// SPDX-License-Identifier: GPL-2.0-or-later /* * Handle firewalling * Linux ethernet bridge * * Authors: * Lennert Buytenhek * Bart De Schuymer * * 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 #include #include #include #include #include #include "br_private.h" #ifdef CONFIG_SYSCTL #include #endif #if IS_ENABLED(CONFIG_NF_CONNTRACK) #include #endif static unsigned int brnf_net_id __read_mostly; struct brnf_net { bool enabled; #ifdef CONFIG_SYSCTL struct ctl_table_header *ctl_hdr; #endif /* default value is 1 */ int call_iptables; int call_ip6tables; int call_arptables; /* default value is 0 */ int filter_vlan_tagged; int filter_pppoe_tagged; int pass_vlan_indev; }; #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; } static inline bool is_vlan_ip(const struct sk_buff *skb, const struct net *net) { struct brnf_net *brnet = net_generic(net, brnf_net_id); return vlan_proto(skb) == htons(ETH_P_IP) && brnet->filter_vlan_tagged; } static inline bool is_vlan_ipv6(const struct sk_buff *skb, const struct net *net) { struct brnf_net *brnet = net_generic(net, brnf_net_id); return vlan_proto(skb) == htons(ETH_P_IPV6) && brnet->filter_vlan_tagged; } static inline bool is_vlan_arp(const struct sk_buff *skb, const struct net *net) { struct brnf_net *brnet = net_generic(net, brnf_net_id); return vlan_proto(skb) == htons(ETH_P_ARP) && brnet->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))); } static inline bool is_pppoe_ip(const struct sk_buff *skb, const struct net *net) { struct brnf_net *brnet = net_generic(net, brnf_net_id); return skb->protocol == htons(ETH_P_PPP_SES) && pppoe_proto(skb) == htons(PPP_IP) && brnet->filter_pppoe_tagged; } static inline bool is_pppoe_ipv6(const struct sk_buff *skb, const struct net *net) { struct brnf_net *brnet = net_generic(net, brnf_net_id); return skb->protocol == htons(ETH_P_PPP_SES) && pppoe_proto(skb) == htons(PPP_IPV6) && brnet->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) 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); static void nf_bridge_info_free(struct sk_buff *skb) { skb_ext_del(skb, SKB_EXT_BRIDGE_NF); } 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) { return skb_ext_add(skb, SKB_EXT_BRIDGE_NF); } 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 net *net, struct sk_buff *skb) { const struct iphdr *iph; 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 csum_error; len = ntohs(iph->tot_len); if (skb->len < len) { __IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS); goto drop; } else if (len < (iph->ihl*4)) goto inhdr_error; if (pskb_trim_rcsum(skb, len)) { __IP_INC_STATS(net, 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; csum_error: __IP_INC_STATS(net, IPSTATS_MIB_CSUMERRORS); inhdr_error: __IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS); drop: return -1; } void nf_bridge_update_protocol(struct sk_buff *skb) { const struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); switch (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 net *net, 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->nud_state & NUD_CONNECTED) && neigh->hh.hh_len) { neigh_hh_bridge(&neigh->hh, skb); skb->dev = nf_bridge->physindev; ret = br_handle_frame_finish(net, 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->bridged_dnat = 1; /* 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 net *net, 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->in_prerouting = 0; 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(net, 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_drop(skb); 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); br_nf_hook_thresh(NF_BR_PRE_ROUTING, net, sk, skb, skb->dev, NULL, br_nf_pre_routing_finish_bridge); 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_drop(skb); skb_dst_set_noref(skb, &rt->dst); } skb->dev = nf_bridge->physindev; nf_bridge_update_protocol(skb); nf_bridge_push_encap_header(skb); br_nf_hook_thresh(NF_BR_PRE_ROUTING, net, sk, skb, skb->dev, NULL, br_handle_frame_finish); return 0; } static struct net_device *brnf_get_logical_dev(struct sk_buff *skb, const struct net_device *dev, const struct net *net) { struct net_device *vlan, *br; struct brnf_net *brnet = net_generic(net, brnf_net_id); br = bridge_parent(dev); if (brnet->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, const struct net *net) { 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->in_prerouting = 1; nf_bridge->physindev = skb->dev; skb->dev = brnf_get_logical_dev(skb, skb->dev, net); 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(void *priv, 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); struct brnf_net *brnet; 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; brnet = net_generic(state->net, brnf_net_id); if (IS_IPV6(skb) || is_vlan_ipv6(skb, state->net) || is_pppoe_ipv6(skb, state->net)) { if (!brnet->call_ip6tables && !br_opt_get(br, BROPT_NF_CALL_IP6TABLES)) return NF_ACCEPT; if (!ipv6_mod_enabled()) { pr_warn_once("Module ipv6 is disabled, so call_ip6tables is not supported."); return NF_DROP; } nf_bridge_pull_encap_header_rcsum(skb); return br_nf_pre_routing_ipv6(priv, skb, state); } if (!brnet->call_iptables && !br_opt_get(br, BROPT_NF_CALL_IPTABLES)) return NF_ACCEPT; if (!IS_IP(skb) && !is_vlan_ip(skb, state->net) && !is_pppoe_ip(skb, state->net)) return NF_ACCEPT; nf_bridge_pull_encap_header_rcsum(skb); if (br_validate_ipv4(state->net, skb)) return NF_DROP; if (!nf_bridge_alloc(skb)) return NF_DROP; if (!setup_pre_routing(skb, state->net)) return NF_DROP; nf_bridge = nf_bridge_info_get(skb); nf_bridge->ipv4_daddr = ip_hdr(skb)->daddr; skb->protocol = htons(ETH_P_IP); skb->transport_header = skb->network_header + ip_hdr(skb)->ihl * 4; NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, state->net, state->sk, skb, skb->dev, NULL, br_nf_pre_routing_finish); return NF_STOLEN; } #if IS_ENABLED(CONFIG_NF_CONNTRACK) /* conntracks' nf_confirm logic cannot handle cloned skbs referencing * the same nf_conn entry, which will happen for multicast (broadcast) * Frames on bridges. * * Example: * macvlan0 * br0 * ethX ethY * * ethX (or Y) receives multicast or broadcast packet containing * an IP packet, not yet in conntrack table. * * 1. skb passes through bridge and fake-ip (br_netfilter)Prerouting. * -> skb->_nfct now references a unconfirmed entry * 2. skb is broad/mcast packet. bridge now passes clones out on each bridge * interface. * 3. skb gets passed up the stack. * 4. In macvlan case, macvlan driver retains clone(s) of the mcast skb * and schedules a work queue to send them out on the lower devices. * * The clone skb->_nfct is not a copy, it is the same entry as the * original skb. The macvlan rx handler then returns RX_HANDLER_PASS. * 5. Normal conntrack hooks (in NF_INET_LOCAL_IN) confirm the orig skb. * * The Macvlan broadcast worker and normal confirm path will race. * * This race will not happen if step 2 already confirmed a clone. In that * case later steps perform skb_clone() with skb->_nfct already confirmed (in * hash table). This works fine. * * But such confirmation won't happen when eb/ip/nftables rules dropped the * packets before they reached the nf_confirm step in postrouting. * * Work around this problem by explicit confirmation of the entry at * LOCAL_IN time, before upper layer has a chance to clone the unconfirmed * entry. * */ static unsigned int br_nf_local_in(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) { struct nf_conntrack *nfct = skb_nfct(skb); const struct nf_ct_hook *ct_hook; struct nf_conn *ct; int ret; if (!nfct || skb->pkt_type == PACKET_HOST) return NF_ACCEPT; ct = container_of(nfct, struct nf_conn, ct_general); if (likely(nf_ct_is_confirmed(ct))) return NF_ACCEPT; WARN_ON_ONCE(skb_shared(skb)); WARN_ON_ONCE(refcount_read(&nfct->use) != 1); /* We can't call nf_confirm here, it would create a dependency * on nf_conntrack module. */ ct_hook = rcu_dereference(nf_ct_hook); if (!ct_hook) { skb->_nfct = 0ul; nf_conntrack_put(nfct); return NF_ACCEPT; } nf_bridge_pull_encap_header(skb); ret = ct_hook->confirm(skb); switch (ret & NF_VERDICT_MASK) { case NF_STOLEN: return NF_STOLEN; default: nf_bridge_push_encap_header(skb); break; } ct = container_of(nfct, struct nf_conn, ct_general); WARN_ON_ONCE(!nf_ct_is_confirmed(ct)); return ret; } #endif /* PF_BRIDGE/FORWARD *************************************************/ static int br_nf_forward_finish(struct net *net, 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, net)) { 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); br_nf_hook_thresh(NF_BR_FORWARD, net, sk, skb, in, skb->dev, br_forward_finish); 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(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) { struct nf_bridge_info *nf_bridge; struct net_device *parent; u_int8_t pf; nf_bridge = nf_bridge_info_get(skb); if (!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, state->net) || is_pppoe_ip(skb, state->net)) pf = NFPROTO_IPV4; else if (IS_IPV6(skb) || is_vlan_ipv6(skb, state->net) || is_pppoe_ipv6(skb, state->net)) 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(state->net, skb)) return NF_DROP; IPCB(skb)->frag_max_size = nf_bridge->frag_max_size; } if (pf == NFPROTO_IPV6) { if (br_validate_ipv6(state->net, 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, state->net, NULL, skb, brnf_get_logical_dev(skb, state->in, state->net), parent, br_nf_forward_finish); return NF_STOLEN; } static unsigned int br_nf_forward_arp(void *priv, 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); struct brnf_net *brnet; p = br_port_get_rcu(state->out); if (p == NULL) return NF_ACCEPT; br = p->br; brnet = net_generic(state->net, brnf_net_id); if (!brnet->call_arptables && !br_opt_get(br, BROPT_NF_CALL_ARPTABLES)) return NF_ACCEPT; if (!IS_ARP(skb)) { if (!is_vlan_arp(skb, state->net)) return NF_ACCEPT; nf_bridge_pull_encap_header(skb); } if (unlikely(!pskb_may_pull(skb, sizeof(struct arphdr)))) return NF_DROP; if (arp_hdr(skb)->ar_pln != 4) { if (is_vlan_arp(skb, state->net)) nf_bridge_push_encap_header(skb); return NF_ACCEPT; } *d = state->in; NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, state->net, state->sk, skb, state->in, state->out, br_nf_forward_finish); return NF_STOLEN; } static int br_nf_push_frag_xmit(struct net *net, 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_proto) __vlan_hwaccel_put_tag(skb, data->vlan_proto, data->vlan_tci); 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(net, sk, skb); } static int br_nf_ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, int (*output)(struct net *, struct sock *, struct sk_buff *)) { unsigned int mtu = ip_skb_dst_mtu(sk, skb); struct iphdr *iph = ip_hdr(skb); 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(net, IPSTATS_MIB_FRAGFAILS); kfree_skb(skb); return -EMSGSIZE; } return ip_do_fragment(net, sk, skb, output); } static unsigned int nf_bridge_mtu_reduction(const struct sk_buff *skb) { const struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); if (nf_bridge->orig_proto == BRNF_PROTO_PPPOE) return PPPOE_SES_HLEN; return 0; } static int br_nf_dev_queue_xmit(struct net *net, struct sock *sk, struct sk_buff *skb) { struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); unsigned int mtu, mtu_reserved; mtu_reserved = nf_bridge_mtu_reduction(skb); mtu = skb->dev->mtu; if (nf_bridge->pkt_otherhost) { skb->pkt_type = PACKET_OTHERHOST; nf_bridge->pkt_otherhost = false; } if (nf_bridge->frag_max_size && nf_bridge->frag_max_size < mtu) mtu = nf_bridge->frag_max_size; nf_bridge_update_protocol(skb); nf_bridge_push_encap_header(skb); if (skb_is_gso(skb) || skb->len + mtu_reserved <= mtu) { nf_bridge_info_free(skb); return br_dev_queue_push_xmit(net, sk, skb); } /* This is wrong! We should preserve the original fragment * boundaries by preserving frag_list rather than refragmenting. */ if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV4) && skb->protocol == htons(ETH_P_IP)) { struct brnf_frag_data *data; if (br_validate_ipv4(net, skb)) goto drop; IPCB(skb)->frag_max_size = nf_bridge->frag_max_size; data = this_cpu_ptr(&brnf_frag_data_storage); if (skb_vlan_tag_present(skb)) { data->vlan_tci = skb->vlan_tci; data->vlan_proto = skb->vlan_proto; } else { data->vlan_proto = 0; } 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(net, sk, skb, br_nf_push_frag_xmit); } if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV6) && 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(net, skb)) goto drop; IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size; 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(net, sk, skb, br_nf_push_frag_xmit); kfree_skb(skb); return -EMSGSIZE; } nf_bridge_info_free(skb); return br_dev_queue_push_xmit(net, sk, skb); drop: kfree_skb(skb); return 0; } /* PF_BRIDGE/POST_ROUTING ********************************************/ static unsigned int br_nf_post_routing(void *priv, 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, state->net) || is_pppoe_ip(skb, state->net)) pf = NFPROTO_IPV4; else if (IS_IPV6(skb) || is_vlan_ipv6(skb, state->net) || is_pppoe_ipv6(skb, state->net)) pf = NFPROTO_IPV6; else return NF_ACCEPT; 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->net, 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(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) { struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); if (nf_bridge) { if (nf_bridge->sabotage_in_done) return NF_ACCEPT; if (!nf_bridge->in_prerouting && !netif_is_l3_master(skb->dev) && !netif_is_l3_slave(skb->dev)) { nf_bridge->sabotage_in_done = 1; state->okfn(state->net, state->sk, skb); return NF_STOLEN; } } 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->bridged_dnat = 0; 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(dev_net(skb->dev), NULL, skb); } static int br_nf_dev_xmit(struct sk_buff *skb) { const struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); if (nf_bridge && nf_bridge->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, }; /* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because * br_dev_queue_push_xmit is called afterwards */ static const struct nf_hook_ops br_nf_ops[] = { { .hook = br_nf_pre_routing, .pf = NFPROTO_BRIDGE, .hooknum = NF_BR_PRE_ROUTING, .priority = NF_BR_PRI_BRNF, }, #if IS_ENABLED(CONFIG_NF_CONNTRACK) { .hook = br_nf_local_in, .pf = NFPROTO_BRIDGE, .hooknum = NF_BR_LOCAL_IN, .priority = NF_BR_PRI_LAST, }, #endif { .hook = br_nf_forward_ip, .pf = NFPROTO_BRIDGE, .hooknum = NF_BR_FORWARD, .priority = NF_BR_PRI_BRNF - 1, }, { .hook = br_nf_forward_arp, .pf = NFPROTO_BRIDGE, .hooknum = NF_BR_FORWARD, .priority = NF_BR_PRI_BRNF, }, { .hook = br_nf_post_routing, .pf = NFPROTO_BRIDGE, .hooknum = NF_BR_POST_ROUTING, .priority = NF_BR_PRI_LAST, }, { .hook = ip_sabotage_in, .pf = NFPROTO_IPV4, .hooknum = NF_INET_PRE_ROUTING, .priority = NF_IP_PRI_FIRST, }, { .hook = ip_sabotage_in, .pf = NFPROTO_IPV6, .hooknum = NF_INET_PRE_ROUTING, .priority = NF_IP6_PRI_FIRST, }, }; static int brnf_device_event(struct notifier_block *unused, unsigned long event, void *ptr) { struct net_device *dev = netdev_notifier_info_to_dev(ptr); struct brnf_net *brnet; struct net *net; int ret; if (event != NETDEV_REGISTER || !(dev->priv_flags & IFF_EBRIDGE)) return NOTIFY_DONE; ASSERT_RTNL(); net = dev_net(dev); brnet = net_generic(net, brnf_net_id); if (brnet->enabled) return NOTIFY_OK; ret = nf_register_net_hooks(net, br_nf_ops, ARRAY_SIZE(br_nf_ops)); if (ret) return NOTIFY_BAD; brnet->enabled = true; return NOTIFY_OK; } static struct notifier_block brnf_notifier __read_mostly = { .notifier_call = brnf_device_event, }; /* recursively invokes nf_hook_slow (again), skipping already-called * hooks (< NF_BR_PRI_BRNF). * * Called with rcu read lock held. */ int br_nf_hook_thresh(unsigned int hook, struct net *net, struct sock *sk, struct sk_buff *skb, struct net_device *indev, struct net_device *outdev, int (*okfn)(struct net *, struct sock *, struct sk_buff *)) { const struct nf_hook_entries *e; struct nf_hook_state state; struct nf_hook_ops **ops; unsigned int i; int ret; e = rcu_dereference(net->nf.hooks_bridge[hook]); if (!e) return okfn(net, sk, skb); ops = nf_hook_entries_get_hook_ops(e); for (i = 0; i < e->num_hook_entries; i++) { /* These hooks have already been called */ if (ops[i]->priority < NF_BR_PRI_BRNF) continue; /* These hooks have not been called yet, run them. */ if (ops[i]->priority > NF_BR_PRI_BRNF) break; /* take a closer look at NF_BR_PRI_BRNF. */ if (ops[i]->hook == br_nf_pre_routing) { /* This hook diverted the skb to this function, * hooks after this have not been run yet. */ i++; break; } } nf_hook_state_init(&state, hook, NFPROTO_BRIDGE, indev, outdev, sk, net, okfn); ret = nf_hook_slow(skb, &state, e, i); if (ret == 1) ret = okfn(net, sk, skb); return ret; } #ifdef CONFIG_SYSCTL static int brnf_sysctl_call_tables(struct ctl_table *ctl, int write, void *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", .maxlen = sizeof(int), .mode = 0644, .proc_handler = brnf_sysctl_call_tables, }, { .procname = "bridge-nf-call-iptables", .maxlen = sizeof(int), .mode = 0644, .proc_handler = brnf_sysctl_call_tables, }, { .procname = "bridge-nf-call-ip6tables", .maxlen = sizeof(int), .mode = 0644, .proc_handler = brnf_sysctl_call_tables, }, { .procname = "bridge-nf-filter-vlan-tagged", .maxlen = sizeof(int), .mode = 0644, .proc_handler = brnf_sysctl_call_tables, }, { .procname = "bridge-nf-filter-pppoe-tagged", .maxlen = sizeof(int), .mode = 0644, .proc_handler = brnf_sysctl_call_tables, }, { .procname = "bridge-nf-pass-vlan-input-dev", .maxlen = sizeof(int), .mode = 0644, .proc_handler = brnf_sysctl_call_tables, }, { } }; static inline void br_netfilter_sysctl_default(struct brnf_net *brnf) { brnf->call_iptables = 1; brnf->call_ip6tables = 1; brnf->call_arptables = 1; brnf->filter_vlan_tagged = 0; brnf->filter_pppoe_tagged = 0; brnf->pass_vlan_indev = 0; } static int br_netfilter_sysctl_init_net(struct net *net) { struct ctl_table *table = brnf_table; struct brnf_net *brnet; if (!net_eq(net, &init_net)) { table = kmemdup(table, sizeof(brnf_table), GFP_KERNEL); if (!table) return -ENOMEM; } brnet = net_generic(net, brnf_net_id); table[0].data = &brnet->call_arptables; table[1].data = &brnet->call_iptables; table[2].data = &brnet->call_ip6tables; table[3].data = &brnet->filter_vlan_tagged; table[4].data = &brnet->filter_pppoe_tagged; table[5].data = &brnet->pass_vlan_indev; br_netfilter_sysctl_default(brnet); brnet->ctl_hdr = register_net_sysctl(net, "net/bridge", table); if (!brnet->ctl_hdr) { if (!net_eq(net, &init_net)) kfree(table); return -ENOMEM; } return 0; } static void br_netfilter_sysctl_exit_net(struct net *net, struct brnf_net *brnet) { struct ctl_table *table = brnet->ctl_hdr->ctl_table_arg; unregister_net_sysctl_table(brnet->ctl_hdr); if (!net_eq(net, &init_net)) kfree(table); } static int __net_init brnf_init_net(struct net *net) { return br_netfilter_sysctl_init_net(net); } #endif static void __net_exit brnf_exit_net(struct net *net) { struct brnf_net *brnet; brnet = net_generic(net, brnf_net_id); if (brnet->enabled) { nf_unregister_net_hooks(net, br_nf_ops, ARRAY_SIZE(br_nf_ops)); brnet->enabled = false; } #ifdef CONFIG_SYSCTL br_netfilter_sysctl_exit_net(net, brnet); #endif } static struct pernet_operations brnf_net_ops __read_mostly = { #ifdef CONFIG_SYSCTL .init = brnf_init_net, #endif .exit = brnf_exit_net, .id = &brnf_net_id, .size = sizeof(struct brnf_net), }; static int __init br_netfilter_init(void) { int ret; ret = register_pernet_subsys(&brnf_net_ops); if (ret < 0) return ret; ret = register_netdevice_notifier(&brnf_notifier); if (ret < 0) { unregister_pernet_subsys(&brnf_net_ops); return ret; } 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); unregister_netdevice_notifier(&brnf_notifier); unregister_pernet_subsys(&brnf_net_ops); } 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");