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Message-Id: <20220328144244.100228-3-parri.andrea@gmail.com>
Date: Mon, 28 Mar 2022 16:42:42 +0200
From: "Andrea Parri (Microsoft)" <parri.andrea@...il.com>
To: KY Srinivasan <kys@...rosoft.com>,
Haiyang Zhang <haiyangz@...rosoft.com>,
Stephen Hemminger <sthemmin@...rosoft.com>,
Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
Michael Kelley <mikelley@...rosoft.com>,
Wei Hu <weh@...rosoft.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
Rob Herring <robh@...nel.org>,
Krzysztof Wilczynski <kw@...ux.com>,
Bjorn Helgaas <bhelgaas@...gle.com>
Cc: linux-hyperv@...r.kernel.org, linux-pci@...r.kernel.org,
linux-kernel@...r.kernel.org,
"Andrea Parri (Microsoft)" <parri.andrea@...il.com>
Subject: [RFC PATCH 2/4] PCI: hv: Use vmbus_requestor to generate transaction IDs for VMbus hardening
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@...rosoft.com>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@...il.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
+
/*
* 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)
--
2.25.1
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