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Subject[PATCH 1/2] PCI: hv: Use IDR to generate transaction IDs for VMBus hardening
Date
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 IDR 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 | 190 ++++++++++++++++++++--------
1 file changed, 135 insertions(+), 55 deletions(-)

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index ae0bc2fee4ca8..fbc62aab08fdc 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -495,6 +495,9 @@ struct hv_pcibus_device {
spinlock_t device_list_lock; /* Protect lists below */
void __iomem *cfg_addr;

+ spinlock_t idr_lock; /* Serialize accesses to the IDR */
+ struct idr idr; /* Map guest memory addresses */
+
struct list_head children;
struct list_head dr_list;

@@ -1208,6 +1211,27 @@ static void hv_pci_read_config_compl(void *context, struct pci_response *resp,
complete(&comp->comp_pkt.host_event);
}

+static inline int alloc_request_id(struct hv_pcibus_device *hbus,
+ void *ptr, gfp_t gfp)
+{
+ unsigned long flags;
+ int req_id;
+
+ spin_lock_irqsave(&hbus->idr_lock, flags);
+ req_id = idr_alloc(&hbus->idr, ptr, 1, 0, gfp);
+ spin_unlock_irqrestore(&hbus->idr_lock, flags);
+ return req_id;
+}
+
+static inline void remove_request_id(struct hv_pcibus_device *hbus, int req_id)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&hbus->idr_lock, flags);
+ idr_remove(&hbus->idr, req_id);
+ spin_unlock_irqrestore(&hbus->idr_lock, flags);
+}
+
/**
* hv_read_config_block() - Sends a read config block request to
* the back-end driver running in the Hyper-V parent partition.
@@ -1232,7 +1256,7 @@ static int hv_read_config_block(struct pci_dev *pdev, void *buf,
} pkt;
struct hv_read_config_compl comp_pkt;
struct pci_read_block *read_blk;
- int ret;
+ int req_id, ret;

if (len == 0 || len > HV_CONFIG_BLOCK_SIZE_MAX)
return -EINVAL;
@@ -1250,16 +1274,19 @@ static int hv_read_config_block(struct pci_dev *pdev, void *buf,
read_blk->block_id = block_id;
read_blk->bytes_requested = len;

+ req_id = alloc_request_id(hbus, &pkt.pkt, GFP_KERNEL);
+ if (req_id < 0)
+ return req_id;
+
ret = vmbus_sendpacket(hbus->hdev->channel, read_blk,
- sizeof(*read_blk), (unsigned long)&pkt.pkt,
- VM_PKT_DATA_INBAND,
+ sizeof(*read_blk), req_id, VM_PKT_DATA_INBAND,
VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
if (ret)
- return ret;
+ goto exit;

ret = wait_for_response(hbus->hdev, &comp_pkt.comp_pkt.host_event);
if (ret)
- return ret;
+ goto exit;

if (comp_pkt.comp_pkt.completion_status != 0 ||
comp_pkt.bytes_returned == 0) {
@@ -1267,11 +1294,14 @@ static int hv_read_config_block(struct pci_dev *pdev, void *buf,
"Read Config Block failed: 0x%x, bytes_returned=%d\n",
comp_pkt.comp_pkt.completion_status,
comp_pkt.bytes_returned);
- return -EIO;
+ ret = -EIO;
+ goto exit;
}

*bytes_returned = comp_pkt.bytes_returned;
- return 0;
+exit:
+ remove_request_id(hbus, req_id);
+ return ret;
}

/**
@@ -1313,8 +1343,8 @@ static int hv_write_config_block(struct pci_dev *pdev, void *buf,
} pkt;
struct hv_pci_compl comp_pkt;
struct pci_write_block *write_blk;
+ int req_id, ret;
u32 pkt_size;
- int ret;

if (len == 0 || len > HV_CONFIG_BLOCK_SIZE_MAX)
return -EINVAL;
@@ -1340,24 +1370,30 @@ static int hv_write_config_block(struct pci_dev *pdev, void *buf,
*/
pkt_size += sizeof(pkt.reserved);

+ req_id = alloc_request_id(hbus, &pkt.pkt, GFP_KERNEL);
+ if (req_id < 0)
+ return req_id;
+
ret = vmbus_sendpacket(hbus->hdev->channel, write_blk, pkt_size,
- (unsigned long)&pkt.pkt, VM_PKT_DATA_INBAND,
+ req_id, VM_PKT_DATA_INBAND,
VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
if (ret)
- return ret;
+ goto exit;

ret = wait_for_response(hbus->hdev, &comp_pkt.host_event);
if (ret)
- return ret;
+ goto exit;

if (comp_pkt.completion_status != 0) {
dev_err(&hbus->hdev->device,
"Write Config Block failed: 0x%x\n",
comp_pkt.completion_status);
- return -EIO;
+ ret = -EIO;
}

- return 0;
+exit:
+ remove_request_id(hbus, req_id);
+ return ret;
}

/**
@@ -1407,7 +1443,7 @@ 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);
}

@@ -1688,9 +1724,8 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
struct pci_create_interrupt3 v3;
} int_pkts;
} __packed ctxt;
-
+ int req_id, ret;
u32 size;
- int ret;

pdev = msi_desc_to_pci_dev(irq_data_get_msi_desc(data));
dest = irq_data_get_effective_affinity_mask(data);
@@ -1750,15 +1785,18 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
goto free_int_desc;
}

+ req_id = alloc_request_id(hbus, &ctxt.pci_pkt, GFP_ATOMIC);
+ if (req_id < 0)
+ goto free_int_desc;
+
ret = vmbus_sendpacket(hpdev->hbus->hdev->channel, &ctxt.int_pkts,
- size, (unsigned long)&ctxt.pci_pkt,
- VM_PKT_DATA_INBAND,
+ size, req_id, VM_PKT_DATA_INBAND,
VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
if (ret) {
dev_err(&hbus->hdev->device,
"Sending request for interrupt failed: 0x%x",
comp.comp_pkt.completion_status);
- goto free_int_desc;
+ goto remove_id;
}

/*
@@ -1811,7 +1849,7 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
dev_err(&hbus->hdev->device,
"Request for interrupt failed: 0x%x",
comp.comp_pkt.completion_status);
- goto free_int_desc;
+ goto remove_id;
}

/*
@@ -1827,11 +1865,14 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
msg->address_lo = comp.int_desc.address & 0xffffffff;
msg->data = comp.int_desc.data;

+ remove_request_id(hbus, req_id);
put_pcichild(hpdev);
return;

enable_tasklet:
tasklet_enable(&channel->callback_event);
+remove_id:
+ remove_request_id(hbus, req_id);
free_int_desc:
kfree(int_desc);
drop_reference:
@@ -2258,7 +2299,7 @@ static struct hv_pci_dev *new_pcichild_device(struct hv_pcibus_device *hbus,
u8 buffer[sizeof(struct pci_child_message)];
} pkt;
unsigned long flags;
- int ret;
+ int req_id, ret;

hpdev = kzalloc(sizeof(*hpdev), GFP_KERNEL);
if (!hpdev)
@@ -2275,16 +2316,19 @@ static struct hv_pci_dev *new_pcichild_device(struct hv_pcibus_device *hbus,
res_req->message_type.type = PCI_QUERY_RESOURCE_REQUIREMENTS;
res_req->wslot.slot = desc->win_slot.slot;

+ req_id = alloc_request_id(hbus, &pkt.init_packet, GFP_KERNEL);
+ if (req_id < 0)
+ goto error;
+
ret = vmbus_sendpacket(hbus->hdev->channel, res_req,
- sizeof(struct pci_child_message),
- (unsigned long)&pkt.init_packet,
+ sizeof(struct pci_child_message), req_id,
VM_PKT_DATA_INBAND,
VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
if (ret)
- goto error;
+ goto remove_id;

if (wait_for_response(hbus->hdev, &comp_pkt.host_event))
- goto error;
+ goto remove_id;

hpdev->desc = *desc;
refcount_set(&hpdev->refs, 1);
@@ -2293,8 +2337,11 @@ static struct hv_pci_dev *new_pcichild_device(struct hv_pcibus_device *hbus,

list_add_tail(&hpdev->list_entry, &hbus->children);
spin_unlock_irqrestore(&hbus->device_list_lock, flags);
+ remove_request_id(hbus, req_id);
return hpdev;

+remove_id:
+ remove_request_id(hbus, req_id);
error:
kfree(hpdev);
return NULL;
@@ -2648,8 +2695,7 @@ static void hv_eject_device_work(struct work_struct *work)
ejct_pkt = (struct pci_eject_response *)&ctxt.pkt.message;
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,
+ vmbus_sendpacket(hbus->hdev->channel, ejct_pkt, sizeof(*ejct_pkt), 0,
VM_PKT_DATA_INBAND, 0);

/* For the get_pcichild() in hv_pci_eject_device() */
@@ -2709,6 +2755,7 @@ static void hv_pci_onchannelcallback(void *context)
struct pci_dev_inval_block *inval;
struct pci_dev_incoming *dev_message;
struct hv_pci_dev *hpdev;
+ unsigned long flags;

buffer = kmalloc(bufferlen, GFP_ATOMIC);
if (!buffer)
@@ -2743,11 +2790,19 @@ 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;
+ if (req_id > INT_MAX) {
+ dev_err_ratelimited(&hbus->hdev->device,
+ "Request ID > INT_MAX\n");
+ break;
+ }
+ spin_lock_irqsave(&hbus->idr_lock, flags);
+ comp_packet = (struct pci_packet *)idr_find(&hbus->idr, req_id);
+ spin_unlock_irqrestore(&hbus->idr_lock, flags);
+ if (!comp_packet) {
+ dev_warn_ratelimited(&hbus->hdev->device,
+ "Request ID not found\n");
+ break;
+ }
response = (struct pci_response *)buffer;
comp_packet->completion_func(comp_packet->compl_ctxt,
response,
@@ -2858,8 +2913,7 @@ static int hv_pci_protocol_negotiation(struct hv_device *hdev,
struct pci_version_request *version_req;
struct hv_pci_compl comp_pkt;
struct pci_packet *pkt;
- int ret;
- int i;
+ int req_id, ret, i;

/*
* Initiate the handshake with the host and negotiate
@@ -2877,12 +2931,18 @@ static int hv_pci_protocol_negotiation(struct hv_device *hdev,
version_req = (struct pci_version_request *)&pkt->message;
version_req->message_type.type = PCI_QUERY_PROTOCOL_VERSION;

+ req_id = alloc_request_id(hbus, pkt, GFP_KERNEL);
+ if (req_id < 0) {
+ kfree(pkt);
+ return req_id;
+ }
+
for (i = 0; i < num_version; i++) {
version_req->protocol_version = version[i];
ret = vmbus_sendpacket(hdev->channel, version_req,
- sizeof(struct pci_version_request),
- (unsigned long)pkt, VM_PKT_DATA_INBAND,
- VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+ sizeof(struct pci_version_request),
+ req_id, VM_PKT_DATA_INBAND,
+ VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
if (!ret)
ret = wait_for_response(hdev, &comp_pkt.host_event);

@@ -2917,6 +2977,7 @@ static int hv_pci_protocol_negotiation(struct hv_device *hdev,
ret = -EPROTO;

exit:
+ remove_request_id(hbus, req_id);
kfree(pkt);
return ret;
}
@@ -3079,7 +3140,7 @@ static int hv_pci_enter_d0(struct hv_device *hdev)
struct pci_bus_d0_entry *d0_entry;
struct hv_pci_compl comp_pkt;
struct pci_packet *pkt;
- int ret;
+ int req_id, ret;

/*
* Tell the host that the bus is ready to use, and moved into the
@@ -3098,8 +3159,14 @@ static int hv_pci_enter_d0(struct hv_device *hdev)
d0_entry->message_type.type = PCI_BUS_D0ENTRY;
d0_entry->mmio_base = hbus->mem_config->start;

+ req_id = alloc_request_id(hbus, pkt, GFP_KERNEL);
+ if (req_id < 0) {
+ kfree(pkt);
+ return req_id;
+ }
+
ret = vmbus_sendpacket(hdev->channel, d0_entry, sizeof(*d0_entry),
- (unsigned long)pkt, VM_PKT_DATA_INBAND,
+ req_id, VM_PKT_DATA_INBAND,
VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
if (!ret)
ret = wait_for_response(hdev, &comp_pkt.host_event);
@@ -3112,12 +3179,10 @@ static int hv_pci_enter_d0(struct hv_device *hdev)
"PCI Pass-through VSP failed D0 Entry with status %x\n",
comp_pkt.completion_status);
ret = -EPROTO;
- goto exit;
}

- ret = 0;
-
exit:
+ remove_request_id(hbus, req_id);
kfree(pkt);
return ret;
}
@@ -3175,11 +3240,10 @@ static int hv_send_resources_allocated(struct hv_device *hdev)
struct pci_resources_assigned *res_assigned;
struct pci_resources_assigned2 *res_assigned2;
struct hv_pci_compl comp_pkt;
+ int wslot, req_id, ret = 0;
struct hv_pci_dev *hpdev;
struct pci_packet *pkt;
size_t size_res;
- int wslot;
- int ret;

size_res = (hbus->protocol_version < PCI_PROTOCOL_VERSION_1_2)
? sizeof(*res_assigned) : sizeof(*res_assigned2);
@@ -3188,7 +3252,11 @@ static int hv_send_resources_allocated(struct hv_device *hdev)
if (!pkt)
return -ENOMEM;

- ret = 0;
+ req_id = alloc_request_id(hbus, pkt, GFP_KERNEL);
+ if (req_id < 0) {
+ kfree(pkt);
+ return req_id;
+ }

for (wslot = 0; wslot < 256; wslot++) {
hpdev = get_pcichild_wslot(hbus, wslot);
@@ -3215,10 +3283,9 @@ static int hv_send_resources_allocated(struct hv_device *hdev)
}
put_pcichild(hpdev);

- ret = vmbus_sendpacket(hdev->channel, &pkt->message,
- size_res, (unsigned long)pkt,
- VM_PKT_DATA_INBAND,
- VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+ ret = vmbus_sendpacket(hdev->channel, &pkt->message, size_res,
+ req_id, VM_PKT_DATA_INBAND,
+ VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
if (!ret)
ret = wait_for_response(hdev, &comp_pkt.host_event);
if (ret)
@@ -3235,6 +3302,7 @@ static int hv_send_resources_allocated(struct hv_device *hdev)
hbus->wslot_res_allocated = wslot;
}

+ remove_request_id(hbus, req_id);
kfree(pkt);
return ret;
}
@@ -3412,6 +3480,7 @@ static int hv_pci_probe(struct hv_device *hdev,
spin_lock_init(&hbus->config_lock);
spin_lock_init(&hbus->device_list_lock);
spin_lock_init(&hbus->retarget_msi_interrupt_lock);
+ spin_lock_init(&hbus->idr_lock);
hbus->wq = alloc_ordered_workqueue("hv_pci_%x", 0,
hbus->bridge->domain_nr);
if (!hbus->wq) {
@@ -3419,6 +3488,7 @@ static int hv_pci_probe(struct hv_device *hdev,
goto free_dom;
}

+ idr_init(&hbus->idr);
ret = vmbus_open(hdev->channel, pci_ring_size, pci_ring_size, NULL, 0,
hv_pci_onchannelcallback, hbus);
if (ret)
@@ -3537,6 +3607,7 @@ static int hv_pci_probe(struct hv_device *hdev,
hv_free_config_window(hbus);
close:
vmbus_close(hdev->channel);
+ idr_destroy(&hbus->idr);
destroy_wq:
destroy_workqueue(hbus->wq);
free_dom:
@@ -3556,7 +3627,7 @@ static int hv_pci_bus_exit(struct hv_device *hdev, bool keep_devs)
struct hv_pci_compl comp_pkt;
struct hv_pci_dev *hpdev, *tmp;
unsigned long flags;
- int ret;
+ int req_id, ret;

/*
* After the host sends the RESCIND_CHANNEL message, it doesn't
@@ -3599,18 +3670,23 @@ static int hv_pci_bus_exit(struct hv_device *hdev, bool keep_devs)
pkt.teardown_packet.compl_ctxt = &comp_pkt;
pkt.teardown_packet.message[0].type = PCI_BUS_D0EXIT;

+ req_id = alloc_request_id(hbus, &pkt.teardown_packet, GFP_KERNEL);
+ if (req_id < 0)
+ return req_id;
+
ret = vmbus_sendpacket(hdev->channel, &pkt.teardown_packet.message,
- sizeof(struct pci_message),
- (unsigned long)&pkt.teardown_packet,
+ sizeof(struct pci_message), req_id,
VM_PKT_DATA_INBAND,
VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
if (ret)
- return ret;
+ goto exit;

if (wait_for_completion_timeout(&comp_pkt.host_event, 10 * HZ) == 0)
- return -ETIMEDOUT;
+ ret = -ETIMEDOUT;

- return 0;
+exit:
+ remove_request_id(hbus, req_id);
+ return ret;
}

/**
@@ -3648,6 +3724,7 @@ static int hv_pci_remove(struct hv_device *hdev)
ret = hv_pci_bus_exit(hdev, false);

vmbus_close(hdev->channel);
+ idr_destroy(&hbus->idr);

iounmap(hbus->cfg_addr);
hv_free_config_window(hbus);
@@ -3704,6 +3781,7 @@ static int hv_pci_suspend(struct hv_device *hdev)
return ret;

vmbus_close(hdev->channel);
+ idr_destroy(&hbus->idr);

return 0;
}
@@ -3749,6 +3827,7 @@ static int hv_pci_resume(struct hv_device *hdev)

hbus->state = hv_pcibus_init;

+ idr_init(&hbus->idr);
ret = vmbus_open(hdev->channel, pci_ring_size, pci_ring_size, NULL, 0,
hv_pci_onchannelcallback, hbus);
if (ret)
@@ -3780,6 +3859,7 @@ static int hv_pci_resume(struct hv_device *hdev)
return 0;
out:
vmbus_close(hdev->channel);
+ idr_destroy(&hbus->idr);
return ret;
}

--
2.25.1
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