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| | // SPDX-License-Identifier: GPL-2.0-or-later
/* udp_vu.c - UDP L2 vhost-user management functions
*
* Copyright Red Hat
* Author: Laurent Vivier <lvivier@redhat.com>
*/
#include <unistd.h>
#include <assert.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/udp.h>
#include <stdint.h>
#include <stddef.h>
#include <sys/uio.h>
#include <linux/virtio_net.h>
#include "checksum.h"
#include "util.h"
#include "ip.h"
#include "siphash.h"
#include "inany.h"
#include "passt.h"
#include "pcap.h"
#include "log.h"
#include "vhost_user.h"
#include "udp_internal.h"
#include "flow.h"
#include "flow_table.h"
#include "udp_flow.h"
#include "udp_vu.h"
#include "vu_common.h"
/**
* udp_vu_hdrlen() - Sum size of all headers, from UDP to virtio-net
* @v6: Set for IPv6 packet
*
* Return: total size of virtio-net, Ethernet, IP, and UDP headers
*/
static size_t udp_vu_hdrlen(bool v6)
{
size_t hdrlen;
hdrlen = VNET_HLEN + sizeof(struct ethhdr) + sizeof(struct udphdr);
if (v6)
hdrlen += sizeof(struct ipv6hdr);
else
hdrlen += sizeof(struct iphdr);
return hdrlen;
}
/**
* udp_vu_sock_recv() - Receive datagrams from socket into vhost-user buffers
* @payload: UDP payload
* @cnt: Number of used entries in @payload to store the datagram (output)
* Unchanged on failure
* @s: Socket to receive from
*
* Return: size of received data, -1 on error
*/
static ssize_t udp_vu_sock_recv(struct iov_tail *payload, size_t *cnt, int s)
{
struct iovec msg_iov[VIRTQUEUE_MAX_SIZE];
struct msghdr msg = { 0 };
size_t iov_used;
ssize_t dlen;
msg.msg_iov = msg_iov;
msg.msg_iovlen = iov_tail_clone(msg.msg_iov, ARRAY_SIZE(msg_iov),
payload);
/* read data from the socket */
dlen = recvmsg(s, &msg, 0);
if (dlen < 0)
return -1;
iov_used = iov_skip_bytes(payload->iov, payload->cnt,
MAX(dlen + payload->off,
VNET_HLEN + ETH_ZLEN), NULL);
if (iov_used < payload->cnt)
iov_used++;
*cnt = iov_used; /* one iovec per element */
return dlen;
}
/**
* udp_vu_prepare() - Prepare the packet header
* @c: Execution context
* @data: IO vector tail for the L2 frame, on return points to the L4 header
* @payload: UDP payload
* @toside: Address information for one side of the flow
* @dlen: Packet data length
*/
static void udp_vu_prepare(const struct ctx *c, struct iov_tail *data,
struct iov_tail *payload,
const struct flowside *toside, size_t dlen)
{
bool ipv4 = inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr);
struct ethhdr eh;
struct udphdr uh;
/* ethernet header */
memcpy(eh.h_dest, c->guest_mac, sizeof(eh.h_dest));
memcpy(eh.h_source, c->our_tap_mac, sizeof(eh.h_source));
if (ipv4)
eh.h_proto = htons(ETH_P_IP);
else
eh.h_proto = htons(ETH_P_IPV6);
IOV_PUSH_HEADER(data, eh);
/* initialize header */
if (ipv4) {
struct iphdr iph = (struct iphdr)L2_BUF_IP4_INIT(IPPROTO_UDP);
udp_update_hdr4(&iph, &uh, payload, toside, dlen, !*c->pcap);
IOV_PUSH_HEADER(data, iph);
} else {
struct ipv6hdr ip6h = (struct ipv6hdr)L2_BUF_IP6_INIT(IPPROTO_UDP);
udp_update_hdr6(&ip6h, &uh, payload, toside, dlen, !*c->pcap);
IOV_PUSH_HEADER(data, ip6h);
}
IOV_PUSH_HEADER(data, uh);
}
/**
* udp_vu_sock_to_tap() - Forward datagrams from socket to tap
* @c: Execution context
* @s: Socket to read data from
* @n: Maximum number of datagrams to forward
* @tosidx: Flow & side to forward data from @s to
*/
void udp_vu_sock_to_tap(const struct ctx *c, int s, int n, flow_sidx_t tosidx)
{
const struct flowside *toside = flowside_at_sidx(tosidx);
bool v6 = !(inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr));
static struct vu_virtq_element elem[VIRTQUEUE_MAX_SIZE];
static struct iovec iov_vu[VIRTQUEUE_MAX_SIZE];
struct vu_dev *vdev = c->vdev;
struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
size_t hdrlen = udp_vu_hdrlen(v6);
int i;
assert(!c->no_udp);
if (!vu_queue_enabled(vq) || !vu_queue_started(vq)) {
struct msghdr msg = { 0 };
debug("Got UDP packet, but RX virtqueue not usable yet");
for (i = 0; i < n; i++) {
if (recvmsg(s, &msg, MSG_DONTWAIT) < 0)
debug_perror("Failed to discard datagram");
}
return;
}
for (i = 0; i < n; i++) {
unsigned elem_cnt, elem_used, j, k;
struct iov_tail payload;
size_t iov_cnt;
ssize_t dlen;
elem_cnt = vu_collect(vdev, vq, elem, ARRAY_SIZE(elem),
iov_vu, ARRAY_SIZE(iov_vu), &iov_cnt,
IP_MAX_MTU + ETH_HLEN + VNET_HLEN, NULL);
if (elem_cnt == 0)
break;
payload = IOV_TAIL(iov_vu, iov_cnt, hdrlen);
dlen = udp_vu_sock_recv(&payload, &iov_cnt, s);
if (dlen < 0) {
vu_queue_rewind(vq, elem_cnt);
break;
}
elem_used = 0;
for (j = 0, k = 0; k < iov_cnt && j < elem_cnt; j++) {
size_t iov_still_needed = iov_cnt - k;
if (elem[j].in_num > iov_still_needed)
elem[j].in_num = iov_still_needed;
k += elem[j].in_num;
elem_used++;
}
/* release unused buffers */
vu_queue_rewind(vq, elem_cnt - elem_used);
if (iov_cnt > 0) {
struct iov_tail data = IOV_TAIL(iov_vu, iov_cnt, VNET_HLEN);
udp_vu_prepare(c, &data, &payload, toside, dlen);
if (*c->pcap) {
pcap_iov(iov_vu, iov_cnt, VNET_HLEN,
hdrlen + dlen - VNET_HLEN);
}
vu_pad(iov_vu, iov_cnt, hdrlen + dlen);
vu_flush(vdev, vq, elem, elem_used, hdrlen + dlen);
vu_queue_notify(vdev, vq);
}
}
}
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