cannot access pass device from within jail

Dan Langille dan at
Sun Dec 17 20:49:43 UTC 2017

> On Dec 17, 2017, at 3:37 PM, Konstantin Belousov <kostikbel at> wrote:
> On Sun, Dec 17, 2017 at 02:52:12PM -0500, Dan Langille wrote:
>> Hello,
>> What suggestions do you have for where I should look next? I'm happy to start installing various builds of FreeBSD in order to track down which commit caused this.
>> I'm trying to access a tape library from within a jail running on a FreeBSD 11.1 host.  sa(4) devices are working (e.g. I can rewind nsa0).
>> pass(4) devices (i.e. the tape changer ch0) are not working.  This morning I posted to -scsi@:
>> The device appears in the jail and has appropriate permissions.  This access was granted
>> via /etc/devfs.rules using the same approach I used for FreeBSD 10.3
>> The permissions in the jail:
>> [root at bacula-sd-02 ~]# ls -l /dev/pass7
>> crw-------  1 root  operator  0x74 Dec 16 21:52 /dev/pass7
>> The command in the jail:
>> [root at bacula-sd-02 ~]# mtx -f /dev/pass7 status 
>> cannot open SCSI device '/dev/pass7' - Operation not permitted
>> Here is the truss output of the command in question:
> Does it work to access the pass device from host using host' /dev ?

Yes, it does. see "This command on the host" at

> Same question for the host access using the nodes of the jailed devfs mount.

I didn't try that, but I will soon. To be clear, does this command on the host look like what you have in mind?

mtx -f /usr/jails/bacula-sd-02/dev/pass7 status 

Dan Langille - BSDCan / PGCon
dan at

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