Author: eugen
Date: Tue Nov 20 10:44:49 2018
New Revision: 340670
URL: https://svnweb.freebsd.org/changeset/base/340670
Log:
MFC r339558: New sysctl: net.inet.icmp.error_keeptags
Currently, icmp_error() function copies FIB number from original packet
into generated ICMP response but not mbuf_tags(9) chain.
This prevents us from easily matching ICMP responses corresponding
to tagged original packets by means of packet filter such as ipfw(8).
For example, ICMP "time-exceeded in-transit" packets usually generated
in response to traceroute probes lose tags attached to original packets.
This change adds new sysctl net.inet.icmp.error_keeptags
that defaults to 0 to avoid extra overhead when this feature not needed.
Set net.inet.icmp.error_keeptags=1 to make icmp_error() copy mbuf_tags
from original packet to generated ICMP response.
PR: 215874
Modified:
stable/11/sys/netinet/ip_icmp.c
Directory Properties:
stable/11/ (props changed)
Modified: stable/11/sys/netinet/ip_icmp.c
==============================================================================
--- stable/11/sys/netinet/ip_icmp.c Tue Nov 20 10:43:18 2018
(r340669)
+++ stable/11/sys/netinet/ip_icmp.c Tue Nov 20 10:44:49 2018
(r340670)
@@ -155,6 +155,12 @@ SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFL
&VNET_NAME(icmptstamprepl), 0,
"Respond to ICMP Timestamp packets");
+VNET_DEFINE_STATIC(int, error_keeptags) = 0;
+#define V_error_keeptags VNET(error_keeptags)
+SYSCTL_INT(_net_inet_icmp, OID_AUTO, error_keeptags, CTLFLAG_VNET | CTLFLAG_RW,
+ &VNET_NAME(error_keeptags), 0,
+ "ICMP error response keeps copy of mbuf_tags of original packet");
+
#ifdef ICMPPRINTFS
int icmpprintfs = 0;
#endif
@@ -367,6 +373,10 @@ stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs
nip->ip_p = IPPROTO_ICMP;
nip->ip_tos = 0;
nip->ip_off = 0;
+
+ if (V_error_keeptags)
+ m_tag_copy_chain(m, n, M_NOWAIT);
+
icmp_reflect(m);
freeit:
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