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passt/qrap.c
Stefano Brivio 9af2e5d5fc qrap: Add a neighbour solicitation to probe frames, instead of just ARP
For a while now, passt disables ARP functionality completely if IPv4
is disabled. If qrap sends an ARP request as a probe in that case, it
will receive no answer and move on, trying to find another instance.

Add a second probe frame, a hardcoded neighbour solicitation, so that
we get a neighbour advertisement if IPv6 is enabled.

Without this change, IPv6-only operation is completely broken.

Reported-by: Wenli Quan <wquan@redhat.com>
Reported-by: Alona Paz <alkaplan@redhat.com>
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2106257
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2022-07-20 18:19:57 +02:00

370 lines
8.6 KiB
C

// SPDX-License-Identifier: AGPL-3.0-or-later
/* PASST - Plug A Simple Socket Transport
*
* qrap.c - qemu wrapper connecting UNIX domain socket to file descriptor
*
* Copyright (c) 2020-2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*
* TODO: Implement this functionality directly in qemu: we have TCP and UDP
* socket back-ends already.
*/
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <linux/limits.h>
#include <limits.h>
#include <fcntl.h>
#include <net/if_arp.h>
#include <netinet/in.h>
#include <netinet/ip6.h>
#include <netinet/if_ether.h>
#include <time.h>
#include <linux/icmpv6.h>
#include "util.h"
#include "passt.h"
#include "arp.h"
static char *qemu_names[] = {
"kvm",
"qemu-kvm",
#ifdef ARCH
( "qemu-system-" ARCH ),
#endif
"/usr/libexec/qemu-kvm",
NULL,
};
/**
* struct drop_arg - Drop matching arguments on command line
* @name: Option name
* @val: Substring in option value, NULL matches any value
*/
static const struct drop_arg {
char *name;
char *val;
} drop_args[] = {
{ "-netdev", NULL },
{ "-net", NULL },
{ "-device", "virtio-net-pci," },
{ "-device", "virtio-net-ccw," },
{ "-device", "e1000," },
{ "-device", "e1000e," },
{ "-device", "rtl8139," },
{ 0 },
};
/**
* struct pci_dev - PCI devices to add on command line depending on machine name
* @mach: Machine name
* @name: Device ("-device") name to insert
* @template: Prefix for device specification (first part of address)
* @template_post: Suffix for device specification (last part of address)
* @first: First usable PCI address
* @last: Last usable PCI address
*/
static const struct pci_dev {
char *mach;
char *name;
char *template;
char *template_post;
int first;
int last;
} pci_devs[] = {
{ "pc-q35", "virtio-net-pci",
"bus=pci.", ",addr=0x0", 3, /* 2: hotplug bus */ 16 },
{ "pc-", "virtio-net-pci",
"bus=pci.0,addr=0x", "", 2, /* 1: ISA bridge */ 16 },
{ "s390-ccw", "virtio-net-ccw",
"devno=fe.0.", "", 1, 16 },
{ 0 },
};
#define DEFAULT_FD 5
/**
* usage() - Print usage and exit
* @name: Executable name
*/
void usage(const char *name)
{
fprintf(stderr, "Usage: %s [FDNUM QEMU_CMD] [QEMU_ARG]...\n", name);
fprintf(stderr, "\n");
fprintf(stderr, "If first and second arguments aren't a socket number\n"
"and a path, %s will try to locate a qemu binary\n"
"and directly patch the command line\n", name);
exit(EXIT_FAILURE);
}
/**
* main() - Entry point and main loop
* @argc: Argument count
* @argv: File descriptor number, then qemu with arguments
*
* Return: 0 once interrupted, non-zero on failure
*/
int main(int argc, char **argv)
{
int i, s, qemu_argc = 0, addr_map = 0, has_dev = 0, retry_on_reset, err;
struct timeval tv = { .tv_sec = 0, .tv_usec = (long)(500 * 1000) };
char *qemu_argv[ARG_MAX], dev_str[ARG_MAX];
struct sockaddr_un addr = {
.sun_family = AF_UNIX,
};
const struct pci_dev *dev = NULL;
long fd;
struct {
uint32_t vnet_len4;
struct ethhdr eh4;
struct arphdr ah;
struct arpmsg am;
uint32_t vnet_len6;
struct ethhdr eh6;
struct ipv6hdr ip6hr;
struct icmp6hdr ihr;
struct in6_addr target;
} __attribute__((__packed__)) probe = {
.vnet_len4 = htonl(42),
{
.h_dest = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff },
.h_source = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff },
.h_proto = htons(ETH_P_ARP),
},
{ .ar_hrd = htons(ARPHRD_ETHER),
.ar_pro = htons(ETH_P_IP),
.ar_hln = ETH_ALEN,
.ar_pln = 4,
.ar_op = htons(ARPOP_REQUEST),
},
{
.sha = { 0 }, .sip = { 0 }, .tha = { 0 }, .tip = { 0 },
},
.vnet_len6 = htonl(78),
{
.h_dest = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff },
.h_source = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff },
.h_proto = htons(ETH_P_IPV6),
},
{
.version = 6,
.payload_len = htons(24),
.nexthdr = IPPROTO_ICMPV6,
.hop_limit = 255,
.saddr = IN6ADDR_LOOPBACK_INIT,
.daddr = IN6ADDR_ANY_INIT,
},
{
.icmp6_type = 135,
.icmp6_code = 0,
},
IN6ADDR_ANY_INIT,
};
char probe_r;
if (argc >= 3) {
errno = 0;
fd = strtol(argv[1], NULL, 0);
if (fd >= 3 && fd < INT_MAX && !errno) {
char env_path[ARG_MAX + 1], *p, command[ARG_MAX];
strncpy(env_path, getenv("PATH"), ARG_MAX);
p = strtok(env_path, ":");
while (p) {
snprintf(command, ARG_MAX, "%s/%s", p, argv[2]);
if (!access(command, X_OK))
goto valid_args;
p = strtok(NULL, ":");
}
}
}
fd = DEFAULT_FD;
for (i = 1; i < argc - 1; i++) {
if (strcmp(argv[i], "-machine"))
continue;
for (dev = pci_devs; dev->mach; dev++) {
if (strstr(argv[i + 1], dev->mach) == argv[i + 1])
break;
}
}
if (!dev || !dev->mach)
dev = pci_devs;
for (qemu_argc = 1, i = 1; i < argc; i++) {
const struct drop_arg *a;
for (a = drop_args; a->name; a++) {
if (!strcmp(argv[i], a->name)) {
if (!a->val)
break;
if (i + 1 < argc &&
strstr(argv[i + 1], a->val) == argv[i + 1])
break;
}
}
if (a->name) {
i++;
continue;
}
if (!strcmp(argv[i], "-device") && i + 1 < argc) {
char *p;
has_dev = 1;
if ((p = strstr(argv[i + 1], dev->template))) {
long n;
n = strtol(p + strlen(dev->template), NULL, 16);
if (!errno)
addr_map |= (1 << n);
}
}
qemu_argv[qemu_argc++] = argv[i];
}
for (i = dev->first; i < dev->last; i++) {
if (!(addr_map & (1 << i)))
break;
}
if (i == dev->last) {
fprintf(stderr, "Couldn't find free address for device\n");
usage(argv[0]);
}
if (has_dev) {
qemu_argv[qemu_argc++] = "-device";
snprintf(dev_str, ARG_MAX, "%s,%s%x%s,netdev=hostnet0,x-txburst=4096",
dev->name, dev->template, i, dev->template_post);
qemu_argv[qemu_argc++] = dev_str;
}
qemu_argv[qemu_argc++] = "-netdev";
qemu_argv[qemu_argc++] = "socket,fd=" STR(DEFAULT_FD) ",id=hostnet0";
qemu_argv[qemu_argc] = NULL;
valid_args:
for (i = 1; i < UNIX_SOCK_MAX; i++) {
retry_on_reset = 50;
retry:
s = socket(AF_UNIX, SOCK_STREAM, 0);
if (s < 0) {
perror("socket");
exit(EXIT_FAILURE);
}
if (setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)))
perror("setsockopt SO_RCVTIMEO");
if (setsockopt(s, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv)))
perror("setsockopt SO_SNDTIMEO");
snprintf(addr.sun_path, UNIX_PATH_MAX, UNIX_SOCK_PATH, i);
errno = 0;
if (connect(s, (const struct sockaddr *)&addr, sizeof(addr))) {
err = errno;
perror("connect");
} else if (send(s, &probe, sizeof(probe), 0) != sizeof(probe)) {
err = errno;
perror("send");
} else if (recv(s, &probe_r, 1, MSG_PEEK) <= 0) {
err = errno;
perror("recv");
} else {
break;
}
/* FIXME: in a KubeVirt environment, libvirtd invokes qrap three
* times in a strict sequence when a virtual machine needs to
* be started, namely, when:
* - the domain XML is saved
* - the domain is started (for "probing")
* - the virtual machine is started for real
* and it often happens that the qemu process is still running
* when qrap is invoked again, so passt will refuse the new
* connection because the previous one is still active. This
* overlap seems to be anywhere between 0 and 3ms.
*
* If we get a connection reset, retry a few times, to allow for
* the previous qemu instance to terminate and, in turn, for the
* connection to passt to be closed.
*
* This should be fixed in libvirt instead. It probably makes
* sense to check this behaviour once native libvirt support is
* there, and this implies native qemu support too, so at that
* point qrap will have no reason to exist anymore -- that is,
* this FIXME will probably remain until the tool itself is
* obsoleted.
*/
if (retry_on_reset && err == ECONNRESET) {
retry_on_reset--;
usleep(50 * 1000);
goto retry;
}
fprintf(stderr, "Probe of %s failed\n", addr.sun_path);
close(s);
}
if (i == UNIX_SOCK_MAX) {
perror("connect");
exit(EXIT_FAILURE);
}
tv.tv_usec = 0;
if (setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)))
perror("setsockopt, SO_RCVTIMEO reset");
if (setsockopt(s, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv)))
perror("setsockopt, SO_SNDTIMEO reset");
fprintf(stderr, "Connected to %s\n", addr.sun_path);
if (dup2(s, (int)fd) < 0) {
perror("dup");
exit(EXIT_FAILURE);
}
close(s);
if (qemu_argc) {
char **name;
for (name = qemu_names; *name; name++) {
qemu_argv[0] = *name;
execvp(*name, qemu_argv);
if (errno != ENOENT) {
perror("execvp");
usage(argv[0]);
}
}
if (errno == ENOENT)
fprintf(stderr, "Couldn't find qemu command\n");
} else {
execvp(argv[2], argv + 2);
}
perror("execvp");
return EXIT_FAILURE;
}