| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* |
| * Handle firewalling |
| * Linux ethernet bridge |
| * |
| * Authors: |
| * Lennert Buytenhek <buytenh@gnu.org> |
| * Bart De Schuymer <bdschuym@pandora.be> |
| * |
| * 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 <uapi/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/rculist.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 <net/netns/generic.h> |
| |
| #include <linux/uaccess.h> |
| #include "br_private.h" |
| #ifdef CONFIG_SYSCTL |
| #include <linux/sysctl.h> |
| #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 ((READ_ONCE(neigh->nud_state) & NUD_CONNECTED) && |
| READ_ONCE(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 = READ_ONCE(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; |
| } |
| |
| |
| /* 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, |
| }, |
| { |
| .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 || !netif_is_bridge_master(dev)) |
| 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 <buytenh@gnu.org>"); |
| MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>"); |
| MODULE_DESCRIPTION("Linux ethernet netfilter firewall bridge"); |