Date: Fri, 19 Jul 2002 16:21:08 +0800 (KRAST) From: Eugene Grosbein <eugen@grosbein.pp.ru> To: FreeBSD-gnats-submit@FreeBSD.org Subject: kern/40763: [UPDATED PATCH] Introduction of non-strict IFF_NOARP semantics Message-ID: <200207190821.g6J8L85h014989@gw2b.svzserv.kemerovo.su>
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>Number: 40763
>Category: kern
>Synopsis: [UPDATED PATCH] Introduction of non-strict IFF_NOARP semantics
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Fri Jul 19 02:30:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: Eugene Grosbein
>Release: FreeBSD 4.6-STABLE i386
>Organization:
Svyaz Service JSC
>Environment:
System: FreeBSD gw2b.svzserv.kemerovo.su 4.6-STABLE FreeBSD 4.6-STABLE #2: Tue Jul 16 12:08:52 KRAST 2002 sa@gw2b.svzserv.kemerovo.su:/usr/obj/usr/src/sys/GW2 i386
>Description:
This PR obsoletes kern/36373 providing patch for 4.6-STABLE.
FreeBSD currently handles flag NOARP for network interface
in the way that completely disables ARP for that interface.
It's often too strict for real world operations. Sometimes
we just want ARP table to be protected from modification
via public interface but gateway must respond to ARP queries
for its own MAC address. So, this host can cooperate with
known hosts only (using preloaded ARP table) and can act as gateway
for them and those hosts are not forced to have static ARP
records themselves. The patches implementing such behavour
float around for long time. Here is an adaptaion of one such patch
for 4.6-STABLE. It introduces new sysctl named
net.link.ether.inet.strict_noarp with default value of 1.
This value corresponds to current meaning of IFF_NOARP.
One can change it to 0 to enable host to reply to ARP queries;
the ARP table is still protected from modifications
via interfaces marked as NOARP.
>How-To-Repeat:
There is no problem, see above.
>Fix:
Apply this patch.
Index: sys/net/if_ethersubr.c
===================================================================
RCS file: /home/ncvs/src/sys/net/if_ethersubr.c,v
retrieving revision 1.70.2.27
diff -u -r1.70.2.27 if_ethersubr.c
--- sys/net/if_ethersubr.c 9 Jul 2002 09:11:41 -0000 1.70.2.27
+++ sys/net/if_ethersubr.c 19 Jul 2002 05:59:50 -0000
@@ -99,6 +99,10 @@
extern u_char aarp_org_code[3];
#endif /* NETATALK */
+#ifdef INET
+extern int strict_noarp; /* defined in src/netinet/if_ether.c */
+#endif
+
/* netgraph node hooks for ng_ether(4) */
void (*ng_ether_input_p)(struct ifnet *ifp,
struct mbuf **mp, struct ether_header *eh);
@@ -691,11 +695,12 @@
break;
case ETHERTYPE_ARP:
- if (ifp->if_flags & IFF_NOARP) {
+ if (strict_noarp && (ifp->if_flags & IFF_NOARP)) {
/* Discard packet if ARP is disabled on interface */
m_freem(m);
return;
}
+
schednetisr(NETISR_ARP);
inq = &arpintrq;
break;
Index: sys/netinet/if_ether.c
===================================================================
RCS file: /home/ncvs/src/sys/netinet/if_ether.c,v
retrieving revision 1.64.2.19
diff -u -r1.64.2.19 if_ether.c
--- sys/netinet/if_ether.c 18 Jun 2002 00:15:31 -0000 1.64.2.19
+++ sys/netinet/if_ether.c 19 Jul 2002 05:59:50 -0000
@@ -107,6 +107,7 @@
static int arp_maxtries = 5;
static int useloopback = 1; /* use loopback interface for local traffic */
static int arp_proxyall = 0;
+int strict_noarp = 1; /* used in src/net/if_ethersubr.c */
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
&arp_maxtries, 0, "");
@@ -114,6 +115,8 @@
&useloopback, 0, "");
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
&arp_proxyall, 0, "");
+SYSCTL_INT(_net_link_ether_inet, OID_AUTO, strict_noarp, CTLFLAG_RW,
+ &strict_noarp, 0, "");
static void arp_rtrequest __P((int, struct rtentry *, struct rt_addrinfo *));
static void arprequest __P((struct ifnet *,
@@ -456,7 +459,7 @@
* Probably should not allocate empty llinfo struct if we are
* not going to be sending out an arp request.
*/
- if (ifp->if_flags & IFF_NOARP) {
+ if (strict_noarp && (ifp->if_flags & IFF_NOARP)) {
m_freem(m);
return (0);
}
@@ -651,6 +654,7 @@
itaddr = myaddr;
goto reply;
}
+ if (strict_noarp || !(ifp->if_flags & IFF_NOARP)) {
la = arplookup(isaddr.s_addr, itaddr.s_addr == myaddr.s_addr, 0);
if (la && (rt = la->la_rt) && (sdl = SDL(rt->rt_gateway))) {
/* the following is not an error when doing bridging */
@@ -740,6 +744,7 @@
rt_key(rt), rt);
la->la_hold = 0;
}
+ }
}
reply:
if (op != ARPOP_REQUEST) {
Eugene Grosbein
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