb); +} +#endif + +static int br_nf_ip_fragment(struct sock *sk, struct sk_buff *skb, + int (*output)(struct sock *, struct sk_buff *)) +{ + unsigned int mtu = ip_skb_dst_mtu(skb); + struct iphdr *iph = ip_hdr(skb); + struct rtable *rt = skb_rtable(skb); + struct net_device *dev = rt->dst.dev; + + if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) || + (IPCB(skb)->frag_max_size && + IPCB(skb)->frag_max_size > mtu))) { + IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); + kfree_skb(skb); + return -EMSGSIZE; + } + + return ip_do_fragment(sk, skb, output); +} + +static unsigned int nf_bridge_mtu_reduction(const struct sk_buff *skb) +{ + if (skb->nf_bridge->orig_proto == BRNF_PROTO_PPPOE) + return PPPOE_SES_HLEN; + return 0; +} + +static int br_nf_dev_queue_xmit(struct sock *sk, struct sk_buff *skb) +{ + struct nf_bridge_info *nf_bridge; + unsigned int mtu_reserved; + + mtu_reserved = nf_bridge_mtu_reduction(skb); + + if (skb_is_gso(skb) || skb->len + mtu_reserved <= skb->dev->mtu) { + nf_bridge_info_free(skb); + return br_dev_queue_push_xmit(sk, skb); + } + + nf_bridge = nf_bridge_info_get(skb); + +#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4) + /* This is wrong! We should preserve the original fragment + * boundaries by preserving frag_list rather than refragmenting. + */ + if (skb->protocol == htons(ETH_P_IP)) { + struct brnf_frag_data *data; + + if (br_validate_ipv4(skb)) + return NF_DROP; + + IPCB(skb)->frag_max_size = nf_bridge->frag_max_size; + + nf_bridge_update_protocol(skb); + + data = this_cpu_ptr(&brnf_frag_data_storage); + + data->vlan_tci = skb->vlan_tci; + data->vlan_proto = skb->vlan_proto; + data->encap_size = nf_bridge_encap_header_len(skb); + data->size = ETH_HLEN + data->encap_size; + + skb_copy_from_linear_data_offset(skb, -data->size, data->mac, + data->size); + + return br_nf_ip_fragment(sk, skb, br_nf_push_frag_xmit); + } +#endif +#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6) + if (skb->protocol == htons(ETH_P_IPV6)) { + const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops(); + struct brnf_frag_data *data; + + if (br_validate_ipv6(skb)) + return NF_DROP; + + IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size; + + nf_bridge_update_protocol(skb); + + data = this_cpu_ptr(&brnf_frag_data_storage); + data->encap_size = nf_bridge_encap_header_len(skb); + data->size = ETH_HLEN + data->encap_size; + + skb_copy_from_linear_data_offset(skb, -data->size, data->mac, + data->size); + + if (v6ops) + return v6ops->fragment(sk, skb, br_nf_push_frag_xmit); + else + return -EMSGSIZE; + } +#endif + nf_bridge_info_free(skb); + return br_dev_queue_push_xmit(sk, skb); +} + +/* PF_BRIDGE/POST_ROUTING ********************************************/ +static unsigned int br_nf_post_routing(const struct nf_hook_ops *ops, + struct sk_buff *skb, + const struct nf_hook_state *state) +{ + struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); + struct net_device *realoutdev = bridge_parent(skb->dev); + u_int8_t pf; + + /* if nf_bridge is set, but ->physoutdev is NULL, this packet came in + * on a bridge, but was delivered locally and is now being routed: + * + * POST_ROUTING was already invoked from the ip stack. + */ + if (!nf_bridge || !nf_bridge->physoutdev) + return NF_ACCEPT; + + if (!realoutdev) + return NF_DROP; + + if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb)) + pf = NFPROTO_IPV4; + else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb)) + pf = NFPROTO_IPV6; + 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->pkt_otherhost = true; + } + + nf_bridge_pull_encap_header(skb); + if (pf == NFPROTO_IPV4) + skb->protocol = htons(ETH_P_IP); + else + skb->protocol = htons(ETH_P_IPV6); + + NF_HOOK(pf, NF_INET_POST_ROUTING, state->sk, 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(const struct nf_hook_ops *ops, + struct sk_buff *skb, + const struct nf_hook_state *state) +{ + if (skb->nf_bridge && + !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) { + return NF_STOP; + } + + return NF_ACCEPT; +} + +/* This is called when br_netfilter has called into iptables/netfilter, + * and DNAT has taken place on a bridge-forwarded packet. + * + * neigh->output has created a new MAC header, with local br0 MAC + * as saddr. + * + * This restores the original MAC saddr of the bridged packet + * before invoking bridge forward logic to transmit the packet. + */ +static void br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb) +{ + struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); + + skb_pull(skb, ETH_HLEN); + nf_bridge->mask &= ~BRNF_BRIDGED_DNAT; + + BUILD_BUG_ON(sizeof(nf_bridge->neigh_header) != (ETH_HLEN - ETH_ALEN)); + + skb_copy_to_linear_data_offset(skb, -(ETH_HLEN - ETH_ALEN), + nf_bridge->neigh_header, + ETH_HLEN - ETH_ALEN); + skb->dev = nf_bridge->physindev; + + nf_bridge->physoutdev = NULL; + br_handle_frame_finish(NULL, skb); +} + +static int br_nf_dev_xmit(struct sk_buff *skb) +{ + if (skb->nf_bridge && (skb->nf_bridge->mask & BRNF_BRIDGED_DNAT)) { + br_nf_pre_routing_finish_bridge_slow(skb); + return 1; + } + return 0; +} + +static const struct nf_br_ops br_ops = { + .br_dev_xmit_hook = br_nf_dev_xmit, +}; + +void br_netfilter_enable(void) +{ +} +EXPORT_SYMBOL_GPL(br_netfilter_enable); + +/* 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 = NFPROTO_BRIDGE, + .hooknum = NF_BR_PRE_ROUTING, + .priority = NF_BR_PRI_BRNF, + }, + { + .hook = br_nf_local_in, + .owner = THIS_MODULE, + .pf = NFPROTO_BRIDGE, + .hooknum = NF_BR_LOCAL_IN, + .priority = NF_BR_PRI_BRNF, + }, + { + .hook = br_nf_forward_ip, + .owner = THIS_MODULE, + .pf = NFPROTO_BRIDGE, + .hooknum = NF_BR_FORWARD, + .priority = NF_BR_PRI_BRNF - 1, + }, + { + .hook = br_nf_forward_arp, + .owner = THIS_MODULE, + .pf = NFPROTO_BRIDGE, + .hooknum = NF_BR_FORWARD, + .priority = NF_BR_PRI_BRNF, + }, + { + .hook = br_nf_post_routing, + .owner = THIS_MODULE, + .pf = NFPROTO_BRIDGE, + .hooknum = NF_BR_POST_ROUTING, + .priority = NF_BR_PRI_LAST, + }, + { + .hook = ip_sabotage_in, + .owner = THIS_MODULE, + .pf = NFPROTO_IPV4, + .hooknum = NF_INET_PRE_ROUTING, + .priority = NF_IP_PRI_FIRST, + }, + { + .hook = ip_sabotage_in, + .owner = THIS_MODULE, + .pf = NFPROTO_IPV6, + .hooknum = NF_INET_PRE_ROUTING, + .priority = NF_IP6_PRI_FIRST, + }, +}; + +#ifdef CONFIG_SYSCTL +static +int brnf_sysctl_call_tables(struct 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 struct 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, + }, + { + .procname = "bridge-nf-pass-vlan-input-dev", + .data = &brnf_pass_vlan_indev, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = brnf_sysctl_call_tables, + }, + { } +}; +#endif + +static 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_net_sysctl(&init_net, "net/bridge", 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 + RCU_INIT_POINTER(nf_br_ops, &br_ops); + printk(KERN_NOTICE "Bridge firewalling registered\n"); + return 0; +} + +static void __exit br_netfilter_fini(void) +{ + RCU_INIT_POINTER(nf_br_ops, NULL); + nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops)); +#ifdef CONFIG_SYSCTL + unregister_net_sysctl_table(brnf_sysctl_header); +#endif +} + +module_init(br_netfilter_init); +module_exit(br_netfilter_fini); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Lennert Buytenhek <buytenh@gnu.org>"); +MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>"); +MODULE_DESCRIPTION("Linux ethernet netfilter firewall bridge"); |