error: ssh_selinux_getctxbyname: Failed to get default SELinux security context

[Dominick Grift]

On Tue, Sep 28, 2010 at 03:51:11PM +0200, imsand at puzzle.ch wrote:
> > On Tue, Sep 28, 2010 at 01:56:13PM +0200, imsand at puzzle.ch wrote:
> >> > On 28/09/10 08:24, imsand at puzzle.ch wrote:
> >> >> Hello
> >> >>
> >> >> I get the following error when I try to log in through ssh (even if
> >> >> selinux is in permissive mode!!!):
> >> >>
> >> >> Sep 28 09:01:32 stvlx05.test.ch sshd[12614]: Accepted
> >> >> keyboard-interactive/pam for mat from 131.102.233.127 port 58912 ssh2
> >> >> Sep 28 09:01:32 stvlx05.test.admin.ch kernel: [60557.252750]
> >> type=1400
> >> >> audit(1285657292.298:286): avc:  denied  { audit_control } for
> >> >> pid=12614
> >> >> comm="sshd" capability=30  scontext=system_u:system_r:sysadm_t
> >> >> tcontext=system_u:system_r:sysadm_t tclass=capability
> >> >> Sep 28 09:01:32 stvlx05.test.ch sshd[12621]: error:
> >> >> ssh_selinux_getctxbyname: Failed to get default SELinux security
> >> context
> >> >> for mat
> >> >> Sep 28 09:01:32 stvlx05.test.ch sshd[12614]: error:
> >> >> ssh_selinux_getctxbyname: Failed to get default SELinux security
> >> context
> >> >> for mat
> >> >> Sep 28 09:01:32 stvlx05.test.ch sshd[12614]: error:
> >> >> ssh_selinux_setup_pty:
> >> >> security_compute_relabel: Invalid argument
> >> >>
> >> >> I already went through this post:
> >> >> http://www.nsa.gov/research/selinux/list-archive/0910/30906.shtml but
> >> I
> >> >> can't figure out the exact problem.
> >> >>
> >> >> Here is what I've done so far:
> >> >> - Downloaded the latest reference policy from tresys:
> >> >> http://oss.tresys.com/files/refpolicy/refpolicy-2.20100524.tar.bz2
> >> >> - Compiled and installed it on my sles 11.1
> >> >> - set selinux into permissive mode: (so far so good.. :))
> >> >> sestatus
> >> >> SELinux status:                 enabled
> >> >> SELinuxfs mount:                /selinux
> >> >> Current mode:                   permissive
> >> >> Mode from config file:          permissive
> >> >> Policy version:                 24
> >> >> Policy from config file:        refpolicy
> >> >> - Add selinux user "mat_u": semanage user -R "staff_r system_r" -P
> >> user
> >> >> -a
> >> >> mat_u
> >> >> - Add linux user " mat": useradd mat
> >> >> - Set password for "mat": passwd mat
> >> >> - User mapping: semanage login -s mat_u -a mat
> >> >> - add security context for "mat_u" by copying staff_u's context
> >> (don't
> >> >> know if that's needed??!): cp
> >> >> /etc/selinux/refpolicy/contexts/user/staff_u
> >> >> /etc/selinux/refpolicy/contexts/user/mat_u
> >> >> - set boolean for sysadm ssh login to true (don't know if thats
> >> >> needed?!):
> >> >> setsebool ssh_sysadm_login on
> >> >>
> >> >> In other posts I've read something about sepermit.conf and
> >> >> namespace.conf
> >> >> but these files don't exist on my system. What about these files? Do
> >> I
> >> >> need them?
> >> >> What's wrong on my system?
> >> >> Why it's not possible to login even if selinux is in permissive mode?
> >> >> Any suggestions?
> >> >
> >> > I'd start by trying to figure out why sshd isn't running in sshd_t (it
> >> > seems to be running in sysadm_t).
> >> >
> >> > Paul.
> >> > --
> >> > selinux mailing list
> >> > selinux at lists.fedoraproject.org
> >> > https://admin.fedoraproject.org/mailman/listinfo/selinux
> >> >
> >>
> >> Yes, sshd is running in sysadm_t:
> >>
> >> # ps axZ | grep sshd
> >> system_u:system_r:sysadm_t       3632 ?        Ss     0:00
> >> /usr/sbin/sshd
> >> -o PidFile=/var/run/sshd.init.pi
> >>
> >> # ls -Z /usr/sbin/sshd
> >> system_u:object_r:sshd_exec_t /usr/sbin/sshd
> >>
> >> Don't know why it's not sshd_t. I didn't modified something. It's a
> >> standard installation of sles11 with the default reference policy from
> >> tresys.
> >>
> >> Maybe this code snippet from policy/modules/services/ssh.te is
> >> responsible
> >> for that:
> >> ## <desc>
> >> ## <p>
> >> ## Allow ssh logins as sysadm_r:sysadm_t
> >> ## </p>
> >> ## </desc>
> >> gen_tunable(ssh_sysadm_login, true)
> >>
> >> Any ideas?
> >
> > Do you have boolean init_upstart set to on? if not try setting it to on.
> > I do not believe ssh_sysadm_login boolean works currently but i may be
> > mistaken.

ssh_sysadm_login DOES actually work you just need to specify your role on login...

> >>
> >> --
> Yeah, setting init_upstart to on did the trick! THANK A LOT!
> Do you know why this prevents the user from logging in through ssh even if
> selinux is set to permissive??
> 
> --
> selinux mailing list
> selinux at lists.fedoraproject.org
> https://admin.fedoraproject.org/mailman/listinfo/selinux
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