conf/63700: Double configuration of cloned_interfaces if network_interfaces=auto

[Yar Tikhiy]

>Number:         63700
>Category:       conf
>Synopsis:       Double configuration of cloned_interfaces if network_interfaces=auto
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Mar 03 09:30:16 PST 2004
>Closed-Date:
>Last-Modified:
>Originator:     Yar Tikhiy
>Release:        FreeBSD 5.2-CURRENT i386
>Organization:
Moscow State University
>Environment:

System: FreeBSD stylish.chem.msu.su 5.2-CURRENT FreeBSD 5.2-CURRENT #1: Wed Mar 3 17:07:22 MSK 2004 yar at stylish.chem.msu.su:/usr/obj/usr/src/sys/STYLISH i386

>Description:

	If the rc.conf(5) variable network_interfaces is set to "auto",
	its default value, interfaces listed in cloned_interfaces will
	be doubly configured and their post-configuration status will be
	displayed twice.

	That is because the rc function network.subr:list_net_interfaces()
	doesn't check if the interfaces listed in cloned_interfaces have
	already been created--the function just concatenates the value of
	cloned_interfaces to output from `ifconfig -l`, which may include
	the names of the cloned interfaces, too.

>How-To-Repeat:

	Leave out network_interfaces from rc.conf, thus depending on
	the rc system to figure out the list of existing interfaces.
	In addition, specify some interfaces to clone through
	cloned_interfaces.  Observe the results to doubly configure
	the latter interfaces in rc(8) output.

	For example:

%%% rc.conf snippet %%%

	### network_interfaces="lo0 fxp0"
	cloned_interfaces="vlan99"
	ifconfig_fxp0="inet 158.250.XX.XX netmask 255.255.255.224"
	ifconfig_vlan99="inet 192.168.XX.XX netmask 255.255.255.0 vlan 99 vlandev fxp1"
%%% rc(8) output %%%

	vlan99: bpf attached
	ifconfig: SIOCSETVLAN: Device busy
	fxp0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
		inet 158.250.32.111 netmask 0xffffffe0 broadcast 158.250.32.127
		ether 00:04:ac:98:a7:b9
		media: Ethernet autoselect (100baseTX <full-duplex>)
		status: active
	lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
		inet 127.0.0.1 netmask 0xff000000
	vlan99: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
		inet 169.254.1.1 netmask 0xffff0000 broadcast 169.254.255.255
		ether 00:90:27:a6:97:e9
		media: Ethernet autoselect (none)
		status: no carrier
		vlan: 99 parent interface: fxp1
	vlan99: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
		inet 169.254.1.1 netmask 0xffff0000 broadcast 169.254.255.255
		ether 00:90:27:a6:97:e9
		media: Ethernet autoselect (none)
		status: no carrier
		vlan: 99 parent interface: fxp1

%%% end of example %%%

	Things to note are:

	(1) "SIOCSETVLAN: Device busy" from ifconfig when it tried
	    to set VLAN parameters on vlan99 for the second time;

	(2) vlan99 appearing twice in the status display.

>Fix:

	I can see a few ways to address this issue:

	(1) list_net_interfaces() could eliminate duplicates from
	    the list of interface names to return.

	(2) The automatic list of interfaces could be saved early,
	    before cloning.

	(3) A flag variable could be introduced to tell whether cloned
	    interfaced have been created.

	Each route is easy to implement, but I'm afraid I don't know
	the internals of rcNG well enough to choose the best one.
>Release-Note:
>Audit-Trail:
>Unformatted: