Libvirt provides a portable, long term stable C API for managing the virtualization technologies provided by many operating systems. It includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER Hypervisor.
Go to file
Eric Blake 359f4b11a6 qemu: don't munge user input during block commit
While investigating https://bugzilla.redhat.com/show_bug.cgi?id=1061827
I noticed that we pass user input unscathed for block-pull, but
always pass a canonical absolute name through for block-commit.
[Note that we probably _ought_ to validate that the user's request
for block-pull actually matches the backing chain, the way we already
do for block-commit - but that's a separate issue.  Further note that
the ability to pass user input through unscathed allows backdoors
such as specifying a backing image that is a network URI such as
a gluster disk, instead of forcing things to the local file system;
which is an area still under active investigation on whether libvirt
needs to behave differently for network disks.]

Since qemu may write the name that the user passed in as the backing
file, a user may have a reason to want a relative file name passed
through to qemu, and always munging things to absolute prevents that.

Put another way, if you have the backing chain:

[A] <- [B(back=./A)] <- [C(back=./B)]

and commit B into A (virsh blockcommit $dom vda --base A --top B),
the metadata of C will have to be re-written. But should it be
rewritten as [C(back=./A)] or as [C(back=/path/to/A)]?  Still up in
the air is whether qemu's decision should be based on whether B
and/or C had relative paths, or on whether the --base and/or
--top arguments to the command were relative paths; but if we always
pass a canonical name, we've prevented the spelling of the command
arguments from being part of the hueristics that qemu uses.

I also audited the code, and verified that we never call
qemuMonitorBlockCommit() with a NULL base, either before or after
the change to qemu_driver.c.

* src/qemu/qemu_driver.c (qemuDomainBlockCommit): Preserve user's
spelling, since absolute vs. relative matters to qemu.
* src/qemu/qemu_monitor.h (qemuMonitorBlockCommit): Base is never
null.
* src/qemu/qemu_monitor.c (qemuMonitorBlockCommit): Likewise.
* src/qemu/qemu_monitor_json.h (qemuMonitorJSONBlockCommit):
Likewise.
* src/qemu/qemu_monitor_json.c (qemuMonitorJSONBlockCommit):
Likewise.

Signed-off-by: Eric Blake <eblake@redhat.com>
2014-03-11 17:53:19 -06:00
.gnulib@72fb9075b2 maint: update to latest gnulib, for older autoconf 2014-02-21 17:18:34 -07:00
build-aux Make syntax check notice assignments w/o surrounding spaces. 2014-01-20 14:35:26 +01:00
daemon Add helper APIs to track if libvirtd or loadable modules have changed 2014-03-11 10:51:49 +00:00
docs doc: storage: Explicitly state that it's possible to have non-unique key 2014-03-05 09:51:24 +01:00
examples add support for apparmor in lxc-enter-namespace 2014-03-04 11:15:47 +00:00
gnulib maint: update to latest gnulib 2014-01-01 06:02:47 -07:00
include Add helper APIs for generating cryptographic hashes 2014-03-10 16:39:18 +00:00
m4 build: use --with-systemd-daemon as configure option 2014-02-26 05:59:22 -07:00
po Remove broken error reporting in QEMU mac filtering 2014-03-11 11:04:55 +00:00
src qemu: don't munge user input during block commit 2014-03-11 17:53:19 -06:00
tests tests: Distribute securityselinuxhelperdata 2014-03-11 11:07:52 +01:00
tools Change file names in comments to match the files they are in 2014-03-10 14:26:04 +01:00
.ctags maint: Make ctags work out of the box 2013-07-18 08:47:21 +02:00
.dir-locals.el build: avoid tabs that failed syntax-check 2012-09-06 09:43:46 -06:00
.gitignore Wildcard ignore tests/*test instead of listing every one 2014-03-10 13:22:17 +00:00
.gitmodules make .gnulib a submodule 2009-07-08 16:17:51 +02:00
.mailmap Autogenerate AUTHORS 2012-10-19 12:44:56 -04:00
AUTHORS.in Add Roman Bogorodskiy to the committers list 2014-02-20 20:51:08 +04:00
autobuild.sh Remove python binding 2013-11-25 16:08:00 +00:00
autogen.sh autogen.sh: Correctly detect .git as a file 2013-08-29 13:19:45 +02:00
bootstrap maint: update to latest gnulib 2014-01-01 06:02:47 -07:00
bootstrap.conf Add helpers for getting env vars in a setuid environment 2013-10-21 14:03:52 +01:00
cfg.mk Change file names in comments to match the files they are in 2014-03-10 14:26:04 +01:00
ChangeLog-old maint: typo fixes 2013-10-22 16:49:32 +01:00
config-post.h build: fix build of virt-login-shell on systems with older gnutls 2013-10-22 09:41:50 -06:00
configure.ac Fix missing char dev lock path case in configure 2014-03-05 22:51:59 +04:00
COPYING maint: follow recommended practice for using LGPL 2013-05-20 14:15:21 -06:00
COPYING.LESSER maint: follow recommended practice for using LGPL 2013-05-20 14:15:21 -06:00
HACKING maint: enforce comma style usage 2013-11-20 09:24:18 -07:00
libvirt.pc.in Add missing 'libvirt_lxc_api' variable in pkg-config file 2013-09-04 14:52:40 +01:00
libvirt.spec.in spec: Let translations be properly updated 2014-03-06 22:18:11 +01:00
Makefile.am Introduce Libvirt Wireshark dissector 2014-01-20 17:09:41 +01:00
Makefile.nonreentrant maint: use LGPL correctly 2013-05-20 14:03:48 -06:00
mingw-libvirt.spec.in Remove python binding 2013-11-25 16:08:00 +00:00
README Correct typos in the documentation (Atsushi SAKAI) 2008-01-24 10:15:13 +00:00
README-hacking maint: relax git minimum version 2010-02-24 14:29:27 -05:00
run.in Remove python binding 2013-11-25 16:08:00 +00:00
TODO Update todo list file to point at bugzilla/website 2010-10-13 16:45:26 +01:00

         LibVirt : simple API for virtualization

  Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.

Daniel Veillard <veillard@redhat.com>