// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Handle firewalling
* Linux ethernet bridge
*
* Authors:
* Lennert Buytenhek <[email protected]>
* Bart De Schuymer <[email protected]>
*
* 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 <net/inet_dscp.h>
#include <linux/uaccess.h>
#include "br_private.h"
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
#endif
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
#include <net/netfilter/nf_conntrack_core.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 {
local_lock_t bh_lock;
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) = {
.bh_lock = INIT_LOCAL_LOCK(bh_lock),
};
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 = skb_ip_totlen(skb);
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)) {
struct net_device *br_indev;
br_indev = nf_bridge_get_physindev(skb, net);
if (!br_indev) {
neigh_release(neigh);
goto free_skb;
}
neigh_hh_bridge(&neigh->hh, skb);
skb->dev = br_indev;
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, *br_indev;
struct iphdr *iph = ip_hdr(skb);
struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
struct rtable *rt;
int err;
br_indev = nf_bridge_get_physindev(skb, net);
if (!br_indev) {
kfree_skb(skb);
return 0;
}
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,
iph->tos & INET_DSCP_MASK, 0,
RT_SCOPE_UNIVERSE);
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 = br_indev;
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(br_indev);
if (!rt) {
kfree_skb(skb);
return 0;
}
skb_dst_drop(skb);
skb_dst_set_noref(skb, &rt->dst);
}
skb->dev = br_indev;
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->physinif = skb->dev->ifindex;
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_REASON(skb, SKB_DROP_REASON_PKT_TOO_SMALL, 0);
p = br_port_get_rcu(state->in);
if (p == NULL)
return NF_DROP_REASON(skb, SKB_DROP_REASON_DEV_READY, 0);
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_REASON(skb, SKB_DROP_REASON_IPV6DISABLED, 0);
}
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_REASON(skb, SKB_DROP_REASON_IP_INHDR, 0);
if (!nf_bridge_alloc(skb))
return NF_DROP_REASON(skb, SKB_DROP_REASON_NOMEM, 0);
if (!setup_pre_routing(skb, state->net))
return NF_DROP_REASON(skb, SKB_DROP_REASON_DEV_READY, 0);
nf_bridge = nf_bridge_info_get(skb);
nf_bridge->ipv4_daddr = ip_hdr(skb)->daddr;
skb->protocol = htons(ETH_P_IP);
skb->transport_header = skb->network_header + ip_hdr(skb)->ihl * 4;
NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, state->net, state->sk, skb,
skb->dev, NULL,
br_nf_pre_routing_finish);
return NF_STOLEN;
}
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
/* conntracks' nf_confirm logic cannot handle cloned skbs referencing
* the same nf_conn entry, which will happen for multicast (broadcast)
* Frames on bridges.
*
* Example:
* macvlan0
* br0
* ethX ethY
*
* ethX (or Y) receives multicast or broadcast packet containing
* an IP packet, not yet in conntrack table.
*
* 1. skb passes through bridge and fake-ip (br_netfilter)Prerouting.
* -> skb->_nfct now references a unconfirmed entry
* 2. skb is broad/mcast packet. bridge now passes clones out on each bridge
* interface.
* 3. skb gets passed up the stack.
* 4. In macvlan case, macvlan driver retains clone(s) of the mcast skb
* and schedules a work queue to send them out on the lower devices.
*
* The clone skb->_nfct is not a copy, it is the same entry as the
* original skb. The macvlan rx handler then returns RX_HANDLER_PASS.
* 5. Normal conntrack hooks (in NF_INET_LOCAL_IN) confirm the orig skb.
*
* The Macvlan broadcast worker and normal confirm path will race.
*
* This race will not happen if step 2 already confirmed a clone. In that
* case later steps perform skb_clone() with skb->_nfct already confirmed (in
* hash table). This works fine.
*
* But such confirmation won't happen when eb/ip/nftables rules dropped the
* packets before they reached the nf_confirm step in postrouting.
*
* Work around this problem by explicit confirmation of the entry at
* LOCAL_IN time, before upper layer has a chance to clone the unconfirmed
* entry.
*
*/
static unsigned int br_nf_local_in(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
bool promisc = BR_INPUT_SKB_CB(skb)->promisc;
struct nf_conntrack *nfct = skb_nfct(skb);
const struct nf_ct_hook *ct_hook;
struct nf_conn *ct;
int ret;
if (promisc) {
nf_reset_ct(skb);
return NF_ACCEPT;
}
if (!nfct || skb->pkt_type == PACKET_HOST)
return NF_ACCEPT;
ct = container_of(nfct, struct nf_conn, ct_general);
if (likely(nf_ct_is_confirmed(ct)))
return NF_ACCEPT;
if (WARN_ON_ONCE(refcount_read(&nfct->use) != 1)) {
nf_reset_ct(skb);
return NF_ACCEPT;
}
WARN_ON_ONCE(skb_shared(skb));
/* We can't call nf_confirm here, it would create a dependency
* on nf_conntrack module.
*/
ct_hook = rcu_dereference(nf_ct_hook);
if (!ct_hook) {
skb->_nfct = 0ul;
nf_conntrack_put(nfct);
return NF_ACCEPT;
}
nf_bridge_pull_encap_header(skb);
ret = ct_hook->confirm(skb);
switch (ret & NF_VERDICT_MASK) {
case NF_STOLEN:
return NF_STOLEN;
default:
nf_bridge_push_encap_header(skb);
break;
}
ct = container_of(nfct, struct nf_conn, ct_general);
WARN_ON_ONCE(!nf_ct_is_confirmed(ct));
return ret;
}
#endif
/* PF_BRIDGE/FORWARD *************************************************/
static int br_nf_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
{
struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
struct net_device *in;
if (!IS_ARP(skb) && !is_vlan_arp(skb, net)) {
if (skb->protocol == htons(ETH_P_IP))
nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
if (skb->protocol == htons(ETH_P_IPV6))
nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size;
in = nf_bridge_get_physindev(skb, net);
if (!in) {
kfree_skb(skb);
return 0;
}
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;
}
static unsigned int br_nf_forward_ip(struct sk_buff *skb,
const struct nf_hook_state *state,
u8 pf)
{
struct nf_bridge_info *nf_bridge;
struct net_device *parent;
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_REASON(skb, SKB_DROP_REASON_NOMEM, 0);
nf_bridge = nf_bridge_info_get(skb);
if (!nf_bridge)
return NF_DROP_REASON(skb, SKB_DROP_REASON_NOMEM, 0);
parent = bridge_parent(state->out);
if (!parent)
return NF_DROP_REASON(skb, SKB_DROP_REASON_DEV_READY, 0);
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_REASON(skb, SKB_DROP_REASON_IP_INHDR, 0);
IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
skb->protocol = htons(ETH_P_IP);
} else if (pf == NFPROTO_IPV6) {
if (br_validate_ipv6(state->net, skb))
return NF_DROP_REASON(skb, SKB_DROP_REASON_IP_INHDR, 0);
IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
skb->protocol = htons(ETH_P_IPV6);
} else {
WARN_ON_ONCE(1);
return NF_DROP;
}
nf_bridge->physoutdev = skb->dev;
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(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_vlan_arp(skb, state->net))
nf_bridge_pull_encap_header(skb);
if (unlikely(!pskb_may_pull(skb, sizeof(struct arphdr))))
return NF_DROP_REASON(skb, SKB_DROP_REASON_PKT_TOO_SMALL, 0);
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;
}
/* 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(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
if (IS_IP(skb) || is_vlan_ip(skb, state->net) ||
is_pppoe_ip(skb, state->net))
return br_nf_forward_ip(skb, state, NFPROTO_IPV4);
if (IS_IPV6(skb) || is_vlan_ipv6(skb, state->net) ||
is_pppoe_ipv6(skb, state->net))
return br_nf_forward_ip(skb, state, NFPROTO_IPV6);
if (IS_ARP(skb) || is_vlan_arp(skb, state->net))
return br_nf_forward_arp(skb, state);
return NF_ACCEPT;
}
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;
int ret;
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;
local_lock_nested_bh(&brnf_frag_data_storage.bh_lock);
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);
ret = br_nf_ip_fragment(net, sk, skb, br_nf_push_frag_xmit);
local_unlock_nested_bh(&brnf_frag_data_storage.bh_lock);
return ret;
}
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;
local_lock_nested_bh(&brnf_frag_data_storage.bh_lock);
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) {
ret = v6ops->fragment(net, sk, skb, br_nf_push_frag_xmit);
local_unlock_nested_bh(&brnf_frag_data_storage.bh_lock);
return ret;
}
local_unlock_nested_bh(&brnf_frag_data_storage.bh_lock);
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_REASON(skb, SKB_DROP_REASON_DEV_READY, 0);
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);
struct net_device *br_indev;
br_indev = nf_bridge_get_physindev(skb, dev_net(skb->dev));
if (!br_indev) {
kfree_skb(skb);
return;
}
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 = br_indev;
nf_bridge->physoutdev = NULL;
br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
}
static int br_nf_dev_xmit(struct sk_buff *skb)
{
const struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
if (nf_bridge && nf_bridge->bridged_dnat) {
br_nf_pre_routing_finish_bridge_slow(skb);
return 1;
}
return 0;
}
static const struct nf_br_ops br_ops = {
.br_dev_xmit_hook = br_nf_dev_xmit,
};
/* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
* br_dev_queue_push_xmit is called afterwards */
static const struct nf_hook_ops br_nf_ops[] = {
{
.hook = br_nf_pre_routing,
.pf = NFPROTO_BRIDGE,
.hooknum = NF_BR_PRE_ROUTING,
.priority = NF_BR_PRI_BRNF,
},
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
{
.hook = br_nf_local_in,
.pf = NFPROTO_BRIDGE,
.hooknum = NF_BR_LOCAL_IN,
.priority = NF_BR_PRI_LAST,
},
#endif
{
.hook = br_nf_forward,
.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(const 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_sz(net, "net/bridge", table,
ARRAY_SIZE(brnf_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)
{
const 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 <[email protected]>");
MODULE_AUTHOR("Bart De Schuymer <[email protected]>");
MODULE_DESCRIPTION("Linux ethernet netfilter firewall bridge");
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