[PATCH nf-next 0/3] netfilter: clusterip: don't register hook in all netns

[PATCH nf-next 0/3] netfilter: clusterip: don't register hook in all netns

[Florian Westphal]

This series stops ipt_CLUSTERIP from registering arp mangling hook
unconditionally.

Hook gets installed/removed from checkentry/destroy callbacks.

Before this, modprobe ipt_CLUSTERIP would add a hook in each netns.
While at it, also get rid of x_tables.h/xt storage space in struct net,
there is no need for this.

Florian Westphal (3):
  netfilter: ipt_CLUSTERIP: only add arp mangle hook when required
  netfilter: ipt_CLUSTERIP: use clusterip_net to store pernet warning
  netfilter: remove xt pernet data

 include/net/net_namespace.h        |  2 --
 include/net/netns/x_tables.h       | 12 -------
 net/ipv4/netfilter/ipt_CLUSTERIP.c | 56 ++++++++++++++++++++----------
 net/netfilter/xt_CT.c              | 11 ------
 4 files changed, 37 insertions(+), 44 deletions(-)
 delete mode 100644 include/net/netns/x_tables.h

-- 
2.31.1

[PATCH nf-next 1/3] netfilter: ipt_CLUSTERIP: only add arp mangle hook when required

[Florian Westphal]

Do not register the arp mangling hooks from pernet init path.

As-is, load of the module is enough for these hooks to become active
in each net namespace.

Use checkentry instead so hook is only added if a CLUSTERIP rule is used.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/ipv4/netfilter/ipt_CLUSTERIP.c | 51 ++++++++++++++++++++----------
 1 file changed, 34 insertions(+), 17 deletions(-)

diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c
index 8f7ca67475b7..11bcf599358d 100644
--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
+++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
@@ -71,6 +71,16 @@ struct clusterip_net {
 	/* mutex protects the config->pde*/
 	struct mutex mutex;
 #endif
+	unsigned int hook_users;
+};
+
+static unsigned int clusterip_arp_mangle(void *priv, struct sk_buff *skb, const struct nf_hook_state *state);
+
+static const struct nf_hook_ops cip_arp_ops = {
+	.hook = clusterip_arp_mangle,
+	.pf = NFPROTO_ARP,
+	.hooknum = NF_ARP_OUT,
+	.priority = -1
 };
 
 static unsigned int clusterip_net_id __read_mostly;
@@ -458,6 +468,7 @@ clusterip_tg(struct sk_buff *skb, const struct xt_action_param *par)
 static int clusterip_tg_check(const struct xt_tgchk_param *par)
 {
 	struct ipt_clusterip_tgt_info *cipinfo = par->targinfo;
+	struct clusterip_net *cn = clusterip_pernet(par->net);
 	const struct ipt_entry *e = par->entryinfo;
 	struct clusterip_config *config;
 	int ret, i;
@@ -467,6 +478,9 @@ static int clusterip_tg_check(const struct xt_tgchk_param *par)
 		return -EOPNOTSUPP;
 	}
 
+	if (cn->hook_users == UINT_MAX)
+		return -EOVERFLOW;
+
 	if (cipinfo->hash_mode != CLUSTERIP_HASHMODE_SIP &&
 	    cipinfo->hash_mode != CLUSTERIP_HASHMODE_SIP_SPT &&
 	    cipinfo->hash_mode != CLUSTERIP_HASHMODE_SIP_SPT_DPT) {
@@ -517,6 +531,19 @@ static int clusterip_tg_check(const struct xt_tgchk_param *par)
 		return ret;
 	}
 
+	if (cn->hook_users == 0) {
+		ret = nf_register_net_hook(par->net, &cip_arp_ops);
+
+		if (ret < 0) {
+			clusterip_config_entry_put(cipinfo->config);
+			clusterip_config_put(cipinfo->config);
+			nf_ct_netns_put(par->net, par->family);
+			return ret;
+		}
+	}
+
+	cn->hook_users++;
+
 	if (!par->net->xt.clusterip_deprecated_warning) {
 		pr_info("ipt_CLUSTERIP is deprecated and it will removed soon, "
 			"use xt_cluster instead\n");
@@ -531,6 +558,7 @@ static int clusterip_tg_check(const struct xt_tgchk_param *par)
 static void clusterip_tg_destroy(const struct xt_tgdtor_param *par)
 {
 	const struct ipt_clusterip_tgt_info *cipinfo = par->targinfo;
+	struct clusterip_net *cn = clusterip_pernet(par->net);
 
 	/* if no more entries are referencing the config, remove it
 	 * from the list and destroy the proc entry */
@@ -539,6 +567,10 @@ static void clusterip_tg_destroy(const struct xt_tgdtor_param *par)
 	clusterip_config_put(cipinfo->config);
 
 	nf_ct_netns_put(par->net, par->family);
+	cn->hook_users--;
+
+	if (cn->hook_users == 0)
+		nf_unregister_net_hook(par->net, &cip_arp_ops);
 }
 
 #ifdef CONFIG_NETFILTER_XTABLES_COMPAT
@@ -602,9 +634,8 @@ static void arp_print(struct arp_payload *payload)
 #endif
 
 static unsigned int
-arp_mangle(void *priv,
-	   struct sk_buff *skb,
-	   const struct nf_hook_state *state)
+clusterip_arp_mangle(void *priv, struct sk_buff *skb,
+		     const struct nf_hook_state *state)
 {
 	struct arphdr *arp = arp_hdr(skb);
 	struct arp_payload *payload;
@@ -654,13 +685,6 @@ arp_mangle(void *priv,
 	return NF_ACCEPT;
 }
 
-static const struct nf_hook_ops cip_arp_ops = {
-	.hook = arp_mangle,
-	.pf = NFPROTO_ARP,
-	.hooknum = NF_ARP_OUT,
-	.priority = -1
-};
-
 /***********************************************************************
  * PROC DIR HANDLING
  ***********************************************************************/
@@ -817,20 +841,14 @@ static const struct proc_ops clusterip_proc_ops = {
 static int clusterip_net_init(struct net *net)
 {
 	struct clusterip_net *cn = clusterip_pernet(net);
-	int ret;
 
 	INIT_LIST_HEAD(&cn->configs);
 
 	spin_lock_init(&cn->lock);
 
-	ret = nf_register_net_hook(net, &cip_arp_ops);
-	if (ret < 0)
-		return ret;
-
 #ifdef CONFIG_PROC_FS
 	cn->procdir = proc_mkdir("ipt_CLUSTERIP", net->proc_net);
 	if (!cn->procdir) {
-		nf_unregister_net_hook(net, &cip_arp_ops);
 		pr_err("Unable to proc dir entry\n");
 		return -ENOMEM;
 	}
@@ -850,7 +868,6 @@ static void clusterip_net_exit(struct net *net)
 	cn->procdir = NULL;
 	mutex_unlock(&cn->mutex);
 #endif
-	nf_unregister_net_hook(net, &cip_arp_ops);
 }
 
 static struct pernet_operations clusterip_net_ops = {
-- 
2.31.1

[PATCH nf-next 2/3] netfilter: ipt_CLUSTERIP: use clusterip_net to store pernet warning

[Florian Westphal]

No need to use struct net for this.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/ipv4/netfilter/ipt_CLUSTERIP.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c
index 11bcf599358d..e6f65885d12b 100644
--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
+++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
@@ -66,6 +66,7 @@ struct clusterip_net {
 	/* lock protects the configs list */
 	spinlock_t lock;
 
+	bool clusterip_deprecated_warning;
 #ifdef CONFIG_PROC_FS
 	struct proc_dir_entry *procdir;
 	/* mutex protects the config->pde*/
@@ -544,10 +545,10 @@ static int clusterip_tg_check(const struct xt_tgchk_param *par)
 
 	cn->hook_users++;
 
-	if (!par->net->xt.clusterip_deprecated_warning) {
+	if (!cn->clusterip_deprecated_warning) {
 		pr_info("ipt_CLUSTERIP is deprecated and it will removed soon, "
 			"use xt_cluster instead\n");
-		par->net->xt.clusterip_deprecated_warning = true;
+		cn->clusterip_deprecated_warning = true;
 	}
 
 	cipinfo->config = config;
-- 
2.31.1

[PATCH nf-next 3/3] netfilter: remove xt pernet data

[Florian Westphal]

clusterip is now handled via net_generic.

NOTRACK is tiny compared to rest of xt_CT feature set, even the existing
deprecation warning is bigger than the actual functionality.

Just remove the warning, its not worth keeping/adding a net_generic one.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 include/net/net_namespace.h  |  2 --
 include/net/netns/x_tables.h | 12 ------------
 net/netfilter/xt_CT.c        | 11 -----------
 3 files changed, 25 deletions(-)
 delete mode 100644 include/net/netns/x_tables.h

diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 12cf6d7ea62c..60693fd5de45 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -23,7 +23,6 @@
 #include <net/netns/ieee802154_6lowpan.h>
 #include <net/netns/sctp.h>
 #include <net/netns/netfilter.h>
-#include <net/netns/x_tables.h>
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 #include <net/netns/conntrack.h>
 #endif
@@ -132,7 +131,6 @@ struct net {
 #endif
 #ifdef CONFIG_NETFILTER
 	struct netns_nf		nf;
-	struct netns_xt		xt;
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 	struct netns_ct		ct;
 #endif
diff --git a/include/net/netns/x_tables.h b/include/net/netns/x_tables.h
deleted file mode 100644
index d02316ec2906..000000000000
--- a/include/net/netns/x_tables.h
+++ /dev/null
@@ -1,12 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef __NETNS_X_TABLES_H
-#define __NETNS_X_TABLES_H
-
-#include <linux/list.h>
-#include <linux/netfilter_defs.h>
-
-struct netns_xt {
-	bool notrack_deprecated_warning;
-	bool clusterip_deprecated_warning;
-};
-#endif
diff --git a/net/netfilter/xt_CT.c b/net/netfilter/xt_CT.c
index 12404d221026..0a913ce07425 100644
--- a/net/netfilter/xt_CT.c
+++ b/net/netfilter/xt_CT.c
@@ -351,21 +351,10 @@ notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
 	return XT_CONTINUE;
 }
 
-static int notrack_chk(const struct xt_tgchk_param *par)
-{
-	if (!par->net->xt.notrack_deprecated_warning) {
-		pr_info("netfilter: NOTRACK target is deprecated, "
-			"use CT instead or upgrade iptables\n");
-		par->net->xt.notrack_deprecated_warning = true;
-	}
-	return 0;
-}
-
 static struct xt_target notrack_tg_reg __read_mostly = {
 	.name		= "NOTRACK",
 	.revision	= 0,
 	.family		= NFPROTO_UNSPEC,
-	.checkentry	= notrack_chk,
 	.target		= notrack_tg,
 	.table		= "raw",
 	.me		= THIS_MODULE,
-- 
2.31.1

Re: [PATCH nf-next 0/3] netfilter: clusterip: don't register hook in all netns

[Pablo Neira Ayuso]

On Thu, Jul 22, 2021 at 10:48:31AM +0200, Florian Westphal wrote:
> This series stops ipt_CLUSTERIP from registering arp mangling hook
> unconditionally.
> 
> Hook gets installed/removed from checkentry/destroy callbacks.
> 
> Before this, modprobe ipt_CLUSTERIP would add a hook in each netns.
> While at it, also get rid of x_tables.h/xt storage space in struct net,
> there is no need for this.

Series applied, thanks.

I made a small update to 2/3 here:

@@ -517,6 +531,19 @@ static int clusterip_tg_check(const struct xt_tgchk_param *par)
                return ret;
        }

+       if (cn->hook_users == 0) {
+               ret = nf_register_net_hook(par->net, &cip_arp_ops);
+
+               if (ret < 0) {
+                       clusterip_config_entry_put(config); <--
+                       clusterip_config_put(config); <--

to use config instead cipinfo->config which is set on later.