This patch fixes the regression with using named pipes for qemu serial
devices noted in:

  https://bugzilla.redhat.com/show_bug.cgi?id=740478

The problem was that, while new code in libvirt looks for a single
bidirectional fifo of the name given in the config, then relabels that
and continues without looking for / relabelling the two unidirectional
fifos named ${name}.in and ${name}.out, qemu looks in the opposite
order. So if the user had naively created all three fifos, libvirt
would relabel the bidirectional fifo to allow qemu access, but qemu
would attempt to use the two unidirectional fifos and fail (because it
didn't have proper permissions/rights).

This patch changes the order that libvirt looks for the fifos to match
what qemu does - first it looks for the dual fifos, then it looks for
the single bidirectional fifo. If it finds the dual unidirectional
fifos first, it labels/chowns them and ignores any possible
bidirectional fifo.

(Note commit d37c6a3a (which first appeared in libvirt-0.9.2) added
the code that checked for a bidirectional fifo. Prior to that commit,
bidirectional fifos for serial devices didn't work because libvirt
always required the ${name}.(in|out) fifos to exist, and qemu would
always prefer those.

Previous patch c9b37fee tried to deal with virt_use_nfs. But
setfilecon() returns EOPNOTSUPP on NFS so we need to move the
warning to else branch.

If we fail setting label on a file and this file is on NFS share,
it is wise to advise user to set virt_use_nfs selinux boolean
variable.

The virSecurityManagerSetProcessFDLabel method was introduced
after a mis-understanding from a conversation about SELinux
socket labelling. The virSecurityManagerSetSocketLabel method
should have been used for all such scenarios.

* src/security/security_apparmor.c, src/security/security_apparmor.c,
  src/security/security_driver.h, src/security/security_manager.c,
  src/security/security_manager.h, src/security/security_selinux.c,
  src/security/security_stack.c: Remove SetProcessFDLabel driver

This API labels all sockets created until ClearSocketLabel is called in
a way that a vm can access them (i.e., they are labeled with svirt_t
based label in SELinux).

The APIs are designed to label a socket in a way that the libvirt daemon
itself is able to access it (i.e., in SELinux the label is virtd_t based
as opposed to svirt_* we use for labeling resources that need to be
accessed by a vm). The new name reflects this.

In preparation for a future patch adding new virFile APIs.

* src/util/files.h, src/util/files.c: Move...
* src/util/virfile.h, src/util/virfile.c: ...here, and rename
functions to virFile prefix.  Macro names are intentionally
left alone.
* *.c: All '#include "files.h"' uses changed.
* src/Makefile.am (UTIL_SOURCES): Reflect rename.
* cfg.mk (exclude_file_name_regexp--sc_prohibit_close): Likewise.
* src/libvirt_private.syms: Likewise.
* docs/hacking.html.in: Likewise.
* HACKING: Regenerate.

When no <seclabel> is present in the XML, the virDomainSeclabelDef
struct is left as all zeros. Unfortunately, this means it gets setup
as type=dynamic, with relabel=no, which is an illegal combination.

Change the 'bool relabel' attribute in virDomainSeclabelDef to
the inverse 'bool norelabel' so that the default initialization
is sensible

* src/conf/domain_conf.c, src/conf/domain_conf.h,
  src/security/security_apparmor.c, src/security/security_selinux.c:
  Replace 'relabel' with 'norelabel'

Add a new attribute to the <seclabel> XML to allow resource
relabelling to be enabled with static label usage.

  <seclabel model='selinux' type='static' relabel='yes'>
    <label>system_u:system_r:svirt_t:s0:c392,c662</label>
  </seclabel>

* docs/schemas/domain.rng: Add relabel attribute
* src/conf/domain_conf.c, src/conf/domain_conf.h: Parse
  the 'relabel' attribute
* src/qemu/qemu_process.c: Unconditionally clear out the
  'imagelabel' attribute
* src/security/security_apparmor.c: Skip based on 'relabel'
  attribute instead of label type
* src/security/security_selinux.c: Skip based on 'relabel'
  attribute instead of label type and fill in <imagelabel>
  attribute if relabel is enabled.

Normally the dynamic labelling mode will always use a base
label of 'svirt_t' for VMs. Introduce a <baselabel> field
in the <seclabel> XML to allow this base label to be changed

eg

   <seclabel type='dynamic' model='selinux'>
     <baselabel>system_u:object_r:virt_t:s0</baselabel>
   </seclabel>

* docs/schemas/domain.rng: Add <baselabel>
* src/conf/domain_conf.c, src/conf/domain_conf.h: Parsing
  of base label
* src/qemu/qemu_process.c: Don't reset 'model' attribute if
  a base label is specified
* src/security/security_apparmor.c: Refuse to support base label
* src/security/security_selinux.c: Use 'baselabel' when generating
  label, if available

Add a new security driver method for labelling an FD with
the process label, rather than the image label

* src/libvirt_private.syms, src/security/security_apparmor.c,
  src/security/security_dac.c, src/security/security_driver.h,
  src/security/security_manager.c, src/security/security_manager.h,
  src/security/security_selinux.c, src/security/security_stack.c:
  Add virSecurityManagerSetProcessFDLabel & impl

The virSecurityManagerSetFDLabel method is used to label
file descriptors associated with disk images. There will
shortly be a need to label other file descriptors in a
different way. So the current name is ambiguous. Rename
the method to virSecurityManagerSetImageFDLabel to clarify
its purpose

* src/libvirt_private.syms,
  src/qemu/qemu_migration.c, src/qemu/qemu_process.c,
  src/security/security_apparmor.c, src/security/security_dac.c,
  src/security/security_driver.h, src/security/security_manager.c,
  src/security/security_manager.h, src/security/security_selinux.c,
  src/security/security_stack.c: s/FDLabel/ImageFDLabel/

When setting up a FIFO for QEMU, it allows either a pair
of fifos used unidirectionally, or a single fifo used
bidirectionally. Look for the bidirectional fifo first
when labelling since that is more useful

* src/security/security_dac.c,
  src/security/security_selinux.c: Fix fifo handling

Even with -Wuninitialized (which is part of autobuild.sh
--enable-compile-warnings=error), gcc does NOT catch this
use of an uninitialized variable:

{
  if (cond)
    goto error;
  int a = 1;
error:
  printf("%d", a);
}

which prints 0 (supposing the stack started life wiped) if
cond was true.  Clang will catch it, but we don't use clang
as often.  Using gcc -Wjump-misses-init catches it, but also
gives false positives:

{
  if (cond)
    goto error;
  int a = 1;
  return a;
error:
  return 0;
}

Here, a was never used in the scope of the error block, so
declaring it after goto is technically fine (and clang agrees).
However, given that our HACKING already documents a preference
to C89 decl-before-statement, the false positive warning is
enough of a prod to comply with HACKING.

[Personally, I'd _really_ rather use C99 decl-after-statement
to minimize scope, but until gcc can efficiently and reliably
catch scoping and uninitialized usage bugs, I'll settle with
the compromise of enforcing a coding standard that happens to
reject false positives if it can also detect real bugs.]

* acinclude.m4 (LIBVIRT_COMPILE_WARNINGS): Add -Wjump-misses-init.
* src/util/util.c (__virExec): Adjust offenders.
* src/conf/domain_conf.c (virDomainTimerDefParseXML): Likewise.
* src/remote/remote_driver.c (doRemoteOpen): Likewise.
* src/phyp/phyp_driver.c (phypGetLparNAME, phypGetLparProfile)
(phypGetVIOSFreeSCSIAdapter, phypVolumeGetKey)
(phypGetStoragePoolDevice)
(phypVolumeGetPhysicalVolumeByStoragePool)
(phypVolumeGetPath): Likewise.
* src/vbox/vbox_tmpl.c (vboxNetworkUndefineDestroy)
(vboxNetworkCreate, vboxNetworkDumpXML)
(vboxNetworkDefineCreateXML): Likewise.
* src/xenapi/xenapi_driver.c (getCapsObject)
(xenapiDomainDumpXML): Likewise.
* src/xenapi/xenapi_utils.c (createVMRecordFromXml): Likewise.
* src/security/security_selinux.c (SELinuxGenNewContext):
Likewise.
* src/qemu/qemu_command.c (qemuBuildCommandLine): Likewise.
* src/qemu/qemu_hotplug.c (qemuDomainChangeEjectableMedia):
Likewise.
* src/qemu/qemu_process.c (qemuProcessWaitForMonitor): Likewise.
* src/qemu/qemu_monitor_text.c (qemuMonitorTextGetPtyPaths):
Likewise.
* src/qemu/qemu_driver.c (qemudDomainShutdown)
(qemudDomainBlockStats, qemudDomainMemoryPeek): Likewise.
* src/storage/storage_backend_iscsi.c
(virStorageBackendCreateIfaceIQN): Likewise.
* src/node_device/node_device_udev.c (udevProcessPCI): Likewise.

* src/security/security_selinux.c
(SELinuxRestoreSecuritySmartcardCallback)
(SELinuxSetSecuritySmartcardCallback): New helper functions.
(SELinuxRestoreSecurityAllLabel, SELinuxSetSecurityAllLabel): Use
them.

A need was found to set the SELinux context label on an open fd (a
pipe, as a matter of fact). This patch adds a function to the security
driver API that will set the label on an open fd to secdef.label. For
all drivers other than the SELinux driver, it's a NOP. For the SElinux
driver, it calls fsetfilecon().

If the return is a failure, it only returns error up to the caller if
1) the desired label is different from the existing label, 2) the
destination fd is of a type that supports setting the selinux context,
and 3) selinux is in enforcing mode. Otherwise it will return
success. This follows the pattern of the existing function
SELinuxSetFilecon().

This opens up the possibility of reusing the smaller ChrSourceDef
for both qemu monitor and a passthrough smartcard device.

* src/conf/domain_conf.h (_virDomainChrDef): Factor host
details...
(_virDomainChrSourceDef): ...into new struct.
(virDomainChrSourceDefFree): New prototype.
* src/conf/domain_conf.c (virDomainChrDefFree)
(virDomainChrDefParseXML, virDomainChrDefFormat): Split...
(virDomainChrSourceDefClear, virDomainChrSourceDefFree)
(virDomainChrSourceDefParseXML, virDomainChrSourceDefFormat):
...into new functions.
(virDomainChrDefParseTargetXML): Update clients to reflect type
split.
* src/vmx/vmx.c (virVMXParseSerial, virVMXParseParallel)
(virVMXFormatSerial, virVMXFormatParallel): Likewise.
* src/xen/xen_driver.c (xenUnifiedDomainOpenConsole): Likewise.
* src/xen/xend_internal.c (xenDaemonParseSxprChar)
(xenDaemonFormatSxprChr): Likewise.
* src/vbox/vbox_tmpl.c (vboxDomainDumpXML, vboxAttachSerial)
(vboxAttachParallel): Likewise.
* src/security/security_dac.c (virSecurityDACSetChardevLabel)
(virSecurityDACSetChardevCallback)
(virSecurityDACRestoreChardevLabel)
(virSecurityDACRestoreChardevCallback): Likewise.
* src/security/security_selinux.c (SELinuxSetSecurityChardevLabel)
(SELinuxSetSecurityChardevCallback)
(SELinuxRestoreSecurityChardevLabel)
(SELinuxSetSecurityChardevCallback): Likewise.
* src/security/virt-aa-helper.c (get_files): Likewise.
* src/lxc/lxc_driver.c (lxcVmStart, lxcDomainOpenConsole):
Likewise.
* src/uml/uml_conf.c (umlBuildCommandLineChr): Likewise.
* src/uml/uml_driver.c (umlIdentifyOneChrPTY, umlIdentifyChrPTY)
(umlDomainOpenConsole): Likewise.
* src/qemu/qemu_command.c (qemuBuildChrChardevStr)
(qemuBuildChrArgStr, qemuBuildCommandLine)
(qemuParseCommandLineChr): Likewise.
* src/qemu/qemu_domain.c (qemuDomainObjPrivateXMLFormat)
(qemuDomainObjPrivateXMLParse): Likewise.
* src/qemu/qemu_cgroup.c (qemuSetupChardevCgroup): Likewise.
* src/qemu/qemu_hotplug.c (qemuDomainAttachNetDevice): Likewise.
* src/qemu/qemu_driver.c (qemudFindCharDevicePTYsMonitor)
(qemudFindCharDevicePTYs, qemuPrepareChardevDevice)
(qemuPrepareMonitorChr, qemudShutdownVMDaemon)
(qemuDomainOpenConsole): Likewise.
* src/qemu/qemu_command.h (qemuBuildChrChardevStr)
(qemuBuildChrArgStr): Delete, now that they are static.
* src/libvirt_private.syms (domain_conf.h): New exports.
* cfg.mk (useless_free_options): Update list.
* tests/qemuxml2argvtest.c (testCompareXMLToArgvFiles): Update
tests.

The current security driver usage requires horrible code like

    if (driver->securityDriver &&
        driver->securityDriver->domainSetSecurityHostdevLabel &&
        driver->securityDriver->domainSetSecurityHostdevLabel(driver->securityDriver,
                                                              vm, hostdev) < 0)

This pair of checks for NULL clutters up the code, making the driver
calls 2 lines longer than they really need to be. The goal of the
patchset is to change the calling convention to simply

  if (virSecurityManagerSetHostdevLabel(driver->securityDriver,
                                        vm, hostdev) < 0)

The first check for 'driver->securityDriver' being NULL is removed
by introducing a 'no op' security driver that will always be present
if no real driver is enabled. This guarentees driver->securityDriver
!= NULL.

The second check for 'driver->securityDriver->domainSetSecurityHostdevLabel'
being non-NULL is hidden in a new abstraction called virSecurityManager.
This separates the driver callbacks, from main internal API. The addition
of a virSecurityManager object, that is separate from the virSecurityDriver
struct also allows for security drivers to carry state / configuration
information directly. Thus the DAC/Stack drivers from src/qemu which
used to pull config from 'struct qemud_driver' can now be moved into
the 'src/security' directory and store their config directly.

* src/qemu/qemu_conf.h, src/qemu/qemu_driver.c: Update to
  use new virSecurityManager APIs
* src/qemu/qemu_security_dac.c,  src/qemu/qemu_security_dac.h
  src/qemu/qemu_security_stacked.c, src/qemu/qemu_security_stacked.h:
  Move into src/security directory
* src/security/security_stack.c, src/security/security_stack.h,
  src/security/security_dac.c, src/security/security_dac.h: Generic
  versions of previous QEMU specific drivers
* src/security/security_apparmor.c, src/security/security_apparmor.h,
  src/security/security_driver.c, src/security/security_driver.h,
  src/security/security_selinux.c, src/security/security_selinux.h:
  Update to take virSecurityManagerPtr object as the first param
  in all callbacks
* src/security/security_nop.c, src/security/security_nop.h: Stub
  implementation of all security driver APIs.
* src/security/security_manager.h, src/security/security_manager.c:
  New internal API for invoking security drivers
* src/libvirt.c: Add missing debug for security APIs

Network disks are accessed by qemu directly, and have no
associated file on the host, so checking for file ownership etc.
is unnecessary.
Signed-off-by: NJosh Durgin <joshd@hq.newdream.net>

* configure.ac (with_selinux): Check for <selinux/label.h>.
* src/security/security_selinux.c (getContext): New function.
(SELinuxRestoreSecurityFileLabel): Use it to restore compilation
when using older libselinux.

https://bugzilla.redhat.com/show_bug.cgi?id=658657

* src/security/security_selinux.c
(SELinuxRestoreSecurityFileLabel): Use selabel_lookup instead of
matchpathcon.
Suggested by Daniel Walsh.

security_context_t happens to be a typedef for char*, and happens to
begin with a string usable as a raw context string.  But in reality,
it is an opaque type that may or may not have additional information
after the first NUL byte, where that additional information can
include pointers that can only be freed via freecon().

Proof is from this valgrind run of daemon/libvirtd:

==6028== 839,169 (40 direct, 839,129 indirect) bytes in 1 blocks are definitely lost in loss record 274 of 274
==6028==    at 0x4A0515D: malloc (vg_replace_malloc.c:195)
==6028==    by 0x3022E0D48C: selabel_open (label.c:165)
==6028==    by 0x3022E11646: matchpathcon_init_prefix (matchpathcon.c:296)
==6028==    by 0x3022E1190D: matchpathcon (matchpathcon.c:317)
==6028==    by 0x4F9D842: SELinuxRestoreSecurityFileLabel (security_selinux.c:382)

800k is a lot of memory to be leaking.

* src/storage/storage_backend.c
(virStorageBackendUpdateVolTargetInfoFD): Avoid leak on error.
* src/security/security_selinux.c
(SELinuxReserveSecurityLabel, SELinuxGetSecurityProcessLabel)
(SELinuxRestoreSecurityFileLabel): Use correct function to free
security_context_t.

The code in SELinuxRestoreSecurityChardevLabel() was trying to
use SELinuxSetFilecon directly for devices or file types while
it should really use SELinuxRestoreSecurityFileLabel encapsulating
routine, which avoid various problems like resolving symlinks,
making sure he file exists and work around NFS problems

* cfg.mk (sc_prohibit_sprintf): New rule.
(sc_prohibit_asprintf): Avoid false positives.
* docs/hacking.html.in (Printf-style functions): Document the
policy.
* HACKING: Regenerate.
* .x-sc_prohibit_sprintf: New exemptions.
* Makefile.am (syntax_check_exceptions): Ship new file.
* src/vbox/vbox_tmpl.c (vboxStartMachine, vboxAttachUSB): Use
virAsprintf instead.
* src/uml/uml_driver.c (umlOpenMonitor): Use snprintf instead.
* tools/virsh.c (cmdDetachInterface): Likewise.
* src/security/security_selinux.c (SELinuxGenSecurityLabel):
Likewise.
* src/openvz/openvz_driver.c (openvzDomainDefineCmd): Likewise,
and ensure large enough buffer.

If virDomainAttachDevice() was called with an image that was located
on a root-squashed NFS server, and in a directory that was unreadable
by root on the machine running libvirtd, the attach would fail due to
an attempt to change the selinux label of the image with EACCES (which
isn't covered as an ignore case in SELinuxSetFilecon())

NFS doesn't support SELinux labelling anyway, so we mimic the failure
handling of commit 93a18bba, which
just ignores the errors if the target is on an NFS filesystem (in
SELinuxSetSecurityAllLabel() only, though.)

This can be seen as a follow-on to commit
347d266c, which ignores file open
failures of files on NFS that occur directly in
virDomainDiskDefForeachPath() (also necessary), but does not ignore
failures in functions that are called from there (eg
SELinuxSetSecurityFileLabel()).

Using automated replacement with sed and editing I have now replaced all
occurrences of close() with VIR_(FORCE_)CLOSE() except for one, of
course. Some replacements were straight forward, others I needed to pay
attention. I hope I payed attention in all the right places... Please
have a look. This should have at least solved one more double-close
error.

NFS in root squash mode may prevent opening disk images to
determine backing store. Ignore errors in this scenario.

* src/security/security_selinux.c: Ignore open failures on disk
  images

NFS does not support file labelling, so ignore this error
for stdin_path when on NFS.

* src/security/security_selinux.c: Ignore failures on labelling
  stdin_path on NFS
* src/util/storage_file.c, src/util/storage_file.h: Refine
  virStorageFileIsSharedFS() to allow it to check for a
  specific FS type.

This reverts commit b8e2de88
The hooks will be re-added in the QEMU driver itself.

* src/security/security_selinux.c: Remove audit hooks

A more natural auditing point would perhaps be
SELinuxSetSecurityProcessLabel, but this happens in the child after root
permissions are dropped, so the kernel would refuse the audit record.

Disk format probing is now disabled by default. A new config
option in /etc/qemu/qemu.conf will re-enable it for existing
deployments where this causes trouble

The implementation of security driver callbacks often needs
to access the security driver object. Currently only a handful
of callbacks include the driver object as a parameter. Later
patches require this is many more places.

* src/qemu/qemu_driver.c: Pass in the security driver object
  to all callbacks
* src/qemu/qemu_security_dac.c, src/qemu/qemu_security_stacked.c,
  src/security/security_apparmor.c, src/security/security_driver.h,
  src/security/security_selinux.c: Add a virSecurityDriverPtr
  param to all security callbacks

Update the QEMU cgroups code, QEMU DAC security driver, SELinux
and AppArmour security drivers over to use the shared helper API
virDomainDiskDefForeachPath().

* src/qemu/qemu_driver.c, src/qemu/qemu_security_dac.c,
  src/security/security_selinux.c, src/security/virt-aa-helper.c:
  Convert over to use virDomainDiskDefForeachPath()

Require the disk image to be passed into virStorageFileGetMetadata.
If this is set to VIR_STORAGE_FILE_AUTO, then the format will be
resolved using probing. This makes it easier to control when
probing will be used

* src/qemu/qemu_driver.c, src/qemu/qemu_security_dac.c,
  src/security/security_selinux.c, src/security/virt-aa-helper.c:
  Set VIR_STORAGE_FILE_AUTO when calling virStorageFileGetMetadata.
* src/storage/storage_backend_fs.c: Probe for disk format before
  calling virStorageFileGetMetadata.
* src/util/storage_file.h, src/util/storage_file.c: Remove format
  from virStorageFileMeta struct & require it to be passed into
  method.

Also restore the label to its original value after qemu is finished
with the file.

Prior to this patch, qemu domain restore did not function properly if
selinux was set to enforce.

When configuring serial, parallel, console or channel devices
with a file, dev or pipe backend type, it is necessary to label
the file path in the security drivers. For char devices of type
file, it is neccessary to pre-create (touch) the file if it does
not already exist since QEMU won't be allowed todo so itself.
dev/pipe configs already require the admin to pre-create before
starting the guest.

* src/qemu/qemu_security_dac.c: set file ownership for character
  devices
* src/security/security_selinux.c: Set file labeling for character
  devices
* src/qemu/qemu_driver.c: Add character devices to cgroup ACL

The restore code is done in places where errors cannot be
raised, since they will overwrite over pre-existing errors.

* src/security/security_selinux.c: Only warn about failures
  in label restore, don't report errors

When SELinux is running in MLS mode, libvirtd will have a
different security level to the VMs. For libvirtd to be
able to connect to the monitor console, the client end of
the UNIX domain socket needs a different label. This adds
infrastructure to set the socket label via the security
driver framework

* src/qemu/qemu_driver.c: Call out to socket label APIs in
  security driver
* src/qemu/qemu_security_stacked.c: Wire up socket label
  drivers
* src/security/security_driver.h: Define security driver
  entry points for socket labelling
* src/security/security_selinux.c: Set socket label based on
  VM label

Adjust args to qemudStartVMDaemon() to also specify path to stdin_fd,
so this can be passed to the AppArmor driver via SetSecurityAllLabel().

This updates all calls to qemudStartVMDaemon() as well as setting up
the non-AppArmor security driver *SetSecurityAllLabel() declarations
for the above. This is required for the following
"apparmor-fix-save-restore" patch since AppArmor resolves the passed
file descriptor to the pathname given to open().

Do not require each caller of virStorageFileGetMetadata and
virStorageFileGetMetadataFromFD to first clear the storage of the
"meta" buffer.  Instead, initialize that storage in
virStorageFileGetMetadataFromFD.
* src/util/storage_file.c (virStorageFileGetMetadataFromFD): Clear
"meta" here, not before each of the following callers.
* src/qemu/qemu_driver.c (qemuSetupDiskCgroup): Don't clear "meta" here.
(qemuTeardownDiskCgroup): Likewise.
* src/qemu/qemu_security_dac.c (qemuSecurityDACSetSecurityImageLabel):
Likewise.
* src/security/security_selinux.c (SELinuxSetSecurityImageLabel):
Likewise.
* src/security/virt-aa-helper.c (get_files): Likewise.