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netfilter: add user-space connection tracking helper infrastructure

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There are good reasons to supports helpers in user-space instead:

* Rapid connection tracking helper development, as developing code
  in user-space is usually faster.

* Reliability: A buggy helper does not crash the kernel. Moreover,
  we can monitor the helper process and restart it in case of problems.

* Security: Avoid complex string matching and mangling in kernel-space
  running in privileged mode. Going further, we can even think about
  running user-space helpers as a non-root process.

* Extensibility: It allows the development of very specific helpers (most
  likely non-standard proprietary protocols) that are very likely not to be
  accepted for mainline inclusion in the form of kernel-space connection
  tracking helpers.

This patch adds the infrastructure to allow the implementation of
user-space conntrack helpers by means of the new nfnetlink subsystem
`nfnetlink_cthelper' and the existing queueing infrastructure
(nfnetlink_queue).

I had to add the new hook NF_IP6_PRI_CONNTRACK_HELPER to register
ipv[4|6]_helper which results from splitting ipv[4|6]_confirm into
two pieces. This change is required not to break NAT sequence
adjustment and conntrack confirmation for traffic that is enqueued
to our user-space conntrack helpers.

Basic operation, in a few steps:

1) Register user-space helper by means of `nfct':

 nfct helper add ftp inet tcp

 [ It must be a valid existing helper supported by conntrack-tools ]

2) Add rules to enable the FTP user-space helper which is
   used to track traffic going to TCP port 21.

For locally generated packets:

 iptables -I OUTPUT -t raw -p tcp --dport 21 -j CT --helper ftp

For non-locally generated packets:

 iptables -I PREROUTING -t raw -p tcp --dport 21 -j CT --helper ftp

3) Run the test conntrackd in helper mode (see example files under
   doc/helper/conntrackd.conf

 conntrackd

4) Generate FTP traffic going, if everything is OK, then conntrackd
   should create expectations (you can check that with `conntrack':

 conntrack -E expect

    [NEW] 301 proto=6 src=192.168.1.136 dst=130.89.148.12 sport=0 dport=54037 mask-src=255.255.255.255 mask-dst=255.255.255.255 sport=0 dport=65535 master-src=192.168.1.136 master-dst=130.89.148.12 sport=57127 dport=21 class=0 helper=ftp
[DESTROY] 301 proto=6 src=192.168.1.136 dst=130.89.148.12 sport=0 dport=54037 mask-src=255.255.255.255 mask-dst=255.255.255.255 sport=0 dport=65535 master-src=192.168.1.136 master-dst=130.89.148.12 sport=57127 dport=21 class=0 helper=ftp

This confirms that our test helper is receiving packets including the
conntrack information, and adding expectations in kernel-space.

The user-space helper can also store its private tracking information
in the conntrack structure in the kernel via the CTA_HELP_INFO. The
kernel will consider this a binary blob whose layout is unknown. This
information will be included in the information that is transfered
to user-space via glue code that integrates nfnetlink_queue and
ctnetlink.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Pablo Neira Ayuso 2012-05-13 21:44:54 +02:00
parent ae243bee39
commit 12f7a50533
12 changed files with 839 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/netfilter/Kbuild
View File

@ -10,6 +10,7 @@ header-y += nfnetlink.h
header-y += nfnetlink_acct.h
header-y += nfnetlink_compat.h
header-y += nfnetlink_conntrack.h
header-y += nfnetlink_cthelper.h
header-y += nfnetlink_cttimeout.h
header-y += nfnetlink_log.h
header-y += nfnetlink_queue.h

3
include/linux/netfilter/nfnetlink.h
View File

@ -50,7 +50,8 @@ struct nfgenmsg {
#define NFNL_SUBSYS_IPSET 6
#define NFNL_SUBSYS_ACCT 7
#define NFNL_SUBSYS_CTNETLINK_TIMEOUT 8
#define NFNL_SUBSYS_COUNT 9
#define NFNL_SUBSYS_CTHELPER 9
#define NFNL_SUBSYS_COUNT 10
#ifdef __KERNEL__

55
include/linux/netfilter/nfnetlink_cthelper.h Normal file
View File

@ -0,0 +1,55 @@
#ifndef _NFNL_CTHELPER_H_
#define _NFNL_CTHELPER_H_
#define NFCT_HELPER_STATUS_DISABLED 0
#define NFCT_HELPER_STATUS_ENABLED 1
enum nfnl_acct_msg_types {
NFNL_MSG_CTHELPER_NEW,
NFNL_MSG_CTHELPER_GET,
NFNL_MSG_CTHELPER_DEL,
NFNL_MSG_CTHELPER_MAX
};
enum nfnl_cthelper_type {
NFCTH_UNSPEC,
NFCTH_NAME,
NFCTH_TUPLE,
NFCTH_QUEUE_NUM,
NFCTH_POLICY,
NFCTH_PRIV_DATA_LEN,
NFCTH_STATUS,
__NFCTH_MAX
};
#define NFCTH_MAX (__NFCTH_MAX - 1)
enum nfnl_cthelper_policy_type {
NFCTH_POLICY_SET_UNSPEC,
NFCTH_POLICY_SET_NUM,
NFCTH_POLICY_SET,
NFCTH_POLICY_SET1 = NFCTH_POLICY_SET,
NFCTH_POLICY_SET2,
NFCTH_POLICY_SET3,
NFCTH_POLICY_SET4,
__NFCTH_POLICY_SET_MAX
};
#define NFCTH_POLICY_SET_MAX (__NFCTH_POLICY_SET_MAX - 1)
enum nfnl_cthelper_pol_type {
NFCTH_POLICY_UNSPEC,
NFCTH_POLICY_NAME,
NFCTH_POLICY_EXPECT_MAX,
NFCTH_POLICY_EXPECT_TIMEOUT,
__NFCTH_POLICY_MAX
};
#define NFCTH_POLICY_MAX (__NFCTH_POLICY_MAX - 1)
enum nfnl_cthelper_tuple_type {
NFCTH_TUPLE_UNSPEC,
NFCTH_TUPLE_L3PROTONUM,
NFCTH_TUPLE_L4PROTONUM,
__NFCTH_TUPLE_MAX,
};
#define NFCTH_TUPLE_MAX (__NFCTH_TUPLE_MAX - 1)
#endif /* _NFNL_CTHELPER_H */

1
include/linux/netfilter_ipv4.h
View File

@ -66,6 +66,7 @@ enum nf_ip_hook_priorities {
NF_IP_PRI_SECURITY = 50,
NF_IP_PRI_NAT_SRC = 100,
NF_IP_PRI_SELINUX_LAST = 225,
NF_IP_PRI_CONNTRACK_HELPER = 300,
NF_IP_PRI_CONNTRACK_CONFIRM = INT_MAX,
NF_IP_PRI_LAST = INT_MAX,
};

1
include/linux/netfilter_ipv6.h
View File

@ -71,6 +71,7 @@ enum nf_ip6_hook_priorities {
NF_IP6_PRI_SECURITY = 50,
NF_IP6_PRI_NAT_SRC = 100,
NF_IP6_PRI_SELINUX_LAST = 225,
NF_IP6_PRI_CONNTRACK_HELPER = 300,
NF_IP6_PRI_LAST = INT_MAX,
};

11
include/net/netfilter/nf_conntrack_helper.h
View File

@ -15,6 +15,11 @@
struct module;
enum nf_ct_helper_flags {
NF_CT_HELPER_F_USERSPACE = (1 << 0),
NF_CT_HELPER_F_CONFIGURED = (1 << 1),
};
#define NF_CT_HELPER_NAME_LEN 16
struct nf_conntrack_helper {
@ -42,6 +47,9 @@ struct nf_conntrack_helper {
int (*from_nlattr)(struct nlattr *attr, struct nf_conn *ct);
int (*to_nlattr)(struct sk_buff *skb, const struct nf_conn *ct);
unsigned int expect_class_max;
unsigned int flags;
unsigned int queue_num; /* For user-space helpers. */
};
extern struct nf_conntrack_helper *
@ -96,4 +104,7 @@ nf_ct_helper_expectfn_find_by_name(const char *name);
struct nf_ct_helper_expectfn *
nf_ct_helper_expectfn_find_by_symbol(const void *symbol);
extern struct hlist_head *nf_ct_helper_hash;
extern unsigned int nf_ct_helper_hsize;
#endif /*_NF_CONNTRACK_HELPER_H*/

48
net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
View File

@ -95,11 +95,11 @@ static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
return NF_ACCEPT;
}
static unsigned int ipv4_confirm(unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
static unsigned int ipv4_helper(unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
@ -110,24 +110,38 @@ static unsigned int ipv4_confirm(unsigned int hooknum,
/* 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)
goto out;
return NF_ACCEPT;
help = nfct_help(ct);
if (!help)
goto out;
return NF_ACCEPT;
/* rcu_read_lock()ed by nf_hook_slow */
helper = rcu_dereference(help->helper);
if (!helper)
goto out;
return NF_ACCEPT;
ret = helper->help(skb, skb_network_offset(skb) + ip_hdrlen(skb),
ct, ctinfo);
if (ret != NF_ACCEPT) {
if (ret != NF_ACCEPT && (ret & NF_VERDICT_MASK) != NF_QUEUE) {
nf_log_packet(NFPROTO_IPV4, hooknum, skb, in, out, NULL,
"nf_ct_%s: dropping packet", helper->name);
return ret;
}
return ret;
}
static unsigned int ipv4_confirm(unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
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) &&
@ -184,6 +198,13 @@ static struct nf_hook_ops ipv4_conntrack_ops[] __read_mostly = {
.hooknum = NF_INET_LOCAL_OUT,
.priority = NF_IP_PRI_CONNTRACK,
},
{
.hook = ipv4_helper,
.owner = THIS_MODULE,
.pf = NFPROTO_IPV4,
.hooknum = NF_INET_POST_ROUTING,
.priority = NF_IP_PRI_CONNTRACK_HELPER,
},
{
.hook = ipv4_confirm,
.owner = THIS_MODULE,
@ -191,6 +212,13 @@ static struct nf_hook_ops ipv4_conntrack_ops[] __read_mostly = {
.hooknum = NF_INET_POST_ROUTING,
.priority = NF_IP_PRI_CONNTRACK_CONFIRM,
},
{
.hook = ipv4_helper,
.owner = THIS_MODULE,
.pf = NFPROTO_IPV4,
.hooknum = NF_INET_LOCAL_IN,
.priority = NF_IP_PRI_CONNTRACK_HELPER,
},
{
.hook = ipv4_confirm,
.owner = THIS_MODULE,

43
net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
View File

@ -143,11 +143,11 @@ static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
return NF_ACCEPT;
}
static unsigned int ipv6_confirm(unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
static unsigned int ipv6_helper(unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct nf_conn *ct;
const struct nf_conn_help *help;
@ -161,15 +161,15 @@ static unsigned int ipv6_confirm(unsigned int hooknum,
/* 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)
goto out;
return NF_ACCEPT;
help = nfct_help(ct);
if (!help)
goto out;
return NF_ACCEPT;
/* rcu_read_lock()ed by nf_hook_slow */
helper = rcu_dereference(help->helper);
if (!helper)
goto out;
return NF_ACCEPT;
protoff = nf_ct_ipv6_skip_exthdr(skb, extoff, &pnum,
skb->len - extoff);
@ -179,12 +179,19 @@ static unsigned int ipv6_confirm(unsigned int hooknum,
}
ret = helper->help(skb, protoff, ct, ctinfo);
if (ret != NF_ACCEPT) {
if (ret != NF_ACCEPT && (ret & NF_VERDICT_MASK) != NF_QUEUE) {
nf_log_packet(NFPROTO_IPV6, hooknum, skb, in, out, NULL,
"nf_ct_%s: dropping packet", helper->name);
return ret;
}
out:
return ret;
}
static unsigned int ipv6_confirm(unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
/* We've seen it coming out the other side: confirm it */
return nf_conntrack_confirm(skb);
}
@ -253,6 +260,13 @@ static struct nf_hook_ops ipv6_conntrack_ops[] __read_mostly = {
.hooknum = NF_INET_LOCAL_OUT,
.priority = NF_IP6_PRI_CONNTRACK,
},
{
.hook = ipv6_helper,
.owner = THIS_MODULE,
.pf = NFPROTO_IPV6,
.hooknum = NF_INET_POST_ROUTING,
.priority = NF_IP6_PRI_CONNTRACK_HELPER,
},
{
.hook = ipv6_confirm,
.owner = THIS_MODULE,
@ -260,6 +274,13 @@ static struct nf_hook_ops ipv6_conntrack_ops[] __read_mostly = {
.hooknum = NF_INET_POST_ROUTING,
.priority = NF_IP6_PRI_LAST,
},
{
.hook = ipv6_helper,
.owner = THIS_MODULE,
.pf = NFPROTO_IPV6,
.hooknum = NF_INET_LOCAL_IN,
.priority = NF_IP6_PRI_CONNTRACK_HELPER,
},
{
.hook = ipv6_confirm,
.owner = THIS_MODULE,

8
net/netfilter/Kconfig
View File

@ -12,6 +12,14 @@ tristate "Netfilter NFACCT over NFNETLINK interface"
If this option is enabled, the kernel will include support
for extended accounting via NFNETLINK.
config NETFILTER_NETLINK_CTHELPER
tristate "Netfilter CTHELPER over NFNETLINK interface"
depends on NETFILTER_ADVANCED
select NETFILTER_NETLINK
help
If this option is enabled, the kernel will include support
for user-space connection tracking helpers via NFNETLINK.
config NETFILTER_NETLINK_QUEUE
tristate "Netfilter NFQUEUE over NFNETLINK interface"
depends on NETFILTER_ADVANCED

1
net/netfilter/Makefile
View File

@ -9,6 +9,7 @@ obj-$(CONFIG_NETFILTER) = netfilter.o
obj-$(CONFIG_NETFILTER_NETLINK) += nfnetlink.o
obj-$(CONFIG_NETFILTER_NETLINK_ACCT) += nfnetlink_acct.o
obj-$(CONFIG_NETFILTER_NETLINK_CTHELPER) += nfnetlink_cthelper.o
obj-$(CONFIG_NETFILTER_NETLINK_QUEUE) += nfnetlink_queue.o
obj-$(CONFIG_NETFILTER_NETLINK_LOG) += nfnetlink_log.o

21
net/netfilter/nf_conntrack_helper.c
View File

@ -30,8 +30,10 @@
#include <net/netfilter/nf_conntrack_extend.h>
static DEFINE_MUTEX(nf_ct_helper_mutex);
static struct hlist_head *nf_ct_helper_hash __read_mostly;
static unsigned int nf_ct_helper_hsize __read_mostly;
struct hlist_head *nf_ct_helper_hash __read_mostly;
EXPORT_SYMBOL_GPL(nf_ct_helper_hash);
unsigned int nf_ct_helper_hsize __read_mostly;
EXPORT_SYMBOL_GPL(nf_ct_helper_hsize);
static unsigned int nf_ct_helper_count __read_mostly;
static bool nf_ct_auto_assign_helper __read_mostly = true;
@ -322,6 +324,9 @@ EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol);
int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
{
int ret = 0;
struct nf_conntrack_helper *cur;
struct hlist_node *n;
unsigned int h = helper_hash(&me->tuple);
BUG_ON(me->expect_policy == NULL);
@ -329,11 +334,19 @@ int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
mutex_lock(&nf_ct_helper_mutex);
hlist_for_each_entry(cur, n, &nf_ct_helper_hash[h], hnode) {
if (strncmp(cur->name, me->name, NF_CT_HELPER_NAME_LEN) == 0 &&
cur->tuple.src.l3num == me->tuple.src.l3num &&
cur->tuple.dst.protonum == me->tuple.dst.protonum) {
ret = -EEXIST;
goto out;
}
}
hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
nf_ct_helper_count++;
out:
mutex_unlock(&nf_ct_helper_mutex);
return 0;
return ret;
}
EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);

672
net/netfilter/nfnetlink_cthelper.c Normal file
View File

@ -0,0 +1,672 @@
/*
* (C) 2012 Pablo Neira Ayuso <pablo@netfilter.org>
*
* 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 (or any later at your option).
*
* This software has been sponsored by Vyatta Inc. <http://www.vyatta.com>
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/rculist.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/errno.h>
#include <net/netlink.h>
#include <net/sock.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_conntrack.h>
#include <linux/netfilter/nfnetlink_cthelper.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
MODULE_DESCRIPTION("nfnl_cthelper: User-space connection tracking helpers");
static int
nfnl_userspace_cthelper(struct sk_buff *skb, unsigned int protoff,
struct nf_conn *ct, enum ip_conntrack_info ctinfo)
{
const struct nf_conn_help *help;
struct nf_conntrack_helper *helper;
help = nfct_help(ct);
if (help == NULL)
return NF_DROP;
/* rcu_read_lock()ed by nf_hook_slow */
helper = rcu_dereference(help->helper);
if (helper == NULL)
return NF_DROP;
/* This is an user-space helper not yet configured, skip. */
if ((helper->flags &
(NF_CT_HELPER_F_USERSPACE | NF_CT_HELPER_F_CONFIGURED)) ==
NF_CT_HELPER_F_USERSPACE)
return NF_ACCEPT;
/* If the user-space helper is not available, don't block traffic. */
return NF_QUEUE_NR(helper->queue_num) | NF_VERDICT_FLAG_QUEUE_BYPASS;
}
static const struct nla_policy nfnl_cthelper_tuple_pol[NFCTH_TUPLE_MAX+1] = {
[NFCTH_TUPLE_L3PROTONUM] = { .type = NLA_U16, },
[NFCTH_TUPLE_L4PROTONUM] = { .type = NLA_U8, },
};
static int
nfnl_cthelper_parse_tuple(struct nf_conntrack_tuple *tuple,
const struct nlattr *attr)
{
struct nlattr *tb[NFCTH_TUPLE_MAX+1];
nla_parse_nested(tb, NFCTH_TUPLE_MAX, attr, nfnl_cthelper_tuple_pol);
if (!tb[NFCTH_TUPLE_L3PROTONUM] || !tb[NFCTH_TUPLE_L4PROTONUM])
return -EINVAL;
tuple->src.l3num = ntohs(nla_get_u16(tb[NFCTH_TUPLE_L3PROTONUM]));
tuple->dst.protonum = nla_get_u8(tb[NFCTH_TUPLE_L4PROTONUM]);
return 0;
}
static int
nfnl_cthelper_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
{
const struct nf_conn_help *help = nfct_help(ct);
if (help->helper->data_len == 0)
return -EINVAL;
memcpy(&help->data, nla_data(attr), help->helper->data_len);
return 0;
}
static int
nfnl_cthelper_to_nlattr(struct sk_buff *skb, const struct nf_conn *ct)
{
const struct nf_conn_help *help = nfct_help(ct);
if (help->helper->data_len &&
nla_put(skb, CTA_HELP_INFO, help->helper->data_len, &help->data))
goto nla_put_failure;
return 0;
nla_put_failure:
return -ENOSPC;
}
static const struct nla_policy nfnl_cthelper_expect_pol[NFCTH_POLICY_MAX+1] = {
[NFCTH_POLICY_NAME] = { .type = NLA_NUL_STRING,
.len = NF_CT_HELPER_NAME_LEN-1 },
[NFCTH_POLICY_EXPECT_MAX] = { .type = NLA_U32, },
[NFCTH_POLICY_EXPECT_TIMEOUT] = { .type = NLA_U32, },
};
static int
nfnl_cthelper_expect_policy(struct nf_conntrack_expect_policy *expect_policy,
const struct nlattr *attr)
{
struct nlattr *tb[NFCTH_POLICY_MAX+1];
nla_parse_nested(tb, NFCTH_POLICY_MAX, attr, nfnl_cthelper_expect_pol);
if (!tb[NFCTH_POLICY_NAME] ||
!tb[NFCTH_POLICY_EXPECT_MAX] ||
!tb[NFCTH_POLICY_EXPECT_TIMEOUT])
return -EINVAL;
strncpy(expect_policy->name,
nla_data(tb[NFCTH_POLICY_NAME]), NF_CT_HELPER_NAME_LEN);
expect_policy->max_expected =
ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
expect_policy->timeout =
ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
return 0;
}
static const struct nla_policy
nfnl_cthelper_expect_policy_set[NFCTH_POLICY_SET_MAX+1] = {
[NFCTH_POLICY_SET_NUM] = { .type = NLA_U32, },
};
static int
nfnl_cthelper_parse_expect_policy(struct nf_conntrack_helper *helper,
const struct nlattr *attr)
{
int i, ret;
struct nf_conntrack_expect_policy *expect_policy;
struct nlattr *tb[NFCTH_POLICY_SET_MAX+1];
nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
nfnl_cthelper_expect_policy_set);
if (!tb[NFCTH_POLICY_SET_NUM])
return -EINVAL;
helper->expect_class_max =
ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
if (helper->expect_class_max != 0 &&
helper->expect_class_max > NF_CT_MAX_EXPECT_CLASSES)
return -EOVERFLOW;
expect_policy = kzalloc(sizeof(struct nf_conntrack_expect_policy) *
helper->expect_class_max, GFP_KERNEL);
if (expect_policy == NULL)
return -ENOMEM;
for (i=0; i<helper->expect_class_max; i++) {
if (!tb[NFCTH_POLICY_SET+i])
goto err;
ret = nfnl_cthelper_expect_policy(&expect_policy[i],
tb[NFCTH_POLICY_SET+i]);
if (ret < 0)
goto err;
}
helper->expect_policy = expect_policy;
return 0;
err:
kfree(expect_policy);
return -EINVAL;
}
static int
nfnl_cthelper_create(const struct nlattr * const tb[],
struct nf_conntrack_tuple *tuple)
{
struct nf_conntrack_helper *helper;
int ret;
if (!tb[NFCTH_TUPLE] || !tb[NFCTH_POLICY] || !tb[NFCTH_PRIV_DATA_LEN])
return -EINVAL;
helper = kzalloc(sizeof(struct nf_conntrack_helper), GFP_KERNEL);
if (helper == NULL)
return -ENOMEM;
ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]);
if (ret < 0)
goto err;
strncpy(helper->name, nla_data(tb[NFCTH_NAME]), NF_CT_HELPER_NAME_LEN);
helper->data_len = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
helper->flags |= NF_CT_HELPER_F_USERSPACE;
memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));
helper->me = THIS_MODULE;
helper->help = nfnl_userspace_cthelper;
helper->from_nlattr = nfnl_cthelper_from_nlattr;
helper->to_nlattr = nfnl_cthelper_to_nlattr;
/* Default to queue number zero, this can be updated at any time. */
if (tb[NFCTH_QUEUE_NUM])
helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
if (tb[NFCTH_STATUS]) {
int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
switch(status) {
case NFCT_HELPER_STATUS_ENABLED:
helper->flags |= NF_CT_HELPER_F_CONFIGURED;
break;
case NFCT_HELPER_STATUS_DISABLED:
helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
break;
}
}
ret = nf_conntrack_helper_register(helper);
if (ret < 0)
goto err;
return 0;
err:
kfree(helper);
return ret;
}
static int
nfnl_cthelper_update(const struct nlattr * const tb[],
struct nf_conntrack_helper *helper)
{
int ret;
if (tb[NFCTH_PRIV_DATA_LEN])
return -EBUSY;
if (tb[NFCTH_POLICY]) {
ret = nfnl_cthelper_parse_expect_policy(helper,
tb[NFCTH_POLICY]);
if (ret < 0)
return ret;
}
if (tb[NFCTH_QUEUE_NUM])
helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
if (tb[NFCTH_STATUS]) {
int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
switch(status) {
case NFCT_HELPER_STATUS_ENABLED:
helper->flags |= NF_CT_HELPER_F_CONFIGURED;
break;
case NFCT_HELPER_STATUS_DISABLED:
helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
break;
}
}
return 0;
}
static int
nfnl_cthelper_new(struct sock *nfnl, struct sk_buff *skb,
const struct nlmsghdr *nlh, const struct nlattr * const tb[])
{
const char *helper_name;
struct nf_conntrack_helper *cur, *helper = NULL;
struct nf_conntrack_tuple tuple;
struct hlist_node *n;
int ret = 0, i;
if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
return -EINVAL;
helper_name = nla_data(tb[NFCTH_NAME]);
ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
if (ret < 0)
return ret;
rcu_read_lock();
for (i = 0; i < nf_ct_helper_hsize && !helper; i++) {
hlist_for_each_entry_rcu(cur, n, &nf_ct_helper_hash[i], hnode) {
/* skip non-userspace conntrack helpers. */
if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
continue;
if (strncmp(cur->name, helper_name,
NF_CT_HELPER_NAME_LEN) != 0)
continue;
if ((tuple.src.l3num != cur->tuple.src.l3num ||
tuple.dst.protonum != cur->tuple.dst.protonum))
continue;
if (nlh->nlmsg_flags & NLM_F_EXCL) {
ret = -EEXIST;
goto err;
}
helper = cur;
break;
}
}
rcu_read_unlock();
if (helper == NULL)
ret = nfnl_cthelper_create(tb, &tuple);
else
ret = nfnl_cthelper_update(tb, helper);
return ret;
err:
rcu_read_unlock();
return ret;
}
static int
nfnl_cthelper_dump_tuple(struct sk_buff *skb,
struct nf_conntrack_helper *helper)
{
struct nlattr *nest_parms;
nest_parms = nla_nest_start(skb, NFCTH_TUPLE | NLA_F_NESTED);
if (nest_parms == NULL)
goto nla_put_failure;
if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
htons(helper->tuple.src.l3num)))
goto nla_put_failure;
if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
goto nla_put_failure;
nla_nest_end(skb, nest_parms);
return 0;
nla_put_failure:
return -1;
}
static int
nfnl_cthelper_dump_policy(struct sk_buff *skb,
struct nf_conntrack_helper *helper)
{
int i;
struct nlattr *nest_parms1, *nest_parms2;
nest_parms1 = nla_nest_start(skb, NFCTH_POLICY | NLA_F_NESTED);
if (nest_parms1 == NULL)
goto nla_put_failure;
if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
htonl(helper->expect_class_max)))
goto nla_put_failure;
for (i=0; i<helper->expect_class_max; i++) {
nest_parms2 = nla_nest_start(skb,
(NFCTH_POLICY_SET+i) | NLA_F_NESTED);
if (nest_parms2 == NULL)
goto nla_put_failure;
if (nla_put_string(skb, NFCTH_POLICY_NAME,
helper->expect_policy[i].name))
goto nla_put_failure;
if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
htonl(helper->expect_policy[i].max_expected)))
goto nla_put_failure;
if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
htonl(helper->expect_policy[i].timeout)))
goto nla_put_failure;
nla_nest_end(skb, nest_parms2);
}
nla_nest_end(skb, nest_parms1);
return 0;
nla_put_failure:
return -1;
}
static int
nfnl_cthelper_fill_info(struct sk_buff *skb, u32 pid, u32 seq, u32 type,
int event, struct nf_conntrack_helper *helper)
{
struct nlmsghdr *nlh;
struct nfgenmsg *nfmsg;
unsigned int flags = pid ? NLM_F_MULTI : 0;
int status;
event |= NFNL_SUBSYS_CTHELPER << 8;
nlh = nlmsg_put(skb, pid, seq, event, sizeof(*nfmsg), flags);
if (nlh == NULL)
goto nlmsg_failure;
nfmsg = nlmsg_data(nlh);
nfmsg->nfgen_family = AF_UNSPEC;
nfmsg->version = NFNETLINK_V0;
nfmsg->res_id = 0;
if (nla_put_string(skb, NFCTH_NAME, helper->name))
goto nla_put_failure;
if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
goto nla_put_failure;
if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
goto nla_put_failure;
if (nfnl_cthelper_dump_policy(skb, helper) < 0)
goto nla_put_failure;
if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
goto nla_put_failure;
if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
status = NFCT_HELPER_STATUS_ENABLED;
else
status = NFCT_HELPER_STATUS_DISABLED;
if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
goto nla_put_failure;
nlmsg_end(skb, nlh);
return skb->len;
nlmsg_failure:
nla_put_failure:
nlmsg_cancel(skb, nlh);
return -1;
}
static int
nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
{
struct nf_conntrack_helper *cur, *last;
struct hlist_node *n;
rcu_read_lock();
last = (struct nf_conntrack_helper *)cb->args[1];
for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
restart:
hlist_for_each_entry_rcu(cur, n,
&nf_ct_helper_hash[cb->args[0]], hnode) {
/* skip non-userspace conntrack helpers. */
if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
continue;
if (cb->args[1]) {
if (cur != last)
continue;
cb->args[1] = 0;
}
if (nfnl_cthelper_fill_info(skb,
NETLINK_CB(cb->skb).pid,
cb->nlh->nlmsg_seq,
NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
NFNL_MSG_CTHELPER_NEW, cur) < 0) {
cb->args[1] = (unsigned long)cur;
goto out;
}
}
}
if (cb->args[1]) {
cb->args[1] = 0;
goto restart;
}
out:
rcu_read_unlock();
return skb->len;
}
static int
nfnl_cthelper_get(struct sock *nfnl, struct sk_buff *skb,
const struct nlmsghdr *nlh, const struct nlattr * const tb[])
{
int ret = -ENOENT, i;
struct nf_conntrack_helper *cur;
struct hlist_node *n;
struct sk_buff *skb2;
char *helper_name = NULL;
struct nf_conntrack_tuple tuple;
bool tuple_set = false;
if (nlh->nlmsg_flags & NLM_F_DUMP) {
struct netlink_dump_control c = {
.dump = nfnl_cthelper_dump_table,
};
return netlink_dump_start(nfnl, skb, nlh, &c);
}
if (tb[NFCTH_NAME])
helper_name = nla_data(tb[NFCTH_NAME]);
if (tb[NFCTH_TUPLE]) {
ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
if (ret < 0)
return ret;
tuple_set = true;
}
for (i = 0; i < nf_ct_helper_hsize; i++) {
hlist_for_each_entry_rcu(cur, n, &nf_ct_helper_hash[i], hnode) {
/* skip non-userspace conntrack helpers. */
if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
continue;
if (helper_name && strncmp(cur->name, helper_name,
NF_CT_HELPER_NAME_LEN) != 0) {
continue;
}
if (tuple_set &&
(tuple.src.l3num != cur->tuple.src.l3num ||
tuple.dst.protonum != cur->tuple.dst.protonum))
continue;
skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
if (skb2 == NULL) {
ret = -ENOMEM;
break;
}
ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).pid,
nlh->nlmsg_seq,
NFNL_MSG_TYPE(nlh->nlmsg_type),
NFNL_MSG_CTHELPER_NEW, cur);
if (ret <= 0) {
kfree_skb(skb2);
break;
}
ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).pid,
MSG_DONTWAIT);
if (ret > 0)
ret = 0;
/* this avoids a loop in nfnetlink. */
return ret == -EAGAIN ? -ENOBUFS : ret;
}
}
return ret;
}
static int
nfnl_cthelper_del(struct sock *nfnl, struct sk_buff *skb,
const struct nlmsghdr *nlh, const struct nlattr * const tb[])
{
char *helper_name = NULL;
struct nf_conntrack_helper *cur;
struct hlist_node *n, *tmp;
struct nf_conntrack_tuple tuple;
bool tuple_set = false, found = false;
int i, j = 0, ret;
if (tb[NFCTH_NAME])
helper_name = nla_data(tb[NFCTH_NAME]);
if (tb[NFCTH_TUPLE]) {
ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
if (ret < 0)
return ret;
tuple_set = true;
}
for (i = 0; i < nf_ct_helper_hsize; i++) {
hlist_for_each_entry_safe(cur, n, tmp, &nf_ct_helper_hash[i],
hnode) {
/* skip non-userspace conntrack helpers. */
if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
continue;
j++;
if (helper_name && strncmp(cur->name, helper_name,
NF_CT_HELPER_NAME_LEN) != 0) {
continue;
}
if (tuple_set &&
(tuple.src.l3num != cur->tuple.src.l3num ||
tuple.dst.protonum != cur->tuple.dst.protonum))
continue;
found = true;
nf_conntrack_helper_unregister(cur);
}
}
/* Make sure we return success if we flush and there is no helpers */
return (found || j == 0) ? 0 : -ENOENT;
}
static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
[NFCTH_NAME] = { .type = NLA_NUL_STRING,
.len = NF_CT_HELPER_NAME_LEN-1 },
[NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
};
static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
[NFNL_MSG_CTHELPER_NEW] = { .call = nfnl_cthelper_new,
.attr_count = NFCTH_MAX,
.policy = nfnl_cthelper_policy },
[NFNL_MSG_CTHELPER_GET] = { .call = nfnl_cthelper_get,
.attr_count = NFCTH_MAX,
.policy = nfnl_cthelper_policy },
[NFNL_MSG_CTHELPER_DEL] = { .call = nfnl_cthelper_del,
.attr_count = NFCTH_MAX,
.policy = nfnl_cthelper_policy },
};
static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
.name = "cthelper",
.subsys_id = NFNL_SUBSYS_CTHELPER,
.cb_count = NFNL_MSG_CTHELPER_MAX,
.cb = nfnl_cthelper_cb,
};
MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);
static int __init nfnl_cthelper_init(void)
{
int ret;
ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys);
if (ret < 0) {
pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
goto err_out;
}
return 0;
err_out:
return ret;
}
static void __exit nfnl_cthelper_exit(void)
{
struct nf_conntrack_helper *cur;
struct hlist_node *n, *tmp;
int i;
nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);
for (i=0; i<nf_ct_helper_hsize; i++) {
hlist_for_each_entry_safe(cur, n, tmp, &nf_ct_helper_hash[i],
hnode) {
/* skip non-userspace conntrack helpers. */
if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
continue;
nf_conntrack_helper_unregister(cur);
}
}
}
module_init(nfnl_cthelper_init);
module_exit(nfnl_cthelper_exit);