/* * Handle firewalling * Linux ethernet bridge * * Authors: * Lennert Buytenhek * Bart De Schuymer * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. * * Lennert dedicates this file to Kerstin Wurdinger. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if IS_ENABLED(CONFIG_NF_CONNTRACK) #include #endif #include #include "br_private.h" #ifdef CONFIG_SYSCTL #include #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; }; static DEFINE_PER_CPU(struct brnf_frag_data, brnf_frag_data_storage); #endif static struct nf_bridge_info *nf_bridge_info_get(const struct sk_buff *skb) { return skb->nf_bridge; } 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 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_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; } /* 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) { 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; } static 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; } } /* 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 sock *sk, struct sk_buff *skb) { struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); struct rtable *rt; if (nf_bridge->pkt_otherhost) { skb->pkt_type = PACKET_OTHERHOST; nf_bridge->pkt_otherhost = false; } 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, sk, 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 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 bool dnat_took_place(const struct sk_buff *skb) { #if IS_ENABLED(CONFIG_NF_CONNTRACK) enum ip_conntrack_info ctinfo; struct nf_conn *ct; ct = nf_ct_get(skb, &ctinfo); if (!ct || nf_ct_is_untracked(ct)) return false; return test_bit(IPS_DST_NAT_BIT, &ct->status); #else return false; #endif } /* 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 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; int frag_max_size; frag_max_size = IPCB(skb)->frag_max_size; BR_INPUT_SKB_CB(skb)->frag_max_size = 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 (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, 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 */ static 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; } /* 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_PAD1: 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(const struct nf_hook_ops *ops, struct sk_buff *skb, const struct nf_hook_state *state) { 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, state->sk, 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(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; __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_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; 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)) { int frag_max_size; if (skb->protocol == htons(ETH_P_IP)) { frag_max_size = IPCB(skb)->frag_max_size; BR_INPUT_SKB_CB(skb)->frag_max_size = 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) { int frag_max = BR_INPUT_SKB_CB(skb)->frag_max_size; if (br_parse_ip_options(skb)) return NF_DROP; IPCB(skb)->frag_max_size = frag_max; } 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) 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; } skb_copy_to_linear_data_offset(skb, -data->size, data->mac, data->size); __skb_push(skb, data->encap_size); return br_dev_queue_push_xmit(sk, skb); } static int br_nf_dev_queue_xmit(struct sock *sk, struct sk_buff *skb) { int ret; int frag_max_size; unsigned int mtu_reserved; if (skb_is_gso(skb) || skb->protocol != htons(ETH_P_IP)) return br_dev_queue_push_xmit(sk, skb); mtu_reserved = nf_bridge_mtu_reduction(skb); /* This is wrong! We should preserve the original fragment * boundaries by preserving frag_list rather than refragmenting. */ if (skb->len + mtu_reserved > skb->dev->mtu) { struct brnf_frag_data *data; frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size; if (br_parse_ip_options(skb)) /* Drop invalid packet */ return NF_DROP; IPCB(skb)->frag_max_size = 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); ret = ip_fragment(sk, skb, br_nf_push_frag_xmit); } else { ret = br_dev_queue_push_xmit(sk, skb); } return ret; } #else static int br_nf_dev_queue_xmit(struct sock *sk, struct sk_buff *skb) { return br_dev_queue_push_xmit(sk, skb); } #endif /* 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; 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 "); MODULE_AUTHOR("Bart De Schuymer "); MODULE_DESCRIPTION("Linux ethernet netfilter firewall bridge");