Drivers: hv: vmbus: Copy packets sent by Hyper-V out of the ring buffer

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.

Signed-off-by: Andres Beltran <lkmlabelt@gmail.com>
Co-developed-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: netdev@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20201208045311.10244-1-parri.andrea@gmail.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 6fb0c76..0d63862 100644 (file)
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -597,12 +597,15 @@ 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/hv_fcopy.c b/drivers/hv/hv_fcopy.c
index 5040d7e..85784a9 100644 (file)
--- a/drivers/hv/hv_fcopy.c
+++ b/drivers/hv/hv_fcopy.c
@@ -329,6 +329,7 @@ int hv_fcopy_init(struct hv_util_service *srv)
 {
        recv_buffer = srv->recv_buffer;
        fcopy_transaction.recv_channel = srv->channel;
+       fcopy_transaction.recv_channel->max_pkt_size = HV_HYP_PAGE_SIZE * 2;
 
        /*
         * When this driver loads, the user level daemon that

diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c
index 754d35a..7d2a7b9 100644 (file)
--- a/drivers/hv/hv_kvp.c
+++ b/drivers/hv/hv_kvp.c
@@ -741,6 +741,7 @@ hv_kvp_init(struct hv_util_service *srv)
 {
        recv_buffer = srv->recv_buffer;
        kvp_transaction.recv_channel = srv->channel;
+       kvp_transaction.recv_channel->max_pkt_size = HV_HYP_PAGE_SIZE * 4;
 
        /*
         * When this driver loads, the user level daemon that

diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 9416e09..42f3d9d 100644 (file)
--- 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 35833d4..29e9047 100644 (file)
--- 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 = kzalloc(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. */
@@ -385,7 +396,7 @@ int hv_ringbuffer_read(struct vmbus_channel *channel,
        memcpy(buffer, (const char *)desc + offset, packetlen);
 
        /* Advance ring index to next packet descriptor */
-       __hv_pkt_iter_next(channel, desc);
+       __hv_pkt_iter_next(channel, desc, true);
 
        /* Notify host of update */
        hv_pkt_iter_close(channel);
@@ -411,6 +422,22 @@ static u32 hv_pkt_iter_avail(const struct hv_ring_buffer_info *rbi)
                return (rbi->ring_datasize - priv_read_loc) + write_loc;
 }
 
+/*
+ * Get first vmbus packet without copying it out of the ring buffer
+ */
+struct vmpacket_descriptor *hv_pkt_iter_first_raw(struct vmbus_channel *channel)
+{
+       struct hv_ring_buffer_info *rbi = &channel->inbound;
+
+       hv_debug_delay_test(channel, MESSAGE_DELAY);
+
+       if (hv_pkt_iter_avail(rbi) < sizeof(struct vmpacket_descriptor))
+               return NULL;
+
+       return (struct vmpacket_descriptor *)(hv_get_ring_buffer(rbi) + rbi->priv_read_index);
+}
+EXPORT_SYMBOL_GPL(hv_pkt_iter_first_raw);
+
 /*
  * Get first vmbus packet from ring buffer after read_index
  *
@@ -419,17 +446,49 @@ static u32 hv_pkt_iter_avail(const struct hv_ring_buffer_info *rbi)
 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, *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))
+       desc = hv_pkt_iter_first_raw(channel);
+       if (!desc)
                return NULL;
 
-       desc = hv_get_ring_buffer(rbi) + rbi->priv_read_index;
-       if (desc)
-               prefetch((char *)desc + (desc->len8 << 3));
+       bytes_avail = min(rbi->pkt_buffer_size, hv_pkt_iter_avail(rbi));
+
+       /*
+        * 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 (pkt_len < sizeof(struct vmpacket_descriptor) || pkt_len > bytes_avail)
+               pkt_len = bytes_avail;
+
+       /*
+        * If pkt_offset 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);
 
@@ -441,7 +500,8 @@ EXPORT_SYMBOL_GPL(hv_pkt_iter_first);
  */
 struct vmpacket_descriptor *
 __hv_pkt_iter_next(struct vmbus_channel *channel,
-                  const struct vmpacket_descriptor *desc)
+                  const struct vmpacket_descriptor *desc,
+                  bool copy)
 {
        struct hv_ring_buffer_info *rbi = &channel->inbound;
        u32 packetlen = desc->len8 << 3;
@@ -454,7 +514,7 @@ __hv_pkt_iter_next(struct vmbus_channel *channel,
                rbi->priv_read_index -= dsize;
 
        /* more data? */
-       return hv_pkt_iter_first(channel);
+       return copy ? hv_pkt_iter_first(channel) : hv_pkt_iter_first_raw(channel);
 }
 EXPORT_SYMBOL_GPL(__hv_pkt_iter_next);
 

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 2a87cfa..7ea6936 100644 (file)
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -860,9 +860,12 @@ 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 */

diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 2350342..1510a23 100644 (file)
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -1530,6 +1530,8 @@ 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 598713c..7e6dee2 100644 (file)
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -1174,6 +1174,8 @@ 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 2e4fa77..7e59284 100644 (file)
--- 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
@@ -1280,6 +1289,7 @@ 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 5ddb479..fbae840 100644 (file)
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -181,6 +181,10 @@ 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;
 };
 
 
@@ -787,6 +791,8 @@ struct vmbus_device {
        bool perf_device;
 };
 
+#define VMBUS_DEFAULT_MAX_PKT_SIZE 4096
+
 struct vmbus_channel {
        struct list_head listentry;
 
@@ -1008,6 +1014,9 @@ 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);
@@ -1642,32 +1651,55 @@ static inline u32 hv_pkt_datalen(const struct vmpacket_descriptor *desc)
 }
 
 
+struct vmpacket_descriptor *
+hv_pkt_iter_first_raw(struct vmbus_channel *channel);
+
 struct vmpacket_descriptor *
 hv_pkt_iter_first(struct vmbus_channel *channel);
 
 struct vmpacket_descriptor *
 __hv_pkt_iter_next(struct vmbus_channel *channel,
-                  const struct vmpacket_descriptor *pkt);
+                  const struct vmpacket_descriptor *pkt,
+                  bool copy);
 
 void hv_pkt_iter_close(struct vmbus_channel *channel);
 
-/*
- * Get next packet descriptor from iterator
- * If at end of list, return NULL and update host.
- */
 static inline struct vmpacket_descriptor *
-hv_pkt_iter_next(struct vmbus_channel *channel,
-                const struct vmpacket_descriptor *pkt)
+hv_pkt_iter_next_pkt(struct vmbus_channel *channel,
+                    const struct vmpacket_descriptor *pkt,
+                    bool copy)
 {
        struct vmpacket_descriptor *nxt;
 
-       nxt = __hv_pkt_iter_next(channel, pkt);
+       nxt = __hv_pkt_iter_next(channel, pkt, copy);
        if (!nxt)
                hv_pkt_iter_close(channel);
 
        return nxt;
 }
 
+/*
+ * Get next packet descriptor without copying it out of the ring buffer
+ * If at end of list, return NULL and update host.
+ */
+static inline struct vmpacket_descriptor *
+hv_pkt_iter_next_raw(struct vmbus_channel *channel,
+                    const struct vmpacket_descriptor *pkt)
+{
+       return hv_pkt_iter_next_pkt(channel, pkt, false);
+}
+
+/*
+ * Get next packet descriptor from iterator
+ * If at end of list, return NULL and update host.
+ */
+static inline struct vmpacket_descriptor *
+hv_pkt_iter_next(struct vmbus_channel *channel,
+                const struct vmpacket_descriptor *pkt)
+{
+       return hv_pkt_iter_next_pkt(channel, pkt, true);
+}
+
 #define foreach_vmbus_pkt(pkt, channel) \
        for (pkt = hv_pkt_iter_first(channel); pkt; \
            pkt = hv_pkt_iter_next(channel, pkt))

diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
index 630b851..cd8b7c1 100644 (file)
--- a/net/vmw_vsock/hyperv_transport.c
+++ b/net/vmw_vsock/hyperv_transport.c
@@ -600,7 +600,7 @@ static ssize_t hvs_stream_dequeue(struct vsock_sock *vsk, struct msghdr *msg,
                return -EOPNOTSUPP;
 
        if (need_refill) {
-               hvs->recv_desc = hv_pkt_iter_first(hvs->chan);
+               hvs->recv_desc = hv_pkt_iter_first_raw(hvs->chan);
                ret = hvs_update_recv_data(hvs);
                if (ret)
                        return ret;
@@ -614,7 +614,7 @@ static ssize_t hvs_stream_dequeue(struct vsock_sock *vsk, struct msghdr *msg,
 
        hvs->recv_data_len -= to_read;
        if (hvs->recv_data_len == 0) {
-               hvs->recv_desc = hv_pkt_iter_next(hvs->chan, hvs->recv_desc);
+               hvs->recv_desc = hv_pkt_iter_next_raw(hvs->chan, hvs->recv_desc);
                if (hvs->recv_desc) {
                        ret = hvs_update_recv_data(hvs);
                        if (ret)