Our current defaults are root:wheel on FreeBSD and macOS, root:root
everywhere else.
Looking at what downstream distributions actually do, we can see that
these defaults are overriden the vast majority of the time, with a
number of variations showing up in the wild:
* qemu:qemu -> Used by CentOS, Fedora, Gentoo, OpenSUSE, RHEL
and... As it turns out, our very own spec file :)
* libvirt-qemu:libvirt-qemu -> Used by Debian.
* libvirt-qemu:kvm -> Used by Ubuntu.
* nobody:nobody -> Used by Arch Linux.
Based on this information, we can do a better job at integrating with
downstream packages: if the distro-specific user and group already
exist on the system then we use them, and if not (or we're building
on an unknown OS) we just use root:root as we would have before.
This change makes it less likely that people building from source
will end up running their guests as root, which from the security
point of view is a very desiderable outcome.
Signed-off-by: Andrea Bolognani <abologna@redhat.com>
---
Proof that I'm not making any of this up:
* Alpine Linux
https://github.com/alpinelinux/aports/blob/master/main/libvirt/APKBUILD
* Arch Linux
https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=libvirt-git#n113
* CentOS
https://git.centos.org/blob/rpms!libvirt.git/8d86411e5109d791edf49c7f43c08a06b80896af/SPECS!libvirt.spec#L226
* Debian
https://salsa.debian.org/libvirt-team/libvirt/blob/debian/sid/debian/rules#L94-95
* Fedora
https://src.fedoraproject.org/rpms/libvirt/blob/f29/f/libvirt.spec#_204
* FreeBSD
https://github.com/freebsd/freebsd-ports/blob/master/devel/libvirt/Makefile
* Gentoo
https://github.com/gentoo/gentoo/blob/master/app-emulation/libvirt/libvirt-5.1.0.ebuild#L296-L297
* macOS (Homebrew)
https://github.com/Homebrew/homebrew-core/blob/master/Formula/libvirt.rb
* OpenSUSE
https://build.opensuse.org/package/view_file/openSUSE:Leap:15.0:Update/libvirt/libvirt.spec?expand=1
* Ubuntu
https://git.launchpad.net/ubuntu/+source/libvirt/tree/debian/rules?h=ubuntu/disco#n99
* Upstream :)
https://libvirt.org/git/?p=libvirt.git;a=blob;f=libvirt.spec.in;h=b7a35a0fb14f3360eb795c4ec9b0e46171d2e4ec;hb=HEAD#l196
m4/virt-driver-qemu.m4 | 30 ++++++++++++++++++++++++++++--
1 file changed, 28 insertions(+), 2 deletions(-)
diff --git a/m4/virt-driver-qemu.m4 b/m4/virt-driver-qemu.m4
index cb05c34265..5d4ac66a4b 100644
--- a/m4/virt-driver-qemu.m4
+++ b/m4/virt-driver-qemu.m4
@@ -44,8 +44,34 @@ AC_DEFUN([LIBVIRT_DRIVER_CHECK_QEMU], [
default_qemu_user=root
default_qemu_group=wheel
else
- default_qemu_user=root
- default_qemu_group=root
+ # Try to integrate gracefully with downstream packages by running QEMU
+ # processes under the same user and group they would
+ case $(grep ^ID= /etc/os-release 2>/dev/null) in
+ *arch*)
+ default_qemu_user=nobody
+ default_qemu_group=nobody
+ ;;
+ *centos*|*fedora*|*gentoo*|*rhel*|*suse*)
+ default_qemu_user=qemu
+ default_qemu_group=qemu
+ ;;
+ *debian*)
+ default_qemu_user=libvirt-qemu
+ default_qemu_group=libvirt-qemu
+ ;;
+ *ubuntu*)
+ default_qemu_user=libvirt-qemu
+ default_qemu_group=kvm
+ ;;
+ esac
+ # If the expected user and group don't exist, or we haven't hit any
+ # of the cases above because we're running on an unknown OS, the only
+ # sensible fallback is root:root
+ if ! getent passwd "$default_qemu_user" >/dev/null 2>&1 || \
+ ! getent group "$default_qemu_group" >/dev/null 2>&1; then
+ default_qemu_user=root
+ default_qemu_group=root
+ fi
fi
if test "x$with_qemu_user" = "xplatform dependent" ; then
--
2.20.1
--
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On Tue, Mar 26, 2019 at 05:06:15PM +0100, Andrea Bolognani wrote:
> Our current defaults are root:wheel on FreeBSD and macOS, root:root
> everywhere else.
>
> Looking at what downstream distributions actually do, we can see that
> these defaults are overriden the vast majority of the time, with a
> number of variations showing up in the wild:
>
> * qemu:qemu -> Used by CentOS, Fedora, Gentoo, OpenSUSE, RHEL
> and... As it turns out, our very own spec file :)
>
> * libvirt-qemu:libvirt-qemu -> Used by Debian.
>
> * libvirt-qemu:kvm -> Used by Ubuntu.
>
> * nobody:nobody -> Used by Arch Linux.
>
> Based on this information, we can do a better job at integrating with
> downstream packages: if the distro-specific user and group already
> exist on the system then we use them, and if not (or we're building
> on an unknown OS) we just use root:root as we would have before.
>
> This change makes it less likely that people building from source
> will end up running their guests as root, which from the security
> point of view is a very desiderable outcome.
>
> Signed-off-by: Andrea Bolognani <abologna@redhat.com>
> ---
>
> Proof that I'm not making any of this up:
>
> * Alpine Linux
> https://github.com/alpinelinux/aports/blob/master/main/libvirt/APKBUILD
>
> * Arch Linux
> https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=libvirt-git#n113
>
> * CentOS
> https://git.centos.org/blob/rpms!libvirt.git/8d86411e5109d791edf49c7f43c08a06b80896af/SPECS!libvirt.spec#L226
>
> * Debian
> https://salsa.debian.org/libvirt-team/libvirt/blob/debian/sid/debian/rules#L94-95
>
> * Fedora
> https://src.fedoraproject.org/rpms/libvirt/blob/f29/f/libvirt.spec#_204
>
> * FreeBSD
> https://github.com/freebsd/freebsd-ports/blob/master/devel/libvirt/Makefile
>
> * Gentoo
> https://github.com/gentoo/gentoo/blob/master/app-emulation/libvirt/libvirt-5.1.0.ebuild#L296-L297
>
> * macOS (Homebrew)
> https://github.com/Homebrew/homebrew-core/blob/master/Formula/libvirt.rb
>
> * OpenSUSE
> https://build.opensuse.org/package/view_file/openSUSE:Leap:15.0:Update/libvirt/libvirt.spec?expand=1
>
> * Ubuntu
> https://git.launchpad.net/ubuntu/+source/libvirt/tree/debian/rules?h=ubuntu/disco#n99
>
> * Upstream :)
> https://libvirt.org/git/?p=libvirt.git;a=blob;f=libvirt.spec.in;h=b7a35a0fb14f3360eb795c4ec9b0e46171d2e4ec;hb=HEAD#l196
>
> m4/virt-driver-qemu.m4 | 30 ++++++++++++++++++++++++++++--
> 1 file changed, 28 insertions(+), 2 deletions(-)
>
> diff --git a/m4/virt-driver-qemu.m4 b/m4/virt-driver-qemu.m4
> index cb05c34265..5d4ac66a4b 100644
> --- a/m4/virt-driver-qemu.m4
> +++ b/m4/virt-driver-qemu.m4
> @@ -44,8 +44,34 @@ AC_DEFUN([LIBVIRT_DRIVER_CHECK_QEMU], [
> default_qemu_user=root
> default_qemu_group=wheel
> else
> - default_qemu_user=root
> - default_qemu_group=root
Either this needs to stay....
> + # Try to integrate gracefully with downstream packages by running QEMU
> + # processes under the same user and group they would
> + case $(grep ^ID= /etc/os-release 2>/dev/null) in
> + *arch*)
> + default_qemu_user=nobody
> + default_qemu_group=nobody
> + ;;
> + *centos*|*fedora*|*gentoo*|*rhel*|*suse*)
> + default_qemu_user=qemu
> + default_qemu_group=qemu
> + ;;
> + *debian*)
> + default_qemu_user=libvirt-qemu
> + default_qemu_group=libvirt-qemu
> + ;;
> + *ubuntu*)
> + default_qemu_user=libvirt-qemu
> + default_qemu_group=kvm
> + ;;
Or this needs to gain...
*)
default_qemu_user=root
default_qemu_group=root
> + esac
> + # If the expected user and group don't exist, or we haven't hit any
> + # of the cases above because we're running on an unknown OS, the only
> + # sensible fallback is root:root
> + if ! getent passwd "$default_qemu_user" >/dev/null 2>&1 || \
> + ! getent group "$default_qemu_group" >/dev/null 2>&1; then
otherwise these are passing an empty string to getent which
feels dubious. Even if empty string works I wouldn't want to
rely on that.
> + default_qemu_user=root
> + default_qemu_group=root
We ought to issue a warning if the expected user/group doesn't
actually exist.
> + fi
> fi
>
> if test "x$with_qemu_user" = "xplatform dependent" ; then
Regards,
Daniel
--
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On Tue, 2019-03-26 at 16:20 +0000, Daniel P. Berrangé wrote: > On Tue, Mar 26, 2019 at 05:06:15PM +0100, Andrea Bolognani wrote: > > + # Try to integrate gracefully with downstream packages by running QEMU > > + # processes under the same user and group they would > > + case $(grep ^ID= /etc/os-release 2>/dev/null) in > > + *arch*) > > + default_qemu_user=nobody > > + default_qemu_group=nobody > > + ;; > > + *centos*|*fedora*|*gentoo*|*rhel*|*suse*) > > + default_qemu_user=qemu > > + default_qemu_group=qemu > > + ;; > > + *debian*) > > + default_qemu_user=libvirt-qemu > > + default_qemu_group=libvirt-qemu > > + ;; > > + *ubuntu*) > > + default_qemu_user=libvirt-qemu > > + default_qemu_group=kvm > > + ;; > > Or this needs to gain... > > *) > default_qemu_user=root > default_qemu_group=root > > > + if ! getent passwd "$default_qemu_user" >/dev/null 2>&1 || \ > > + ! getent group "$default_qemu_group" >/dev/null 2>&1; then > > otherwise these are passing an empty string to getent which > feels dubious. Even if empty string works I wouldn't want to > rely on that. A (quoted) empty string work exactly the way you'd expect it to, in that it will make the command fail every single time. But sure, I can do the more obviously correct thing and add the default case above if you prefer that :) > > + default_qemu_user=root > > + default_qemu_group=root > > We ought to issue a warning if the expected user/group doesn't > actually exist. You got it. v3 coming right up. -- Andrea Bolognani / Red Hat / Virtualization -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
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