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-rw-r--r--tcp_vu.c513
1 files changed, 513 insertions, 0 deletions
diff --git a/tcp_vu.c b/tcp_vu.c
new file mode 100644
index 0000000..04a10b5
--- /dev/null
+++ b/tcp_vu.c
@@ -0,0 +1,513 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* tcp_vu.c - TCP L2 vhost-user management functions
+ *
+ * Copyright Red Hat
+ * Author: Laurent Vivier <lvivier@redhat.com>
+ */
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include <netinet/ip.h>
+#include <netinet/tcp.h>
+
+#include <sys/socket.h>
+
+#include <linux/virtio_net.h>
+
+#include "util.h"
+#include "ip.h"
+#include "passt.h"
+#include "siphash.h"
+#include "inany.h"
+#include "vhost_user.h"
+#include "tcp.h"
+#include "pcap.h"
+#include "flow.h"
+#include "tcp_conn.h"
+#include "flow_table.h"
+#include "tcp_vu.h"
+#include "tap.h"
+#include "tcp_internal.h"
+#include "checksum.h"
+#include "vu_common.h"
+
+static struct iovec iov_vu[VIRTQUEUE_MAX_SIZE + 1];
+static struct vu_virtq_element elem[VIRTQUEUE_MAX_SIZE];
+
+/**
+ * tcp_vu_hdrlen() - return the size of the header in level 2 frame (TCP)
+ * @v6: Set for IPv6 packet
+ *
+ * Return: Return the size of the header
+ */
+static size_t tcp_vu_hdrlen(bool v6)
+{
+ size_t hdrlen;
+
+ hdrlen = sizeof(struct virtio_net_hdr_mrg_rxbuf) +
+ sizeof(struct ethhdr) + sizeof(struct tcphdr);
+
+ if (v6)
+ hdrlen += sizeof(struct ipv6hdr);
+ else
+ hdrlen += sizeof(struct iphdr);
+
+ return hdrlen;
+}
+
+/**
+ * tcp_vu_update_check() - Calculate TCP checksum
+ * @tapside: Address information for one side of the flow
+ * @iov: Pointer to the array of IO vectors
+ * @iov_used: Length of the array
+ */
+static void tcp_vu_update_check(const struct flowside *tapside,
+ struct iovec *iov, int iov_used)
+{
+ char *base = iov[0].iov_base;
+
+ if (inany_v4(&tapside->oaddr)) {
+ const struct iphdr *iph = vu_ip(base);
+
+ tcp_update_check_tcp4(iph, iov, iov_used,
+ (char *)vu_payloadv4(base) - base);
+ } else {
+ const struct ipv6hdr *ip6h = vu_ip(base);
+
+ tcp_update_check_tcp6(ip6h, iov, iov_used,
+ (char *)vu_payloadv6(base) - base);
+ }
+}
+
+/**
+ * tcp_vu_send_flag() - Send segment with flags to vhost-user (no payload)
+ * @c: Execution context
+ * @conn: Connection pointer
+ * @flags: TCP flags: if not set, send segment only if ACK is due
+ *
+ * Return: negative error code on connection reset, 0 otherwise
+ */
+int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags)
+{
+ struct vu_dev *vdev = c->vdev;
+ struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
+ const struct flowside *tapside = TAPFLOW(conn);
+ size_t l2len, l4len, optlen, hdrlen;
+ struct vu_virtq_element flags_elem[2];
+ struct iovec flags_iov[2];
+ struct ethhdr *eh;
+ int elem_cnt;
+ int nb_ack;
+ int ret;
+
+ hdrlen = tcp_vu_hdrlen(CONN_V6(conn));
+
+ vu_set_element(&flags_elem[0], NULL, &flags_iov[0]);
+
+ elem_cnt = vu_collect(vdev, vq, &flags_elem[0], 1,
+ hdrlen + sizeof(struct tcp_syn_opts), NULL);
+ if (elem_cnt != 1)
+ return -1;
+
+ vu_set_vnethdr(vdev, flags_elem[0].in_sg[0].iov_base, 1);
+
+ eh = vu_eth(flags_elem[0].in_sg[0].iov_base);
+
+ memcpy(eh->h_dest, c->guest_mac, sizeof(eh->h_dest));
+ memcpy(eh->h_source, c->our_tap_mac, sizeof(eh->h_source));
+
+ if (CONN_V4(conn)) {
+ struct tcp_payload_t *payload;
+ struct iphdr *iph;
+ uint32_t seq;
+
+ eh->h_proto = htons(ETH_P_IP);
+
+ iph = vu_ip(flags_elem[0].in_sg[0].iov_base);
+ *iph = (struct iphdr)L2_BUF_IP4_INIT(IPPROTO_TCP);
+
+ payload = vu_payloadv4(flags_elem[0].in_sg[0].iov_base);
+ memset(&payload->th, 0, sizeof(payload->th));
+ payload->th.doff = offsetof(struct tcp_payload_t, data) / 4;
+ payload->th.ack = 1;
+
+ seq = conn->seq_to_tap;
+ ret = tcp_prepare_flags(c, conn, flags, &payload->th,
+ (struct tcp_syn_opts *)payload->data,
+ &optlen);
+ if (ret <= 0) {
+ vu_queue_rewind(vq, 1);
+ return ret;
+ }
+
+ l4len = tcp_fill_headers4(conn, NULL, iph, payload, optlen,
+ NULL, seq, true);
+ l2len = sizeof(*iph);
+ } else {
+ struct tcp_payload_t *payload;
+ struct ipv6hdr *ip6h;
+ uint32_t seq;
+
+ eh->h_proto = htons(ETH_P_IPV6);
+
+ ip6h = vu_ip(flags_elem[0].in_sg[0].iov_base);
+ *ip6h = (struct ipv6hdr)L2_BUF_IP6_INIT(IPPROTO_TCP);
+
+ payload = vu_payloadv6(flags_elem[0].in_sg[0].iov_base);
+ memset(&payload->th, 0, sizeof(payload->th));
+ payload->th.doff = offsetof(struct tcp_payload_t, data) / 4;
+ payload->th.ack = 1;
+
+ seq = conn->seq_to_tap;
+ ret = tcp_prepare_flags(c, conn, flags, &payload->th,
+ (struct tcp_syn_opts *)payload->data,
+ &optlen);
+ if (ret <= 0) {
+ vu_queue_rewind(vq, 1);
+ return ret;
+ }
+
+ l4len = tcp_fill_headers6(conn, NULL, ip6h, payload, optlen,
+ seq, true);
+ l2len = sizeof(*ip6h);
+ }
+ l2len += l4len + sizeof(struct ethhdr);
+
+ flags_elem[0].in_sg[0].iov_len = l2len +
+ sizeof(struct virtio_net_hdr_mrg_rxbuf);
+ if (*c->pcap) {
+ tcp_vu_update_check(tapside, &flags_elem[0].in_sg[0], 1);
+ pcap_iov(&flags_elem[0].in_sg[0], 1,
+ sizeof(struct virtio_net_hdr_mrg_rxbuf));
+ }
+ nb_ack = 1;
+
+ if (flags & DUP_ACK) {
+ vu_set_element(&flags_elem[1], NULL, &flags_iov[1]);
+
+ elem_cnt = vu_collect(vdev, vq, &flags_elem[1], 1,
+ flags_elem[0].in_sg[0].iov_len, NULL);
+ if (elem_cnt == 1) {
+ memcpy(flags_elem[1].in_sg[0].iov_base,
+ flags_elem[0].in_sg[0].iov_base,
+ flags_elem[0].in_sg[0].iov_len);
+ nb_ack++;
+
+ if (*c->pcap)
+ pcap_iov(&flags_elem[1].in_sg[0], 1, 0);
+ }
+ }
+
+ vu_flush(vdev, vq, flags_elem, nb_ack);
+
+ return 0;
+}
+
+/** tcp_vu_sock_recv() - Receive datastream from socket into vhost-user buffers
+ * @c: Execution context
+ * @conn: Connection pointer
+ * @v6: Set for IPv6 connections
+ * @already_sent: Number of bytes already sent
+ * @fillsize: Number of bytes we can receive
+ * @iov_cnt: number of iov (output)
+ *
+ * Return: Number of iov entries used to store the data
+ */
+static ssize_t tcp_vu_sock_recv(const struct ctx *c,
+ const struct tcp_tap_conn *conn, bool v6,
+ uint32_t already_sent, size_t fillsize,
+ int *iov_cnt)
+{
+ struct vu_dev *vdev = c->vdev;
+ struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
+ struct msghdr mh_sock = { 0 };
+ uint16_t mss = MSS_GET(conn);
+ int s = conn->sock;
+ size_t hdrlen;
+ int elem_cnt;
+ ssize_t ret;
+
+ *iov_cnt = 0;
+
+ hdrlen = tcp_vu_hdrlen(v6);
+
+ vu_init_elem(elem, &iov_vu[1], VIRTQUEUE_MAX_SIZE);
+
+ elem_cnt = 0;
+
+ while (fillsize > 0 && elem_cnt < VIRTQUEUE_MAX_SIZE) {
+ struct iovec *iov;
+ size_t frame_size;
+ int cnt;
+
+ if (mss > fillsize)
+ mss = fillsize;
+
+ cnt = vu_collect(vdev, vq, &elem[elem_cnt],
+ VIRTQUEUE_MAX_SIZE - elem_cnt,
+ mss + hdrlen, &frame_size);
+ if (cnt == 0)
+ break;
+
+ frame_size -= hdrlen;
+ iov = &elem[elem_cnt].in_sg[0];
+ iov->iov_base = (char *)iov->iov_base + hdrlen;
+ iov->iov_len -= hdrlen;
+
+ fillsize -= frame_size;
+ elem_cnt += cnt;
+
+ /* All the frames must have the same size (except the last one),
+ * otherwise we will no able to scan the iov array
+ * to find iov entries with headers
+ * (headers are spread every frame_size in the the array
+ */
+ if (frame_size < mss)
+ break;
+ }
+
+ if (peek_offset_cap) {
+ mh_sock.msg_iov = iov_vu + 1;
+ mh_sock.msg_iovlen = elem_cnt;
+ } else {
+ iov_vu[0].iov_base = tcp_buf_discard;
+ iov_vu[0].iov_len = already_sent;
+
+ mh_sock.msg_iov = iov_vu;
+ mh_sock.msg_iovlen = elem_cnt + 1;
+ }
+
+ do
+ ret = recvmsg(s, &mh_sock, MSG_PEEK);
+ while (ret < 0 && errno == EINTR);
+
+ *iov_cnt = elem_cnt;
+
+ return ret;
+}
+
+/**
+ * tcp_vu_prepare() - Prepare the frame header
+ * @c: Execution context
+ * @conn: Connection pointer
+ * @first: Pointer to the array of IO vectors
+ * @dlen: Packet data length
+ * @check: Checksum, if already known
+ */
+static void tcp_vu_prepare(const struct ctx *c,
+ struct tcp_tap_conn *conn, struct iovec *first,
+ size_t dlen, const uint16_t **check)
+{
+ const struct flowside *toside = TAPFLOW(conn);
+ char *base = first->iov_base;
+ struct ethhdr *eh;
+
+ /* we guess the first iovec provided by the guest can embed
+ * all the headers needed by L2 frame
+ */
+
+ eh = vu_eth(base);
+
+ memcpy(eh->h_dest, c->guest_mac, sizeof(eh->h_dest));
+ memcpy(eh->h_source, c->our_tap_mac, sizeof(eh->h_source));
+
+ /* initialize header */
+ if (inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr)) {
+ struct tcp_payload_t *payload;
+ struct iphdr *iph;
+
+ ASSERT(first[0].iov_len >= tcp_vu_hdrlen(false));
+
+ eh->h_proto = htons(ETH_P_IP);
+
+ iph = vu_ip(base);
+ *iph = (struct iphdr)L2_BUF_IP4_INIT(IPPROTO_TCP);
+ payload = vu_payloadv4(base);
+ memset(&payload->th, 0, sizeof(payload->th));
+ payload->th.doff = offsetof(struct tcp_payload_t, data) / 4;
+ payload->th.ack = 1;
+
+ tcp_fill_headers4(conn, NULL, iph, payload, dlen,
+ *check, conn->seq_to_tap, true);
+ *check = &iph->check;
+ } else {
+ struct tcp_payload_t *payload;
+ struct ipv6hdr *ip6h;
+
+ ASSERT(first[0].iov_len >= tcp_vu_hdrlen(true));
+
+ eh->h_proto = htons(ETH_P_IPV6);
+
+ ip6h = vu_ip(base);
+ *ip6h = (struct ipv6hdr)L2_BUF_IP6_INIT(IPPROTO_TCP);
+
+ payload = vu_payloadv6(base);
+ memset(&payload->th, 0, sizeof(payload->th));
+ payload->th.doff = offsetof(struct tcp_payload_t, data) / 4;
+ payload->th.ack = 1;
+
+ tcp_fill_headers6(conn, NULL, ip6h, payload, dlen,
+ conn->seq_to_tap, true);
+ }
+}
+
+/**
+ * tcp_vu_data_from_sock() - Handle new data from socket, queue to vhost-user,
+ * in window
+ * @c: Execution context
+ * @conn: Connection pointer
+ *
+ * Return: Negative on connection reset, 0 otherwise
+ */
+int tcp_vu_data_from_sock(const struct ctx *c, struct tcp_tap_conn *conn)
+{
+ uint32_t wnd_scaled = conn->wnd_from_tap << conn->ws_from_tap;
+ struct vu_dev *vdev = c->vdev;
+ struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
+ const struct flowside *tapside = TAPFLOW(conn);
+ uint16_t mss = MSS_GET(conn);
+ size_t hdrlen, fillsize;
+ int i, iov_cnt, iov_used;
+ int v6 = CONN_V6(conn);
+ uint32_t already_sent = 0;
+ const uint16_t *check;
+ struct iovec *first;
+ int frame_size;
+ int num_buffers;
+ ssize_t len;
+
+ if (!vu_queue_enabled(vq) || !vu_queue_started(vq)) {
+ flow_err(conn,
+ "Got packet, but RX virtqueue not usable yet");
+ return 0;
+ }
+
+ already_sent = conn->seq_to_tap - conn->seq_ack_from_tap;
+
+ if (SEQ_LT(already_sent, 0)) {
+ /* RFC 761, section 2.1. */
+ flow_trace(conn, "ACK sequence gap: ACK for %u, sent: %u",
+ conn->seq_ack_from_tap, conn->seq_to_tap);
+ conn->seq_to_tap = conn->seq_ack_from_tap;
+ already_sent = 0;
+ if (tcp_set_peek_offset(conn->sock, 0)) {
+ tcp_rst(c, conn);
+ return -1;
+ }
+ }
+
+ if (!wnd_scaled || already_sent >= wnd_scaled) {
+ conn_flag(c, conn, STALLED);
+ conn_flag(c, conn, ACK_FROM_TAP_DUE);
+ return 0;
+ }
+
+ /* Set up buffer descriptors we'll fill completely and partially. */
+
+ fillsize = wnd_scaled - already_sent;
+
+ /* collect the buffers from vhost-user and fill them with the
+ * data from the socket
+ */
+ len = tcp_vu_sock_recv(c, conn, v6, already_sent, fillsize, &iov_cnt);
+ if (len < 0) {
+ vu_queue_rewind(vq, iov_cnt);
+ if (errno != EAGAIN && errno != EWOULDBLOCK) {
+ tcp_rst(c, conn);
+ return -errno;
+ }
+ return 0;
+ }
+
+ if (!len) {
+ vu_queue_rewind(vq, iov_cnt);
+ if ((conn->events & (SOCK_FIN_RCVD | TAP_FIN_SENT)) == SOCK_FIN_RCVD) {
+ int ret = tcp_vu_send_flag(c, conn, FIN | ACK);
+ if (ret) {
+ tcp_rst(c, conn);
+ return ret;
+ }
+
+ conn_event(c, conn, TAP_FIN_SENT);
+ }
+
+ return 0;
+ }
+
+ if (!peek_offset_cap)
+ len -= already_sent;
+
+ if (len <= 0) {
+ vu_queue_rewind(vq, iov_cnt);
+ conn_flag(c, conn, STALLED);
+ return 0;
+ }
+
+ conn_flag(c, conn, ~STALLED);
+
+ /* Likely, some new data was acked too. */
+ tcp_update_seqack_wnd(c, conn, false, NULL);
+
+ /* initialize headers */
+ hdrlen = tcp_vu_hdrlen(v6);
+ iov_used = 0;
+ num_buffers = 0;
+ check = NULL;
+ frame_size = 0;
+
+ /* iov_vu is an array of buffers and the buffer size can be
+ * smaller than the frame size we want to use but with
+ * num_buffer we can merge several virtio iov buffers in one packet
+ * we need only to set the packet headers in the first iov and
+ * num_buffer to the number of iov entries
+ */
+ for (i = 0; i < iov_cnt && len; i++) {
+
+ if (frame_size == 0)
+ first = &iov_vu[i + 1];
+
+ if (iov_vu[i + 1].iov_len > (size_t)len)
+ iov_vu[i + 1].iov_len = len;
+
+ len -= iov_vu[i + 1].iov_len;
+ iov_used++;
+
+ frame_size += iov_vu[i + 1].iov_len;
+ num_buffers++;
+
+ if (frame_size >= mss || len == 0 ||
+ i + 1 == iov_cnt || !vu_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF)) {
+ if (i + 1 == iov_cnt)
+ check = NULL;
+
+ /* restore first iovec base: point to vnet header */
+ first->iov_base = (char *)first->iov_base - hdrlen;
+ first->iov_len += hdrlen;
+ vu_set_vnethdr(vdev, first->iov_base, num_buffers);
+
+ tcp_vu_prepare(c, conn, first, frame_size, &check);
+ if (*c->pcap) {
+ tcp_vu_update_check(tapside, first, num_buffers);
+ pcap_iov(first, num_buffers,
+ sizeof(struct virtio_net_hdr_mrg_rxbuf));
+ }
+
+ conn->seq_to_tap += frame_size;
+
+ frame_size = 0;
+ num_buffers = 0;
+ }
+ }
+
+ /* release unused buffers */
+ vu_queue_rewind(vq, iov_cnt - iov_used);
+
+ /* send packets */
+ vu_flush(vdev, vq, elem, iov_used);
+
+ conn_flag(c, conn, ACK_FROM_TAP_DUE);
+
+ return 0;
+}
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