[libvirt] [PATCH RFC] qemu: caps: Don't try to ask for CAP_DAC_OVERRIDE if non-root

[Erik Skultety]

On Mon, Feb 04, 2019 at 04:26:02PM +0100, Peter Krempa wrote:
> It will not work. This breaks qemu capabilities probing as a user.
> ---
>  src/qemu/qemu_capabilities.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
> index 7ed5f94803..81ef0357e7 100644
> --- a/src/qemu/qemu_capabilities.c
> +++ b/src/qemu/qemu_capabilities.c
> @@ -4524,7 +4524,8 @@ virQEMUCapsInitQMPCommandRun(virQEMUCapsInitQMPCommandPtr cmd,
>  #if WITH_CAPNG
>      /* QEMU might run into permission issues, e.g. /dev/sev (0600), override
>       * them just for the purpose of probing */
> -    virCommandAllowCap(cmd->cmd, CAP_DAC_OVERRIDE);
> +    if (geteuid() == 0)
> +        virCommandAllowCap(cmd->cmd, CAP_DAC_OVERRIDE);

This should be enough of a fix with the current code base as it won't clash with
the other two CAP_SYS_RAWIO and CAP_NET_ADMIN which should still fail when used
with the session daemon as expected.

Reviewed-by: Erik Skultety <eskultet at redhat.com>