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[NET]: Require CAP_NET_ADMIN to create tuntap devices.

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The tuntap driver allows an admin to create persistent devices and
assign ownership of them to individual users. Unfortunately, relaxing
the permissions on the /dev/net/tun device node so that they can
actually use those devices will _also_ allow those users to create
arbitrary new devices of their own. This patch corrects that, and
adjusts the recommended permissions for the device node accordingly.

Signed-off-By: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David Woodhouse 2006-06-22 16:07:52 -07:00 committed by David S. Miller
parent f4b8ea7849
commit ca6bb5d7ab
2 changed files with 10 additions and 4 deletions
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11
Documentation/networking/tuntap.txt
View file

@ -39,10 +39,13 @@ Copyright (C) 1999-2000 Maxim Krasnyansky <max_mk@yahoo.com>
mknod /dev/net/tun c 10 200
Set permissions:
e.g. chmod 0700 /dev/net/tun
if you want the device only accessible by root. Giving regular users the
right to assign network devices is NOT a good idea. Users could assign
bogus network interfaces to trick firewalls or administrators.
e.g. chmod 0666 /dev/net/tun
There's no harm in allowing the device to be accessible by non-root users,
since CAP_NET_ADMIN is required for creating network devices or for
connecting to network devices which aren't owned by the user in question.
If you want to create persistent devices and give ownership of them to
unprivileged users, then you need the /dev/net/tun device to be usable by
those users.
Driver module autoloading

3
drivers/net/tun.c
View file

@ -490,6 +490,9 @@ static int tun_set_iff(struct file *file, struct ifreq *ifr)
err = -EINVAL;
if (!capable(CAP_NET_ADMIN))
return -EPERM;
/* Set dev type */
if (ifr->ifr_flags & IFF_TUN) {
/* TUN device */