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Message-Id: <1339524380-2707-8-git-send-email-pablo@netfilter.org>
Date: Tue, 12 Jun 2012 20:06:20 +0200
From: pablo@...filter.org
To: netfilter-devel@...r.kernel.org
Cc: netdev@...r.kernel.org
Subject: [PATCH 7/7] netfilter: add user-space connection tracking helper infrastructure
From: Pablo Neira Ayuso <pablo@...filter.org>
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
[ 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@...filter.org>
---
include/linux/netfilter/Kbuild | 1 +
include/linux/netfilter/nfnetlink.h | 3 +-
include/linux/netfilter/nfnetlink_cthelper.h | 55 ++
include/linux/netfilter_ipv4.h | 1 +
include/linux/netfilter_ipv6.h | 1 +
include/net/netfilter/nf_conntrack_helper.h | 11 +
net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c | 49 +-
net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c | 49 +-
net/netfilter/Kconfig | 8 +
net/netfilter/Makefile | 1 +
net/netfilter/nf_conntrack_helper.c | 21 +-
net/netfilter/nfnetlink_cthelper.c | 674 ++++++++++++++++++++++++
12 files changed, 848 insertions(+), 26 deletions(-)
create mode 100644 include/linux/netfilter/nfnetlink_cthelper.h
create mode 100644 net/netfilter/nfnetlink_cthelper.c
diff --git a/include/linux/netfilter/Kbuild b/include/linux/netfilter/Kbuild
index 1697036..874ae8f 100644
--- a/include/linux/netfilter/Kbuild
+++ b/include/linux/netfilter/Kbuild
@@ -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
diff --git a/include/linux/netfilter/nfnetlink.h b/include/linux/netfilter/nfnetlink.h
index a1048c1..18341cd 100644
--- a/include/linux/netfilter/nfnetlink.h
+++ b/include/linux/netfilter/nfnetlink.h
@@ -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__
diff --git a/include/linux/netfilter/nfnetlink_cthelper.h b/include/linux/netfilter/nfnetlink_cthelper.h
new file mode 100644
index 0000000..33659f6
--- /dev/null
+++ b/include/linux/netfilter/nfnetlink_cthelper.h
@@ -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 */
diff --git a/include/linux/netfilter_ipv4.h b/include/linux/netfilter_ipv4.h
index fa0946c..e2b1280 100644
--- a/include/linux/netfilter_ipv4.h
+++ b/include/linux/netfilter_ipv4.h
@@ -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,
};
diff --git a/include/linux/netfilter_ipv6.h b/include/linux/netfilter_ipv6.h
index 57c0251..7c8a513 100644
--- a/include/linux/netfilter_ipv6.h
+++ b/include/linux/netfilter_ipv6.h
@@ -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,
};
diff --git a/include/net/netfilter/nf_conntrack_helper.h b/include/net/netfilter/nf_conntrack_helper.h
index 84b24c3..9aad956 100644
--- a/include/net/netfilter/nf_conntrack_helper.h
+++ b/include/net/netfilter/nf_conntrack_helper.h
@@ -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*/
diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
index d79b961..8227edc 100644
--- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
+++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
@@ -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)
+ return NF_ACCEPT;
/* adjust seqs for loopback traffic only in outgoing direction */
if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
@@ -140,7 +154,6 @@ static unsigned int ipv4_confirm(unsigned int hooknum,
return NF_DROP;
}
}
-out:
/* We've seen it coming out the other side: confirm it */
return nf_conntrack_confirm(skb);
}
@@ -185,6 +198,13 @@ static struct nf_hook_ops ipv4_conntrack_ops[] __read_mostly = {
.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,
.pf = NFPROTO_IPV4,
@@ -192,6 +212,13 @@ static struct nf_hook_ops ipv4_conntrack_ops[] __read_mostly = {
.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,
.pf = NFPROTO_IPV4,
diff --git a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
index fca10da..b656d06 100644
--- a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
+++ b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
@@ -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 +179,27 @@ 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 *))
+{
+ struct nf_conn *ct;
+ enum ip_conntrack_info ctinfo;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if (!ct || ctinfo == IP_CT_RELATED_REPLY)
+ return NF_ACCEPT;
+
/* We've seen it coming out the other side: confirm it */
return nf_conntrack_confirm(skb);
}
@@ -254,6 +269,13 @@ static struct nf_hook_ops ipv6_conntrack_ops[] __read_mostly = {
.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,
.pf = NFPROTO_IPV6,
@@ -261,6 +283,13 @@ static struct nf_hook_ops ipv6_conntrack_ops[] __read_mostly = {
.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,
.pf = NFPROTO_IPV6,
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 209c1ed..aae6c62 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -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
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 4e7960c..2f3bc0f 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -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
diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
index 9c18ecb..2918ec2 100644
--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -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);
diff --git a/net/netfilter/nfnetlink_cthelper.c b/net/netfilter/nfnetlink_cthelper.c
new file mode 100644
index 0000000..f399b46
--- /dev/null
+++ b/net/netfilter/nfnetlink_cthelper.c
@@ -0,0 +1,674 @@
+/*
+ * (C) 2012 Pablo Neira Ayuso <pablo@...filter.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@...filter.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;
+
+ pr_info("nfnl_cthelper: registering with nfnetlink.\n");
+ 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;
+
+ pr_info("nfnl_cthelper: unregistering from nfnetlink.\n");
+ 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);
--
1.7.10
--
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