netdev - Re: [patch net-next-2.6 1/2] net: allow to change carrier via sysfs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1314717262.2752.11.camel@bwh-desktop>
Date:	Tue, 30 Aug 2011 16:14:22 +0100
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	Jiri Pirko <jpirko@...hat.com>
Cc:	netdev@...r.kernel.org, davem@...emloft.net,
	eric.dumazet@...il.com, shemminger@...tta.com
Subject: Re: [patch net-next-2.6 1/2] net: allow to change carrier via sysfs

On Tue, 2011-08-30 at 16:46 +0200, Jiri Pirko wrote:
> Allow to write to "carrier" attribute. Devices may implement ndo_change_carrier
> callback to allow changing carrier from userspace.
[...]
> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
> index 56e42ab..c8f2ca4 100644
> --- a/net/core/net-sysfs.c
> +++ b/net/core/net-sysfs.c
> @@ -126,6 +126,30 @@ static ssize_t show_broadcast(struct device *dev,
>  	return -EINVAL;
>  }
>  
> +static ssize_t store_carrier(struct device *dev, struct device_attribute *attr,
> +			     const char *buf, size_t len)
> +{
> +	struct net_device *netdev = to_net_dev(dev);
> +	ssize_t ret;
> +	int new_value;
> +
> +	if (!capable(CAP_NET_ADMIN))
> +		return -EPERM;
> +
> +	if (!netif_running(netdev))
> +		return -EINVAL;

Not sure that's the right error code.

> +	if (sscanf(buf, "%d", &new_value) != 1)
> +		return -EINVAL;

kstrtoint()

(Or maybe we should have kstrobool().)

> +	if (!rtnl_trylock())
> +		return restart_syscall();
[...]

This is consistent with other attributes, but it seems like a really bad
practice as it will generally result in the process busy-waiting on the
RTNL lock!  I think it would be better to add and use an
rtnl_lock_interruptible().

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html