def _validatePath(path, perms):
"""Validate a disk image or other ifle.
_validatePath makes sure that the user requesting a privileged
operation would have permission to interact with the file in
question.
Args:
disk: A path to a disk image
perms: A bitmask composed of os.R_OK, os.W_OK, and/or os.X_OK
Raises:
debmarshal.errors.AccessDenied if the unprivileged user doesn't
have permission to interact with the path using perms.
"""
# Start by setting the process uid to getCaller(). This is primarily
# done to make sure we're respecting the abstraction introduced by
# getCaller().
#
# This won't guarantee that we have the necessary bits for, e.g.,
# AFS, where you need a separate token to prove your identity, but
# it would work for most other cases.
old_uid = os.getuid()
os.setreuid(utils.getCaller(), 0)
try:
if not os.access(path, perms):
raise errors.AccessDenied('UID %s does not have access to %s.' %
(utils.getCaller(), path))
finally:
# Reset the process uid that we changed earlier.
os.setuid(old_uid)
def _validateNetwork(net, virt_con=None):
"""Validate a debmarshal network.
This function checks that the network name passed in is a network
known to (i.e. created by) debmarshal. It also verifies that the
network was created by the user calling the function.
Args:
net: The name of the debmarshal network.
virt_con: A read-only libvirt.virConnect instance. We'll open one
of our own if one isn't passed in. Since libvirt network
information is shared across all hypervisors, virt_con can be a
connection to any libvirt driver.
Raises:
debmarshal.errors.NetworkNotFound if the named network doesn't
exist.
debmarshal.errors.AccessDenied if the network isn't owned by the
caller.
"""
if not virt_con:
virt_con = libvirt.open('qemu:///system')
nets = networks.loadNetworkState(virt_con)
if net not in nets:
raise errors.NetworkNotFound("Network %s does not exist." % net)
if nets[net] != utils.getCaller():
raise errors.AccessDenied("Network %s is not owned by UID %s." %
(net, utils.getCaller()))
def testWrongUser(self):
"""Wrong user leads to an AcccessDenied exception."""
self.mox.StubOutWithMock(utils, 'getCaller')
utils.getCaller().MultipleTimes().AndReturn(500)
self.mox.ReplayAll()
self.assertRaises(errors.AccessDenied, domains._validateNetwork,
'debmarshal-1', self.virt_con)
def testValidNetwork(self):
"""Valid network name from the right caller passes validation."""
self.mox.StubOutWithMock(utils, 'getCaller')
utils.getCaller().MultipleTimes().AndReturn(500)
self.mox.ReplayAll()
# Once again, we want a self.assertNoRaises, or something, but it
# doesn't exist, so we just run the code
domains._validateNetwork('debmarshal-0', self.virt_con)
def testNoConnection(self):
"""_validateNetwork is able to open its own libvirt connection."""
self.mox.StubOutWithMock(libvirt, 'open')
libvirt.open(mox.IgnoreArg()).AndReturn(self.virt_con)
self.mox.StubOutWithMock(utils, 'getCaller')
utils.getCaller().MultipleTimes().AndReturn(500)
self.mox.ReplayAll()
domains._validateNetwork('debmarshal-0')
def setUp(self):
"""Setup the getuid/setuid dance."""
super(TestValidatePath, self).setUp()
self.mox.StubOutWithMock(os, 'getuid')
self.mox.StubOutWithMock(os, 'setreuid')
self.mox.StubOutWithMock(os, 'setuid')
self.mox.StubOutWithMock(utils, 'getCaller')
os.getuid().MultipleTimes().AndReturn(0)
utils.getCaller().MultipleTimes().AndReturn(500)
os.setreuid(500, 0)
os.setuid(0)