From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Eric Dumazet <edumazet@google.com>,
	Kuniyuki Iwashima <kuniyu@google.com>,
	Martin KaFai Lau <martin.lau@kernel.org>,
	Jakub Kicinski <kuba@kernel.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.18 554/641] ipv6: icmp: remove obsolete code in icmpv6_xrlim_allow()
Date: Tue, 24 Feb 2026 17:24:40 -0800
Message-ID: <20260225012401.949141328@linuxfoundation.org>
In-Reply-To: <20260225012348.915798704@linuxfoundation.org>
References: <20260225012348.915798704@linuxfoundation.org>
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6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 0201eedb69b24a6be9b7c1716287a89c4dde2320 ]

Following part was needed before the blamed commit, because
inet_getpeer_v6() second argument was the prefix.

	/* Give more bandwidth to wider prefixes. */
	if (rt->rt6i_dst.plen < 128)
		tmo >>= ((128 - rt->rt6i_dst.plen)>>5);

Now inet_getpeer_v6() retrieves hosts, we need to remove
@tmo adjustement or wider prefixes likes /24 allow 8x
more ICMP to be sent for a given ratelimit.

As we had this issue for a while, this patch changes net.ipv6.icmp.ratelimit
default value from 1000ms to 100ms to avoid potential regressions.

Also add a READ_ONCE() when reading net->ipv6.sysctl.icmpv6_time.

Fixes: fd0273d7939f ("ipv6: Remove external dependency on rt6i_dst and rt6i_src")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Cc: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20260216142832.3834174-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 Documentation/networking/ip-sysctl.rst | 7 ++++---
 net/ipv6/af_inet6.c                    | 2 +-
 net/ipv6/icmp.c                        | 7 +------
 3 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index a06cb99d66dcd..7a637e87005fe 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -3195,12 +3195,13 @@ enhanced_dad - BOOLEAN
 ===========
 
 ratelimit - INTEGER
-	Limit the maximal rates for sending ICMPv6 messages.
+	Limit the maximal rates for sending ICMPv6 messages to a particular
+	peer.
 
 	0 to disable any limiting,
-	otherwise the minimal space between responses in milliseconds.
+	otherwise the space between responses in milliseconds.
 
-	Default: 1000
+	Default: 100
 
 ratemask - list of comma separated ranges
 	For ICMPv6 message types matching the ranges in the ratemask, limit
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 1b0314644e0cc..0e8f48835869c 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -955,7 +955,7 @@ static int __net_init inet6_net_init(struct net *net)
 	int err = 0;
 
 	net->ipv6.sysctl.bindv6only = 0;
-	net->ipv6.sysctl.icmpv6_time = 1*HZ;
+	net->ipv6.sysctl.icmpv6_time = HZ / 10;
 	net->ipv6.sysctl.icmpv6_echo_ignore_all = 0;
 	net->ipv6.sysctl.icmpv6_echo_ignore_multicast = 0;
 	net->ipv6.sysctl.icmpv6_echo_ignore_anycast = 0;
diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index 306eec18e82c1..35b32dcf581ff 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -217,14 +217,9 @@ static bool icmpv6_xrlim_allow(struct sock *sk, u8 type,
 	} else if (dev && (dev->flags & IFF_LOOPBACK)) {
 		res = true;
 	} else {
-		struct rt6_info *rt = dst_rt6_info(dst);
-		int tmo = net->ipv6.sysctl.icmpv6_time;
+		int tmo = READ_ONCE(net->ipv6.sysctl.icmpv6_time);
 		struct inet_peer *peer;
 
-		/* Give more bandwidth to wider prefixes. */
-		if (rt->rt6i_dst.plen < 128)
-			tmo >>= ((128 - rt->rt6i_dst.plen)>>5);
-
 		peer = inet_getpeer_v6(net->ipv6.peers, &fl6->daddr);
 		res = inet_peer_xrlim_allow(peer, tmo);
 	}
-- 
2.51.0