From 764504f33c9f5d2692dac5873c2bbbc7363b525c Mon Sep 17 00:00:00 2001 From: Vasiliy Kulikov Date: Wed, 2 Mar 2011 00:33:13 +0300 Subject: [PATCH] net: don't allow CAP_NET_ADMIN to load non-netdev kernel modules 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 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: Greg Kroah-Hartman Signed-off-by: Andi Kleen --- include/linux/netdevice.h | 4 ++++ net/core/dev.c | 13 ++++++++++--- net/ipv4/ip_gre.c | 1 + net/ipv4/ipip.c | 1 + net/ipv6/sit.c | 2 +- 5 files changed, 17 insertions(+), 4 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 142bf182caa89..e857c94559344 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2344,6 +2344,10 @@ do { \ }) #endif +#define MODULE_ALIAS_NETDEV(device) \ + MODULE_ALIAS("netdev-" device) + + #endif /* __KERNEL__ */ #endif /* _LINUX_NETDEVICE_H */ diff --git a/net/core/dev.c b/net/core/dev.c index d7d352ba56cda..7c3e7c36c0b79 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1121,13 +1121,20 @@ 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 32618e11076d4..cd527c4407084 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -1701,3 +1701,4 @@ 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 7fd636711037a..5d8e362b2383d 100644 --- a/net/ipv4/ipip.c +++ b/net/ipv4/ipip.c @@ -850,3 +850,4 @@ 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 e51e650ea80be..2020bea68952c 100644 --- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c @@ -1239,4 +1239,4 @@ static int __init sit_init(void) module_init(sit_init); module_exit(sit_cleanup); MODULE_LICENSE("GPL"); -MODULE_ALIAS("sit0"); +MODULE_ALIAS_NETDEV("sit0"); -- 2.47.2