diff options
authorVasiliy Kulikov <segoon@openwall.com>2011-03-02 00:33:13 +0300
committerJames Morris <jmorris@namei.org>2011-03-10 10:25:19 +1100
commit8909c9ad8ff03611c9c96c9a92656213e4bb495b (patch)
parenta5abba989deceb731047425812d268daf7536575 (diff)
net: don't allow CAP_NET_ADMIN to load non-netdev kernel modules
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 <segoon@openwall.com> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Kees Cook <kees.cook@canonical.com> Signed-off-by: James Morris <jmorris@namei.org>
5 files changed, 16 insertions, 5 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index d971346b034..71caf7a5e6c 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 8ae6631abcc..6561021d22d 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;
dev = dev_get_by_name_rcu(net, name);
- 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);
+ }
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 6613edfac28..d1d0e2c256f 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -1765,4 +1765,4 @@ module_exit(ipgre_fini);
diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index 988f52fba54..a5f58e7cbb2 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -913,4 +913,4 @@ static void __exit ipip_fini(void)
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 8ce38f10a54..d2c16e10f65 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -1290,4 +1290,4 @@ static int __init sit_init(void)