From f38474237516b14d37a69642de245c3c6d9cb004 Mon Sep 17 00:00:00 2001
From: James Tucker <james@tailscale.com>
Date: Tue, 2 Apr 2024 11:04:12 -0700
Subject: [PATCH] net/packet: allow more ICMP errors

We now allow some more ICMP errors to flow, specifically:

- ICMP parameter problem in both IPv4 and IPv6 (corrupt headers)
- ICMP Packet Too Big (for IPv6 PMTU)

Updates #311
Updates #8102
Updates #11002

Signed-off-by: James Tucker <james@tailscale.com>
---
 net/packet/icmp4.go  | 3 +++
 net/packet/icmp6.go  | 6 ++++++
 net/packet/packet.go | 4 ++--
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/net/packet/icmp4.go b/net/packet/icmp4.go
index 730239abf..06780e0bb 100644
--- a/net/packet/icmp4.go
+++ b/net/packet/icmp4.go
@@ -23,6 +23,7 @@
 	ICMP4EchoRequest  ICMP4Type = 0x08
 	ICMP4Unreachable  ICMP4Type = 0x03
 	ICMP4TimeExceeded ICMP4Type = 0x0b
+	ICMP4ParamProblem ICMP4Type = 0x12
 )
 
 func (t ICMP4Type) String() string {
@@ -35,6 +36,8 @@ func (t ICMP4Type) String() string {
 		return "Unreachable"
 	case ICMP4TimeExceeded:
 		return "TimeExceeded"
+	case ICMP4ParamProblem:
+		return "ParamProblem"
 	default:
 		return "Unknown"
 	}
diff --git a/net/packet/icmp6.go b/net/packet/icmp6.go
index 518746b55..f78db1f4a 100644
--- a/net/packet/icmp6.go
+++ b/net/packet/icmp6.go
@@ -20,7 +20,9 @@
 
 const (
 	ICMP6Unreachable  ICMP6Type = 1
+	ICMP6PacketTooBig ICMP6Type = 2
 	ICMP6TimeExceeded ICMP6Type = 3
+	ICMP6ParamProblem ICMP6Type = 4
 	ICMP6EchoRequest  ICMP6Type = 128
 	ICMP6EchoReply    ICMP6Type = 129
 )
@@ -29,8 +31,12 @@ func (t ICMP6Type) String() string {
 	switch t {
 	case ICMP6Unreachable:
 		return "Unreachable"
+	case ICMP6PacketTooBig:
+		return "PacketTooBig"
 	case ICMP6TimeExceeded:
 		return "TimeExceeded"
+	case ICMP6ParamProblem:
+		return "ParamProblem"
 	case ICMP6EchoRequest:
 		return "EchoRequest"
 	case ICMP6EchoReply:
diff --git a/net/packet/packet.go b/net/packet/packet.go
index 9e837e575..dc870414a 100644
--- a/net/packet/packet.go
+++ b/net/packet/packet.go
@@ -416,13 +416,13 @@ func (q *Parsed) IsError() bool {
 			return false
 		}
 		t := ICMP4Type(q.b[q.subofs])
-		return t == ICMP4Unreachable || t == ICMP4TimeExceeded
+		return t == ICMP4Unreachable || t == ICMP4TimeExceeded || t == ICMP4ParamProblem
 	case ipproto.ICMPv6:
 		if len(q.b) < q.subofs+8 {
 			return false
 		}
 		t := ICMP6Type(q.b[q.subofs])
-		return t == ICMP6Unreachable || t == ICMP6TimeExceeded
+		return t == ICMP6Unreachable || t == ICMP6PacketTooBig || t == ICMP6TimeExceeded || t == ICMP6ParamProblem
 	default:
 		return false
 	}