devfs not mounting in nullfs jail

S

scottro

We have our own way of using nullfs to create a template jail, then mount several other jails on top of it. At one point I did a brief write up of it, for my own use, at http://home.roadrunner.com/~computertai ... sjail.html. It's based on this handbook page. http://www.freebsd.org/doc/handbook/jai ... ation.html, but is a bit simpler.

Recently, I tried this on FreeBSD-10. As folks might know, as of FreeBSD-10--actually, the man page has mentioned it earlier, but I've found it to be inconsistent--rather than adding devfs entries to /etc/rc.conf, one adds them to /etc/jail.conf.

While a standard jail works as expected with this, mounting /dev on a jail's /dev directory, the problem is that if I use the template method, where both the template jail, using nullfs and the new jail are both mounted on say, /jails/_jails1, devfs doesn't get properly mounted. If I use the mount command, it will show me that devfs is mounted where I want it to be, on jails/_jail1/dev, all I see on jails/_jail1/dev is null and log. I can then manually mount devfs with the mount -t devfs -o dev /jails/_jail1/dev
and devfs is mounted, (which makes me suspect that I've missed something somewhere.)
My /etc/jail.conf which works without problem with a standard jail is
Code: 
jail1 {
      path = /jails/_jail1;
      mount.devfs;
     devfs_ruleset = 4;
     ip4.addr = 192.168.1.196;
     exec.start = "/bin/sh /etc/rc";
     exec stop = "/bin/sh etc/rc.shutdown";
I've been able to duplicate this on two machines, but before filing a pr, I'd like to do my best to confirm it's not something that I've missed.
 
Last edited:
I've been at this a couple of day now. Also tried adding the devfs lines to /etc/rc.conf and that had no luck. A kludgy workaround for anyone else in the same fix, is to add a line to mount devfs in each jail in an /etc/rc.local, but so far, that's the only working solution I've come across. I've seen a couple of other posts about jails in FreeBSD-10, though none exactly like this. For what it's worth, if I don't use nullfs, jails work well with the new /etc/jail.conf, devfs mounting as expected.
 
Don't know if this is solved or not, but after I followed the steps listed in the nullfs jail tutorial I did have /dev properly mounted in my jail. This is without the additional /etc/rc.local using FreeBSD 10.0-RELEASE compiled from revision 262433 sources.

UPDATE: just created a new jail and now /dev is not properly mounted. Back to adding the special mount in /etc/rc.local
 
Great, and thank you for letting me know. I'm going to (though not sure if I will tonight), try updating world and seeing if it helps.
 
I just did a buildworld, bringing me to Revision 262459 and still no luck for me. Thank you again for responding.
 
For anyone still looking at this, on the PR mentioned in my earlier post, http://www.freebsd.org/cgi/query-pr.cgi?pr=186360, someone has mentioned a solution. In the jail.conf file, I can add
Code: 
exec.prestart = "ls /jails/_myjail/dev";

The logic behind it is explained in the comment in the PR, but at any rate, adding that line before the exec.start populates a jail's /dev directory. I'm not going to say solved, because I think it shouldn't need the line--and also, it doesn't mount the complete /dev, but does mount enough so that one can ssh to the jail and install packages in it, but it's a start.
 
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