[PATCH v4 nf-next] netfilter: allow disabling conntrack-on-by-default

[PATCH v4 nf-next] netfilter: allow disabling conntrack-on-by-default

[Florian Westphal]

Historically all the netfilter hooks got registered on module load time.

When net namespace support was added, hooks were registered in each
namespace (and new net namespaces inherit already-registered hooks from
global list).

This means that once nf_conntrack_ipv4/6.ko is loaded, all
existing and future net namespaces do connection tracking.

This series adds a new sysctl, nf_conntrack_default_on, that can be set
to 0 to disable this behaviour.

Once its set to 0, conntrack hooks are not registered in newly created
net namespaces, and new l3 protocol trackers are not registered with any
existing namespaces either.

The setting does NOT disable already-active connection tracking
in existing namespaces.

connection tracking is enabled via packet filter ruleset, regardless of
the sysctl setting, once a rule that needs conntrack functionality is
added (e.g. iptables -m conntrack, targets like SNAT/DNAT or nftables
equivalents make sure the hooks get registered, and deleted, as needed).

It is currently NOT possible to disable connection tracking inside a
net namespace that had its hooks registered implicitly due to
nf_conntrack_default_on=1 (except unloading the l3 tracker module).

Comments welcome.

 Documentation/networking/nf_conntrack-sysctl.txt |   11 +++
 include/net/netfilter/ipv4/nf_defrag_ipv4.h      |    3 
 include/net/netfilter/ipv6/nf_defrag_ipv6.h      |    3 
 include/net/netfilter/nf_conntrack.h             |    4 +
 include/net/netfilter/nf_conntrack_l3proto.h     |   16 ++++-
 include/net/netns/conntrack.h                    |    2 
 net/ipv4/netfilter/ipt_CLUSTERIP.c               |    4 -
 net/ipv4/netfilter/ipt_MASQUERADE.c              |    8 ++
 net/ipv4/netfilter/ipt_SYNPROXY.c                |    4 -
 net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c   |   62 ++++++++++++++-----
 net/ipv4/netfilter/nf_defrag_ipv4.c              |   41 +++++++++++-
 net/ipv4/netfilter/nft_masq_ipv4.c               |    7 ++
 net/ipv4/netfilter/nft_redir_ipv4.c              |    7 ++
 net/ipv6/netfilter/ip6t_SYNPROXY.c               |    4 -
 net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c   |   61 +++++++++++++++----
 net/ipv6/netfilter/nf_defrag_ipv6_hooks.c        |   42 +++++++++++--
 net/ipv6/netfilter/nft_masq_ipv6.c               |    7 ++
 net/ipv6/netfilter/nft_redir_ipv6.c              |    7 ++
 net/netfilter/nf_conntrack_proto.c               |   73 ++++++++++++++++++++---
 net/netfilter/nf_conntrack_standalone.c          |   10 +++
 net/netfilter/nft_ct.c                           |   26 ++++----
 net/netfilter/nft_masq.c                         |    2 
 net/netfilter/nft_nat.c                          |   11 +++
 net/netfilter/nft_redir.c                        |    2 
 net/netfilter/xt_CONNSECMARK.c                   |    4 -
 net/netfilter/xt_CT.c                            |    6 -
 net/netfilter/xt_NETMAP.c                        |   11 ++-
 net/netfilter/xt_REDIRECT.c                      |   12 +++
 net/netfilter/xt_TPROXY.c                        |   15 +++-
 net/netfilter/xt_connbytes.c                     |    4 -
 net/netfilter/xt_connlabel.c                     |    6 -
 net/netfilter/xt_connlimit.c                     |    6 -
 net/netfilter/xt_connmark.c                      |    8 +-
 net/netfilter/xt_conntrack.c                     |    4 -
 net/netfilter/xt_helper.c                        |    4 -
 net/netfilter/xt_nat.c                           |   18 +++++
 net/netfilter/xt_socket.c                        |   33 ++++++++--
 net/netfilter/xt_state.c                         |    4 -
 38 files changed, 443 insertions(+), 109 deletions(-)

[PATCH nf-next 1/7] conntrack: remove unused init_net hook

[Florian Westphal]

since adf0516845bcd0 ("netfilter: remove ip_conntrack* sysctl compat code")
the only user (ipv4 tracker) sets this to an empty stub function.

After this change nf_ct_l3proto_pernet_register() is also empty,
but this will change in a followup patch to add conditional register
of the hooks.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 include/net/netfilter/nf_conntrack_l3proto.h   | 3 ---
 net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c | 6 ------
 net/netfilter/nf_conntrack_proto.c             | 8 --------
 3 files changed, 17 deletions(-)

diff --git a/include/net/netfilter/nf_conntrack_l3proto.h b/include/net/netfilter/nf_conntrack_l3proto.h
index 8992e4229da9..cf8f3dfd810d 100644
--- a/include/net/netfilter/nf_conntrack_l3proto.h
+++ b/include/net/netfilter/nf_conntrack_l3proto.h
@@ -63,9 +63,6 @@ struct nf_conntrack_l3proto {
 
 	size_t nla_size;
 
-	/* Init l3proto pernet data */
-	int (*init_net)(struct net *net);
-
 	/* Module (if any) which this is connected to. */
 	struct module *me;
 };
diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
index 7130ed5dc1fa..823cf3331b9d 100644
--- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
+++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
@@ -307,11 +307,6 @@ static struct nf_sockopt_ops so_getorigdst = {
 	.owner		= THIS_MODULE,
 };
 
-static int ipv4_init_net(struct net *net)
-{
-	return 0;
-}
-
 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 __read_mostly = {
 	.l3proto	 = PF_INET,
 	.name		 = "ipv4",
@@ -325,7 +320,6 @@ struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 __read_mostly = {
 	.nlattr_to_tuple = ipv4_nlattr_to_tuple,
 	.nla_policy	 = ipv4_nla_policy,
 #endif
-	.init_net	 = ipv4_init_net,
 	.me		 = THIS_MODULE,
 };
 
diff --git a/net/netfilter/nf_conntrack_proto.c b/net/netfilter/nf_conntrack_proto.c
index 9bd34647225a..b218e70b2f74 100644
--- a/net/netfilter/nf_conntrack_proto.c
+++ b/net/netfilter/nf_conntrack_proto.c
@@ -193,14 +193,6 @@ EXPORT_SYMBOL_GPL(nf_ct_l3proto_register);
 int nf_ct_l3proto_pernet_register(struct net *net,
 				  struct nf_conntrack_l3proto *proto)
 {
-	int ret;
-
-	if (proto->init_net) {
-		ret = proto->init_net(net);
-		if (ret < 0)
-			return ret;
-	}
-
 	return 0;
 }
 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_register);
-- 
2.7.3

[PATCH v4 nf-next 2/7] netfilter: add and use nf_ct_netns_get/put

[Florian Westphal]

currently aliased to try_module_get/_put.
Will be changed in next patch when we add functions to make use of ->net
argument to store usercount per l3proto tracker.

This is needed to avoid registering the conntrack hooks in all netns and
later only enable connection tracking in those that need conntrack.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 No changes since v3.

 include/net/netfilter/nf_conntrack.h |  4 ++++
 net/ipv4/netfilter/ipt_CLUSTERIP.c   |  4 ++--
 net/ipv4/netfilter/ipt_SYNPROXY.c    |  4 ++--
 net/ipv6/netfilter/ip6t_SYNPROXY.c   |  4 ++--
 net/netfilter/nf_conntrack_proto.c   | 12 ++++++++++++
 net/netfilter/nft_ct.c               | 26 +++++++++++++-------------
 net/netfilter/xt_CONNSECMARK.c       |  4 ++--
 net/netfilter/xt_CT.c                |  6 +++---
 net/netfilter/xt_connbytes.c         |  4 ++--
 net/netfilter/xt_connlabel.c         |  6 +++---
 net/netfilter/xt_connlimit.c         |  6 +++---
 net/netfilter/xt_connmark.c          |  8 ++++----
 net/netfilter/xt_conntrack.c         |  4 ++--
 net/netfilter/xt_helper.c            |  4 ++--
 net/netfilter/xt_state.c             |  4 ++--
 15 files changed, 58 insertions(+), 42 deletions(-)

diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index 50418052a520..e1ab3b008510 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -181,6 +181,10 @@ static inline void nf_ct_put(struct nf_conn *ct)
 int nf_ct_l3proto_try_module_get(unsigned short l3proto);
 void nf_ct_l3proto_module_put(unsigned short l3proto);
 
+/* load module; enable/disable conntrack in this namespace */
+int nf_ct_netns_get(struct net *net, u8 nfproto);
+void nf_ct_netns_put(struct net *net, u8 nfproto);
+
 /*
  * Allocate a hashtable of hlist_head (if nulls == 0),
  * or hlist_nulls_head (if nulls == 1)
diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c
index 4a9e6db9df8d..2c3fe0697990 100644
--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
+++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
@@ -419,7 +419,7 @@ static int clusterip_tg_check(const struct xt_tgchk_param *par)
 	}
 	cipinfo->config = config;
 
-	ret = nf_ct_l3proto_try_module_get(par->family);
+	ret = nf_ct_netns_get(par->net, par->family);
 	if (ret < 0)
 		pr_info("cannot load conntrack support for proto=%u\n",
 			par->family);
@@ -444,7 +444,7 @@ static void clusterip_tg_destroy(const struct xt_tgdtor_param *par)
 
 	clusterip_config_put(cipinfo->config);
 
-	nf_ct_l3proto_module_put(par->family);
+	nf_ct_netns_get(par->net, par->family);
 }
 
 #ifdef CONFIG_COMPAT
diff --git a/net/ipv4/netfilter/ipt_SYNPROXY.c b/net/ipv4/netfilter/ipt_SYNPROXY.c
index 361411688221..30c0de53e254 100644
--- a/net/ipv4/netfilter/ipt_SYNPROXY.c
+++ b/net/ipv4/netfilter/ipt_SYNPROXY.c
@@ -418,12 +418,12 @@ static int synproxy_tg4_check(const struct xt_tgchk_param *par)
 	    e->ip.invflags & XT_INV_PROTO)
 		return -EINVAL;
 
-	return nf_ct_l3proto_try_module_get(par->family);
+	return nf_ct_netns_get(par->net, par->family);
 }
 
 static void synproxy_tg4_destroy(const struct xt_tgdtor_param *par)
 {
-	nf_ct_l3proto_module_put(par->family);
+	nf_ct_netns_put(par->net, par->family);
 }
 
 static struct xt_target synproxy_tg4_reg __read_mostly = {
diff --git a/net/ipv6/netfilter/ip6t_SYNPROXY.c b/net/ipv6/netfilter/ip6t_SYNPROXY.c
index 99a1216287c8..98c8dd38575a 100644
--- a/net/ipv6/netfilter/ip6t_SYNPROXY.c
+++ b/net/ipv6/netfilter/ip6t_SYNPROXY.c
@@ -440,12 +440,12 @@ static int synproxy_tg6_check(const struct xt_tgchk_param *par)
 	    e->ipv6.invflags & XT_INV_PROTO)
 		return -EINVAL;
 
-	return nf_ct_l3proto_try_module_get(par->family);
+	return nf_ct_netns_get(par->net, par->family);
 }
 
 static void synproxy_tg6_destroy(const struct xt_tgdtor_param *par)
 {
-	nf_ct_l3proto_module_put(par->family);
+	nf_ct_netns_put(par->net, par->family);
 }
 
 static struct xt_target synproxy_tg6_reg __read_mostly = {
diff --git a/net/netfilter/nf_conntrack_proto.c b/net/netfilter/nf_conntrack_proto.c
index b218e70b2f74..948f1e2fc80b 100644
--- a/net/netfilter/nf_conntrack_proto.c
+++ b/net/netfilter/nf_conntrack_proto.c
@@ -125,6 +125,18 @@ void nf_ct_l3proto_module_put(unsigned short l3proto)
 }
 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
 
+int nf_ct_netns_get(struct net *net, u8 nfproto)
+{
+	return nf_ct_l3proto_try_module_get(nfproto);
+}
+EXPORT_SYMBOL_GPL(nf_ct_netns_get);
+
+void nf_ct_netns_put(struct net *net, u8 nfproto)
+{
+	nf_ct_l3proto_module_put(nfproto);
+}
+EXPORT_SYMBOL_GPL(nf_ct_netns_put);
+
 struct nf_conntrack_l4proto *
 nf_ct_l4proto_find_get(u_int16_t l3num, u_int8_t l4num)
 {
diff --git a/net/netfilter/nft_ct.c b/net/netfilter/nft_ct.c
index 6837348c8993..e6baeaebe653 100644
--- a/net/netfilter/nft_ct.c
+++ b/net/netfilter/nft_ct.c
@@ -208,37 +208,37 @@ static const struct nla_policy nft_ct_policy[NFTA_CT_MAX + 1] = {
 	[NFTA_CT_SREG]		= { .type = NLA_U32 },
 };
 
-static int nft_ct_l3proto_try_module_get(uint8_t family)
+static int nft_ct_netns_get(struct net *net, uint8_t family)
 {
 	int err;
 
 	if (family == NFPROTO_INET) {
-		err = nf_ct_l3proto_try_module_get(NFPROTO_IPV4);
+		err = nf_ct_netns_get(net, NFPROTO_IPV4);
 		if (err < 0)
 			goto err1;
-		err = nf_ct_l3proto_try_module_get(NFPROTO_IPV6);
+		err = nf_ct_netns_get(net, NFPROTO_IPV6);
 		if (err < 0)
 			goto err2;
 	} else {
-		err = nf_ct_l3proto_try_module_get(family);
+		err = nf_ct_netns_get(net, family);
 		if (err < 0)
 			goto err1;
 	}
 	return 0;
 
 err2:
-	nf_ct_l3proto_module_put(NFPROTO_IPV4);
+	nf_ct_netns_put(net, NFPROTO_IPV4);
 err1:
 	return err;
 }
 
-static void nft_ct_l3proto_module_put(uint8_t family)
+static void nft_ct_netns_put(struct net *net, uint8_t family)
 {
 	if (family == NFPROTO_INET) {
-		nf_ct_l3proto_module_put(NFPROTO_IPV4);
-		nf_ct_l3proto_module_put(NFPROTO_IPV6);
+		nf_ct_netns_put(net, NFPROTO_IPV4);
+		nf_ct_netns_put(net, NFPROTO_IPV6);
 	} else
-		nf_ct_l3proto_module_put(family);
+		nf_ct_netns_put(net, family);
 }
 
 static int nft_ct_get_init(const struct nft_ctx *ctx,
@@ -342,7 +342,7 @@ static int nft_ct_get_init(const struct nft_ctx *ctx,
 	if (err < 0)
 		return err;
 
-	err = nft_ct_l3proto_try_module_get(ctx->afi->family);
+	err = nft_ct_netns_get(ctx->net, ctx->afi->family);
 	if (err < 0)
 		return err;
 
@@ -390,7 +390,7 @@ static int nft_ct_set_init(const struct nft_ctx *ctx,
 	if (err < 0)
 		goto err1;
 
-	err = nft_ct_l3proto_try_module_get(ctx->afi->family);
+	err = nft_ct_netns_get(ctx->net, ctx->afi->family);
 	if (err < 0)
 		goto err1;
 
@@ -405,7 +405,7 @@ static int nft_ct_set_init(const struct nft_ctx *ctx,
 static void nft_ct_get_destroy(const struct nft_ctx *ctx,
 			       const struct nft_expr *expr)
 {
-	nft_ct_l3proto_module_put(ctx->afi->family);
+	nf_ct_netns_put(ctx->net, ctx->afi->family);
 }
 
 static void nft_ct_set_destroy(const struct nft_ctx *ctx,
@@ -423,7 +423,7 @@ static void nft_ct_set_destroy(const struct nft_ctx *ctx,
 		break;
 	}
 
-	nft_ct_l3proto_module_put(ctx->afi->family);
+	nft_ct_netns_put(ctx->net, ctx->afi->family);
 }
 
 static int nft_ct_get_dump(struct sk_buff *skb, const struct nft_expr *expr)
diff --git a/net/netfilter/xt_CONNSECMARK.c b/net/netfilter/xt_CONNSECMARK.c
index e04dc282e3bb..da56c06a443c 100644
--- a/net/netfilter/xt_CONNSECMARK.c
+++ b/net/netfilter/xt_CONNSECMARK.c
@@ -106,7 +106,7 @@ static int connsecmark_tg_check(const struct xt_tgchk_param *par)
 		return -EINVAL;
 	}
 
-	ret = nf_ct_l3proto_try_module_get(par->family);
+	ret = nf_ct_netns_get(par->net, par->family);
 	if (ret < 0)
 		pr_info("cannot load conntrack support for proto=%u\n",
 			par->family);
@@ -115,7 +115,7 @@ static int connsecmark_tg_check(const struct xt_tgchk_param *par)
 
 static void connsecmark_tg_destroy(const struct xt_tgdtor_param *par)
 {
-	nf_ct_l3proto_module_put(par->family);
+	nf_ct_netns_put(par->net, par->family);
 }
 
 static struct xt_target connsecmark_tg_reg __read_mostly = {
diff --git a/net/netfilter/xt_CT.c b/net/netfilter/xt_CT.c
index 6669e68d589e..95c750358747 100644
--- a/net/netfilter/xt_CT.c
+++ b/net/netfilter/xt_CT.c
@@ -216,7 +216,7 @@ static int xt_ct_tg_check(const struct xt_tgchk_param *par,
 		goto err1;
 #endif
 
-	ret = nf_ct_l3proto_try_module_get(par->family);
+	ret = nf_ct_netns_get(par->net, par->family);
 	if (ret < 0)
 		goto err1;
 
@@ -260,7 +260,7 @@ static int xt_ct_tg_check(const struct xt_tgchk_param *par,
 err3:
 	nf_ct_tmpl_free(ct);
 err2:
-	nf_ct_l3proto_module_put(par->family);
+	nf_ct_netns_put(par->net, par->family);
 err1:
 	return ret;
 }
@@ -341,7 +341,7 @@ static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par,
 		if (help)
 			module_put(help->helper->me);
 
-		nf_ct_l3proto_module_put(par->family);
+		nf_ct_netns_put(par->net, par->family);
 
 		xt_ct_destroy_timeout(ct);
 		nf_ct_put(info->ct);
diff --git a/net/netfilter/xt_connbytes.c b/net/netfilter/xt_connbytes.c
index d4bec261e74e..cad0b7b5eb35 100644
--- a/net/netfilter/xt_connbytes.c
+++ b/net/netfilter/xt_connbytes.c
@@ -110,7 +110,7 @@ static int connbytes_mt_check(const struct xt_mtchk_param *par)
 	    sinfo->direction != XT_CONNBYTES_DIR_BOTH)
 		return -EINVAL;
 
-	ret = nf_ct_l3proto_try_module_get(par->family);
+	ret = nf_ct_netns_get(par->net, par->family);
 	if (ret < 0)
 		pr_info("cannot load conntrack support for proto=%u\n",
 			par->family);
@@ -129,7 +129,7 @@ static int connbytes_mt_check(const struct xt_mtchk_param *par)
 
 static void connbytes_mt_destroy(const struct xt_mtdtor_param *par)
 {
-	nf_ct_l3proto_module_put(par->family);
+	nf_ct_netns_put(par->net, par->family);
 }
 
 static struct xt_match connbytes_mt_reg __read_mostly = {
diff --git a/net/netfilter/xt_connlabel.c b/net/netfilter/xt_connlabel.c
index 03d66f1c5e69..7827128d5a95 100644
--- a/net/netfilter/xt_connlabel.c
+++ b/net/netfilter/xt_connlabel.c
@@ -61,7 +61,7 @@ static int connlabel_mt_check(const struct xt_mtchk_param *par)
 		return -EINVAL;
 	}
 
-	ret = nf_ct_l3proto_try_module_get(par->family);
+	ret = nf_ct_netns_get(par->net, par->family);
 	if (ret < 0) {
 		pr_info("cannot load conntrack support for proto=%u\n",
 							par->family);
@@ -70,14 +70,14 @@ static int connlabel_mt_check(const struct xt_mtchk_param *par)
 
 	ret = nf_connlabels_get(par->net, info->bit);
 	if (ret < 0)
-		nf_ct_l3proto_module_put(par->family);
+		nf_ct_netns_put(par->net, par->family);
 	return ret;
 }
 
 static void connlabel_mt_destroy(const struct xt_mtdtor_param *par)
 {
 	nf_connlabels_put(par->net);
-	nf_ct_l3proto_module_put(par->family);
+	nf_ct_netns_put(par->net, par->family);
 }
 
 static struct xt_match connlabels_mt_reg __read_mostly = {
diff --git a/net/netfilter/xt_connlimit.c b/net/netfilter/xt_connlimit.c
index bb3845339efd..2aff2b7c4689 100644
--- a/net/netfilter/xt_connlimit.c
+++ b/net/netfilter/xt_connlimit.c
@@ -368,7 +368,7 @@ static int connlimit_mt_check(const struct xt_mtchk_param *par)
 
 	net_get_random_once(&connlimit_rnd, sizeof(connlimit_rnd));
 
-	ret = nf_ct_l3proto_try_module_get(par->family);
+	ret = nf_ct_netns_get(par->net, par->family);
 	if (ret < 0) {
 		pr_info("cannot load conntrack support for "
 			"address family %u\n", par->family);
@@ -378,7 +378,7 @@ static int connlimit_mt_check(const struct xt_mtchk_param *par)
 	/* init private data */
 	info->data = kmalloc(sizeof(struct xt_connlimit_data), GFP_KERNEL);
 	if (info->data == NULL) {
-		nf_ct_l3proto_module_put(par->family);
+		nf_ct_netns_put(par->net, par->family);
 		return -ENOMEM;
 	}
 
@@ -414,7 +414,7 @@ static void connlimit_mt_destroy(const struct xt_mtdtor_param *par)
 	const struct xt_connlimit_info *info = par->matchinfo;
 	unsigned int i;
 
-	nf_ct_l3proto_module_put(par->family);
+	nf_ct_netns_put(par->net, par->family);
 
 	for (i = 0; i < ARRAY_SIZE(info->data->climit_root4); ++i)
 		destroy_tree(&info->data->climit_root4[i]);
diff --git a/net/netfilter/xt_connmark.c b/net/netfilter/xt_connmark.c
index 69f78e96fdb4..ec377cc6a369 100644
--- a/net/netfilter/xt_connmark.c
+++ b/net/netfilter/xt_connmark.c
@@ -77,7 +77,7 @@ static int connmark_tg_check(const struct xt_tgchk_param *par)
 {
 	int ret;
 
-	ret = nf_ct_l3proto_try_module_get(par->family);
+	ret = nf_ct_netns_get(par->net, par->family);
 	if (ret < 0)
 		pr_info("cannot load conntrack support for proto=%u\n",
 			par->family);
@@ -86,7 +86,7 @@ static int connmark_tg_check(const struct xt_tgchk_param *par)
 
 static void connmark_tg_destroy(const struct xt_tgdtor_param *par)
 {
-	nf_ct_l3proto_module_put(par->family);
+	nf_ct_netns_put(par->net, par->family);
 }
 
 static bool
@@ -107,7 +107,7 @@ static int connmark_mt_check(const struct xt_mtchk_param *par)
 {
 	int ret;
 
-	ret = nf_ct_l3proto_try_module_get(par->family);
+	ret = nf_ct_netns_get(par->net, par->family);
 	if (ret < 0)
 		pr_info("cannot load conntrack support for proto=%u\n",
 			par->family);
@@ -116,7 +116,7 @@ static int connmark_mt_check(const struct xt_mtchk_param *par)
 
 static void connmark_mt_destroy(const struct xt_mtdtor_param *par)
 {
-	nf_ct_l3proto_module_put(par->family);
+	nf_ct_netns_put(par->net, par->family);
 }
 
 static struct xt_target connmark_tg_reg __read_mostly = {
diff --git a/net/netfilter/xt_conntrack.c b/net/netfilter/xt_conntrack.c
index 2dea15ebc55b..c0fb217bc649 100644
--- a/net/netfilter/xt_conntrack.c
+++ b/net/netfilter/xt_conntrack.c
@@ -271,7 +271,7 @@ static int conntrack_mt_check(const struct xt_mtchk_param *par)
 {
 	int ret;
 
-	ret = nf_ct_l3proto_try_module_get(par->family);
+	ret = nf_ct_netns_get(par->net, par->family);
 	if (ret < 0)
 		pr_info("cannot load conntrack support for proto=%u\n",
 			par->family);
@@ -280,7 +280,7 @@ static int conntrack_mt_check(const struct xt_mtchk_param *par)
 
 static void conntrack_mt_destroy(const struct xt_mtdtor_param *par)
 {
-	nf_ct_l3proto_module_put(par->family);
+	nf_ct_netns_put(par->net, par->family);
 }
 
 static struct xt_match conntrack_mt_reg[] __read_mostly = {
diff --git a/net/netfilter/xt_helper.c b/net/netfilter/xt_helper.c
index f679dd4c272a..38a78151c0e9 100644
--- a/net/netfilter/xt_helper.c
+++ b/net/netfilter/xt_helper.c
@@ -59,7 +59,7 @@ static int helper_mt_check(const struct xt_mtchk_param *par)
 	struct xt_helper_info *info = par->matchinfo;
 	int ret;
 
-	ret = nf_ct_l3proto_try_module_get(par->family);
+	ret = nf_ct_netns_get(par->net, par->family);
 	if (ret < 0) {
 		pr_info("cannot load conntrack support for proto=%u\n",
 			par->family);
@@ -71,7 +71,7 @@ static int helper_mt_check(const struct xt_mtchk_param *par)
 
 static void helper_mt_destroy(const struct xt_mtdtor_param *par)
 {
-	nf_ct_l3proto_module_put(par->family);
+	nf_ct_netns_put(par->net, par->family);
 }
 
 static struct xt_match helper_mt_reg __read_mostly = {
diff --git a/net/netfilter/xt_state.c b/net/netfilter/xt_state.c
index a507922d80cd..5746a33789a5 100644
--- a/net/netfilter/xt_state.c
+++ b/net/netfilter/xt_state.c
@@ -43,7 +43,7 @@ static int state_mt_check(const struct xt_mtchk_param *par)
 {
 	int ret;
 
-	ret = nf_ct_l3proto_try_module_get(par->family);
+	ret = nf_ct_netns_get(par->net, par->family);
 	if (ret < 0)
 		pr_info("cannot load conntrack support for proto=%u\n",
 			par->family);
@@ -52,7 +52,7 @@ static int state_mt_check(const struct xt_mtchk_param *par)
 
 static void state_mt_destroy(const struct xt_mtdtor_param *par)
 {
-	nf_ct_l3proto_module_put(par->family);
+	nf_ct_netns_put(par->net, par->family);
 }
 
 static struct xt_match state_mt_reg __read_mostly = {
-- 
2.7.3

[PATCH v4 nf-next 3/7] netfilter: nat: add dependencies on conntrack module

[Florian Westphal]

MASQUERADE, S/DNAT and REDIRECT already call functions that depend on the
conntrack module.

However, since the conntrack hooks are now registered in a lazy fashion
(i.e., only when needed) a symbol reference is not enough.

Thus, when something is added to a nat table, make sure that it will see
packets by calling nf_ct_netns_get() which will register the conntrack
hooks in the current netns.

An alternative would be to add these dependencies to the NAT table.

However, that has problems when using non-modular builds -- we might
register e.g. ipv6 conntrack before its initcall has run, leading to NULL
deref crashes since its per-netns storage has not yet been allocated.

Adding the dependency in the modules instead has the advantage that nat
table also does not register its hooks until rules are added.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 No changes since v3.

 net/ipv4/netfilter/ipt_MASQUERADE.c |  8 +++++++-
 net/netfilter/xt_NETMAP.c           | 11 +++++++++--
 net/netfilter/xt_REDIRECT.c         | 12 ++++++++++--
 net/netfilter/xt_nat.c              | 18 +++++++++++++++++-
 4 files changed, 43 insertions(+), 6 deletions(-)

diff --git a/net/ipv4/netfilter/ipt_MASQUERADE.c b/net/ipv4/netfilter/ipt_MASQUERADE.c
index 34cfb9b0bc0a..a03e4e7ef5f9 100644
--- a/net/ipv4/netfilter/ipt_MASQUERADE.c
+++ b/net/ipv4/netfilter/ipt_MASQUERADE.c
@@ -41,7 +41,7 @@ static int masquerade_tg_check(const struct xt_tgchk_param *par)
 		pr_debug("bad rangesize %u\n", mr->rangesize);
 		return -EINVAL;
 	}
-	return 0;
+	return nf_ct_netns_get(par->net, par->family);
 }
 
 static unsigned int
@@ -59,6 +59,11 @@ masquerade_tg(struct sk_buff *skb, const struct xt_action_param *par)
 				      xt_out(par));
 }
 
+static void masquerade_tg_destroy(const struct xt_tgdtor_param *par)
+{
+	nf_ct_netns_put(par->net, par->family);
+}
+
 static struct xt_target masquerade_tg_reg __read_mostly = {
 	.name		= "MASQUERADE",
 	.family		= NFPROTO_IPV4,
@@ -67,6 +72,7 @@ static struct xt_target masquerade_tg_reg __read_mostly = {
 	.table		= "nat",
 	.hooks		= 1 << NF_INET_POST_ROUTING,
 	.checkentry	= masquerade_tg_check,
+	.destroy	= masquerade_tg_destroy,
 	.me		= THIS_MODULE,
 };
 
diff --git a/net/netfilter/xt_NETMAP.c b/net/netfilter/xt_NETMAP.c
index 94d0b5411192..e45a01255e70 100644
--- a/net/netfilter/xt_NETMAP.c
+++ b/net/netfilter/xt_NETMAP.c
@@ -60,7 +60,12 @@ static int netmap_tg6_checkentry(const struct xt_tgchk_param *par)
 
 	if (!(range->flags & NF_NAT_RANGE_MAP_IPS))
 		return -EINVAL;
-	return 0;
+	return nf_ct_netns_get(par->net, par->family);
+}
+
+static void netmap_tg_destroy(const struct xt_tgdtor_param *par)
+{
+	nf_ct_netns_put(par->net, par->family);
 }
 
 static unsigned int
@@ -111,7 +116,7 @@ static int netmap_tg4_check(const struct xt_tgchk_param *par)
 		pr_debug("bad rangesize %u.\n", mr->rangesize);
 		return -EINVAL;
 	}
-	return 0;
+	return nf_ct_netns_get(par->net, par->family);
 }
 
 static struct xt_target netmap_tg_reg[] __read_mostly = {
@@ -127,6 +132,7 @@ static struct xt_target netmap_tg_reg[] __read_mostly = {
 		              (1 << NF_INET_LOCAL_OUT) |
 		              (1 << NF_INET_LOCAL_IN),
 		.checkentry = netmap_tg6_checkentry,
+		.destroy    = netmap_tg_destroy,
 		.me         = THIS_MODULE,
 	},
 	{
@@ -141,6 +147,7 @@ static struct xt_target netmap_tg_reg[] __read_mostly = {
 		              (1 << NF_INET_LOCAL_OUT) |
 		              (1 << NF_INET_LOCAL_IN),
 		.checkentry = netmap_tg4_check,
+		.destroy    = netmap_tg_destroy,
 		.me         = THIS_MODULE,
 	},
 };
diff --git a/net/netfilter/xt_REDIRECT.c b/net/netfilter/xt_REDIRECT.c
index 651dce65a30b..98a4c6d4f1cb 100644
--- a/net/netfilter/xt_REDIRECT.c
+++ b/net/netfilter/xt_REDIRECT.c
@@ -40,7 +40,13 @@ static int redirect_tg6_checkentry(const struct xt_tgchk_param *par)
 
 	if (range->flags & NF_NAT_RANGE_MAP_IPS)
 		return -EINVAL;
-	return 0;
+
+	return nf_ct_netns_get(par->net, par->family);
+}
+
+static void redirect_tg_destroy(const struct xt_tgdtor_param *par)
+{
+	nf_ct_netns_put(par->net, par->family);
 }
 
 /* FIXME: Take multiple ranges --RR */
@@ -56,7 +62,7 @@ static int redirect_tg4_check(const struct xt_tgchk_param *par)
 		pr_debug("bad rangesize %u.\n", mr->rangesize);
 		return -EINVAL;
 	}
-	return 0;
+	return nf_ct_netns_get(par->net, par->family);
 }
 
 static unsigned int
@@ -72,6 +78,7 @@ static struct xt_target redirect_tg_reg[] __read_mostly = {
 		.revision   = 0,
 		.table      = "nat",
 		.checkentry = redirect_tg6_checkentry,
+		.destroy    = redirect_tg_destroy,
 		.target     = redirect_tg6,
 		.targetsize = sizeof(struct nf_nat_range),
 		.hooks      = (1 << NF_INET_PRE_ROUTING) |
@@ -85,6 +92,7 @@ static struct xt_target redirect_tg_reg[] __read_mostly = {
 		.table      = "nat",
 		.target     = redirect_tg4,
 		.checkentry = redirect_tg4_check,
+		.destroy    = redirect_tg_destroy,
 		.targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
 		.hooks      = (1 << NF_INET_PRE_ROUTING) |
 		              (1 << NF_INET_LOCAL_OUT),
diff --git a/net/netfilter/xt_nat.c b/net/netfilter/xt_nat.c
index bea7464cc43f..8107b3eb865f 100644
--- a/net/netfilter/xt_nat.c
+++ b/net/netfilter/xt_nat.c
@@ -23,7 +23,17 @@ static int xt_nat_checkentry_v0(const struct xt_tgchk_param *par)
 			par->target->name);
 		return -EINVAL;
 	}
-	return 0;
+	return nf_ct_netns_get(par->net, par->family);
+}
+
+static int xt_nat_checkentry(const struct xt_tgchk_param *par)
+{
+	return nf_ct_netns_get(par->net, par->family);
+}
+
+static void xt_nat_destroy(const struct xt_tgdtor_param *par)
+{
+	nf_ct_netns_put(par->net, par->family);
 }
 
 static void xt_nat_convert_range(struct nf_nat_range *dst,
@@ -106,6 +116,7 @@ static struct xt_target xt_nat_target_reg[] __read_mostly = {
 		.name		= "SNAT",
 		.revision	= 0,
 		.checkentry	= xt_nat_checkentry_v0,
+		.destroy	= xt_nat_destroy,
 		.target		= xt_snat_target_v0,
 		.targetsize	= sizeof(struct nf_nat_ipv4_multi_range_compat),
 		.family		= NFPROTO_IPV4,
@@ -118,6 +129,7 @@ static struct xt_target xt_nat_target_reg[] __read_mostly = {
 		.name		= "DNAT",
 		.revision	= 0,
 		.checkentry	= xt_nat_checkentry_v0,
+		.destroy	= xt_nat_destroy,
 		.target		= xt_dnat_target_v0,
 		.targetsize	= sizeof(struct nf_nat_ipv4_multi_range_compat),
 		.family		= NFPROTO_IPV4,
@@ -129,6 +141,8 @@ static struct xt_target xt_nat_target_reg[] __read_mostly = {
 	{
 		.name		= "SNAT",
 		.revision	= 1,
+		.checkentry	= xt_nat_checkentry,
+		.destroy	= xt_nat_destroy,
 		.target		= xt_snat_target_v1,
 		.targetsize	= sizeof(struct nf_nat_range),
 		.table		= "nat",
@@ -139,6 +153,8 @@ static struct xt_target xt_nat_target_reg[] __read_mostly = {
 	{
 		.name		= "DNAT",
 		.revision	= 1,
+		.checkentry	= xt_nat_checkentry,
+		.destroy	= xt_nat_destroy,
 		.target		= xt_dnat_target_v1,
 		.targetsize	= sizeof(struct nf_nat_range),
 		.table		= "nat",
-- 
2.7.3

[PATCH v4 nf-next 4/7] nftables: add conntrack dependencies for nat/masq/redir expressions

[Florian Westphal]

so that conntrack core will add the needed hooks in this namespace.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 no changes since v3.

 net/ipv4/netfilter/nft_masq_ipv4.c  |  7 +++++++
 net/ipv4/netfilter/nft_redir_ipv4.c |  7 +++++++
 net/ipv6/netfilter/nft_masq_ipv6.c  |  7 +++++++
 net/ipv6/netfilter/nft_redir_ipv6.c |  7 +++++++
 net/netfilter/nft_masq.c            |  2 +-
 net/netfilter/nft_nat.c             | 11 ++++++++++-
 net/netfilter/nft_redir.c           |  2 +-
 7 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/netfilter/nft_masq_ipv4.c b/net/ipv4/netfilter/nft_masq_ipv4.c
index 4f697e431811..914da9188820 100644
--- a/net/ipv4/netfilter/nft_masq_ipv4.c
+++ b/net/ipv4/netfilter/nft_masq_ipv4.c
@@ -35,12 +35,19 @@ static void nft_masq_ipv4_eval(const struct nft_expr *expr,
 						    &range, nft_out(pkt));
 }
 
+static void
+nft_masq_ipv4_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
+{
+	nf_ct_netns_put(ctx->net, NFPROTO_IPV4);
+}
+
 static struct nft_expr_type nft_masq_ipv4_type;
 static const struct nft_expr_ops nft_masq_ipv4_ops = {
 	.type		= &nft_masq_ipv4_type,
 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_masq)),
 	.eval		= nft_masq_ipv4_eval,
 	.init		= nft_masq_init,
+	.destroy	= nft_masq_ipv4_destroy,
 	.dump		= nft_masq_dump,
 	.validate	= nft_masq_validate,
 };
diff --git a/net/ipv4/netfilter/nft_redir_ipv4.c b/net/ipv4/netfilter/nft_redir_ipv4.c
index 16df0493c5ce..94238fe3bccc 100644
--- a/net/ipv4/netfilter/nft_redir_ipv4.c
+++ b/net/ipv4/netfilter/nft_redir_ipv4.c
@@ -38,12 +38,19 @@ static void nft_redir_ipv4_eval(const struct nft_expr *expr,
 	regs->verdict.code = nf_nat_redirect_ipv4(pkt->skb, &mr, nft_hook(pkt));
 }
 
+static void
+nft_redir_ipv4_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
+{
+	nf_ct_netns_put(ctx->net, NFPROTO_IPV4);
+}
+
 static struct nft_expr_type nft_redir_ipv4_type;
 static const struct nft_expr_ops nft_redir_ipv4_ops = {
 	.type		= &nft_redir_ipv4_type,
 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_redir)),
 	.eval		= nft_redir_ipv4_eval,
 	.init		= nft_redir_init,
+	.destroy	= nft_redir_ipv4_destroy,
 	.dump		= nft_redir_dump,
 	.validate	= nft_redir_validate,
 };
diff --git a/net/ipv6/netfilter/nft_masq_ipv6.c b/net/ipv6/netfilter/nft_masq_ipv6.c
index a2aff1277b40..c79dcb87f4a3 100644
--- a/net/ipv6/netfilter/nft_masq_ipv6.c
+++ b/net/ipv6/netfilter/nft_masq_ipv6.c
@@ -36,12 +36,19 @@ static void nft_masq_ipv6_eval(const struct nft_expr *expr,
 						    nft_out(pkt));
 }
 
+static void
+nft_masq_ipv6_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
+{
+	nf_ct_netns_put(ctx->net, NFPROTO_IPV6);
+}
+
 static struct nft_expr_type nft_masq_ipv6_type;
 static const struct nft_expr_ops nft_masq_ipv6_ops = {
 	.type		= &nft_masq_ipv6_type,
 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_masq)),
 	.eval		= nft_masq_ipv6_eval,
 	.init		= nft_masq_init,
+	.destroy	= nft_masq_ipv6_destroy,
 	.dump		= nft_masq_dump,
 	.validate	= nft_masq_validate,
 };
diff --git a/net/ipv6/netfilter/nft_redir_ipv6.c b/net/ipv6/netfilter/nft_redir_ipv6.c
index bfcd5af6bc15..88dd1d94ed25 100644
--- a/net/ipv6/netfilter/nft_redir_ipv6.c
+++ b/net/ipv6/netfilter/nft_redir_ipv6.c
@@ -39,12 +39,19 @@ static void nft_redir_ipv6_eval(const struct nft_expr *expr,
 		nf_nat_redirect_ipv6(pkt->skb, &range, nft_hook(pkt));
 }
 
+static void
+nft_redir_ipv6_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
+{
+	nf_ct_netns_put(ctx->net, NFPROTO_IPV6);
+}
+
 static struct nft_expr_type nft_redir_ipv6_type;
 static const struct nft_expr_ops nft_redir_ipv6_ops = {
 	.type		= &nft_redir_ipv6_type,
 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_redir)),
 	.eval		= nft_redir_ipv6_eval,
 	.init		= nft_redir_init,
+	.destroy	= nft_redir_ipv6_destroy,
 	.dump		= nft_redir_dump,
 	.validate	= nft_redir_validate,
 };
diff --git a/net/netfilter/nft_masq.c b/net/netfilter/nft_masq.c
index 81b5ad6165ac..f90e49c990f9 100644
--- a/net/netfilter/nft_masq.c
+++ b/net/netfilter/nft_masq.c
@@ -77,7 +77,7 @@ int nft_masq_init(const struct nft_ctx *ctx,
 		}
 	}
 
-	return 0;
+	return nf_ct_netns_get(ctx->net, ctx->afi->family);
 }
 EXPORT_SYMBOL_GPL(nft_masq_init);
 
diff --git a/net/netfilter/nft_nat.c b/net/netfilter/nft_nat.c
index ee2d71753746..19a7bf3236f9 100644
--- a/net/netfilter/nft_nat.c
+++ b/net/netfilter/nft_nat.c
@@ -209,7 +209,7 @@ static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 			return -EINVAL;
 	}
 
-	return 0;
+	return nf_ct_netns_get(ctx->net, family);
 }
 
 static int nft_nat_dump(struct sk_buff *skb, const struct nft_expr *expr)
@@ -257,12 +257,21 @@ static int nft_nat_dump(struct sk_buff *skb, const struct nft_expr *expr)
 	return -1;
 }
 
+static void
+nft_nat_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
+{
+	const struct nft_nat *priv = nft_expr_priv(expr);
+
+	nf_ct_netns_put(ctx->net, priv->family);
+}
+
 static struct nft_expr_type nft_nat_type;
 static const struct nft_expr_ops nft_nat_ops = {
 	.type           = &nft_nat_type,
 	.size           = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
 	.eval           = nft_nat_eval,
 	.init           = nft_nat_init,
+	.destroy        = nft_nat_destroy,
 	.dump           = nft_nat_dump,
 	.validate	= nft_nat_validate,
 };
diff --git a/net/netfilter/nft_redir.c b/net/netfilter/nft_redir.c
index 03f7bf40ae75..f8227ec44419 100644
--- a/net/netfilter/nft_redir.c
+++ b/net/netfilter/nft_redir.c
@@ -79,7 +79,7 @@ int nft_redir_init(const struct nft_ctx *ctx,
 			return -EINVAL;
 	}
 
-	return 0;
+	return nf_ct_netns_get(ctx->net, ctx->afi->family);
 }
 EXPORT_SYMBOL_GPL(nft_redir_init);
 
-- 
2.7.3

[PATCH v4 nf-next 5/7] netfilter: conntrack: register hooks in netns when needed by ruleset

[Florian Westphal]

This makes use of nf_ct_netns_get/put added in previous patch.
We add get/put functions to nf_conntrack_l3proto structure, ipv4 and ipv6
then implement use-count to track how many users (nft or xtables modules)
have a dependency on ipv4 and/or ipv6 connection tracking functionality.

When count reaches zero, the hooks are unregistered.

This delays activation of connection tracking inside a namespace until
stateful firewall rule or nat rule gets added.

This patch breaks backwards compatibility in the sense that connection
tracking won't be active anymore when the protocol tracker module is
loaded.  This breaks e.g. setups that ctnetlink for flow accounting and
the like, without any '-m conntrack' packet filter rules.

Followup patch restores old behavour and makes new delayed scheme
optional via sysctl.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 No changes since v3.

 include/net/netfilter/nf_conntrack_l3proto.h   |  4 ++
 net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c | 55 ++++++++++++++++++++------
 net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c | 54 +++++++++++++++++++------
 net/netfilter/nf_conntrack_proto.c             | 38 +++++++++++++++++-
 4 files changed, 127 insertions(+), 24 deletions(-)

diff --git a/include/net/netfilter/nf_conntrack_l3proto.h b/include/net/netfilter/nf_conntrack_l3proto.h
index cf8f3dfd810d..e7dcd72be21c 100644
--- a/include/net/netfilter/nf_conntrack_l3proto.h
+++ b/include/net/netfilter/nf_conntrack_l3proto.h
@@ -52,6 +52,10 @@ struct nf_conntrack_l3proto {
 	int (*tuple_to_nlattr)(struct sk_buff *skb,
 			       const struct nf_conntrack_tuple *t);
 
+	/* Called when netns wants to use connection tracking */
+	int (*net_ns_get)(struct net *);
+	void (*net_ns_put)(struct net *);
+
 	/*
 	 * Calculate size of tuple nlattr
 	 */
diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
index 823cf3331b9d..999d47bd2c9f 100644
--- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
+++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
@@ -31,6 +31,13 @@
 #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)
 {
@@ -307,6 +314,38 @@ static struct nf_sockopt_ops so_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(&register_ipv4_hooks);
+
+	cnet->users++;
+	if (cnet->users > 1)
+		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(&register_ipv4_hooks);
+	return err;
+}
+
+static void ipv4_hooks_unregister(struct net *net)
+{
+	struct conntrack4_net *cnet = net_generic(net, conntrack4_net_id);
+
+	mutex_lock(&register_ipv4_hooks);
+	if (cnet->users && (--cnet->users == 0))
+		nf_unregister_net_hooks(net, ipv4_conntrack_ops,
+					ARRAY_SIZE(ipv4_conntrack_ops));
+	mutex_unlock(&register_ipv4_hooks);
+}
+
 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 __read_mostly = {
 	.l3proto	 = PF_INET,
 	.name		 = "ipv4",
@@ -320,6 +359,8 @@ struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 __read_mostly = {
 	.nlattr_to_tuple = ipv4_nlattr_to_tuple,
 	.nla_policy	 = ipv4_nla_policy,
 #endif
+	.net_ns_get	 = ipv4_hooks_register,
+	.net_ns_put	 = ipv4_hooks_unregister,
 	.me		 = THIS_MODULE,
 };
 
@@ -363,6 +404,8 @@ static void ipv4_net_exit(struct net *net)
 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)
@@ -384,17 +427,10 @@ static int __init nf_conntrack_l3proto_ipv4_init(void)
 		goto cleanup_sockopt;
 	}
 
-	ret = nf_register_hooks(ipv4_conntrack_ops,
-				ARRAY_SIZE(ipv4_conntrack_ops));
-	if (ret < 0) {
-		pr_err("nf_conntrack_ipv4: can't register hooks.\n");
-		goto cleanup_pernet;
-	}
-
 	ret = nf_ct_l4proto_register(builtin_l4proto4,
 				     ARRAY_SIZE(builtin_l4proto4));
 	if (ret < 0)
-		goto cleanup_hooks;
+		goto cleanup_pernet;
 
 	ret = nf_ct_l3proto_register(&nf_conntrack_l3proto_ipv4);
 	if (ret < 0) {
@@ -406,8 +442,6 @@ static int __init nf_conntrack_l3proto_ipv4_init(void)
 cleanup_l4proto:
 	nf_ct_l4proto_unregister(builtin_l4proto4,
 				 ARRAY_SIZE(builtin_l4proto4));
- cleanup_hooks:
-	nf_unregister_hooks(ipv4_conntrack_ops, ARRAY_SIZE(ipv4_conntrack_ops));
  cleanup_pernet:
 	unregister_pernet_subsys(&ipv4_net_ops);
  cleanup_sockopt:
@@ -421,7 +455,6 @@ static void __exit nf_conntrack_l3proto_ipv4_fini(void)
 	nf_ct_l3proto_unregister(&nf_conntrack_l3proto_ipv4);
 	nf_ct_l4proto_unregister(builtin_l4proto4,
 				 ARRAY_SIZE(builtin_l4proto4));
-	nf_unregister_hooks(ipv4_conntrack_ops, ARRAY_SIZE(ipv4_conntrack_ops));
 	unregister_pernet_subsys(&ipv4_net_ops);
 	nf_unregister_sockopt(&so_getorigdst);
 }
diff --git a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
index 500be28ff563..7582a24704f4 100644
--- a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
+++ b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
@@ -34,6 +34,13 @@
 #include <net/netfilter/ipv6/nf_defrag_ipv6.h>
 #include <net/netfilter/nf_log.h>
 
+static int conntrack6_net_id;
+static DEFINE_MUTEX(register_ipv6_hooks);
+
+struct conntrack6_net {
+	unsigned int users;
+};
+
 static bool ipv6_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
 			      struct nf_conntrack_tuple *tuple)
 {
@@ -308,6 +315,36 @@ static int ipv6_nlattr_tuple_size(void)
 }
 #endif
 
+static int ipv6_hooks_register(struct net *net)
+{
+	struct conntrack6_net *cnet = net_generic(net, conntrack6_net_id);
+	int err = 0;
+
+	mutex_lock(&register_ipv6_hooks);
+	cnet->users++;
+	if (cnet->users > 1)
+		goto out_unlock;
+
+	err = nf_register_net_hooks(net, ipv6_conntrack_ops,
+				    ARRAY_SIZE(ipv6_conntrack_ops));
+	if (err)
+		cnet->users = 0;
+ out_unlock:
+	mutex_unlock(&register_ipv6_hooks);
+	return err;
+}
+
+static void ipv6_hooks_unregister(struct net *net)
+{
+	struct conntrack6_net *cnet = net_generic(net, conntrack6_net_id);
+
+	mutex_lock(&register_ipv6_hooks);
+	if (cnet->users && (--cnet->users == 0))
+		nf_unregister_net_hooks(net, ipv6_conntrack_ops,
+					ARRAY_SIZE(ipv6_conntrack_ops));
+	mutex_unlock(&register_ipv6_hooks);
+}
+
 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 __read_mostly = {
 	.l3proto		= PF_INET6,
 	.name			= "ipv6",
@@ -321,6 +358,8 @@ struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 __read_mostly = {
 	.nlattr_to_tuple	= ipv6_nlattr_to_tuple,
 	.nla_policy		= ipv6_nla_policy,
 #endif
+	.net_ns_get		= ipv6_hooks_register,
+	.net_ns_put		= ipv6_hooks_unregister,
 	.me			= THIS_MODULE,
 };
 
@@ -370,6 +409,8 @@ static void ipv6_net_exit(struct net *net)
 static struct pernet_operations ipv6_net_ops = {
 	.init = ipv6_net_init,
 	.exit = ipv6_net_exit,
+	.id = &conntrack6_net_id,
+	.size = sizeof(struct conntrack6_net),
 };
 
 static int __init nf_conntrack_l3proto_ipv6_init(void)
@@ -389,18 +430,10 @@ static int __init nf_conntrack_l3proto_ipv6_init(void)
 	if (ret < 0)
 		goto cleanup_sockopt;
 
-	ret = nf_register_hooks(ipv6_conntrack_ops,
-				ARRAY_SIZE(ipv6_conntrack_ops));
-	if (ret < 0) {
-		pr_err("nf_conntrack_ipv6: can't register pre-routing defrag "
-		       "hook.\n");
-		goto cleanup_pernet;
-	}
-
 	ret = nf_ct_l4proto_register(builtin_l4proto6,
 				     ARRAY_SIZE(builtin_l4proto6));
 	if (ret < 0)
-		goto cleanup_hooks;
+		goto cleanup_pernet;
 
 	ret = nf_ct_l3proto_register(&nf_conntrack_l3proto_ipv6);
 	if (ret < 0) {
@@ -411,8 +444,6 @@ static int __init nf_conntrack_l3proto_ipv6_init(void)
 cleanup_l4proto:
 	nf_ct_l4proto_unregister(builtin_l4proto6,
 				 ARRAY_SIZE(builtin_l4proto6));
- cleanup_hooks:
-	nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
  cleanup_pernet:
 	unregister_pernet_subsys(&ipv6_net_ops);
  cleanup_sockopt:
@@ -426,7 +457,6 @@ static void __exit nf_conntrack_l3proto_ipv6_fini(void)
 	nf_ct_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
 	nf_ct_l4proto_unregister(builtin_l4proto6,
 				 ARRAY_SIZE(builtin_l4proto6));
-	nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
 	unregister_pernet_subsys(&ipv6_net_ops);
 	nf_unregister_sockopt(&so_getorigdst6);
 }
diff --git a/net/netfilter/nf_conntrack_proto.c b/net/netfilter/nf_conntrack_proto.c
index 948f1e2fc80b..758688b25fd8 100644
--- a/net/netfilter/nf_conntrack_proto.c
+++ b/net/netfilter/nf_conntrack_proto.c
@@ -127,12 +127,48 @@ EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
 
 int nf_ct_netns_get(struct net *net, u8 nfproto)
 {
-	return nf_ct_l3proto_try_module_get(nfproto);
+	const struct nf_conntrack_l3proto *l3proto;
+	int ret;
+
+	might_sleep();
+
+	ret = nf_ct_l3proto_try_module_get(nfproto);
+	if (ret < 0)
+		return ret;
+
+	/* we already have a reference, can't fail */
+	rcu_read_lock();
+	l3proto = __nf_ct_l3proto_find(nfproto);
+	rcu_read_unlock();
+
+	if (!l3proto->net_ns_get)
+		return 0;
+
+	ret = l3proto->net_ns_get(net);
+	if (ret < 0)
+		nf_ct_l3proto_module_put(nfproto);
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(nf_ct_netns_get);
 
 void nf_ct_netns_put(struct net *net, u8 nfproto)
 {
+	const struct nf_conntrack_l3proto *l3proto;
+
+	might_sleep();
+
+	/* same as nf_conntrack_netns_get(), reference assumed */
+	rcu_read_lock();
+	l3proto = __nf_ct_l3proto_find(nfproto);
+	rcu_read_unlock();
+
+	if (WARN_ON(!l3proto))
+		return;
+
+	if (l3proto->net_ns_put)
+		l3proto->net_ns_put(net);
+
 	nf_ct_l3proto_module_put(nfproto);
 }
 EXPORT_SYMBOL_GPL(nf_ct_netns_put);
-- 
2.7.3

[PATCH nf-next 6/7] conntrack: add nf_conntrack_default_on sysctl

[Florian Westphal]

This switch (default on) can be used to disable automatic registration
of connection tracking functionality in newly created network
namespaces.

This means that when net namespace goes down (or the tracker protocol
module is unloaded) we *might* have to unregister the hooks.

We can either add another per-netns variable that tells if
the hooks got registered by default, or, alternatively, just call
the protocol _put() function and have the callee deal with a possible
'extra' put() operation that doesn't pair with a get() one.

This uses the latter approach, i.e. a put() without a get has no effect.

Conntrack is still enabled automatically regardless of the new sysctl
setting if the new net namespace requires connection tracking, e.g. when
NAT rules are created.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 This patch was not part of earlier series version.

 Documentation/networking/nf_conntrack-sysctl.txt | 11 +++++++++++
 include/net/netfilter/nf_conntrack_l3proto.h     |  9 +++++++++
 net/netfilter/nf_conntrack_proto.c               | 19 ++++++++++++++++++-
 net/netfilter/nf_conntrack_standalone.c          | 10 ++++++++++
 4 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/Documentation/networking/nf_conntrack-sysctl.txt b/Documentation/networking/nf_conntrack-sysctl.txt
index 399e4e866a9c..cdeb9d6a44c7 100644
--- a/Documentation/networking/nf_conntrack-sysctl.txt
+++ b/Documentation/networking/nf_conntrack-sysctl.txt
@@ -93,6 +93,17 @@ nf_conntrack_max - INTEGER
 	Size of connection tracking table.  Default value is
 	nf_conntrack_buckets value * 4.
 
+nf_conntrack_default_on - BOOLEAN
+	0 - don't register conntrack in new net namespaces
+	1 - register conntrack in new net namespaces (default)
+
+	This controls wheter newly created network namespaces have connection
+	tracking enabled by default.  It will be enabled automatically
+	regardless of this setting if the new net namespace requires
+	connection tracking, e.g. when NAT rules are created.
+	This setting is only visible in initial user namespace, it has no
+	effect on existing namespaces.
+
 nf_conntrack_tcp_be_liberal - BOOLEAN
 	0 - disabled (default)
 	not 0 - enabled
diff --git a/include/net/netfilter/nf_conntrack_l3proto.h b/include/net/netfilter/nf_conntrack_l3proto.h
index e7dcd72be21c..e01559b4d781 100644
--- a/include/net/netfilter/nf_conntrack_l3proto.h
+++ b/include/net/netfilter/nf_conntrack_l3proto.h
@@ -73,9 +73,18 @@ struct nf_conntrack_l3proto {
 
 extern struct nf_conntrack_l3proto __rcu *nf_ct_l3protos[AF_MAX];
 
+#ifdef CONFIG_SYSCTL
 /* Protocol pernet registration. */
 int nf_ct_l3proto_pernet_register(struct net *net,
 				  struct nf_conntrack_l3proto *proto);
+#else
+static inline int nf_ct_l3proto_pernet_register(struct net *n,
+						struct nf_conntrack_l3proto *p)
+{
+	return 0;
+}
+#endif
+
 void nf_ct_l3proto_pernet_unregister(struct net *net,
 				     struct nf_conntrack_l3proto *proto);
 
diff --git a/net/netfilter/nf_conntrack_proto.c b/net/netfilter/nf_conntrack_proto.c
index 758688b25fd8..2d6ee1803415 100644
--- a/net/netfilter/nf_conntrack_proto.c
+++ b/net/netfilter/nf_conntrack_proto.c
@@ -238,12 +238,19 @@ int nf_ct_l3proto_register(struct nf_conntrack_l3proto *proto)
 }
 EXPORT_SYMBOL_GPL(nf_ct_l3proto_register);
 
+#ifdef CONFIG_SYSCTL
+extern unsigned int nf_conntrack_default_on;
+
 int nf_ct_l3proto_pernet_register(struct net *net,
 				  struct nf_conntrack_l3proto *proto)
 {
-	return 0;
+	if (nf_conntrack_default_on == 0)
+		return 0;
+
+	return proto->net_ns_get ? proto->net_ns_get(net) : 0;
 }
 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_register);
+#endif
 
 void nf_ct_l3proto_unregister(struct nf_conntrack_l3proto *proto)
 {
@@ -264,6 +271,16 @@ EXPORT_SYMBOL_GPL(nf_ct_l3proto_unregister);
 void nf_ct_l3proto_pernet_unregister(struct net *net,
 				     struct nf_conntrack_l3proto *proto)
 {
+	/*
+	 * nf_conntrack_default_on *might* have registered hooks.
+	 * ->net_ns_put must cope with more puts() than get(), i.e.
+	 * if nf_conntrack_default_on was 0 at time of
+	 * nf_ct_l3proto_pernet_register invocation this net_ns_put()
+	 * should be a noop.
+	 */
+	if (proto->net_ns_put)
+		proto->net_ns_put(net);
+
 	/* Remove all contrack entries for this protocol */
 	nf_ct_iterate_cleanup(net, kill_l3proto, proto, 0, 0);
 }
diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
index 5f446cd9f3fd..d009ae663453 100644
--- a/net/netfilter/nf_conntrack_standalone.c
+++ b/net/netfilter/nf_conntrack_standalone.c
@@ -452,6 +452,9 @@ static int log_invalid_proto_max __read_mostly = 255;
 /* size the user *wants to set */
 static unsigned int nf_conntrack_htable_size_user __read_mostly;
 
+extern unsigned int nf_conntrack_default_on;
+unsigned int nf_conntrack_default_on __read_mostly = 1;
+
 static int
 nf_conntrack_hash_sysctl(struct ctl_table *table, int write,
 			 void __user *buffer, size_t *lenp, loff_t *ppos)
@@ -517,6 +520,13 @@ static struct ctl_table nf_ct_sysctl_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
+	{
+		.procname	= "nf_conntrack_default_on",
+		.data		= &nf_conntrack_default_on,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
 	{ }
 };
 
-- 
2.7.3

[PATCH v4 nf-next 7/7] netfilter: defrag: only register defrag functionality if needed

[Florian Westphal]

nf_defrag modules for ipv4 and ipv6 export an empty stub function.
Any module that needs the defragmentation hooks registered simply 'calls'
this empty function to create a phony module dependency -- modprobe will
then load the defrag module too.

This extends netfilter ipv4/ipv6 defragmentation modules to delay the hook
registration until the functionality is requested within a network namespace
instead of module load time for all namespaces.

Hooks are only un-registered on module unload or when a namespace that used
such defrag functionality exits.

We have to use struct net for this as the register hooks can be called
before netns initialization here from the ipv4/ipv6 conntrack module
init path.

There is no unregister functionality support, defrag will always be
active once it was requested inside a net namespace.

The reason is that defrag has impact on nft and iptables rulesets
(without defrag we might see framents).

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 Changes since v3: place 'defrag_ipv4' in netns_ct, see above

 include/net/netfilter/ipv4/nf_defrag_ipv4.h    |  3 +-
 include/net/netfilter/ipv6/nf_defrag_ipv6.h    |  3 +-
 include/net/netns/conntrack.h                  |  2 ++
 net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c |  7 ++++-
 net/ipv4/netfilter/nf_defrag_ipv4.c            | 41 +++++++++++++++++++++++--
 net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c |  7 ++++-
 net/ipv6/netfilter/nf_defrag_ipv6_hooks.c      | 42 +++++++++++++++++++++++---
 net/netfilter/xt_TPROXY.c                      | 15 ++++++---
 net/netfilter/xt_socket.c                      | 33 +++++++++++++++++---
 9 files changed, 132 insertions(+), 21 deletions(-)

diff --git a/include/net/netfilter/ipv4/nf_defrag_ipv4.h b/include/net/netfilter/ipv4/nf_defrag_ipv4.h
index f01ef208dff6..db405f70e538 100644
--- a/include/net/netfilter/ipv4/nf_defrag_ipv4.h
+++ b/include/net/netfilter/ipv4/nf_defrag_ipv4.h
@@ -1,6 +1,7 @@
 #ifndef _NF_DEFRAG_IPV4_H
 #define _NF_DEFRAG_IPV4_H
 
-void nf_defrag_ipv4_enable(void);
+struct net;
+int nf_defrag_ipv4_enable(struct net *);
 
 #endif /* _NF_DEFRAG_IPV4_H */
diff --git a/include/net/netfilter/ipv6/nf_defrag_ipv6.h b/include/net/netfilter/ipv6/nf_defrag_ipv6.h
index ddf162f7966f..7664efe37974 100644
--- a/include/net/netfilter/ipv6/nf_defrag_ipv6.h
+++ b/include/net/netfilter/ipv6/nf_defrag_ipv6.h
@@ -1,7 +1,8 @@
 #ifndef _NF_DEFRAG_IPV6_H
 #define _NF_DEFRAG_IPV6_H
 
-void nf_defrag_ipv6_enable(void);
+struct net;
+int nf_defrag_ipv6_enable(struct net *);
 
 int nf_ct_frag6_init(void);
 void nf_ct_frag6_cleanup(void);
diff --git a/include/net/netns/conntrack.h b/include/net/netns/conntrack.h
index 3d06d94d2e52..f0e14a6cc13f 100644
--- a/include/net/netns/conntrack.h
+++ b/include/net/netns/conntrack.h
@@ -81,6 +81,8 @@ struct netns_ct {
 	int			sysctl_acct;
 	int			sysctl_auto_assign_helper;
 	bool			auto_assign_helper_warned;
+	bool			defrag_ipv4;
+	bool			defrag_ipv6;
 	int			sysctl_tstamp;
 	int			sysctl_checksum;
 
diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
index 999d47bd2c9f..9de5d822f21b 100644
--- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
+++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
@@ -325,6 +325,12 @@ static int ipv4_hooks_register(struct net *net)
 	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));
 
@@ -413,7 +419,6 @@ static int __init nf_conntrack_l3proto_ipv4_init(void)
 	int ret = 0;
 
 	need_conntrack();
-	nf_defrag_ipv4_enable();
 
 	ret = nf_register_sockopt(&so_getorigdst);
 	if (ret < 0) {
diff --git a/net/ipv4/netfilter/nf_defrag_ipv4.c b/net/ipv4/netfilter/nf_defrag_ipv4.c
index d88da36b383c..8f72e4f172be 100644
--- a/net/ipv4/netfilter/nf_defrag_ipv4.c
+++ b/net/ipv4/netfilter/nf_defrag_ipv4.c
@@ -11,6 +11,7 @@
 #include <linux/netfilter.h>
 #include <linux/module.h>
 #include <linux/skbuff.h>
+#include <net/netns/generic.h>
 #include <net/route.h>
 #include <net/ip.h>
 
@@ -22,6 +23,8 @@
 #endif
 #include <net/netfilter/nf_conntrack_zones.h>
 
+static DEFINE_MUTEX(defrag4_mutex);
+
 static int nf_ct_ipv4_gather_frags(struct net *net, struct sk_buff *skb,
 				   u_int32_t user)
 {
@@ -102,18 +105,50 @@ static struct nf_hook_ops ipv4_defrag_ops[] = {
 	},
 };
 
+static void __net_exit defrag4_net_exit(struct net *net)
+{
+	if (net->ct.defrag_ipv4) {
+		nf_unregister_net_hooks(net, ipv4_defrag_ops,
+					ARRAY_SIZE(ipv4_defrag_ops));
+		net->ct.defrag_ipv4 = false;
+	}
+}
+
+static struct pernet_operations defrag4_net_ops = {
+	.exit = defrag4_net_exit,
+};
+
 static int __init nf_defrag_init(void)
 {
-	return nf_register_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
+	return register_pernet_subsys(&defrag4_net_ops);
 }
 
 static void __exit nf_defrag_fini(void)
 {
-	nf_unregister_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
+	unregister_pernet_subsys(&defrag4_net_ops);
 }
 
-void nf_defrag_ipv4_enable(void)
+int nf_defrag_ipv4_enable(struct net *net)
 {
+	int err = 0;
+
+	might_sleep();
+
+	if (net->ct.defrag_ipv4)
+		return 0;
+
+	mutex_lock(&defrag4_mutex);
+	if (net->ct.defrag_ipv4)
+		goto out_unlock;
+
+	err = nf_register_net_hooks(net, ipv4_defrag_ops,
+				    ARRAY_SIZE(ipv4_defrag_ops));
+	if (err == 0)
+		net->ct.defrag_ipv4 = true;
+
+ out_unlock:
+	mutex_unlock(&defrag4_mutex);
+	return err;
 }
 EXPORT_SYMBOL_GPL(nf_defrag_ipv4_enable);
 
diff --git a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
index 7582a24704f4..5f59413ce019 100644
--- a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
+++ b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
@@ -325,6 +325,12 @@ static int ipv6_hooks_register(struct net *net)
 	if (cnet->users > 1)
 		goto out_unlock;
 
+	err = nf_defrag_ipv6_enable(net);
+	if (err < 0) {
+		cnet->users = 0;
+		goto out_unlock;
+	}
+
 	err = nf_register_net_hooks(net, ipv6_conntrack_ops,
 				    ARRAY_SIZE(ipv6_conntrack_ops));
 	if (err)
@@ -418,7 +424,6 @@ static int __init nf_conntrack_l3proto_ipv6_init(void)
 	int ret = 0;
 
 	need_conntrack();
-	nf_defrag_ipv6_enable();
 
 	ret = nf_register_sockopt(&so_getorigdst6);
 	if (ret < 0) {
diff --git a/net/ipv6/netfilter/nf_defrag_ipv6_hooks.c b/net/ipv6/netfilter/nf_defrag_ipv6_hooks.c
index f7aab5ab93a5..9e552ff8bc89 100644
--- a/net/ipv6/netfilter/nf_defrag_ipv6_hooks.c
+++ b/net/ipv6/netfilter/nf_defrag_ipv6_hooks.c
@@ -30,6 +30,8 @@
 #include <net/netfilter/nf_conntrack_zones.h>
 #include <net/netfilter/ipv6/nf_defrag_ipv6.h>
 
+static DEFINE_MUTEX(defrag6_mutex);
+
 static enum ip6_defrag_users nf_ct6_defrag_user(unsigned int hooknum,
 						struct sk_buff *skb)
 {
@@ -87,6 +89,19 @@ static struct nf_hook_ops ipv6_defrag_ops[] = {
 	},
 };
 
+static void __net_exit defrag6_net_exit(struct net *net)
+{
+	if (net->ct.defrag_ipv6) {
+		nf_unregister_net_hooks(net, ipv6_defrag_ops,
+					ARRAY_SIZE(ipv6_defrag_ops));
+		net->ct.defrag_ipv6 = false;
+	}
+}
+
+static struct pernet_operations defrag6_net_ops = {
+	.exit = defrag6_net_exit,
+};
+
 static int __init nf_defrag_init(void)
 {
 	int ret = 0;
@@ -96,9 +111,9 @@ static int __init nf_defrag_init(void)
 		pr_err("nf_defrag_ipv6: can't initialize frag6.\n");
 		return ret;
 	}
-	ret = nf_register_hooks(ipv6_defrag_ops, ARRAY_SIZE(ipv6_defrag_ops));
+	ret = register_pernet_subsys(&defrag6_net_ops);
 	if (ret < 0) {
-		pr_err("nf_defrag_ipv6: can't register hooks\n");
+		pr_err("nf_defrag_ipv6: can't register pernet ops\n");
 		goto cleanup_frag6;
 	}
 	return ret;
@@ -111,12 +126,31 @@ static int __init nf_defrag_init(void)
 
 static void __exit nf_defrag_fini(void)
 {
-	nf_unregister_hooks(ipv6_defrag_ops, ARRAY_SIZE(ipv6_defrag_ops));
+	unregister_pernet_subsys(&defrag6_net_ops);
 	nf_ct_frag6_cleanup();
 }
 
-void nf_defrag_ipv6_enable(void)
+int nf_defrag_ipv6_enable(struct net *net)
 {
+	int err = 0;
+
+	might_sleep();
+
+	if (net->ct.defrag_ipv6)
+		return 0;
+
+	mutex_lock(&defrag6_mutex);
+	if (net->ct.defrag_ipv6)
+		goto out_unlock;
+
+	err = nf_register_net_hooks(net, ipv6_defrag_ops,
+				    ARRAY_SIZE(ipv6_defrag_ops));
+	if (err == 0)
+		net->ct.defrag_ipv6 = true;
+
+ out_unlock:
+	mutex_unlock(&defrag6_mutex);
+	return err;
 }
 EXPORT_SYMBOL_GPL(nf_defrag_ipv6_enable);
 
diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
index dbd72cc40e42..80cb7babeb64 100644
--- a/net/netfilter/xt_TPROXY.c
+++ b/net/netfilter/xt_TPROXY.c
@@ -531,6 +531,11 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
 static int tproxy_tg6_check(const struct xt_tgchk_param *par)
 {
 	const struct ip6t_ip6 *i = par->entryinfo;
+	int err;
+
+	err = nf_defrag_ipv6_enable(par->net);
+	if (err)
+		return err;
 
 	if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP) &&
 	    !(i->invflags & IP6T_INV_PROTO))
@@ -545,6 +550,11 @@ static int tproxy_tg6_check(const struct xt_tgchk_param *par)
 static int tproxy_tg4_check(const struct xt_tgchk_param *par)
 {
 	const struct ipt_ip *i = par->entryinfo;
+	int err;
+
+	err = nf_defrag_ipv4_enable(par->net);
+	if (err)
+		return err;
 
 	if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP)
 	    && !(i->invflags & IPT_INV_PROTO))
@@ -596,11 +606,6 @@ static struct xt_target tproxy_tg_reg[] __read_mostly = {
 
 static int __init tproxy_tg_init(void)
 {
-	nf_defrag_ipv4_enable();
-#ifdef XT_TPROXY_HAVE_IPV6
-	nf_defrag_ipv6_enable();
-#endif
-
 	return xt_register_targets(tproxy_tg_reg, ARRAY_SIZE(tproxy_tg_reg));
 }
 
diff --git a/net/netfilter/xt_socket.c b/net/netfilter/xt_socket.c
index 2198914707f5..770bbec878f1 100644
--- a/net/netfilter/xt_socket.c
+++ b/net/netfilter/xt_socket.c
@@ -147,9 +147,28 @@ socket_mt6_v1_v2_v3(const struct sk_buff *skb, struct xt_action_param *par)
 }
 #endif
 
+static int socket_mt_enable_defrag(struct net *net, int family)
+{
+	switch (family) {
+	case NFPROTO_IPV4:
+		return nf_defrag_ipv4_enable(net);
+#ifdef XT_SOCKET_HAVE_IPV6
+	case NFPROTO_IPV6:
+		return nf_defrag_ipv6_enable(net);
+#endif
+	}
+	WARN_ONCE(1, "Unknown family %d\n", family);
+	return 0;
+}
+
 static int socket_mt_v1_check(const struct xt_mtchk_param *par)
 {
 	const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo;
+	int err;
+
+	err = socket_mt_enable_defrag(par->net, par->family);
+	if (err)
+		return err;
 
 	if (info->flags & ~XT_SOCKET_FLAGS_V1) {
 		pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V1);
@@ -161,6 +180,11 @@ static int socket_mt_v1_check(const struct xt_mtchk_param *par)
 static int socket_mt_v2_check(const struct xt_mtchk_param *par)
 {
 	const struct xt_socket_mtinfo2 *info = (struct xt_socket_mtinfo2 *) par->matchinfo;
+	int err;
+
+	err = socket_mt_enable_defrag(par->net, par->family);
+	if (err)
+		return err;
 
 	if (info->flags & ~XT_SOCKET_FLAGS_V2) {
 		pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V2);
@@ -173,7 +197,11 @@ static int socket_mt_v3_check(const struct xt_mtchk_param *par)
 {
 	const struct xt_socket_mtinfo3 *info =
 				    (struct xt_socket_mtinfo3 *)par->matchinfo;
+	int err;
 
+	err = socket_mt_enable_defrag(par->net, par->family);
+	if (err)
+		return err;
 	if (info->flags & ~XT_SOCKET_FLAGS_V3) {
 		pr_info("unknown flags 0x%x\n",
 			info->flags & ~XT_SOCKET_FLAGS_V3);
@@ -268,11 +296,6 @@ static struct xt_match socket_mt_reg[] __read_mostly = {
 
 static int __init socket_mt_init(void)
 {
-	nf_defrag_ipv4_enable();
-#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
-	nf_defrag_ipv6_enable();
-#endif
-
 	return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
 }
 
-- 
2.7.3

Re: [PATCH v4 nf-next] netfilter: allow disabling conntrack-on-by-default

[Pablo Neira Ayuso]

On Tue, Nov 15, 2016 at 09:36:38PM +0100, Florian Westphal wrote:
> Historically all the netfilter hooks got registered on module load time.
> 
> When net namespace support was added, hooks were registered in each
> namespace (and new net namespaces inherit already-registered hooks from
> global list).
> 
> This means that once nf_conntrack_ipv4/6.ko is loaded, all
> existing and future net namespaces do connection tracking.
> 
> This series adds a new sysctl, nf_conntrack_default_on, that can be set
> to 0 to disable this behaviour.
> 
> Once its set to 0, conntrack hooks are not registered in newly created
> net namespaces, and new l3 protocol trackers are not registered with any
> existing namespaces either.
> 
> The setting does NOT disable already-active connection tracking
> in existing namespaces.
> 
> connection tracking is enabled via packet filter ruleset, regardless of
> the sysctl setting, once a rule that needs conntrack functionality is
> added (e.g. iptables -m conntrack, targets like SNAT/DNAT or nftables
> equivalents make sure the hooks get registered, and deleted, as needed).
> 
> It is currently NOT possible to disable connection tracking inside a
> net namespace that had its hooks registered implicitly due to
> nf_conntrack_default_on=1 (except unloading the l3 tracker module).

Series applied, thanks Florian.