From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933732Ab1DNSB0 (ORCPT ); Thu, 14 Apr 2011 14:01:26 -0400 Received: from mail.windriver.com ([147.11.1.11]:42515 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933403Ab1DNR7o (ORCPT ); Thu, 14 Apr 2011 13:59:44 -0400 From: Paul Gortmaker To: stable@kernel.org, linux-kernel@vger.kernel.org Cc: stable-review@kernel.org, Vasiliy Kulikov , Michael Tokarev , James Morris , Paul Gortmaker Subject: [34-longterm 200/209] net: don't allow CAP_NET_ADMIN to load non-netdev kernel modules Date: Thu, 14 Apr 2011 13:55:58 -0400 Message-Id: <1302803767-9715-87-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.7.4.4 In-Reply-To: <1302803767-9715-1-git-send-email-paul.gortmaker@windriver.com> References: <1302803039-9400-1-git-send-email-paul.gortmaker@windriver.com> <1302803767-9715-1-git-send-email-paul.gortmaker@windriver.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Vasiliy Kulikov ===================================================================== | This is a commit scheduled for the next v2.6.34 longterm release. | | If you see a problem with using this for longterm, please comment.| ===================================================================== commit 8909c9ad8ff03611c9c96c9a92656213e4bb495b upstream. 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 [PG: in 2.6.34, the bare MODULE_ALIAS for ipip/tunl0 and ip_gre/gre0 didn't exist, but this adds the limited scope MODULE_ALIAS_NETDEV ones] Signed-off-by: Vasiliy Kulikov Signed-off-by: Michael Tokarev Acked-by: David S. Miller Acked-by: Kees Cook Signed-off-by: James Morris Signed-off-by: Paul Gortmaker --- include/linux/netdevice.h | 3 +++ net/core/dev.c | 12 ++++++++++-- net/ipv4/ip_gre.c | 1 + net/ipv4/ipip.c | 1 + net/ipv6/sit.c | 2 +- 5 files changed, 16 insertions(+), 3 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 4737996..0af14f2 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2214,6 +2214,9 @@ do { \ #define netif_info(priv, type, dev, fmt, args...) \ netif_printk(priv, type, KERN_INFO, (dev), fmt, ##args) +#define MODULE_ALIAS_NETDEV(device) \ + MODULE_ALIAS("netdev-" device) + #if defined(DEBUG) #define netif_dbg(priv, type, dev, format, args...) \ netif_printk(priv, type, KERN_DEBUG, dev, format, ##args) diff --git a/net/core/dev.c b/net/core/dev.c index f664177..3095934 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1104,13 +1104,21 @@ 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 fe381d1..6be6fe7 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -1709,3 +1709,4 @@ module_exit(ipgre_fini); MODULE_LICENSE("GPL"); MODULE_ALIAS_RTNL_LINK("gre"); MODULE_ALIAS_RTNL_LINK("gretap"); +MODULE_ALIAS_NETDEV("gre0"); diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c index 0b27b14..8900fde 100644 --- a/net/ipv4/ipip.c +++ b/net/ipv4/ipip.c @@ -853,3 +853,4 @@ static void __exit ipip_fini(void) module_init(ipip_init); module_exit(ipip_fini); MODULE_LICENSE("GPL"); +MODULE_ALIAS_NETDEV("tunl0"); diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c index 5abae10..5316ce5 100644 --- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c @@ -1241,4 +1241,4 @@ static int __init sit_init(void) module_init(sit_init); module_exit(sit_cleanup); MODULE_LICENSE("GPL"); -MODULE_ALIAS("sit0"); +MODULE_ALIAS_NETDEV("sit0"); -- 1.7.4.4