From: Ben Hutchings <bhutchings-s/n/eUQHGBpZroRs9YW3xA@public.gmane.org>
To: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
Cc: netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Linux Containers
<containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>,
David Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
Subject: Re: [PATCH net-next 09/17] net: Allow userns root control of the core of the network stack.
Date: Sat, 17 Nov 2012 00:28:36 +0000 [thread overview]
Message-ID: <1353112116.2743.79.camel@bwh-desktop.uk.solarflarecom.com> (raw)
In-Reply-To: <871uft8vpm.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
On Fri, 2012-11-16 at 06:32 -0800, Eric W. Biederman wrote:
> Glauber Costa <glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org> writes:
>
> > On 11/16/2012 05:03 PM, Eric W. Biederman wrote:
> >> + if (!capable(CAP_NET_ADMIN))
> >> + return -EPERM;
> >> +
> >> return netdev_store(dev, attr, buf, len, change_tx_queue_len);
> >
> > You mean ns_capable here?
>
> No. There I meant capable.
>
> I deliberately call capable here because I don't understand what
> the tx_queue_len well enough to be certain it is safe to relax
> that check to be just ns_capable.
>
> My get feel is that allowing an unprivileged user to be able to
> arbitrarily change the tx_queue_len on a networking device would be a
> nice way to allow queuing as many network packets as you would like with
> kernel memory and DOSing the machine.
>
> So since with a quick read of the code I could not convince myself it
> was safe to allow unprivilged users to change tx_queue_len I left it
> protected by capable. While at the same time I relaxed the check in
> netdev_store to be ns_capable.
Tor the same reason you had better be very selective about which ethtool
commands are allowed based on per-user_ns CAP_NET_ADMIN. Consider for a
start:
ETHTOOL_SMSGLVL => fill up the system log
ETHTOOL_SEEPROM => brick the NIC
ETHTOOL_FLASHDEV => brick the NIC; own the system if it's not using an IOMMU
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.
next prev parent reply other threads:[~2012-11-17 0:28 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-16 13:01 [PATCH net-next 0/17] Make the network stack usable by userns root Eric W. Biederman
[not found] ` <87d2zd8zwn.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2012-11-16 13:02 ` [PATCH net-next 01/17] netns: Deduplicate and fix copy_net_ns when !CONFIG_NET_NS Eric W. Biederman
2012-11-16 13:02 ` [PATCH net-next 02/17] userns: make each net (net_ns) belong to a user_ns Eric W. Biederman
[not found] ` <1353070992-5552-1-git-send-email-ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2012-11-16 13:02 ` [PATCH net-next 03/17] sysctl: Pass useful parameters to sysctl permissions Eric W. Biederman
2012-11-16 13:02 ` [PATCH net-next 04/17] net: Don't export sysctls to unprivileged users Eric W. Biederman
2012-11-16 13:03 ` [PATCH net-next 05/17] net: Push capable(CAP_NET_ADMIN) into the rtnl methods Eric W. Biederman
2012-11-16 13:03 ` [PATCH net-next 06/17] net: Update the per network namespace sysctls to be available to the network namespace owner Eric W. Biederman
2012-11-16 13:03 ` [PATCH net-next 07/17] user_ns: get rid of duplicate code in net_ctl_permissions Eric W. Biederman
2012-11-16 13:03 ` [PATCH net-next 08/17] net: Allow userns root to force the scm creds Eric W. Biederman
2012-11-16 13:03 ` [PATCH net-next 10/17] net: Allow userns root to control ipv4 Eric W. Biederman
2012-11-16 13:03 ` [PATCH net-next 11/17] net: Allow userns root to control ipv6 Eric W. Biederman
2012-11-16 13:03 ` [PATCH net-next 12/17] net: Allow userns root to control llc, netfilter, netlink, packet, and xfrm Eric W. Biederman
2012-11-16 13:03 ` [PATCH net-next 14/17] net: Allow the userns root to control vlans Eric W. Biederman
2012-11-16 13:03 ` [PATCH net-next 15/17] net: Enable some sysctls that are safe for the userns root Eric W. Biederman
2012-11-16 13:03 ` [PATCH net-next 16/17] net: Enable a userns root rtnl calls that are safe for unprivilged users Eric W. Biederman
2012-11-16 13:03 ` [PATCH net-next 17/17] net: Make CAP_NET_BIND_SERVICE per user namespace Eric W. Biederman
2012-11-16 13:03 ` [PATCH net-next 09/17] net: Allow userns root control of the core of the network stack Eric W. Biederman
[not found] ` <1353070992-5552-9-git-send-email-ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2012-11-16 13:55 ` Glauber Costa
2012-11-16 14:32 ` Eric W. Biederman
[not found] ` <871uft8vpm.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2012-11-17 0:28 ` Ben Hutchings [this message]
[not found] ` <1353112116.2743.79.camel-/LGg1Z1CJKReKY3V0RtoKmatzQS1i7+A3tAM5lWOD0I@public.gmane.org>
2012-11-17 2:46 ` Eric W. Biederman
[not found] ` <87lie13q18.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2012-11-21 18:29 ` Ben Hutchings
2012-11-16 13:03 ` [PATCH net-next 13/17] net: Allow userns root to control the network bridge code Eric W. Biederman
2012-11-19 3:26 ` [PATCH net-next 0/17] Make the network stack usable by userns root David Miller
[not found] ` <20121118.222601.1683927229305655885.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
2012-11-19 7:27 ` Eric W. Biederman
[not found] ` <87haomkq7q.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2012-11-19 18:52 ` David Miller
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