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

[Paul Moore <paul.moore@hp.com>]

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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