[PATCH v2 net 3/5] ipv6: icmp: remove obsolete code in icmpv6_xrlim_allow()
From: Eric Dumazet <edumazet@google.com>
Date: 2026-02-16 14:28:43
Subsystem:
documentation, networking [general], networking [ipv4/ipv6], the rest · Maintainers:
Jonathan Corbet, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
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>
---
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 28c7e4f5ecf9e6b7519659e4e3eee7da508ded29..6921d8594b8493a25d62ffd586d0b9f6527409cb 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst@@ -3234,12 +3234,13 @@ 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 31ba677d0442a861fc87e163b43a0aa1df88d8d4..69be0a67a14009771b8662328fff9de7bb98101b 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c@@ -952,7 +952,7 @@ 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 375ecd779fda5e323841c3d664ded6aadd653dfd..0f41ca6f3d83e86ce97ce5a30613f58f4dc22dad 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); }
--
2.53.0.310.g728cabbaf7-goog