/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/types.h>
#include <linux/ip.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv6.h>
#include <linux/netfilter_bridge.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/icmp.h>
#include <linux/sysctl.h>
#include <net/route.h>
#include <net/ip.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_bridge.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables.h>
#include "../br_private.h"
/* Best effort variant of ip_do_fragment which preserves geometry, unless skbuff
* has been linearized or cloned.
*/
static int nf_br_ip_fragment(struct net *net, struct sock *sk,
struct sk_buff *skb,
struct nf_bridge_frag_data *data,
int (*output)(struct net *, struct sock *sk,
const struct nf_bridge_frag_data *data,
struct sk_buff *))
{
int frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size;
u8 tstamp_type = skb->tstamp_type;
unsigned int hlen, ll_rs, mtu;
ktime_t tstamp = skb->tstamp;
struct ip_frag_state state;
struct iphdr *iph;
int err = 0;
/* for offloaded checksums cleanup checksum before fragmentation */
if (skb->ip_summed == CHECKSUM_PARTIAL &&
(err = skb_checksum_help(skb)))
goto blackhole;
iph = ip_hdr(skb);
/*
* Setup starting values
*/
hlen = iph->ihl * 4;
frag_max_size -= hlen;
ll_rs = LL_RESERVED_SPACE(skb->dev);
mtu = skb->dev->mtu;
if (skb_has_frag_list(skb)) {
unsigned int first_len = skb_pagelen(skb);
struct ip_fraglist_iter iter;
struct sk_buff *frag;
if (first_len - hlen > mtu ||
skb_headroom(skb) < ll_rs)
goto blackhole;
if (skb_cloned(skb))
goto slow_path;
skb_walk_frags(skb, frag) {
if (frag->len > mtu ||
skb_headroom(frag) < hlen + ll_rs)
goto blackhole;
if (skb_shared(frag))
goto slow_path;
}
ip_fraglist_init(skb, iph, hlen, &iter);
for (;;) {
if (iter.frag)
ip_fraglist_prepare(skb, &iter);
skb_set_delivery_time(skb, tstamp, tstamp_type);
err = output(net, sk, data, skb);
if (err || !iter.frag)
break;
skb = ip_fraglist_next(&iter);
}
if (!err)
return 0;
kfree_skb_list(iter.frag);
return err;
}
slow_path:
/* This is a linearized skbuff, the original geometry is lost for us.
* This may also be a clone skbuff, we could preserve the geometry for
* the copies but probably not worth the effort.
*/
ip_frag_init(skb, hlen, ll_rs, frag_max_size, false, &state);
while (state.left > 0) {
struct sk_buff *skb2;
skb2 = ip_frag_next(skb, &state);
if (IS_ERR(skb2)) {
err = PTR_ERR(skb2);
goto blackhole;
}
skb_set_delivery_time(skb2, tstamp, tstamp_type);
err = output(net, sk, data, skb2);
if (err)
goto blackhole;
}
consume_skb(skb);
return err;
blackhole:
kfree_skb(skb);
return 0;
}
/* ip_defrag() expects IPCB() in place. */
static void br_skb_cb_save(struct sk_buff *skb, struct br_input_skb_cb *cb,
size_t inet_skb_parm_size)
{
memcpy(cb, skb->cb, sizeof(*cb));
memset(skb->cb, 0, inet_skb_parm_size);
}
static void br_skb_cb_restore(struct sk_buff *skb,
const struct br_input_skb_cb *cb,
u16 fragsz)
{
memcpy(skb->cb, cb, sizeof(*cb));
BR_INPUT_SKB_CB(skb)->frag_max_size = fragsz;
}
static unsigned int nf_ct_br_defrag4(struct sk_buff *skb,
const struct nf_hook_state *state)
{
u16 zone_id = NF_CT_DEFAULT_ZONE_ID;
enum ip_conntrack_info ctinfo;
struct br_input_skb_cb cb;
const struct nf_conn *ct;
int err;
if (!ip_is_fragment(ip_hdr(skb)))
return NF_ACCEPT;
ct = nf_ct_get(skb, &ctinfo);
if (ct)
zone_id = nf_ct_zone_id(nf_ct_zone(ct), CTINFO2DIR(ctinfo));
br_skb_cb_save(skb, &cb, sizeof(struct inet_skb_parm));
local_bh_disable();
err = ip_defrag(state->net, skb,
IP_DEFRAG_CONNTRACK_BRIDGE_IN + zone_id);
local_bh_enable();
if (!err) {
br_skb_cb_restore(skb, &cb, IPCB(skb)->frag_max_size);
skb->ignore_df = 1;
return NF_ACCEPT;
}
return NF_STOLEN;
}
static unsigned int nf_ct_br_defrag6(struct sk_buff *skb,
const struct nf_hook_state *state)
{
#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
u16 zone_id = NF_CT_DEFAULT_ZONE_ID;
enum ip_conntrack_info ctinfo;
struct br_input_skb_cb cb;
const struct nf_conn *ct;
int err;
ct = nf_ct_get(skb, &ctinfo);
if (ct)
zone_id = nf_ct_zone_id(nf_ct_zone(ct), CTINFO2DIR(ctinfo));
br_skb_cb_save(skb, &cb, sizeof(struct inet6_skb_parm));
err = nf_ct_frag6_gather(state->net, skb,
IP_DEFRAG_CONNTRACK_BRIDGE_IN + zone_id);
/* queued */
if (err == -EINPROGRESS)
return NF_STOLEN;
br_skb_cb_restore(skb, &cb, IP6CB(skb)->frag_max_size);
return err == 0 ? NF_ACCEPT : NF_DROP;
#else
return NF_ACCEPT;
#endif
}
static int nf_ct_br_ip_check(const struct sk_buff *skb)
{
const struct iphdr *iph;
int nhoff, len;
nhoff = skb_network_offset(skb);
iph = ip_hdr(skb);
if (iph->ihl < 5 ||
iph->version != 4)
return -1;
len = skb_ip_totlen(skb);
if (skb->len < nhoff + len ||
len < (iph->ihl * 4))
return -1;
return 0;
}
static int nf_ct_br_ipv6_check(const struct sk_buff *skb)
{
const struct ipv6hdr *hdr;
int nhoff, len;
nhoff = skb_network_offset(skb);
hdr = ipv6_hdr(skb);
if (hdr->version != 6)
return -1;
len = ntohs(hdr->payload_len) + sizeof(struct ipv6hdr) + nhoff;
if (skb->len < len)
return -1;
return 0;
}
static unsigned int nf_ct_bridge_pre(void *priv, struct sk_buff *skb,
const struct nf_hook_state *state)
{
struct nf_hook_state bridge_state = *state;
enum ip_conntrack_info ctinfo;
struct nf_conn *ct;
u32 len;
int ret;
ct = nf_ct_get(skb, &ctinfo);
if ((ct && !nf_ct_is_template(ct)) ||
ctinfo == IP_CT_UNTRACKED)
return NF_ACCEPT;
switch (skb->protocol) {
case htons(ETH_P_IP):
if (!pskb_may_pull(skb, sizeof(struct iphdr)))
return NF_ACCEPT;
len = skb_ip_totlen(skb);
if (pskb_trim_rcsum(skb, len))
return NF_ACCEPT;
if (nf_ct_br_ip_check(skb))
return NF_ACCEPT;
bridge_state.pf = NFPROTO_IPV4;
ret = nf_ct_br_defrag4(skb, &bridge_state);
break;
case htons(ETH_P_IPV6):
if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
return NF_ACCEPT;
len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
if (pskb_trim_rcsum(skb, len))
return NF_ACCEPT;
if (nf_ct_br_ipv6_check(skb))
return NF_ACCEPT;
bridge_state.pf = NFPROTO_IPV6;
ret = nf_ct_br_defrag6(skb, &bridge_state);
break;
default:
nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
return NF_ACCEPT;
}
if (ret != NF_ACCEPT)
return ret;
return nf_conntrack_in(skb, &bridge_state);
}
static unsigned int nf_ct_bridge_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);
struct nf_conn *ct;
if (promisc) {
nf_reset_ct(skb);
return NF_ACCEPT;
}
if (!nfct || skb->pkt_type == PACKET_HOST)
return NF_ACCEPT;
/* nf_conntrack_confirm() cannot handle concurrent clones,
* this happens for broad/multicast frames with e.g. macvlan on top
* of the bridge device.
*/
ct = container_of(nfct, struct nf_conn, ct_general);
if (nf_ct_is_confirmed(ct) || nf_ct_is_template(ct))
return NF_ACCEPT;
/* let inet prerouting call conntrack again */
skb->_nfct = 0;
nf_ct_put(ct);
return NF_ACCEPT;
}
static void nf_ct_bridge_frag_save(struct sk_buff *skb,
struct nf_bridge_frag_data *data)
{
if (skb_vlan_tag_present(skb)) {
data->vlan_present = true;
data->vlan_tci = skb->vlan_tci;
data->vlan_proto = skb->vlan_proto;
} else {
data->vlan_present = false;
}
skb_copy_from_linear_data_offset(skb, -ETH_HLEN, data->mac, ETH_HLEN);
}
static unsigned int
nf_ct_bridge_refrag(struct sk_buff *skb, const struct nf_hook_state *state,
int (*output)(struct net *, struct sock *sk,
const struct nf_bridge_frag_data *data,
struct sk_buff *))
{
struct nf_bridge_frag_data data;
if (!BR_INPUT_SKB_CB(skb)->frag_max_size)
return NF_ACCEPT;
nf_ct_bridge_frag_save(skb, &data);
switch (skb->protocol) {
case htons(ETH_P_IP):
nf_br_ip_fragment(state->net, state->sk, skb, &data, output);
break;
case htons(ETH_P_IPV6):
nf_br_ip6_fragment(state->net, state->sk, skb, &data, output);
break;
default:
WARN_ON_ONCE(1);
return NF_DROP;
}
return NF_STOLEN;
}
/* Actually only slow path refragmentation needs this. */
static int nf_ct_bridge_frag_restore(struct sk_buff *skb,
const struct nf_bridge_frag_data *data)
{
int err;
err = skb_cow_head(skb, ETH_HLEN);
if (err) {
kfree_skb(skb);
return -ENOMEM;
}
if (data->vlan_present)
__vlan_hwaccel_put_tag(skb, data->vlan_proto, data->vlan_tci);
else if (skb_vlan_tag_present(skb))
__vlan_hwaccel_clear_tag(skb);
skb_copy_to_linear_data_offset(skb, -ETH_HLEN, data->mac, ETH_HLEN);
skb_reset_mac_header(skb);
return 0;
}
static int nf_ct_bridge_refrag_post(struct net *net, struct sock *sk,
const struct nf_bridge_frag_data *data,
struct sk_buff *skb)
{
int err;
err = nf_ct_bridge_frag_restore(skb, data);
if (err < 0)
return err;
return br_dev_queue_push_xmit(net, sk, skb);
}
static unsigned int nf_ct_bridge_post(void *priv, struct sk_buff *skb,
const struct nf_hook_state *state)
{
int ret;
ret = nf_confirm(priv, skb, state);
if (ret != NF_ACCEPT)
return ret;
return nf_ct_bridge_refrag(skb, state, nf_ct_bridge_refrag_post);
}
static struct nf_hook_ops nf_ct_bridge_hook_ops[] __read_mostly = {
{
.hook = nf_ct_bridge_pre,
.pf = NFPROTO_BRIDGE,
.hooknum = NF_BR_PRE_ROUTING,
.priority = NF_IP_PRI_CONNTRACK,
},
{
.hook = nf_ct_bridge_in,
.pf = NFPROTO_BRIDGE,
.hooknum = NF_BR_LOCAL_IN,
.priority = NF_IP_PRI_CONNTRACK_CONFIRM,
},
{
.hook = nf_ct_bridge_post,
.pf = NFPROTO_BRIDGE,
.hooknum = NF_BR_POST_ROUTING,
.priority = NF_IP_PRI_CONNTRACK_CONFIRM,
},
};
static struct nf_ct_bridge_info bridge_info = {
.ops = nf_ct_bridge_hook_ops,
.ops_size = ARRAY_SIZE(nf_ct_bridge_hook_ops),
.me = THIS_MODULE,
};
static int __init nf_conntrack_l3proto_bridge_init(void)
{
nf_ct_bridge_register(&bridge_info);
return 0;
}
static void __exit nf_conntrack_l3proto_bridge_fini(void)
{
nf_ct_bridge_unregister(&bridge_info);
}
module_init(nf_conntrack_l3proto_bridge_init);
module_exit(nf_conntrack_l3proto_bridge_fini);
MODULE_ALIAS("nf_conntrack-" __stringify(AF_BRIDGE));
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Bridge IPv4 and IPv6 connection tracking");
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