--- /dev/null
+/*
+ * Handle firewalling
+ * Linux ethernet bridge
+ *
+ * Authors:
+ * Lennert Buytenhek <buytenh@gnu.org>
+ * Bart De Schuymer <bdschuym@pandora.be>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * Lennert dedicates this file to Kerstin Wurdinger.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/ip.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/if_arp.h>
+#include <linux/if_ether.h>
+#include <linux/if_vlan.h>
+#include <linux/if_pppox.h>
+#include <linux/ppp_defs.h>
+#include <linux/netfilter_bridge.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter_ipv6.h>
+#include <linux/netfilter_arp.h>
+#include <linux/in_route.h>
+#include <linux/inetdevice.h>
+
+#include <net/ip.h>
+#include <net/ipv6.h>
+#include <net/route.h>
+#include <net/netfilter/br_netfilter.h>
+
+#include <asm/uaccess.h>
+#include "br_private.h"
+#ifdef CONFIG_SYSCTL
+#include <linux/sysctl.h>
+#endif
+
+#ifdef CONFIG_SYSCTL
+static struct ctl_table_header *brnf_sysctl_header;
+static int brnf_call_iptables __read_mostly = 1;
+static int brnf_call_ip6tables __read_mostly = 1;
+static int brnf_call_arptables __read_mostly = 1;
+static int brnf_filter_vlan_tagged __read_mostly = 0;
+static int brnf_filter_pppoe_tagged __read_mostly = 0;
+static int brnf_pass_vlan_indev __read_mostly = 0;
+#else
+#define brnf_call_iptables 1
+#define brnf_call_ip6tables 1
+#define brnf_call_arptables 1
+#define brnf_filter_vlan_tagged 0
+#define brnf_filter_pppoe_tagged 0
+#define brnf_pass_vlan_indev 0
+#endif
+
+#define IS_IP(skb) \
+ (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IP))
+
+#define IS_IPV6(skb) \
+ (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IPV6))
+
+#define IS_ARP(skb) \
+ (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_ARP))
+
+static inline __be16 vlan_proto(const struct sk_buff *skb)
+{
+ if (skb_vlan_tag_present(skb))
+ return skb->protocol;
+ else if (skb->protocol == htons(ETH_P_8021Q))
+ return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
+ else
+ return 0;
+}
+
+#define IS_VLAN_IP(skb) \
+ (vlan_proto(skb) == htons(ETH_P_IP) && \
+ brnf_filter_vlan_tagged)
+
+#define IS_VLAN_IPV6(skb) \
+ (vlan_proto(skb) == htons(ETH_P_IPV6) && \
+ brnf_filter_vlan_tagged)
+
+#define IS_VLAN_ARP(skb) \
+ (vlan_proto(skb) == htons(ETH_P_ARP) && \
+ brnf_filter_vlan_tagged)
+
+static inline __be16 pppoe_proto(const struct sk_buff *skb)
+{
+ return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
+ sizeof(struct pppoe_hdr)));
+}
+
+#define IS_PPPOE_IP(skb) \
+ (skb->protocol == htons(ETH_P_PPP_SES) && \
+ pppoe_proto(skb) == htons(PPP_IP) && \
+ brnf_filter_pppoe_tagged)
+
+#define IS_PPPOE_IPV6(skb) \
+ (skb->protocol == htons(ETH_P_PPP_SES) && \
+ pppoe_proto(skb) == htons(PPP_IPV6) && \
+ brnf_filter_pppoe_tagged)
+
+/* largest possible L2 header, see br_nf_dev_queue_xmit() */
+#define NF_BRIDGE_MAX_MAC_HEADER_LENGTH (PPPOE_SES_HLEN + ETH_HLEN)
+
+#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4)
+struct brnf_frag_data {
+ char mac[NF_BRIDGE_MAX_MAC_HEADER_LENGTH];
+ u8 encap_size;
+ u8 size;
+};
+
+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 daddr_was_changed(const struct sk_buff *skb,
+ const struct nf_bridge_info *nf_bridge)
+{
+ return ip_hdr(skb)->daddr != nf_bridge->ipv4_daddr;
+}
+
+/* This requires some explaining. If DNAT has taken place,
+ * we will need to fix up the destination Ethernet address.
+ * This is also true when SNAT takes place (for the reply direction).
+ *
+ * There are two cases to consider:
+ * 1. The packet was DNAT'ed to a device in the same bridge
+ * port group as it was received on. We can still bridge
+ * the packet.
+ * 2. The packet was DNAT'ed to a different device, either
+ * a non-bridged device or another bridge port group.
+ * The packet will need to be routed.
+ *
+ * The correct way of distinguishing between these two cases is to
+ * call ip_route_input() and to look at skb->dst->dev, which is
+ * changed to the destination device if ip_route_input() succeeds.
+ *
+ * Let's first consider the case that ip_route_input() succeeds:
+ *
+ * If the output device equals the logical bridge device the packet
+ * came in on, we can consider this bridging. The corresponding MAC
+ * address will be obtained in br_nf_pre_routing_finish_bridge.
+ * Otherwise, the packet is considered to be routed and we just
+ * change the destination MAC address so that the packet will
+ * later be passed up to the IP stack to be routed. For a redirected
+ * packet, ip_route_input() will give back the localhost as output device,
+ * which differs from the bridge device.
+ *
+ * Let's now consider the case that ip_route_input() fails:
+ *
+ * This can be because the destination address is martian, in which case
+ * the packet will be dropped.
+ * If IP forwarding is disabled, ip_route_input() will fail, while
+ * ip_route_output_key() can return success. The source
+ * address for ip_route_output_key() is set to zero, so ip_route_output_key()
+ * thinks we're handling a locally generated packet and won't care
+ * if IP forwarding is enabled. If the output device equals the logical bridge
+ * device, we proceed as if ip_route_input() succeeded. If it differs from the
+ * logical bridge port or if ip_route_output_key() fails we drop the packet.
+ */
+static int br_nf_pre_routing_finish(struct sock *sk, struct sk_buff *skb)
+{
+ struct net_device *dev = skb->dev;
+ struct iphdr *iph = ip_hdr(skb);
+ struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
+ struct rtable *rt;
+ int err;
+ 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 (daddr_was_changed(skb, nf_bridge)) {
+ if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
+ struct in_device *in_dev = __in_dev_get_rcu(dev);
+
+ /* If err equals -EHOSTUNREACH the error is due to a
+ * martian destination or due to the fact that
+ * forwarding is disabled. For most martian packets,
+ * ip_route_output_key() will fail. It won't fail for 2 types of
+ * martian destinations: loopback destinations and destination
+ * 0.0.0.0. In both cases the packet will be dropped because the
+ * destination is the loopback device and not the bridge. */
+ if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
+ goto free_skb;
+
+ rt = ip_route_output(dev_net(dev), iph->daddr, 0,
+ RT_TOS(iph->tos), 0);
+ if (!IS_ERR(rt)) {
+ /* - Bridged-and-DNAT'ed traffic doesn't
+ * require ip_forwarding. */
+ if (rt->dst.dev == dev) {
+ skb_dst_set(skb, &rt->dst);
+ goto bridged_dnat;
+ }
+ ip_rt_put(rt);
+ }
+free_skb:
+ kfree_skb(skb);
+ return 0;
+ } else {
+ if (skb_dst(skb)->dev == dev) {
+bridged_dnat:
+ skb->dev = nf_bridge->physindev;
+ nf_bridge_update_protocol(skb);
+ nf_bridge_push_encap_header(skb);
+ NF_HOOK_THRESH(NFPROTO_BRIDGE,
+ NF_BR_PRE_ROUTING,
+ sk, skb, skb->dev, NULL,
+ br_nf_pre_routing_finish_bridge,
+ 1);
+ return 0;
+ }
+ ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr);
+ skb->pkt_type = PACKET_HOST;
+ }
+ } else {
+ rt = bridge_parent_rtable(nf_bridge->physindev);
+ if (!rt) {
+ kfree_skb(skb);
+ return 0;
+ }
+ skb_dst_set_noref(skb, &rt->dst);
+ }
+
+ skb->dev = nf_bridge->physindev;
+ nf_bridge_update_protocol(skb);
+ nf_bridge_push_encap_header(skb);
+ NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, sk, skb,
+ skb->dev, NULL,
+ br_handle_frame_finish, 1);
+
+ return 0;
+}
+
+static struct net_device *brnf_get_logical_dev(struct sk_buff *skb, const struct net_device *dev)
+{
+ struct net_device *vlan, *br;
+
+ br = bridge_parent(dev);
+ if (brnf_pass_vlan_indev == 0 || !skb_vlan_tag_present(skb))
+ return br;
+
+ vlan = __vlan_find_dev_deep_rcu(br, skb->vlan_proto,
+ skb_vlan_tag_get(skb) & VLAN_VID_MASK);
+
+ return vlan ? vlan : br;
+}
+
+/* Some common code for IPv4/IPv6 */
+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 nf_bridge_info *nf_bridge;
+ struct net_bridge_port *p;
+ struct net_bridge *br;
+ __u32 len = nf_bridge_encap_header_len(skb);
+
+ if (unlikely(!pskb_may_pull(skb, len)))
+ return NF_DROP;
+
+ p = br_port_get_rcu(state->in);
+ if (p == NULL)
+ return NF_DROP;
+ br = p->br;
+
+ if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb)) {
+ if (!brnf_call_ip6tables && !br->nf_call_ip6tables)
+ return NF_ACCEPT;
+
+ nf_bridge_pull_encap_header_rcsum(skb);
+ return br_nf_pre_routing_ipv6(ops, skb, state);
+ }
+
+ if (!brnf_call_iptables && !br->nf_call_iptables)
+ return NF_ACCEPT;
+
+ if (!IS_IP(skb) && !IS_VLAN_IP(skb) && !IS_PPPOE_IP(skb))
+ return NF_ACCEPT;
+
+ nf_bridge_pull_encap_header_rcsum(skb);
+
+ if (br_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;
+
+ nf_bridge = nf_bridge_info_get(skb);
+ nf_bridge->ipv4_daddr = ip_hdr(skb)->daddr;
+
+ skb->protocol = htons(ETH_P_IP);
+
+ NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, state->sk, skb,
+ skb->dev, NULL,
+ br_nf_pre_routing_finish);
+
+ return NF_STOLEN;
+}
+
+
+/* PF_BRIDGE/LOCAL_IN ************************************************/
+/* The packet is locally destined, which requires a real
+ * dst_entry, so detach the fake one. On the way up, the
+ * packet would pass through PRE_ROUTING again (which already
+ * took place when the packet entered the bridge), but we
+ * register an IPv4 PRE_ROUTING 'sabotage' hook that will
+ * prevent this from happening. */
+static unsigned int br_nf_local_in(const struct nf_hook_ops *ops,
+ struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+ br_drop_fake_rtable(skb);
+ return NF_ACCEPT;
+}
+
+/* PF_BRIDGE/FORWARD *************************************************/
+static int br_nf_forward_finish(struct sock *sk, struct sk_buff *skb)
+{
+ struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
+ struct net_device *in;
+
+ if (!IS_ARP(skb) && !IS_VLAN_ARP(skb)) {
+ 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 <buytenh@gnu.org>");
+MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
+MODULE_DESCRIPTION("Linux ethernet netfilter firewall bridge");
Code Review / kvmfornfv.git / blobdiff