| Message ID | 20220328144244.100228-3-parri.andrea@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Lorenzo Pieralisi |
| Headers | show |
| Series | PCI: hv: Miscellaneous changes | expand |
From: Andrea Parri (Microsoft) <parri.andrea@gmail.com> Sent: Monday, March 28, 2022 7:43 AM > > Currently, pointers to guest memory are passed to Hyper-V as transaction > IDs in hv_pci. In the face of errors or malicious behavior in Hyper-V, > hv_pci should not expose or trust the transaction IDs returned by > Hyper-V to be valid guest memory addresses. Instead, use small integers > generated by vmbus_requestor as request (transaction) IDs. > > Suggested-by: Michael Kelley <mikelley@microsoft.com> > Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com> > --- > drivers/pci/controller/pci-hyperv.c | 30 +++++++++++++++++++++-------- > 1 file changed, 22 insertions(+), 8 deletions(-) > > diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c > index ae0bc2fee4ca8..9f963a46b8298 100644 > --- a/drivers/pci/controller/pci-hyperv.c > +++ b/drivers/pci/controller/pci-hyperv.c > @@ -91,6 +91,9 @@ static enum pci_protocol_version_t pci_protocol_versions[] = { > /* space for 32bit serial number as string */ > #define SLOT_NAME_SIZE 11 > > +/* Size of requestor for VMbus */ > +#define HV_PCI_RQSTOR_SIZE 64 Might include a comment about how this value was derived. I *think* it is an arbitrary value based on the assumption that having more than one request outstanding is rare, and so 64 should be extremely generous in ensuring that we don't ever run out. > + > /* > * Message Types > */ > @@ -1407,7 +1410,7 @@ static void hv_int_desc_free(struct hv_pci_dev *hpdev, > int_pkt->wslot.slot = hpdev->desc.win_slot.slot; > int_pkt->int_desc = *int_desc; > vmbus_sendpacket(hpdev->hbus->hdev->channel, int_pkt, sizeof(*int_pkt), > - (unsigned long)&ctxt.pkt, VM_PKT_DATA_INBAND, 0); > + 0, VM_PKT_DATA_INBAND, 0); > kfree(int_desc); > } > > @@ -2649,7 +2652,7 @@ static void hv_eject_device_work(struct work_struct *work) > ejct_pkt->message_type.type = PCI_EJECTION_COMPLETE; > ejct_pkt->wslot.slot = hpdev->desc.win_slot.slot; > vmbus_sendpacket(hbus->hdev->channel, ejct_pkt, > - sizeof(*ejct_pkt), (unsigned long)&ctxt.pkt, > + sizeof(*ejct_pkt), 0, > VM_PKT_DATA_INBAND, 0); > > /* For the get_pcichild() in hv_pci_eject_device() */ > @@ -2696,8 +2699,9 @@ static void hv_pci_onchannelcallback(void *context) > const int packet_size = 0x100; > int ret; > struct hv_pcibus_device *hbus = context; > + struct vmbus_channel *chan = hbus->hdev->channel; Having gotten the channel as a local variable, could also use the local as the first argument to vmbus_recvpacket_raw(). > u32 bytes_recvd; > - u64 req_id; > + u64 req_id, req_addr; > struct vmpacket_descriptor *desc; > unsigned char *buffer; > int bufferlen = packet_size; > @@ -2743,11 +2747,13 @@ static void hv_pci_onchannelcallback(void *context) > switch (desc->type) { > case VM_PKT_COMP: > > - /* > - * The host is trusted, and thus it's safe to interpret > - * this transaction ID as a pointer. > - */ > - comp_packet = (struct pci_packet *)req_id; > + req_addr = chan->request_addr_callback(chan, req_id); > + if (req_addr == VMBUS_RQST_ERROR) { > + dev_warn_ratelimited(&hbus->hdev->device, > + "Invalid request ID\n"); Could you include the req_id value in the error message that is output? I was recently debugging a problem in the storvsc driver where having that value would have been handy. > + break; > + } > + comp_packet = (struct pci_packet *)req_addr; > response = (struct pci_response *)buffer; > comp_packet->completion_func(comp_packet->compl_ctxt, > response, > @@ -3419,6 +3425,10 @@ static int hv_pci_probe(struct hv_device *hdev, > goto free_dom; > } > > + hdev->channel->next_request_id_callback = vmbus_next_request_id; > + hdev->channel->request_addr_callback = vmbus_request_addr; > + hdev->channel->rqstor_size = HV_PCI_RQSTOR_SIZE; > + > ret = vmbus_open(hdev->channel, pci_ring_size, pci_ring_size, NULL, 0, > hv_pci_onchannelcallback, hbus); > if (ret) > @@ -3749,6 +3759,10 @@ static int hv_pci_resume(struct hv_device *hdev) > > hbus->state = hv_pcibus_init; > > + hdev->channel->next_request_id_callback = vmbus_next_request_id; > + hdev->channel->request_addr_callback = vmbus_request_addr; > + hdev->channel->rqstor_size = HV_PCI_RQSTOR_SIZE; > + > ret = vmbus_open(hdev->channel, pci_ring_size, pci_ring_size, NULL, 0, > hv_pci_onchannelcallback, hbus); > if (ret) > -- > 2.25.1
> > @@ -91,6 +91,9 @@ static enum pci_protocol_version_t pci_protocol_versions[] = { > > /* space for 32bit serial number as string */ > > #define SLOT_NAME_SIZE 11 > > > > +/* Size of requestor for VMbus */ > > +#define HV_PCI_RQSTOR_SIZE 64 > > Might include a comment about how this value was derived. I *think* > it is an arbitrary value based on the assumption that having more than > one request outstanding is rare, and so 64 should be extremely generous > in ensuring that we don't ever run out. Right, I've added a comment to that effect. > > @@ -2696,8 +2699,9 @@ static void hv_pci_onchannelcallback(void *context) > > const int packet_size = 0x100; > > int ret; > > struct hv_pcibus_device *hbus = context; > > + struct vmbus_channel *chan = hbus->hdev->channel; > > Having gotten the channel as a local variable, could also use the local as > the first argument to vmbus_recvpacket_raw(). Applied. > > @@ -2743,11 +2747,13 @@ static void hv_pci_onchannelcallback(void *context) > > switch (desc->type) { > > case VM_PKT_COMP: > > > > - /* > > - * The host is trusted, and thus it's safe to interpret > > - * this transaction ID as a pointer. > > - */ > > - comp_packet = (struct pci_packet *)req_id; > > + req_addr = chan->request_addr_callback(chan, req_id); > > + if (req_addr == VMBUS_RQST_ERROR) { > > + dev_warn_ratelimited(&hbus->hdev->device, > > + "Invalid request ID\n"); > > Could you include the req_id value in the error message that is output? I > was recently debugging a problem in the storvsc driver where having that > value would have been handy. Sure. Thanks, Andrea
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c index ae0bc2fee4ca8..9f963a46b8298 100644 --- a/drivers/pci/controller/pci-hyperv.c +++ b/drivers/pci/controller/pci-hyperv.c @@ -91,6 +91,9 @@ static enum pci_protocol_version_t pci_protocol_versions[] = { /* space for 32bit serial number as string */ #define SLOT_NAME_SIZE 11 +/* Size of requestor for VMbus */ +#define HV_PCI_RQSTOR_SIZE 64 + /* * Message Types */ @@ -1407,7 +1410,7 @@ static void hv_int_desc_free(struct hv_pci_dev *hpdev, int_pkt->wslot.slot = hpdev->desc.win_slot.slot; int_pkt->int_desc = *int_desc; vmbus_sendpacket(hpdev->hbus->hdev->channel, int_pkt, sizeof(*int_pkt), - (unsigned long)&ctxt.pkt, VM_PKT_DATA_INBAND, 0); + 0, VM_PKT_DATA_INBAND, 0); kfree(int_desc); } @@ -2649,7 +2652,7 @@ static void hv_eject_device_work(struct work_struct *work) ejct_pkt->message_type.type = PCI_EJECTION_COMPLETE; ejct_pkt->wslot.slot = hpdev->desc.win_slot.slot; vmbus_sendpacket(hbus->hdev->channel, ejct_pkt, - sizeof(*ejct_pkt), (unsigned long)&ctxt.pkt, + sizeof(*ejct_pkt), 0, VM_PKT_DATA_INBAND, 0); /* For the get_pcichild() in hv_pci_eject_device() */ @@ -2696,8 +2699,9 @@ static void hv_pci_onchannelcallback(void *context) const int packet_size = 0x100; int ret; struct hv_pcibus_device *hbus = context; + struct vmbus_channel *chan = hbus->hdev->channel; u32 bytes_recvd; - u64 req_id; + u64 req_id, req_addr; struct vmpacket_descriptor *desc; unsigned char *buffer; int bufferlen = packet_size; @@ -2743,11 +2747,13 @@ static void hv_pci_onchannelcallback(void *context) switch (desc->type) { case VM_PKT_COMP: - /* - * The host is trusted, and thus it's safe to interpret - * this transaction ID as a pointer. - */ - comp_packet = (struct pci_packet *)req_id; + req_addr = chan->request_addr_callback(chan, req_id); + if (req_addr == VMBUS_RQST_ERROR) { + dev_warn_ratelimited(&hbus->hdev->device, + "Invalid request ID\n"); + break; + } + comp_packet = (struct pci_packet *)req_addr; response = (struct pci_response *)buffer; comp_packet->completion_func(comp_packet->compl_ctxt, response, @@ -3419,6 +3425,10 @@ static int hv_pci_probe(struct hv_device *hdev, goto free_dom; } + hdev->channel->next_request_id_callback = vmbus_next_request_id; + hdev->channel->request_addr_callback = vmbus_request_addr; + hdev->channel->rqstor_size = HV_PCI_RQSTOR_SIZE; + ret = vmbus_open(hdev->channel, pci_ring_size, pci_ring_size, NULL, 0, hv_pci_onchannelcallback, hbus); if (ret) @@ -3749,6 +3759,10 @@ static int hv_pci_resume(struct hv_device *hdev) hbus->state = hv_pcibus_init; + hdev->channel->next_request_id_callback = vmbus_next_request_id; + hdev->channel->request_addr_callback = vmbus_request_addr; + hdev->channel->rqstor_size = HV_PCI_RQSTOR_SIZE; + ret = vmbus_open(hdev->channel, pci_ring_size, pci_ring_size, NULL, 0, hv_pci_onchannelcallback, hbus); if (ret)
Currently, pointers to guest memory are passed to Hyper-V as transaction IDs in hv_pci. In the face of errors or malicious behavior in Hyper-V, hv_pci should not expose or trust the transaction IDs returned by Hyper-V to be valid guest memory addresses. Instead, use small integers generated by vmbus_requestor as request (transaction) IDs. Suggested-by: Michael Kelley <mikelley@microsoft.com> Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com> --- drivers/pci/controller/pci-hyperv.c | 30 +++++++++++++++++++++-------- 1 file changed, 22 insertions(+), 8 deletions(-)