xen/arch/arm/hvm.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 62 insertions(+), 3 deletions(-)
ARM currently has no restrictions on toolstack and guest access to the entire
HVM_PARAM block. As the paging/monitor/sharing features aren't under security
support, this doesn't need an XSA.
The CALLBACK_IRQ and {STORE,CONSOLE}_{PFN,EVTCHN} details exposed read-only to
the guest, while the *_RING_PFN details are restricted to only toolstack
access. No other parameters are used.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Julien Grall <julien@xen.org>
CC: Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
This is only compile tested, and based on my reading of the source. There
might be other PARAMS needing including.
---
xen/arch/arm/hvm.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 62 insertions(+), 3 deletions(-)
diff --git a/xen/arch/arm/hvm.c b/xen/arch/arm/hvm.c
index 76b27c9168..1446d4010c 100644
--- a/xen/arch/arm/hvm.c
+++ b/xen/arch/arm/hvm.c
@@ -31,6 +31,60 @@
#include <asm/hypercall.h>
+static int hvm_allow_set_param(const struct domain *d, unsigned int param)
+{
+ switch ( param )
+ {
+ /*
+ * The following parameters are intended for toolstack usage only.
+ * They may not be set by the domain.
+ *
+ * The {STORE,CONSOLE}_EVTCHN values will need to become read/write if
+ * a new ABI hasn't appeared by the time migration support is added.
+ */
+ case HVM_PARAM_CALLBACK_IRQ:
+ case HVM_PARAM_STORE_PFN:
+ case HVM_PARAM_STORE_EVTCHN:
+ case HVM_PARAM_CONSOLE_PFN:
+ case HVM_PARAM_CONSOLE_EVTCHN:
+ case HVM_PARAM_PAGING_RING_PFN:
+ case HVM_PARAM_MONITOR_RING_PFN:
+ case HVM_PARAM_SHARING_RING_PFN:
+ return d == current->domain ? -EPERM : 0;
+
+ /* Writeable only by Xen, hole, deprecated, or out-of-range. */
+ default:
+ return -EINVAL;
+ }
+}
+
+static int hvm_allow_get_param(const struct domain *d, unsigned int param)
+{
+ switch ( param )
+ {
+ /* The following parameters can be read by the guest and toolstack. */
+ case HVM_PARAM_CALLBACK_IRQ:
+ case HVM_PARAM_STORE_PFN:
+ case HVM_PARAM_STORE_EVTCHN:
+ case HVM_PARAM_CONSOLE_PFN:
+ case HVM_PARAM_CONSOLE_EVTCHN:
+ return 0;
+
+ /*
+ * The following parameters are intended for toolstack usage only.
+ * They may not be read by the domain.
+ */
+ case HVM_PARAM_PAGING_RING_PFN:
+ case HVM_PARAM_MONITOR_RING_PFN:
+ case HVM_PARAM_SHARING_RING_PFN:
+ return d == current->domain ? -EPERM : 0;
+
+ /* Hole, deprecated, or out-of-range. */
+ default:
+ return -EINVAL;
+ }
+}
+
long do_hvm_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) arg)
{
long rc = 0;
@@ -46,9 +100,6 @@ long do_hvm_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) arg)
if ( copy_from_guest(&a, arg, 1) )
return -EFAULT;
- if ( a.index >= HVM_NR_PARAMS )
- return -EINVAL;
-
d = rcu_lock_domain_by_any_id(a.domid);
if ( d == NULL )
return -ESRCH;
@@ -59,10 +110,18 @@ long do_hvm_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) arg)
if ( op == HVMOP_set_param )
{
+ rc = hvm_allow_set_param(d, a.index);
+ if ( rc )
+ goto param_fail;
+
d->arch.hvm.params[a.index] = a.value;
}
else
{
+ rc = hvm_allow_get_param(d, a.index);
+ if ( rc )
+ goto param_fail;
+
a.value = d->arch.hvm.params[a.index];
rc = copy_to_guest(arg, &a, 1) ? -EFAULT : 0;
}
--
2.11.0
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-develOn Mon, Feb 10, 2020 at 11:46 AM Andrew Cooper <andrew.cooper3@citrix.com> wrote: > > ARM currently has no restrictions on toolstack and guest access to the entire > HVM_PARAM block. As the paging/monitor/sharing features aren't under security > support, this doesn't need an XSA. There is no paging or sharing implementation on ARM anyway. A cc would have been nice though. Thanks, Tamas _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
On 19/02/2020 16:44, Tamas K Lengyel wrote: > On Mon, Feb 10, 2020 at 11:46 AM Andrew Cooper > <andrew.cooper3@citrix.com> wrote: >> ARM currently has no restrictions on toolstack and guest access to the entire >> HVM_PARAM block. As the paging/monitor/sharing features aren't under security >> support, this doesn't need an XSA. > There is no paging or sharing implementation on ARM anyway. Great. > A cc would have been nice though. Sorry. I didn't consider this something other than "clean up the parameter handling". It was based on which parameters were referenced in common or arm specific code. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
Hi Andrew,
Thank you for stepping up and trying to make HVM_PARAM better :).
On 10/02/2020 18:45, Andrew Cooper wrote:
> ARM currently has no restrictions on toolstack and guest access to the entire
> HVM_PARAM block. As the paging/monitor/sharing features aren't under security
> support, this doesn't need an XSA.
Actually, only monitor is effectively working (yet not security
supported) on Arm. The two others are x86 specific.
>
> The CALLBACK_IRQ and {STORE,CONSOLE}_{PFN,EVTCHN} details exposed read-only to
> the guest, while the *_RING_PFN details are restricted to only toolstack
> access. No other parameters are used.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> ---
> CC: Stefano Stabellini <sstabellini@kernel.org>
> CC: Julien Grall <julien@xen.org>
> CC: Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
>
> This is only compile tested, and based on my reading of the source. There
> might be other PARAMS needing including.
> ---
> xen/arch/arm/hvm.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 62 insertions(+), 3 deletions(-)
>
> diff --git a/xen/arch/arm/hvm.c b/xen/arch/arm/hvm.c
> index 76b27c9168..1446d4010c 100644
> --- a/xen/arch/arm/hvm.c
> +++ b/xen/arch/arm/hvm.c
> @@ -31,6 +31,60 @@
>
> #include <asm/hypercall.h>
>
> +static int hvm_allow_set_param(const struct domain *d, unsigned int param)
> +{
Should we move the XSM check here too? This is not too important though.
> + switch ( param )
> + {
> + /*
> + * The following parameters are intended for toolstack usage only.
> + * They may not be set by the domain.
> + *
> + * The {STORE,CONSOLE}_EVTCHN values will need to become read/write if
> + * a new ABI hasn't appeared by the time migration support is added.
The comment suggests {STORE, CONSOLE}_EVTCHN values should not be
read/write. But you implement them as read/write. Is it intended?
> + */
> + case HVM_PARAM_CALLBACK_IRQ:
> + case HVM_PARAM_STORE_PFN:
> + case HVM_PARAM_STORE_EVTCHN:
> + case HVM_PARAM_CONSOLE_PFN:
> + case HVM_PARAM_CONSOLE_EVTCHN:
> + case HVM_PARAM_PAGING_RING_PFN:
> + case HVM_PARAM_MONITOR_RING_PFN:
> + case HVM_PARAM_SHARING_RING_PFN:
I would drop HVM_PARAM_PAGING_RING_PFN and HVM_PARAM_SHARING_RING_PFN as
they are not used by Arm and AFAICT the toolstack will not set them.
> + return d == current->domain ? -EPERM : 0;
> +
Looking at the list of HVM param, I think you forgot to add
HVM_PARAM_VM_GENERATION_ID_ADDR.
> + /* Writeable only by Xen, hole, deprecated, or out-of-range. */
> + default:
> + return -EINVAL;
> + }
> +}
Cheers,
--
Julien Grall
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
On 19/02/2020 15:53, Julien Grall wrote:
>> diff --git a/xen/arch/arm/hvm.c b/xen/arch/arm/hvm.c
>> index 76b27c9168..1446d4010c 100644
>> --- a/xen/arch/arm/hvm.c
>> +++ b/xen/arch/arm/hvm.c
>> @@ -31,6 +31,60 @@
>> #include <asm/hypercall.h>
>> +static int hvm_allow_set_param(const struct domain *d, unsigned
>> int param)
>> +{
>
> Should we move the XSM check here too? This is not too important though.
Currently there is a single XSM call, before the get/set split. Moving
it in here would create two.
i.e. the current way compiles smaller and will run (fractionally) faster.
>
>> + switch ( param )
>> + {
>> + /*
>> + * The following parameters are intended for toolstack usage
>> only.
>> + * They may not be set by the domain.
>> + *
>> + * The {STORE,CONSOLE}_EVTCHN values will need to become
>> read/write if
>> + * a new ABI hasn't appeared by the time migration support
>> is added.
>
> The comment suggests {STORE, CONSOLE}_EVTCHN values should not be
> read/write. But you implement them as read/write. Is it intended?
It is currently read/write only to !SELF (i.e. only the toolstack or
qemu stub).
If it needs to change in the future, it needs to become a separate block
in the switch statement which returns 0 straight away.
Would "read/write to the guest if" be clearer in the comment?
>
>> + */
>> + case HVM_PARAM_CALLBACK_IRQ:
>> + case HVM_PARAM_STORE_PFN:
>> + case HVM_PARAM_STORE_EVTCHN:
>> + case HVM_PARAM_CONSOLE_PFN:
>> + case HVM_PARAM_CONSOLE_EVTCHN:
>> + case HVM_PARAM_PAGING_RING_PFN:
>> + case HVM_PARAM_MONITOR_RING_PFN:
>> + case HVM_PARAM_SHARING_RING_PFN:
>
> I would drop HVM_PARAM_PAGING_RING_PFN and HVM_PARAM_SHARING_RING_PFN
> as they are not used by Arm and AFAICT the toolstack will not set them.
Even better.
>
>> + return d == current->domain ? -EPERM : 0;
>> +
>
> Looking at the list of HVM param, I think you forgot to add
> HVM_PARAM_VM_GENERATION_ID_ADDR.
It is a windows specific thing. The spec dates from a pre-ARM time, and
while there is nothing obviously x86-only, it does depend on the AML
(via the DSDT or an SSDT).
Either way, its only relevant for migration and/or revert-to-snapshot,
so is of no use to Xen on ARM at this point in time.
~Andrew
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
ARM currently has no restrictions on toolstack and guest access to the entire
HVM_PARAM block. As the monitor feature isn't under security support, this
doesn't need an XSA.
The CALLBACK_IRQ and {STORE,CONSOLE}_{PFN,EVTCHN} details are only exposed
read-only to the guest, while MONITOR_RING_PFN is restricted to only toolstack
access. No other parameters are used.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Julien Grall <julien@xen.org>
CC: Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
This is only compile tested, and based on my reading of the source. There
might be other PARAMS needing including.
v2:
* Drop paging/sharing
* Clarify comment about {STORE,CONSOLE}_EVTCHN
---
xen/arch/arm/hvm.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 59 insertions(+), 3 deletions(-)
diff --git a/xen/arch/arm/hvm.c b/xen/arch/arm/hvm.c
index 76b27c9168..8951b34086 100644
--- a/xen/arch/arm/hvm.c
+++ b/xen/arch/arm/hvm.c
@@ -31,6 +31,57 @@
#include <asm/hypercall.h>
+static int hvm_allow_set_param(const struct domain *d, unsigned int param)
+{
+ switch ( param )
+ {
+ /*
+ * The following parameters are intended for toolstack usage only.
+ * They may not be set by the domain.
+ *
+ * The {STORE,CONSOLE}_EVTCHN values will need to become read/write to
+ * the guest (not just the toolstack) if a new ABI hasn't appeared by
+ * the time migration support is added.
+ */
+ case HVM_PARAM_CALLBACK_IRQ:
+ case HVM_PARAM_STORE_PFN:
+ case HVM_PARAM_STORE_EVTCHN:
+ case HVM_PARAM_CONSOLE_PFN:
+ case HVM_PARAM_CONSOLE_EVTCHN:
+ case HVM_PARAM_MONITOR_RING_PFN:
+ return d == current->domain ? -EPERM : 0;
+
+ /* Writeable only by Xen, hole, deprecated, or out-of-range. */
+ default:
+ return -EINVAL;
+ }
+}
+
+static int hvm_allow_get_param(const struct domain *d, unsigned int param)
+{
+ switch ( param )
+ {
+ /* The following parameters can be read by the guest and toolstack. */
+ case HVM_PARAM_CALLBACK_IRQ:
+ case HVM_PARAM_STORE_PFN:
+ case HVM_PARAM_STORE_EVTCHN:
+ case HVM_PARAM_CONSOLE_PFN:
+ case HVM_PARAM_CONSOLE_EVTCHN:
+ return 0;
+
+ /*
+ * The following parameters are intended for toolstack usage only.
+ * They may not be read by the domain.
+ */
+ case HVM_PARAM_MONITOR_RING_PFN:
+ return d == current->domain ? -EPERM : 0;
+
+ /* Hole, deprecated, or out-of-range. */
+ default:
+ return -EINVAL;
+ }
+}
+
long do_hvm_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) arg)
{
long rc = 0;
@@ -46,9 +97,6 @@ long do_hvm_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) arg)
if ( copy_from_guest(&a, arg, 1) )
return -EFAULT;
- if ( a.index >= HVM_NR_PARAMS )
- return -EINVAL;
-
d = rcu_lock_domain_by_any_id(a.domid);
if ( d == NULL )
return -ESRCH;
@@ -59,10 +107,18 @@ long do_hvm_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) arg)
if ( op == HVMOP_set_param )
{
+ rc = hvm_allow_set_param(d, a.index);
+ if ( rc )
+ goto param_fail;
+
d->arch.hvm.params[a.index] = a.value;
}
else
{
+ rc = hvm_allow_get_param(d, a.index);
+ if ( rc )
+ goto param_fail;
+
a.value = d->arch.hvm.params[a.index];
rc = copy_to_guest(arg, &a, 1) ? -EFAULT : 0;
}
--
2.11.0
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Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-develHi Andrew,
On 19/02/2020 19:30, Andrew Cooper wrote:
> ARM currently has no restrictions on toolstack and guest access to the entire
> HVM_PARAM block. As the monitor feature isn't under security support, this
> doesn't need an XSA.
>
> The CALLBACK_IRQ and {STORE,CONSOLE}_{PFN,EVTCHN} details are only exposed
> read-only to the guest, while MONITOR_RING_PFN is restricted to only toolstack
> access. No other parameters are used.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Julien Grall <julien@xen.org>
Cheers,
> ---
> CC: Stefano Stabellini <sstabellini@kernel.org>
> CC: Julien Grall <julien@xen.org>
> CC: Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
>
> This is only compile tested, and based on my reading of the source. There
> might be other PARAMS needing including.
>
> v2:
> * Drop paging/sharing
> * Clarify comment about {STORE,CONSOLE}_EVTCHN
> ---
> xen/arch/arm/hvm.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 59 insertions(+), 3 deletions(-)
>
> diff --git a/xen/arch/arm/hvm.c b/xen/arch/arm/hvm.c
> index 76b27c9168..8951b34086 100644
> --- a/xen/arch/arm/hvm.c
> +++ b/xen/arch/arm/hvm.c
> @@ -31,6 +31,57 @@
>
> #include <asm/hypercall.h>
>
> +static int hvm_allow_set_param(const struct domain *d, unsigned int param)
> +{
> + switch ( param )
> + {
> + /*
> + * The following parameters are intended for toolstack usage only.
> + * They may not be set by the domain.
> + *
> + * The {STORE,CONSOLE}_EVTCHN values will need to become read/write to
> + * the guest (not just the toolstack) if a new ABI hasn't appeared by
> + * the time migration support is added.
> + */
> + case HVM_PARAM_CALLBACK_IRQ:
> + case HVM_PARAM_STORE_PFN:
> + case HVM_PARAM_STORE_EVTCHN:
> + case HVM_PARAM_CONSOLE_PFN:
> + case HVM_PARAM_CONSOLE_EVTCHN:
> + case HVM_PARAM_MONITOR_RING_PFN:
> + return d == current->domain ? -EPERM : 0;
> +
> + /* Writeable only by Xen, hole, deprecated, or out-of-range. */
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static int hvm_allow_get_param(const struct domain *d, unsigned int param)
> +{
> + switch ( param )
> + {
> + /* The following parameters can be read by the guest and toolstack. */
> + case HVM_PARAM_CALLBACK_IRQ:
> + case HVM_PARAM_STORE_PFN:
> + case HVM_PARAM_STORE_EVTCHN:
> + case HVM_PARAM_CONSOLE_PFN:
> + case HVM_PARAM_CONSOLE_EVTCHN:
> + return 0;
> +
> + /*
> + * The following parameters are intended for toolstack usage only.
> + * They may not be read by the domain.
> + */
> + case HVM_PARAM_MONITOR_RING_PFN:
> + return d == current->domain ? -EPERM : 0;
> +
> + /* Hole, deprecated, or out-of-range. */
> + default:
> + return -EINVAL;
> + }
> +}
> +
> long do_hvm_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) arg)
> {
> long rc = 0;
> @@ -46,9 +97,6 @@ long do_hvm_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) arg)
> if ( copy_from_guest(&a, arg, 1) )
> return -EFAULT;
>
> - if ( a.index >= HVM_NR_PARAMS )
> - return -EINVAL;
> -
> d = rcu_lock_domain_by_any_id(a.domid);
> if ( d == NULL )
> return -ESRCH;
> @@ -59,10 +107,18 @@ long do_hvm_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) arg)
>
> if ( op == HVMOP_set_param )
> {
> + rc = hvm_allow_set_param(d, a.index);
> + if ( rc )
> + goto param_fail;
> +
> d->arch.hvm.params[a.index] = a.value;
> }
> else
> {
> + rc = hvm_allow_get_param(d, a.index);
> + if ( rc )
> + goto param_fail;
> +
> a.value = d->arch.hvm.params[a.index];
> rc = copy_to_guest(arg, &a, 1) ? -EFAULT : 0;
> }
>
--
Julien Grall
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