busybox/networking/ifenslave.c
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   1/* Mode: C;
   2 *
   3 * Mini ifenslave implementation for busybox
   4 * Copyright (C) 2005 by Marc Leeman <marc.leeman@barco.com>
   5 *
   6 * ifenslave.c: Configure network interfaces for parallel routing.
   7 *
   8 *      This program controls the Linux implementation of running multiple
   9 *      network interfaces in parallel.
  10 *
  11 * Author:      Donald Becker <becker@cesdis.gsfc.nasa.gov>
  12 *              Copyright 1994-1996 Donald Becker
  13 *
  14 *              This program is free software; you can redistribute it
  15 *              and/or modify it under the terms of the GNU General Public
  16 *              License as published by the Free Software Foundation.
  17 *
  18 *      The author may be reached as becker@CESDIS.gsfc.nasa.gov, or C/O
  19 *      Center of Excellence in Space Data and Information Sciences
  20 *         Code 930.5, Goddard Space Flight Center, Greenbelt MD 20771
  21 *
  22 *  Changes :
  23 *    - 2000/10/02 Willy Tarreau <willy at meta-x.org> :
  24 *       - few fixes. Master's MAC address is now correctly taken from
  25 *         the first device when not previously set ;
  26 *       - detach support : call BOND_RELEASE to detach an enslaved interface.
  27 *       - give a mini-howto from command-line help : # ifenslave -h
  28 *
  29 *    - 2001/02/16 Chad N. Tindel <ctindel at ieee dot org> :
  30 *       - Master is now brought down before setting the MAC address.  In
  31 *         the 2.4 kernel you can't change the MAC address while the device is
  32 *         up because you get EBUSY.
  33 *
  34 *    - 2001/09/13 Takao Indoh <indou dot takao at jp dot fujitsu dot com>
  35 *       - Added the ability to change the active interface on a mode 1 bond
  36 *         at runtime.
  37 *
  38 *    - 2001/10/23 Chad N. Tindel <ctindel at ieee dot org> :
  39 *       - No longer set the MAC address of the master.  The bond device will
  40 *         take care of this itself
  41 *       - Try the SIOC*** versions of the bonding ioctls before using the
  42 *         old versions
  43 *    - 2002/02/18 Erik Habbinga <erik_habbinga @ hp dot com> :
  44 *       - ifr2.ifr_flags was not initialized in the hwaddr_notset case,
  45 *         SIOCGIFFLAGS now called before hwaddr_notset test
  46 *
  47 *    - 2002/10/31 Tony Cureington <tony.cureington * hp_com> :
  48 *       - If the master does not have a hardware address when the first slave
  49 *         is enslaved, the master is assigned the hardware address of that
  50 *         slave - there is a comment in bonding.c stating "ifenslave takes
  51 *         care of this now." This corrects the problem of slaves having
  52 *         different hardware addresses in active-backup mode when
  53 *         multiple interfaces are specified on a single ifenslave command
  54 *         (ifenslave bond0 eth0 eth1).
  55 *
  56 *    - 2003/03/18 - Tsippy Mendelson <tsippy.mendelson at intel dot com> and
  57 *                   Shmulik Hen <shmulik.hen at intel dot com>
  58 *       - Moved setting the slave's mac address and opening it, from
  59 *         the application to the driver. This enables support of modes
  60 *         that need to use the unique mac address of each slave.
  61 *         The driver also takes care of closing the slave and restoring its
  62 *         original mac address upon release.
  63 *         In addition, block possibility of enslaving before the master is up.
  64 *         This prevents putting the system in an undefined state.
  65 *
  66 *    - 2003/05/01 - Amir Noam <amir.noam at intel dot com>
  67 *       - Added ABI version control to restore compatibility between
  68 *         new/old ifenslave and new/old bonding.
  69 *       - Prevent adding an adapter that is already a slave.
  70 *         Fixes the problem of stalling the transmission and leaving
  71 *         the slave in a down state.
  72 *
  73 *    - 2003/05/01 - Shmulik Hen <shmulik.hen at intel dot com>
  74 *       - Prevent enslaving if the bond device is down.
  75 *         Fixes the problem of leaving the system in unstable state and
  76 *         halting when trying to remove the module.
  77 *       - Close socket on all abnormal exists.
  78 *       - Add versioning scheme that follows that of the bonding driver.
  79 *         current version is 1.0.0 as a base line.
  80 *
  81 *    - 2003/05/22 - Jay Vosburgh <fubar at us dot ibm dot com>
  82 *       - ifenslave -c was broken; it's now fixed
  83 *       - Fixed problem with routes vanishing from master during enslave
  84 *         processing.
  85 *
  86 *    - 2003/05/27 - Amir Noam <amir.noam at intel dot com>
  87 *       - Fix backward compatibility issues:
  88 *         For drivers not using ABI versions, slave was set down while
  89 *         it should be left up before enslaving.
  90 *         Also, master was not set down and the default set_mac_address()
  91 *         would fail and generate an error message in the system log.
  92 *       - For opt_c: slave should not be set to the master's setting
  93 *         while it is running. It was already set during enslave. To
  94 *         simplify things, it is now handeled separately.
  95 *
  96 *    - 2003/12/01 - Shmulik Hen <shmulik.hen at intel dot com>
  97 *       - Code cleanup and style changes
  98 *         set version to 1.1.0
  99 */
 100//config:config IFENSLAVE
 101//config:       bool "ifenslave (13 kb)"
 102//config:       default y
 103//config:       help
 104//config:       Userspace application to bind several interfaces
 105//config:       to a logical interface (use with kernel bonding driver).
 106
 107//applet:IF_IFENSLAVE(APPLET_NOEXEC(ifenslave, ifenslave, BB_DIR_SBIN, BB_SUID_DROP, ifenslave))
 108
 109//kbuild:lib-$(CONFIG_IFENSLAVE) += ifenslave.o interface.o
 110
 111//usage:#define ifenslave_trivial_usage
 112//usage:       "[-cdf] MASTER_IFACE SLAVE_IFACE..."
 113//usage:#define ifenslave_full_usage "\n\n"
 114//usage:       "Configure network interfaces for parallel routing\n"
 115//usage:     "\n        -c      Change active slave"
 116//usage:     "\n        -d      Remove slave interface from bonding device"
 117//usage:     "\n        -f      Force, even if interface is not Ethernet"
 118/* //usage:  "\n        -r      Create a receive-only slave" */
 119//usage:
 120//usage:#define ifenslave_example_usage
 121//usage:       "To create a bond device, simply follow these three steps:\n"
 122//usage:       "- ensure that the required drivers are properly loaded:\n"
 123//usage:       "  # modprobe bonding ; modprobe <3c59x|eepro100|pcnet32|tulip|...>\n"
 124//usage:       "- assign an IP address to the bond device:\n"
 125//usage:       "  # ifconfig bond0 <addr> netmask <mask> broadcast <bcast>\n"
 126//usage:       "- attach all the interfaces you need to the bond device:\n"
 127//usage:       "  # ifenslave bond0 eth0 eth1 eth2\n"
 128//usage:       "  If bond0 didn't have a MAC address, it will take eth0's. Then, all\n"
 129//usage:       "  interfaces attached AFTER this assignment will get the same MAC addr.\n\n"
 130//usage:       "  To detach a dead interface without setting the bond device down:\n"
 131//usage:       "  # ifenslave -d bond0 eth1\n\n"
 132//usage:       "  To set the bond device down and automatically release all the slaves:\n"
 133//usage:       "  # ifconfig bond0 down\n\n"
 134//usage:       "  To change active slave:\n"
 135//usage:       "  # ifenslave -c bond0 eth0\n"
 136
 137#include "libbb.h"
 138
 139/* #include <net/if.h> - no. linux/if_bonding.h pulls in linux/if.h */
 140#include <linux/if.h>
 141//#include <net/if_arp.h> - not needed?
 142#include <linux/if_bonding.h>
 143#include <linux/sockios.h>
 144#include "fix_u32.h" /* hack, so we may include kernel's ethtool.h */
 145#include <linux/ethtool.h>
 146#ifndef BOND_ABI_VERSION
 147# define BOND_ABI_VERSION 2
 148#endif
 149#ifndef IFNAMSIZ
 150# define IFNAMSIZ 16
 151#endif
 152
 153
 154struct dev_data {
 155        struct ifreq mtu, flags, hwaddr;
 156};
 157
 158
 159enum { skfd = 3 };      /* AF_INET socket for ioctl() calls. */
 160struct globals {
 161        unsigned abi_ver;       /* userland - kernel ABI version */
 162        smallint hwaddr_set;    /* Master's hwaddr is set */
 163        struct dev_data master;
 164        struct dev_data slave;
 165};
 166#define G (*ptr_to_globals)
 167#define abi_ver    (G.abi_ver   )
 168#define hwaddr_set (G.hwaddr_set)
 169#define master     (G.master    )
 170#define slave      (G.slave     )
 171#define INIT_G() do { \
 172        SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
 173} while (0)
 174
 175
 176/* NOINLINEs are placed where it results in smaller code (gcc 4.3.1) */
 177
 178static int ioctl_on_skfd(unsigned request, struct ifreq *ifr)
 179{
 180        return ioctl(skfd, request, ifr);
 181}
 182
 183static int set_ifrname_and_do_ioctl(unsigned request, struct ifreq *ifr, const char *ifname)
 184{
 185        strncpy_IFNAMSIZ(ifr->ifr_name, ifname);
 186        return ioctl_on_skfd(request, ifr);
 187}
 188
 189static int get_if_settings(char *ifname, struct dev_data *dd)
 190{
 191        int res;
 192
 193        res = set_ifrname_and_do_ioctl(SIOCGIFMTU, &dd->mtu, ifname);
 194        res |= set_ifrname_and_do_ioctl(SIOCGIFFLAGS, &dd->flags, ifname);
 195        res |= set_ifrname_and_do_ioctl(SIOCGIFHWADDR, &dd->hwaddr, ifname);
 196
 197        return res;
 198}
 199
 200static int get_slave_flags(char *slave_ifname)
 201{
 202        return set_ifrname_and_do_ioctl(SIOCGIFFLAGS, &slave.flags, slave_ifname);
 203}
 204
 205static int set_hwaddr(char *ifname, struct sockaddr *hwaddr)
 206{
 207        struct ifreq ifr;
 208
 209        memcpy(&(ifr.ifr_hwaddr), hwaddr, sizeof(*hwaddr));
 210        return set_ifrname_and_do_ioctl(SIOCSIFHWADDR, &ifr, ifname);
 211}
 212
 213static int set_mtu(char *ifname, int mtu)
 214{
 215        struct ifreq ifr;
 216
 217        ifr.ifr_mtu = mtu;
 218        return set_ifrname_and_do_ioctl(SIOCSIFMTU, &ifr, ifname);
 219}
 220
 221static int set_if_flags(char *ifname, int flags)
 222{
 223        struct ifreq ifr;
 224
 225        ifr.ifr_flags = flags;
 226        return set_ifrname_and_do_ioctl(SIOCSIFFLAGS, &ifr, ifname);
 227}
 228
 229static int set_if_up(char *ifname, int flags)
 230{
 231        int res = set_if_flags(ifname, flags | IFF_UP);
 232        if (res)
 233                bb_perror_msg("%s: can't up", ifname);
 234        return res;
 235}
 236
 237static int set_if_down(char *ifname, int flags)
 238{
 239        int res = set_if_flags(ifname, flags & ~IFF_UP);
 240        if (res)
 241                bb_perror_msg("%s: can't down", ifname);
 242        return res;
 243}
 244
 245static int clear_if_addr(char *ifname)
 246{
 247        struct ifreq ifr;
 248
 249        ifr.ifr_addr.sa_family = AF_INET;
 250        memset(ifr.ifr_addr.sa_data, 0, sizeof(ifr.ifr_addr.sa_data));
 251        return set_ifrname_and_do_ioctl(SIOCSIFADDR, &ifr, ifname);
 252}
 253
 254static int set_if_addr(char *master_ifname, char *slave_ifname)
 255{
 256#if (SIOCGIFADDR | SIOCSIFADDR \
 257  | SIOCGIFDSTADDR | SIOCSIFDSTADDR \
 258  | SIOCGIFBRDADDR | SIOCSIFBRDADDR \
 259  | SIOCGIFNETMASK | SIOCSIFNETMASK) <= 0xffff
 260#define INT uint16_t
 261#else
 262#define INT int
 263#endif
 264        static const struct {
 265                INT g_ioctl;
 266                INT s_ioctl;
 267        } ifra[] = {
 268                { SIOCGIFADDR,    SIOCSIFADDR    },
 269                { SIOCGIFDSTADDR, SIOCSIFDSTADDR },
 270                { SIOCGIFBRDADDR, SIOCSIFBRDADDR },
 271                { SIOCGIFNETMASK, SIOCSIFNETMASK },
 272        };
 273
 274        struct ifreq ifr;
 275        int res;
 276        unsigned i;
 277
 278        for (i = 0; i < ARRAY_SIZE(ifra); i++) {
 279                res = set_ifrname_and_do_ioctl(ifra[i].g_ioctl, &ifr, master_ifname);
 280                if (res < 0) {
 281                        ifr.ifr_addr.sa_family = AF_INET;
 282                        memset(ifr.ifr_addr.sa_data, 0,
 283                                sizeof(ifr.ifr_addr.sa_data));
 284                }
 285
 286                res = set_ifrname_and_do_ioctl(ifra[i].s_ioctl, &ifr, slave_ifname);
 287                if (res < 0)
 288                        return res;
 289        }
 290
 291        return 0;
 292}
 293
 294static void change_active(char *master_ifname, char *slave_ifname)
 295{
 296        struct ifreq ifr;
 297
 298        if (!(slave.flags.ifr_flags & IFF_SLAVE)) {
 299                bb_error_msg_and_die("%s is not a slave", slave_ifname);
 300        }
 301
 302        strncpy_IFNAMSIZ(ifr.ifr_slave, slave_ifname);
 303        if (set_ifrname_and_do_ioctl(SIOCBONDCHANGEACTIVE, &ifr, master_ifname)
 304         && ioctl_on_skfd(BOND_CHANGE_ACTIVE_OLD, &ifr)
 305        ) {
 306                bb_perror_msg_and_die(
 307                        "master %s, slave %s: can't "
 308                        "change active",
 309                        master_ifname, slave_ifname);
 310        }
 311}
 312
 313static NOINLINE int enslave(char *master_ifname, char *slave_ifname)
 314{
 315        struct ifreq ifr;
 316        int res;
 317
 318        if (slave.flags.ifr_flags & IFF_SLAVE) {
 319                bb_error_msg(
 320                        "%s is already a slave",
 321                        slave_ifname);
 322                return 1;
 323        }
 324
 325        res = set_if_down(slave_ifname, slave.flags.ifr_flags);
 326        if (res)
 327                return res;
 328
 329        if (abi_ver < 2) {
 330                /* Older bonding versions would panic if the slave has no IP
 331                 * address, so get the IP setting from the master.
 332                 */
 333                res = set_if_addr(master_ifname, slave_ifname);
 334                if (res) {
 335                        bb_perror_msg("%s: can't set address", slave_ifname);
 336                        return res;
 337                }
 338        } else {
 339                res = clear_if_addr(slave_ifname);
 340                if (res) {
 341                        bb_perror_msg("%s: can't clear address", slave_ifname);
 342                        return res;
 343                }
 344        }
 345
 346        if (master.mtu.ifr_mtu != slave.mtu.ifr_mtu) {
 347                res = set_mtu(slave_ifname, master.mtu.ifr_mtu);
 348                if (res) {
 349                        bb_perror_msg("%s: can't set MTU", slave_ifname);
 350                        return res;
 351                }
 352        }
 353
 354        if (hwaddr_set) {
 355                /* Master already has an hwaddr
 356                 * so set it's hwaddr to the slave
 357                 */
 358                if (abi_ver < 1) {
 359                        /* The driver is using an old ABI, so
 360                         * the application sets the slave's
 361                         * hwaddr
 362                         */
 363                        if (set_hwaddr(slave_ifname, &(master.hwaddr.ifr_hwaddr))) {
 364                                bb_perror_msg("%s: can't set hw address",
 365                                                slave_ifname);
 366                                goto undo_mtu;
 367                        }
 368
 369                        /* For old ABI the application needs to bring the
 370                         * slave back up
 371                         */
 372                        if (set_if_up(slave_ifname, slave.flags.ifr_flags))
 373                                goto undo_slave_mac;
 374                }
 375                /* The driver is using a new ABI,
 376                 * so the driver takes care of setting
 377                 * the slave's hwaddr and bringing
 378                 * it up again
 379                 */
 380        } else {
 381                /* No hwaddr for master yet, so
 382                 * set the slave's hwaddr to it
 383                 */
 384                if (abi_ver < 1) {
 385                        /* For old ABI, the master needs to be
 386                         * down before setting it's hwaddr
 387                         */
 388                        if (set_if_down(master_ifname, master.flags.ifr_flags))
 389                                goto undo_mtu;
 390                }
 391
 392                if (set_hwaddr(master_ifname, &(slave.hwaddr.ifr_hwaddr))) {
 393                        bb_error_msg("%s: can't set hw address",
 394                                master_ifname);
 395                        goto undo_mtu;
 396                }
 397
 398                if (abi_ver < 1) {
 399                        /* For old ABI, bring the master
 400                         * back up
 401                         */
 402                        if (set_if_up(master_ifname, master.flags.ifr_flags))
 403                                goto undo_master_mac;
 404                }
 405
 406                hwaddr_set = 1;
 407        }
 408
 409        /* Do the real thing */
 410        strncpy_IFNAMSIZ(ifr.ifr_slave, slave_ifname);
 411        if (set_ifrname_and_do_ioctl(SIOCBONDENSLAVE, &ifr, master_ifname)
 412         && ioctl_on_skfd(BOND_ENSLAVE_OLD, &ifr)
 413        ) {
 414                goto undo_master_mac;
 415        }
 416
 417        return 0;
 418
 419/* rollback (best effort) */
 420 undo_master_mac:
 421        set_hwaddr(master_ifname, &(master.hwaddr.ifr_hwaddr));
 422        hwaddr_set = 0;
 423        goto undo_mtu;
 424
 425 undo_slave_mac:
 426        set_hwaddr(slave_ifname, &(slave.hwaddr.ifr_hwaddr));
 427 undo_mtu:
 428        set_mtu(slave_ifname, slave.mtu.ifr_mtu);
 429        return 1;
 430}
 431
 432static int release(char *master_ifname, char *slave_ifname)
 433{
 434        struct ifreq ifr;
 435        int res = 0;
 436
 437        if (!(slave.flags.ifr_flags & IFF_SLAVE)) {
 438                bb_error_msg("%s is not a slave", slave_ifname);
 439                return 1;
 440        }
 441
 442        strncpy_IFNAMSIZ(ifr.ifr_slave, slave_ifname);
 443        if (set_ifrname_and_do_ioctl(SIOCBONDRELEASE, &ifr, master_ifname) < 0
 444         && ioctl_on_skfd(BOND_RELEASE_OLD, &ifr) < 0
 445        ) {
 446                return 1;
 447        }
 448        if (abi_ver < 1) {
 449                /* The driver is using an old ABI, so we'll set the interface
 450                 * down to avoid any conflicts due to same MAC/IP
 451                 */
 452                res = set_if_down(slave_ifname, slave.flags.ifr_flags);
 453        }
 454
 455        /* set to default mtu */
 456        set_mtu(slave_ifname, 1500);
 457
 458        return res;
 459}
 460
 461static NOINLINE void get_drv_info(char *master_ifname)
 462{
 463        struct ifreq ifr;
 464        struct ethtool_drvinfo info;
 465
 466        memset(&ifr, 0, sizeof(ifr));
 467        ifr.ifr_data = (caddr_t)&info;
 468        info.cmd = ETHTOOL_GDRVINFO;
 469        /* both fields are 32 bytes long (long enough) */
 470        strcpy(info.driver, "ifenslave");
 471        strcpy(info.fw_version, utoa(BOND_ABI_VERSION));
 472        if (set_ifrname_and_do_ioctl(SIOCETHTOOL, &ifr, master_ifname) < 0) {
 473                if (errno == EOPNOTSUPP)
 474                        return;
 475                bb_perror_msg_and_die("%s: SIOCETHTOOL error", master_ifname);
 476        }
 477
 478        abi_ver = bb_strtou(info.fw_version, NULL, 0);
 479        if (errno)
 480                bb_error_msg_and_die("%s: SIOCETHTOOL error", master_ifname);
 481}
 482
 483int ifenslave_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 484int ifenslave_main(int argc UNUSED_PARAM, char **argv)
 485{
 486        char *master_ifname, *slave_ifname;
 487        int rv;
 488        int res;
 489        unsigned opt;
 490        enum {
 491                OPT_c = (1 << 0),
 492                OPT_d = (1 << 1),
 493                OPT_f = (1 << 2),
 494        };
 495
 496        INIT_G();
 497
 498        opt = getopt32long(argv, "cdfa",
 499                "change-active\0"  No_argument "c"
 500                "detach\0"         No_argument "d"
 501                "force\0"          No_argument "f"
 502                /* "all-interfaces\0" No_argument "a" */
 503        );
 504        argv += optind;
 505        if (opt & (opt-1)) /* Only one option can be given */
 506                bb_show_usage();
 507
 508        master_ifname = *argv++;
 509
 510        /* No interface names - show all interfaces. */
 511        if (!master_ifname) {
 512                display_interfaces(NULL);
 513                return EXIT_SUCCESS;
 514        }
 515
 516        /* Open a basic socket */
 517        xmove_fd(xsocket(AF_INET, SOCK_DGRAM, 0), skfd);
 518
 519        /* Exchange abi version with bonding module */
 520        get_drv_info(master_ifname);
 521
 522        slave_ifname = *argv++;
 523        if (!slave_ifname) {
 524                if (opt & (OPT_d|OPT_c)) {
 525                        /* --change or --detach, and no slaves given -
 526                         * show all interfaces. */
 527                        display_interfaces(slave_ifname /* == NULL */);
 528                        return 2; /* why 2? */
 529                }
 530                /* A single arg means show the
 531                 * configuration for this interface
 532                 */
 533                display_interfaces(master_ifname);
 534                return EXIT_SUCCESS;
 535        }
 536
 537        if (get_if_settings(master_ifname, &master)) {
 538                /* Probably a good reason not to go on */
 539                bb_perror_msg_and_die("%s: can't get settings", master_ifname);
 540        }
 541
 542        /* Check if master is indeed a master;
 543         * if not then fail any operation
 544         */
 545        if (!(master.flags.ifr_flags & IFF_MASTER))
 546                bb_error_msg_and_die("%s is not a master", master_ifname);
 547
 548        /* Check if master is up; if not then fail any operation */
 549        if (!(master.flags.ifr_flags & IFF_UP))
 550                bb_error_msg_and_die("%s is not up", master_ifname);
 551
 552#ifdef WHY_BOTHER
 553        /* Neither -c[hange] nor -d[etach] -> it's "enslave" then;
 554         * and -f[orce] is not there too. Check that it's ethernet. */
 555        if (!(opt & (OPT_d|OPT_c|OPT_f))) {
 556                /* The family '1' is ARPHRD_ETHER for ethernet. */
 557                if (master.hwaddr.ifr_hwaddr.sa_family != 1) {
 558                        bb_error_msg_and_die(
 559                                "%s is not ethernet-like (-f overrides)",
 560                                master_ifname);
 561                }
 562        }
 563#endif
 564
 565        /* Accepts only one slave */
 566        if (opt & OPT_c) {
 567                /* Change active slave */
 568                if (get_slave_flags(slave_ifname)) {
 569                        bb_perror_msg_and_die(
 570                                "%s: can't get flags", slave_ifname);
 571                }
 572                change_active(master_ifname, slave_ifname);
 573                return EXIT_SUCCESS;
 574        }
 575
 576        /* Accepts multiple slaves */
 577        res = 0;
 578        do {
 579                if (opt & OPT_d) {
 580                        /* Detach a slave interface from the master */
 581                        rv = get_slave_flags(slave_ifname);
 582                        if (rv) {
 583                                /* Can't work with this slave, */
 584                                /* remember the error and skip it */
 585                                bb_perror_msg(
 586                                        "skipping %s: can't get %s",
 587                                        slave_ifname, "flags");
 588                                res = rv;
 589                                continue;
 590                        }
 591                        rv = release(master_ifname, slave_ifname);
 592                        if (rv) {
 593                                bb_perror_msg("can't release %s from %s",
 594                                        slave_ifname, master_ifname);
 595                                res = rv;
 596                        }
 597                } else {
 598                        /* Attach a slave interface to the master */
 599                        rv = get_if_settings(slave_ifname, &slave);
 600                        if (rv) {
 601                                /* Can't work with this slave, */
 602                                /* remember the error and skip it */
 603                                bb_perror_msg(
 604                                        "skipping %s: can't get %s",
 605                                        slave_ifname, "settings");
 606                                res = rv;
 607                                continue;
 608                        }
 609                        rv = enslave(master_ifname, slave_ifname);
 610                        if (rv) {
 611                                bb_perror_msg("can't enslave %s to %s",
 612                                        slave_ifname, master_ifname);
 613                                res = rv;
 614                        }
 615                }
 616        } while ((slave_ifname = *argv++) != NULL);
 617
 618        if (ENABLE_FEATURE_CLEAN_UP) {
 619                close(skfd);
 620        }
 621
 622        return res;
 623}
 624