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qemu.20428
0049-spapr-Simplify-handling-of-host-ser.patch
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File 0049-spapr-Simplify-handling-of-host-ser.patch of Package qemu.20428
From: David Gibson <david@gibson.dropbear.id.au> Date: Wed, 27 Mar 2019 13:54:11 +1100 Subject: spapr: Simplify handling of host-serial and host-model values MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 27461d69a0f "ppc: add host-serial and host-model machine attributes (CVE-2019-8934)" introduced 'host-serial' and 'host-model' machine properties for spapr to explicitly control the values advertised to the guest in device tree properties with the same names. The previous behaviour on KVM was to unconditionally populate the device tree with the real host serial number and model, which leaks possibly sensitive information about the host to the guest. To maintain compatibility for old machine types, we allowed those props to be set to "passthrough" to take the value from the host as before. Or they could be set to "none" to explicitly omit the device tree items. Special casing specific values on what's otherwise a user supplied string is very ugly. So, this patch simplifies things by implementing the backwards compatibility in a different way: we have a machine class flag set for the older machines, and we only load the host values into the device tree if A) they're not set by the user and B) we have that flag set. This does mean that the "passthrough" functionality is no longer available with the current machine type. That's ok though: if a user or management layer really wants the information passed through they can read it themselves (OpenStack Nova already does something similar for x86). It also means the user can't explicitly ask for the values to be omitted on the old machine types. I think that's an acceptable trade-off: if you care enough about not leaking the host information you can either move to the new machine type, or use a dummy value for the properties. For the new machine type, this also removes an odd inconsistency between running on a POWER and non-POWER (or non-Linux) hosts: if the host information couldn't be read from where we expect (in the host's device tree as exposed by Linux), we'd fallback to omitting the guest device tree items. While we're there, improve some poorly worded comments, and the help text for the properties. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Greg Kurz <groug@kaod.org> Tested-by: Greg Kurz <groug@kaod.org> (cherry picked from commit 0a794529bd1109aeea0c407784b40a2605e808b9) [BR: BSC#1126455 CVE-2019-03812] Signed-off-by: Bruce Rogers <brogers@suse.com> --- hw/ppc/spapr.c | 56 +++++++++++++++--------------------------- include/hw/ppc/spapr.h | 1 + 2 files changed, 21 insertions(+), 36 deletions(-) diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index d3098d520e12543724b342a012b7..b60e1702fcd8a66dc82db0c1b43d 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -1240,38 +1240,8 @@ static void *spapr_build_fdt(sPAPRMachineState *spapr, _FDT(fdt_setprop_string(fdt, 0, "model", "IBM pSeries (emulated by qemu)")); _FDT(fdt_setprop_string(fdt, 0, "compatible", "qemu,pseries")); - /* - * Add info to guest to indentify which host is it being run on - * and what is the uuid of the guest - */ - if (spapr->host_model && !g_str_equal(spapr->host_model, "none")) { - if (g_str_equal(spapr->host_model, "passthrough")) { - /* -M host-model=passthrough */ - if (kvmppc_get_host_model(&buf)) { - _FDT(fdt_setprop_string(fdt, 0, "host-model", buf)); - g_free(buf); - } - } else { - /* -M host-model=<user-string> */ - _FDT(fdt_setprop_string(fdt, 0, "host-model", spapr->host_model)); - } - } - - if (spapr->host_serial && !g_str_equal(spapr->host_serial, "none")) { - if (g_str_equal(spapr->host_serial, "passthrough")) { - /* -M host-serial=passthrough */ - if (kvmppc_get_host_serial(&buf)) { - _FDT(fdt_setprop_string(fdt, 0, "host-serial", buf)); - g_free(buf); - } - } else { - /* -M host-serial=<user-string> */ - _FDT(fdt_setprop_string(fdt, 0, "host-serial", spapr->host_serial)); - } - } - + /* Guest UUID & Name*/ buf = qemu_uuid_unparse_strdup(&qemu_uuid); - _FDT(fdt_setprop_string(fdt, 0, "vm,uuid", buf)); if (qemu_uuid_set) { _FDT(fdt_setprop_string(fdt, 0, "system-id", buf)); @@ -1283,6 +1253,21 @@ static void *spapr_build_fdt(sPAPRMachineState *spapr, qemu_get_vm_name())); } + /* Host Model & Serial Number */ + if (spapr->host_model) { + _FDT(fdt_setprop_string(fdt, 0, "host-model", spapr->host_model)); + } else if (smc->broken_host_serial_model && kvmppc_get_host_model(&buf)) { + _FDT(fdt_setprop_string(fdt, 0, "host-model", buf)); + g_free(buf); + } + + if (spapr->host_serial) { + _FDT(fdt_setprop_string(fdt, 0, "host-serial", spapr->host_serial)); + } else if (smc->broken_host_serial_model && kvmppc_get_host_serial(&buf)) { + _FDT(fdt_setprop_string(fdt, 0, "host-serial", buf)); + g_free(buf); + } + _FDT(fdt_setprop_cell(fdt, 0, "#address-cells", 2)); _FDT(fdt_setprop_cell(fdt, 0, "#size-cells", 2)); @@ -3119,12 +3104,12 @@ static void spapr_instance_init(Object *obj) spapr_get_host_model, spapr_set_host_model, &error_abort); object_property_set_description(obj, "host-model", - "Set host's model-id to use - none|passthrough|string", &error_abort); + "Host model to advertise in guest device tree", &error_abort); object_property_add_str(obj, "host-serial", spapr_get_host_serial, spapr_set_host_serial, &error_abort); object_property_set_description(obj, "host-serial", - "Set host's system-id to use - none|passthrough|string", &error_abort); + "Host serial number to advertise in guest device tree", &error_abort); } static void spapr_machine_finalizefn(Object *obj) @@ -4019,14 +4004,13 @@ static const TypeInfo spapr_machine_info = { */ static void spapr_machine_3_1_instance_options(MachineState *machine) { - sPAPRMachineState *spapr = SPAPR_MACHINE(machine); - spapr->host_model = g_strdup("passthrough"); - spapr->host_serial = g_strdup("passthrough"); } static void spapr_machine_3_1_class_options(MachineClass *mc) { /* Defaults for the latest behaviour inherited from the base class */ + sPAPRMachineClass *smc = SPAPR_MACHINE_CLASS(mc); + smc->broken_host_serial_model = true; } DEFINE_SPAPR_MACHINE(3_1, "3.1", true); diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h index 63692a13bd5ef7e42855dabb7622..d3142e0d26204fab06a38cee698d 100644 --- a/include/hw/ppc/spapr.h +++ b/include/hw/ppc/spapr.h @@ -105,6 +105,7 @@ struct sPAPRMachineClass { bool use_ohci_by_default; /* use USB-OHCI instead of XHCI */ bool pre_2_10_has_unused_icps; bool legacy_irq_allocation; + bool broken_host_serial_model; /* present real host info to the guest */ void (*phb_placement)(sPAPRMachineState *spapr, uint32_t index, uint64_t *buid, hwaddr *pio,
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