From 854ee02b22220377f3fa3806adf7e0718c3a5c5a Mon Sep 17 00:00:00 2001 From: Laurent Vivier Date: Wed, 9 Jul 2025 10:24:24 +0200 Subject: net: Add passt network backend This commit introduces support for passt as a new network backend. passt is an unprivileged, user-mode networking solution that provides connectivity for virtual machines by launching an external helper process. The implementation reuses the generic stream data handling logic. It launches the passt binary using GSubprocess, passing it a file descriptor from a socketpair() for communication. QEMU connects to the other end of the socket pair to establish the network data stream. The PID of the passt daemon is tracked via a temporary file to ensure it is terminated when QEMU exits. Signed-off-by: Laurent Vivier Signed-off-by: Jason Wang --- net/passt.c | 407 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 407 insertions(+) create mode 100644 net/passt.c (limited to 'net/passt.c') diff --git a/net/passt.c b/net/passt.c new file mode 100644 index 0000000000..0a4a1ba6aa --- /dev/null +++ b/net/passt.c @@ -0,0 +1,407 @@ +/* + * passt network backend + * + * Copyright Red Hat + * + * SPDX-License-Identifier: GPL-2.0-or-later + */ +#include "qemu/osdep.h" +#include +#include +#include "net/net.h" +#include "clients.h" +#include "qapi/error.h" +#include "io/net-listener.h" +#include "stream_data.h" + +typedef struct NetPasstState { + NetStreamData data; + GPtrArray *args; + gchar *pidfile; + pid_t pid; +} NetPasstState; + +static int net_passt_stream_start(NetPasstState *s, Error **errp); + +static void net_passt_cleanup(NetClientState *nc) +{ + NetPasstState *s = DO_UPCAST(NetPasstState, data.nc, nc); + + kill(s->pid, SIGTERM); + g_remove(s->pidfile); + g_free(s->pidfile); + g_ptr_array_free(s->args, TRUE); +} + +static ssize_t net_passt_receive(NetClientState *nc, const uint8_t *buf, + size_t size) +{ + NetStreamData *d = DO_UPCAST(NetStreamData, nc, nc); + + return net_stream_data_receive(d, buf, size); +} + +static gboolean net_passt_send(QIOChannel *ioc, GIOCondition condition, + gpointer data) +{ + if (net_stream_data_send(ioc, condition, data) == G_SOURCE_REMOVE) { + NetPasstState *s = DO_UPCAST(NetPasstState, data, data); + Error *error; + + /* we need to restart passt */ + kill(s->pid, SIGTERM); + if (net_passt_stream_start(s, &error) == -1) { + error_report_err(error); + } + + return G_SOURCE_REMOVE; + } + + return G_SOURCE_CONTINUE; +} + +static NetClientInfo net_passt_info = { + .type = NET_CLIENT_DRIVER_PASST, + .size = sizeof(NetPasstState), + .receive = net_passt_receive, + .cleanup = net_passt_cleanup, +}; + +static void net_passt_client_connected(QIOTask *task, gpointer opaque) +{ + NetPasstState *s = opaque; + + if (net_stream_data_client_connected(task, &s->data) == 0) { + qemu_set_info_str(&s->data.nc, "stream,connected to pid %d", s->pid); + } +} + +static int net_passt_start_daemon(NetPasstState *s, int sock, Error **errp) +{ + g_autoptr(GSubprocess) daemon = NULL; + g_autofree gchar *contents = NULL; + g_autoptr(GError) error = NULL; + GSubprocessLauncher *launcher; + + qemu_set_info_str(&s->data.nc, "launching passt"); + + launcher = g_subprocess_launcher_new(G_SUBPROCESS_FLAGS_NONE); + g_subprocess_launcher_take_fd(launcher, sock, 3); + + daemon = g_subprocess_launcher_spawnv(launcher, + (const gchar *const *)s->args->pdata, + &error); + g_object_unref(launcher); + + if (!daemon) { + error_setg(errp, "Error creating daemon: %s", error->message); + return -1; + } + + if (!g_subprocess_wait(daemon, NULL, &error)) { + error_setg(errp, "Error waiting for daemon: %s", error->message); + return -1; + } + + if (g_subprocess_get_if_exited(daemon) && + g_subprocess_get_exit_status(daemon)) { + return -1; + } + + if (!g_file_get_contents(s->pidfile, &contents, NULL, &error)) { + error_setg(errp, "Cannot read passt pid: %s", error->message); + return -1; + } + + s->pid = (pid_t)g_ascii_strtoll(contents, NULL, 10); + if (s->pid <= 0) { + error_setg(errp, "File '%s' did not contain a valid PID.", s->pidfile); + return -1; + } + + return 0; +} + +static int net_passt_stream_start(NetPasstState *s, Error **errp) +{ + QIOChannelSocket *sioc; + SocketAddress *addr; + int sv[2]; + + if (socketpair(PF_UNIX, SOCK_STREAM, 0, sv) == -1) { + error_setg_errno(errp, errno, "socketpair() failed"); + return -1; + } + + /* connect to passt */ + qemu_set_info_str(&s->data.nc, "connecting to passt"); + + /* create socket channel */ + sioc = qio_channel_socket_new(); + s->data.ioc = QIO_CHANNEL(sioc); + s->data.nc.link_down = true; + s->data.send = net_passt_send; + + addr = g_new0(SocketAddress, 1); + addr->type = SOCKET_ADDRESS_TYPE_FD; + addr->u.fd.str = g_strdup_printf("%d", sv[0]); + + qio_channel_socket_connect_async(sioc, addr, + net_passt_client_connected, s, + NULL, NULL); + + qapi_free_SocketAddress(addr); + + /* start passt */ + if (net_passt_start_daemon(s, sv[1], errp) == -1) { + close(sv[0]); + close(sv[1]); + return -1; + } + close(sv[1]); + + return 0; +} + +static GPtrArray *net_passt_decode_args(const NetDevPasstOptions *passt, + gchar *pidfile, Error **errp) +{ + GPtrArray *args = g_ptr_array_new_with_free_func(g_free); + + if (passt->path) { + g_ptr_array_add(args, g_strdup(passt->path)); + } else { + g_ptr_array_add(args, g_strdup("passt")); + } + + /* by default, be quiet */ + if (!passt->has_quiet || passt->quiet) { + g_ptr_array_add(args, g_strdup("--quiet")); + } + + if (passt->has_mtu) { + g_ptr_array_add(args, g_strdup("--mtu")); + g_ptr_array_add(args, g_strdup_printf("%"PRId64, passt->mtu)); + } + + if (passt->address) { + g_ptr_array_add(args, g_strdup("--address")); + g_ptr_array_add(args, g_strdup(passt->address)); + } + + if (passt->netmask) { + g_ptr_array_add(args, g_strdup("--netmask")); + g_ptr_array_add(args, g_strdup(passt->netmask)); + } + + if (passt->mac) { + g_ptr_array_add(args, g_strdup("--mac-addr")); + g_ptr_array_add(args, g_strdup(passt->mac)); + } + + if (passt->gateway) { + g_ptr_array_add(args, g_strdup("--gateway")); + g_ptr_array_add(args, g_strdup(passt->gateway)); + } + + if (passt->interface) { + g_ptr_array_add(args, g_strdup("--interface")); + g_ptr_array_add(args, g_strdup(passt->interface)); + } + + if (passt->outbound) { + g_ptr_array_add(args, g_strdup("--outbound")); + g_ptr_array_add(args, g_strdup(passt->outbound)); + } + + if (passt->outbound_if4) { + g_ptr_array_add(args, g_strdup("--outbound-if4")); + g_ptr_array_add(args, g_strdup(passt->outbound_if4)); + } + + if (passt->outbound_if6) { + g_ptr_array_add(args, g_strdup("--outbound-if6")); + g_ptr_array_add(args, g_strdup(passt->outbound_if6)); + } + + if (passt->dns) { + g_ptr_array_add(args, g_strdup("--dns")); + g_ptr_array_add(args, g_strdup(passt->dns)); + } + if (passt->fqdn) { + g_ptr_array_add(args, g_strdup("--fqdn")); + g_ptr_array_add(args, g_strdup(passt->fqdn)); + } + + if (passt->has_dhcp_dns && !passt->dhcp_dns) { + g_ptr_array_add(args, g_strdup("--no-dhcp-dns")); + } + + if (passt->has_dhcp_search && !passt->dhcp_search) { + g_ptr_array_add(args, g_strdup("--no-dhcp-search")); + } + + if (passt->map_host_loopback) { + g_ptr_array_add(args, g_strdup("--map-host-loopback")); + g_ptr_array_add(args, g_strdup(passt->map_host_loopback)); + } + + if (passt->map_guest_addr) { + g_ptr_array_add(args, g_strdup("--map-guest-addr")); + g_ptr_array_add(args, g_strdup(passt->map_guest_addr)); + } + + if (passt->dns_forward) { + g_ptr_array_add(args, g_strdup("--dns-forward")); + g_ptr_array_add(args, g_strdup(passt->dns_forward)); + } + + if (passt->dns_host) { + g_ptr_array_add(args, g_strdup("--dns-host")); + g_ptr_array_add(args, g_strdup(passt->dns_host)); + } + + if (passt->has_tcp && !passt->tcp) { + g_ptr_array_add(args, g_strdup("--no-tcp")); + } + + if (passt->has_udp && !passt->udp) { + g_ptr_array_add(args, g_strdup("--no-udp")); + } + + if (passt->has_icmp && !passt->icmp) { + g_ptr_array_add(args, g_strdup("--no-icmp")); + } + + if (passt->has_dhcp && !passt->dhcp) { + g_ptr_array_add(args, g_strdup("--no-dhcp")); + } + + if (passt->has_ndp && !passt->ndp) { + g_ptr_array_add(args, g_strdup("--no-ndp")); + } + if (passt->has_dhcpv6 && !passt->dhcpv6) { + g_ptr_array_add(args, g_strdup("--no-dhcpv6")); + } + + if (passt->has_ra && !passt->ra) { + g_ptr_array_add(args, g_strdup("--no-ra")); + } + + if (passt->has_freebind && passt->freebind) { + g_ptr_array_add(args, g_strdup("--freebind")); + } + + if (passt->has_ipv4 && !passt->ipv4) { + g_ptr_array_add(args, g_strdup("--ipv6-only")); + } + + if (passt->has_ipv6 && !passt->ipv6) { + g_ptr_array_add(args, g_strdup("--ipv4-only")); + } + + if (passt->has_search && passt->search) { + const StringList *list = passt->search; + GString *domains = g_string_new(list->value->str); + + list = list->next; + while (list) { + g_string_append(domains, " "); + g_string_append(domains, list->value->str); + list = list->next; + } + + g_ptr_array_add(args, g_strdup("--search")); + g_ptr_array_add(args, g_string_free(domains, FALSE)); + } + + if (passt->has_tcp_ports && passt->tcp_ports) { + const StringList *list = passt->tcp_ports; + GString *tcp_ports = g_string_new(list->value->str); + + list = list->next; + while (list) { + g_string_append(tcp_ports, ","); + g_string_append(tcp_ports, list->value->str); + list = list->next; + } + + g_ptr_array_add(args, g_strdup("--tcp-ports")); + g_ptr_array_add(args, g_string_free(tcp_ports, FALSE)); + } + + if (passt->has_udp_ports && passt->udp_ports) { + const StringList *list = passt->udp_ports; + GString *udp_ports = g_string_new(list->value->str); + + list = list->next; + while (list) { + g_string_append(udp_ports, ","); + g_string_append(udp_ports, list->value->str); + list = list->next; + } + + g_ptr_array_add(args, g_strdup("--udp-ports")); + g_ptr_array_add(args, g_string_free(udp_ports, FALSE)); + } + + if (passt->has_param && passt->param) { + const StringList *list = passt->param; + + while (list) { + g_ptr_array_add(args, g_strdup(list->value->str)); + list = list->next; + } + } + + /* provide a pid file to be able to kil passt on exit */ + g_ptr_array_add(args, g_strdup("--pid")); + g_ptr_array_add(args, g_strdup(pidfile)); + + /* g_subprocess_launcher_take_fd() will set the socket on fd 3 */ + g_ptr_array_add(args, g_strdup("--fd")); + g_ptr_array_add(args, g_strdup("3")); + + g_ptr_array_add(args, NULL); + + return args; +} + +int net_init_passt(const Netdev *netdev, const char *name, + NetClientState *peer, Error **errp) +{ + g_autoptr(GError) error = NULL; + NetClientState *nc; + NetPasstState *s; + GPtrArray *args; + gchar *pidfile; + int pidfd; + + assert(netdev->type == NET_CLIENT_DRIVER_PASST); + + pidfd = g_file_open_tmp("passt-XXXXXX.pid", &pidfile, &error); + if (pidfd == -1) { + error_setg(errp, "Failed to create temporary file: %s", error->message); + return -1; + } + close(pidfd); + + args = net_passt_decode_args(&netdev->u.passt, pidfile, errp); + if (args == NULL) { + g_free(pidfile); + return -1; + } + + nc = qemu_new_net_client(&net_passt_info, peer, "passt", name); + s = DO_UPCAST(NetPasstState, data.nc, nc); + + s->args = args; + s->pidfile = pidfile; + + if (net_passt_stream_start(s, errp) == -1) { + qemu_del_net_client(nc); + return -1; + } + + return 0; +} -- cgit 1.4.1