// SPDX-License-Identifier: GPL-2.0
#include <linux/types.h>
#include <linux/netfilter.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/vmalloc.h>
#include <linux/stddef.h>
#include <linux/err.h>
#include <linux/percpu.h>
#include <linux/notifier.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_l4proto.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_bridge.h>
#include <net/netfilter/nf_log.h>
#include <linux/ip.h>
#include <linux/icmp.h>
#include <linux/sysctl.h>
#include <net/route.h>
#include <net/ip.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv6.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_zones.h>
#include <net/netfilter/nf_conntrack_seqadj.h>
#include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
#include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
#include <net/netfilter/nf_nat_helper.h>
#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
#include <linux/ipv6.h>
#include <linux/in6.h>
#include <net/ipv6.h>
#include <net/inet_frag.h>
static DEFINE_MUTEX(nf_ct_proto_mutex);
#ifdef CONFIG_SYSCTL
__printf(4, 5)
void nf_l4proto_log_invalid(const struct sk_buff *skb,
const struct nf_hook_state *state,
u8 protonum,
const char *fmt, ...)
{
struct net *net = state->net;
struct va_format vaf;
va_list args;
if (net->ct.sysctl_log_invalid != protonum &&
net->ct.sysctl_log_invalid != IPPROTO_RAW)
return;
va_start(args, fmt);
vaf.fmt = fmt;
vaf.va = &args;
nf_log_packet(net, state->pf, 0, skb, state->in, state->out,
NULL, "nf_ct_proto_%d: %pV ", protonum, &vaf);
va_end(args);
}
EXPORT_SYMBOL_GPL(nf_l4proto_log_invalid);
__printf(4, 5)
void nf_ct_l4proto_log_invalid(const struct sk_buff *skb,
const struct nf_conn *ct,
const struct nf_hook_state *state,
const char *fmt, ...)
{
struct va_format vaf;
struct net *net;
va_list args;
net = nf_ct_net(ct);
if (likely(net->ct.sysctl_log_invalid == 0))
return;
va_start(args, fmt);
vaf.fmt = fmt;
vaf.va = &args;
nf_l4proto_log_invalid(skb, state,
nf_ct_protonum(ct), "%pV", &vaf);
va_end(args);
}
EXPORT_SYMBOL_GPL(nf_ct_l4proto_log_invalid);
#endif
const struct nf_conntrack_l4proto *nf_ct_l4proto_find(u8 l4proto)
{
switch (l4proto) {
case IPPROTO_UDP: return &nf_conntrack_l4proto_udp;
case IPPROTO_TCP: return &nf_conntrack_l4proto_tcp;
case IPPROTO_ICMP: return &nf_conntrack_l4proto_icmp;
#ifdef CONFIG_NF_CT_PROTO_DCCP
case IPPROTO_DCCP: return &nf_conntrack_l4proto_dccp;
#endif
#ifdef CONFIG_NF_CT_PROTO_SCTP
case IPPROTO_SCTP: return &nf_conntrack_l4proto_sctp;
#endif
#ifdef CONFIG_NF_CT_PROTO_UDPLITE
case IPPROTO_UDPLITE: return &nf_conntrack_l4proto_udplite;
#endif
#ifdef CONFIG_NF_CT_PROTO_GRE
case IPPROTO_GRE: return &nf_conntrack_l4proto_gre;
#endif
#if IS_ENABLED(CONFIG_IPV6)
case IPPROTO_ICMPV6: return &nf_conntrack_l4proto_icmpv6;
#endif /* CONFIG_IPV6 */
}
return &nf_conntrack_l4proto_generic;
};
EXPORT_SYMBOL_GPL(nf_ct_l4proto_find);
static bool in_vrf_postrouting(const struct nf_hook_state *state)
{
#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
if (state->hook == NF_INET_POST_ROUTING &&
netif_is_l3_master(state->out))
return true;
#endif
return false;
}
unsigned int nf_confirm(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
const struct nf_conn_help *help;
enum ip_conntrack_info ctinfo;
unsigned int protoff;
struct nf_conn *ct;
bool seqadj_needed;
__be16 frag_off;
int start;
u8 pnum;
ct = nf_ct_get(skb, &ctinfo);
if (!ct || in_vrf_postrouting(state))
return NF_ACCEPT;
help = nfct_help(ct);
seqadj_needed = test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) && !nf_is_loopback_packet(skb);
if (!help && !seqadj_needed)
return nf_conntrack_confirm(skb);
/* helper->help() do not expect ICMP packets */
if (ctinfo == IP_CT_RELATED_REPLY)
return nf_conntrack_confirm(skb);
switch (nf_ct_l3num(ct)) {
case NFPROTO_IPV4:
protoff = skb_network_offset(skb) + ip_hdrlen(skb);
break;
case NFPROTO_IPV6:
pnum = ipv6_hdr(skb)->nexthdr;
start = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &pnum, &frag_off);
if (start < 0 || (frag_off & htons(~0x7)) != 0)
return nf_conntrack_confirm(skb);
protoff = start;
break;
default:
return nf_conntrack_confirm(skb);
}
if (help) {
const struct nf_conntrack_helper *helper;
int ret;
/* rcu_read_lock()ed by nf_hook */
helper = rcu_dereference(help->helper);
if (helper) {
ret = helper->help(skb,
protoff,
ct, ctinfo);
if (ret != NF_ACCEPT)
return ret;
}
}
if (seqadj_needed &&
!nf_ct_seq_adjust(skb, ct, ctinfo, protoff)) {
NF_CT_STAT_INC_ATOMIC(nf_ct_net(ct), drop);
return NF_DROP;
}
/* We've seen it coming out the other side: confirm it */
return nf_conntrack_confirm(skb);
}
EXPORT_SYMBOL_GPL(nf_confirm);
static unsigned int ipv4_conntrack_in(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
return nf_conntrack_in(skb, state);
}
static unsigned int ipv4_conntrack_local(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
if (ip_is_fragment(ip_hdr(skb))) { /* IP_NODEFRAG setsockopt set */
enum ip_conntrack_info ctinfo;
struct nf_conn *tmpl;
tmpl = nf_ct_get(skb, &ctinfo);
if (tmpl && nf_ct_is_template(tmpl)) {
/* when skipping ct, clear templates to avoid fooling
* later targets/matches
*/
skb->_nfct = 0;
nf_ct_put(tmpl);
}
return NF_ACCEPT;
}
return nf_conntrack_in(skb, state);
}
/* Connection tracking may drop packets, but never alters them, so
* make it the first hook.
*/
static const struct nf_hook_ops ipv4_conntrack_ops[] = {
{
.hook = ipv4_conntrack_in,
.pf = NFPROTO_IPV4,
.hooknum = NF_INET_PRE_ROUTING,
.priority = NF_IP_PRI_CONNTRACK,
},
{
.hook = ipv4_conntrack_local,
.pf = NFPROTO_IPV4,
.hooknum = NF_INET_LOCAL_OUT,
.priority = NF_IP_PRI_CONNTRACK,
},
{
.hook = nf_confirm,
.pf = NFPROTO_IPV4,
.hooknum = NF_INET_POST_ROUTING,
.priority = NF_IP_PRI_CONNTRACK_CONFIRM,
},
{
.hook = nf_confirm,
.pf = NFPROTO_IPV4,
.hooknum = NF_INET_LOCAL_IN,
.priority = NF_IP_PRI_CONNTRACK_CONFIRM,
},
};
/* Fast function for those who don't want to parse /proc (and I don't
* blame them).
* Reversing the socket's dst/src point of view gives us the reply
* mapping.
*/
static int
getorigdst(struct sock *sk, int optval, void __user *user, int *len)
{
const struct inet_sock *inet = inet_sk(sk);
const struct nf_conntrack_tuple_hash *h;
struct nf_conntrack_tuple tuple;
memset(&tuple, 0, sizeof(tuple));
lock_sock(sk);
tuple.src.u3.ip = inet->inet_rcv_saddr;
tuple.src.u.tcp.port = inet->inet_sport;
tuple.dst.u3.ip = inet->inet_daddr;
tuple.dst.u.tcp.port = inet->inet_dport;
tuple.src.l3num = PF_INET;
tuple.dst.protonum = sk->sk_protocol;
release_sock(sk);
/* We only do TCP and SCTP at the moment: is there a better way? */
if (tuple.dst.protonum != IPPROTO_TCP &&
tuple.dst.protonum != IPPROTO_SCTP)
return -ENOPROTOOPT;
if ((unsigned int)*len < sizeof(struct sockaddr_in))
return -EINVAL;
h = nf_conntrack_find_get(sock_net(sk), &nf_ct_zone_dflt, &tuple);
if (h) {
struct sockaddr_in sin;
struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
sin.sin_family = AF_INET;
sin.sin_port = ct->tuplehash[IP_CT_DIR_ORIGINAL]
.tuple.dst.u.tcp.port;
sin.sin_addr.s_addr = ct->tuplehash[IP_CT_DIR_ORIGINAL]
.tuple.dst.u3.ip;
memset(sin.sin_zero, 0, sizeof(sin.sin_zero));
nf_ct_put(ct);
if (copy_to_user(user, &sin, sizeof(sin)) != 0)
return -EFAULT;
else
return 0;
}
return -ENOENT;
}
static struct nf_sockopt_ops so_getorigdst = {
.pf = PF_INET,
.get_optmin = SO_ORIGINAL_DST,
.get_optmax = SO_ORIGINAL_DST + 1,
.get = getorigdst,
.owner = THIS_MODULE,
};
#if IS_ENABLED(CONFIG_IPV6)
static int
ipv6_getorigdst(struct sock *sk, int optval, void __user *user, int *len)
{
struct nf_conntrack_tuple tuple = { .src.l3num = NFPROTO_IPV6 };
const struct ipv6_pinfo *inet6 = inet6_sk(sk);
const struct inet_sock *inet = inet_sk(sk);
const struct nf_conntrack_tuple_hash *h;
struct sockaddr_in6 sin6;
struct nf_conn *ct;
__be32 flow_label;
int bound_dev_if;
lock_sock(sk);
tuple.src.u3.in6 = sk->sk_v6_rcv_saddr;
tuple.src.u.tcp.port = inet->inet_sport;
tuple.dst.u3.in6 = sk->sk_v6_daddr;
tuple.dst.u.tcp.port = inet->inet_dport;
tuple.dst.protonum = sk->sk_protocol;
bound_dev_if = sk->sk_bound_dev_if;
flow_label = inet6->flow_label;
release_sock(sk);
if (tuple.dst.protonum != IPPROTO_TCP &&
tuple.dst.protonum != IPPROTO_SCTP)
return -ENOPROTOOPT;
if (*len < 0 || (unsigned int)*len < sizeof(sin6))
return -EINVAL;
h = nf_conntrack_find_get(sock_net(sk), &nf_ct_zone_dflt, &tuple);
if (!h)
return -ENOENT;
ct = nf_ct_tuplehash_to_ctrack(h);
sin6.sin6_family = AF_INET6;
sin6.sin6_port = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u.tcp.port;
sin6.sin6_flowinfo = flow_label & IPV6_FLOWINFO_MASK;
memcpy(&sin6.sin6_addr,
&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.in6,
sizeof(sin6.sin6_addr));
nf_ct_put(ct);
sin6.sin6_scope_id = ipv6_iface_scope_id(&sin6.sin6_addr, bound_dev_if);
return copy_to_user(user, &sin6, sizeof(sin6)) ? -EFAULT : 0;
}
static struct nf_sockopt_ops so_getorigdst6 = {
.pf = NFPROTO_IPV6,
.get_optmin = IP6T_SO_ORIGINAL_DST,
.get_optmax = IP6T_SO_ORIGINAL_DST + 1,
.get = ipv6_getorigdst,
.owner = THIS_MODULE,
};
static unsigned int ipv6_conntrack_in(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
return nf_conntrack_in(skb, state);
}
static unsigned int ipv6_conntrack_local(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
return nf_conntrack_in(skb, state);
}
static const struct nf_hook_ops ipv6_conntrack_ops[] = {
{
.hook = ipv6_conntrack_in,
.pf = NFPROTO_IPV6,
.hooknum = NF_INET_PRE_ROUTING,
.priority = NF_IP6_PRI_CONNTRACK,
},
{
.hook = ipv6_conntrack_local,
.pf = NFPROTO_IPV6,
.hooknum = NF_INET_LOCAL_OUT,
.priority = NF_IP6_PRI_CONNTRACK,
},
{
.hook = nf_confirm,
.pf = NFPROTO_IPV6,
.hooknum = NF_INET_POST_ROUTING,
.priority = NF_IP6_PRI_LAST,
},
{
.hook = nf_confirm,
.pf = NFPROTO_IPV6,
.hooknum = NF_INET_LOCAL_IN,
.priority = NF_IP6_PRI_LAST - 1,
},
};
#endif
static int nf_ct_tcp_fixup(struct nf_conn *ct, void *_nfproto)
{
u8 nfproto = (unsigned long)_nfproto;
if (nf_ct_l3num(ct) != nfproto)
return 0;
if (nf_ct_protonum(ct) == IPPROTO_TCP &&
ct->proto.tcp.state == TCP_CONNTRACK_ESTABLISHED) {
ct->proto.tcp.seen[0].td_maxwin = 0;
ct->proto.tcp.seen[1].td_maxwin = 0;
}
return 0;
}
static struct nf_ct_bridge_info *nf_ct_bridge_info;
static int nf_ct_netns_do_get(struct net *net, u8 nfproto)
{
struct nf_conntrack_net *cnet = nf_ct_pernet(net);
bool fixup_needed = false, retry = true;
int err = 0;
retry:
mutex_lock(&nf_ct_proto_mutex);
switch (nfproto) {
case NFPROTO_IPV4:
cnet->users4++;
if (cnet->users4 > 1)
goto out_unlock;
err = nf_defrag_ipv4_enable(net);
if (err) {
cnet->users4 = 0;
goto out_unlock;
}
err = nf_register_net_hooks(net, ipv4_conntrack_ops,
ARRAY_SIZE(ipv4_conntrack_ops));
if (err)
cnet->users4 = 0;
else
fixup_needed = true;
break;
#if IS_ENABLED(CONFIG_IPV6)
case NFPROTO_IPV6:
cnet->users6++;
if (cnet->users6 > 1)
goto out_unlock;
err = nf_defrag_ipv6_enable(net);
if (err < 0) {
cnet->users6 = 0;
goto out_unlock;
}
err = nf_register_net_hooks(net, ipv6_conntrack_ops,
ARRAY_SIZE(ipv6_conntrack_ops));
if (err)
cnet->users6 = 0;
else
fixup_needed = true;
break;
#endif
case NFPROTO_BRIDGE:
if (!nf_ct_bridge_info) {
if (!retry) {
err = -EPROTO;
goto out_unlock;
}
mutex_unlock(&nf_ct_proto_mutex);
request_module("nf_conntrack_bridge");
retry = false;
goto retry;
}
if (!try_module_get(nf_ct_bridge_info->me)) {
err = -EPROTO;
goto out_unlock;
}
cnet->users_bridge++;
if (cnet->users_bridge > 1)
goto out_unlock;
err = nf_register_net_hooks(net, nf_ct_bridge_info->ops,
nf_ct_bridge_info->ops_size);
if (err)
cnet->users_bridge = 0;
else
fixup_needed = true;
break;
default:
err = -EPROTO;
break;
}
out_unlock:
mutex_unlock(&nf_ct_proto_mutex);
if (fixup_needed) {
struct nf_ct_iter_data iter_data = {
.net = net,
.data = (void *)(unsigned long)nfproto,
};
nf_ct_iterate_cleanup_net(nf_ct_tcp_fixup, &iter_data);
}
return err;
}
static void nf_ct_netns_do_put(struct net *net, u8 nfproto)
{
struct nf_conntrack_net *cnet = nf_ct_pernet(net);
mutex_lock(&nf_ct_proto_mutex);
switch (nfproto) {
case NFPROTO_IPV4:
if (cnet->users4 && (--cnet->users4 == 0)) {
nf_unregister_net_hooks(net, ipv4_conntrack_ops,
ARRAY_SIZE(ipv4_conntrack_ops));
nf_defrag_ipv4_disable(net);
}
break;
#if IS_ENABLED(CONFIG_IPV6)
case NFPROTO_IPV6:
if (cnet->users6 && (--cnet->users6 == 0)) {
nf_unregister_net_hooks(net, ipv6_conntrack_ops,
ARRAY_SIZE(ipv6_conntrack_ops));
nf_defrag_ipv6_disable(net);
}
break;
#endif
case NFPROTO_BRIDGE:
if (!nf_ct_bridge_info)
break;
if (cnet->users_bridge && (--cnet->users_bridge == 0))
nf_unregister_net_hooks(net, nf_ct_bridge_info->ops,
nf_ct_bridge_info->ops_size);
module_put(nf_ct_bridge_info->me);
break;
}
mutex_unlock(&nf_ct_proto_mutex);
}
static int nf_ct_netns_inet_get(struct net *net)
{
int err;
err = nf_ct_netns_do_get(net, NFPROTO_IPV4);
#if IS_ENABLED(CONFIG_IPV6)
if (err < 0)
goto err1;
err = nf_ct_netns_do_get(net, NFPROTO_IPV6);
if (err < 0)
goto err2;
return err;
err2:
nf_ct_netns_put(net, NFPROTO_IPV4);
err1:
#endif
return err;
}
int nf_ct_netns_get(struct net *net, u8 nfproto)
{
int err;
switch (nfproto) {
case NFPROTO_INET:
err = nf_ct_netns_inet_get(net);
break;
case NFPROTO_BRIDGE:
err = nf_ct_netns_do_get(net, NFPROTO_BRIDGE);
if (err < 0)
return err;
err = nf_ct_netns_inet_get(net);
if (err < 0) {
nf_ct_netns_put(net, NFPROTO_BRIDGE);
return err;
}
break;
default:
err = nf_ct_netns_do_get(net, nfproto);
break;
}
return err;
}
EXPORT_SYMBOL_GPL(nf_ct_netns_get);
void nf_ct_netns_put(struct net *net, uint8_t nfproto)
{
switch (nfproto) {
case NFPROTO_BRIDGE:
nf_ct_netns_do_put(net, NFPROTO_BRIDGE);
fallthrough;
case NFPROTO_INET:
nf_ct_netns_do_put(net, NFPROTO_IPV4);
nf_ct_netns_do_put(net, NFPROTO_IPV6);
break;
default:
nf_ct_netns_do_put(net, nfproto);
break;
}
}
EXPORT_SYMBOL_GPL(nf_ct_netns_put);
void nf_ct_bridge_register(struct nf_ct_bridge_info *info)
{
WARN_ON(nf_ct_bridge_info);
mutex_lock(&nf_ct_proto_mutex);
nf_ct_bridge_info = info;
mutex_unlock(&nf_ct_proto_mutex);
}
EXPORT_SYMBOL_GPL(nf_ct_bridge_register);
void nf_ct_bridge_unregister(struct nf_ct_bridge_info *info)
{
WARN_ON(!nf_ct_bridge_info);
mutex_lock(&nf_ct_proto_mutex);
nf_ct_bridge_info = NULL;
mutex_unlock(&nf_ct_proto_mutex);
}
EXPORT_SYMBOL_GPL(nf_ct_bridge_unregister);
int nf_conntrack_proto_init(void)
{
int ret;
ret = nf_register_sockopt(&so_getorigdst);
if (ret < 0)
return ret;
#if IS_ENABLED(CONFIG_IPV6)
ret = nf_register_sockopt(&so_getorigdst6);
if (ret < 0)
goto cleanup_sockopt;
#endif
return ret;
#if IS_ENABLED(CONFIG_IPV6)
cleanup_sockopt:
nf_unregister_sockopt(&so_getorigdst);
#endif
return ret;
}
void nf_conntrack_proto_fini(void)
{
nf_unregister_sockopt(&so_getorigdst);
#if IS_ENABLED(CONFIG_IPV6)
nf_unregister_sockopt(&so_getorigdst6);
#endif
}
void nf_conntrack_proto_pernet_init(struct net *net)
{
nf_conntrack_generic_init_net(net);
nf_conntrack_udp_init_net(net);
nf_conntrack_tcp_init_net(net);
nf_conntrack_icmp_init_net(net);
#if IS_ENABLED(CONFIG_IPV6)
nf_conntrack_icmpv6_init_net(net);
#endif
#ifdef CONFIG_NF_CT_PROTO_DCCP
nf_conntrack_dccp_init_net(net);
#endif
#ifdef CONFIG_NF_CT_PROTO_SCTP
nf_conntrack_sctp_init_net(net);
#endif
#ifdef CONFIG_NF_CT_PROTO_GRE
nf_conntrack_gre_init_net(net);
#endif
}
module_param_call(hashsize, nf_conntrack_set_hashsize, param_get_uint,
&nf_conntrack_htable_size, 0600);
MODULE_ALIAS("ip_conntrack");
MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET));
MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET6));
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("IPv4 and IPv6 connection tracking");