ifenslave: new applet. closes bug 115.

5 files changed, 656 insertions, 0 deletions

diff --git a/include/applets.h b/include/applets.h
index cdb19958c..b2e89ee85 100644
--- a/include/applets.h
+++ b/include/applets.h
@@ -186,6 +186,7 @@ USE_HWCLOCK(APPLET(hwclock, _BB_DIR_SBIN, _BB_SUID_NEVER))
 USE_ID(APPLET(id, _BB_DIR_USR_BIN, _BB_SUID_NEVER))
 USE_IFCONFIG(APPLET(ifconfig, _BB_DIR_SBIN, _BB_SUID_NEVER))
 USE_IFUPDOWN(APPLET_ODDNAME(ifdown, ifupdown, _BB_DIR_SBIN, _BB_SUID_NEVER, ifdown))
+USE_IFENSLAVE(APPLET(ifenslave, _BB_DIR_SBIN, _BB_SUID_NEVER))
 USE_IFUPDOWN(APPLET_ODDNAME(ifup, ifupdown, _BB_DIR_SBIN, _BB_SUID_NEVER, ifup))
 USE_INETD(APPLET(inetd, _BB_DIR_USR_SBIN, _BB_SUID_NEVER))
 USE_INIT(APPLET(init, _BB_DIR_SBIN, _BB_SUID_NEVER))
diff --git a/include/usage.h b/include/usage.h
index 359f88d27..3ef421197 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -1563,6 +1563,32 @@ USE_FEATURE_BRCTL_FANCY("\n" \
        "	[mem_start NN] [io_addr NN] [irq NN]\n") \
        "	[up|down] ..."
 
+#define ifenslave_trivial_usage \
+       "[-cdf] master-iface <slave-iface...>"
+#define ifenslave_full_usage \
+       "Configure network interfaces for parallel routing\n\n" \
+       "Options:" \
+     "\n	-c, --change-active	Change active slave" \
+     "\n	-d, --detach		Remove slave interface from bonding device" \
+     "\n	-f, --force		Force, even if interface is not Ethernet" \
+/*   "\n	-r, --receive-slave	Create a receive-only slave" */
+#define ifenslave_example_usage \
+       "To create a bond device, simply follow these three steps :\n" \
+       "- ensure that the required drivers are properly loaded :\n" \
+       "  # modprobe bonding ; modprobe <3c59x|eepro100|pcnet32|tulip|...>\n" \
+       "- assign an IP address to the bond device :\n" \
+       "  # ifconfig bond0 <addr> netmask <mask> broadcast <bcast>\n" \
+       "- attach all the interfaces you need to the bond device :\n" \
+       "  # ifenslave bond0 eth0 eth1 eth2\n" \
+       "  If bond0 didn't have a MAC address, it will take eth0's. Then, all\n" \
+       "  interfaces attached AFTER this assignment will get the same MAC addr.\n\n" \
+       "  To detach a dead interface without setting the bond device down :\n" \
+       "   # ifenslave -d bond0 eth1\n\n" \
+       "  To set the bond device down and automatically release all the slaves :\n" \
+       "   # ifconfig bond0 down\n\n" \
+       "  To change active slave :\n" \
+       "   # ifenslave -c bond0 eth0\n"
+
 #define ifup_trivial_usage \
        "[-ahinv] ifaces..."
 #define ifup_full_usage \
diff --git a/networking/Config.in b/networking/Config.in
index 5a25d6d2b..202b65fce 100644
--- a/networking/Config.in
+++ b/networking/Config.in
@@ -292,6 +292,13 @@ config FEATURE_IFCONFIG_BROADCAST_PLUS
 	  Setting this will make ifconfig attempt to find the broadcast
 	  automatically if the value '+' is used.
 
+config IFENSLAVE
+	bool "ifenslave"
+	default n
+	help
+	  Userspace application to bind several interfaces
+	  to a logical interface (use with kernel bonding driver).
+
 config IFUPDOWN
 	bool "ifupdown"
 	default n
diff --git a/networking/Kbuild b/networking/Kbuild
index 8f309cdb2..e06a12462 100644
--- a/networking/Kbuild
+++ b/networking/Kbuild
@@ -17,6 +17,7 @@ lib-$(CONFIG_FTPPUT)       += ftpgetput.o
 lib-$(CONFIG_HOSTNAME)     += hostname.o
 lib-$(CONFIG_HTTPD)        += httpd.o
 lib-$(CONFIG_IFCONFIG)     += ifconfig.o interface.o
+lib-$(CONFIG_IFENSLAVE)    += ifenslave.o
 lib-$(CONFIG_IFUPDOWN)     += ifupdown.o
 lib-$(CONFIG_INETD)        += inetd.o
 lib-$(CONFIG_IP)           += ip.o
diff --git a/networking/ifenslave.c b/networking/ifenslave.c
new file mode 100644
index 000000000..774d7c2d2
--- /dev/null
+++ b/networking/ifenslave.c
@@ -0,0 +1,621 @@
+/* Mode: C;
+ *
+ * Mini ifenslave implementation for busybox
+ * Copyright (C) 2005 by Marc Leeman <marc.leeman@barco.com>
+ *
+ * ifenslave.c: Configure network interfaces for parallel routing.
+ *
+ *	This program controls the Linux implementation of running multiple
+ *	network interfaces in parallel.
+ *
+ * Author:	Donald Becker <becker@cesdis.gsfc.nasa.gov>
+ *		Copyright 1994-1996 Donald Becker
+ *
+ *		This program is free software; you can redistribute it
+ *		and/or modify it under the terms of the GNU General Public
+ *		License as published by the Free Software Foundation.
+ *
+ *	The author may be reached as becker@CESDIS.gsfc.nasa.gov, or C/O
+ *	Center of Excellence in Space Data and Information Sciences
+ *	   Code 930.5, Goddard Space Flight Center, Greenbelt MD 20771
+ *
+ *  Changes :
+ *    - 2000/10/02 Willy Tarreau <willy at meta-x.org> :
+ *       - few fixes. Master's MAC address is now correctly taken from
+ *         the first device when not previously set ;
+ *       - detach support : call BOND_RELEASE to detach an enslaved interface.
+ *       - give a mini-howto from command-line help : # ifenslave -h
+ *
+ *    - 2001/02/16 Chad N. Tindel <ctindel at ieee dot org> :
+ *       - Master is now brought down before setting the MAC address.  In
+ *         the 2.4 kernel you can't change the MAC address while the device is
+ *         up because you get EBUSY.
+ *
+ *    - 2001/09/13 Takao Indoh <indou dot takao at jp dot fujitsu dot com>
+ *       - Added the ability to change the active interface on a mode 1 bond
+ *         at runtime.
+ *
+ *    - 2001/10/23 Chad N. Tindel <ctindel at ieee dot org> :
+ *       - No longer set the MAC address of the master.  The bond device will
+ *         take care of this itself
+ *       - Try the SIOC*** versions of the bonding ioctls before using the
+ *         old versions
+ *    - 2002/02/18 Erik Habbinga <erik_habbinga @ hp dot com> :
+ *       - ifr2.ifr_flags was not initialized in the hwaddr_notset case,
+ *         SIOCGIFFLAGS now called before hwaddr_notset test
+ *
+ *    - 2002/10/31 Tony Cureington <tony.cureington * hp_com> :
+ *       - If the master does not have a hardware address when the first slave
+ *         is enslaved, the master is assigned the hardware address of that
+ *         slave - there is a comment in bonding.c stating "ifenslave takes
+ *         care of this now." This corrects the problem of slaves having
+ *         different hardware addresses in active-backup mode when
+ *         multiple interfaces are specified on a single ifenslave command
+ *         (ifenslave bond0 eth0 eth1).
+ *
+ *    - 2003/03/18 - Tsippy Mendelson <tsippy.mendelson at intel dot com> and
+ *                   Shmulik Hen <shmulik.hen at intel dot com>
+ *       - Moved setting the slave's mac address and openning it, from
+ *         the application to the driver. This enables support of modes
+ *         that need to use the unique mac address of each slave.
+ *         The driver also takes care of closing the slave and restoring its
+ *         original mac address upon release.
+ *         In addition, block possibility of enslaving before the master is up.
+ *         This prevents putting the system in an undefined state.
+ *
+ *    - 2003/05/01 - Amir Noam <amir.noam at intel dot com>
+ *       - Added ABI version control to restore compatibility between
+ *         new/old ifenslave and new/old bonding.
+ *       - Prevent adding an adapter that is already a slave.
+ *         Fixes the problem of stalling the transmission and leaving
+ *         the slave in a down state.
+ *
+ *    - 2003/05/01 - Shmulik Hen <shmulik.hen at intel dot com>
+ *       - Prevent enslaving if the bond device is down.
+ *         Fixes the problem of leaving the system in unstable state and
+ *         halting when trying to remove the module.
+ *       - Close socket on all abnormal exists.
+ *       - Add versioning scheme that follows that of the bonding driver.
+ *         current version is 1.0.0 as a base line.
+ *
+ *    - 2003/05/22 - Jay Vosburgh <fubar at us dot ibm dot com>
+ *	 - ifenslave -c was broken; it's now fixed
+ *	 - Fixed problem with routes vanishing from master during enslave
+ *	   processing.
+ *
+ *    - 2003/05/27 - Amir Noam <amir.noam at intel dot com>
+ *	 - Fix backward compatibility issues:
+ *	   For drivers not using ABI versions, slave was set down while
+ *	   it should be left up before enslaving.
+ *	   Also, master was not set down and the default set_mac_address()
+ *	   would fail and generate an error message in the system log.
+ * 	 - For opt_c: slave should not be set to the master's setting
+ *	   while it is running. It was already set during enslave. To
+ *	   simplify things, it is now handeled separately.
+ *
+ *    - 2003/12/01 - Shmulik Hen <shmulik.hen at intel dot com>
+ *	 - Code cleanup and style changes
+ *	   set version to 1.1.0
+ */
+
+#include "libbb.h"
+
+#include <net/if_arp.h>
+#include <linux/if_bonding.h>
+#include <linux/sockios.h>
+
+typedef unsigned long long u64; /* hack, so we may include kernel's ethtool.h */
+typedef uint32_t u32;           /* ditto */
+typedef uint16_t u16;           /* ditto */
+typedef uint8_t u8;             /* ditto */
+#include <linux/ethtool.h>
+
+
+struct dev_data {
+	struct ifreq mtu, flags, hwaddr;
+};
+
+
+enum { skfd = 3 };      /* AF_INET socket for ioctl() calls.*/
+struct globals {
+	unsigned abi_ver;       /* userland - kernel ABI version */
+	smallint hwaddr_set;    /* Master's hwaddr is set */
+	struct dev_data master;
+	struct dev_data slave;
+};
+#define G (*ptr_to_globals)
+#define abi_ver    (G.abi_ver   )
+#define hwaddr_set (G.hwaddr_set)
+#define master     (G.master    )
+#define slave      (G.slave     )
+#define INIT_G() do { \
+        PTR_TO_GLOBALS = xzalloc(sizeof(G)); \
+} while (0)
+
+
+static void get_drv_info(char *master_ifname);
+static int get_if_settings(char *ifname, struct dev_data *dd);
+static int get_slave_flags(char *slave_ifname);
+static int set_master_hwaddr(char *master_ifname, struct sockaddr *hwaddr);
+static int set_slave_hwaddr(char *slave_ifname, struct sockaddr *hwaddr);
+static int set_slave_mtu(char *slave_ifname, int mtu);
+static int set_if_flags(char *ifname, short flags);
+static int set_if_up(char *ifname, short flags);
+static int set_if_down(char *ifname, short flags);
+static int clear_if_addr(char *ifname);
+static int set_if_addr(char *master_ifname, char *slave_ifname);
+static void change_active(char *master_ifname, char *slave_ifname);
+static int enslave(char *master_ifname, char *slave_ifname);
+static int release(char *master_ifname, char *slave_ifname);
+
+
+int ifenslave_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int ifenslave_main(int argc, char **argv)
+{
+	char *master_ifname, *slave_ifname;
+	int rv;
+	int res;
+	unsigned opt;
+	enum {
+		OPT_c = (1 << 0),
+		OPT_d = (1 << 1),
+		OPT_f = (1 << 2),
+	};
+#if ENABLE_GETOPT_LONG
+	static const char ifenslave_longopts[] ALIGN1 =
+		"change-active" No_argument "c"
+		"detach"        No_argument "d"
+		"force"         No_argument "f"
+	;
+
+	applet_long_options = ifenslave_longopts;
+#endif
+	opt = getopt32(argv, "cdf");
+	argv += optind;
+	if (opt & (opt-1)) /* options check */
+		bb_show_usage();
+
+	/* Copy the interface name */
+	master_ifname = *argv++;
+
+	/* No remaining args means show all interfaces. */
+	if (!master_ifname) {
+		display_interfaces(NULL);
+		return EXIT_SUCCESS;
+	}
+
+	/* Open a basic socket */
+	xmove_fd(xsocket(AF_INET, SOCK_DGRAM, 0), skfd);
+
+	/* exchange abi version with bonding module */
+	get_drv_info(master_ifname);
+
+	slave_ifname = *argv++;
+	if (!slave_ifname) {
+		if (opt & (OPT_d|OPT_c)) {
+			display_interfaces(slave_ifname);
+			return 2; /* why? */
+		}
+		/* A single arg means show the
+		 * configuration for this interface
+		 */
+		display_interfaces(master_ifname);
+		return EXIT_SUCCESS;
+	}
+
+	res = get_if_settings(master_ifname, &master);
+	if (res) {
+		/* Probably a good reason not to go on */
+		bb_perror_msg_and_die("%s: can't get settings", master_ifname);
+	}
+
+	/* check if master is indeed a master;
+	 * if not then fail any operation
+	 */
+	if (!(master.flags.ifr_flags & IFF_MASTER))
+		bb_error_msg_and_die("%s is not a master", master_ifname);
+
+	/* check if master is up; if not then fail any operation */
+	if (!(master.flags.ifr_flags & IFF_UP))
+		bb_error_msg_and_die("%s is not up", master_ifname);
+
+	/* Only for enslaving */
+	if (!(opt & (OPT_c|OPT_d))) {
+		sa_family_t master_family = master.hwaddr.ifr_hwaddr.sa_family;
+
+		/* The family '1' is ARPHRD_ETHER for ethernet. */
+		if (master_family != 1 && !(opt & OPT_f)) {
+			bb_error_msg_and_die(
+				"%s is not ethernet-like (-f overrides)",
+				master_ifname);
+		}
+	}
+
+	/* Accepts only one slave */
+	if (opt & OPT_c) {
+		/* change active slave */
+		res = get_slave_flags(slave_ifname);
+		if (res) {
+			bb_perror_msg_and_die(
+				"%s: can't get flags", slave_ifname);
+		}
+		change_active(master_ifname, slave_ifname);
+		return EXIT_SUCCESS;
+	}
+
+	/* Accept multiple slaves */
+	res = 0;
+	do {
+		if (opt & OPT_d) {
+			/* detach a slave interface from the master */
+			rv = get_slave_flags(slave_ifname);
+			if (rv) {
+				/* Can't work with this slave. */
+				/* remember the error and skip it*/
+				bb_perror_msg(
+					"skipping %s: can't get flags",
+					slave_ifname);
+				res = rv;
+				continue;
+			}
+			rv = release(master_ifname, slave_ifname);
+			if (rv) {
+				bb_perror_msg(
+					"master %s, slave %s: "
+					"can't release",
+					master_ifname, slave_ifname);
+				res = rv;
+			}
+		} else {
+			/* attach a slave interface to the master */
+			rv = get_if_settings(slave_ifname, &slave);
+			if (rv) {
+				/* Can't work with this slave. */
+				/* remember the error and skip it*/
+				bb_perror_msg(
+					"skipping %s: can't get settings",
+					slave_ifname);
+				res = rv;
+				continue;
+			}
+			rv = enslave(master_ifname, slave_ifname);
+			if (rv) {
+				bb_perror_msg(
+					"master %s, slave %s: "
+					"can't enslave",
+					master_ifname, slave_ifname);
+				res = rv;
+			}
+		}
+	} while ((slave_ifname = *argv++) != NULL);
+
+	if (ENABLE_FEATURE_CLEAN_UP) {
+		close(skfd);
+	}
+
+	return res;
+}
+
+static void get_drv_info(char *master_ifname)
+{
+	struct ifreq ifr;
+	struct ethtool_drvinfo info;
+
+	memset(&ifr, 0, sizeof(ifr));
+	strncpy(ifr.ifr_name, master_ifname, IFNAMSIZ);
+	ifr.ifr_data = (caddr_t)&info;
+
+	info.cmd = ETHTOOL_GDRVINFO;
+	strncpy(info.driver, "ifenslave", 32);
+	snprintf(info.fw_version, 32, "%d", BOND_ABI_VERSION);
+
+	if (ioctl(skfd, SIOCETHTOOL, &ifr) < 0) {
+		if (errno == EOPNOTSUPP)
+			return;
+		bb_perror_msg_and_die("%s: SIOCETHTOOL error", master_ifname);
+	}
+
+	abi_ver = bb_strtou(info.fw_version, NULL, 0);
+	if (errno)
+		bb_error_msg_and_die("%s: SIOCETHTOOL error", master_ifname);
+
+	return;
+}
+
+static void change_active(char *master_ifname, char *slave_ifname)
+{
+	struct ifreq ifr;
+
+	if (!(slave.flags.ifr_flags & IFF_SLAVE)) {
+		bb_error_msg_and_die(
+			"%s is not a slave",
+			slave_ifname);
+	}
+
+	strncpy(ifr.ifr_name, master_ifname, IFNAMSIZ);
+	strncpy(ifr.ifr_slave, slave_ifname, IFNAMSIZ);
+	if (ioctl(skfd, SIOCBONDCHANGEACTIVE, &ifr) < 0
+	 && ioctl(skfd, BOND_CHANGE_ACTIVE_OLD, &ifr) < 0
+	) {
+		bb_perror_msg_and_die(
+			"master %s, slave %s: can't "
+			"change active",
+			master_ifname, slave_ifname);
+	}
+}
+
+static int enslave(char *master_ifname, char *slave_ifname)
+{
+	struct ifreq ifr;
+	int res;
+
+	if (slave.flags.ifr_flags & IFF_SLAVE) {
+		bb_error_msg(
+			"%s is already a slave",
+			slave_ifname);
+		return 1;
+	}
+
+	res = set_if_down(slave_ifname, slave.flags.ifr_flags);
+	if (res)
+		return res;
+
+	if (abi_ver < 2) {
+		/* Older bonding versions would panic if the slave has no IP
+		 * address, so get the IP setting from the master.
+		 */
+		res = set_if_addr(master_ifname, slave_ifname);
+		if (res) {
+			bb_perror_msg("%s: can't set address", slave_ifname);
+			return res;
+		}
+	} else {
+		res = clear_if_addr(slave_ifname);
+		if (res) {
+			bb_perror_msg("%s: can't clear address", slave_ifname);
+			return res;
+		}
+	}
+
+	if (master.mtu.ifr_mtu != slave.mtu.ifr_mtu) {
+		res = set_slave_mtu(slave_ifname, master.mtu.ifr_mtu);
+		if (res) {
+			bb_perror_msg("%s: can't set MTU", slave_ifname);
+			return res;
+		}
+	}
+
+	if (hwaddr_set) {
+		/* Master already has an hwaddr
+		 * so set it's hwaddr to the slave
+		 */
+		if (abi_ver < 1) {
+			/* The driver is using an old ABI, so
+			 * the application sets the slave's
+			 * hwaddr
+			 */
+			res = set_slave_hwaddr(slave_ifname,
+					       &(master.hwaddr.ifr_hwaddr));
+			if (res) {
+				bb_perror_msg("%s: can't set hw address",
+						slave_ifname);
+				goto undo_mtu;
+			}
+
+			/* For old ABI the application needs to bring the
+			 * slave back up
+			 */
+			res = set_if_up(slave_ifname, slave.flags.ifr_flags);
+			if (res)
+				goto undo_slave_mac;
+		}
+		/* The driver is using a new ABI,
+		 * so the driver takes care of setting
+		 * the slave's hwaddr and bringing
+		 * it up again
+		 */
+	} else {
+		/* No hwaddr for master yet, so
+		 * set the slave's hwaddr to it
+		 */
+		if (abi_ver < 1) {
+			/* For old ABI, the master needs to be
+			 * down before setting it's hwaddr
+			 */
+			res = set_if_down(master_ifname, master.flags.ifr_flags);
+			if (res)
+				goto undo_mtu;
+		}
+
+		res = set_master_hwaddr(master_ifname,
+					&(slave.hwaddr.ifr_hwaddr));
+		if (res) {
+			bb_error_msg("%s: can't set hw address",
+				master_ifname);
+			goto undo_mtu;
+		}
+
+		if (abi_ver < 1) {
+			/* For old ABI, bring the master
+			 * back up
+			 */
+			res = set_if_up(master_ifname, master.flags.ifr_flags);
+			if (res)
+				goto undo_master_mac;
+		}
+
+		hwaddr_set = 1;
+	}
+
+	/* Do the real thing */
+	strncpy(ifr.ifr_name, master_ifname, IFNAMSIZ);
+	strncpy(ifr.ifr_slave, slave_ifname, IFNAMSIZ);
+	if (ioctl(skfd, SIOCBONDENSLAVE, &ifr) < 0
+	 && ioctl(skfd, BOND_ENSLAVE_OLD, &ifr) < 0
+	) {
+		res = 1;
+	}
+
+	if (res)
+		goto undo_master_mac;
+
+	return 0;
+
+/* rollback (best effort) */
+ undo_master_mac:
+	set_master_hwaddr(master_ifname, &(master.hwaddr.ifr_hwaddr));
+	hwaddr_set = 0;
+	goto undo_mtu;
+ undo_slave_mac:
+	set_slave_hwaddr(slave_ifname, &(slave.hwaddr.ifr_hwaddr));
+ undo_mtu:
+	set_slave_mtu(slave_ifname, slave.mtu.ifr_mtu);
+	return res;
+}
+
+static int release(char *master_ifname, char *slave_ifname)
+{
+	struct ifreq ifr;
+	int res = 0;
+
+	if (!(slave.flags.ifr_flags & IFF_SLAVE)) {
+		bb_error_msg("%s is not a slave",
+			slave_ifname);
+		return 1;
+	}
+
+	strncpy(ifr.ifr_name, master_ifname, IFNAMSIZ);
+	strncpy(ifr.ifr_slave, slave_ifname, IFNAMSIZ);
+	if (ioctl(skfd, SIOCBONDRELEASE, &ifr) < 0
+	 && ioctl(skfd, BOND_RELEASE_OLD, &ifr) < 0
+	) {
+		return 1;
+	}
+	if (abi_ver < 1) {
+		/* The driver is using an old ABI, so we'll set the interface
+		 * down to avoid any conflicts due to same MAC/IP
+		 */
+		res = set_if_down(slave_ifname, slave.flags.ifr_flags);
+	}
+
+	/* set to default mtu */
+	set_slave_mtu(slave_ifname, 1500);
+
+	return res;
+}
+
+static int get_if_settings(char *ifname, struct dev_data *dd)
+{
+	int res;
+
+	strncpy(dd->mtu.ifr_name, ifname, IFNAMSIZ);
+	res = ioctl(skfd, SIOCGIFMTU, &dd->mtu);
+	strncpy(dd->flags.ifr_name, ifname, IFNAMSIZ);
+	res |= ioctl(skfd, SIOCGIFFLAGS, &dd->flags);
+	strncpy(dd->hwaddr.ifr_name, ifname, IFNAMSIZ);
+	res |= ioctl(skfd, SIOCGIFHWADDR, &dd->hwaddr);
+
+	return res;
+}
+
+static int get_slave_flags(char *slave_ifname)
+{
+	strncpy(slave.flags.ifr_name, slave_ifname, IFNAMSIZ);
+	return ioctl(skfd, SIOCGIFFLAGS, &slave.flags);
+}
+
+static int set_master_hwaddr(char *master_ifname, struct sockaddr *hwaddr)
+{
+	struct ifreq ifr;
+
+	strncpy(ifr.ifr_name, master_ifname, IFNAMSIZ);
+	memcpy(&(ifr.ifr_hwaddr), hwaddr, sizeof(struct sockaddr));
+	return ioctl(skfd, SIOCSIFHWADDR, &ifr);
+}
+
+static int set_slave_hwaddr(char *slave_ifname, struct sockaddr *hwaddr)
+{
+	struct ifreq ifr;
+
+	strncpy(ifr.ifr_name, slave_ifname, IFNAMSIZ);
+	memcpy(&(ifr.ifr_hwaddr), hwaddr, sizeof(struct sockaddr));
+	return ioctl(skfd, SIOCSIFHWADDR, &ifr);
+}
+
+static int set_slave_mtu(char *slave_ifname, int mtu)
+{
+	struct ifreq ifr;
+
+	ifr.ifr_mtu = mtu;
+	strncpy(ifr.ifr_name, slave_ifname, IFNAMSIZ);
+	return ioctl(skfd, SIOCSIFMTU, &ifr);
+}
+
+static int set_if_flags(char *ifname, short flags)
+{
+	struct ifreq ifr;
+
+	ifr.ifr_flags = flags;
+	strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
+	return ioctl(skfd, SIOCSIFFLAGS, &ifr);
+}
+
+static int set_if_up(char *ifname, short flags)
+{
+	int res = set_if_flags(ifname, flags | IFF_UP);
+	if (res)
+		bb_perror_msg("%s: can't up", ifname);
+	return res;
+}
+
+static int set_if_down(char *ifname, short flags)
+{
+	int res = set_if_flags(ifname, flags & ~IFF_UP);
+	if (res)
+		bb_perror_msg("%s: can't down", ifname);
+	return res;
+}
+
+static int clear_if_addr(char *ifname)
+{
+	struct ifreq ifr;
+
+	strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
+	ifr.ifr_addr.sa_family = AF_INET;
+	memset(ifr.ifr_addr.sa_data, 0, sizeof(ifr.ifr_addr.sa_data));
+	return ioctl(skfd, SIOCSIFADDR, &ifr);
+}
+
+static int set_if_addr(char *master_ifname, char *slave_ifname)
+{
+	static const struct {
+		int g_ioctl;
+		int s_ioctl;
+	} ifra[] = {
+		{ SIOCGIFADDR,    SIOCSIFADDR    },
+		{ SIOCGIFDSTADDR, SIOCSIFDSTADDR },
+		{ SIOCGIFBRDADDR, SIOCSIFBRDADDR },
+		{ SIOCGIFNETMASK, SIOCSIFNETMASK },
+	};
+
+	struct ifreq ifr;
+	int res;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(ifra); i++) {
+		strncpy(ifr.ifr_name, master_ifname, IFNAMSIZ);
+		res = ioctl(skfd, ifra[i].g_ioctl, &ifr);
+		if (res < 0) {
+			ifr.ifr_addr.sa_family = AF_INET;
+			memset(ifr.ifr_addr.sa_data, 0,
+			       sizeof(ifr.ifr_addr.sa_data));
+		}
+
+		strncpy(ifr.ifr_name, slave_ifname, IFNAMSIZ);
+		res = ioctl(skfd, ifra[i].s_ioctl, &ifr);
+		if (res < 0)
+			return res;
+	}
+
+	return 0;
+}