Subject: Re: [RFC] let mortals use ethtool

From: Auke Kok <[email-masked]>
Date: Thu, 28 Sep 2006 12:56:25 -0700

Stephen Hemminger wrote:
> There is no reason to not allow non-admin users to query network
> statistics and settings.
> 
> 
> --- linux-2.6.orig/net/core/ethtool.c
> +++ linux-2.6/net/core/ethtool.c
> @@ -806,13 +806,6 @@ int dev_ethtool(struct ifreq *ifr)
>  	int rc;
>  	unsigned long old_features;
>  
> -	/*
> -	 * XXX: This can be pushed down into the ethtool_* handlers that
> -	 * need it.  Keep existing behaviour for the moment.
> -	 */
> -	if (!capable(CAP_NET_ADMIN))
> -		return -EPERM;
> -
>  	if (!dev || !netif_device_present(dev))
>  		return -ENODEV;
>  
> @@ -822,6 +815,33 @@ int dev_ethtool(struct ifreq *ifr)
>  	if (copy_from_user(&ethcmd, useraddr, sizeof (ethcmd)))
>  		return -EFAULT;
>  
> +	/* Allow some commands to be done by anyone */
> +	switch(ethcmd) {
> +	case ETHTOOL_GSET:
> +	case ETHTOOL_GDRVINFO:
> +	case ETHTOOL_GREGS:
> +	case ETHTOOL_GWOL:
> +	case ETHTOOL_GMSGLVL:
> +	case ETHTOOL_GLINK:
> +	case ETHTOOL_GCOALESCE:
> +	case ETHTOOL_GRINGPARAM:
> +	case ETHTOOL_GPAUSEPARAM:
> +	case ETHTOOL_GRXCSUM:
> +	case ETHTOOL_GTXCSUM:
> +	case ETHTOOL_GSG:
> +	case ETHTOOL_GSTRINGS:
> +	case ETHTOOL_PHYS_ID:

PHYS_ID pokes in hardware and makes it jump through hoops, in the case of some hardware 
this could create a local DOS attack (e1000 suffers fromt his, probably more if not all) 
where the NIC might stop receiving packets, or the big lock is help indefinately.

Not a good idea

The other ones are fine I think.

Auke

> +	case ETHTOOL_GSTATS:
> +	case ETHTOOL_GTSO:
> +	case ETHTOOL_GPERMADDR:
> +	case ETHTOOL_GUFO:
> +	case ETHTOOL_GGSO:
> +		break;
> +	default:
> +		if (!capable(CAP_NET_ADMIN))
> +			return -EPERM;
> +	}
> +
>  	if(dev->ethtool_ops->begin)
>  		if ((rc = dev->ethtool_ops->begin(dev)) < 0)
>  			return rc;
> @@ -947,6 +967,10 @@ int dev_ethtool(struct ifreq *ifr)
>  	return rc;
>  
>   ioctl:
> +	/* Keep existing behaviour for the moment.	 */
> +	if (!capable(CAP_NET_ADMIN))
> +		return -EPERM;
> +
>  	if (dev->do_ioctl)
>  		return dev->do_ioctl(dev, ifr, SIOCETHTOOL);
>  	return -EOPNOTSUPP;
> -
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