Re: [PATCH v2 2/2] ssh: Add interface ssh_search_dir

Dominick Grift <[email protected]> Thu, 20 Jun 2019 17:27:31 +0200
Newsgroups	org.kernel.vger.selinux-refpolicy
Message-ID	<[email protected]>
On Thu, Jun 20, 2019 at 06:05:57PM +0300, Alexander Miroshnichenko wrote:
> On четверг, 20 июня 2019 г. 17:50:11 MSK, Dominick Grift wrote:
> > On Thu, Jun 20, 2019 at 05:41:38PM +0300, Alexander Miroshnichenko wrote:
> > > Create interface ssh_search_dir to allow ssh_server search for keys
> > > in non-standard location.
> > > 
> > > Signed-off-by: Alexander Miroshnichenko <[email protected]>
> > > ---
> > >  policy/modules/services/ssh.if | 18 ++++++++++++++++++
> > >  1 file changed, 18 insertions(+)
> > > 
> > > diff --git a/policy/modules/services/ssh.if
> > > b/policy/modules/services/ssh.if
> > > index 0941f133711e..51c64ded00c4 100644
> > > --- a/policy/modules/services/ssh.if
> > > +++ b/policy/modules/services/ssh.if
> > > @@ -680,6 +680,24 @@ interface(`ssh_agent_exec',`
> > >  	can_exec($1, ssh_agent_exec_t)
> > >  ')
> > > +########################################
> > > +## <summary>
> > > +##      Search for keys in non-standard location
> > > +## </summary>
> > > +## <param name="domain">
> > > +##      <summary>
> > > +##      Domain allowed access.
> > > +##      </summary>
> > > +## </param>
> > > +#
> > > +interface(`ssh_search_dir',`
> > > +        gen_require(`
> > > +                type sshd_t;
> > > +        ')
> > > +
> > > +	allow sshd_t $1:dir search_dir_perms;
> > 
> > This is generally not allowed. The caller should generally be the source.
> > Regardless of the above. Keys should be in user home directories. I
> > wonder what specific scenario prompted you to propose this interface?
> 
> GIT hosting software like gitolite/gitosis/gitea manage users ssh keys and
> store them own location like /var/lib/gitolite/.ssh . /var/lib/gitolite have
> gitosis_var_lib_t type, /var/lib/gitolite/.ssh have gitosis_ssh_home_t type
> (in patched policy which I want to submit).
> If sshd does not have { search getattr } permissions to full path to ssh key
> user fail to login.
> Can you propose corret way to give such permissions to multiple policies?
> It is incorrect to label /var/lib/gitolite as user_home_dir_t type, IMHO.

Yes this sucks. I would probably do the following instead:

1. echo "ignoredirs=/var/lib/gitolite" >> /etc/selinux/semanage.conf
2. semodule -B && restorecon -RvF /var/lib/gitolite
3. gitosis_read_lib_files(sshd_t)

Dont bother with labeling /var/lib/gitolite/.ssh differently

> 
> > > +')
> > > +
> > >  ########################################
> > >  ## <summary>
> > >  ##	Read ssh home directory content ...
> > 
> 

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