The VIR_SECURITY_MANAGER_MOUNT_NAMESPACE flag informs the DAC driver
if mount namespaces are in use for the VM. Will be used for future
changes.
Wire it up in the qemu driver
Our commit e13e8808f9 was way too generic. Currently, virtlogd is
used only for chardevs type of file and nothing else. True, we
must not relabel the path in this case, but we have to in all
other cases. For instance, if you want to have a physical console
attached to your guest:
<console type='dev'>
<source path='/dev/ttyS0'/>
<target type='virtio' port='1'/>
</console>
Starting such domain fails because qemu doesn't have access to
/dev/ttyS0 because we haven't relabelled the path.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>
In the case that virtlogd is used as stdio handler we pass to QEMU
only FD to a PIPE connected to virtlogd instead of the file itself.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1430988
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
Namely, this patch is about virMediatedDeviceGetIOMMUGroup{Dev,Num}
functions. There's no compelling reason why these functions should take
an object, on the contrary, having to create an object every time one
needs to query the IOMMU group number, discarding the object afterwards,
seems odd.
Signed-off-by: Erik Skultety <eskultet@redhat.com>
This patch updates all of our security driver to start labeling the
VFIO IOMMU devices under /dev/vfio/ as well.
Signed-off-by: Erik Skultety <eskultet@redhat.com>
A mediated device will be identified by a UUID (with 'model' now being
a mandatory <hostdev> attribute to represent the mediated device API) of
the user pre-created mediated device. We also need to make sure that if
user explicitly provides a guest address for a mdev device, the address
type will be matching the device API supported on that specific mediated
device and error out with an incorrect XML message.
The resulting device XML:
<devices>
<hostdev mode='subsystem' type='mdev' model='vfio-pci'>
<source>
<address uuid='c2177883-f1bb-47f0-914d-32a22e3a8804'>
</source>
</hostdev>
</devices>
Signed-off-by: Erik Skultety <eskultet@redhat.com>
When domain is being started up, we ought to relabel the host
side of NVDIMM so qemu has access to it.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
The problem is in the way how the list item is created prior to
appending it to the transaction list - the @path attribute is just a
shallow copy instead of deep copy of the hostdev device's path.
Unfortunately, the hostdev devices from which the @path is extracted, in
order to add them into the transaction list, are only temporary and
freed before the buildup of the qemu namespace, thus making the @path
attribute in the transaction list NULL, causing 'permission denied' or
'double free' or 'unknown cause' errors.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1413773
Signed-off-by: Erik Skultety <eskultet@redhat.com>
The code at the very bottom of the DAC secdriver that calls
chown() should be fine with read-only data. If something needs to
be prepared it should have been done beforehand.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
We already have a "scsi" hostdev subsys type, which refers to a single
LUN that is passed through to a guest. But what of things where
multiple LUNs are passed through via a single SCSI HBA, such as with
the vhost-scsi target? Create a new hostdev subsys type that will
carry this.
Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>
Change the virDomainChrDef to use a pointer to 'source' and allocate
that pointer during virDomainChrDefNew.
This has tremendous "fallout" in the rest of the code which mainly
has to change source.$field to source->$field.
Signed-off-by: John Ferlan <jferlan@redhat.com>
A device tree binary file specified by /domain/os/dtb element is a
read-only resource similar to kernel and initrd files. We shouldn't
restore its label when destroying a domain to avoid breaking other
domains configure with the same device tree.
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Kernel/initrd files are essentially read-only shareable images and thus
should be handled in the same way. We already use the appropriate label
for kernel/initrd files when starting a domain, but when a domain gets
destroyed we would remove the labels which would make other running
domains using the same files very unhappy.
https://bugzilla.redhat.com/show_bug.cgi?id=921135
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Many of the functions follow the pattern:
virSecurity.*Security.*Label
Remove the second 'Security' from the names, it should be obvious
that the virSecurity* functions deal with security labels even
without it.
Fixes several style issues and removes "DEF" (what is it supposed to
mean anyway?) from debug messages.
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Even though the APIs are not implemented yet, they create a
skeleton that can be filled in later.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
This function should really be called only when we want to change
ownership of a file (or disk source). Lets switch to calling a
wrapper function which will eventually record the current owner
of the file and call virSecurityDACSetOwnershipInternal
subsequently.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
This is pure code adjustment. The structure is going to be needed
later as it will hold a reference that will be used to talk to
virtlockd. However, so far this is no functional change just code
preparation.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
This is pure code adjustment. The structure is going to be needed
later as it will hold a reference that will be used to talk to
virtlockd. However, so far this is no functional change just code
preparation.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
It's better if we stat() file that we are about to chown() at
first and check if there's something we need to change. Not that
it would make much difference, but for the upcoming patches we
need to be doing stat() anyway. Moreover, if we do things this
way, we can drop @chown_errno variable which will become
redundant.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Correctly mark the places where we need to remember and recall
file ownership. We don't want to mislead any potential developer.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
SELinux security driver already does that, but DAC driver somehow missed
the memo. Let's fix it so it works the same way.
Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
When using qemuProcessAttach to attach a qemu process,
the DAC label is not filled correctly.
Introduce a new function to get the uid:gid from the system
and fill the label.
This fixes the daemon crash when 'virsh screenshot' is called:
https://bugzilla.redhat.com/show_bug.cgi?id=1161831
It also fixes qemu-attach after the prerequisite of this patch
(commit f8c1fb3) was pushed out of order.
Signed-off-by: Luyao Huang <lhuang@redhat.com>
Signed-off-by: Ján Tomko <jtomko@redhat.com>
The check for ISCSI devices was missing a check of subsys type, which
meant we could skip labelling of other host devices as well. This fixes
USB hotplug on F21
https://bugzilla.redhat.com/show_bug.cgi?id=1145968
QEMU now supports UEFI with the following command line:
-drive file=/usr/share/OVMF/OVMF_CODE.fd,if=pflash,format=raw,unit=0,readonly=on \
-drive file=/usr/share/OVMF/OVMF_VARS.fd,if=pflash,format=raw,unit=1 \
where the first line reflects <loader> and the second one <nvram>.
Moreover, these two lines obsolete the -bios argument.
Note that UEFI is unusable without ACPI. This is handled properly now.
Among with this extension, the variable file is expected to be
writable and hence we need security drivers to label it.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Create the structures and API's to hold and manage the iSCSI host device.
This extends the 'scsi_host' definitions added in commit id '5c811dce'.
A future patch will add the XML parsing, but that code requires some
infrastructure to be in place first in order to handle the differences
between a 'scsi_host' and an 'iSCSI host' device.
Split virDomainHostdevSubsysSCSI further. In preparation for having
either SCSI or iSCSI data, create a union in virDomainHostdevSubsysSCSI
to contain just a virDomainHostdevSubsysSCSIHost to describe the
'scsi_host' host device
To integrate the security driver with the storage driver we need to
pass a callback for a function that will chown storage volumes.
Introduce and document the callback prototype.
When restoring security labels in the dac driver the code would resolve
the file path and use the resolved one to be chown-ed. The setting code
doesn't do that. Remove the unnecessary code.
This negation in names of boolean variables is driving me insane. The
code is much more readable if we drop the 'no-' prefix. Well, at least
for me.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
In the future we might need to track state of individual images. Move
the readonly and shared flags to the virStorageSource struct so that we
can keep them in a per-image basis.
I'm going to add functions that will deal with individual image files
rather than whole disks. Rename the security function to make room for
the new one.
I'm going to add functions that will deal with individual image files
rather than whole disks. Rename the security function to make room for
the new one.
The image labels are stored in the virStorageSource struct. Convert the
virDomainDiskDefGetSecurityLabelDef helper not to use the full disk def
and move it appropriately.
A network disk might actually be backed by local storage. Also the path
iterator actually handles networked disks well now so remove the code
that skips the labelling in dac and selinux security driver.
In "src/conf/domain_conf.h" there are many enum declarations. The
cleanup in this header filer was started, but it wasn't enough and
there are many other files that has enum variables declared. So, the
commit was starting to be big. This commit finish the cleanup in this
header file and in other files that has enum variables, parameters,
or functions declared.
Signed-off-by: Julio Faracco <jcfaracco@gmail.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
In "src/conf/domain_conf.h" there are many enumerations (enum)
declarations to be converted as a typedef too. As mentioned before,
it's better to use a typedef for variable types, function types and
other usages. I think this file has most of those enum declarations
at "src/conf/". So, me and Eric Blake plan to keep the cleanups all
over the source code. This time, most of the files changed in this
commit are related to part of one file: "src/conf/domain_conf.h".
Signed-off-by: Julio Faracco <jcfaracco@gmail.com>
With dynamic_ownership = 1 but no seclabels, RestoreChardevLabel
dereferences the NULL seclabel when checking if norelabel is set.
Remove this check, since it is already done in RestoreSecurityAllLabel
and if norelabel is set, RestoreChardevLabel is never called.
The domain definition is clearly used a few lines
below so there's no need to mark @def as unused.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
The DAC driver ignores the relabel='no' attribute in chardev config
<serial type='file'>
<source path='/tmp/jim/test.file'>
<seclabel model='dac' relabel='no'/>
</source>
<target port='0'/>
</serial>
This patch avoids labeling chardevs when relabel='no' is specified.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
When relabel='no' at the domain level, there is no need to call
the hostdev relabeling functions.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
https://bugzilla.redhat.com/show_bug.cgi?id=999301
The DAC driver ignores the relabel='no' attribute in disk config
<disk type='file' device='floppy'>
<driver name='qemu' type='raw'/>
<source file='/some/path/floppy.img'>
<seclabel model='dac' relabel='no'/>
</source>
<target dev='fda' bus='fdc'/>
<readonly/>
</disk>
This patch avoid labeling disks when relabel='no' is specified.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
If relabel='no' at the domain level, no need to attempt relabeling
in virSecurityDAC{Set,Restore}SecurityAllLabel().
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Currently, the DAC security driver passes callback data as
void params[2];
params[0] = mgr;
params[1] = def;
Clean this up by defining a structure for passing the callback
data. Moreover, there's no need to pass the whole virDomainDef
in the callback as the only thing needed in the callbacks is
virSecurityLabelDefPtr.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
In switch statements, use enum types since it is safer when
adding new items to the enum.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Annotate some static function parameters with ATTRIBUTE_NONNULL
and remove checks for NULL inputs.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
The code in virstoragefile.c is getting more complex as I
consolidate backing chain handling code. But for the setuid
virt-login-shell, we don't need to crawl backing chains. It's
easier to audit things for setuid security if there are fewer
files involved, so this patch moves the one function that
virFileOpen() was actually relying on to also live in virfile.c.
* src/util/virstoragefile.c (virStorageFileIsSharedFS)
(virStorageFileIsSharedFSType): Move...
* src/util/virfile.c (virFileIsSharedFS, virFileIsSharedFSType):
...to here, and rename.
(virFileOpenAs): Update caller.
* src/security/security_selinux.c
(virSecuritySELinuxSetFileconHelper)
(virSecuritySELinuxSetSecurityAllLabel)
(virSecuritySELinuxRestoreSecurityImageLabelInt): Likewise.
* src/security/security_dac.c
(virSecurityDACRestoreSecurityImageLabelInt): Likewise.
* src/qemu/qemu_driver.c (qemuOpenFileAs): Likewise.
* src/qemu/qemu_migration.c (qemuMigrationIsSafe): Likewise.
* src/util/virstoragefile.h: Adjust declarations.
* src/util/virfile.h: Likewise.
* src/libvirt_private.syms (virfile.h, virstoragefile.h): Move
symbols as appropriate.
Signed-off-by: Eric Blake <eblake@redhat.com>
Part of a series of cleanups to use new accessor methods.
* src/security/security_dac.c (virSecurityDACSetSecurityImageLabel)
(virSecurityDACRestoreSecurityImageLabelInt)
(virSecurityDACSetSecurityAllLabel): Use accessors.
* src/security/security_selinux.c
(virSecuritySELinuxRestoreSecurityImageLabelInt)
(virSecuritySELinuxSetSecurityImageLabel)
(virSecuritySELinuxSetSecurityAllLabel): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
Any source file which calls the logging APIs now needs
to have a VIR_LOG_INIT("source.name") declaration at
the start of the file. This provides a static variable
of the virLogSource type.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
To support passing the path of the test data to the utils, one
more argument is added to virSCSIDeviceGetSgName,
virSCSIDeviceGetDevName, and virSCSIDeviceNew, and the related
code is changed accordingly.
Later tests for the scsi utils will be based on this patch.
Signed-off-by: Osier Yang <jyang@redhat.com>
Unlike the host devices of other types, SCSI host device XML supports
"shareable" tag. This patch introduces it for the virSCSIDevice struct
for a later patch use (to detect if the SCSI device is shareable when
preparing the SCSI host device in QEMU driver).
To ensure proper processing by virGetUserID() and virGetGroupID()
of a uid/gid add a "+" prior to the uid/gid to denote it's really
a uid/gid for the label.
Merge the functions 'virSecurityDACSetUser' and
'virSecurityDACSetGroup' into 'virSecurityDACSetUserAndGroup'.
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
Commit 29fe5d7 (released in 1.1.1) introduced a latent problem
for any caller of virSecurityManagerSetProcessLabel and where
the domain already had a uid:gid label to be parsed. Such a
setup would collect the list of supplementary groups during
virSecurityManagerPreFork, but then ignores that information,
and thus fails to call setgroups() to adjust the supplementary
groups of the process.
Upstream does not use virSecurityManagerSetProcessLabel for
qemu (it uses virSecurityManagerSetChildProcessLabel instead),
so this problem remained latent until backporting the initial
commit into v0.10.2-maint (commit c061ff5, released in 0.10.2.7),
where virSecurityManagerSetChildProcessLabel has not been
backported. As a result of using a different code path in the
backport, attempts to start a qemu domain that runs as qemu:qemu
will end up with supplementary groups unchanged from the libvirtd
parent process, rather than the desired supplementary groups of
the qemu user. This can lead to failure to start a domain
(typical Fedora setup assigns user 107 'qemu' to both group 107
'qemu' and group 36 'kvm', so a disk image that is only readable
under kvm group rights is locked out). Worse, it is a security
hole (the qemu process will inherit supplemental group rights
from the parent libvirtd process, which means it has access
rights to files owned by group 0 even when such files should
not normally be visible to user qemu).
LXC does not use the DAC security driver, so it is not vulnerable
at this time. Still, it is better to plug the latent hole on
the master branch first, before cherry-picking it to the only
vulnerable branch v0.10.2-maint.
* src/security/security_dac.c (virSecurityDACGetIds): Always populate
groups and ngroups, rather than only when no label is parsed.
Signed-off-by: Eric Blake <eblake@redhat.com>
Parsing 'user:group' is useful even outside the DAC security driver,
so expose the most abstract function which has no DAC security driver
bits in itself.
Commit 75c1256 states that virGetGroupList must not be called
between fork and exec, then commit ee777e99 promptly violated
that for lxc's use of virSecurityManagerSetProcessLabel. Hoist
the supplemental group detection to the time that the security
manager needs to fork. Qemu is safe, as it uses
virSecurityManagerSetChildProcessLabel which in turn uses
virCommand to determine supplemental groups.
This does not fix the fact that virSecurityManagerSetProcessLabel
calls virSecurityDACParseIds calls parseIds which eventually
calls getpwnam_r, which also violates fork/exec async-signal-safe
safety rules, but so far no one has complained of hitting
deadlock in that case.
* src/security/security_dac.c (_virSecurityDACData): Track groups
in private data.
(virSecurityDACPreFork): New function, to set them.
(virSecurityDACClose): Clean up new fields.
(virSecurityDACGetIds): Alter signature.
(virSecurityDACSetSecurityHostdevLabelHelper)
(virSecurityDACSetChardevLabel, virSecurityDACSetProcessLabel)
(virSecurityDACSetChildProcessLabel): Update callers.
Signed-off-by: Eric Blake <eblake@redhat.com>
https://bugzilla.redhat.com/show_bug.cgi?id=964358
POSIX states that multi-threaded apps should not use functions
that are not async-signal-safe between fork and exec, yet we
were using getpwuid_r and initgroups. Although rare, it is
possible to hit deadlock in the child, when it tries to grab
a mutex that was already held by another thread in the parent.
I actually hit this deadlock when testing multiple domains
being started in parallel with a command hook, with the following
backtrace in the child:
Thread 1 (Thread 0x7fd56bbf2700 (LWP 3212)):
#0 __lll_lock_wait ()
at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:136
#1 0x00007fd5761e7388 in _L_lock_854 () from /lib64/libpthread.so.0
#2 0x00007fd5761e7257 in __pthread_mutex_lock (mutex=0x7fd56be00360)
at pthread_mutex_lock.c:61
#3 0x00007fd56bbf9fc5 in _nss_files_getpwuid_r (uid=0, result=0x7fd56bbf0c70,
buffer=0x7fd55c2a65f0 "", buflen=1024, errnop=0x7fd56bbf25b8)
at nss_files/files-pwd.c:40
#4 0x00007fd575aeff1d in __getpwuid_r (uid=0, resbuf=0x7fd56bbf0c70,
buffer=0x7fd55c2a65f0 "", buflen=1024, result=0x7fd56bbf0cb0)
at ../nss/getXXbyYY_r.c:253
#5 0x00007fd578aebafc in virSetUIDGID (uid=0, gid=0) at util/virutil.c:1031
#6 0x00007fd578aebf43 in virSetUIDGIDWithCaps (uid=0, gid=0, capBits=0,
clearExistingCaps=true) at util/virutil.c:1388
#7 0x00007fd578a9a20b in virExec (cmd=0x7fd55c231f10) at util/vircommand.c:654
#8 0x00007fd578a9dfa2 in virCommandRunAsync (cmd=0x7fd55c231f10, pid=0x0)
at util/vircommand.c:2247
#9 0x00007fd578a9d74e in virCommandRun (cmd=0x7fd55c231f10, exitstatus=0x0)
at util/vircommand.c:2100
#10 0x00007fd56326fde5 in qemuProcessStart (conn=0x7fd53c000df0,
driver=0x7fd55c0dc4f0, vm=0x7fd54800b100, migrateFrom=0x0, stdin_fd=-1,
stdin_path=0x0, snapshot=0x0, vmop=VIR_NETDEV_VPORT_PROFILE_OP_CREATE,
flags=1) at qemu/qemu_process.c:3694
...
The solution is to split the work of getpwuid_r/initgroups into the
unsafe portions (getgrouplist, called pre-fork) and safe portions
(setgroups, called post-fork).
* src/util/virutil.h (virSetUIDGID, virSetUIDGIDWithCaps): Adjust
signature.
* src/util/virutil.c (virSetUIDGID): Add parameters.
(virSetUIDGIDWithCaps): Adjust clients.
* src/util/vircommand.c (virExec): Likewise.
* src/util/virfile.c (virFileAccessibleAs, virFileOpenForked)
(virDirCreate): Likewise.
* src/security/security_dac.c (virSecurityDACSetProcessLabel):
Likewise.
* src/lxc/lxc_container.c (lxcContainerSetID): Likewise.
* configure.ac (AC_CHECK_FUNCS_ONCE): Check for setgroups, not
initgroups.
Signed-off-by: Eric Blake <eblake@redhat.com>
Convert the type of loop iterators named 'i', 'j', k',
'ii', 'jj', 'kk', to be 'size_t' instead of 'int' or
'unsigned int', also santizing 'ii', 'jj', 'kk' to use
the normal 'i', 'j', 'k' naming
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
I realized after the fact that it's probably better in the long run to
give this function a name that matches the name of the link used in
sysfs to hold the group (iommu_group).
I'm changing it now because I'm about to add several more functions
that deal with iommu groups.
To not introduce more redundant code, helpers are added for
both "selinux", "dac", and "apparmor" backends.
Signed-off-by: Han Cheng <hanc.fnst@cn.fujitsu.com>
Signed-off-by: Osier Yang <jyang@redhat>
v2.5 - v3:
* Splitted from 8/10 of v2.5
* Don't forget the other backends (DAC, and apparmor)
These all existed before virfile.c was created, and for some reason
weren't moved.
This is mostly straightfoward, although the syntax rule prohibiting
write() had to be changed to have an exception for virfile.c instead
of virutil.c.
This movement pointed out that there is a function called
virBuildPath(), and another almost identical function called
virFileBuildPath(). They really should be a single function, which
I'll take care of as soon as I figure out what the arglist should look
like.
The source code base needs to be adapted as well. Some files
include virutil.h just for the string related functions (here,
the include is substituted to match the new file), some include
virutil.h without any need (here, the include is removed), and
some require both.
If virPCIDeviceGetVFIOGroupDev() failed,
virSecurity*(Set|Restore)HostdevLabel() would fail to free a
virPCIDevice that had been allocated.
These leaks were all introduced (by me) very recently, in commit
f0bd70a.
This isn't strictly speaking a bugfix, but I realized I'd gotten a bit
too verbose when I chose the names for
VIR_DOMAIN_HOSTDEV_PCI_BACKEND_TYPE_*. This shortens them all a bit.
Legacy kvm style pci device assignment requires changes to the
labelling of several sysfs files for each device, but for vfio device
assignment, the only thing that needs to be relabelled/chowned is the
"group" device for the group that contains the device to be assigned.
There will soon be other items related to pci hostdevs that need to be
in the same part of the hostdevsubsys union as the pci address (which
is currently a single member called "pci". This patch replaces the
single member named pci with a struct named pci that contains a single
member named "addr".
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.)
