// 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 ((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;
|
}
|
|
|
/* 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 && !nf_bridge->in_prerouting &&
|
!netif_is_l3_master(skb->dev) &&
|
!netif_is_l3_slave(skb->dev)) {
|
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 || !(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 <buytenh@gnu.org>");
|
MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
|
MODULE_DESCRIPTION("Linux ethernet netfilter firewall bridge");
|
