With my previous patches, we unconditionally appended a seclabel,
even if it wasn't generated but found in array of defined seclabels.
This resulted in double free later when doing virDomainDefFree
and iterating over the array of defined seclabels.
Moreover, there was another possibility of double free, if the
seclabel was generated in the last iteration of the process of
walking trough security managers array.
https://bugzilla.redhat.com/show_bug.cgi?id=923946
The <seclabel type='none'/> should be added iff there is no other
seclabel defined within a domain. This bug can be easily reproduced:
1) configure selinux seclabel for a domain
2) disable system's selinux and restart libvirtd
3) observe <seclabel type='none'/> being appended to a domain on its
startup
The virDomainDefGetSecurityLabelDef was modifying the domain XML.
It tried to find a seclabel corresponding to given sec driver. If the
label wasn't found, the function created one which is wrong. In fact
it's security manager which should modify this part of domain XML.
Normally libvirtd should run with a SELinux label
system_u:system_r:virtd_t:s0-s0:c0.c1023
If a user manually runs libvirtd though, it is sometimes
possible to get into a situation where it is running
system_u:system_r:init_t:s0
The SELinux security driver isn't expecting this and can't
parse the security label since it lacks the ':c0.c1023' part
causing it to complain
internal error Cannot parse sensitivity level in s0
This updates the parser to cope with this, so if no category
is present, libvirtd will hardcode the equivalent of c0.c1023.
Now this won't work if SELinux is in Enforcing mode, but that's
not an issue, because the user can only get into this problem
if in Permissive mode. This means they can now start VMs in
Permissive mode without hitting that parsing error
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Pull the code which parses the current process MCS range
out of virSecuritySELinuxMCSFind and into a new method
virSecuritySELinuxMCSGetProcessRange.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
The body of the loop in virSecuritySELinuxMCSFind would
directly 'return NULL' on OOM, instead of jumping to the
cleanup label. This caused a leak of several local vars.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
The virCaps structure gathered a ton of irrelevant data over time that.
The original reason is that it was propagated to the XML parser
functions.
This patch aims to create a new data structure virDomainXMLConf that
will contain immutable data that are used by the XML parser. This will
allow two things we need:
1) Get rid of the stuff from virCaps
2) Allow us to add callbacks to check and add driver specific stuff
after domain XML is parsed.
This first attempt removes pointers to private data allocation functions
to this new structure and update all callers and function that require
them.
Rename AppArmorSetImageFDLabel to AppArmorSetFDLabel which could
be used as a common function for *ALL* fd relabelling in Linux.
In apparmor profile for specific vm with uuid cdbebdfa-1d6d-65c3-be0f-fd74b978a773
Path: /etc/apparmor.d/libvirt/libvirt-cdbebdfa-1d6d-65c3-be0f-fd74b978a773.files
The last line is for the tapfd relabelling.
# DO NOT EDIT THIS FILE DIRECTLY. IT IS MANAGED BY LIBVIRT.
"/var/log/libvirt/**/rhel6qcow2.log" w,
"/var/lib/libvirt/**/rhel6qcow2.monitor" rw,
"/var/run/libvirt/**/rhel6qcow2.pid" rwk,
"/run/libvirt/**/rhel6qcow2.pid" rwk,
"/var/run/libvirt/**/*.tunnelmigrate.dest.rhel6qcow2" rw,
"/run/libvirt/**/*.tunnelmigrate.dest.rhel6qcow2" rw,
"/var/lib/libvirt/images/rhel6u3qcow2.img" rw,
"/dev/tap45" rw,
With the apparmor security driver enabled, qemu instances fail
to start
# grep ^security_driver /etc/libvirt/qemu.conf
security_driver = "apparmor"
# virsh start test-kvm
error: Failed to start domain test-kvm
error: internal error security label already defined for VM
The model field of virSecurityLabelDef object is always populated
by virDomainDefGetSecurityLabelDef(), so remove the check for a
NULL model when verifying if a label is already defined for the
instance.
Checking for a NULL model and populating it later in
AppArmorGenSecurityLabel() has been left in the code to be
consistent with virSecuritySELinuxGenSecurityLabel().
Coverity found the DACGenLabel was checking for mgr == NULL after a
possible dereference; however, in order to get into the function the
virSecurityManagerGenLabel would have already dereferenced sec_managers[i]
so the check was unnecessary. Same check is made in SELinuxGenSecurityLabel.
The existing virSecurityManagerSetProcessLabel() API is designed so
that it must be called after forking the child process, but before
exec'ing the child. Due to the way the virCommand API works, that
means it needs to be put in a "hook" function that virCommand is told
to call out to at that time.
Setting the child process label is a basic enough need when executing
any process that virCommand should have a method of doing that. But
virCommand must be told what label to set, and only the security
driver knows the answer to that question.
The new virSecurityManagerSet*Child*ProcessLabel() API is the way to
transfer the knowledge about what label to set from the security
driver to the virCommand object. It is given a virCommandPtr, and each
security driver calls the appropriate virCommand* API to tell
virCommand what to do between fork and exec.
1) in the case of the DAC security driver, it calls
virCommandSetUID/GID() to set a uid and gid that must be set for the
child process.
2) for the SELinux security driver, it calls
virCommandSetSELinuxLabel() to save a copy of the char* that will be
sent to setexeccon_raw() *after forking the child process*.
3) for the AppArmor security drivers, it calls
virCommandSetAppArmorProfile() to save a copy of the char* that will
be sent to aa_change_profile() *after forking the child process*.
With this new API in place, we will be able to remove
virSecurityManagerSetProcessLabel() from any virCommand pre-exec
hooks.
(Unfortunately, the LXC driver uses clone() rather than virCommand, so
it can't take advantage of this new security driver API, meaning that
we need to keep around the older virSecurityManagerSetProcessLabel(),
at least for now.)
The hook scripts used by virCommand must be careful wrt
accessing any mutexes that may have been held by other
threads in the parent process. With the recent refactoring
there are 2 potential flaws lurking, which will become real
deadlock bugs once the global QEMU driver lock is removed.
Remove use of the QEMU driver lock from the hook function
by passing in the 'virQEMUDriverConfigPtr' instance directly.
Add functions to the virSecurityManager to be invoked before
and after fork, to ensure the mutex is held by the current
thread. This allows it to be safely used in the hook script
in the child process.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
On RHEL 5, I got:
security/security_selinux.c: In function 'getContext':
security/security_selinux.c:971: warning: unused parameter 'mgr' [-Wunused-parameter]
* src/security/security_selinux.c (getContext): Mark potentially
unused parameter.
The security manager drivers are not allowed to call back
out to top level security manager APIs, since that results
in recursive mutex acquisition and thus deadlock. Remove
calls to virSecurityManagerGetModel from SELinux / AppArmor
drivers
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Add locking to virSecurityManagerXXX APIs, so that use of the
security drivers is internally serialized. This avoids the need
to rely on the global driver locks to achieve serialization
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
To enable locking to be introduced to the security manager
objects later, turn virSecurityManager into a virObjectLockable
class
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
To enable virCapabilities instances to be reference counted,
turn it into a virObject. All cases of virCapabilitiesFree
turn into virObjectUnref
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Commit id a994ef2d1 changed the mechanism to store/update the default
security label from using disk->seclabels[0] to allocating one on the
fly. That change allocated the label, but never saved it. This patch
will save the label. The new virDomainDiskDefAddSecurityLabelDef() is
a copy of the virDomainDefAddSecurityLabelDef().
When changing to virArch, the virt-aa-helper.c file was not
completely changed. The vahControl struct was left with a
char *arch field, instead of virArch arch field.
Convert the host capabilities and domain config structs to
use the virArch datatype. Update the parsers and all drivers
to take account of datatype change
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Prepare to support different types of hostdevs by refactoring
the current SELinux security driver code
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
When LXC labels USB devices during hotplug, it is running in
host context, so it needs to pass in a vroot path to the
container root.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
The virSecurityManager{Set,Restore}AllLabel methods are invoked
at domain startup/shutdown to relabel resources associated with
a domain. This works fine with QEMU, but with LXC they are in
fact both currently no-ops since LXC does not support disks,
hostdevs, or kernel/initrd files. Worse, when LXC gains support
for disks/hostdevs, they will do the wrong thing, since they
run in host context, not container context. Thus this patch
turns then into a formal no-op when used with LXC. The LXC
controller will call out to specific security manager labelling
APIs as required during startup.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
The current SELinux policy only works for KVM guests, since
TCG requires the 'execmem' privilege. There is a 'virt_use_execmem'
boolean to turn this on globally, but that is unpleasant for users.
This changes libvirt to automatically use a new 'svirt_tcg_t'
context for TCG based guests. This obsoletes the previous
boolean tunable and makes things 'just work(tm)'
Since we can't assume we run with new enough policy, I also
make us log a warning message (once only) if we find the policy
lacks support. In this case we fallback to the normal label and
expect users to set the boolean tunable
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
When using vnc gaphics over a unix socket, virt-aa-helper needs to provide
access for the qemu domain to access the sockfile.
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
