redonkable/alistair23-linux
redonkable/alistair23-linux
1
0
Fork 0
Code Releases Activity
alistair23-linux/net/netfilter/xt_conntrack.c
Florian Westphal cc41c84b7e netfilter: kill the fake untracked conntrack objects 
resurrect an old patch from Pablo Neira to remove the untracked objects.

Currently, there are four possible states of an skb wrt. conntrack.

1. No conntrack attached, ct is NULL.
2. Normal (kmem cache allocated) ct attached.
3. a template (kmalloc'd), not in any hash tables at any point in time
4. the 'untracked' conntrack, a percpu nf_conn object, tagged via
   IPS_UNTRACKED_BIT in ct->status.

Untracked is supposed to be identical to case 1.  It exists only
so users can check

-m conntrack --ctstate UNTRACKED vs.
-m conntrack --ctstate INVALID

e.g. attempts to set connmark on INVALID or UNTRACKED conntracks is
supposed to be a no-op.

Thus currently we need to check
 ct == NULL || nf_ct_is_untracked(ct)

in a lot of places in order to avoid altering untracked objects.

The other consequence of the percpu untracked object is that all
-j NOTRACK (and, later, kfree_skb of such skbs) result in an atomic op
(inc/dec the untracked conntracks refcount).

This adds a new kernel-private ctinfo state, IP_CT_UNTRACKED, to
make the distinction instead.

The (few) places that care about packet invalid (ct is NULL) vs.
packet untracked now need to test ct == NULL vs. ctinfo == IP_CT_UNTRACKED,
but all other places can omit the nf_ct_is_untracked() check.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2017-04-15 11:47:57 +02:00

331 lines
9.6 KiB
C
Raw Blame History

/*
* xt_conntrack - Netfilter module to match connection tracking
* information. (Superset of Rusty's minimalistic state match.)
*
* (C) 2001 Marc Boucher (marc@mbsi.ca).
* (C) 2006-2012 Patrick McHardy <kaber@trash.net>
* Copyright © CC Computer Consultants GmbH, 2007 - 2008
*
* 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.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/skbuff.h>
#include <net/ipv6.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_conntrack.h>
#include <net/netfilter/nf_conntrack.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
MODULE_DESCRIPTION("Xtables: connection tracking state match");
MODULE_ALIAS("ipt_conntrack");
MODULE_ALIAS("ip6t_conntrack");
static bool
conntrack_addrcmp(const union nf_inet_addr *kaddr,
const union nf_inet_addr *uaddr,
const union nf_inet_addr *umask, unsigned int l3proto)
{
if (l3proto == NFPROTO_IPV4)
return ((kaddr->ip ^ uaddr->ip) & umask->ip) == 0;
else if (l3proto == NFPROTO_IPV6)
return ipv6_masked_addr_cmp(&kaddr->in6, &umask->in6,
&uaddr->in6) == 0;
else
return false;
}
static inline bool
conntrack_mt_origsrc(const struct nf_conn *ct,
const struct xt_conntrack_mtinfo2 *info,
u_int8_t family)
{
return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3,
&info->origsrc_addr, &info->origsrc_mask, family);
}
static inline bool
conntrack_mt_origdst(const struct nf_conn *ct,
const struct xt_conntrack_mtinfo2 *info,
u_int8_t family)
{
return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3,
&info->origdst_addr, &info->origdst_mask, family);
}
static inline bool
conntrack_mt_replsrc(const struct nf_conn *ct,
const struct xt_conntrack_mtinfo2 *info,
u_int8_t family)
{
return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3,
&info->replsrc_addr, &info->replsrc_mask, family);
}
static inline bool
conntrack_mt_repldst(const struct nf_conn *ct,
const struct xt_conntrack_mtinfo2 *info,
u_int8_t family)
{
return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3,
&info->repldst_addr, &info->repldst_mask, family);
}
static inline bool
ct_proto_port_check(const struct xt_conntrack_mtinfo2 *info,
const struct nf_conn *ct)
{
const struct nf_conntrack_tuple *tuple;
tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
if ((info->match_flags & XT_CONNTRACK_PROTO) &&
(nf_ct_protonum(ct) == info->l4proto) ^
!(info->invert_flags & XT_CONNTRACK_PROTO))
return false;
/* Shortcut to match all recognized protocols by using ->src.all. */
if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
(tuple->src.u.all == info->origsrc_port) ^
!(info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
return false;
if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
(tuple->dst.u.all == info->origdst_port) ^
!(info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
return false;
tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
(tuple->src.u.all == info->replsrc_port) ^
!(info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
return false;
if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
(tuple->dst.u.all == info->repldst_port) ^
!(info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
return false;
return true;
}
static inline bool
port_match(u16 min, u16 max, u16 port, bool invert)
{
return (port >= min && port <= max) ^ invert;
}
static inline bool
ct_proto_port_check_v3(const struct xt_conntrack_mtinfo3 *info,
const struct nf_conn *ct)
{
const struct nf_conntrack_tuple *tuple;
tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
if ((info->match_flags & XT_CONNTRACK_PROTO) &&
(nf_ct_protonum(ct) == info->l4proto) ^
!(info->invert_flags & XT_CONNTRACK_PROTO))
return false;
/* Shortcut to match all recognized protocols by using ->src.all. */
if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
!port_match(info->origsrc_port, info->origsrc_port_high,
ntohs(tuple->src.u.all),
info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
return false;
if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
!port_match(info->origdst_port, info->origdst_port_high,
ntohs(tuple->dst.u.all),
info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
return false;
tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
!port_match(info->replsrc_port, info->replsrc_port_high,
ntohs(tuple->src.u.all),
info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
return false;
if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
!port_match(info->repldst_port, info->repldst_port_high,
ntohs(tuple->dst.u.all),
info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
return false;
return true;
}
static bool
conntrack_mt(const struct sk_buff *skb, struct xt_action_param *par,
u16 state_mask, u16 status_mask)
{
const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
enum ip_conntrack_info ctinfo;
const struct nf_conn *ct;
unsigned int statebit;
ct = nf_ct_get(skb, &ctinfo);
if (ct)
statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
else if (ctinfo == IP_CT_UNTRACKED)
statebit = XT_CONNTRACK_STATE_UNTRACKED;
else
statebit = XT_CONNTRACK_STATE_INVALID;
if (info->match_flags & XT_CONNTRACK_STATE) {
if (ct != NULL) {
if (test_bit(IPS_SRC_NAT_BIT, &ct->status))
statebit |= XT_CONNTRACK_STATE_SNAT;
if (test_bit(IPS_DST_NAT_BIT, &ct->status))
statebit |= XT_CONNTRACK_STATE_DNAT;
}
if (!!(state_mask & statebit) ^
!(info->invert_flags & XT_CONNTRACK_STATE))
return false;
}
if (ct == NULL)
return info->match_flags & XT_CONNTRACK_STATE;
if ((info->match_flags & XT_CONNTRACK_DIRECTION) &&
(CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) ^
!(info->invert_flags & XT_CONNTRACK_DIRECTION))
return false;
if (info->match_flags & XT_CONNTRACK_ORIGSRC)
if (conntrack_mt_origsrc(ct, info, xt_family(par)) ^
!(info->invert_flags & XT_CONNTRACK_ORIGSRC))
return false;
if (info->match_flags & XT_CONNTRACK_ORIGDST)
if (conntrack_mt_origdst(ct, info, xt_family(par)) ^
!(info->invert_flags & XT_CONNTRACK_ORIGDST))
return false;
if (info->match_flags & XT_CONNTRACK_REPLSRC)
if (conntrack_mt_replsrc(ct, info, xt_family(par)) ^
!(info->invert_flags & XT_CONNTRACK_REPLSRC))
return false;
if (info->match_flags & XT_CONNTRACK_REPLDST)
if (conntrack_mt_repldst(ct, info, xt_family(par)) ^
!(info->invert_flags & XT_CONNTRACK_REPLDST))
return false;
if (par->match->revision != 3) {
if (!ct_proto_port_check(info, ct))
return false;
} else {
if (!ct_proto_port_check_v3(par->matchinfo, ct))
return false;
}
if ((info->match_flags & XT_CONNTRACK_STATUS) &&
(!!(status_mask & ct->status) ^
!(info->invert_flags & XT_CONNTRACK_STATUS)))
return false;
if (info->match_flags & XT_CONNTRACK_EXPIRES) {
unsigned long expires = nf_ct_expires(ct) / HZ;
if ((expires >= info->expires_min &&
expires <= info->expires_max) ^
!(info->invert_flags & XT_CONNTRACK_EXPIRES))
return false;
}
return true;
}
static bool
conntrack_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_conntrack_mtinfo1 *info = par->matchinfo;
return conntrack_mt(skb, par, info->state_mask, info->status_mask);
}
static bool
conntrack_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
return conntrack_mt(skb, par, info->state_mask, info->status_mask);
}
static bool
conntrack_mt_v3(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_conntrack_mtinfo3 *info = par->matchinfo;
return conntrack_mt(skb, par, info->state_mask, info->status_mask);
}
static int conntrack_mt_check(const struct xt_mtchk_param *par)
{
int ret;
ret = nf_ct_netns_get(par->net, par->family);
if (ret < 0)
pr_info("cannot load conntrack support for proto=%u\n",
par->family);
return ret;
}
static void conntrack_mt_destroy(const struct xt_mtdtor_param *par)
{
nf_ct_netns_put(par->net, par->family);
}
static struct xt_match conntrack_mt_reg[] __read_mostly = {
{
.name = "conntrack",
.revision = 1,
.family = NFPROTO_UNSPEC,
.matchsize = sizeof(struct xt_conntrack_mtinfo1),
.match = conntrack_mt_v1,
.checkentry = conntrack_mt_check,
.destroy = conntrack_mt_destroy,
.me = THIS_MODULE,
},
{
.name = "conntrack",
.revision = 2,
.family = NFPROTO_UNSPEC,
.matchsize = sizeof(struct xt_conntrack_mtinfo2),
.match = conntrack_mt_v2,
.checkentry = conntrack_mt_check,
.destroy = conntrack_mt_destroy,
.me = THIS_MODULE,
},
{
.name = "conntrack",
.revision = 3,
.family = NFPROTO_UNSPEC,
.matchsize = sizeof(struct xt_conntrack_mtinfo3),
.match = conntrack_mt_v3,
.checkentry = conntrack_mt_check,
.destroy = conntrack_mt_destroy,
.me = THIS_MODULE,
},
};
static int __init conntrack_mt_init(void)
{
return xt_register_matches(conntrack_mt_reg,
ARRAY_SIZE(conntrack_mt_reg));
}
static void __exit conntrack_mt_exit(void)
{
xt_unregister_matches(conntrack_mt_reg, ARRAY_SIZE(conntrack_mt_reg));
}
module_init(conntrack_mt_init);
module_exit(conntrack_mt_exit);
View git blame Copy permalink