openpty() and jail in RELENG_7

Vlad GALU dudu at dudu.ro
Wed Nov 7 06:48:45 PST 2007


On 11/7/07, Tom Evans <tevans.uk at googlemail.com> wrote:
> On Tue, 2007-11-06 at 22:19 +0200, Dan Epure wrote:
> > Hi All,
> >
> >
> > I'm using on the host system (7.0-BETA2):
> > #sysctl kern.pts.enable
> > kern.pts.enable: 1
> > I have no problem at all.
> >
> > The jail is also 7.0-BETA2
> >
> > The problem is inside the jail openpty() can not allocate the pty:
> > === cut here ===
> > debug1: monitor_child_preauth: test2 has been authenticated by privileged process
> > debug1: PAM: reinitializing credentials
> > debug1: Entering interactive session for SSH2.
> > debug1: server_init_dispatch_20
> > debug1: server_input_channel_open: ctype session rchan 0 win 65536 max 16384
> > debug1: input_session_request
> > debug1: channel 0: new [server-session]
> > debug1: session_new: init
> > debug1: session_new: session 0
> > debug1: session_open: channel 0
> > debug1: session_open: session 0: link with channel 0
> > debug1: server_input_channel_open: confirm session
> > debug1: server_input_channel_req: channel 0 request pty-req reply 0
> > debug1: session_by_channel: session 0 channel 0
> > debug1: session_input_channel_req: session 0 req pty-req
> > debug1: Allocating pty.
> > debug1: session_new: init
> > debug1: session_new: session 0
> > openpty: No such file or directory
> > session_pty_req: session 0 alloc failed
> > debug1: server_input_channel_req: channel 0 request shell reply 0
> > debug1: session_by_channel: session 0 channel 0
> > debug1: session_input_channel_req: session 0 req shell
> > === and here ===
> > the ssh session just hangs. (no pty ?)
> >
> > I did not forget to mount devfs inside the jail.
> > The jail is configured in rc.conf:
> > === cut here ===
> > jail_enable="YES"
> > jail_list="test"
> > jail_test_hostname="test.mydomain.org"
> > jail_test_rootdir="/jails/test"
> > jail_test_interface="bge0"
> > jail_test_devfs_enable="YES"
> > jail_test_ip="192.168.10.2"
> > jail_set_hostname_allow="NO"
> > jail_sysvipc_allow="NO"
> > jail_socket_unixiproute_only="YES"
> > === and here ===
> > I think the problem is related to restrictions imposed by the jail.
> >
> > Please advise.
> >
> > Gepu
>
> This is because you haven't been allocated a pty inside your jail.
> Enable sshd inside your jail, ssh to your jail (which will allocate you
> a pty). Then from inside your jail, you can use any pty-using
> application you wish.
>
> I am presuming you are doing something like 'jexec 1 /bin/csh' or
> similar, and I'm only really repeating Xin Li's advice to me[1].
>
> Cheers
>
> Tom
>
> [1]
> http://lists.freebsd.org/pipermail/freebsd-jail/2007-October/000106.html
>
>

    I'm chiming in to signal a possibly related problem. Logging in
and out via sshd behaves normally (ie: the ptys are cleaned up
accordingly) but opening virtual consoles in screen and then closing
them does not, thus leading to starvation.


-- 
Mahnahmahnah!


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