Re: [RFC] ssh: remove unconfined_shell_domtrans(sshd_t)

[Nicolas Iooss <nicolas.iooss@m4x.org>]

On Sat, Aug 31, 2019 at 10:54 PM Chris PeBenito <pebenito@ieee.org> wrote:
>
> On 8/31/19 1:27 PM, Dominick Grift wrote:
> > This call allows sshd_t associated processes with run shell with an automatic domain transition to unconfined_t.
> > I was unable to make sense of the commit that added this:
> >
> > https://github.com/SELinuxProject/refpolicy/commit/708aab13932bb8830a2d37850cc0a5c72a5d4df4
> >
> > Debian's motd dynamic pam module makes sshd run a shell, we want this shell to run with sshd_t instead of unconfined_t
> >
> > This patch will make the ssh_sysadm_login boolean apply to unconfined ssh logins.
> > To me this makes sense, as unconfined_t is targeted equivalent to the strict sysadm_t.
> > The boolean could however be renamed to the more generic ssh_priv_login name.
> >
> > Signed-off-by: Dominick Grift <dac.override@gmail.com>
> > ---
> >   policy/modules/services/ssh.te | 4 ----
> >   1 file changed, 4 deletions(-)
> >
> > diff --git a/policy/modules/services/ssh.te b/policy/modules/services/ssh.te
> > index 4e75b6e1..a99ad912 100644
> > --- a/policy/modules/services/ssh.te
> > +++ b/policy/modules/services/ssh.te
> > @@ -328,10 +328,6 @@ optional_policy(`
> >       systemd_dbus_chat_logind(sshd_t)
> >   ')
> >
> > -optional_policy(`
> > -     unconfined_shell_domtrans(sshd_t)
> > -')
> > -
> >   optional_policy(`
> >       xserver_domtrans_xauth(sshd_t)
> >       xserver_link_xdm_keys(sshd_t)
>
> I don't have any objections to this.

Would it be possible to extend this patch to other callers of
unconfined_shell_domtrans, like the patch below? It will help fix
issues with Debian's PAM module that generates the MOTD (Message Of
The Day) in a dynamic way, using shell commands (cf.
https://wiki.debian.org/motd for more information: calling system()
triggers a transition to system_u:system_r:unconfined_t because of
unconfined_shell_domtrans).

diff --git a/policy/modules/services/remotelogin.te
b/policy/modules/services/remotelogin.te
index bc2292e37892..c7c9c5646785 100644
--- a/policy/modules/services/remotelogin.te
+++ b/policy/modules/services/remotelogin.te
@@ -91,10 +91,6 @@ optional_policy(`
  telnet_use_ptys(remote_login_t)
 ')

-optional_policy(`
- unconfined_shell_domtrans(remote_login_t)
-')
-
 optional_policy(`
  usermanage_read_crack_db(remote_login_t)
 ')
diff --git a/policy/modules/services/rshd.te b/policy/modules/services/rshd.te
index 0f4caffc4f33..196ed2848e4b 100644
--- a/policy/modules/services/rshd.te
+++ b/policy/modules/services/rshd.te
@@ -74,6 +74,5 @@ optional_policy(`
 ')

 optional_policy(`
- unconfined_shell_domtrans(rshd_t)
  unconfined_signal(rshd_t)
 ')
diff --git a/policy/modules/system/locallogin.te
b/policy/modules/system/locallogin.te
index a56f3d1fbe16..632d2542972d 100644
--- a/policy/modules/system/locallogin.te
+++ b/policy/modules/system/locallogin.te
@@ -200,10 +200,6 @@ optional_policy(`
  systemd_write_inherited_logind_sessions_pipes(local_login_t)
 ')

-optional_policy(`
- unconfined_shell_domtrans(local_login_t)
-')
-
 optional_policy(`
  usermanage_read_crack_db(local_login_t)
 ')