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authorAndres Beltran <lkmlabelt@gmail.com>2020-12-08 05:53:11 +0100
committerWei Liu <wei.liu@kernel.org>2021-02-05 09:55:42 +0000
commita8c3209998afb5c4941b49e35b513cea9050cb4a (patch)
tree78b3020b0631cd1ea476779988be0eacecd18d7a /drivers/hv
parent6ee1d745b7c9fd573fba142a2efdad76a9f1cb04 (diff)
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>
Diffstat (limited to 'drivers/hv')
-rw-r--r--drivers/hv/channel.c9
-rw-r--r--drivers/hv/hv_fcopy.c1
-rw-r--r--drivers/hv/hv_kvp.c1
-rw-r--r--drivers/hv/hyperv_vmbus.h2
-rw-r--r--drivers/hv/ring_buffer.c82
5 files changed, 80 insertions, 15 deletions
diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 6fb0c76bfbf8..0d63862d6551 100644
--- 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 5040d7e0cd9e..85784a9e6a36 100644
--- 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 754d35a25a1c..7d2a7b918847 100644
--- 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 9416e09ebd58..42f3d9d123a1 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 35833d4d1a1d..29e90477363a 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 = 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);
@@ -412,6 +423,22 @@ static u32 hv_pkt_iter_avail(const struct hv_ring_buffer_info *rbi)
}
/*
+ * 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
*
* If ring buffer is empty, returns NULL and no other action needed.
@@ -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);