svn commit: r199201 - in head: contrib/libpcap sbin/ifconfig share/man/man4 sys/kern sys/net sys/sys

[John Baldwin]

On Wednesday 11 November 2009 4:30:58 pm Xin LI wrote:
> Author: delphij
> Date: Wed Nov 11 21:30:58 2009
> New Revision: 199201
> URL: http://svn.freebsd.org/changeset/base/199201
> 
> Log:
>   Add interface description capability as inspired by OpenBSD.
>   
>   MFC after:	3 months
> 
> Modified: head/sys/net/if.c
> ==============================================================================
> --- head/sys/net/if.c	Wed Nov 11 21:18:27 2009	(r199200)
> +++ head/sys/net/if.c	Wed Nov 11 21:30:58 2009	(r199201)
> @@ -2090,6 +2092,45 @@ ifhwioctl(u_long cmd, struct ifnet *ifp,
>  		ifr->ifr_phys = ifp->if_physical;
>  		break;
>  
> +	case SIOCSIFDESCR:
> +		error = priv_check(td, PRIV_NET_SETIFDESCR);
> +		if (error)
> +			return (error);
> +
> +		IF_AFDATA_WLOCK(ifp);
> +		if (ifp->if_description == NULL) {
> +			ifp->if_description = sbuf_new_auto();
> +			if (ifp->if_description == NULL) {
> +				error = ENOMEM;
> +				IF_AFDATA_WUNLOCK(ifp);
> +				break;
> +			}
> +		} else
> +			sbuf_clear(ifp->if_description);
> +
> +		if (sbuf_copyin(ifp->if_description, ifr->ifr_buffer.buffer,
> +				ifr->ifr_buffer.length) == -1)
> +			error = EFAULT;
> +
> +		if (error == 0) {
> +			sbuf_finish(ifp->if_description);
> +			getmicrotime(&ifp->if_lastchange);
> +		}
> +		IF_AFDATA_WUNLOCK(ifp);

Since IF_AFDATA isn't a sleepable lock (e.g. an sx lock), it is not safe
to do a copyin() while holding this lock.  A better approach would probably
be something like:

	struct sbuf *new, *old;

	case SIOCSIFDESCR:
		/* priv check */

		new = sbuf_new_auto();
		if (new == NULL)
			return (ENOMEM);
		if (sbuf_copyin(new, ifr->ifr_buffer.buffer,
		    ifr->ifr_buffer.length) == -1) {
			sbuf_delete(new);
			return (EFAULT);
		}

		IF_AFDATA_WLOCK(ifp);
		old = ifp->if_description;
		ifp->if_description = new;
		getmicrotime(&ifp->if_lastchange);
		IF_AFDATA_WUNLOCK(ifp);
		if (old != NULL)
			sbuf_delete(old);
		break;

-- 
John Baldwin