linux.git/net/ipv4/ip_gre.c, branch v2.6.38

net: don't allow CAP_NET_ADMIN to load non-netdev kernel modules

2011-03-09T23:25:19+00:00

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

ip_gre: Add IPPROTO_GRE to flowi in ipgre_tunnel_xmit

2011-02-11T19:23:12+00:00

Commit 5811662b15db018c740c57d037523683fd3e6123 ("net: use the macros
defined for the members of flowi") accidentally removed the setting of
IPPROTO_GRE from the struct flowi in ipgre_tunnel_xmit. This patch
restores it.

Signed-off-by: Steffen Klassert 
Acked-by: Changli Gao 
Signed-off-by: David S. Miller

ipv4: Don't pre-seed hoplimit metric.

2010-12-13T06:08:17+00:00

Always go through a new ip4_dst_hoplimit() helper, just like ipv6.

This allowed several simplifications:

1) The interim dst_metric_hoplimit() can go as it's no longer
   userd.

2) The sysctl_ip_default_ttl entry no longer needs to use
   ipv4_doint_and_flush, since the sysctl is not cached in
   routing cache metrics any longer.

3) ipv4_doint_and_flush no longer needs to be exported and
   therefore can be marked static.

When ipv4_doint_and_flush_strategy was removed some time ago,
the external declaration in ip.h was mistakenly left around
so kill that off too.

We have to move the sysctl_ip_default_ttl declaration into
ipv4's route cache definition header net/route.h, because
currently net/ip.h (where the declaration lives now) has
a back dependency on net/route.h

Signed-off-by: David S. Miller

net: Abstract RTAX_HOPLIMIT metric accesses behind helper.

2010-12-13T05:35:57+00:00

Signed-off-by: David S. Miller

net: Abstract away all dst_entry metrics accesses.

2010-12-09T18:46:36+00:00

Use helper functions to hide all direct accesses, especially writes,
to dst_entry metrics values.

This will allow us to:

1) More easily change how the metrics are stored.

2) Implement COW for metrics.

In particular this will help us put metrics into the inetpeer
cache if that is what we end up doing.  We can make the _metrics
member a pointer instead of an array, initially have it point
at the read-only metrics in the FIB, and then on the first set
grab an inetpeer entry and point the _metrics member there.

Signed-off-by: David S. Miller 
Acked-by: Eric Dumazet

gre: add module alias for gre0 tunnel device

2010-12-01T20:53:22+00:00

If gre is built as a module the 'ip tunnel add' command would fail because
the ip_gre module was not being autoloaded.  Adding an alias for
the gre0 device name cause dev_load() to autoload it when needed.

Signed-off-by: Stephen Hemminger 
Signed-off-by: David S. Miller

gre: minor cleanups

2010-12-01T20:53:22+00:00

Use strcpy() rather the sprintf() for the case where name is getting
generated.  Fix indentation.

Signed-off-by: Stephen Hemminger 
Signed-off-by: David S. Miller

net: use the macros defined for the members of flowi

2010-11-17T20:27:45+00:00

Use the macros defined for the members of flowi to clean the code up.

Signed-off-by: Changli Gao 
Signed-off-by: David S. Miller

xfrm: use gre key as flow upper protocol info

2010-11-15T18:44:04+00:00

The GRE Key field is intended to be used for identifying an individual
traffic flow within a tunnel. It is useful to be able to have XFRM
policy selector matches to have different policies for different
GRE tunnels.

Signed-off-by: Timo Teräs 
Signed-off-by: David S. Miller

ipv4: Make rt->fl.iif tests lest obscure.

2010-11-12T01:07:48+00:00

When we test rt->fl.iif against zero, we're seeing if it's
an output or an input route.

Make that explicit with some helper functions.

Signed-off-by: David S. Miller