netdev - Re: [net-next-2.6 PATCH 3/3 RFC] macvtap: Add support for TUNSETTXFILTER

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Message-Id: <201109081825.31065.arnd@arndb.de>
Date:	Thu, 8 Sep 2011 18:25:30 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Roopa Prabhu <roprabhu@...co.com>
Cc:	netdev@...r.kernel.org, dragos.tatulea@...il.com, mst@...hat.com,
	dwang2@...co.com, benve@...co.com, kaber@...sh.net, sri@...ibm.com
Subject: Re: [net-next-2.6 PATCH 3/3 RFC] macvtap: Add support for TUNSETTXFILTER

On Wednesday 07 September 2011, Roopa Prabhu wrote:
> From: Roopa Prabhu <roprabhu@...co.com>
> 
> This patch adds support for TUNSETTXFILTER. Calls macvlan set filter function
> with address list and flags received via TUNSETTXFILTER.
> 
> Signed-off-by: Roopa Prabhu <roprabhu@...co.com>
> Signed-off-by: Christian Benvenuti <benve@...co.com>
> Signed-off-by: David Wang <dwang2@...co.com>

Looks ok to me in principle, but

> +               /* XXX: If broadcast address present, set IFF_BROADCAST */
> +               /* XXX: If multicast address present, set IFF_MULTICAST */
> +               flags |= (tf.flags & TUN_FLT_ALLMULTI ? IFF_ALLMULTI : 0) |
> +                        (!tf.count ? IFF_PROMISC : 0);
> +               ret = 0;
> +               if (tf.count > 0) {
> +                       alen = ETH_ALEN * tf.count;
> +                       addrs = kmalloc(alen, GFP_KERNEL);
> +                       if (!addrs) {
> +                               dev_put(vlan->dev);
> +                               return -ENOMEM;
> +                       }

I think you need to check tf.count for a maximum value. In theory, a user
could pass a rather large number (65536) which is not good.

Also the TUNSETTXFILTER code looks sufficiently large that it would be
better to put it into a separate function. Use "goto" statements in
order to do the error handling in there, instead of repeating
lots of kfree and dev_put calls in each error case.

	Arnd
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