Pointers to ring-buffer packets sent by Hyper-V are used within the
guest VM. Hyper-V can send packets with erroneous values or modify
packet fields after they are processed by the guest. To defend
against these scenarios, return a copy of the incoming VMBus packet
after validating its length and offset fields in hv_pkt_iter_first().
In this way, the packet can no longer be modified by the host.
Cc: James E.J. Bottomley <jejb@xxxxxxxxxxxxx>
Cc: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: linux-scsi@xxxxxxxxxxxxxxx
Cc: netdev@xxxxxxxxxxxxxxx
Signed-off-by: Andres Beltran <lkmlabelt@xxxxxxxxx>
---
Changes in v2:
- Removed unused variable in storvsc_connect_to_vsp().
drivers/hv/channel.c | 9 +++--
drivers/hv/hyperv_vmbus.h | 2 +-
drivers/hv/ring_buffer.c | 61 ++++++++++++++++++++++++++++---
drivers/net/hyperv/hyperv_net.h | 7 ++++
drivers/net/hyperv/netvsc.c | 2 +
drivers/net/hyperv/rndis_filter.c | 2 +
drivers/scsi/storvsc_drv.c | 10 +++++
include/linux/hyperv.h | 9 +++++
8 files changed, 93 insertions(+), 9 deletions(-)
diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index c16ddd3e5ce1..369628fe811d 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -206,12 +206,15 @@ static int __vmbus_open(struct vmbus_channel *newchannel,
newchannel->onchannel_callback = onchannelcallback;
newchannel->channel_callback_context = context;
- err = hv_ringbuffer_init(&newchannel->outbound, page, send_pages);
+ if (!newchannel->max_pkt_size)
+ newchannel->max_pkt_size = VMBUS_DEFAULT_MAX_PKT_SIZE;
+
+ err = hv_ringbuffer_init(&newchannel->outbound, page, send_pages, 0);
if (err)
goto error_clean_ring;
- err = hv_ringbuffer_init(&newchannel->inbound,
- &page[send_pages], recv_pages);
+ err = hv_ringbuffer_init(&newchannel->inbound, &page[send_pages],
+ recv_pages, newchannel->max_pkt_size);
if (err)
goto error_clean_ring;
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 40e2b9f91163..ff755e5d65fd 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -174,7 +174,7 @@ extern int hv_synic_cleanup(unsigned int cpu);
void hv_ringbuffer_pre_init(struct vmbus_channel *channel);
int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
- struct page *pages, u32 pagecnt);
+ struct page *pages, u32 pagecnt, u32 max_pkt_size);
void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info);
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 356e22159e83..172d78256445 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -190,7 +190,7 @@ void hv_ringbuffer_pre_init(struct vmbus_channel *channel)
/* Initialize the ring buffer. */
int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
- struct page *pages, u32 page_cnt)
+ struct page *pages, u32 page_cnt, u32 max_pkt_size)
{
int i;
struct page **pages_wraparound;
@@ -232,6 +232,14 @@ int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
sizeof(struct hv_ring_buffer);
ring_info->priv_read_index = 0;
+ /* Initialize buffer that holds copies of incoming packets */
+ if (max_pkt_size) {
+ ring_info->pkt_buffer = kmalloc(max_pkt_size, GFP_KERNEL);
+ if (!ring_info->pkt_buffer)
+ return -ENOMEM;
+ ring_info->pkt_buffer_size = max_pkt_size;
+ }
+
spin_lock_init(&ring_info->ring_lock);
return 0;
@@ -244,6 +252,9 @@ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
vunmap(ring_info->ring_buffer);
ring_info->ring_buffer = NULL;
mutex_unlock(&ring_info->ring_buffer_mutex);
+
+ kfree(ring_info->pkt_buffer);
+ ring_info->pkt_buffer_size = 0;
}
/* Write to the ring buffer. */
@@ -395,16 +406,56 @@ struct vmpacket_descriptor *hv_pkt_iter_first(struct vmbus_channel *channel)
{
struct hv_ring_buffer_info *rbi = &channel->inbound;
struct vmpacket_descriptor *desc;
+ struct vmpacket_descriptor *desc_copy;
+ u32 bytes_avail, pkt_len, pkt_offset;
hv_debug_delay_test(channel, MESSAGE_DELAY);
- if (hv_pkt_iter_avail(rbi) < sizeof(struct vmpacket_descriptor))
+
+ bytes_avail = hv_pkt_iter_avail(rbi);
+ if (bytes_avail < sizeof(struct vmpacket_descriptor))
return NULL;
desc = hv_get_ring_buffer(rbi) + rbi->priv_read_index;
- if (desc)
- prefetch((char *)desc + (desc->len8 << 3));
+ if (!desc)
+ return desc;
+
+ /*
+ * Ensure the compiler does not use references to incoming Hyper-V values (which
+ * could change at any moment) when reading local variables later in the code
+ */
+ pkt_len = READ_ONCE(desc->len8) << 3;
+ pkt_offset = READ_ONCE(desc->offset8) << 3;
+
+ /*
+ * If pkt_len is invalid, set it to the smaller of hv_pkt_iter_avail() and
+ * rbi->pkt_buffer_size
+ */
+ if (rbi->pkt_buffer_size < bytes_avail)
+ bytes_avail = rbi->pkt_buffer_size;
+
+ if (pkt_len <= sizeof(struct vmpacket_descriptor) || pkt_len > bytes_avail)
+ pkt_len = bytes_avail;
+
+ /*
+ * If pkt_offset it is invalid, arbitrarily set it to
+ * the size of vmpacket_descriptor
+ */
+ if (pkt_offset < sizeof(struct vmpacket_descriptor) || pkt_offset >= pkt_len)
+ pkt_offset = sizeof(struct vmpacket_descriptor);
+
+ /* Copy the Hyper-V packet out of the ring buffer */
+ desc_copy = (struct vmpacket_descriptor *)rbi->pkt_buffer;
+ memcpy(desc_copy, desc, pkt_len);
+
+ /*
+ * Hyper-V could still change len8 and offset8 after the earlier read.
+ * Ensure that desc_copy has legal values for len8 and offset8 that
+ * are consistent with the copy we just made
+ */
+ desc_copy->len8 = pkt_len >> 3;
+ desc_copy->offset8 = pkt_offset >> 3;
- return desc;
+ return desc_copy;
}
EXPORT_SYMBOL_GPL(hv_pkt_iter_first);
diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index f43b614f2345..a394f73b9821 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -860,6 +860,13 @@ static inline u32 netvsc_rqstor_size(unsigned long ringbytes)
ringbytes / NETVSC_MIN_IN_MSG_SIZE;
}
+#define NETVSC_MAX_XFER_PAGE_RANGES 375
+#define NETVSC_XFER_HEADER_SIZE(rng_cnt) \
+ (offsetof(struct vmtransfer_page_packet_header, ranges) + \
+ (rng_cnt) * sizeof(struct vmtransfer_page_range))
+#define NETVSC_MAX_PKT_SIZE (NETVSC_XFER_HEADER_SIZE(NETVSC_MAX_XFER_PAGE_RANGES) + \
+ sizeof(struct nvsp_message) + (sizeof(u32) * VRSS_SEND_TAB_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 79b907a29433..9585df459841 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -1473,6 +1473,8 @@ struct netvsc_device *netvsc_device_add(struct hv_device *device,
/* Open the channel */
device->channel->rqstor_size = netvsc_rqstor_size(netvsc_ring_bytes);
+ device->channel->max_pkt_size = NETVSC_MAX_PKT_SIZE;
+
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 10489ba44a09..6de0f4e0db7b 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -1115,6 +1115,8 @@ static void netvsc_sc_open(struct vmbus_channel *new_sc)
nvchan->channel = new_sc;
new_sc->rqstor_size = netvsc_rqstor_size(netvsc_ring_bytes);
+ new_sc->max_pkt_size = NETVSC_MAX_PKT_SIZE;
+
ret = vmbus_open(new_sc, netvsc_ring_bytes,
netvsc_ring_bytes, NULL, 0,
netvsc_channel_cb, nvchan);
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 6d2df1f0fe6d..fc259e2517ae 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -414,6 +414,14 @@ static void storvsc_on_channel_callback(void *context);
#define STORVSC_IDE_MAX_TARGETS 1
#define STORVSC_IDE_MAX_CHANNELS 1
+/*
+ * Upper bound on the size of a storvsc packet. vmscsi_size_delta is not
+ * included in the calculation because it is set after STORVSC_MAX_PKT_SIZE
+ * is used in storvsc_connect_to_vsp
+ */
+#define STORVSC_MAX_PKT_SIZE (sizeof(struct vmpacket_descriptor) +\
+ sizeof(struct vstor_packet))
+
struct storvsc_cmd_request {
struct scsi_cmnd *cmd;
@@ -698,6 +706,7 @@ static void handle_sc_creation(struct vmbus_channel *new_sc)
return;
memset(&props, 0, sizeof(struct vmstorage_channel_properties));
+ new_sc->max_pkt_size = STORVSC_MAX_PKT_SIZE;
/*
* The size of vmbus_requestor is an upper bound on the number of requests
@@ -1292,6 +1301,7 @@ static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size,
memset(&props, 0, sizeof(struct vmstorage_channel_properties));
+ device->channel->max_pkt_size = STORVSC_MAX_PKT_SIZE;
/*
* The size of vmbus_requestor is an upper bound on the number of requests
* that can be in-progress at any one time across all channels.
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index d8194924983d..3524d9e481c5 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -133,6 +133,10 @@ struct hv_ring_buffer_info {
* being freed while the ring buffer is being accessed.
*/
struct mutex ring_buffer_mutex;
+
+ /* Buffer that holds a copy of an incoming host packet */
+ void *pkt_buffer;
+ u32 pkt_buffer_size;
};
@@ -738,6 +742,8 @@ struct vmbus_device {
bool perf_device;
};
+#define VMBUS_DEFAULT_MAX_PKT_SIZE 4096
+
struct vmbus_channel {
struct list_head listentry;
@@ -959,6 +965,9 @@ struct vmbus_channel {
/* request/transaction ids for VMBus */
struct vmbus_requestor requestor;
u32 rqstor_size;
+
+ /* The max size of a packet on this channel */
+ u32 max_pkt_size;
};
u64 vmbus_next_request_id(struct vmbus_requestor *rqstor, u64 rqst_addr);
--
2.25.1
