user/sven/linux.git/drivers/vhost/net.c, branch v4.4.213

vhost_net: fix possible infinite loop

2019-09-06T08:18:12Z

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 4.4: - Both Tx modes are handled in one loop in handle_tx() - Adjust context] Signed-off-by: Ben Hutchings Signed-off-by: Sasha Levin

vhost: introduce vhost_exceeds_weight()

2019-09-06T08:18:12Z

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 4.4: - Drop changes to vhost_vsock - In vhost_net, both Tx modes are handled in one loop in handle_tx() - Adjust context] Signed-off-by: Ben Hutchings Signed-off-by: Sasha Levin

vhost_net: introduce vhost_exceeds_weight()

2019-09-06T08:18:12Z

commit 272f35cba53d088085e5952fd81d7a133ab90789 upstream. Signed-off-by: Jason Wang Signed-off-by: David S. Miller [bwh: Backported to 4.4: adjust context] Signed-off-by: Ben Hutchings Signed-off-by: Sasha Levin

vhost_net: use packet weight for rx handler, too

2019-09-06T08:18:11Z

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: Sasha Levin

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

2019-09-06T08:18:11Z

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: Sasha Levin

vhost_net: disable zerocopy by default

2019-08-04T07:34:46Z

[ 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_net: validate sock before trying to put its fd

2018-07-22T12:25:53Z

[ 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

vhost_net: stop device during reset owner

2018-02-16T19:09:38Z

[ Upstream commit 4cd879515d686849eec5f718aeac62a70b067d82 ] We don't stop device before reset owner, this means we could try to serve any virtqueue kick before reset dev->worker. This will result a warn since the work was pending at llist during owner resetting. Fix this by stopping device during owner reset. Reported-by: syzbot+eb17c6162478cc50632c@syzkaller.appspotmail.com Fixes: 3a4d5c94e9593 ("vhost_net: a kernel-level virtio server") Signed-off-by: Jason Wang Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

vhost: move features to core

2015-09-16T09:48:07Z

virtio 1 and any layout are core features, move them there. This fixes vhost test. Signed-off-by: Michael S. Tsirkin

new helper: msg_data_left()

2015-04-11T19:53:35Z

convert open-coded instances Signed-off-by: Al Viro