d/freebsd-nq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

New sysctl: net.inet.icmp.error_keeptags

Browse Source 
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
MFC after:	1 month
This commit is contained in:
Eugene Grosbein 2018-10-21 21:29:19 +00:00
parent a00d561893
commit 410634efd1
1 changed files with 10 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
sys/netinet/ip_icmp.c
View File

@ -158,6 +158,12 @@ SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_RW,
&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(oip->ip_len) -
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: