[PATCH 3/5] audit: add netlink audit protocol bind to check capabilities on multicast join

[Eric Paris]

On Wed, 2014-02-19 at 13:08 -0500, Richard Guy Briggs wrote:
> Register a netlink per-protocol bind fuction for audit to check userspace
> process capabilities before allowing a multicast group connection.
> 
> Signed-off-by: Richard Guy Briggs <rgb at redhat.com>
> ---
>  kernel/audit.c |   10 ++++++++++
>  1 files changed, 10 insertions(+), 0 deletions(-)
> 
> diff --git a/kernel/audit.c b/kernel/audit.c
> index b5b2f72..f2d2d61 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -1050,10 +1050,20 @@ static void audit_receive(struct sk_buff  *skb)
>  	mutex_unlock(&audit_cmd_mutex);
>  }
>  
> +/* Run custom bind function on netlink socket group connect or bind requests. */
> +static int audit_bind(int group)
> +{
> +	if (!capable(CAP_AUDIT_READ))

Not a great idea to use CAP_AUDIT_READ before you define it in patch4

> +		return -EPERM;
> +
> +	return 0;
> +}
> +
>  static int __net_init audit_net_init(struct net *net)
>  {
>  	struct netlink_kernel_cfg cfg = {
>  		.input	= audit_receive,
> +		.bind	= audit_bind,
>  	};
>  
>  	struct audit_net *aunet = net_generic(net, audit_net_id);