NetworkManager/src/core/dhcp/nm-dhcp-dhcpcd.c

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Copyright (C) 2008,2020 Roy Marples <roy@marples.name>
 * Copyright (C) 2010 Dan Williams <dcbw@redhat.com>
 */

#include "src/core/nm-default-daemon.h"

#if WITH_DHCPCD

#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "nm-dhcp-manager.h"
#include "nm-utils.h"
#include "NetworkManagerUtils.h"
#include "nm-dhcp-listener.h"
#include "nm-dhcp-client-logging.h"

/*****************************************************************************/

#define NM_TYPE_DHCP_DHCPCD (nm_dhcp_dhcpcd_get_type())
#define NM_DHCP_DHCPCD(obj) (G_TYPE_CHECK_INSTANCE_CAST((obj), NM_TYPE_DHCP_DHCPCD, NMDhcpDhcpcd))
#define NM_DHCP_DHCPCD_CLASS(klass) \
    (G_TYPE_CHECK_CLASS_CAST((klass), NM_TYPE_DHCP_DHCPCD, NMDhcpDhcpcdClass))
#define NM_IS_DHCP_DHCPCD(obj)         (G_TYPE_CHECK_INSTANCE_TYPE((obj), NM_TYPE_DHCP_DHCPCD))
#define NM_IS_DHCP_DHCPCD_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE((klass), NM_TYPE_DHCP_DHCPCD))
#define NM_DHCP_DHCPCD_GET_CLASS(obj) \
    (G_TYPE_INSTANCE_GET_CLASS((obj), NM_TYPE_DHCP_DHCPCD, NMDhcpDhcpcdClass))

typedef struct _NMDhcpDhcpcd      NMDhcpDhcpcd;
typedef struct _NMDhcpDhcpcdClass NMDhcpDhcpcdClass;

static GType nm_dhcp_dhcpcd_get_type(void);

/*****************************************************************************/

typedef struct {
    NMDhcpListener *dhcp_listener;
} NMDhcpDhcpcdPrivate;

struct _NMDhcpDhcpcd {
    NMDhcpClient        parent;
    NMDhcpDhcpcdPrivate _priv;
};

struct _NMDhcpDhcpcdClass {
    NMDhcpClientClass parent;
};

G_DEFINE_TYPE(NMDhcpDhcpcd, nm_dhcp_dhcpcd, NM_TYPE_DHCP_CLIENT)

#define NM_DHCP_DHCPCD_GET_PRIVATE(self) _NM_GET_PRIVATE(self, NMDhcpDhcpcd, NM_IS_DHCP_DHCPCD)

/*****************************************************************************/

static const char *
nm_dhcp_dhcpcd_get_path(void)
{
    return nm_utils_find_helper("dhcpcd", DHCPCD_PATH, NULL);
}

static gboolean
ip4_start(NMDhcpClient *client, const char *last_ip4_address, GError **error)
{
    NMDhcpDhcpcd *    self            = NM_DHCP_DHCPCD(client);
    gs_unref_ptrarray GPtrArray *argv = NULL;
    pid_t                        pid;
    GError *                     local;
    gs_free char *               cmd_str = NULL;
    const char *                 iface;
    const char *                 dhcpcd_path;
    const char *                 hostname;

    pid = nm_dhcp_client_get_pid(client);
    g_return_val_if_fail(pid == -1, FALSE);

    iface = nm_dhcp_client_get_iface(client);

    dhcpcd_path = nm_dhcp_dhcpcd_get_path();
    if (!dhcpcd_path) {
        nm_utils_error_set_literal(error, NM_UTILS_ERROR_UNKNOWN, "dhcpcd binary not found");
        return FALSE;
    }

    argv = g_ptr_array_new();
    g_ptr_array_add(argv, (gpointer) dhcpcd_path);

    /* Don't configure anything, we will do that instead.
     * This requires dhcpcd-9.3.3 or newer.
     * Older versions only had an option not to install a default route,
     * dhcpcd still added addresses and other routes so we no longer support that
     * as it doesn't fit how NetworkManager wants to work.
     */
    g_ptr_array_add(argv, (gpointer) "--noconfigure");

    g_ptr_array_add(argv, (gpointer) "-B"); /* Don't background on lease (disable fork()) */

    g_ptr_array_add(argv, (gpointer) "-K"); /* Disable built-in carrier detection */

    g_ptr_array_add(argv, (gpointer) "-L"); /* Disable built-in IPv4LL */

    /* --noarp. Don't request or claim the address by ARP; this also disables IPv4LL. */
    g_ptr_array_add(argv, (gpointer) "-A");

    g_ptr_array_add(argv, (gpointer) "-c"); /* Set script file */
    g_ptr_array_add(argv, (gpointer) nm_dhcp_helper_path);

    /* IPv4-only for now.  NetworkManager knows better than dhcpcd when to
     * run IPv6, and dhcpcd's automatic Router Solicitations cause problems
     * with devices that don't expect them.
     */
    g_ptr_array_add(argv, (gpointer) "-4");

    hostname = nm_dhcp_client_get_hostname(client);

    if (hostname) {
        if (NM_FLAGS_HAS(nm_dhcp_client_get_client_flags(client), NM_DHCP_CLIENT_FLAGS_USE_FQDN)) {
            g_ptr_array_add(argv, (gpointer) "-h");
            g_ptr_array_add(argv, (gpointer) hostname);
            g_ptr_array_add(argv, (gpointer) "-F");
            g_ptr_array_add(argv, (gpointer) "both");
        } else {
            g_ptr_array_add(argv, (gpointer) "-h");
            g_ptr_array_add(argv, (gpointer) hostname);
        }
    }

    g_ptr_array_add(argv, (gpointer) iface);
    g_ptr_array_add(argv, NULL);

    _LOGD("running: %s", (cmd_str = g_strjoinv(" ", (char **) argv->pdata)));

    if (!g_spawn_async(NULL,
                       (char **) argv->pdata,
                       NULL,
                       G_SPAWN_STDOUT_TO_DEV_NULL | G_SPAWN_STDERR_TO_DEV_NULL
                           | G_SPAWN_DO_NOT_REAP_CHILD,
                       nm_utils_setpgid,
                       NULL,
                       &pid,
                       &local)) {
        nm_utils_error_set(error,
                           NM_UTILS_ERROR_UNKNOWN,
                           "dhcpcd failed to start: %s",
                           local->message);
        g_error_free(local);
        return FALSE;
    }

    nm_assert(pid > 0);
    _LOGI("dhcpcd started with pid %d", pid);
    nm_dhcp_client_watch_child(client, pid);
    return TRUE;
}

static void
stop(NMDhcpClient *client, gboolean release)
{
    NMDhcpDhcpcd *self = NM_DHCP_DHCPCD(client);
    pid_t         pid;
    int           sig, errsv;

    pid = nm_dhcp_client_get_pid(client);
    if (pid > 1) {
        sig = release ? SIGALRM : SIGTERM;
        _LOGD("sending %s to dhcpcd pid %d", sig == SIGALRM ? "SIGALRM" : "SIGTERM", pid);

        /* dhcpcd-9.x features privilege separation.
         * It's not our job to track all these processes so we rely on dhcpcd
         * to always cleanup after itself.
         * Because it also re-parents itself to PID 1, the process cannot be
         * reaped or waited for.
         * As such, just send the correct signal.
         */
        if (kill(pid, sig) == -1) {
            errsv = errno;
            _LOGE("failed to kill dhcpcd %d:%s", errsv, strerror(errsv));
        }

        /* When this function exits NM expects the PID to be -1.
         * This means we also need to stop watching the pid.
         * If we need to know the exit status then we need to refactor NM
         * to allow a non -1 to mean we're waiting to exit still.
         */
        nm_dhcp_client_stop_watch_child(client, pid);
    }
}

/*****************************************************************************/

static void
nm_dhcp_dhcpcd_init(NMDhcpDhcpcd *self)
{
    NMDhcpDhcpcdPrivate *priv = NM_DHCP_DHCPCD_GET_PRIVATE(self);

    priv->dhcp_listener = g_object_ref(nm_dhcp_listener_get());
    g_signal_connect(priv->dhcp_listener,
                     NM_DHCP_LISTENER_EVENT,
                     G_CALLBACK(nm_dhcp_client_handle_event),
                     self);
}

static void
dispose(GObject *object)
{
    NMDhcpDhcpcdPrivate *priv = NM_DHCP_DHCPCD_GET_PRIVATE(object);

    if (priv->dhcp_listener) {
        g_signal_handlers_disconnect_by_func(priv->dhcp_listener,
                                             G_CALLBACK(nm_dhcp_client_handle_event),
                                             NM_DHCP_DHCPCD(object));
        g_clear_object(&priv->dhcp_listener);
    }

    G_OBJECT_CLASS(nm_dhcp_dhcpcd_parent_class)->dispose(object);
}

static void
nm_dhcp_dhcpcd_class_init(NMDhcpDhcpcdClass *dhcpcd_class)
{
    NMDhcpClientClass *client_class = NM_DHCP_CLIENT_CLASS(dhcpcd_class);
    GObjectClass *     object_class = G_OBJECT_CLASS(dhcpcd_class);

    object_class->dispose = dispose;

    client_class->ip4_start = ip4_start;
    client_class->stop      = stop;
}

const NMDhcpClientFactory _nm_dhcp_client_factory_dhcpcd = {
    .name       = "dhcpcd",
    .get_type_4 = nm_dhcp_dhcpcd_get_type,
    .get_path   = nm_dhcp_dhcpcd_get_path,
};

#endif /* WITH_DHCPCD */