On Mon, Oct 25, 2021 at 04:53:57PM +0200, Alexander Graf wrote:
On 25.10.21 16:47, Daniel P. Berrangé wrote:
On Mon, Oct 25, 2021 at 04:42:22PM +0200, Alexander Graf wrote:
On 25.10.21 16:22, Daniel P. Berrangé wrote:
On Mon, Oct 25, 2021 at 12:13:32PM +0200, Alexander Graf wrote:
On 22.10.21 18:14, Vladislav Yaroshchuk wrote:
On Apple hosts we can read AppleSMC OSK key directly from host's
SMC and forward this value to QEMU Guest.
Usage:
`-device isa-applesmc,hostosk=on`
Apple licence allows use and run up to two additional copies
or instances of macOS operating within virtual operating system
environments on each Apple-branded computer that is already running
the Apple Software, for purposes of:
- software development
- testing during software development
- using macOS Server
- personal, non-commercial use
Guest macOS requires AppleSMC with correct OSK. The most legal
way to pass it to the Guest is to forward the key from host SMC
without any value exposion.
Based on
https://web.archive.org/web/20200103161737/osxbook.com/book/bonus/chapter7/tpmdrmmyth/
Signed-off-by: Vladislav Yaroshchuk <yaroshchuk2000@gmail.com>
@@ -331,6 +464,25 @@ static void applesmc_isa_realize(DeviceState *dev, Error
**errp)
isa_register_ioport(&s->parent_obj, &s->io_err,
s->iobase + APPLESMC_ERR_PORT);
+ if (s->hostosk_flag) {
+ /*
+ * Property 'hostosk' has higher priority than 'osk'
+ * and shadows it.
+ * Free user-provided 'osk' property value
+ */
+ if (s->osk) {
+ warn_report("isa-applesmc.osk is shadowed "
+ "by isa-applesmc.hostosk");
+ g_free(s->osk);
+ }
+
+ if (!applesmc_read_host_osk(&s->osk, &err)) {
+ /* On host OSK retrieval error report a warning */
+ error_report_err(err);
+ s->osk = default_osk;
+ }
+ }
This part is yucky. A few things:
1) QEMU in general does not fail user requested operations silently. If the
user explicitly asked to read the host OSK and we couldn't, it must
propagate that error.
2) In tandem to the above, I think the only consistent CX is to make both
options mutually exclusive. The easiest way to achieve that IMHO would be to
overload the "osk" property. If it is "host", then use the host one.
3) Should we make "osk"="host" the default on macOS as well then? Of course,
that one should *not* fail hard when it can't read the key, because it's an
implicit request rather than an explicit one.
The problem with using a magic string value for the existing "osk"
parameter is that this is not introspectable by management apps.
What introspectability would you like to have?
Essentially to answer the question
"Does this QEMU support OSK passthrough from the host"
Mgmt apps like libvirt introspect using various query-XXX QMP commands.
For devices, the typical approach is to ask for the list of properties
the device supports. If we're just accepting a new magic value on an
existing property there is no way to query for existance of that feature.
If we add a "host-osk=bool" parameter introspectability is trivially
satisfied.
Ok, the only flow that remains sensible in that case to me sounds like the
following:
Just need an extra check upfront:
if (s->osk && s->use_hoist_osk)
error_setg(errp, ...)
else
if (s->osk) {
/* Use osk */
This should fail hard if the provided value is the wrong length - currently
it falls back with a warning IIUC.
} else if (s->use_host_osk) {
/* Use host OSK. Fail hard if we can't find it */
} else if (can_use_host_osk) {
/* See if we can extract the key from the host. If not, fall back to old
behavior */
} else {
/* Old fallback behavior */
Was this old fallback behaviour actually useful ? IIUC it means it is using
static char default_osk[64] = "This is a dummy key. Enter the real key "
"using the -osk parameter";
which obviously isn't a valid key that will work with any gust OS that
cares. I guess it at least let QEMU startup, but any the guest OS that
checks the key will be unhappy.
If if don't think default_osk is actually useful, then we could simplify
further to
if (s->osk && s->use_host_osk) {
error_setg(errp, ...)
} else if (s->osk) {
/* Use osk. Fail hard if invalid (ie wrong length) */
} else if (s->use_host_osk) {
/* Use host OSK. Fail hard if we can't find it */
} else {
/* try to use host OSK, fail hard if we can't find it or non-OS-X build */
}