[PATCH] SELinux: Use unknown perm handling to handle unknown netlink msg types

[PATCH] SELinux: Use unknown perm handling to handle unknown netlink msg types

[Eric Paris]

Currently when SELinux has not been updated to handle a netlink message
type the operation is denied with EINVAL.  This patch will leave the
audit/warning message so things get fixed but if policy chose to allow
unknowns this will allow the netlink operation.

Signed-off-by: Eric Paris <eparis@redhat.com>
---

 security/selinux/hooks.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)


diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index f85597a..c6f8f3e 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4387,7 +4387,7 @@ static int selinux_nlmsg_perm(struct sock *sk, struct sk_buff *skb)
 				  "SELinux:  unrecognized netlink message"
 				  " type=%hu for sclass=%hu\n",
 				  nlh->nlmsg_type, isec->sclass);
-			if (!selinux_enforcing)
+			if (!selinux_enforcing || security_get_allow_unknown())
 				err = 0;
 		}
 



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Re: [PATCH] SELinux: Use unknown perm handling to handle unknown netlink msg types

[Paul Moore]

On Wednesday 05 November 2008 9:34:42 am Eric Paris wrote:
> Currently when SELinux has not been updated to handle a netlink
> message type the operation is denied with EINVAL.  This patch will
> leave the audit/warning message so things get fixed but if policy
> chose to allow unknowns this will allow the netlink operation.
>
> Signed-off-by: Eric Paris <eparis@redhat.com>
> ---
>
>  security/selinux/hooks.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
>
>
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index f85597a..c6f8f3e 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -4387,7 +4387,7 @@ static int selinux_nlmsg_perm(struct sock *sk,
> struct sk_buff *skb) "SELinux:  unrecognized netlink message"
>  				  " type=%hu for sclass=%hu\n",
>  				  nlh->nlmsg_type, isec->sclass);
> -			if (!selinux_enforcing)
> +			if (!selinux_enforcing || security_get_allow_unknown())
>  				err = 0;
>  		}

What about moving the security_get_allow_unknown() call to the default 
switch clause of selinux_nlmsg_lookup()?  Something like this:

        /* No messaging from userspace, or class unknown/unhandled */
        default:
                if (!security_get_allow_unknown())
			err = -ENOENT;
                break;

This seems like a more natural fit to me (although maybe the audit 
message should be moved to selinux_nlmsg_lookup() too?) and it has the 
benefit of still checking the socket permissions via socket_has_perm() 
in the event that the netlink message is unknown.

-- 
paul moore
linux @ hp

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Re: [PATCH] SELinux: Use unknown perm handling to handle unknown netlink msg types

[Eric Paris]

On Wed, 2008-11-05 at 11:38 -0500, Paul Moore wrote:
> On Wednesday 05 November 2008 9:34:42 am Eric Paris wrote:
> > Currently when SELinux has not been updated to handle a netlink
> > message type the operation is denied with EINVAL.  This patch will
> > leave the audit/warning message so things get fixed but if policy
> > chose to allow unknowns this will allow the netlink operation.
> >
> > Signed-off-by: Eric Paris <eparis@redhat.com>
> > ---
> >
> >  security/selinux/hooks.c |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> >
> >
> > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> > index f85597a..c6f8f3e 100644
> > --- a/security/selinux/hooks.c
> > +++ b/security/selinux/hooks.c
> > @@ -4387,7 +4387,7 @@ static int selinux_nlmsg_perm(struct sock *sk,
> > struct sk_buff *skb) "SELinux:  unrecognized netlink message"
> >  				  " type=%hu for sclass=%hu\n",
> >  				  nlh->nlmsg_type, isec->sclass);
> > -			if (!selinux_enforcing)
> > +			if (!selinux_enforcing || security_get_allow_unknown())
> >  				err = 0;
> >  		}
> 
> What about moving the security_get_allow_unknown() call to the default 
> switch clause of selinux_nlmsg_lookup()?  Something like this:
> 
>         /* No messaging from userspace, or class unknown/unhandled */
>         default:
>                 if (!security_get_allow_unknown())
> 			err = -ENOENT;
>                 break;
> 
> This seems like a more natural fit to me (although maybe the audit 
> message should be moved to selinux_nlmsg_lookup() too?) and it has the 
> benefit of still checking the socket permissions via socket_has_perm() 
> in the event that the netlink message is unknown.

We already just blindly allow the case where a new/unknown sclass is
used which is what this part of the switch statement hits.  I wanted to
get the case where a known class has a new mesg type (aka nlmsg_perm
returns -EINVAL)

Not sure that the socket check is worth anything since I don't (in
either case) know what perms to ask for.

I also considered making the case of unknown msg type return ALL of the
perms for that entire socket class but I think what I did is the
best/easiest way we can go....

-Eric


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Re: [PATCH] SELinux: Use unknown perm handling to handle unknown netlink msg types

[Stephen Smalley]

On Wed, 2008-11-05 at 09:34 -0500, Eric Paris wrote:
> Currently when SELinux has not been updated to handle a netlink message
> type the operation is denied with EINVAL.  This patch will leave the
> audit/warning message so things get fixed but if policy chose to allow
> unknowns this will allow the netlink operation.
> 
> Signed-off-by: Eric Paris <eparis@redhat.com>

Acked-by:  Stephen Smalley <sds@tycho.nsa.gov>

> ---
> 
>  security/selinux/hooks.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> 
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index f85597a..c6f8f3e 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -4387,7 +4387,7 @@ static int selinux_nlmsg_perm(struct sock *sk, struct sk_buff *skb)
>  				  "SELinux:  unrecognized netlink message"
>  				  " type=%hu for sclass=%hu\n",
>  				  nlh->nlmsg_type, isec->sclass);
> -			if (!selinux_enforcing)
> +			if (!selinux_enforcing || security_get_allow_unknown())
>  				err = 0;
>  		}
>  
> 
-- 
Stephen Smalley
National Security Agency


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Re: [PATCH] SELinux: Use unknown perm handling to handle unknown netlink msg types

[Paul Moore]

On Friday 07 November 2008 11:07:41 am Eric Paris wrote:
> On Wed, 2008-11-05 at 11:38 -0500, Paul Moore wrote:
> > On Wednesday 05 November 2008 9:34:42 am Eric Paris wrote:
> > > Currently when SELinux has not been updated to handle a netlink
> > > message type the operation is denied with EINVAL.  This patch
> > > will leave the audit/warning message so things get fixed but if
> > > policy chose to allow unknowns this will allow the netlink
> > > operation.
> > >
> > > Signed-off-by: Eric Paris <eparis@redhat.com>
> > > ---
> > >
> > >  security/selinux/hooks.c |    2 +-
> > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > >
> > >
> > > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> > > index f85597a..c6f8f3e 100644
> > > --- a/security/selinux/hooks.c
> > > +++ b/security/selinux/hooks.c
> > > @@ -4387,7 +4387,7 @@ static int selinux_nlmsg_perm(struct sock
> > > *sk, struct sk_buff *skb) "SELinux:  unrecognized netlink
> > > message" " type=%hu for sclass=%hu\n",
> > >  				  nlh->nlmsg_type, isec->sclass);
> > > -			if (!selinux_enforcing)
> > > +			if (!selinux_enforcing || security_get_allow_unknown())
> > >  				err = 0;
> > >  		}
> >
> > What about moving the security_get_allow_unknown() call to the
> > default switch clause of selinux_nlmsg_lookup()?  Something like
> > this:
> >
> >         /* No messaging from userspace, or class unknown/unhandled
> > */ default:
> >                 if (!security_get_allow_unknown())
> > 			err = -ENOENT;
> >                 break;
> >
> > This seems like a more natural fit to me (although maybe the audit
> > message should be moved to selinux_nlmsg_lookup() too?) and it has
> > the benefit of still checking the socket permissions via
> > socket_has_perm() in the event that the netlink message is unknown.
>
> We already just blindly allow the case where a new/unknown sclass is
> used which is what this part of the switch statement hits.  I wanted
> to get the case where a known class has a new mesg type (aka
> nlmsg_perm returns -EINVAL)

Fair enough, I thought you were trying to solve a different problem.

-- 
paul moore
linux @ hp

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Re: [PATCH] SELinux: Use unknown perm handling to handle unknown netlink msg types

[James Morris]

On Fri, 7 Nov 2008, Stephen Smalley wrote:

> On Wed, 2008-11-05 at 09:34 -0500, Eric Paris wrote:
> > Currently when SELinux has not been updated to handle a netlink message
> > type the operation is denied with EINVAL.  This patch will leave the
> > audit/warning message so things get fixed but if policy chose to allow
> > unknowns this will allow the netlink operation.
> > 
> > Signed-off-by: Eric Paris <eparis@redhat.com>
> 
> Acked-by:  Stephen Smalley <sds@tycho.nsa.gov>

Applied to
git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6#next

-- 
James Morris
<jmorris@namei.org>

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