/* Replicate the checks that IPv6 does on packet reception and pass the packet * to ip6tables. */ unsigned int br_nf_pre_routing_ipv6(const struct nf_hook_ops *ops, struct sk_buff *skb, const struct nf_hook_state *state) { struct nf_bridge_info *nf_bridge; if (br_validate_ipv6(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->ipv6_daddr = ipv6_hdr(skb)->daddr; 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; }
/* 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)) { 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; }
/* 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; }
/* 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; }
/* 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; }
/* 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); 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(priv, 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(state->net, 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->net, state->sk, skb, skb->dev, NULL, br_nf_pre_routing_finish); return NF_STOLEN; }
/* PF_BRIDGE/PRE_ROUTING: Undo the changes made for ip6tables * PREROUTING and continue the bridge PRE_ROUTING hook. See comment * for br_nf_pre_routing_finish(), same logic is used here but * equivalent IPv6 function ip6_route_input() called indirectly. */ 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; struct net_device *dev = skb->dev; const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops(); nf_bridge->frag_max_size = IP6CB(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_ipv6_daddr_was_changed(skb, nf_bridge)) { skb_dst_drop(skb); v6ops->route_input(skb); if (skb_dst(skb)->error) { kfree_skb(skb); return 0; } if (skb_dst(skb)->dev == dev) { 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; }
/* 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); }
/* 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); }
/* 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) || 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->net, state->sk, skb, NULL, realoutdev, br_nf_dev_queue_xmit); return NF_STOLEN; }
/* 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->in_prerouting = 1; 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; }
/* 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->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 int br_nf_dev_queue_xmit(struct net *net, 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(net, sk, skb); } nf_bridge = nf_bridge_info_get(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; 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(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; 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(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; }
/* 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_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_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; }