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Subject[PATCH v2 3/3] hv_netvsc: Use vmbus_requestor to generate transaction IDs for VMBus hardening
Date
Currently, pointers to guest memory are passed to Hyper-V as
transaction IDs in netvsc. In the face of errors or malicious
behavior in Hyper-V, netvsc 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 requests
(transaction) IDs.

Cc: David S. Miller <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org
Signed-off-by: Andres Beltran <lkmlabelt@gmail.com>
---
Changes in v2:
- Add casts to unsigned long to fix warnings on 32bit.
- Use an inline function to get the requestor size.

drivers/net/hyperv/hyperv_net.h | 13 +++++
drivers/net/hyperv/netvsc.c | 79 +++++++++++++++++++++++++------
drivers/net/hyperv/rndis_filter.c | 1 +
include/linux/hyperv.h | 1 +
4 files changed, 80 insertions(+), 14 deletions(-)

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index abda736e7c7d..f43b614f2345 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -847,6 +847,19 @@ struct nvsp_message {

#define NETVSC_XDP_HDRM 256

+#define NETVSC_MIN_OUT_MSG_SIZE (sizeof(struct vmpacket_descriptor) + \
+ sizeof(struct nvsp_message))
+#define NETVSC_MIN_IN_MSG_SIZE sizeof(struct vmpacket_descriptor)
+
+/* Estimated requestor size:
+ * out_ring_size/min_out_msg_size + in_ring_size/min_in_msg_size
+ */
+static inline u32 netvsc_rqstor_size(unsigned long ringbytes)
+{
+ return ringbytes / NETVSC_MIN_OUT_MSG_SIZE +
+ ringbytes / NETVSC_MIN_IN_MSG_SIZE;
+}
+
struct multi_send_data {
struct sk_buff *skb; /* skb containing the pkt */
struct hv_netvsc_packet *pkt; /* netvsc pkt pending */
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 41f5cf0bb997..79b907a29433 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -50,7 +50,7 @@ void netvsc_switch_datapath(struct net_device *ndev, bool vf)

vmbus_sendpacket(dev->channel, init_pkt,
sizeof(struct nvsp_message),
- (unsigned long)init_pkt,
+ VMBUS_RQST_ID_NO_RESPONSE,
VM_PKT_DATA_INBAND, 0);
}

@@ -163,7 +163,7 @@ static void netvsc_revoke_recv_buf(struct hv_device *device,
ret = vmbus_sendpacket(device->channel,
revoke_packet,
sizeof(struct nvsp_message),
- (unsigned long)revoke_packet,
+ VMBUS_RQST_ID_NO_RESPONSE,
VM_PKT_DATA_INBAND, 0);
/* If the failure is because the channel is rescinded;
* ignore the failure since we cannot send on a rescinded
@@ -213,7 +213,7 @@ static void netvsc_revoke_send_buf(struct hv_device *device,
ret = vmbus_sendpacket(device->channel,
revoke_packet,
sizeof(struct nvsp_message),
- (unsigned long)revoke_packet,
+ VMBUS_RQST_ID_NO_RESPONSE,
VM_PKT_DATA_INBAND, 0);

/* If the failure is because the channel is rescinded;
@@ -304,6 +304,7 @@ static int netvsc_init_buf(struct hv_device *device,
unsigned int buf_size;
size_t map_words;
int ret = 0;
+ u64 rqst_id;

/* Get receive buffer area. */
buf_size = device_info->recv_sections * device_info->recv_section_size;
@@ -350,13 +351,22 @@ static int netvsc_init_buf(struct hv_device *device,

trace_nvsp_send(ndev, init_packet);

+ rqst_id = vmbus_next_request_id(&device->channel->requestor,
+ (unsigned long)init_packet);
+ if (rqst_id == VMBUS_RQST_ERROR) {
+ netdev_err(ndev, "No request id available\n");
+ goto cleanup;
+ }
+
/* Send the gpadl notification request */
ret = vmbus_sendpacket(device->channel, init_packet,
sizeof(struct nvsp_message),
- (unsigned long)init_packet,
+ rqst_id,
VM_PKT_DATA_INBAND,
VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
if (ret != 0) {
+ /* Reclaim request ID to avoid leak of IDs */
+ vmbus_request_addr(&device->channel->requestor, rqst_id);
netdev_err(ndev,
"unable to send receive buffer's gpadl to netvsp\n");
goto cleanup;
@@ -432,13 +442,22 @@ static int netvsc_init_buf(struct hv_device *device,

trace_nvsp_send(ndev, init_packet);

+ rqst_id = vmbus_next_request_id(&device->channel->requestor,
+ (unsigned long)init_packet);
+ if (rqst_id == VMBUS_RQST_ERROR) {
+ netdev_err(ndev, "No request id available\n");
+ goto cleanup;
+ }
+
/* Send the gpadl notification request */
ret = vmbus_sendpacket(device->channel, init_packet,
sizeof(struct nvsp_message),
- (unsigned long)init_packet,
+ rqst_id,
VM_PKT_DATA_INBAND,
VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
if (ret != 0) {
+ /* Reclaim request ID to avoid leak of IDs */
+ vmbus_request_addr(&device->channel->requestor, rqst_id);
netdev_err(ndev,
"unable to send send buffer's gpadl to netvsp\n");
goto cleanup;
@@ -496,6 +515,7 @@ static int negotiate_nvsp_ver(struct hv_device *device,
{
struct net_device *ndev = hv_get_drvdata(device);
int ret;
+ u64 rqst_id;

memset(init_packet, 0, sizeof(struct nvsp_message));
init_packet->hdr.msg_type = NVSP_MSG_TYPE_INIT;
@@ -503,15 +523,25 @@ static int negotiate_nvsp_ver(struct hv_device *device,
init_packet->msg.init_msg.init.max_protocol_ver = nvsp_ver;
trace_nvsp_send(ndev, init_packet);

+ rqst_id = vmbus_next_request_id(&device->channel->requestor,
+ (unsigned long)init_packet);
+ if (rqst_id == VMBUS_RQST_ERROR) {
+ netdev_err(ndev, "No request id available\n");
+ return -EAGAIN;
+ }
+
/* Send the init request */
ret = vmbus_sendpacket(device->channel, init_packet,
sizeof(struct nvsp_message),
- (unsigned long)init_packet,
+ rqst_id,
VM_PKT_DATA_INBAND,
VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);

- if (ret != 0)
+ if (ret != 0) {
+ /* Reclaim request ID to avoid leak of IDs */
+ vmbus_request_addr(&device->channel->requestor, rqst_id);
return ret;
+ }

wait_for_completion(&net_device->channel_init_wait);

@@ -542,7 +572,7 @@ static int negotiate_nvsp_ver(struct hv_device *device,

ret = vmbus_sendpacket(device->channel, init_packet,
sizeof(struct nvsp_message),
- (unsigned long)init_packet,
+ VMBUS_RQST_ID_NO_RESPONSE,
VM_PKT_DATA_INBAND, 0);

return ret;
@@ -599,7 +629,7 @@ static int netvsc_connect_vsp(struct hv_device *device,
/* Send the init request */
ret = vmbus_sendpacket(device->channel, init_packet,
sizeof(struct nvsp_message),
- (unsigned long)init_packet,
+ VMBUS_RQST_ID_NO_RESPONSE,
VM_PKT_DATA_INBAND, 0);
if (ret != 0)
goto cleanup;
@@ -680,10 +710,19 @@ static void netvsc_send_tx_complete(struct net_device *ndev,
const struct vmpacket_descriptor *desc,
int budget)
{
- struct sk_buff *skb = (struct sk_buff *)(unsigned long)desc->trans_id;
+ struct sk_buff *skb;
struct net_device_context *ndev_ctx = netdev_priv(ndev);
u16 q_idx = 0;
int queue_sends;
+ u64 cmd_rqst;
+
+ cmd_rqst = vmbus_request_addr(&channel->requestor, (u64)desc->trans_id);
+ if (cmd_rqst == VMBUS_RQST_ERROR) {
+ netdev_err(ndev, "Incorrect transaction id\n");
+ return;
+ }
+
+ skb = (struct sk_buff *)(unsigned long)cmd_rqst;

/* Notify the layer above us */
if (likely(skb)) {
@@ -822,7 +861,7 @@ static inline int netvsc_send_pkt(
struct net_device *ndev = hv_get_drvdata(device);
struct net_device_context *ndev_ctx = netdev_priv(ndev);
struct netdev_queue *txq = netdev_get_tx_queue(ndev, packet->q_idx);
- u64 req_id;
+ u64 rqst_id;
int ret;
u32 ring_avail = hv_get_avail_to_write_percent(&out_channel->outbound);

@@ -838,13 +877,19 @@ static inline int netvsc_send_pkt(
else
rpkt->send_buf_section_size = packet->total_data_buflen;

- req_id = (ulong)skb;

if (out_channel->rescind)
return -ENODEV;

trace_nvsp_send_pkt(ndev, out_channel, rpkt);

+ rqst_id = vmbus_next_request_id(&out_channel->requestor,
+ (unsigned long)skb);
+ if (rqst_id == VMBUS_RQST_ERROR) {
+ ret = -EAGAIN;
+ goto ret_check;
+ }
+
if (packet->page_buf_cnt) {
if (packet->cp_partial)
pb += packet->rmsg_pgcnt;
@@ -852,14 +897,15 @@ static inline int netvsc_send_pkt(
ret = vmbus_sendpacket_pagebuffer(out_channel,
pb, packet->page_buf_cnt,
&nvmsg, sizeof(nvmsg),
- req_id);
+ rqst_id);
} else {
ret = vmbus_sendpacket(out_channel,
&nvmsg, sizeof(nvmsg),
- req_id, VM_PKT_DATA_INBAND,
+ rqst_id, VM_PKT_DATA_INBAND,
VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
}

+ret_check:
if (ret == 0) {
atomic_inc_return(&nvchan->queue_sends);

@@ -868,9 +914,13 @@ static inline int netvsc_send_pkt(
ndev_ctx->eth_stats.stop_queue++;
}
} else if (ret == -EAGAIN) {
+ /* Reclaim request ID to avoid leak of IDs */
+ vmbus_request_addr(&out_channel->requestor, rqst_id);
netif_tx_stop_queue(txq);
ndev_ctx->eth_stats.stop_queue++;
} else {
+ /* Reclaim request ID to avoid leak of IDs */
+ vmbus_request_addr(&out_channel->requestor, rqst_id);
netdev_err(ndev,
"Unable to send packet pages %u len %u, ret %d\n",
packet->page_buf_cnt, packet->total_data_buflen,
@@ -1422,6 +1472,7 @@ struct netvsc_device *netvsc_device_add(struct hv_device *device,
netvsc_poll, NAPI_POLL_WEIGHT);

/* Open the channel */
+ device->channel->rqstor_size = netvsc_rqstor_size(netvsc_ring_bytes);
ret = vmbus_open(device->channel, netvsc_ring_bytes,
netvsc_ring_bytes, NULL, 0,
netvsc_channel_cb, net_device->chan_table);
diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index b81ceba38218..10489ba44a09 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -1114,6 +1114,7 @@ static void netvsc_sc_open(struct vmbus_channel *new_sc)
/* Set the channel before opening.*/
nvchan->channel = new_sc;

+ new_sc->rqstor_size = netvsc_rqstor_size(netvsc_ring_bytes);
ret = vmbus_open(new_sc, netvsc_ring_bytes,
netvsc_ring_bytes, NULL, 0,
netvsc_channel_cb, nvchan);
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index c509d20ab7db..d8194924983d 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -730,6 +730,7 @@ struct vmbus_requestor {
};

#define VMBUS_RQST_ERROR U64_MAX
+#define VMBUS_RQST_ID_NO_RESPONSE (U64_MAX - 1)

struct vmbus_device {
u16 dev_type;
--
2.25.1
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