Date: Sun, 21 Oct 2018 21:29:20 +0000 (UTC) From: Eugene Grosbein <eugen@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r339558 - head/sys/netinet Message-ID: <201810212129.w9LLTKRl085976@repo.freebsd.org>
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Author: eugen Date: Sun Oct 21 21:29:19 2018 New Revision: 339558 URL: https://svnweb.freebsd.org/changeset/base/339558 Log: 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 MFC after: 1 month Modified: head/sys/netinet/ip_icmp.c Modified: head/sys/netinet/ip_icmp.c ============================================================================== --- head/sys/netinet/ip_icmp.c Sun Oct 21 21:17:42 2018 (r339557) +++ head/sys/netinet/ip_icmp.c Sun Oct 21 21:29:19 2018 (r339558) @@ -158,6 +158,12 @@ 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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