462 lines
12 KiB
C
462 lines
12 KiB
C
|
|
/* (C) 1999-2001 Paul `Rusty' Russell
|
|
* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
|
|
* (C) 2006-2012 Patrick McHardy <kaber@trash.net>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*/
|
|
|
|
#include <linux/types.h>
|
|
#include <linux/ip.h>
|
|
#include <linux/netfilter.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 <linux/netfilter_ipv4.h>
|
|
#include <net/netfilter/nf_conntrack.h>
|
|
#include <net/netfilter/nf_conntrack_helper.h>
|
|
#include <net/netfilter/nf_conntrack_l4proto.h>
|
|
#include <net/netfilter/nf_conntrack_l3proto.h>
|
|
#include <net/netfilter/nf_conntrack_zones.h>
|
|
#include <net/netfilter/nf_conntrack_core.h>
|
|
#include <net/netfilter/nf_conntrack_seqadj.h>
|
|
#include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
|
|
#include <net/netfilter/nf_nat_helper.h>
|
|
#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
|
|
#include <net/netfilter/nf_log.h>
|
|
|
|
static int conntrack4_net_id __read_mostly;
|
|
static DEFINE_MUTEX(register_ipv4_hooks);
|
|
|
|
struct conntrack4_net {
|
|
unsigned int users;
|
|
};
|
|
|
|
static bool ipv4_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
|
|
struct nf_conntrack_tuple *tuple)
|
|
{
|
|
const __be32 *ap;
|
|
__be32 _addrs[2];
|
|
ap = skb_header_pointer(skb, nhoff + offsetof(struct iphdr, saddr),
|
|
sizeof(u_int32_t) * 2, _addrs);
|
|
if (ap == NULL)
|
|
return false;
|
|
|
|
tuple->src.u3.ip = ap[0];
|
|
tuple->dst.u3.ip = ap[1];
|
|
|
|
return true;
|
|
}
|
|
|
|
static bool ipv4_invert_tuple(struct nf_conntrack_tuple *tuple,
|
|
const struct nf_conntrack_tuple *orig)
|
|
{
|
|
tuple->src.u3.ip = orig->dst.u3.ip;
|
|
tuple->dst.u3.ip = orig->src.u3.ip;
|
|
|
|
return true;
|
|
}
|
|
|
|
static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
|
|
unsigned int *dataoff, u_int8_t *protonum)
|
|
{
|
|
const struct iphdr *iph;
|
|
struct iphdr _iph;
|
|
|
|
iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
|
|
if (iph == NULL)
|
|
return -NF_ACCEPT;
|
|
|
|
/* Conntrack defragments packets, we might still see fragments
|
|
* inside ICMP packets though. */
|
|
if (iph->frag_off & htons(IP_OFFSET))
|
|
return -NF_ACCEPT;
|
|
|
|
*dataoff = nhoff + (iph->ihl << 2);
|
|
*protonum = iph->protocol;
|
|
|
|
/* Check bogus IP headers */
|
|
if (*dataoff > skb->len) {
|
|
pr_debug("nf_conntrack_ipv4: bogus IPv4 packet: "
|
|
"nhoff %u, ihl %u, skblen %u\n",
|
|
nhoff, iph->ihl << 2, skb->len);
|
|
return -NF_ACCEPT;
|
|
}
|
|
|
|
return NF_ACCEPT;
|
|
}
|
|
|
|
static unsigned int ipv4_helper(void *priv,
|
|
struct sk_buff *skb,
|
|
const struct nf_hook_state *state)
|
|
{
|
|
struct nf_conn *ct;
|
|
enum ip_conntrack_info ctinfo;
|
|
const struct nf_conn_help *help;
|
|
const struct nf_conntrack_helper *helper;
|
|
|
|
/* This is where we call the helper: as the packet goes out. */
|
|
ct = nf_ct_get(skb, &ctinfo);
|
|
if (!ct || ctinfo == IP_CT_RELATED_REPLY)
|
|
return NF_ACCEPT;
|
|
|
|
help = nfct_help(ct);
|
|
if (!help)
|
|
return NF_ACCEPT;
|
|
|
|
/* rcu_read_lock()ed by nf_hook_thresh */
|
|
helper = rcu_dereference(help->helper);
|
|
if (!helper)
|
|
return NF_ACCEPT;
|
|
|
|
return helper->help(skb, skb_network_offset(skb) + ip_hdrlen(skb),
|
|
ct, ctinfo);
|
|
}
|
|
|
|
static unsigned int ipv4_confirm(void *priv,
|
|
struct sk_buff *skb,
|
|
const struct nf_hook_state *state)
|
|
{
|
|
struct nf_conn *ct;
|
|
enum ip_conntrack_info ctinfo;
|
|
|
|
ct = nf_ct_get(skb, &ctinfo);
|
|
if (!ct || ctinfo == IP_CT_RELATED_REPLY)
|
|
goto out;
|
|
|
|
/* adjust seqs for loopback traffic only in outgoing direction */
|
|
if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
|
|
!nf_is_loopback_packet(skb)) {
|
|
if (!nf_ct_seq_adjust(skb, ct, ctinfo, ip_hdrlen(skb))) {
|
|
NF_CT_STAT_INC_ATOMIC(nf_ct_net(ct), drop);
|
|
return NF_DROP;
|
|
}
|
|
}
|
|
out:
|
|
/* We've seen it coming out the other side: confirm it */
|
|
return nf_conntrack_confirm(skb);
|
|
}
|
|
|
|
static unsigned int ipv4_conntrack_in(void *priv,
|
|
struct sk_buff *skb,
|
|
const struct nf_hook_state *state)
|
|
{
|
|
return nf_conntrack_in(state->net, PF_INET, state->hook, skb);
|
|
}
|
|
|
|
static unsigned int ipv4_conntrack_local(void *priv,
|
|
struct sk_buff *skb,
|
|
const struct nf_hook_state *state)
|
|
{
|
|
/* root is playing with raw sockets. */
|
|
if (skb->len < sizeof(struct iphdr) ||
|
|
ip_hdrlen(skb) < sizeof(struct iphdr))
|
|
return NF_ACCEPT;
|
|
|
|
if (ip_is_fragment(ip_hdr(skb))) /* IP_NODEFRAG setsockopt set */
|
|
return NF_ACCEPT;
|
|
|
|
return nf_conntrack_in(state->net, PF_INET, state->hook, skb);
|
|
}
|
|
|
|
/* 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 = ipv4_helper,
|
|
.pf = NFPROTO_IPV4,
|
|
.hooknum = NF_INET_POST_ROUTING,
|
|
.priority = NF_IP_PRI_CONNTRACK_HELPER,
|
|
},
|
|
{
|
|
.hook = ipv4_confirm,
|
|
.pf = NFPROTO_IPV4,
|
|
.hooknum = NF_INET_POST_ROUTING,
|
|
.priority = NF_IP_PRI_CONNTRACK_CONFIRM,
|
|
},
|
|
{
|
|
.hook = ipv4_helper,
|
|
.pf = NFPROTO_IPV4,
|
|
.hooknum = NF_INET_LOCAL_IN,
|
|
.priority = NF_IP_PRI_CONNTRACK_HELPER,
|
|
},
|
|
{
|
|
.hook = ipv4_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));
|
|
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;
|
|
|
|
/* We only do TCP and SCTP at the moment: is there a better way? */
|
|
if (sk->sk_protocol != IPPROTO_TCP && sk->sk_protocol != IPPROTO_SCTP) {
|
|
pr_debug("SO_ORIGINAL_DST: Not a TCP/SCTP socket\n");
|
|
return -ENOPROTOOPT;
|
|
}
|
|
|
|
if ((unsigned int) *len < sizeof(struct sockaddr_in)) {
|
|
pr_debug("SO_ORIGINAL_DST: len %d not %zu\n",
|
|
*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));
|
|
|
|
pr_debug("SO_ORIGINAL_DST: %pI4 %u\n",
|
|
&sin.sin_addr.s_addr, ntohs(sin.sin_port));
|
|
nf_ct_put(ct);
|
|
if (copy_to_user(user, &sin, sizeof(sin)) != 0)
|
|
return -EFAULT;
|
|
else
|
|
return 0;
|
|
}
|
|
pr_debug("SO_ORIGINAL_DST: Can't find %pI4/%u-%pI4/%u.\n",
|
|
&tuple.src.u3.ip, ntohs(tuple.src.u.tcp.port),
|
|
&tuple.dst.u3.ip, ntohs(tuple.dst.u.tcp.port));
|
|
return -ENOENT;
|
|
}
|
|
|
|
#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
|
|
|
|
#include <linux/netfilter/nfnetlink.h>
|
|
#include <linux/netfilter/nfnetlink_conntrack.h>
|
|
|
|
static int ipv4_tuple_to_nlattr(struct sk_buff *skb,
|
|
const struct nf_conntrack_tuple *tuple)
|
|
{
|
|
if (nla_put_in_addr(skb, CTA_IP_V4_SRC, tuple->src.u3.ip) ||
|
|
nla_put_in_addr(skb, CTA_IP_V4_DST, tuple->dst.u3.ip))
|
|
goto nla_put_failure;
|
|
return 0;
|
|
|
|
nla_put_failure:
|
|
return -1;
|
|
}
|
|
|
|
static const struct nla_policy ipv4_nla_policy[CTA_IP_MAX+1] = {
|
|
[CTA_IP_V4_SRC] = { .type = NLA_U32 },
|
|
[CTA_IP_V4_DST] = { .type = NLA_U32 },
|
|
};
|
|
|
|
static int ipv4_nlattr_to_tuple(struct nlattr *tb[],
|
|
struct nf_conntrack_tuple *t)
|
|
{
|
|
if (!tb[CTA_IP_V4_SRC] || !tb[CTA_IP_V4_DST])
|
|
return -EINVAL;
|
|
|
|
t->src.u3.ip = nla_get_in_addr(tb[CTA_IP_V4_SRC]);
|
|
t->dst.u3.ip = nla_get_in_addr(tb[CTA_IP_V4_DST]);
|
|
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
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,
|
|
};
|
|
|
|
static int ipv4_hooks_register(struct net *net)
|
|
{
|
|
struct conntrack4_net *cnet = net_generic(net, conntrack4_net_id);
|
|
int err = 0;
|
|
|
|
mutex_lock(®ister_ipv4_hooks);
|
|
|
|
cnet->users++;
|
|
if (cnet->users > 1)
|
|
goto out_unlock;
|
|
|
|
err = nf_defrag_ipv4_enable(net);
|
|
if (err) {
|
|
cnet->users = 0;
|
|
goto out_unlock;
|
|
}
|
|
|
|
err = nf_register_net_hooks(net, ipv4_conntrack_ops,
|
|
ARRAY_SIZE(ipv4_conntrack_ops));
|
|
|
|
if (err)
|
|
cnet->users = 0;
|
|
out_unlock:
|
|
mutex_unlock(®ister_ipv4_hooks);
|
|
return err;
|
|
}
|
|
|
|
static void ipv4_hooks_unregister(struct net *net)
|
|
{
|
|
struct conntrack4_net *cnet = net_generic(net, conntrack4_net_id);
|
|
|
|
mutex_lock(®ister_ipv4_hooks);
|
|
if (cnet->users && (--cnet->users == 0))
|
|
nf_unregister_net_hooks(net, ipv4_conntrack_ops,
|
|
ARRAY_SIZE(ipv4_conntrack_ops));
|
|
mutex_unlock(®ister_ipv4_hooks);
|
|
}
|
|
|
|
struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 __read_mostly = {
|
|
.l3proto = PF_INET,
|
|
.pkt_to_tuple = ipv4_pkt_to_tuple,
|
|
.invert_tuple = ipv4_invert_tuple,
|
|
.get_l4proto = ipv4_get_l4proto,
|
|
#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
|
|
.tuple_to_nlattr = ipv4_tuple_to_nlattr,
|
|
.nlattr_to_tuple = ipv4_nlattr_to_tuple,
|
|
.nla_policy = ipv4_nla_policy,
|
|
.nla_size = NLA_ALIGN(NLA_HDRLEN + sizeof(u32)) + /* CTA_IP_V4_SRC */
|
|
NLA_ALIGN(NLA_HDRLEN + sizeof(u32)), /* CTA_IP_V4_DST */
|
|
#endif
|
|
.net_ns_get = ipv4_hooks_register,
|
|
.net_ns_put = ipv4_hooks_unregister,
|
|
.me = THIS_MODULE,
|
|
};
|
|
|
|
module_param_call(hashsize, nf_conntrack_set_hashsize, param_get_uint,
|
|
&nf_conntrack_htable_size, 0600);
|
|
|
|
MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET));
|
|
MODULE_ALIAS("ip_conntrack");
|
|
MODULE_LICENSE("GPL");
|
|
|
|
static struct nf_conntrack_l4proto *builtin_l4proto4[] = {
|
|
&nf_conntrack_l4proto_tcp4,
|
|
&nf_conntrack_l4proto_udp4,
|
|
&nf_conntrack_l4proto_icmp,
|
|
#ifdef CONFIG_NF_CT_PROTO_DCCP
|
|
&nf_conntrack_l4proto_dccp4,
|
|
#endif
|
|
#ifdef CONFIG_NF_CT_PROTO_SCTP
|
|
&nf_conntrack_l4proto_sctp4,
|
|
#endif
|
|
#ifdef CONFIG_NF_CT_PROTO_UDPLITE
|
|
&nf_conntrack_l4proto_udplite4,
|
|
#endif
|
|
};
|
|
|
|
static int ipv4_net_init(struct net *net)
|
|
{
|
|
return nf_ct_l4proto_pernet_register(net, builtin_l4proto4,
|
|
ARRAY_SIZE(builtin_l4proto4));
|
|
}
|
|
|
|
static void ipv4_net_exit(struct net *net)
|
|
{
|
|
nf_ct_l4proto_pernet_unregister(net, builtin_l4proto4,
|
|
ARRAY_SIZE(builtin_l4proto4));
|
|
}
|
|
|
|
static struct pernet_operations ipv4_net_ops = {
|
|
.init = ipv4_net_init,
|
|
.exit = ipv4_net_exit,
|
|
.id = &conntrack4_net_id,
|
|
.size = sizeof(struct conntrack4_net),
|
|
};
|
|
|
|
static int __init nf_conntrack_l3proto_ipv4_init(void)
|
|
{
|
|
int ret = 0;
|
|
|
|
need_conntrack();
|
|
|
|
#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
|
|
if (WARN_ON(nla_policy_len(ipv4_nla_policy, CTA_IP_MAX + 1) !=
|
|
nf_conntrack_l3proto_ipv4.nla_size))
|
|
return -EINVAL;
|
|
#endif
|
|
ret = nf_register_sockopt(&so_getorigdst);
|
|
if (ret < 0) {
|
|
pr_err("Unable to register netfilter socket option\n");
|
|
return ret;
|
|
}
|
|
|
|
ret = register_pernet_subsys(&ipv4_net_ops);
|
|
if (ret < 0) {
|
|
pr_err("nf_conntrack_ipv4: can't register pernet ops\n");
|
|
goto cleanup_sockopt;
|
|
}
|
|
|
|
ret = nf_ct_l4proto_register(builtin_l4proto4,
|
|
ARRAY_SIZE(builtin_l4proto4));
|
|
if (ret < 0)
|
|
goto cleanup_pernet;
|
|
|
|
ret = nf_ct_l3proto_register(&nf_conntrack_l3proto_ipv4);
|
|
if (ret < 0) {
|
|
pr_err("nf_conntrack_ipv4: can't register ipv4 proto.\n");
|
|
goto cleanup_l4proto;
|
|
}
|
|
|
|
return ret;
|
|
cleanup_l4proto:
|
|
nf_ct_l4proto_unregister(builtin_l4proto4,
|
|
ARRAY_SIZE(builtin_l4proto4));
|
|
cleanup_pernet:
|
|
unregister_pernet_subsys(&ipv4_net_ops);
|
|
cleanup_sockopt:
|
|
nf_unregister_sockopt(&so_getorigdst);
|
|
return ret;
|
|
}
|
|
|
|
static void __exit nf_conntrack_l3proto_ipv4_fini(void)
|
|
{
|
|
synchronize_net();
|
|
nf_ct_l3proto_unregister(&nf_conntrack_l3proto_ipv4);
|
|
nf_ct_l4proto_unregister(builtin_l4proto4,
|
|
ARRAY_SIZE(builtin_l4proto4));
|
|
unregister_pernet_subsys(&ipv4_net_ops);
|
|
nf_unregister_sockopt(&so_getorigdst);
|
|
}
|
|
|
|
module_init(nf_conntrack_l3proto_ipv4_init);
|
|
module_exit(nf_conntrack_l3proto_ipv4_fini);
|