[PATCH net-next 0/5] netfilter: updates for net-next

[PATCH net-next 0/5] netfilter: updates for net-next

[Florian Westphal]

The following patchset contains Netfilter changes for *net-next*:

1) Don't respond to ICMP_UNREACH errors with another ICMP_UNREACH
   error.
2) Support fetching the current bridge ethernet address.
   This allows a more flexible approach to packet redirection
   on bridges without need to use hardcoded addresses. From
   Fernando Fernandez Mancera.
3) Zap a few no-longer needed conditionals from ipvs packet path
   and convert to READ/WRITE_ONCE to avoid KCSAN warnings.
   From Zhang Tengfei.
4) Remove a no-longer-used macro argument in ipset, from Zhen Ni.

Please, pull these changes from:
The following changes since commit 5adf6f2b9972dbb69f4dd11bae52ba251c64ecb7:

  Merge branch 'ipv4-icmp-fix-source-ip-derivation-in-presence-of-vrfs' (2025-09-11 12:22:40 +0200)

are available in the Git repository at:

  https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next.git tags/nf-next-25-09-11

for you to fetch changes up to db99b2f2b3e2cd8227ac9990ca4a8a31a1e95e56:

  netfilter: nf_reject: don't reply to icmp error messages (2025-09-11 15:40:55 +0200)

----------------------------------------------------------------
netfilter pull request nf-next-25-09-11

----------------------------------------------------------------
Andres Urian Florez (1):
      selftest:net: fixed spelling mistakes

Fernando Fernandez Mancera (1):
      netfilter: nft_meta_bridge: introduce NFT_META_BRI_IIFHWADDR support

Florian Westphal (1):
      netfilter: nf_reject: don't reply to icmp error messages

Zhang Tengfei (1):
      ipvs: Use READ_ONCE/WRITE_ONCE for ipvs->enable

Zhen Ni (1):
      netfilter: ipset: Remove unused htable_bits in macro ahash_region

 include/uapi/linux/netfilter/nf_tables.h         |  2 ++
 net/bridge/netfilter/nft_meta_bridge.c           | 11 +++++++++
 net/ipv4/netfilter/nf_reject_ipv4.c              | 25 ++++++++++++++++++++
 net/ipv6/netfilter/nf_reject_ipv6.c              | 30 ++++++++++++++++++++++++
 net/netfilter/ipset/ip_set_hash_gen.h            |  8 +++----
 net/netfilter/ipvs/ip_vs_conn.c                  |  4 ++--
 net/netfilter/ipvs/ip_vs_core.c                  | 11 ++++-----
 net/netfilter/ipvs/ip_vs_ctl.c                   |  6 ++---
 net/netfilter/ipvs/ip_vs_est.c                   | 16 ++++++-------
 tools/testing/selftests/net/netfilter/nft_nat.sh |  4 ++--
 10 files changed, 91 insertions(+), 26 deletions(-)

[PATCH net-next 1/5] selftest:net: fixed spelling mistakes

[Florian Westphal]

From: Andres Urian Florez <andres.emb.sys@gmail.com>

Fixed spelling errors in test_redirect6() error message and
test_port_shadowing() comments

Signed-off-by: Andres Urian Florez <andres.emb.sys@gmail.com>
Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 tools/testing/selftests/net/netfilter/nft_nat.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/net/netfilter/nft_nat.sh b/tools/testing/selftests/net/netfilter/nft_nat.sh
index a954754b99b3..b3ec2d0a3f56 100755
--- a/tools/testing/selftests/net/netfilter/nft_nat.sh
+++ b/tools/testing/selftests/net/netfilter/nft_nat.sh
@@ -569,7 +569,7 @@ test_redirect6()
 	ip netns exec "$ns0" sysctl net.ipv6.conf.all.forwarding=1 > /dev/null
 
 	if ! ip netns exec "$ns2" ping -q -c 1 dead:1::99 > /dev/null;then
-		echo "ERROR: cannnot ping $ns1 from $ns2 via ipv6"
+		echo "ERROR: cannot ping $ns1 from $ns2 via ipv6"
 		lret=1
 	fi
 
@@ -859,7 +859,7 @@ EOF
 	# from router:service bypass connection tracking.
 	test_port_shadow_notrack "$family"
 
-	# test nat based mitigation: fowarded packets coming from service port
+	# test nat based mitigation: forwarded packets coming from service port
 	# are masqueraded with random highport.
 	test_port_shadow_pat "$family"
 
-- 
2.49.1

Re: [PATCH net-next 1/5] selftest:net: fixed spelling mistakes

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Florian Westphal <fw@strlen.de>:

On Thu, 11 Sep 2025 16:38:15 +0200 you wrote:
> From: Andres Urian Florez <andres.emb.sys@gmail.com>
> 
> Fixed spelling errors in test_redirect6() error message and
> test_port_shadowing() comments
> 
> Signed-off-by: Andres Urian Florez <andres.emb.sys@gmail.com>
> Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>
> Signed-off-by: Florian Westphal <fw@strlen.de>
> 
> [...]

Here is the summary with links:
  - [net-next,1/5] selftest:net: fixed spelling mistakes
    https://git.kernel.org/netdev/net-next/c/496a6ed8405e
  - [net-next,2/5] netfilter: ipset: Remove unused htable_bits in macro ahash_region
    https://git.kernel.org/netdev/net-next/c/ba941796d7cd
  - [net-next,3/5] netfilter: nft_meta_bridge: introduce NFT_META_BRI_IIFHWADDR support
    https://git.kernel.org/netdev/net-next/c/cbd2257dc96e
  - [net-next,4/5] ipvs: Use READ_ONCE/WRITE_ONCE for ipvs->enable
    https://git.kernel.org/netdev/net-next/c/944b6b216c03
  - [net-next,5/5] netfilter: nf_reject: don't reply to icmp error messages
    https://git.kernel.org/netdev/net-next/c/db99b2f2b3e2

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

[PATCH net-next 2/5] netfilter: ipset: Remove unused htable_bits in macro ahash_region

[Florian Westphal]

From: Zhen Ni <zhen.ni@easystack.cn>

Since the ahash_region() macro was redefined to calculate the region
index solely from HTABLE_REGION_BITS, the htable_bits parameter became
unused.

Remove the unused htable_bits argument and its call sites, simplifying
the code without changing semantics.

Fixes: 8478a729c046 ("netfilter: ipset: fix region locking in hash types")
Signed-off-by: Zhen Ni <zhen.ni@easystack.cn>
Reviewed-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/netfilter/ipset/ip_set_hash_gen.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/netfilter/ipset/ip_set_hash_gen.h b/net/netfilter/ipset/ip_set_hash_gen.h
index 5251524b96af..5e4453e9ef8e 100644
--- a/net/netfilter/ipset/ip_set_hash_gen.h
+++ b/net/netfilter/ipset/ip_set_hash_gen.h
@@ -63,7 +63,7 @@ struct hbucket {
 		: jhash_size((htable_bits) - HTABLE_REGION_BITS))
 #define ahash_sizeof_regions(htable_bits)		\
 	(ahash_numof_locks(htable_bits) * sizeof(struct ip_set_region))
-#define ahash_region(n, htable_bits)		\
+#define ahash_region(n)		\
 	((n) / jhash_size(HTABLE_REGION_BITS))
 #define ahash_bucket_start(h,  htable_bits)	\
 	((htable_bits) < HTABLE_REGION_BITS ? 0	\
@@ -702,7 +702,7 @@ mtype_resize(struct ip_set *set, bool retried)
 #endif
 				key = HKEY(data, h->initval, htable_bits);
 				m = __ipset_dereference(hbucket(t, key));
-				nr = ahash_region(key, htable_bits);
+				nr = ahash_region(key);
 				if (!m) {
 					m = kzalloc(sizeof(*m) +
 					    AHASH_INIT_SIZE * dsize,
@@ -852,7 +852,7 @@ mtype_add(struct ip_set *set, void *value, const struct ip_set_ext *ext,
 	rcu_read_lock_bh();
 	t = rcu_dereference_bh(h->table);
 	key = HKEY(value, h->initval, t->htable_bits);
-	r = ahash_region(key, t->htable_bits);
+	r = ahash_region(key);
 	atomic_inc(&t->uref);
 	elements = t->hregion[r].elements;
 	maxelem = t->maxelem;
@@ -1050,7 +1050,7 @@ mtype_del(struct ip_set *set, void *value, const struct ip_set_ext *ext,
 	rcu_read_lock_bh();
 	t = rcu_dereference_bh(h->table);
 	key = HKEY(value, h->initval, t->htable_bits);
-	r = ahash_region(key, t->htable_bits);
+	r = ahash_region(key);
 	atomic_inc(&t->uref);
 	rcu_read_unlock_bh();
 
-- 
2.49.1

[PATCH net-next 3/5] netfilter: nft_meta_bridge: introduce NFT_META_BRI_IIFHWADDR support

[Florian Westphal]

From: Fernando Fernandez Mancera <fmancera@suse.de>

Expose the input bridge interface ethernet address so it can be used to
redirect the packet to the receiving physical device for processing.

Tested with nft command line tool.

table bridge nat {
	chain PREROUTING {
		type filter hook prerouting priority 0; policy accept;
		ether daddr de:ad:00:00:be:ef meta pkttype set host ether daddr set meta ibrhwdr accept
	}
}

Joint work with Pablo Neira.

Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 include/uapi/linux/netfilter/nf_tables.h |  2 ++
 net/bridge/netfilter/nft_meta_bridge.c   | 11 +++++++++++
 2 files changed, 13 insertions(+)

diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index 8e0eb832bc01..7c0c915f0306 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -959,6 +959,7 @@ enum nft_exthdr_attributes {
  * @NFT_META_SDIF: slave device interface index
  * @NFT_META_SDIFNAME: slave device interface name
  * @NFT_META_BRI_BROUTE: packet br_netfilter_broute bit
+ * @NFT_META_BRI_IIFHWADDR: packet input bridge interface ethernet address
  */
 enum nft_meta_keys {
 	NFT_META_LEN,
@@ -999,6 +1000,7 @@ enum nft_meta_keys {
 	NFT_META_SDIFNAME,
 	NFT_META_BRI_BROUTE,
 	__NFT_META_IIFTYPE,
+	NFT_META_BRI_IIFHWADDR,
 };
 
 /**
diff --git a/net/bridge/netfilter/nft_meta_bridge.c b/net/bridge/netfilter/nft_meta_bridge.c
index 5adced1e7d0c..b7af36bbd306 100644
--- a/net/bridge/netfilter/nft_meta_bridge.c
+++ b/net/bridge/netfilter/nft_meta_bridge.c
@@ -59,6 +59,13 @@ static void nft_meta_bridge_get_eval(const struct nft_expr *expr,
 		nft_reg_store_be16(dest, htons(p_proto));
 		return;
 	}
+	case NFT_META_BRI_IIFHWADDR:
+		br_dev = nft_meta_get_bridge(in);
+		if (!br_dev)
+			goto err;
+
+		memcpy(dest, br_dev->dev_addr, ETH_ALEN);
+		return;
 	default:
 		return nft_meta_get_eval(expr, regs, pkt);
 	}
@@ -86,6 +93,9 @@ static int nft_meta_bridge_get_init(const struct nft_ctx *ctx,
 	case NFT_META_BRI_IIFVPROTO:
 		len = sizeof(u16);
 		break;
+	case NFT_META_BRI_IIFHWADDR:
+		len = ETH_ALEN;
+		break;
 	default:
 		return nft_meta_get_init(ctx, expr, tb);
 	}
@@ -175,6 +185,7 @@ static int nft_meta_bridge_set_validate(const struct nft_ctx *ctx,
 
 	switch (priv->key) {
 	case NFT_META_BRI_BROUTE:
+	case NFT_META_BRI_IIFHWADDR:
 		hooks = 1 << NF_BR_PRE_ROUTING;
 		break;
 	default:
-- 
2.49.1

[PATCH net-next 4/5] ipvs: Use READ_ONCE/WRITE_ONCE for ipvs->enable

[Florian Westphal]

From: Zhang Tengfei <zhtfdev@gmail.com>

KCSAN reported a data-race on the `ipvs->enable` flag, which is
written in the control path and read concurrently from many other
contexts.

Following a suggestion by Julian, this patch fixes the race by
converting all accesses to use `WRITE_ONCE()/READ_ONCE()`.
This lightweight approach ensures atomic access and acts as a
compiler barrier, preventing unsafe optimizations where the flag
is checked in loops (e.g., in ip_vs_est.c).

Additionally, the `enable` checks in the fast-path hooks
(`ip_vs_in_hook`, `ip_vs_out_hook`, `ip_vs_forward_icmp`) are
removed. These are unnecessary since commit 857ca89711de
("ipvs: register hooks only with services"). The `enable=0`
condition they check for can only occur in two rare and non-fatal
scenarios: 1) after hooks are registered but before the flag is set,
and 2) after hooks are unregistered on cleanup_net. In the worst
case, a single packet might be mishandled (e.g., dropped), which
does not lead to a system crash or data corruption. Adding a check
in the performance-critical fast-path to handle this harmless
condition is not a worthwhile trade-off.

Fixes: 857ca89711de ("ipvs: register hooks only with services")
Reported-by: syzbot+1651b5234028c294c339@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=1651b5234028c294c339
Suggested-by: Julian Anastasov <ja@ssi.bg>
Link: https://lore.kernel.org/lvs-devel/2189fc62-e51e-78c9-d1de-d35b8e3657e3@ssi.bg/
Signed-off-by: Zhang Tengfei <zhtfdev@gmail.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/netfilter/ipvs/ip_vs_conn.c |  4 ++--
 net/netfilter/ipvs/ip_vs_core.c | 11 ++++-------
 net/netfilter/ipvs/ip_vs_ctl.c  |  6 +++---
 net/netfilter/ipvs/ip_vs_est.c  | 16 ++++++++--------
 4 files changed, 17 insertions(+), 20 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
index 965f3c8e5089..37ebb0cb62b8 100644
--- a/net/netfilter/ipvs/ip_vs_conn.c
+++ b/net/netfilter/ipvs/ip_vs_conn.c
@@ -885,7 +885,7 @@ static void ip_vs_conn_expire(struct timer_list *t)
 			 * conntrack cleanup for the net.
 			 */
 			smp_rmb();
-			if (ipvs->enable)
+			if (READ_ONCE(ipvs->enable))
 				ip_vs_conn_drop_conntrack(cp);
 		}
 
@@ -1439,7 +1439,7 @@ void ip_vs_expire_nodest_conn_flush(struct netns_ipvs *ipvs)
 		cond_resched_rcu();
 
 		/* netns clean up started, abort delayed work */
-		if (!ipvs->enable)
+		if (!READ_ONCE(ipvs->enable))
 			break;
 	}
 	rcu_read_unlock();
diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
index c7a8a08b7308..5ea7ab8bf4dc 100644
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c
@@ -1353,9 +1353,6 @@ ip_vs_out_hook(void *priv, struct sk_buff *skb, const struct nf_hook_state *stat
 	if (unlikely(!skb_dst(skb)))
 		return NF_ACCEPT;
 
-	if (!ipvs->enable)
-		return NF_ACCEPT;
-
 	ip_vs_fill_iph_skb(af, skb, false, &iph);
 #ifdef CONFIG_IP_VS_IPV6
 	if (af == AF_INET6) {
@@ -1940,7 +1937,7 @@ ip_vs_in_hook(void *priv, struct sk_buff *skb, const struct nf_hook_state *state
 		return NF_ACCEPT;
 	}
 	/* ipvs enabled in this netns ? */
-	if (unlikely(sysctl_backup_only(ipvs) || !ipvs->enable))
+	if (unlikely(sysctl_backup_only(ipvs)))
 		return NF_ACCEPT;
 
 	ip_vs_fill_iph_skb(af, skb, false, &iph);
@@ -2108,7 +2105,7 @@ ip_vs_forward_icmp(void *priv, struct sk_buff *skb,
 	int r;
 
 	/* ipvs enabled in this netns ? */
-	if (unlikely(sysctl_backup_only(ipvs) || !ipvs->enable))
+	if (unlikely(sysctl_backup_only(ipvs)))
 		return NF_ACCEPT;
 
 	if (state->pf == NFPROTO_IPV4) {
@@ -2295,7 +2292,7 @@ static int __net_init __ip_vs_init(struct net *net)
 		return -ENOMEM;
 
 	/* Hold the beast until a service is registered */
-	ipvs->enable = 0;
+	WRITE_ONCE(ipvs->enable, 0);
 	ipvs->net = net;
 	/* Counters used for creating unique names */
 	ipvs->gen = atomic_read(&ipvs_netns_cnt);
@@ -2367,7 +2364,7 @@ static void __net_exit __ip_vs_dev_cleanup_batch(struct list_head *net_list)
 		ipvs = net_ipvs(net);
 		ip_vs_unregister_hooks(ipvs, AF_INET);
 		ip_vs_unregister_hooks(ipvs, AF_INET6);
-		ipvs->enable = 0;	/* Disable packet reception */
+		WRITE_ONCE(ipvs->enable, 0);	/* Disable packet reception */
 		smp_wmb();
 		ip_vs_sync_net_cleanup(ipvs);
 	}
diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index 6a6fc4478533..4c8fa22be88a 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -256,7 +256,7 @@ static void est_reload_work_handler(struct work_struct *work)
 		struct ip_vs_est_kt_data *kd = ipvs->est_kt_arr[id];
 
 		/* netns clean up started, abort delayed work */
-		if (!ipvs->enable)
+		if (!READ_ONCE(ipvs->enable))
 			goto unlock;
 		if (!kd)
 			continue;
@@ -1483,9 +1483,9 @@ ip_vs_add_service(struct netns_ipvs *ipvs, struct ip_vs_service_user_kern *u,
 
 	*svc_p = svc;
 
-	if (!ipvs->enable) {
+	if (!READ_ONCE(ipvs->enable)) {
 		/* Now there is a service - full throttle */
-		ipvs->enable = 1;
+		WRITE_ONCE(ipvs->enable, 1);
 
 		/* Start estimation for first time */
 		ip_vs_est_reload_start(ipvs);
diff --git a/net/netfilter/ipvs/ip_vs_est.c b/net/netfilter/ipvs/ip_vs_est.c
index 15049b826732..93a925f1ed9b 100644
--- a/net/netfilter/ipvs/ip_vs_est.c
+++ b/net/netfilter/ipvs/ip_vs_est.c
@@ -231,7 +231,7 @@ static int ip_vs_estimation_kthread(void *data)
 void ip_vs_est_reload_start(struct netns_ipvs *ipvs)
 {
 	/* Ignore reloads before first service is added */
-	if (!ipvs->enable)
+	if (!READ_ONCE(ipvs->enable))
 		return;
 	ip_vs_est_stopped_recalc(ipvs);
 	/* Bump the kthread configuration genid */
@@ -306,7 +306,7 @@ static int ip_vs_est_add_kthread(struct netns_ipvs *ipvs)
 	int i;
 
 	if ((unsigned long)ipvs->est_kt_count >= ipvs->est_max_threads &&
-	    ipvs->enable && ipvs->est_max_threads)
+	    READ_ONCE(ipvs->enable) && ipvs->est_max_threads)
 		return -EINVAL;
 
 	mutex_lock(&ipvs->est_mutex);
@@ -343,7 +343,7 @@ static int ip_vs_est_add_kthread(struct netns_ipvs *ipvs)
 	}
 
 	/* Start kthread tasks only when services are present */
-	if (ipvs->enable && !ip_vs_est_stopped(ipvs)) {
+	if (READ_ONCE(ipvs->enable) && !ip_vs_est_stopped(ipvs)) {
 		ret = ip_vs_est_kthread_start(ipvs, kd);
 		if (ret < 0)
 			goto out;
@@ -486,7 +486,7 @@ int ip_vs_start_estimator(struct netns_ipvs *ipvs, struct ip_vs_stats *stats)
 	struct ip_vs_estimator *est = &stats->est;
 	int ret;
 
-	if (!ipvs->est_max_threads && ipvs->enable)
+	if (!ipvs->est_max_threads && READ_ONCE(ipvs->enable))
 		ipvs->est_max_threads = ip_vs_est_max_threads(ipvs);
 
 	est->ktid = -1;
@@ -663,7 +663,7 @@ static int ip_vs_est_calc_limits(struct netns_ipvs *ipvs, int *chain_max)
 			/* Wait for cpufreq frequency transition */
 			wait_event_idle_timeout(wq, kthread_should_stop(),
 						HZ / 50);
-			if (!ipvs->enable || kthread_should_stop())
+			if (!READ_ONCE(ipvs->enable) || kthread_should_stop())
 				goto stop;
 		}
 
@@ -681,7 +681,7 @@ static int ip_vs_est_calc_limits(struct netns_ipvs *ipvs, int *chain_max)
 		rcu_read_unlock();
 		local_bh_enable();
 
-		if (!ipvs->enable || kthread_should_stop())
+		if (!READ_ONCE(ipvs->enable) || kthread_should_stop())
 			goto stop;
 		cond_resched();
 
@@ -757,7 +757,7 @@ static void ip_vs_est_calc_phase(struct netns_ipvs *ipvs)
 	mutex_lock(&ipvs->est_mutex);
 	for (id = 1; id < ipvs->est_kt_count; id++) {
 		/* netns clean up started, abort */
-		if (!ipvs->enable)
+		if (!READ_ONCE(ipvs->enable))
 			goto unlock2;
 		kd = ipvs->est_kt_arr[id];
 		if (!kd)
@@ -787,7 +787,7 @@ static void ip_vs_est_calc_phase(struct netns_ipvs *ipvs)
 	id = ipvs->est_kt_count;
 
 next_kt:
-	if (!ipvs->enable || kthread_should_stop())
+	if (!READ_ONCE(ipvs->enable) || kthread_should_stop())
 		goto unlock;
 	id--;
 	if (id < 0)
-- 
2.49.1

[PATCH net-next 5/5] netfilter: nf_reject: don't reply to icmp error messages

[Florian Westphal]

tcp reject code won't reply to a tcp reset.

But the icmp reject 'netdev' family versions will reply to icmp
dst-unreach errors, unlike icmp_send() and icmp6_send() which are used
by the inet family implementation (and internally by the REJECT target).

Check for the icmp(6) type and do not respond if its an unreachable error.

Without this, something like 'ip protocol icmp reject', when used
in a netdev chain attached to 'lo', cause a packet loop.

Same for two hosts that both use such a rule: each error packet
will be replied to.

Such situation persist until the (bogus) rule is amended to ratelimit or
checks the icmp type before the reject statement.

As the inet versions don't do this make the netdev ones follow along.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/ipv4/netfilter/nf_reject_ipv4.c | 25 ++++++++++++++++++++++++
 net/ipv6/netfilter/nf_reject_ipv6.c | 30 +++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c
index 05631abe3f0d..fae4aa4a5f09 100644
--- a/net/ipv4/netfilter/nf_reject_ipv4.c
+++ b/net/ipv4/netfilter/nf_reject_ipv4.c
@@ -80,6 +80,27 @@ struct sk_buff *nf_reject_skb_v4_tcp_reset(struct net *net,
 }
 EXPORT_SYMBOL_GPL(nf_reject_skb_v4_tcp_reset);
 
+static bool nf_skb_is_icmp_unreach(const struct sk_buff *skb)
+{
+	const struct iphdr *iph = ip_hdr(skb);
+	u8 *tp, _type;
+	int thoff;
+
+	if (iph->protocol != IPPROTO_ICMP)
+		return false;
+
+	thoff = skb_network_offset(skb) + sizeof(*iph);
+
+	tp = skb_header_pointer(skb,
+				thoff + offsetof(struct icmphdr, type),
+				sizeof(_type), &_type);
+
+	if (!tp)
+		return false;
+
+	return *tp == ICMP_DEST_UNREACH;
+}
+
 struct sk_buff *nf_reject_skb_v4_unreach(struct net *net,
 					 struct sk_buff *oldskb,
 					 const struct net_device *dev,
@@ -100,6 +121,10 @@ struct sk_buff *nf_reject_skb_v4_unreach(struct net *net,
 	if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET))
 		return NULL;
 
+	/* don't reply to ICMP_DEST_UNREACH with ICMP_DEST_UNREACH. */
+	if (nf_skb_is_icmp_unreach(oldskb))
+		return NULL;
+
 	/* RFC says return as much as we can without exceeding 576 bytes. */
 	len = min_t(unsigned int, 536, oldskb->len);
 
diff --git a/net/ipv6/netfilter/nf_reject_ipv6.c b/net/ipv6/netfilter/nf_reject_ipv6.c
index 6b022449f867..ef5b7e85cffa 100644
--- a/net/ipv6/netfilter/nf_reject_ipv6.c
+++ b/net/ipv6/netfilter/nf_reject_ipv6.c
@@ -104,6 +104,32 @@ struct sk_buff *nf_reject_skb_v6_tcp_reset(struct net *net,
 }
 EXPORT_SYMBOL_GPL(nf_reject_skb_v6_tcp_reset);
 
+static bool nf_skb_is_icmp6_unreach(const struct sk_buff *skb)
+{
+	const struct ipv6hdr *ip6h = ipv6_hdr(skb);
+	u8 proto = ip6h->nexthdr;
+	u8 _type, *tp;
+	int thoff;
+	__be16 fo;
+
+	thoff = ipv6_skip_exthdr(skb, ((u8 *)(ip6h + 1) - skb->data), &proto, &fo);
+
+	if (thoff < 0 || thoff >= skb->len || fo != 0)
+		return false;
+
+	if (proto != IPPROTO_ICMPV6)
+		return false;
+
+	tp = skb_header_pointer(skb,
+				thoff + offsetof(struct icmp6hdr, icmp6_type),
+				sizeof(_type), &_type);
+
+	if (!tp)
+		return false;
+
+	return *tp == ICMPV6_DEST_UNREACH;
+}
+
 struct sk_buff *nf_reject_skb_v6_unreach(struct net *net,
 					 struct sk_buff *oldskb,
 					 const struct net_device *dev,
@@ -117,6 +143,10 @@ struct sk_buff *nf_reject_skb_v6_unreach(struct net *net,
 	if (!nf_reject_ip6hdr_validate(oldskb))
 		return NULL;
 
+	/* Don't reply to ICMPV6_DEST_UNREACH with ICMPV6_DEST_UNREACH */
+	if (nf_skb_is_icmp6_unreach(oldskb))
+		return NULL;
+
 	/* Include "As much of invoking packet as possible without the ICMPv6
 	 * packet exceeding the minimum IPv6 MTU" in the ICMP payload.
 	 */
-- 
2.49.1