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authorVasiliy Kulikov <segoon@openwall.com>2011-03-02 00:33:13 +0300
committerGreg Kroah-Hartman <gregkh@suse.de>2011-03-14 14:30:00 -0700
commitaf4a02bb1eede764c1db87575462cbe1c023e164 (patch)
parent102123644979069c61d694375991aa6793e4da57 (diff)
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 <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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
5 files changed, 17 insertions, 3 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index ec12f8c24770..c27a18263d87 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2015,6 +2015,10 @@ static inline u32 dev_ethtool_get_flags(struct net_device *dev)
return 0;
return dev->ethtool_ops->get_flags(dev);
+#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 fd4c1e78154c..49e37821e13c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1037,13 +1037,21 @@ 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(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 143333852624..cfab9e419ef3 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -1708,3 +1708,4 @@ module_exit(ipgre_fini);
diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index ae40ed1ba560..f37df1a46a49 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -853,3 +853,4 @@ static void __exit ipip_fini(void)
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index dbd19a78ca73..de2ffefc7913 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -1101,4 +1101,4 @@ static int __init sit_init(void)