Re: [PATCH v8] run QEMU as non-root

[Ian Campbell <ian.campbell@citrix.com>]

On Wed, 2015-09-30 at 16:45 +0100, Stefano Stabellini wrote:

> QEMU is going to setuid and setgid to the user ID and the group ID of
> the specified user, soon after initialization, before starting to deal
> with any guest IO.

Can you confirm that QEMU will bail if the user given via -runas doesn't
exist. IOW if the user gives b_info->device_model_user != NULL we will
correctly end up bailing if that specific user doesn't exist rather than
running as root?

If that is the case then:

Acked-by: Ian Campbell <ian.campbell@citrix.com>

Wasn't there some code to plumb this into xl at one point? Did that get
dropped along the way?

> [...]
> +        user = NULL;
> +        LOG(WARN, "Could not find user %s, starting QEMU as root",
> +            LIBXL_QEMU_USER_SHARED);
> +
> +end_search:
> +        if (user != NULL && strcmp(user, "root")) {

This strcmp struck me as odd given the user = NULL just above, but this is
for the case where the user explicitly requested root, right?

> +            flexarray_append(dm_args, "-runas");
> +            flexarray_append(dm_args, user);
> +        }