> > @@ -292,6 +292,9 @@ struct vmstorage_protocol_version {
> > #define STORAGE_CHANNEL_REMOVABLE_FLAG 0x1
> > #define STORAGE_CHANNEL_EMULATED_IDE_FLAG 0x2
> >
> > +/* Lower bound on the size of unsolicited packets with ID of 0 */
> > +#define VSTOR_MIN_UNSOL_PKT_SIZE 48
> > +
>
> I know you have determined experimentally that Hyper-V sends
> unsolicited packets with the above length, so the idea is to validate
> that the guest actually gets packets at least that big. But I wonder if
> we should think about this slightly differently.
>
> The goal is for the storvsc driver to protect itself against bad or
> malicious messages from Hyper-V. For the unsolicited messages, the
> only field that this storvsc driver needs to access is the
> vstor_packet->operation field.
Eh, this is one piece of information I was looking for... ;-)
>So an alternate approach is to set
> the minimum length as small as possible while ensuring that field is valid.
The fact is, I'm not sure how to do it for unsolicited messages.
Current code ensures/checks != COMPLETE_IO. Your comment above
and code audit suggest that we should add a check != FCHBA_DATA.
I saw ENUMERATE_BUS messages, code only using their "operation".
And, again, this is only based on current code/observations...
So, maybe you mean something like this (on top of this patch)?
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 349c1071a98d4..8fedac3c7597a 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -292,9 +292,6 @@ struct vmstorage_protocol_version {
#define STORAGE_CHANNEL_REMOVABLE_FLAG 0x1
#define STORAGE_CHANNEL_EMULATED_IDE_FLAG 0x2
-/* Lower bound on the size of unsolicited packets with ID of 0 */
-#define VSTOR_MIN_UNSOL_PKT_SIZE 48
-
struct vstor_packet {
/* Requested operation type */
enum vstor_packet_operation operation;
@@ -1291,7 +1288,7 @@ static void storvsc_on_channel_callback(void *context)
u32 pktlen = hv_pkt_datalen(desc);
u64 rqst_id = desc->trans_id;
u32 minlen = rqst_id ? sizeof(struct vstor_packet) -
- stor_device->vmscsi_size_delta : VSTOR_MIN_UNSOL_PKT_SIZE;
+ stor_device->vmscsi_size_delta : sizeof(enum vstor_packet_operation);
if (pktlen < minlen) {
dev_err(&device->device,
@@ -1315,7 +1312,8 @@ static void storvsc_on_channel_callback(void *context)
* storvsc_on_io_completion() with a guest memory address that is
* zero if Hyper-V were to construct and send such a bogus packet.
*/
- if (packet->operation == VSTOR_OPERATION_COMPLETE_IO) {
+ if (packet->operation == VSTOR_OPERATION_COMPLETE_IO ||
+ packet->operation == VSTOR_OPERATION_FCHBA_DATA) {
dev_err(&device->device, "Invalid packet with ID of 0\n");
continue;
}
Thanks,
Andrea
