Commit Graph

13 Commits

Author SHA1 Message Date
Prasad J Pandit 3283dde4b5 qemu-bridge-helper: move repeating code in parse_acl_file
Move repeating error handling sequence in parse_acl_file routine
to an 'err' label.

Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
2019-07-29 16:29:30 +08:00
Prasad J Pandit 6f5d867122 qemu-bridge-helper: restrict interface name to IFNAMSIZ
The network interface name in Linux is defined to be of size
IFNAMSIZ(=16), including the terminating null('\0') byte.
The same is applied to interface names read from 'bridge.conf'
file to form ACL rules. If user supplied '--br=bridge' name
is not restricted to the same length, it could lead to ACL bypass
issue. Restrict interface name to IFNAMSIZ, including null byte.

Reported-by: Riccardo Schirone <rschiron@redhat.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
2019-07-29 16:29:30 +08:00
Markus Armbruster 436e353076 qemu-bridge-helper: Document known shortcomings
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
2019-07-02 10:21:06 +08:00
Markus Armbruster b8c3511d08 qemu-bridge-helper: Fix misuse of isspace()
parse_acl_file() passes char values to isspace().  Undefined behavior
when the value is negative.  Not a security issue, because the
characters come from trusted $prefix/etc/qemu/bridge.conf and the
files it includes.

Furthermore, isspace()'s locale-dependence means qemu-bridge-helper
uses the user's locale for parsing $prefix/etc/bridge.conf.  Feels
wrong.

Use g_ascii_isspace() instead.  This fixes the undefined behavior, and
makes parsing of $prefix/etc/bridge.conf locale-independent.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190514180311.16028-2-armbru@redhat.com>
2019-05-22 14:57:33 +02:00
Peter Maydell 030c98aff1 all: Remove unnecessary glib.h includes
Remove glib.h includes, as it is provided by osdep.h.

This commit was created with scripts/clean-includes.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
2016-06-07 18:19:24 +03:00
Peter Maydell d38ea87ac5 all: Clean up includes
Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.

This commit was created with scripts/clean-includes.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1454089805-5470-16-git-send-email-peter.maydell@linaro.org
2016-02-04 17:41:30 +00:00
Gonglei eb3f45c5af qemu-bridge-helper: Fix fd leak in main()
initialize fd and ctlfd, and close them at the end

Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-06-27 10:39:10 +02:00
Paolo Bonzini 226ecabfbd qemu-bridge-helper: force usage of a very high MAC address for the bridge
Linux uses the lowest enslaved MAC address as the MAC address of
the bridge.  Set MAC address to a high value so that it does not
affect the MAC address of the bridge.

Changing the MAC address of the bridge could cause a few seconds
of network downtime.

Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1363971468-21154-1-git-send-email-pbonzini@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2013-03-28 12:58:52 -05:00
Paolo Bonzini 1de7afc984 misc: move include files to include/qemu/
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-12-19 08:32:39 +01:00
Corey Bryant 34309d2b12 net: Add interface to bridge when SIOCBRADDIF isn't available
The bridge helper uses the SIOCBRADDIF ioctl to add an inteface to
a bridge.  SIOCBRADDIF is not available on old Linux versions.  This
patch adds support to use the SIOCDEVPRIVATE ioctl with BRCTL_ADD_IF
if SIOCBRADDIF is not available.

Reported-by: Fabien Chouteau <chouteau@adacore.com>
Signed-off-by: Corey Bryant <coreyb@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2012-08-01 12:28:51 +01:00
Corey Bryant 47e98658f5 Add cap reduction support to enable use as SUID
The ideal way to use qemu-bridge-helper is to give it an fscap of using:

 setcap cap_net_admin=ep qemu-bridge-helper

Unfortunately, most distros still do not have a mechanism to package files
with fscaps applied.  This means they'll have to SUID the qemu-bridge-helper
binary.

To improve security, use libcap to reduce our capability set to just
cap_net_admin, then reduce privileges down to the calling user.  This is
hopefully close to equivalent to fscap support from a security perspective.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Richa Marwaha <rmarwah@linux.vnet.ibm.com>
Signed-off-by: Corey Bryant <coreyb@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2012-02-01 16:24:39 -06:00
Corey Bryant bdef79a299 Add access control support to qemu bridge helper
We go to great lengths to restrict ourselves to just cap_net_admin as an OS
enforced security mechanism.  However, we further restrict what we allow users
to do to simply adding a tap device to a bridge interface by virtue of the fact
that this is the only functionality we expose.

This is not good enough though.  An administrator is likely to want to restrict
the bridges that an unprivileged user can access, in particular, to restrict
an unprivileged user from putting a guest on what should be isolated networks.

This patch implements an ACL mechanism that is enforced by qemu-bridge-helper.
The ACLs are fairly simple whitelist/blacklist mechanisms with a wildcard of
'all'.  All users are blacklisted by default, and deny takes precedence over
allow.

An interesting feature of this ACL mechanism is that you can include external
ACL files.  The main reason to support this is so that you can set different
file system permissions on those external ACL files.  This allows an
administrator to implement rather sophisticated ACL policies based on
user/group policies via the file system.

As an example:

/etc/qemu/bridge.conf root:qemu 0640

 allow br0
 include /etc/qemu/alice.conf
 include /etc/qemu/bob.conf
 include /etc/qemu/charlie.conf

/etc/qemu/alice.conf root:alice 0640
 allow br1

/etc/qemu/bob.conf root:bob 0640
 allow br2

/etc/qemu/charlie.conf root:charlie 0640
 deny all

This ACL pattern allows any user in the qemu group to get a tap device
connected to br0 (which is bridged to the physical network).

Users in the alice group can additionally get a tap device connected to br1.
This allows br1 to act as a private bridge for the alice group.

Users in the bob group can additionally get a tap device connected to br2.
This allows br2 to act as a private bridge for the bob group.

Users in the charlie group cannot get a tap device connected to any bridge.

Under no circumstance can the bob group get access to br1 or can the alice
group get access to br2.  And under no cicumstance can the charlie group
get access to any bridge.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Richa Marwaha <rmarwah@linux.vnet.ibm.com>
Signed-off-by: Corey Bryant <coreyb@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2012-02-01 16:24:39 -06:00
Corey Bryant 7b93fadf3a Add basic version of bridge helper
This patch adds a helper that can be used to create a tap device attached to
a bridge device.  Since this helper is minimal in what it does, it can be
given CAP_NET_ADMIN which allows qemu to avoid running as root while still
satisfying the majority of what users tend to want to do with tap devices.

The way this all works is that qemu launches this helper passing a bridge
name and the name of an inherited file descriptor.  The descriptor is one
end of a socketpair() of domain sockets.  This domain socket is used to
transmit a file descriptor of the opened tap device from the helper to qemu.

The helper can then exit and let qemu use the tap device.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Richa Marwaha <rmarwah@linux.vnet.ibm.com>
Signed-off-by: Corey Bryant <coreyb@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2012-02-01 16:24:38 -06:00