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// SPDX-License-Identifier: EUPL-1.2+
// SPDX-FileCopyrightText: 2022 Alyssa Ross <hi@alyssa.is>
#include "ch.h"
#include "net-util.h"
#include <assert.h>
#include <err.h>
#include <errno.h>
#include <net/if.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdnoreturn.h>
#include <string.h>
#include <unistd.h>
#include <sys/un.h>
#include <linux/if_tun.h>
static int setup_tap(const char *bridge_name, const char *tap_prefix)
{
int fd;
char tap_name[IFNAMSIZ];
// We assume ≤16-bit pids.
if (snprintf(tap_name, sizeof tap_name, "%s%d",
tap_prefix, getpid()) == -1)
return -1;
if ((fd = tap_open(tap_name, IFF_NO_PI|IFF_VNET_HDR|IFF_TUN_EXCL)) == -1)
goto out;
if (bridge_add_if(bridge_name, tap_name) == -1)
goto fail;
if (if_up(tap_name) == -1)
goto fail;
goto out;
fail:
close(fd);
fd = -1;
out:
return fd;
}
static int client_net_setup(const char *bridge_name)
{
return setup_tap(bridge_name, "client");
}
static int router_net_setup(const char *bridge_name, const char *router_vm_name,
const uint8_t mac[6], struct ch_device **out)
{
int e, fd = setup_tap(bridge_name, "router");
if (fd == -1)
return -1;
e = ch_add_net(router_vm_name, fd, mac, out);
close(fd);
if (!e)
return 0;
errno = e;
return -1;
}
static int router_net_cleanup(pid_t pid, const char *vm_name,
struct ch_device *vm_net_device)
{
int e;
char name[IFNAMSIZ], newname[IFNAMSIZ], brname[IFNAMSIZ];
if ((e = ch_remove_device(vm_name, vm_net_device))) {
errno = e;
return -1;
}
// Work around cloud-hypervisor not closing taps it's no
// longer using by freeing up the name.
//
// We assume ≤16-bit pids.
snprintf(name, sizeof name, "router%d", pid);
snprintf(newname, sizeof newname, "_dead%d", pid);
snprintf(brname, sizeof brname, "br%d", pid);
if (bridge_remove_if(brname, name) == -1)
warn("removing %s from %s", name, brname);
if (if_down(name) == -1)
return -1;
return if_rename(name, newname);
}
static int bridge_cleanup(pid_t pid)
{
char name[IFNAMSIZ];
snprintf(name, sizeof name, "br%d", pid);
return bridge_delete(name);
}
static noreturn void exit_listener_main(int fd, pid_t pid,
const char *router_vm_name,
struct ch_device *router_vm_net_device)
{
// Wait for the other end of the pipe to be closed.
int status = EXIT_SUCCESS;
struct pollfd pollfd = { .fd = fd, .events = 0, .revents = 0 };
while (poll(&pollfd, 1, -1) == -1) {
if (errno == EINTR || errno == EWOULDBLOCK)
continue;
err(1, "poll");
}
assert(pollfd.revents == POLLERR);
if (router_net_cleanup(pid, router_vm_name,
router_vm_net_device) == -1) {
warn("cleaning up router tap");
status = EXIT_FAILURE;
}
if (bridge_cleanup(pid) == -1) {
warn("cleaning up bridge");
status = EXIT_FAILURE;
}
exit(status);
}
static int exit_listener_setup(const char *router_vm_name,
struct ch_device *router_vm_net_device)
{
pid_t pid = getpid();
int fd[2];
if (pipe(fd) == -1)
return -1;
switch (fork()) {
case -1:
close(fd[0]);
close(fd[1]);
return -1;
case 0:
close(fd[0]);
exit_listener_main(fd[1], pid, router_vm_name,
router_vm_net_device);
default:
close(fd[1]);
return 0;
}
}
struct net_config {
int fd;
char mac[6];
};
struct net_config net_setup(const char *router_vm_name)
{
struct ch_device *router_vm_net_device = NULL;
struct net_config r = { .fd = -1, .mac = { 0 } };
char bridge_name[IFNAMSIZ];
pid_t pid = getpid();
// We assume ≤16-bit pids.
uint8_t router_mac[6] = { 0x0A, 0xB3, 0xEC, 0x80, pid >> 8, pid };
memcpy(r.mac, router_mac, 6);
r.mac[3] = 0x00;
if (snprintf(bridge_name, sizeof bridge_name, "br%d", pid) == -1)
return r;
if (bridge_add(bridge_name) == -1)
goto out;
if (if_up(bridge_name) == -1)
goto fail_bridge;
if ((r.fd = client_net_setup(bridge_name)) == -1)
goto fail_bridge;
if (router_net_setup(bridge_name, router_vm_name, router_mac,
&router_vm_net_device) == -1)
goto fail_bridge;
// Set up a process that will listen for this process dying,
// and remove the interface from the netvm, and delete the
// bridge.
if (exit_listener_setup(router_vm_name, router_vm_net_device) == -1)
goto fail_bridge;
goto out;
fail_bridge:
bridge_delete(bridge_name);
close(r.fd);
r.fd = -1;
out:
ch_device_free(router_vm_net_device);
return r;
}
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