misc/109912: mountd(8) does not accept identical network address-mask pairs on different mount entries on the same file system

[Antuan Avdioukhine]

>Number:         109912
>Category:       misc
>Synopsis:       mountd(8) does not accept identical network address-mask pairs on different mount entries on the same file system
>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:   Mon Mar 05 10:50:02 GMT 2007
>Closed-Date:
>Last-Modified:
>Originator:     Antuan Avdioukhine
>Release:        FreeBSD 5.5-STABLE i386
>Organization:
TC Convey Plus
>Environment:
System: FreeBSD tyger.cplus.ru 5.5-STABLE FreeBSD 5.5-STABLE #2: Sat Mar 3 18:54:38 MSK 2007 toor at tyger.cplus.ru:/usr/obj/usr/src/sys/TYGER i386


>Description:
If /etc/exports contains mount entries, belongs to one file system and
exported for identical host groups or networks mountd(8) produces an error
"can't change attributes for <mountpoint path>" and "bad export line
<mountpoint path>" for each mount entry but first. This is happens whether
different mount options was used or not.

>How-To-Repeat:

1. Create two directories for mount points on the same file system, eg:
/tmp/u1 and /tmp/u2, check that this directories are suitable for export
(eg. have proper permissions) and no other filesystems mounted on this
directories.

2. Start NFS server as usual. Check that syslog catches daemon facility at
notice level or lower. mountd started with flags: -l -r -n

3. create /etc/exports file entries:

/tmp/u1 10.0.0.1
/tmp/u2 10.0.0.1

4. run 'kill -1 `head -1 /var/run/montd.pid`'

5. Check log for mountd reporting. It is expected to see messages:
Mar  5 13:02:35 tyger mountd[50813]: can't change attributes for /tmp/u2
Mar  5 13:02:35 tyger mountd[50813]: bad exports list line /tmp/u2 10.0.0.1

You may also change host sets from single host to list of hosts or networks,
with the only condition: if you are using networks, all networks must be
with identical addreses and masks.

>Fix:

Workaround:

For host sets specified with network-mask pair it is possible to split
network using longer masks, eg. 

/tmp/u1 -network 10.0.0.0 -mask 255.255.255.0
/tmp/u2 -network 10.0.0.0 -mask 255.255.255.128
/tmp/u2 -network 10.0.0.128 -mask 255.255.255.128

I don't know suitable workaround for host sets specified with host lists.


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