On Mon, May 6, 2024 at 1:21 PM Thomas Huth <thuth@xxxxxxxxxx> wrote:
>
> The old "-runas" option has the disadvantage that it is not visible
> in the QAPI schema, so it is not available via the normal introspection
> mechanisms. We've recently introduced the "-run-with" option for exactly
> this purpose, which is meant to handle the options that affect the
> runtime behavior. Thus let's introduce a "user=..." parameter here now
> and deprecate the old "-runas" option.
No need to deprecate it, there are other shortcut options that are
just a couple lines of code to implement:
case QEMU_OPTION_watchdog_action: {
opts = qemu_opts_create(qemu_find_opts("action"),
NULL, 0, &error_abort);
qemu_opt_set(opts, "watchdog", optarg, &error_abort);
break;
However that would be a larger patch, basically moving all of the
--run-with handling to qemu_process_early_options() (and, as an aside,
setting .merge_lists = true in qemu_run_with_opts).
No objections to your patch, but also no objections to cleaning all of
--run-with; I should have caught it and proposed the shortcut options
when it was introduced or when --chroot was removed.
Paolo
> if (!os_set_runas(optarg)) {
> error_report("User \"%s\" doesn't exist"
> " (and is not <uid>:<gid>)",
> @@ -3612,6 +3617,16 @@ void qemu_init(int argc, char **argv)
> if (str) {
> os_set_chroot(str);
> }
> + str = qemu_opt_get(opts, "user");
> + if (str) {
> + if (!os_set_runas(str)) {
> + error_report("User \"%s\" doesn't exist"
> + " (and is not <uid>:<gid>)",
> + optarg);
> + exit(1);
> + }
> + }
> +
> break;
> }
> #endif /* CONFIG_POSIX */
> diff --git a/qemu-options.hx b/qemu-options.hx
> index cf61f6b863..3031479a15 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -4824,7 +4824,8 @@ DEF("runas", HAS_ARG, QEMU_OPTION_runas, \
> SRST
> ``-runas user``
> Immediately before starting guest execution, drop root privileges,
> - switching to the specified user.
> + switching to the specified user. This option is deprecated, use
> + ``-run-with user=...`` instead.
> ERST
>
> DEF("prom-env", HAS_ARG, QEMU_OPTION_prom_env,
> @@ -4990,13 +4991,15 @@ DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL)
>
> #ifdef CONFIG_POSIX
> DEF("run-with", HAS_ARG, QEMU_OPTION_run_with,
> - "-run-with [async-teardown=on|off][,chroot=dir]\n"
> + "-run-with [async-teardown=on|off][,chroot=dir][user=username|uid:gid]\n"
> " Set miscellaneous QEMU process lifecycle options:\n"
> " async-teardown=on enables asynchronous teardown (Linux only)\n"
> - " chroot=dir chroot to dir just before starting the VM\n",
> + " chroot=dir chroot to dir just before starting the VM\n"
> + " user=username switch to the specified user before starting the VM\n"
> + " user=uid:gid dito, but use specified user-ID and group-ID instead\n",
> QEMU_ARCH_ALL)
> SRST
> -``-run-with [async-teardown=on|off][,chroot=dir]``
> +``-run-with [async-teardown=on|off][,chroot=dir][user=username|uid:gid]``
> Set QEMU process lifecycle options.
>
> ``async-teardown=on`` enables asynchronous teardown. A new process called
> @@ -5013,6 +5016,10 @@ SRST
> ``chroot=dir`` can be used for doing a chroot to the specified directory
> immediately before starting the guest execution. This is especially useful
> in combination with -runas.
> +
> + ``user=username`` or ``user=uid:gid`` can be used to drop root privileges
> + by switching to the specified user (via username) or user and group
> + (via uid:gid) immediately before starting guest execution.
> ERST
> #endif
>
> --
> 2.45.0
>M
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