* [Qemu-devel] [PATCH] virtio-blk: refuse SG_IO requests with scsi=off
@ 2011-12-23 14:39 Paolo Bonzini
2011-12-30 11:45 ` Stefan Hajnoczi
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: Paolo Bonzini @ 2011-12-23 14:39 UTC (permalink / raw)
To: qemu-devel
QEMU does have a "scsi" option (to be used like -device
virtio-blk-pci,drive=foo,scsi=off). However, it only
masks the feature bit, and does not reject the command
if a malicious guest disregards the feature bits and
issues a request.
Without this patch, using scsi=off does not protect you
from CVE-2011-4127.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
hw/virtio-blk.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index b70d116..6cd3164 100644
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -153,6 +153,12 @@ static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
int status;
int i;
+ if ((req->dev->vdev.guest_features & (1 << VIRTIO_BLK_F_SCSI)) == 0) {
+ virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
+ g_free(req);
+ return;
+ }
+
/*
* We require at least one output segment each for the virtio_blk_outhdr
* and the SCSI command block.
--
1.7.7.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [Qemu-devel] [PATCH] virtio-blk: refuse SG_IO requests with scsi=off
2011-12-23 14:39 [Qemu-devel] [PATCH] virtio-blk: refuse SG_IO requests with scsi=off Paolo Bonzini
@ 2011-12-30 11:45 ` Stefan Hajnoczi
2012-01-05 10:05 ` Paolo Bonzini
2012-01-13 16:54 ` Anthony Liguori
2 siblings, 0 replies; 5+ messages in thread
From: Stefan Hajnoczi @ 2011-12-30 11:45 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: qemu-devel
On Fri, Dec 23, 2011 at 03:39:03PM +0100, Paolo Bonzini wrote:
> QEMU does have a "scsi" option (to be used like -device
> virtio-blk-pci,drive=foo,scsi=off). However, it only
> masks the feature bit, and does not reject the command
> if a malicious guest disregards the feature bits and
> issues a request.
>
> Without this patch, using scsi=off does not protect you
> from CVE-2011-4127.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> hw/virtio-blk.c | 6 ++++++
> 1 files changed, 6 insertions(+), 0 deletions(-)
I checked that guest_features cannot have SCSI enabled when the host
wishes to prohibit SCSI.
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [Qemu-devel] [PATCH] virtio-blk: refuse SG_IO requests with scsi=off
2011-12-23 14:39 [Qemu-devel] [PATCH] virtio-blk: refuse SG_IO requests with scsi=off Paolo Bonzini
2011-12-30 11:45 ` Stefan Hajnoczi
@ 2012-01-05 10:05 ` Paolo Bonzini
2012-01-13 15:56 ` Paolo Bonzini
2012-01-13 16:54 ` Anthony Liguori
2 siblings, 1 reply; 5+ messages in thread
From: Paolo Bonzini @ 2012-01-05 10:05 UTC (permalink / raw)
To: qemu-devel
On 12/23/2011 03:39 PM, Paolo Bonzini wrote:
> QEMU does have a "scsi" option (to be used like -device
> virtio-blk-pci,drive=foo,scsi=off). However, it only
> masks the feature bit, and does not reject the command
> if a malicious guest disregards the feature bits and
> issues a request.
>
> Without this patch, using scsi=off does not protect you
> from CVE-2011-4127.
>
> Signed-off-by: Paolo Bonzini<pbonzini@redhat.com>
> ---
> hw/virtio-blk.c | 6 ++++++
> 1 files changed, 6 insertions(+), 0 deletions(-)
>
> diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
> index b70d116..6cd3164 100644
> --- a/hw/virtio-blk.c
> +++ b/hw/virtio-blk.c
> @@ -153,6 +153,12 @@ static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
> int status;
> int i;
>
> + if ((req->dev->vdev.guest_features& (1<< VIRTIO_BLK_F_SCSI)) == 0) {
> + virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
> + g_free(req);
> + return;
> + }
> +
> /*
> * We require at least one output segment each for the virtio_blk_outhdr
> * and the SCSI command block.
Ping.
Paolo
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [Qemu-devel] [PATCH] virtio-blk: refuse SG_IO requests with scsi=off
2012-01-05 10:05 ` Paolo Bonzini
@ 2012-01-13 15:56 ` Paolo Bonzini
0 siblings, 0 replies; 5+ messages in thread
From: Paolo Bonzini @ 2012-01-13 15:56 UTC (permalink / raw)
To: qemu-devel
On 01/05/2012 11:05 AM, Paolo Bonzini wrote:
> On 12/23/2011 03:39 PM, Paolo Bonzini wrote:
>> QEMU does have a "scsi" option (to be used like -device
>> virtio-blk-pci,drive=foo,scsi=off). However, it only
>> masks the feature bit, and does not reject the command
>> if a malicious guest disregards the feature bits and
>> issues a request.
>>
>> Without this patch, using scsi=off does not protect you
>> from CVE-2011-4127.
>>
>> Signed-off-by: Paolo Bonzini<pbonzini@redhat.com>
>> ---
>> hw/virtio-blk.c | 6 ++++++
>> 1 files changed, 6 insertions(+), 0 deletions(-)
>>
>> diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
>> index b70d116..6cd3164 100644
>> --- a/hw/virtio-blk.c
>> +++ b/hw/virtio-blk.c
>> @@ -153,6 +153,12 @@ static void virtio_blk_handle_scsi(VirtIOBlockReq
>> *req)
>> int status;
>> int i;
>>
>> + if ((req->dev->vdev.guest_features& (1<< VIRTIO_BLK_F_SCSI)) == 0) {
>> + virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
>> + g_free(req);
>> + return;
>> + }
>> +
>> /*
>> * We require at least one output segment each for the virtio_blk_outhdr
>> * and the SCSI command block.
>
> Ping.
Ping^2
Paolo
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [Qemu-devel] [PATCH] virtio-blk: refuse SG_IO requests with scsi=off
2011-12-23 14:39 [Qemu-devel] [PATCH] virtio-blk: refuse SG_IO requests with scsi=off Paolo Bonzini
2011-12-30 11:45 ` Stefan Hajnoczi
2012-01-05 10:05 ` Paolo Bonzini
@ 2012-01-13 16:54 ` Anthony Liguori
2 siblings, 0 replies; 5+ messages in thread
From: Anthony Liguori @ 2012-01-13 16:54 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: qemu-devel
On 12/23/2011 08:39 AM, Paolo Bonzini wrote:
> QEMU does have a "scsi" option (to be used like -device
> virtio-blk-pci,drive=foo,scsi=off). However, it only
> masks the feature bit, and does not reject the command
> if a malicious guest disregards the feature bits and
> issues a request.
>
> Without this patch, using scsi=off does not protect you
> from CVE-2011-4127.
>
> Signed-off-by: Paolo Bonzini<pbonzini@redhat.com>
Applied. Thanks.
Regards,
Anthony Liguori
> ---
> hw/virtio-blk.c | 6 ++++++
> 1 files changed, 6 insertions(+), 0 deletions(-)
>
> diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
> index b70d116..6cd3164 100644
> --- a/hw/virtio-blk.c
> +++ b/hw/virtio-blk.c
> @@ -153,6 +153,12 @@ static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
> int status;
> int i;
>
> + if ((req->dev->vdev.guest_features& (1<< VIRTIO_BLK_F_SCSI)) == 0) {
> + virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
> + g_free(req);
> + return;
> + }
> +
> /*
> * We require at least one output segment each for the virtio_blk_outhdr
> * and the SCSI command block.
^ permalink raw reply [flat|nested] 5+ messages in thread
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2011-12-23 14:39 [Qemu-devel] [PATCH] virtio-blk: refuse SG_IO requests with scsi=off Paolo Bonzini
2011-12-30 11:45 ` Stefan Hajnoczi
2012-01-05 10:05 ` Paolo Bonzini
2012-01-13 15:56 ` Paolo Bonzini
2012-01-13 16:54 ` Anthony Liguori
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