kern/127042: [PATCH] pf recursion panic if interface group is the same as the new interface name

[Artis Caune]

>Number:         127042
>Category:       kern
>Synopsis:       [PATCH] pf recursion panic if interface group is the same as the new interface name
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Sep 02 11:10:01 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     Artis Caune
>Release:        7.0
>Organization:
>Environment:
>Description:
On carp enabled kernels, there is interface group "carp" with all carpX interfaces as menbers.
If I change name for any carpX interface to "carp", pf will panic with recursive call to pfi_kif_update().




#487 0xffffffff801d92dc in pfi_kif_update (kif=0xffffff0001ec4700) at /usr/src/sys/contrib/pf/net/pf_if.c:525
#488 0xffffffff801d92dc in pfi_kif_update (kif=0xffffff0001ec4700) at /usr/src/sys/contrib/pf/net/pf_if.c:525
#489 0xffffffff801d92dc in pfi_kif_update (kif=0xffffff0001ec4700) at /usr/src/sys/contrib/pf/net/pf_if.c:525
#490 0xffffffff801d92dc in pfi_kif_update (kif=0xffffff0001ec4700) at /usr/src/sys/contrib/pf/net/pf_if.c:525
#491 0xffffffff801d92dc in pfi_kif_update (kif=0xffffff0001ec4700) at /usr/src/sys/contrib/pf/net/pf_if.c:525
#492 0xffffffff801d9c0d in pfi_attach_ifnet_event (arg=Variable "arg" is not available.
) at /usr/src/sys/contrib/pf/net/pf_if.c:895
#493 0xffffffff8053f9f0 in ifhwioctl (cmd=Variable "cmd" is not available.
) at pcpu.h:194
#494 0xffffffff80541871 in if_detach (ifp=0xffffff0001f0d800) at /usr/src/sys/net/if.c:730
#495 0xffffffff804e11f2 in kern_ioctl (td=0xffffff00030e09f0, fd=3, com=2149607720, data=0xffffff0001ea28e0 "carp0") at file.h:266
#496 0xffffffff804e1519 in ioctl (td=0xffffff00030e09f0, uap=0xffffffffafaf7be0) at /usr/src/sys/kern/sys_generic.c:570
#497 0xffffffff80730514 in syscall (frame=0xffffffffafaf7c70) at /usr/src/sys/amd64/amd64/trap.c:841
#498 0xffffffff8071614b in Xpage () at /usr/src/sys/amd64/amd64/exception.S:228
#499 0x0000000800722cfc in ?? ()

>How-To-Repeat:
# ifconfig em0 group externals
# ifconfig em0 name externals

or

# ifconfig carp0 create
# ifconfig carp0 name carp


but the following works fine:

# ifconfig em0 group externals
# ifconfig fxp0 name externals

>Fix:
this patch will check:
*) if group name already exists when renaming interface
*) if interface already exists when adding interface to group


Patch attached with submission follows:

Index: sys/net/if.c
===================================================================
--- sys/net/if.c	(revision 182679)
+++ sys/net/if.c	(working copy)
@@ -828,6 +828,9 @@
 	    groupname[strlen(groupname) - 1] <= '9')
 		return (EINVAL);
 
+	if (ifunit(groupname) != NULL)
+		return (EEXIST);
+
 	IFNET_WLOCK();
 	TAILQ_FOREACH(ifgl, &ifp->if_groups, ifgl_next)
 		if (!strcmp(ifgl->ifgl_group->ifg_group, groupname)) {
@@ -1560,6 +1563,7 @@
 	char new_name[IFNAMSIZ];
 	struct ifaddr *ifa;
 	struct sockaddr_dl *sdl;
+	struct ifg_group *ifg = NULL;
 
 	ifr = (struct ifreq *)data;
 	switch (cmd) {
@@ -1671,6 +1675,14 @@
 			return (EINVAL);
 		if (ifunit(new_name) != NULL)
 			return (EEXIST);
+
+		IFNET_RLOCK();
+		TAILQ_FOREACH(ifg, &V_ifg_head, ifg_next)
+			if (!strcmp(ifg->ifg_group, groupname))
+				IFNET_RUNLOCK();
+				return (EEXIST);
+			}
+		IFNET_RUNLOCK();
 		
 		/* Announce the departure of the interface. */
 		rt_ifannouncemsg(ifp, IFAN_DEPARTURE);


>Release-Note:
>Audit-Trail:
>Unformatted: