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| | // 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"
#include <time.h>
static struct iovec iov_vu[VIRTQUEUE_MAX_SIZE + 1];
static struct vu_virtq_element elem[VIRTQUEUE_MAX_SIZE];
/**
* tcp_vu_l2_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_l2_hdrlen(bool v6)
{
size_t l2_hdrlen;
l2_hdrlen = sizeof(struct ethhdr) + sizeof(struct tcphdr);
if (v6)
l2_hdrlen += sizeof(struct ipv6hdr);
else
l2_hdrlen += sizeof(struct iphdr);
return l2_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;
struct tcphdr *th;
uint32_t psum;
if (inany_v4(&tapside->oaddr)) {
const struct in_addr *src4 = inany_v4(&tapside->oaddr);
const struct in_addr *dst4 = inany_v4(&tapside->eaddr);
const struct iphdr *iph = vu_ip(base);
size_t l4len = ntohs(iph->tot_len) - sizeof(*th);
th = vu_payloadv4(base);
psum = proto_ipv4_header_psum(l4len, IPPROTO_TCP, *src4, *dst4);
} else {
const struct ipv6hdr *ip6h = vu_ip(base);
size_t l4len = ntohs(ip6h->payload_len);
th = vu_payloadv6(base);
psum = proto_ipv6_header_psum(l4len, IPPROTO_TCP,
&ip6h->saddr, &ip6h->daddr);
}
tcp_update_csum(psum, th, iov, iov_used, (char *)(th + 1) - 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, optlen, hdrlen;
struct ipv6hdr *ip6h = NULL;
struct tcp_syn_opts *opts;
struct iphdr *iph = NULL;
struct tcphdr *th;
struct ethhdr *eh;
uint32_t seq;
int elem_cnt;
int nb_ack;
int ret;
hdrlen = tcp_vu_l2_hdrlen(CONN_V6(conn));
vu_init_elem(elem, iov_vu, 2);
elem_cnt = vu_collect_one_frame(vdev, vq, elem, 1,
hdrlen + sizeof(struct tcp_syn_opts),
0, NULL);
if (elem_cnt < 1)
return 0;
vu_set_vnethdr(vdev, &iov_vu[0], 1, 0);
eh = vu_eth(iov_vu[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)) {
eh->h_proto = htons(ETH_P_IP);
iph = vu_ip(iov_vu[0].iov_base);
*iph = (struct iphdr)L2_BUF_IP4_INIT(IPPROTO_TCP);
th = vu_payloadv4(iov_vu[0].iov_base);
} else {
eh->h_proto = htons(ETH_P_IPV6);
ip6h = vu_ip(iov_vu[0].iov_base);
*ip6h = (struct ipv6hdr)L2_BUF_IP6_INIT(IPPROTO_TCP);
th = vu_payloadv6(iov_vu[0].iov_base);
}
memset(th, 0, sizeof(*th));
th->doff = offsetof(struct tcp_flags_t, opts) / 4;
th->ack = 1;
seq = conn->seq_to_tap;
opts = (struct tcp_syn_opts *)(th + 1);
ret = tcp_prepare_flags(c, conn, flags, th, opts, &optlen);
if (ret <= 0) {
vu_queue_rewind(vq, 1);
return ret;
}
l2len = hdrlen + optlen;
elem[0].in_sg[0].iov_len = l2len +
sizeof(struct virtio_net_hdr_mrg_rxbuf);
if (CONN_V4(conn)) {
tcp_fill_headers4(conn, NULL, iph, th, iov_vu, 1,
(char *)opts - (char *)iov_vu[0].iov_base,
NULL, seq, true);
} else {
tcp_fill_headers6(conn, NULL, ip6h, th, iov_vu, 1,
(char *)opts - (char *)iov_vu[0].iov_base,
seq, true);
}
if (*c->pcap) {
tcp_vu_update_check(tapside, &elem[0].in_sg[0], 1);
pcap_iov(&elem[0].in_sg[0], 1,
sizeof(struct virtio_net_hdr_mrg_rxbuf));
}
nb_ack = 1;
if (flags & DUP_ACK) {
elem_cnt = vu_collect_one_frame(vdev, vq, &elem[1], 1, l2len,
0, NULL);
if (elem_cnt == 1) {
memcpy(elem[1].in_sg[0].iov_base,
elem[0].in_sg[0].iov_base, l2len);
vu_set_vnethdr(vdev, &elem[1].in_sg[0], 1, 0);
nb_ack++;
if (*c->pcap)
pcap_iov(&elem[1].in_sg[0], 1, 0);
}
}
vu_flush(vdev, vq, 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
* @fillsize: Number of bytes we can receive
* @dlen: Size of received data (output)
*
* Return: Number of iov entries used to store the data
*/
static ssize_t tcp_vu_sock_recv(const struct ctx *c,
struct tcp_tap_conn *conn, bool v6,
size_t fillsize, ssize_t *dlen)
{
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 l2_hdrlen;
int elem_cnt;
ssize_t ret;
*dlen = 0;
l2_hdrlen = tcp_vu_l2_hdrlen(v6);
vu_init_elem(elem, &iov_vu[1], VIRTQUEUE_MAX_SIZE);
elem_cnt = vu_collect(vdev, vq, elem, VIRTQUEUE_MAX_SIZE, mss,
l2_hdrlen, fillsize);
if (elem_cnt < 0) {
tcp_rst(c, conn);
return -ENOMEM;
}
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);
if (ret < 0) {
vu_queue_rewind(vq, elem_cnt);
if (errno != EAGAIN && errno != EWOULDBLOCK) {
ret = -errno;
tcp_rst(c, conn);
}
return ret;
}
if (!ret) {
vu_queue_rewind(vq, elem_cnt);
if ((conn->events & (SOCK_FIN_RCVD | TAP_FIN_SENT)) == SOCK_FIN_RCVD) {
int retf = tcp_vu_send_flag(c, conn, FIN | ACK);
if (retf) {
tcp_rst(c, conn);
return retf;
}
conn_event(c, conn, TAP_FIN_SENT);
}
return 0;
}
*dlen = ret;
return elem_cnt;
}
/**
* tcp_vu_prepare() - Prepare the packet header
* @c: Execution context
* @conn: Connection pointer
* @iov: Pointer to the array of IO vectors
* @iov_cnt: Number of entries in @iov
* @check: Checksum, if already known
*/
static void tcp_vu_prepare(const struct ctx *c, struct tcp_tap_conn *conn,
struct iovec *iov, size_t iov_cnt,
const uint16_t **check)
{
const struct flowside *toside = TAPFLOW(conn);
char *base = iov[0].iov_base;
struct ipv6hdr *ip6h = NULL;
struct iphdr *iph = NULL;
struct tcphdr *th;
struct ethhdr *eh;
char *data;
/* 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)) {
ASSERT(iov[0].iov_len >= sizeof(struct virtio_net_hdr_mrg_rxbuf) +
sizeof(struct ethhdr) + sizeof(struct iphdr) +
sizeof(struct tcphdr));
eh->h_proto = htons(ETH_P_IP);
iph = vu_ip(base);
*iph = (struct iphdr)L2_BUF_IP4_INIT(IPPROTO_TCP);
th = vu_payloadv4(base);
} else {
ASSERT(iov[0].iov_len >= sizeof(struct virtio_net_hdr_mrg_rxbuf) +
sizeof(struct ethhdr) + sizeof(struct ipv6hdr) +
sizeof(struct tcphdr));
eh->h_proto = htons(ETH_P_IPV6);
ip6h = vu_ip(base);
*ip6h = (struct ipv6hdr)L2_BUF_IP6_INIT(IPPROTO_TCP);
th = vu_payloadv6(base);
}
memset(th, 0, sizeof(*th));
th->doff = offsetof(struct tcp_payload_t, data) / 4;
th->ack = 1;
data = (char *)(th + 1);
if (inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr)) {
tcp_fill_headers4(conn, NULL, iph, th, iov, iov_cnt, data - base,
*check, conn->seq_to_tap, true);
*check = &iph->check;
} else {
tcp_fill_headers6(conn, NULL, ip6h, th, iov, iov_cnt, data - base,
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 l2_hdrlen, fillsize;
int i, iov_cnt, iov_used;
uint32_t already_sent = 0;
int v6 = CONN_V6(conn);
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 (!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;
if (peek_offset_cap)
already_sent = 0;
iov_vu[0].iov_base = tcp_buf_discard;
iov_vu[0].iov_len = already_sent;
fillsize -= already_sent;
/* collect the buffers from vhost-user and fill them with the
* data from the socket
*/
iov_cnt = tcp_vu_sock_recv(c, conn, v6, fillsize, &len);
if (iov_cnt <= 0)
return iov_cnt;
len -= already_sent;
if (len <= 0) {
conn_flag(c, conn, STALLED);
vu_queue_rewind(vq, iov_cnt);
return 0;
}
conn_flag(c, conn, ~STALLED);
/* Likely, some new data was acked too. */
tcp_update_seqack_wnd(c, conn, 0, NULL);
/* initialize headers */
l2_hdrlen = tcp_vu_l2_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 */
vu_set_vnethdr(vdev, first, num_buffers, l2_hdrlen);
tcp_vu_prepare(c, conn, first, num_buffers, &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;
}
|