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.
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Michal Privoznik bb4e529664 qemu: Spawn qemu under mount namespace
Prime time. When it comes to spawning qemu process and
relabelling all the devices it's going to touch, there's inherent
race with other applications in the system (e.g. udev). Instead
of trying convincing udev to not touch libvirt managed devices,
we can create a separate mount namespace for the qemu, and mount
our own /dev there. Of course this puts more work onto us as we
have to maintain /dev files on each domain start and device
hot(un-)plug. On the other hand, this enhances security also.

From technical POV, on domain startup process the parent
(libvirtd) creates:

  /var/lib/libvirt/qemu/$domain.dev
  /var/lib/libvirt/qemu/$domain.devpts

The child (which is going to be qemu eventually) calls unshare()
to create new mount namespace. From now on anything that child
does is invisible to the parent. Child then mounts tmpfs on
$domain.dev (so that it still sees original /dev from the host)
and creates some devices (as explained in one of the previous
patches). The devices have to be created exactly as they are in
the host (including perms, seclabels, ACLs, ...). After that it
moves $domain.dev mount to /dev.

What's the $domain.devpts mount there for then you ask? QEMU can
create PTYs for some chardevs. And historically we exposed the
host ends in our domain XML allowing users to connect to them.
Therefore we must preserve devpts mount to be shared with the
host's one.

To make this patch as small as possible, creating of devices
configured for domain in question is implemented in next patches.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
2016-12-15 09:25:16 +01:00
.gnulib@c3b131294a build: update to latest gnulib 2016-11-15 10:26:58 -06:00
build-aux prohibit-duplicate-header: print file name and line 2016-06-23 12:48:40 +02:00
daemon Fix minor typos 2016-12-02 09:25:13 +01:00
docs schema: Let elements in /network/ip be specified in any order 2016-12-14 16:20:23 +01:00
examples AppArmor: allow QEMU to set_process_name. 2016-12-12 14:08:45 +00:00
gnulib build: drop hack for old mingw ssize_t 2016-07-12 08:57:13 -06:00
include/libvirt perf: add branch_misses perf event support 2016-12-12 18:04:52 -05:00
m4 m4/virt-lib: properly pass header_name in LIBVIRT_CHECK_LIB(_ALT) 2016-12-07 16:21:31 +01:00
po Move virstat.c code to virnetdevtap.c 2016-12-09 10:28:07 +01:00
src qemu: Spawn qemu under mount namespace 2016-12-15 09:25:16 +01:00
tests schema: Let elements in /network/ip be specified in any order 2016-12-14 16:20:23 +01:00
tools perf: add branch_misses perf event support 2016-12-12 18:04:52 -05:00
.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 tests: Self test virt-admin 2016-09-14 13:18:07 +02:00
.gitmodules
.mailmap maint: update .mailmap for recent contributions 2015-03-20 06:17:55 -06:00
AUTHORS.in Change maintainers list 2016-02-12 13:10:05 +03:00
autobuild.sh maint: Switch to xz compressed PAX release archives 2016-06-15 18:53:34 +02:00
autogen.sh maint: improve usage of autogen's --no-git 2015-02-06 11:35:29 -07:00
bootstrap build: update to latest gnulib 2016-11-12 14:51:52 -06:00
bootstrap.conf hvsupport: use a regex instead of XML::XPath 2016-07-19 18:42:44 +02:00
cfg.mk nssmock: Prefer free() over VIR_FREE() 2016-12-06 13:33:18 +01:00
ChangeLog-old Fix typos in src/* 2014-04-21 16:49:08 -06:00
config-post.h virfile: Introduce ACL helpers 2016-12-15 09:25:16 +01:00
configure.ac virfile: Introduce ACL helpers 2016-12-15 09:25:16 +01:00
COPYING maint: follow recommended practice for using LGPL 2013-05-20 14:15:21 -06:00
COPYING.LESSER maint: Remove control characters from LGPL license file 2015-09-25 09:16:24 +02:00
HACKING docs: remove outdated suggestion to make patches with "diff -urp"/"git diff" 2016-07-01 12:41:10 -04:00
libvirt-admin.pc.in Add libvirt-admin library 2015-06-16 13:46:20 +02:00
libvirt-lxc.pc.in Add pkg-config files for libvirt-qemu & libvirt-lxc 2014-06-23 16:17:27 +01:00
libvirt-qemu.pc.in Add pkg-config files for libvirt-qemu & libvirt-lxc 2014-06-23 16:17:27 +01:00
libvirt.pc.in Add pkg-config files for libvirt-qemu & libvirt-lxc 2014-06-23 16:17:27 +01:00
libvirt.spec.in libvirt.spec: Package libnss_libvirt_guest.so.2 2016-12-08 15:25:17 +01:00
Makefile.am dist: Speed up distribution compression 2016-06-30 16:05:24 +02:00
Makefile.nonreentrant cfg.mk: use a single regex for all non-reentrant functions 2016-06-15 15:00:56 +02:00
mingw-libvirt.spec.in test: fix screenshot API impl 2016-12-08 10:57:32 +00:00
README
README-hacking docs: update README-hacking 2014-05-06 16:20:24 -06:00
run.in Add PKG_CONFIG_PATH to run.in script. 2014-06-26 14:32:35 +01:00
TODO

         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>