[libvirt] [PATCH] qemu: Actually unshare() iff running as root

[Richard W.M. Jones]

On Tue, Jan 17, 2017 at 12:32:16PM +0100, Michal Privoznik wrote:
> While all the code that deals with qemu namespaces correctly
> detects whether we are running as root (and turn into NO-OP for
> qemu:///session) the actual unshare() call is not guarded with
> such check. Therefore any attempt to start a domain under
> qemu:///session shall fail as unshare() is reserved for root.
> 
> The fix consists of moving unshare() call (for which we have a
> wrapper called virProcessSetupPrivateMountNS) into
> qemuDomainBuildNamespace() where the proper check is performed.
> 
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---
>  src/qemu/qemu_domain.c  | 3 +++
>  src/qemu/qemu_process.c | 3 ---
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
> index 35baffb51..c67604222 100644
> --- a/src/qemu/qemu_domain.c
> +++ b/src/qemu/qemu_domain.c
> @@ -7400,6 +7400,9 @@ qemuDomainBuildNamespace(virQEMUDriverPtr driver,
>          goto cleanup;
>      }
>  
> +    if (virProcessSetupPrivateMountNS() < 0)
> +        goto cleanup;
> +
>      if (qemuDomainSetupDev(driver, vm, devPath) < 0)
>          goto cleanup;
>  
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index a980f5a9e..184440dc1 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -2663,9 +2663,6 @@ static int qemuProcessHook(void *data)
>      if (virSecurityManagerClearSocketLabel(h->driver->securityManager, h->vm->def) < 0)
>          goto cleanup;
>  
> -    if (virProcessSetupPrivateMountNS() < 0)
> -        goto cleanup;
> -
>      if (qemuDomainBuildNamespace(h->driver, h->vm) < 0)
>          goto cleanup;

Tested-by: Richard W.M. Jones <rjones at redhat.com>

The commit message should also refer to the bug:
https://bugzilla.redhat.com/show_bug.cgi?id=1413922

Please make sure this bug blocks the release of 3.0.0.

Thanks,
Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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