linux-stable.git/drivers/vhost/net.c, branch linux-4.9.y

vhost_net: fix ubuf refcount incorrectly when sendmsg fails

2021-01-12T18:49:02+00:00

[ Upstream commit 01e31bea7e622f1890c274f4aaaaf8bccd296aa5 ]

Currently the vhost_zerocopy_callback() maybe be called to decrease
the refcount when sendmsg fails in tun. The error handling in vhost
handle_tx_zerocopy() will try to decrease the same refcount again.
This is wrong. To fix this issue, we only call vhost_net_ubuf_put()
when vq->heads[nvq->desc].len == VHOST_DMA_IN_PROGRESS.

Fixes: bab632d69ee4 ("vhost: vhost TX zero-copy support")
Signed-off-by: Yunjian Wang 
Acked-by: Willem de Bruijn 
Acked-by: Michael S. Tsirkin 
Acked-by: Jason Wang 
Link: https://lore.kernel.org/r/1609207308-20544-1-git-send-email-wangyunjian@huawei.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

vhost: Check docket sk_family instead of call getname

2020-03-11T06:53:08+00:00

[ Upstream commit 42d84c8490f9f0931786f1623191fcab397c3d64 ]

Doing so, we save one call to get data we already have in the struct.

Also, since there is no guarantee that getname use sockaddr_ll
parameter beyond its size, we add a little bit of security here.
It should do not do beyond MAX_ADDR_LEN, but syzbot found that
ax25_getname writes more (72 bytes, the size of full_sockaddr_ax25,
versus 20 + 32 bytes of sockaddr_ll + MAX_ADDR_LEN in syzbot repro).

Fixes: 3a4d5c94e9593 ("vhost_net: a kernel-level virtio server")
Reported-by: syzbot+f2a62d07a5198c819c7b@syzkaller.appspotmail.com
Signed-off-by: Eugenio Pérez 
Acked-by: Michael S. Tsirkin 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

vhost_net: fix possible infinite loop

2019-08-25T08:51:42+00:00

commit e2412c07f8f3040593dfb88207865a3cd58680c0 upstream.

When the rx buffer is too small for a packet, we will discard the vq
descriptor and retry it for the next packet:

while ((sock_len = vhost_net_rx_peek_head_len(net, sock->sk,
					      &busyloop_intr))) {
...
	/* On overrun, truncate and discard */
	if (unlikely(headcount > UIO_MAXIOV)) {
		iov_iter_init(&msg.msg_iter, READ, vq->iov, 1, 1);
		err = sock->ops->recvmsg(sock, &msg,
					 1, MSG_DONTWAIT | MSG_TRUNC);
		pr_debug("Discarded rx packet: len %zd\n", sock_len);
		continue;
	}
...
}

This makes it possible to trigger a infinite while..continue loop
through the co-opreation of two VMs like:

1) Malicious VM1 allocate 1 byte rx buffer and try to slow down the
   vhost process as much as possible e.g using indirect descriptors or
   other.
2) Malicious VM2 generate packets to VM1 as fast as possible

Fixing this by checking against weight at the end of RX and TX
loop. This also eliminate other similar cases when:

- userspace is consuming the packets in the meanwhile
- theoretical TOCTOU attack if guest moving avail index back and forth
  to hit the continue after vhost find guest just add new buffers

This addresses CVE-2019-3900.

Fixes: d8316f3991d20 ("vhost: fix total length when packets are too short")
Fixes: 3a4d5c94e9593 ("vhost_net: a kernel-level virtio server")
Signed-off-by: Jason Wang 
Reviewed-by: Stefan Hajnoczi 
Signed-off-by: Michael S. Tsirkin 
[bwh: Backported to 4.9:
 - Both Tx modes are handled in one loop in handle_tx()
 - Adjust context]
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

vhost: introduce vhost_exceeds_weight()

2019-08-25T08:51:41+00:00

commit e82b9b0727ff6d665fff2d326162b460dded554d upstream.

We used to have vhost_exceeds_weight() for vhost-net to:

- prevent vhost kthread from hogging the cpu
- balance the time spent between TX and RX

This function could be useful for vsock and scsi as well. So move it
to vhost.c. Device must specify a weight which counts the number of
requests, or it can also specific a byte_weight which counts the
number of bytes that has been processed.

Signed-off-by: Jason Wang 
Reviewed-by: Stefan Hajnoczi 
Signed-off-by: Michael S. Tsirkin 
[bwh: Backported to 4.9:
 - In vhost_net, both Tx modes are handled in one loop in handle_tx()
 - Adjust context]
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

vhost_net: introduce vhost_exceeds_weight()

2019-08-25T08:51:41+00:00

commit 272f35cba53d088085e5952fd81d7a133ab90789 upstream.

Signed-off-by: Jason Wang 
Signed-off-by: David S. Miller 
[bwh: Backported to 4.9: adjust context]
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

vhost_net: use packet weight for rx handler, too

2019-08-25T08:51:41+00:00

commit db688c24eada63b1efe6d0d7d835e5c3bdd71fd3 upstream.

Similar to commit a2ac99905f1e ("vhost-net: set packet weight of
tx polling to 2 * vq size"), we need a packet-based limit for
handler_rx, too - elsewhere, under rx flood with small packets,
tx can be delayed for a very long time, even without busypolling.

The pkt limit applied to handle_rx must be the same applied by
handle_tx, or we will get unfair scheduling between rx and tx.
Tying such limit to the queue length makes it less effective for
large queue length values and can introduce large process
scheduler latencies, so a constant valued is used - likewise
the existing bytes limit.

The selected limit has been validated with PVP[1] performance
test with different queue sizes:

queue size		256	512	1024

baseline		366	354	362
weight 128		715	723	670
weight 256		740	745	733
weight 512		600	460	583
weight 1024		423	427	418

A packet weight of 256 gives peek performances in under all the
tested scenarios.

No measurable regression in unidirectional performance tests has
been detected.

[1] https://developers.redhat.com/blog/2017/06/05/measuring-and-comparing-open-vswitch-performance/

Signed-off-by: Paolo Abeni 
Acked-by: Jason Wang 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

vhost-net: set packet weight of tx polling to 2 * vq size

2019-08-25T08:51:41+00:00

commit a2ac99905f1ea8b15997a6ec39af69aa28a3653b upstream.

handle_tx will delay rx for tens or even hundreds of milliseconds when tx busy
polling udp packets with small length(e.g. 1byte udp payload), because setting
VHOST_NET_WEIGHT takes into account only sent-bytes but no single packet length.

Ping-Latencies shown below were tested between two Virtual Machines using
netperf (UDP_STREAM, len=1), and then another machine pinged the client:

vq size=256
Packet-Weight   Ping-Latencies(millisecond)
                   min      avg       max
Origin           3.319   18.489    57.303
64               1.643    2.021     2.552
128              1.825    2.600     3.224
256              1.997    2.710     4.295
512              1.860    3.171     4.631
1024             2.002    4.173     9.056
2048             2.257    5.650     9.688
4096             2.093    8.508    15.943

vq size=512
Packet-Weight   Ping-Latencies(millisecond)
                   min      avg       max
Origin           6.537   29.177    66.245
64               2.798    3.614     4.403
128              2.861    3.820     4.775
256              3.008    4.018     4.807
512              3.254    4.523     5.824
1024             3.079    5.335     7.747
2048             3.944    8.201    12.762
4096             4.158   11.057    19.985

Seems pretty consistent, a small dip at 2 VQ sizes.
Ring size is a hint from device about a burst size it can tolerate. Based on
benchmarks, set the weight to 2 * vq size.

To evaluate this change, another tests were done using netperf(RR, TX) between
two machines with Intel(R) Xeon(R) Gold 6133 CPU @ 2.50GHz, and vq size was
tweaked through qemu. Results shown below does not show obvious changes.

vq size=256 TCP_RR                vq size=512 TCP_RR
size/sessions/+thu%/+normalize%   size/sessions/+thu%/+normalize%
   1/       1/  -7%/        -2%      1/       1/   0%/        -2%
   1/       4/  +1%/         0%      1/       4/  +1%/         0%
   1/       8/  +1%/        -2%      1/       8/   0%/        +1%
  64/       1/  -6%/         0%     64/       1/  +7%/        +3%
  64/       4/   0%/        +2%     64/       4/  -1%/        +1%
  64/       8/   0%/         0%     64/       8/  -1%/        -2%
 256/       1/  -3%/        -4%    256/       1/  -4%/        -2%
 256/       4/  +3%/        +4%    256/       4/  +1%/        +2%
 256/       8/  +2%/         0%    256/       8/  +1%/        -1%

vq size=256 UDP_RR                vq size=512 UDP_RR
size/sessions/+thu%/+normalize%   size/sessions/+thu%/+normalize%
   1/       1/  -5%/        +1%      1/       1/  -3%/        -2%
   1/       4/  +4%/        +1%      1/       4/  -2%/        +2%
   1/       8/  -1%/        -1%      1/       8/  -1%/         0%
  64/       1/  -2%/        -3%     64/       1/  +1%/        +1%
  64/       4/  -5%/        -1%     64/       4/  +2%/         0%
  64/       8/   0%/        -1%     64/       8/  -2%/        +1%
 256/       1/  +7%/        +1%    256/       1/  -7%/         0%
 256/       4/  +1%/        +1%    256/       4/  -3%/        -4%
 256/       8/  +2%/        +2%    256/       8/  +1%/        +1%

vq size=256 TCP_STREAM            vq size=512 TCP_STREAM
size/sessions/+thu%/+normalize%   size/sessions/+thu%/+normalize%
  64/       1/   0%/        -3%     64/       1/   0%/         0%
  64/       4/  +3%/        -1%     64/       4/  -2%/        +4%
  64/       8/  +9%/        -4%     64/       8/  -1%/        +2%
 256/       1/  +1%/        -4%    256/       1/  +1%/        +1%
 256/       4/  -1%/        -1%    256/       4/  -3%/         0%
 256/       8/  +7%/        +5%    256/       8/  -3%/         0%
 512/       1/  +1%/         0%    512/       1/  -1%/        -1%
 512/       4/  +1%/        -1%    512/       4/   0%/         0%
 512/       8/  +7%/        -5%    512/       8/  +6%/        -1%
1024/       1/   0%/        -1%   1024/       1/   0%/        +1%
1024/       4/  +3%/         0%   1024/       4/  +1%/         0%
1024/       8/  +8%/        +5%   1024/       8/  -1%/         0%
2048/       1/  +2%/        +2%   2048/       1/  -1%/         0%
2048/       4/  +1%/         0%   2048/       4/   0%/        -1%
2048/       8/  -2%/         0%   2048/       8/   5%/        -1%
4096/       1/  -2%/         0%   4096/       1/  -2%/         0%
4096/       4/  +2%/         0%   4096/       4/   0%/         0%
4096/       8/  +9%/        -2%   4096/       8/  -5%/        -1%

Acked-by: Michael S. Tsirkin 
Signed-off-by: Haibin Zhang 
Signed-off-by: Yunfang Tai 
Signed-off-by: Lidong Chen 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

vhost_net: disable zerocopy by default

2019-08-04T07:33:20+00:00

[ Upstream commit 098eadce3c622c07b328d0a43dda379b38cf7c5e ]

Vhost_net was known to suffer from HOL[1] issues which is not easy to
fix. Several downstream disable the feature by default. What's more,
the datapath was split and datacopy path got the support of batching
and XDP support recently which makes it faster than zerocopy part for
small packets transmission.

It looks to me that disable zerocopy by default is more
appropriate. It cold be enabled by default again in the future if we
fix the above issues.

[1] https://patchwork.kernel.org/patch/3787671/

Signed-off-by: Jason Wang 
Acked-by: Michael S. Tsirkin 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

vhost: log dirty page correctly

2019-01-31T07:12:33+00:00

[ Upstream commit cc5e710759470bc7f3c61d11fd54586f15fdbdf4 ]

Vhost dirty page logging API is designed to sync through GPA. But we
try to log GIOVA when device IOTLB is enabled. This is wrong and may
lead to missing data after migration.

To solve this issue, when logging with device IOTLB enabled, we will:

1) reuse the device IOTLB translation result of GIOVA->HVA mapping to
   get HVA, for writable descriptor, get HVA through iovec. For used
   ring update, translate its GIOVA to HVA
2) traverse the GPA->HVA mapping to get the possible GPA and log
   through GPA. Pay attention this reverse mapping is not guaranteed
   to be unique, so we should log each possible GPA in this case.

This fix the failure of scp to guest during migration. In -next, we
will probably support passing GIOVA->GPA instead of GIOVA->HVA.

Fixes: 6b1e6cc7855b ("vhost: new device IOTLB API")
Reported-by: Jintack Lim 
Cc: Jintack Lim 
Signed-off-by: Jason Wang 
Acked-by: Michael S. Tsirkin 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

vhost_net: validate sock before trying to put its fd

2018-07-22T12:27:38+00:00

[ Upstream commit b8f1f65882f07913157c44673af7ec0b308d03eb ]

Sock will be NULL if we pass -1 to vhost_net_set_backend(), but when
we meet errors during ubuf allocation, the code does not check for
NULL before calling sockfd_put(), this will lead NULL
dereferencing. Fixing by checking sock pointer before.

Fixes: bab632d69ee4 ("vhost: vhost TX zero-copy support")
Reported-by: Dan Carpenter 
Signed-off-by: Jason Wang 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman