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Re: [Qemu-devel] [Qemu-ppc] [PATCH v3] ppc: add host-serial and host-mod
From: |
Greg Kurz |
Subject: |
Re: [Qemu-devel] [Qemu-ppc] [PATCH v3] ppc: add host-serial and host-model machine attributes |
Date: |
Mon, 18 Feb 2019 12:38:11 +0100 |
On Mon, 18 Feb 2019 15:42:18 +0530
P J P <address@hidden> wrote:
> From: Prasad J Pandit <address@hidden>
>
> On ppc hosts, hypervisor shares following system attributes
>
> - /proc/device-tree/system-id
> - /proc/device-tree/model
>
> with a guest. This could lead to information leakage and misuse.[*]
> Add machine attributes to control such system information exposure
> to a guest.
>
> [*] https://wiki.openstack.org/wiki/OSSN/OSSN-0028
>
> Reported-by: Daniel P. Berrangé <address@hidden>
> Fix-suggested-by: Daniel P. Berrangé <address@hidden>
> Signed-off-by: Prasad J Pandit <address@hidden>
> ---
> hw/ppc/spapr.c | 79 ++++++++++++++++++++++++++++++++++++++----
> include/hw/ppc/spapr.h | 2 ++
> 2 files changed, 75 insertions(+), 6 deletions(-)
>
> Update v3: move host-serial,host-model options to ppc sPAPR machine
> -> https://lists.gnu.org/archive/html/qemu-devel/2019-02/msg03182.html
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 0942f35bf8..666e500376 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1249,13 +1249,30 @@ static void *spapr_build_fdt(sPAPRMachineState *spapr,
> * Add info to guest to indentify which host is it being run on
> * and what is the uuid of the guest
> */
> - if (kvmppc_get_host_model(&buf)) {
> - _FDT(fdt_setprop_string(fdt, 0, "host-model", buf));
> - g_free(buf);
> + 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 (kvmppc_get_host_serial(&buf)) {
> - _FDT(fdt_setprop_string(fdt, 0, "host-serial", buf));
> - g_free(buf);
> +
> + 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));
> + }
> }
>
> buf = qemu_uuid_unparse_strdup(&qemu_uuid);
> @@ -3138,6 +3155,36 @@ static void spapr_set_ic_mode(Object *obj, const char
> *value, Error **errp)
> }
> }
>
> +static char *spapr_get_host_model(Object *obj, Error **errp)
> +{
> + sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
> +
> + return g_strdup(spapr->host_model);
> +}
> +
> +static void spapr_set_host_model(Object *obj, const char *value, Error
> **errp)
> +{
> + sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
> +
> + g_free(spapr->host_model);
> + spapr->host_model = g_strdup(value);
> +}
> +
> +static char *spapr_get_host_serial(Object *obj, Error **errp)
> +{
> + sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
> +
> + return g_strdup(spapr->host_serial);
> +}
> +
> +static void spapr_set_host_serial(Object *obj, const char *value, Error
> **errp)
> +{
> + sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
> +
> + g_free(spapr->host_serial);
> + spapr->host_serial = g_strdup(value);
> +}
> +
> static void spapr_instance_init(Object *obj)
> {
> sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
> @@ -3183,6 +3230,20 @@ static void spapr_instance_init(Object *obj)
> object_property_set_description(obj, "ic-mode",
> "Specifies the interrupt controller mode (xics, xive,
> dual)",
> NULL);
> +
> + spapr->host_model = NULL;
This isn't needed since object_initialize_with_type() already takes care
of zeroing the instance for us.
> + object_property_add_str(obj, "host-model",
> + 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);
> +
> + spapr->host_serial = NULL;
Same here.
> + 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);
> }
>
> static void spapr_machine_finalizefn(Object *obj)
> @@ -4080,9 +4141,15 @@ DEFINE_SPAPR_MACHINE(4_0, "4.0", true);
> static void spapr_machine_3_1_class_options(MachineClass *mc)
> {
> sPAPRMachineClass *smc = SPAPR_MACHINE_CLASS(mc);
> + static GlobalProperty compat[] = {
> + { TYPE_SPAPR_MACHINE, "host-model", "passthrough" },
> + { TYPE_SPAPR_MACHINE, "host-serial", "passthrough" },
> + };
>
So... we don't fix the information leak for older machines by default ? From
previous discussions, I understand it is for the sake of compatibility, but
leaving the burden of securing the host to downstream or to the user still
looks unsecure to me FWIW.
> spapr_machine_4_0_class_options(mc);
> compat_props_add(mc->compat_props, hw_compat_3_1, hw_compat_3_1_len);
> + compat_props_add(mc->compat_props, compat, G_N_ELEMENTS(compat));
> +
> mc->default_cpu_type = POWERPC_CPU_TYPE_NAME("power8_v2.0");
> smc->update_dt_enabled = false;
> }
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index a947a0a0dc..e004a570d8 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -177,6 +177,8 @@ struct sPAPRMachineState {
>
> /*< public >*/
> char *kvm_type;
> + char *host_model;
> + char *host_serial;
>
> const char *icp_type;
> int32_t irq_map_nr;