From: David Howells <dhowells@redhat.com>
Date: Wed, 12 Feb 2025 11:21:24 +0000 (+0000)
Subject: rxrpc: Fix ipv6 path MTU discovery
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=540cda75884a6ba4c289980c84392261b1f61a9c;p=users%2Fwilly%2Fpagecache.git

rxrpc: Fix ipv6 path MTU discovery

rxrpc path MTU discovery currently only makes use of ICMPv4, but not
ICMPv6, which means that pmtud for IPv6 doesn't work correctly.  Fix it to
check for ICMPv6 messages also.

Fixes: eeaedc5449d9 ("rxrpc: Implement path-MTU probing using padded PING ACKs (RFC8899)")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Simon Horman <horms@kernel.org>
cc: linux-afs@lists.infradead.org
Link: https://patch.msgid.link/3517283.1739359284@warthog.procyon.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/net/rxrpc/peer_event.c b/net/rxrpc/peer_event.c
index e874c31fa9012..bc283da9ee402 100644
--- a/net/rxrpc/peer_event.c
+++ b/net/rxrpc/peer_event.c
@@ -169,6 +169,13 @@ void rxrpc_input_error(struct rxrpc_local *local, struct sk_buff *skb)
 		goto out;
 	}
 
+	if ((serr->ee.ee_origin == SO_EE_ORIGIN_ICMP6 &&
+	     serr->ee.ee_type == ICMPV6_PKT_TOOBIG &&
+	     serr->ee.ee_code == 0)) {
+		rxrpc_adjust_mtu(peer, serr->ee.ee_info);
+		goto out;
+	}
+
 	rxrpc_store_error(peer, skb);
 out:
 	rxrpc_put_peer(peer, rxrpc_peer_put_input_error);