devinet.c

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/*
 *      NET3    IP device support routines.
 *
 *      Version: $Id: devinet.c,v 1.44 2001/10/31 21:55:54 davem Exp $
 *
 *              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; either version
 *              2 of the License, or (at your option) any later version.
 *
 *      Derived from the IP parts of dev.c 1.0.19
 *              Authors:        Ross Biro, <bir7@leland.Stanford.Edu>
 *                              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *                              Mark Evans, <evansmp@uhura.aston.ac.uk>
 *
 *      Additional Authors:
 *              Alan Cox, <gw4pts@gw4pts.ampr.org>
 *              Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 *
 *      Changes:
 *              Alexey Kuznetsov:       pa_* fields are replaced with ifaddr lists.
 *              Cyrus Durgin:           updated for kmod
 *              Matthias Andree:        in devinet_ioctl, compare label and 
 *                                      address (4.4BSD alias style support),
 *                                      fall back to comparing just the label
 *                                      if no match found.
 */

#include <linux/config.h>
 
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/bitops.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/in.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/if_ether.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/init.h>
#include <linux/notifier.h>
#include <linux/inetdevice.h>
#include <linux/igmp.h>
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
#endif
#include <linux/kmod.h>

#include <net/ip.h>
#include <net/route.h>
#include <net/ip_fib.h>

struct ipv4_devconf ipv4_devconf = { 1, 1, 1, 1, 0, };
static struct ipv4_devconf ipv4_devconf_dflt = { 1, 1, 1, 1, 1, };

static void rtmsg_ifa(int event, struct in_ifaddr *);

static struct notifier_block *inetaddr_chain;
static void inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap, int destroy);
#ifdef CONFIG_SYSCTL
static void devinet_sysctl_register(struct in_device *in_dev, struct ipv4_devconf *p);
static void devinet_sysctl_unregister(struct ipv4_devconf *p);
#endif

int inet_ifa_count;
int inet_dev_count;

/* Locks all the inet devices. */

rwlock_t inetdev_lock = RW_LOCK_UNLOCKED;


static struct in_ifaddr * inet_alloc_ifa(void)
{
        struct in_ifaddr *ifa;

        ifa = kmalloc(sizeof(*ifa), GFP_KERNEL);
        if (ifa) {
                memset(ifa, 0, sizeof(*ifa));
                inet_ifa_count++;
        }

        return ifa;
}

static __inline__ void inet_free_ifa(struct in_ifaddr *ifa)
{
        if (ifa->ifa_dev)
                __in_dev_put(ifa->ifa_dev);
        kfree(ifa);
        inet_ifa_count--;
}

void in_dev_finish_destroy(struct in_device *idev)
{
        struct net_device *dev = idev->dev;

        BUG_TRAP(idev->ifa_list==NULL);
        BUG_TRAP(idev->mc_list==NULL);
#ifdef NET_REFCNT_DEBUG
        printk(KERN_DEBUG "in_dev_finish_destroy: %p=%s\n", idev, dev ? dev->name : "NIL");
#endif
        dev_put(dev);
        if (!idev->dead) {
                printk("Freeing alive in_device %p\n", idev);
                return;
        }
        inet_dev_count--;
        kfree(idev);
}

struct in_device *inetdev_init(struct net_device *dev)
{
        struct in_device *in_dev;

        ASSERT_RTNL();

        in_dev = kmalloc(sizeof(*in_dev), GFP_KERNEL);
        if (!in_dev)
                return NULL;
        memset(in_dev, 0, sizeof(*in_dev));
        in_dev->lock = RW_LOCK_UNLOCKED;
        memcpy(&in_dev->cnf, &ipv4_devconf_dflt, sizeof(in_dev->cnf));
        in_dev->cnf.sysctl = NULL;
        in_dev->dev = dev;
        if ((in_dev->arp_parms = neigh_parms_alloc(dev, &arp_tbl)) == NULL) {
                kfree(in_dev);
                return NULL;
        }
        inet_dev_count++;
        /* Reference in_dev->dev */
        dev_hold(dev);
#ifdef CONFIG_SYSCTL
        neigh_sysctl_register(dev, in_dev->arp_parms, NET_IPV4, NET_IPV4_NEIGH, "ipv4");
#endif
        write_lock_bh(&inetdev_lock);
        dev->ip_ptr = in_dev;
        /* Account for reference dev->ip_ptr */
        in_dev_hold(in_dev);
        write_unlock_bh(&inetdev_lock);
#ifdef CONFIG_SYSCTL
        devinet_sysctl_register(in_dev, &in_dev->cnf);
#endif
        if (dev->flags&IFF_UP)
                ip_mc_up(in_dev);
        return in_dev;
}

static void inetdev_destroy(struct in_device *in_dev)
{
        struct in_ifaddr *ifa;

        ASSERT_RTNL();

        in_dev->dead = 1;

        ip_mc_destroy_dev(in_dev);

        while ((ifa = in_dev->ifa_list) != NULL) {
                inet_del_ifa(in_dev, &in_dev->ifa_list, 0);
                inet_free_ifa(ifa);
        }

#ifdef CONFIG_SYSCTL
        devinet_sysctl_unregister(&in_dev->cnf);
#endif
        write_lock_bh(&inetdev_lock);
        in_dev->dev->ip_ptr = NULL;
        /* in_dev_put following below will kill the in_device */
        write_unlock_bh(&inetdev_lock);


        neigh_parms_release(&arp_tbl, in_dev->arp_parms);
        in_dev_put(in_dev);
}

int inet_addr_onlink(struct in_device *in_dev, u32 a, u32 b)
{
        read_lock(&in_dev->lock);
        for_primary_ifa(in_dev) {
                if (inet_ifa_match(a, ifa)) {
                        if (!b || inet_ifa_match(b, ifa)) {
                                read_unlock(&in_dev->lock);
                                return 1;
                        }
                }
        } endfor_ifa(in_dev);
        read_unlock(&in_dev->lock);
        return 0;
} 

static void
inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap, int destroy)
{
        struct in_ifaddr *ifa1 = *ifap;

        ASSERT_RTNL();

        /* 1. Deleting primary ifaddr forces deletion all secondaries */

        if (!(ifa1->ifa_flags&IFA_F_SECONDARY)) {
                struct in_ifaddr *ifa;
                struct in_ifaddr **ifap1 = &ifa1->ifa_next;

                while ((ifa=*ifap1) != NULL) {
                        if (!(ifa->ifa_flags&IFA_F_SECONDARY) ||
                            ifa1->ifa_mask != ifa->ifa_mask ||
                            !inet_ifa_match(ifa1->ifa_address, ifa)) {
                                ifap1 = &ifa->ifa_next;
                                continue;
                        }
                        write_lock_bh(&in_dev->lock);
                        *ifap1 = ifa->ifa_next;
                        write_unlock_bh(&in_dev->lock);

                        rtmsg_ifa(RTM_DELADDR, ifa);
                        notifier_call_chain(&inetaddr_chain, NETDEV_DOWN, ifa);
                        inet_free_ifa(ifa);
                }
        }

        /* 2. Unlink it */

        write_lock_bh(&in_dev->lock);
        *ifap = ifa1->ifa_next;
        write_unlock_bh(&in_dev->lock);

        /* 3. Announce address deletion */

        /* Send message first, then call notifier.
           At first sight, FIB update triggered by notifier
           will refer to already deleted ifaddr, that could confuse
           netlink listeners. It is not true: look, gated sees
           that route deleted and if it still thinks that ifaddr
           is valid, it will try to restore deleted routes... Grr.
           So that, this order is correct.
         */
        rtmsg_ifa(RTM_DELADDR, ifa1);
        notifier_call_chain(&inetaddr_chain, NETDEV_DOWN, ifa1);
        if (destroy) {
                inet_free_ifa(ifa1);

                if (in_dev->ifa_list == NULL)
                        inetdev_destroy(in_dev);
        }
}

static int
inet_insert_ifa(struct in_ifaddr *ifa)
{
        struct in_device *in_dev = ifa->ifa_dev;
        struct in_ifaddr *ifa1, **ifap, **last_primary;

        ASSERT_RTNL();

        if (ifa->ifa_local == 0) {
                inet_free_ifa(ifa);
                return 0;
        }

        ifa->ifa_flags &= ~IFA_F_SECONDARY;
        last_primary = &in_dev->ifa_list;

        for (ifap=&in_dev->ifa_list; (ifa1=*ifap)!=NULL; ifap=&ifa1->ifa_next) {
                if (!(ifa1->ifa_flags&IFA_F_SECONDARY) && ifa->ifa_scope <= ifa1->ifa_scope)
                        last_primary = &ifa1->ifa_next;
                if (ifa1->ifa_mask == ifa->ifa_mask && inet_ifa_match(ifa1->ifa_address, ifa)) {
                        if (ifa1->ifa_local == ifa->ifa_local) {
                                inet_free_ifa(ifa);
                                return -EEXIST;
                        }
                        if (ifa1->ifa_scope != ifa->ifa_scope) {
                                inet_free_ifa(ifa);
                                return -EINVAL;
                        }
                        ifa->ifa_flags |= IFA_F_SECONDARY;
                }
        }

        if (!(ifa->ifa_flags&IFA_F_SECONDARY)) {
                net_srandom(ifa->ifa_local);
                ifap = last_primary;
        }

        ifa->ifa_next = *ifap;
        write_lock_bh(&in_dev->lock);
        *ifap = ifa;
        write_unlock_bh(&in_dev->lock);

        /* Send message first, then call notifier.
           Notifier will trigger FIB update, so that
           listeners of netlink will know about new ifaddr */
        rtmsg_ifa(RTM_NEWADDR, ifa);
        notifier_call_chain(&inetaddr_chain, NETDEV_UP, ifa);

        return 0;
}

static int
inet_set_ifa(struct net_device *dev, struct in_ifaddr *ifa)
{
        struct in_device *in_dev = __in_dev_get(dev);

        ASSERT_RTNL();

        if (in_dev == NULL) {
                in_dev = inetdev_init(dev);
                if (in_dev == NULL) {
                        inet_free_ifa(ifa);
                        return -ENOBUFS;
                }
        }
        if (ifa->ifa_dev != in_dev) {
                BUG_TRAP(ifa->ifa_dev==NULL);
                in_dev_hold(in_dev);
                ifa->ifa_dev=in_dev;
        }
        if (LOOPBACK(ifa->ifa_local))
                ifa->ifa_scope = RT_SCOPE_HOST;
        return inet_insert_ifa(ifa);
}

struct in_device *inetdev_by_index(int ifindex)
{
        struct net_device *dev;
        struct in_device *in_dev = NULL;
        read_lock(&dev_base_lock);
        dev = __dev_get_by_index(ifindex);
        if (dev)
                in_dev = in_dev_get(dev);
        read_unlock(&dev_base_lock);
        return in_dev;
}

/* Called only from RTNL semaphored context. No locks. */

struct in_ifaddr *inet_ifa_byprefix(struct in_device *in_dev, u32 prefix, u32 mask)
{
        ASSERT_RTNL();

        for_primary_ifa(in_dev) {
                if (ifa->ifa_mask == mask && inet_ifa_match(prefix, ifa))
                        return ifa;
        } endfor_ifa(in_dev);
        return NULL;
}

int
inet_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
{
        struct rtattr  **rta = arg;
        struct in_device *in_dev;
        struct ifaddrmsg *ifm = NLMSG_DATA(nlh);
        struct in_ifaddr *ifa, **ifap;

        ASSERT_RTNL();

        if ((in_dev = inetdev_by_index(ifm->ifa_index)) == NULL)
                return -EADDRNOTAVAIL;
        __in_dev_put(in_dev);

        for (ifap=&in_dev->ifa_list; (ifa=*ifap)!=NULL; ifap=&ifa->ifa_next) {
                if ((rta[IFA_LOCAL-1] && memcmp(RTA_DATA(rta[IFA_LOCAL-1]), &ifa->ifa_local, 4)) ||
                    (rta[IFA_LABEL-1] && strcmp(RTA_DATA(rta[IFA_LABEL-1]), ifa->ifa_label)) ||
                    (rta[IFA_ADDRESS-1] &&
                     (ifm->ifa_prefixlen != ifa->ifa_prefixlen ||
                      !inet_ifa_match(*(u32*)RTA_DATA(rta[IFA_ADDRESS-1]), ifa))))
                        continue;
                inet_del_ifa(in_dev, ifap, 1);
                return 0;
        }

        return -EADDRNOTAVAIL;
}

int
inet_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
{
        struct rtattr **rta = arg;
        struct net_device *dev;
        struct in_device *in_dev;
        struct ifaddrmsg *ifm = NLMSG_DATA(nlh);
        struct in_ifaddr *ifa;

        ASSERT_RTNL();

        if (ifm->ifa_prefixlen > 32 || rta[IFA_LOCAL-1] == NULL)
                return -EINVAL;

        if ((dev = __dev_get_by_index(ifm->ifa_index)) == NULL)
                return -ENODEV;

        if ((in_dev = __in_dev_get(dev)) == NULL) {
                in_dev = inetdev_init(dev);
                if (!in_dev)
                        return -ENOBUFS;
        }

        if ((ifa = inet_alloc_ifa()) == NULL)
                return -ENOBUFS;

        if (rta[IFA_ADDRESS-1] == NULL)
                rta[IFA_ADDRESS-1] = rta[IFA_LOCAL-1];
        memcpy(&ifa->ifa_local, RTA_DATA(rta[IFA_LOCAL-1]), 4);
        memcpy(&ifa->ifa_address, RTA_DATA(rta[IFA_ADDRESS-1]), 4);
        ifa->ifa_prefixlen = ifm->ifa_prefixlen;
        ifa->ifa_mask = inet_make_mask(ifm->ifa_prefixlen);
        if (rta[IFA_BROADCAST-1])
                memcpy(&ifa->ifa_broadcast, RTA_DATA(rta[IFA_BROADCAST-1]), 4);
        if (rta[IFA_ANYCAST-1])
                memcpy(&ifa->ifa_anycast, RTA_DATA(rta[IFA_ANYCAST-1]), 4);
        ifa->ifa_flags = ifm->ifa_flags;
        ifa->ifa_scope = ifm->ifa_scope;
        in_dev_hold(in_dev);
        ifa->ifa_dev = in_dev;
        if (rta[IFA_LABEL-1])
                memcpy(ifa->ifa_label, RTA_DATA(rta[IFA_LABEL-1]), IFNAMSIZ);
        else
                memcpy(ifa->ifa_label, dev->name, IFNAMSIZ);

        return inet_insert_ifa(ifa);
}

/* 
 *      Determine a default network mask, based on the IP address. 
 */

static __inline__ int inet_abc_len(u32 addr)
{
        if (ZERONET(addr))
                return 0;

        addr = ntohl(addr);
        if (IN_CLASSA(addr)) 
                return 8;
        if (IN_CLASSB(addr)) 
                return 16;
        if (IN_CLASSC(addr)) 
                return 24;

        /*
         *      Something else, probably a multicast. 
         */
         
        return -1;
}


int devinet_ioctl(unsigned int cmd, void *arg)
{
        struct ifreq ifr;
        struct sockaddr_in sin_orig;
        struct sockaddr_in *sin = (struct sockaddr_in *)&ifr.ifr_addr;
        struct in_device *in_dev;
        struct in_ifaddr **ifap = NULL;
        struct in_ifaddr *ifa = NULL;
        struct net_device *dev;
        char *colon;
        int ret = 0;
        int tryaddrmatch = 0;

        /*
         *      Fetch the caller's info block into kernel space
         */

        if (copy_from_user(&ifr, arg, sizeof(struct ifreq)))
                return -EFAULT;
        ifr.ifr_name[IFNAMSIZ-1] = 0;

        /* save original address for comparison */
        memcpy(&sin_orig, sin, sizeof(*sin));

        colon = strchr(ifr.ifr_name, ':');
        if (colon)
                *colon = 0;

#ifdef CONFIG_KMOD
        dev_load(ifr.ifr_name);
#endif

        switch(cmd) {
        case SIOCGIFADDR:       /* Get interface address */
        case SIOCGIFBRDADDR:    /* Get the broadcast address */
        case SIOCGIFDSTADDR:    /* Get the destination address */
        case SIOCGIFNETMASK:    /* Get the netmask for the interface */
                /* Note that these ioctls will not sleep,
                   so that we do not impose a lock.
                   One day we will be forced to put shlock here (I mean SMP)
                 */
                tryaddrmatch = (sin_orig.sin_family == AF_INET);
                memset(sin, 0, sizeof(*sin));
                sin->sin_family = AF_INET;
                break;

        case SIOCSIFFLAGS:
                if (!capable(CAP_NET_ADMIN))
                        return -EACCES;
                break;
        case SIOCSIFADDR:       /* Set interface address (and family) */
        case SIOCSIFBRDADDR:    /* Set the broadcast address */
        case SIOCSIFDSTADDR:    /* Set the destination address */
        case SIOCSIFNETMASK:    /* Set the netmask for the interface */
                if (!capable(CAP_NET_ADMIN))
                        return -EACCES;
                if (sin->sin_family != AF_INET)
                        return -EINVAL;
                break;
        default:
                return -EINVAL;
        }

        dev_probe_lock();
        rtnl_lock();

        if ((dev = __dev_get_by_name(ifr.ifr_name)) == NULL) {
                ret = -ENODEV;
                goto done;
        }

        if (colon)
                *colon = ':';

        if ((in_dev=__in_dev_get(dev)) != NULL) {
                if (tryaddrmatch) {
                        /* Matthias Andree */
                        /* compare label and address (4.4BSD style) */
                        /* note: we only do this for a limited set of ioctls
                           and only if the original address family was AF_INET.
                           This is checked above. */
                        for (ifap=&in_dev->ifa_list; (ifa=*ifap) != NULL; ifap=&ifa->ifa_next) {
                                if ((strcmp(ifr.ifr_name, ifa->ifa_label) == 0)
                                    && (sin_orig.sin_addr.s_addr == ifa->ifa_address)) {
                                        break; /* found */
                                }
                        }
                }
                /* we didn't get a match, maybe the application is
                   4.3BSD-style and passed in junk so we fall back to 
                   comparing just the label */
                if (ifa == NULL) {
                        for (ifap=&in_dev->ifa_list; (ifa=*ifap) != NULL; ifap=&ifa->ifa_next)
                                if (strcmp(ifr.ifr_name, ifa->ifa_label) == 0)
                                        break;
                }
        }

        if (ifa == NULL && cmd != SIOCSIFADDR && cmd != SIOCSIFFLAGS) {
                ret = -EADDRNOTAVAIL;
                goto done;
        }

        switch(cmd) {
                case SIOCGIFADDR:       /* Get interface address */
                        sin->sin_addr.s_addr = ifa->ifa_local;
                        goto rarok;

                case SIOCGIFBRDADDR:    /* Get the broadcast address */
                        sin->sin_addr.s_addr = ifa->ifa_broadcast;
                        goto rarok;

                case SIOCGIFDSTADDR:    /* Get the destination address */
                        sin->sin_addr.s_addr = ifa->ifa_address;
                        goto rarok;

                case SIOCGIFNETMASK:    /* Get the netmask for the interface */
                        sin->sin_addr.s_addr = ifa->ifa_mask;
                        goto rarok;

                case SIOCSIFFLAGS:
                        if (colon) {
                                if (ifa == NULL) {
                                        ret = -EADDRNOTAVAIL;
                                        break;
                                }
                                if (!(ifr.ifr_flags&IFF_UP))
                                        inet_del_ifa(in_dev, ifap, 1);
                                break;
                        }
                        ret = dev_change_flags(dev, ifr.ifr_flags);
                        break;
        
                case SIOCSIFADDR:       /* Set interface address (and family) */
                        if (inet_abc_len(sin->sin_addr.s_addr) < 0) {
                                ret = -EINVAL;
                                break;
                        }

                        if (!ifa) {
                                if ((ifa = inet_alloc_ifa()) == NULL) {
                                        ret = -ENOBUFS;
                                        break;
                                }
                                if (colon)
                                        memcpy(ifa->ifa_label, ifr.ifr_name, IFNAMSIZ);
                                else
                                        memcpy(ifa->ifa_label, dev->name, IFNAMSIZ);
                        } else {
                                ret = 0;
                                if (ifa->ifa_local == sin->sin_addr.s_addr)
                                        break;
                                inet_del_ifa(in_dev, ifap, 0);
                                ifa->ifa_broadcast = 0;
                                ifa->ifa_anycast = 0;
                        }

                        ifa->ifa_address =
                        ifa->ifa_local = sin->sin_addr.s_addr;

                        if (!(dev->flags&IFF_POINTOPOINT)) {
                                ifa->ifa_prefixlen = inet_abc_len(ifa->ifa_address);
                                ifa->ifa_mask = inet_make_mask(ifa->ifa_prefixlen);
                                if ((dev->flags&IFF_BROADCAST) && ifa->ifa_prefixlen < 31)
                                        ifa->ifa_broadcast = ifa->ifa_address|~ifa->ifa_mask;
                        } else {
                                ifa->ifa_prefixlen = 32;
                                ifa->ifa_mask = inet_make_mask(32);
                        }
                        ret = inet_set_ifa(dev, ifa);
                        break;

                case SIOCSIFBRDADDR:    /* Set the broadcast address */
                        if (ifa->ifa_broadcast != sin->sin_addr.s_addr) {
                                inet_del_ifa(in_dev, ifap, 0);
                                ifa->ifa_broadcast = sin->sin_addr.s_addr;
                                inet_insert_ifa(ifa);
                        }
                        break;
        
                case SIOCSIFDSTADDR:    /* Set the destination address */
                        if (ifa->ifa_address != sin->sin_addr.s_addr) {
                                if (inet_abc_len(sin->sin_addr.s_addr) < 0) {
                                        ret = -EINVAL;
                                        break;
                                }
                                inet_del_ifa(in_dev, ifap, 0);
                                ifa->ifa_address = sin->sin_addr.s_addr;
                                inet_insert_ifa(ifa);
                        }
                        break;

                case SIOCSIFNETMASK:    /* Set the netmask for the interface */

                        /*
                         *      The mask we set must be legal.
                         */
                        if (bad_mask(sin->sin_addr.s_addr, 0)) {
                                ret = -EINVAL;
                                break;
                        }

                        if (ifa->ifa_mask != sin->sin_addr.s_addr) {
                                inet_del_ifa(in_dev, ifap, 0);
                                ifa->ifa_mask = sin->sin_addr.s_addr;
                                ifa->ifa_prefixlen = inet_mask_len(ifa->ifa_mask);
                                inet_insert_ifa(ifa);
                        }
                        break;
        }
done:
        rtnl_unlock();
        dev_probe_unlock();
        return ret;

rarok:
        rtnl_unlock();
        dev_probe_unlock();
        if (copy_to_user(arg, &ifr, sizeof(struct ifreq)))
                return -EFAULT;
        return 0;
}

static int
inet_gifconf(struct net_device *dev, char *buf, int len)
{
        struct in_device *in_dev = __in_dev_get(dev);
        struct in_ifaddr *ifa;
        struct ifreq ifr;
        int done=0;

        if (in_dev==NULL || (ifa=in_dev->ifa_list)==NULL)
                return 0;

        for ( ; ifa; ifa = ifa->ifa_next) {
                if (!buf) {
                        done += sizeof(ifr);
                        continue;
                }
                if (len < (int) sizeof(ifr))
                        return done;
                memset(&ifr, 0, sizeof(struct ifreq));
                if (ifa->ifa_label)
                        strcpy(ifr.ifr_name, ifa->ifa_label);
                else
                        strcpy(ifr.ifr_name, dev->name);

                (*(struct sockaddr_in *) &ifr.ifr_addr).sin_family = AF_INET;
                (*(struct sockaddr_in *) &ifr.ifr_addr).sin_addr.s_addr = ifa->ifa_local;

                if (copy_to_user(buf, &ifr, sizeof(struct ifreq)))
                        return -EFAULT;
                buf += sizeof(struct ifreq);
                len -= sizeof(struct ifreq);
                done += sizeof(struct ifreq);
        }
        return done;
}

u32 inet_select_addr(const struct net_device *dev, u32 dst, int scope)
{
        u32 addr = 0;
        struct in_device *in_dev;

        read_lock(&inetdev_lock);
        in_dev = __in_dev_get(dev);
        if (in_dev == NULL) {
                read_unlock(&inetdev_lock);
                return 0;
        }

        read_lock(&in_dev->lock);
        for_primary_ifa(in_dev) {
                if (ifa->ifa_scope > scope)
                        continue;
                if (!dst || inet_ifa_match(dst, ifa)) {
                        addr = ifa->ifa_local;
                        break;
                }
                if (!addr)
                        addr = ifa->ifa_local;
        } endfor_ifa(in_dev);
        read_unlock(&in_dev->lock);
        read_unlock(&inetdev_lock);

        if (addr)
                return addr;

        /* Not loopback addresses on loopback should be preferred
           in this case. It is importnat that lo is the first interface
           in dev_base list.
         */
        read_lock(&dev_base_lock);
        read_lock(&inetdev_lock);
        for (dev=dev_base; dev; dev=dev->next) {
                if ((in_dev=__in_dev_get(dev)) == NULL)
                        continue;

                read_lock(&in_dev->lock);
                for_primary_ifa(in_dev) {
                        if (ifa->ifa_scope != RT_SCOPE_LINK &&
                            ifa->ifa_scope <= scope) {
                                read_unlock(&in_dev->lock);
                                read_unlock(&inetdev_lock);
                                read_unlock(&dev_base_lock);
                                return ifa->ifa_local;
                        }
                } endfor_ifa(in_dev);
                read_unlock(&in_dev->lock);
        }
        read_unlock(&inetdev_lock);
        read_unlock(&dev_base_lock);

        return 0;
}

/*
 *      Device notifier
 */

int register_inetaddr_notifier(struct notifier_block *nb)
{
        return notifier_chain_register(&inetaddr_chain, nb);
}

int unregister_inetaddr_notifier(struct notifier_block *nb)
{
        return notifier_chain_unregister(&inetaddr_chain,nb);
}

/* Rename ifa_labels for a device name change. Make some effort to preserve existing
 * alias numbering and to create unique labels if possible.
*/
static void inetdev_changename(struct net_device *dev, struct in_device *in_dev)
{ 
        struct in_ifaddr *ifa;
        int named = 0;

        for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) { 
                char old[IFNAMSIZ], *dot; 

                memcpy(old, ifa->ifa_label, IFNAMSIZ);
                memcpy(ifa->ifa_label, dev->name, IFNAMSIZ); 
                if (named++ == 0)
                        continue;
                dot = strchr(ifa->ifa_label, ':');
                if (dot == NULL) { 
                        sprintf(old, ":%d", named); 
                        dot = old;
                }
                if (strlen(dot) + strlen(dev->name) < IFNAMSIZ) { 
                        strcat(ifa->ifa_label, dot); 
                } else { 
                        strcpy(ifa->ifa_label + (IFNAMSIZ - strlen(dot) - 1), dot); 
                } 
        }       
} 

/* Called only under RTNL semaphore */

static int inetdev_event(struct notifier_block *this, unsigned long event, void *ptr)
{
        struct net_device *dev = ptr;
        struct in_device *in_dev = __in_dev_get(dev);

        ASSERT_RTNL();

        if (in_dev == NULL)
                return NOTIFY_DONE;

        switch (event) {
        case NETDEV_REGISTER:
                printk(KERN_DEBUG "inetdev_event: bug\n");
                dev->ip_ptr = NULL;
                break;
        case NETDEV_UP:
                if (dev->mtu < 68)
                        break;
                if (dev == &loopback_dev) {
                        struct in_ifaddr *ifa;
                        if ((ifa = inet_alloc_ifa()) != NULL) {
                                ifa->ifa_local =
                                ifa->ifa_address = htonl(INADDR_LOOPBACK);
                                ifa->ifa_prefixlen = 8;
                                ifa->ifa_mask = inet_make_mask(8);
                                in_dev_hold(in_dev);
                                ifa->ifa_dev = in_dev;
                                ifa->ifa_scope = RT_SCOPE_HOST;
                                memcpy(ifa->ifa_label, dev->name, IFNAMSIZ);
                                inet_insert_ifa(ifa);
                        }
                }
                ip_mc_up(in_dev);
                break;
        case NETDEV_DOWN:
                ip_mc_down(in_dev);
                break;
        case NETDEV_CHANGEMTU:
                if (dev->mtu >= 68)
                        break;
                /* MTU falled under 68, disable IP */
        case NETDEV_UNREGISTER:
                inetdev_destroy(in_dev);
                break;
        case NETDEV_CHANGENAME:
                /* Do not notify about label change, this event is
                 * not interesting to applications using netlink.
                 */
                inetdev_changename(dev, in_dev);
                break;
        }

        return NOTIFY_DONE;
}

struct notifier_block ip_netdev_notifier = {
        notifier_call:  inetdev_event,
};

static int inet_fill_ifaddr(struct sk_buff *skb, struct in_ifaddr *ifa,
                            u32 pid, u32 seq, int event)
{
        struct ifaddrmsg *ifm;
        struct nlmsghdr  *nlh;
        unsigned char    *b = skb->tail;

        nlh = NLMSG_PUT(skb, pid, seq, event, sizeof(*ifm));
        if (pid) nlh->nlmsg_flags |= NLM_F_MULTI;
        ifm = NLMSG_DATA(nlh);
        ifm->ifa_family = AF_INET;
        ifm->ifa_prefixlen = ifa->ifa_prefixlen;
        ifm->ifa_flags = ifa->ifa_flags|IFA_F_PERMANENT;
        ifm->ifa_scope = ifa->ifa_scope;
        ifm->ifa_index = ifa->ifa_dev->dev->ifindex;
        if (ifa->ifa_address)
                RTA_PUT(skb, IFA_ADDRESS, 4, &ifa->ifa_address);
        if (ifa->ifa_local)
                RTA_PUT(skb, IFA_LOCAL, 4, &ifa->ifa_local);
        if (ifa->ifa_broadcast)
                RTA_PUT(skb, IFA_BROADCAST, 4, &ifa->ifa_broadcast);
        if (ifa->ifa_anycast)
                RTA_PUT(skb, IFA_ANYCAST, 4, &ifa->ifa_anycast);
        if (ifa->ifa_label[0])
                RTA_PUT(skb, IFA_LABEL, IFNAMSIZ, &ifa->ifa_label);
        nlh->nlmsg_len = skb->tail - b;
        return skb->len;

nlmsg_failure:
rtattr_failure:
        skb_trim(skb, b - skb->data);
        return -1;
}

static int inet_dump_ifaddr(struct sk_buff *skb, struct netlink_callback *cb)
{
        int idx, ip_idx;
        int s_idx, s_ip_idx;
        struct net_device *dev;
        struct in_device *in_dev;
        struct in_ifaddr *ifa;

        s_idx = cb->args[0];
        s_ip_idx = ip_idx = cb->args[1];
        read_lock(&dev_base_lock);
        for (dev=dev_base, idx=0; dev; dev = dev->next, idx++) {
                if (idx < s_idx)
                        continue;
                if (idx > s_idx)
                        s_ip_idx = 0;
                read_lock(&inetdev_lock);
                if ((in_dev = __in_dev_get(dev)) == NULL) {
                        read_unlock(&inetdev_lock);
                        continue;
                }
                read_lock(&in_dev->lock);
                for (ifa = in_dev->ifa_list, ip_idx = 0; ifa;
                     ifa = ifa->ifa_next, ip_idx++) {
                        if (ip_idx < s_ip_idx)
                                continue;
                        if (inet_fill_ifaddr(skb, ifa, NETLINK_CB(cb->skb).pid,
                                             cb->nlh->nlmsg_seq, RTM_NEWADDR) <= 0) {
                                read_unlock(&in_dev->lock);
                                read_unlock(&inetdev_lock);
                                goto done;
                        }
                }
                read_unlock(&in_dev->lock);
                read_unlock(&inetdev_lock);
        }

done:
        read_unlock(&dev_base_lock);
        cb->args[0] = idx;
        cb->args[1] = ip_idx;

        return skb->len;
}

static void rtmsg_ifa(int event, struct in_ifaddr * ifa)
{
        struct sk_buff *skb;
        int size = NLMSG_SPACE(sizeof(struct ifaddrmsg)+128);

        skb = alloc_skb(size, GFP_KERNEL);
        if (!skb) {
                netlink_set_err(rtnl, 0, RTMGRP_IPV4_IFADDR, ENOBUFS);
                return;
        }
        if (inet_fill_ifaddr(skb, ifa, 0, 0, event) < 0) {
                kfree_skb(skb);
                netlink_set_err(rtnl, 0, RTMGRP_IPV4_IFADDR, EINVAL);
                return;
        }
        NETLINK_CB(skb).dst_groups = RTMGRP_IPV4_IFADDR;
        netlink_broadcast(rtnl, skb, 0, RTMGRP_IPV4_IFADDR, GFP_KERNEL);
}


static struct rtnetlink_link inet_rtnetlink_table[RTM_MAX-RTM_BASE+1] =
{
        { NULL,                 NULL,                   },
        { NULL,                 NULL,                   },
        { NULL,                 NULL,                   },
        { NULL,                 NULL,                   },

        { inet_rtm_newaddr,     NULL,                   },
        { inet_rtm_deladdr,     NULL,                   },
        { NULL,                 inet_dump_ifaddr,       },
        { NULL,                 NULL,                   },

        { inet_rtm_newroute,    NULL,                   },
        { inet_rtm_delroute,    NULL,                   },
        { inet_rtm_getroute,    inet_dump_fib,          },
        { NULL,                 NULL,                   },

        { NULL,                 NULL,                   },
        { NULL,                 NULL,                   },
        { NULL,                 NULL,                   },
        { NULL,                 NULL,                   },

#ifdef CONFIG_IP_MULTIPLE_TABLES
        { inet_rtm_newrule,     NULL,                   },
        { inet_rtm_delrule,     NULL,                   },
        { NULL,                 inet_dump_rules,        },
        { NULL,                 NULL,                   },
#else
        { NULL,                 NULL,                   },
        { NULL,                 NULL,                   },
        { NULL,                 NULL,                   },
        { NULL,                 NULL,                   },
#endif
};


#ifdef CONFIG_SYSCTL

void inet_forward_change()
{
        struct net_device *dev;
        int on = ipv4_devconf.forwarding;

        ipv4_devconf.accept_redirects = !on;
        ipv4_devconf_dflt.forwarding = on;

        read_lock(&dev_base_lock);
        for (dev = dev_base; dev; dev = dev->next) {
                struct in_device *in_dev;
                read_lock(&inetdev_lock);
                in_dev = __in_dev_get(dev);
                if (in_dev)
                        in_dev->cnf.forwarding = on;
                read_unlock(&inetdev_lock);
        }
        read_unlock(&dev_base_lock);

        rt_cache_flush(0);
}

static
int devinet_sysctl_forward(ctl_table *ctl, int write, struct file * filp,
                           void *buffer, size_t *lenp)
{
        int *valp = ctl->data;
        int val = *valp;
        int ret;

        ret = proc_dointvec(ctl, write, filp, buffer, lenp);

        if (write && *valp != val) {
                if (valp == &ipv4_devconf.forwarding)
                        inet_forward_change();
                else if (valp != &ipv4_devconf_dflt.forwarding)
                        rt_cache_flush(0);
        }

        return ret;
}

static struct devinet_sysctl_table
{
        struct ctl_table_header *sysctl_header;
        ctl_table devinet_vars[16];
        ctl_table devinet_dev[2];
        ctl_table devinet_conf_dir[2];
        ctl_table devinet_proto_dir[2];
        ctl_table devinet_root_dir[2];
} devinet_sysctl = {
        NULL,
        {{NET_IPV4_CONF_FORWARDING, "forwarding",
         &ipv4_devconf.forwarding, sizeof(int), 0644, NULL,
         &devinet_sysctl_forward},
        {NET_IPV4_CONF_MC_FORWARDING, "mc_forwarding",
         &ipv4_devconf.mc_forwarding, sizeof(int), 0444, NULL,
         &proc_dointvec},
        {NET_IPV4_CONF_ACCEPT_REDIRECTS, "accept_redirects",
         &ipv4_devconf.accept_redirects, sizeof(int), 0644, NULL,
         &proc_dointvec},
        {NET_IPV4_CONF_SECURE_REDIRECTS, "secure_redirects",
         &ipv4_devconf.secure_redirects, sizeof(int), 0644, NULL,
         &proc_dointvec},
        {NET_IPV4_CONF_SHARED_MEDIA, "shared_media",
         &ipv4_devconf.shared_media, sizeof(int), 0644, NULL,
         &proc_dointvec},
        {NET_IPV4_CONF_RP_FILTER, "rp_filter",
         &ipv4_devconf.rp_filter, sizeof(int), 0644, NULL,
         &proc_dointvec},
        {NET_IPV4_CONF_SEND_REDIRECTS, "send_redirects",
         &ipv4_devconf.send_redirects, sizeof(int), 0644, NULL,
         &proc_dointvec},
        {NET_IPV4_CONF_ACCEPT_SOURCE_ROUTE, "accept_source_route",
         &ipv4_devconf.accept_source_route, sizeof(int), 0644, NULL,
         &proc_dointvec},
        {NET_IPV4_CONF_PROXY_ARP, "proxy_arp",
         &ipv4_devconf.proxy_arp, sizeof(int), 0644, NULL,
         &proc_dointvec},
        {NET_IPV4_CONF_MEDIUM_ID, "medium_id",
         &ipv4_devconf.medium_id, sizeof(int), 0644, NULL,
         &proc_dointvec},
        {NET_IPV4_CONF_BOOTP_RELAY, "bootp_relay",
         &ipv4_devconf.bootp_relay, sizeof(int), 0644, NULL,
         &proc_dointvec},
        {NET_IPV4_CONF_LOG_MARTIANS, "log_martians",
         &ipv4_devconf.log_martians, sizeof(int), 0644, NULL,
         &proc_dointvec},
        {NET_IPV4_CONF_TAG, "tag",
         &ipv4_devconf.tag, sizeof(int), 0644, NULL,
         &proc_dointvec},
        {NET_IPV4_CONF_ARPFILTER, "arp_filter",
         &ipv4_devconf.arp_filter, sizeof(int), 0644, NULL,
         &proc_dointvec},
        {NET_IPV4_CONF_LOOP, "loop",
         &ipv4_devconf.loop, sizeof(int), 0644, NULL,
         &proc_dointvec},
         {0}},

        {{NET_PROTO_CONF_ALL, "all", NULL, 0, 0555, devinet_sysctl.devinet_vars},{0}},
        {{NET_IPV4_CONF, "conf", NULL, 0, 0555, devinet_sysctl.devinet_dev},{0}},
        {{NET_IPV4, "ipv4", NULL, 0, 0555, devinet_sysctl.devinet_conf_dir},{0}},
        {{CTL_NET, "net", NULL, 0, 0555, devinet_sysctl.devinet_proto_dir},{0}}
};

static void devinet_sysctl_register(struct in_device *in_dev, struct ipv4_devconf *p)
{
        int i;
        struct net_device *dev = in_dev ? in_dev->dev : NULL;
        struct devinet_sysctl_table *t;

        t = kmalloc(sizeof(*t), GFP_KERNEL);
        if (t == NULL)
                return;
        memcpy(t, &devinet_sysctl, sizeof(*t));
        for (i=0; i<sizeof(t->devinet_vars)/sizeof(t->devinet_vars[0])-1; i++) {
                t->devinet_vars[i].data += (char*)p - (char*)&ipv4_devconf;
                t->devinet_vars[i].de = NULL;
        }
        if (dev) {
                t->devinet_dev[0].procname = dev->name;
                t->devinet_dev[0].ctl_name = dev->ifindex;
        } else {
                t->devinet_dev[0].procname = "default";
                t->devinet_dev[0].ctl_name = NET_PROTO_CONF_DEFAULT;
        }
        t->devinet_dev[0].child = t->devinet_vars;
        t->devinet_dev[0].de = NULL;
        t->devinet_conf_dir[0].child = t->devinet_dev;
        t->devinet_conf_dir[0].de = NULL;
        t->devinet_proto_dir[0].child = t->devinet_conf_dir;
        t->devinet_proto_dir[0].de = NULL;
        t->devinet_root_dir[0].child = t->devinet_proto_dir;
        t->devinet_root_dir[0].de = NULL;

        t->sysctl_header = register_sysctl_table(t->devinet_root_dir, 0);
        if (t->sysctl_header == NULL)
                kfree(t);
        else
                p->sysctl = t;
}

static void devinet_sysctl_unregister(struct ipv4_devconf *p)
{
        if (p->sysctl) {
                struct devinet_sysctl_table *t = p->sysctl;
                p->sysctl = NULL;
                unregister_sysctl_table(t->sysctl_header);
                kfree(t);
        }
}
#endif

void __init devinet_init(void)
{
        register_gifconf(PF_INET, inet_gifconf);
        register_netdevice_notifier(&ip_netdev_notifier);
        rtnetlink_links[PF_INET] = inet_rtnetlink_table;
#ifdef CONFIG_SYSCTL
        devinet_sysctl.sysctl_header =
                register_sysctl_table(devinet_sysctl.devinet_root_dir, 0);
        devinet_sysctl_register(NULL, &ipv4_devconf_dflt);
#endif
}

---