Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755649Ab1CAVdW (ORCPT ); Tue, 1 Mar 2011 16:33:22 -0500 Received: from mail-fx0-f46.google.com ([209.85.161.46]:36214 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754757Ab1CAVdU (ORCPT ); Tue, 1 Mar 2011 16:33:20 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=mdPe7VdFKoPV9nFTpzI0jVIAR8nM5LQqoCGKK22ZyEy8+oc1xXkQcgmykqOC5FRlfn lTQ/L8jVuxOWNLamNnOAztlYWKiei77fS0jS78UcxshYY8G974THjDuGCNVm/wYU8Jww jb6rpNyD6e7V+qjA4Lsv7EGRZ8P8rUwdliwVg= Date: Wed, 2 Mar 2011 00:33:13 +0300 From: Vasiliy Kulikov To: linux-kernel@vger.kernel.org Cc: mjt@tls.msk.ru, arnd@arndb.de, mirqus@gmail.com, netdev@vger.kernel.org, Ben Hutchings , David Miller , kuznet@ms2.inr.ac.ru, pekkas@netcore.fi, jmorris@namei.org, yoshfuji@linux-ipv6.org, kaber@trash.net, eric.dumazet@gmail.com, therbert@google.com, xiaosuo@gmail.com, jesse@nicira.com, kees.cook@canonical.com, eugene@redhat.com, dan.j.rosenberg@gmail.com, akpm@linux-foundation.org Subject: [PATCH v2] net: don't allow CAP_NET_ADMIN to load non-netdev kernel modules Message-ID: <20110301213313.GA6507@albatros> References: <201102272122.52643.arnd@arndb.de> <4D6B6AE7.2050202@msgid.tls.msk.ru> <20110228095133.GA4351@albatros> <20110228.112349.104067277.davem@davemloft.net> <20110301194845.GA3533@albatros> <1299010390.2529.30.camel@bwh-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1299010390.2529.30.camel@bwh-desktop> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5189 Lines: 147 Since a8f80e8ff94ecba629542d9b4b5f5a8ee3eb565c any process with CAP_NET_ADMIN may load any module from /lib/modules/. This doesn't mean that CAP_NET_ADMIN is a superset of CAP_SYS_MODULE as modules are limited to /lib/modules/**. However, CAP_NET_ADMIN capability shouldn't allow anybody load any module not related to networking. This patch restricts an ability of autoloading modules to netdev modules with explicit aliases. This fixes CVE-2011-1019. Arnd Bergmann suggested to leave untouched the old pre-v2.6.32 behavior of loading netdev modules by name (without any prefix) for processes with CAP_SYS_MODULE to maintain the compatibility with network scripts that use autoloading netdev modules by aliases like "eth0", "wlan0". Currently there are only three users of the feature in the upstream kernel: ipip, ip_gre and sit. root@albatros:~# capsh --drop=$(seq -s, 0 11),$(seq -s, 13 34) -- root@albatros:~# grep Cap /proc/$$/status CapInh: 0000000000000000 CapPrm: fffffff800001000 CapEff: fffffff800001000 CapBnd: fffffff800001000 root@albatros:~# modprobe xfs FATAL: Error inserting xfs (/lib/modules/2.6.38-rc6-00001-g2bf4ca3/kernel/fs/xfs/xfs.ko): Operation not permitted root@albatros:~# lsmod | grep xfs root@albatros:~# ifconfig xfs xfs: error fetching interface information: Device not found root@albatros:~# lsmod | grep xfs root@albatros:~# lsmod | grep sit root@albatros:~# ifconfig sit sit: error fetching interface information: Device not found root@albatros:~# lsmod | grep sit root@albatros:~# ifconfig sit0 sit0 Link encap:IPv6-in-IPv4 NOARP MTU:1480 Metric:1 root@albatros:~# lsmod | grep sit sit 10457 0 tunnel4 2957 1 sit For CAP_SYS_MODULE module loading is still relaxed: root@albatros:~# grep Cap /proc/$$/status CapInh: 0000000000000000 CapPrm: ffffffffffffffff CapEff: ffffffffffffffff CapBnd: ffffffffffffffff root@albatros:~# ifconfig xfs xfs: error fetching interface information: Device not found root@albatros:~# lsmod | grep xfs xfs 745319 0 Reference: https://lkml.org/lkml/2011/2/24/203 Signed-off-by: Vasiliy Kulikov --- v2 - use pr_err() - don't try to load $name if netdev-$name is loaded include/linux/netdevice.h | 3 +++ net/core/dev.c | 12 ++++++++++-- net/ipv4/ip_gre.c | 2 +- net/ipv4/ipip.c | 2 +- net/ipv6/sit.c | 2 +- 5 files changed, 16 insertions(+), 5 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index d971346..71caf7a 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2392,6 +2392,9 @@ extern int netdev_notice(const struct net_device *dev, const char *format, ...) extern int netdev_info(const struct net_device *dev, const char *format, ...) __attribute__ ((format (printf, 2, 3))); +#define MODULE_ALIAS_NETDEV(device) \ + MODULE_ALIAS("netdev-" device) + #if defined(DEBUG) #define netdev_dbg(__dev, format, args...) \ netdev_printk(KERN_DEBUG, __dev, format, ##args) diff --git a/net/core/dev.c b/net/core/dev.c index 8ae6631..6561021 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1114,13 +1114,21 @@ EXPORT_SYMBOL(netdev_bonding_change); void dev_load(struct net *net, const char *name) { struct net_device *dev; + int no_module; rcu_read_lock(); dev = dev_get_by_name_rcu(net, name); rcu_read_unlock(); - if (!dev && capable(CAP_NET_ADMIN)) - request_module("%s", name); + no_module = !dev; + if (no_module && capable(CAP_NET_ADMIN)) + no_module = request_module("netdev-%s", name); + if (no_module && capable(CAP_SYS_MODULE)) { + if (!request_module("%s", name)) + pr_err("Loading kernel module for a network device " +"with CAP_SYS_MODULE (deprecated). Use CAP_NET_ADMIN and alias netdev-%s " +"instead\n", name); + } } EXPORT_SYMBOL(dev_load); diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index 6613edf..d1d0e2c 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -1765,4 +1765,4 @@ module_exit(ipgre_fini); MODULE_LICENSE("GPL"); MODULE_ALIAS_RTNL_LINK("gre"); MODULE_ALIAS_RTNL_LINK("gretap"); -MODULE_ALIAS("gre0"); +MODULE_ALIAS_NETDEV("gre0"); diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c index 988f52f..a5f58e7 100644 --- a/net/ipv4/ipip.c +++ b/net/ipv4/ipip.c @@ -913,4 +913,4 @@ static void __exit ipip_fini(void) module_init(ipip_init); module_exit(ipip_fini); MODULE_LICENSE("GPL"); -MODULE_ALIAS("tunl0"); +MODULE_ALIAS_NETDEV("tunl0"); diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c index 8ce38f1..d2c16e1 100644 --- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c @@ -1290,4 +1290,4 @@ static int __init sit_init(void) module_init(sit_init); module_exit(sit_cleanup); MODULE_LICENSE("GPL"); -MODULE_ALIAS("sit0"); +MODULE_ALIAS_NETDEV("sit0"); -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/