fib_frontend.c

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/*
 * INET         An implementation of the TCP/IP protocol suite for the LINUX
 *              operating system.  INET is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              IPv4 Forwarding Information Base: FIB frontend.
 *
 * Version:     $Id: fib_frontend.c,v 1.26 2001/10/31 21:55:54 davem Exp $
 *
 * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 *
 *              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.
 */

#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/mm.h>
#include <linux/string.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/errno.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/proc_fs.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/init.h>

#include <net/ip.h>
#include <net/protocol.h>
#include <net/route.h>
#include <net/tcp.h>
#include <net/sock.h>
#include <net/icmp.h>
#include <net/arp.h>
#include <net/ip_fib.h>

#define FFprint(a...) printk(KERN_DEBUG a)

#ifndef CONFIG_IP_MULTIPLE_TABLES

#define RT_TABLE_MIN RT_TABLE_MAIN

struct fib_table *local_table;
struct fib_table *main_table;

#else

#define RT_TABLE_MIN 1

struct fib_table *fib_tables[RT_TABLE_MAX+1];

struct fib_table *__fib_new_table(int id)
{
        struct fib_table *tb;

        tb = fib_hash_init(id);
        if (!tb)
                return NULL;
        fib_tables[id] = tb;
        return tb;
}


#endif /* CONFIG_IP_MULTIPLE_TABLES */


void fib_flush(void)
{
        int flushed = 0;
#ifdef CONFIG_IP_MULTIPLE_TABLES
        struct fib_table *tb;
        int id;

        for (id = RT_TABLE_MAX; id>0; id--) {
                if ((tb = fib_get_table(id))==NULL)
                        continue;
                flushed += tb->tb_flush(tb);
        }
#else /* CONFIG_IP_MULTIPLE_TABLES */
        flushed += main_table->tb_flush(main_table);
        flushed += local_table->tb_flush(local_table);
#endif /* CONFIG_IP_MULTIPLE_TABLES */

        if (flushed)
                rt_cache_flush(-1);
}


#ifdef CONFIG_PROC_FS

/* 
 *      Called from the PROCfs module. This outputs /proc/net/route.
 *
 *      It always works in backward compatibility mode.
 *      The format of the file is not supposed to be changed.
 */
 
static int
fib_get_procinfo(char *buffer, char **start, off_t offset, int length)
{
        int first = offset/128;
        char *ptr = buffer;
        int count = (length+127)/128;
        int len;

        *start = buffer + offset%128;
        
        if (--first < 0) {
                sprintf(buffer, "%-127s\n", "Iface\tDestination\tGateway \tFlags\tRefCnt\tUse\tMetric\tMask\t\tMTU\tWindow\tIRTT");
                --count;
                ptr += 128;
                first = 0;
        }

        if (main_table && count > 0) {
                int n = main_table->tb_get_info(main_table, ptr, first, count);
                count -= n;
                ptr += n*128;
        }
        len = ptr - *start;
        if (len >= length)
                return length;
        if (len >= 0)
                return len;
        return 0;
}

#endif /* CONFIG_PROC_FS */

/*
 *      Find the first device with a given source address.
 */

struct net_device * ip_dev_find(u32 addr)
{
        struct rt_key key;
        struct fib_result res;
        struct net_device *dev = NULL;

        memset(&key, 0, sizeof(key));
        key.dst = addr;
#ifdef CONFIG_IP_MULTIPLE_TABLES
        res.r = NULL;
#endif

        if (!local_table || local_table->tb_lookup(local_table, &key, &res)) {
                return NULL;
        }
        if (res.type != RTN_LOCAL)
                goto out;
        dev = FIB_RES_DEV(res);

        if (dev)
                dev_hold(dev);
out:
        fib_res_put(&res);
        return dev;
}

unsigned inet_addr_type(u32 addr)
{
        struct rt_key           key;
        struct fib_result       res;
        unsigned ret = RTN_BROADCAST;

        if (ZERONET(addr) || BADCLASS(addr))
                return RTN_BROADCAST;
        if (MULTICAST(addr))
                return RTN_MULTICAST;

        memset(&key, 0, sizeof(key));
        key.dst = addr;
#ifdef CONFIG_IP_MULTIPLE_TABLES
        res.r = NULL;
#endif
        
        if (local_table) {
                ret = RTN_UNICAST;
                if (local_table->tb_lookup(local_table, &key, &res) == 0) {
                        ret = res.type;
                        fib_res_put(&res);
                }
        }
        return ret;
}

/* Given (packet source, input interface) and optional (dst, oif, tos):
   - (main) check, that source is valid i.e. not broadcast or our local
     address.
   - figure out what "logical" interface this packet arrived
     and calculate "specific destination" address.
   - check, that packet arrived from expected physical interface.
 */

int fib_validate_source(u32 src, u32 dst, u8 tos, int oif,
                        struct net_device *dev, u32 *spec_dst, u32 *itag)
{
        struct in_device *in_dev;
        struct rt_key key;
        struct fib_result res;
        int no_addr, rpf, loop;
        int ret;

        key.dst = src;
        key.src = dst;
        key.tos = tos;
        key.oif = 0;
        key.iif = oif;
        key.scope = RT_SCOPE_UNIVERSE;

        no_addr = rpf = loop = 0;
        read_lock(&inetdev_lock);
        in_dev = __in_dev_get(dev);
        if (in_dev) {
                no_addr = in_dev->ifa_list == NULL;
                rpf = IN_DEV_RPFILTER(in_dev);
                loop = IN_DEV_LOOP(in_dev);
        }
        read_unlock(&inetdev_lock);

        if (in_dev == NULL)
                goto e_inval;

        if (fib_lookup(&key, &res))
                goto last_resort;
        if (loop && res.type == RTN_LOCAL) {
                *spec_dst = FIB_RES_PREFSRC(res);
                fib_res_put(&res);
                return 0;
        }
        if (res.type != RTN_UNICAST)
                goto e_inval_res;
        *spec_dst = FIB_RES_PREFSRC(res);
        fib_combine_itag(itag, &res);
#ifdef CONFIG_IP_ROUTE_MULTIPATH
        if (FIB_RES_DEV(res) == dev || res.fi->fib_nhs > 1)
#else
        if (FIB_RES_DEV(res) == dev)
#endif
        {
                ret = FIB_RES_NH(res).nh_scope >= RT_SCOPE_HOST;
                fib_res_put(&res);
                return ret;
        }
        fib_res_put(&res);
        if (no_addr)
                goto last_resort;
        if (rpf)
                goto e_inval;
        key.oif = dev->ifindex;

        ret = 0;
        if (fib_lookup(&key, &res) == 0) {
                if (res.type == RTN_UNICAST) {
                        *spec_dst = FIB_RES_PREFSRC(res);
                        ret = FIB_RES_NH(res).nh_scope >= RT_SCOPE_HOST;
                }
                fib_res_put(&res);
        }
        return ret;

last_resort:
        if (rpf)
                goto e_inval;
        *spec_dst = inet_select_addr(dev, 0, RT_SCOPE_UNIVERSE);
        *itag = 0;
        return 0;

e_inval_res:
        fib_res_put(&res);
e_inval:
        return -EINVAL;
}

#ifndef CONFIG_IP_NOSIOCRT

/*
 *      Handle IP routing ioctl calls. These are used to manipulate the routing tables
 */
 
int ip_rt_ioctl(unsigned int cmd, void *arg)
{
        int err;
        struct kern_rta rta;
        struct rtentry  r;
        struct {
                struct nlmsghdr nlh;
                struct rtmsg    rtm;
        } req;

        switch (cmd) {
        case SIOCADDRT:         /* Add a route */
        case SIOCDELRT:         /* Delete a route */
                if (!capable(CAP_NET_ADMIN))
                        return -EPERM;
                if (copy_from_user(&r, arg, sizeof(struct rtentry)))
                        return -EFAULT;
                rtnl_lock();
                err = fib_convert_rtentry(cmd, &req.nlh, &req.rtm, &rta, &r);
                if (err == 0) {
                        if (cmd == SIOCDELRT) {
                                struct fib_table *tb = fib_get_table(req.rtm.rtm_table);
                                err = -ESRCH;
                                if (tb)
                                        err = tb->tb_delete(tb, &req.rtm, &rta, &req.nlh, NULL);
                        } else {
                                struct fib_table *tb = fib_new_table(req.rtm.rtm_table);
                                err = -ENOBUFS;
                                if (tb)
                                        err = tb->tb_insert(tb, &req.rtm, &rta, &req.nlh, NULL);
                        }
                        if (rta.rta_mx)
                                kfree(rta.rta_mx);
                }
                rtnl_unlock();
                return err;
        }
        return -EINVAL;
}

#else

int ip_rt_ioctl(unsigned int cmd, void *arg)
{
        return -EINVAL;
}

#endif

static int inet_check_attr(struct rtmsg *r, struct rtattr **rta)
{
        int i;

        for (i=1; i<=RTA_MAX; i++) {
                struct rtattr *attr = rta[i-1];
                if (attr) {
                        if (RTA_PAYLOAD(attr) < 4)
                                return -EINVAL;
                        if (i != RTA_MULTIPATH && i != RTA_METRICS)
                                rta[i-1] = (struct rtattr*)RTA_DATA(attr);
                }
        }
        return 0;
}

int inet_rtm_delroute(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
{
        struct fib_table * tb;
        struct rtattr **rta = arg;
        struct rtmsg *r = NLMSG_DATA(nlh);

        if (inet_check_attr(r, rta))
                return -EINVAL;

        tb = fib_get_table(r->rtm_table);
        if (tb)
                return tb->tb_delete(tb, r, (struct kern_rta*)rta, nlh, &NETLINK_CB(skb));
        return -ESRCH;
}

int inet_rtm_newroute(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
{
        struct fib_table * tb;
        struct rtattr **rta = arg;
        struct rtmsg *r = NLMSG_DATA(nlh);

        if (inet_check_attr(r, rta))
                return -EINVAL;

        tb = fib_new_table(r->rtm_table);
        if (tb)
                return tb->tb_insert(tb, r, (struct kern_rta*)rta, nlh, &NETLINK_CB(skb));
        return -ENOBUFS;
}

int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
{
        int t;
        int s_t;
        struct fib_table *tb;

        if (NLMSG_PAYLOAD(cb->nlh, 0) >= sizeof(struct rtmsg) &&
            ((struct rtmsg*)NLMSG_DATA(cb->nlh))->rtm_flags&RTM_F_CLONED)
                return ip_rt_dump(skb, cb);

        s_t = cb->args[0];
        if (s_t == 0)
                s_t = cb->args[0] = RT_TABLE_MIN;

        for (t=s_t; t<=RT_TABLE_MAX; t++) {
                if (t < s_t) continue;
                if (t > s_t)
                        memset(&cb->args[1], 0, sizeof(cb->args)-sizeof(cb->args[0]));
                if ((tb = fib_get_table(t))==NULL)
                        continue;
                if (tb->tb_dump(tb, skb, cb) < 0) 
                        break;
        }

        cb->args[0] = t;

        return skb->len;
}

/* Prepare and feed intra-kernel routing request.
   Really, it should be netlink message, but :-( netlink
   can be not configured, so that we feed it directly
   to fib engine. It is legal, because all events occur
   only when netlink is already locked.
 */

static void fib_magic(int cmd, int type, u32 dst, int dst_len, struct in_ifaddr *ifa)
{
        struct fib_table * tb;
        struct {
                struct nlmsghdr nlh;
                struct rtmsg    rtm;
        } req;
        struct kern_rta rta;

        memset(&req.rtm, 0, sizeof(req.rtm));
        memset(&rta, 0, sizeof(rta));

        if (type == RTN_UNICAST)
                tb = fib_new_table(RT_TABLE_MAIN);
        else
                tb = fib_new_table(RT_TABLE_LOCAL);

        if (tb == NULL)
                return;

        req.nlh.nlmsg_len = sizeof(req);
        req.nlh.nlmsg_type = cmd;
        req.nlh.nlmsg_flags = NLM_F_REQUEST|NLM_F_CREATE|NLM_F_APPEND;
        req.nlh.nlmsg_pid = 0;
        req.nlh.nlmsg_seq = 0;

        req.rtm.rtm_dst_len = dst_len;
        req.rtm.rtm_table = tb->tb_id;
        req.rtm.rtm_protocol = RTPROT_KERNEL;
        req.rtm.rtm_scope = (type != RTN_LOCAL ? RT_SCOPE_LINK : RT_SCOPE_HOST);
        req.rtm.rtm_type = type;

        rta.rta_dst = &dst;
        rta.rta_prefsrc = &ifa->ifa_local;
        rta.rta_oif = &ifa->ifa_dev->dev->ifindex;

        if (cmd == RTM_NEWROUTE)
                tb->tb_insert(tb, &req.rtm, &rta, &req.nlh, NULL);
        else
                tb->tb_delete(tb, &req.rtm, &rta, &req.nlh, NULL);
}

static void fib_add_ifaddr(struct in_ifaddr *ifa)
{
        struct in_device *in_dev = ifa->ifa_dev;
        struct net_device *dev = in_dev->dev;
        struct in_ifaddr *prim = ifa;
        u32 mask = ifa->ifa_mask;
        u32 addr = ifa->ifa_local;
        u32 prefix = ifa->ifa_address&mask;

        if (ifa->ifa_flags&IFA_F_SECONDARY) {
                prim = inet_ifa_byprefix(in_dev, prefix, mask);
                if (prim == NULL) {
                        printk(KERN_DEBUG "fib_add_ifaddr: bug: prim == NULL\n");
                        return;
                }
        }

        fib_magic(RTM_NEWROUTE, RTN_LOCAL, addr, 32, prim);

        if (!(dev->flags&IFF_UP))
                return;

        /* Add broadcast address, if it is explicitly assigned. */
        if (ifa->ifa_broadcast && ifa->ifa_broadcast != 0xFFFFFFFF)
                fib_magic(RTM_NEWROUTE, RTN_BROADCAST, ifa->ifa_broadcast, 32, prim);

        if (!ZERONET(prefix) && !(ifa->ifa_flags&IFA_F_SECONDARY) &&
            (prefix != addr || ifa->ifa_prefixlen < 32)) {
                fib_magic(RTM_NEWROUTE, dev->flags&IFF_LOOPBACK ? RTN_LOCAL :
                          RTN_UNICAST, prefix, ifa->ifa_prefixlen, prim);

                /* Add network specific broadcasts, when it takes a sense */
                if (ifa->ifa_prefixlen < 31) {
                        fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix, 32, prim);
                        fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix|~mask, 32, prim);
                }
        }
}

static void fib_del_ifaddr(struct in_ifaddr *ifa)
{
        struct in_device *in_dev = ifa->ifa_dev;
        struct net_device *dev = in_dev->dev;
        struct in_ifaddr *ifa1;
        struct in_ifaddr *prim = ifa;
        u32 brd = ifa->ifa_address|~ifa->ifa_mask;
        u32 any = ifa->ifa_address&ifa->ifa_mask;
#define LOCAL_OK        1
#define BRD_OK          2
#define BRD0_OK         4
#define BRD1_OK         8
        unsigned ok = 0;

        if (!(ifa->ifa_flags&IFA_F_SECONDARY))
                fib_magic(RTM_DELROUTE, dev->flags&IFF_LOOPBACK ? RTN_LOCAL :
                          RTN_UNICAST, any, ifa->ifa_prefixlen, prim);
        else {
                prim = inet_ifa_byprefix(in_dev, any, ifa->ifa_mask);
                if (prim == NULL) {
                        printk(KERN_DEBUG "fib_del_ifaddr: bug: prim == NULL\n");
                        return;
                }
        }

        /* Deletion is more complicated than add.
           We should take care of not to delete too much :-)

           Scan address list to be sure that addresses are really gone.
         */

        for (ifa1 = in_dev->ifa_list; ifa1; ifa1 = ifa1->ifa_next) {
                if (ifa->ifa_local == ifa1->ifa_local)
                        ok |= LOCAL_OK;
                if (ifa->ifa_broadcast == ifa1->ifa_broadcast)
                        ok |= BRD_OK;
                if (brd == ifa1->ifa_broadcast)
                        ok |= BRD1_OK;
                if (any == ifa1->ifa_broadcast)
                        ok |= BRD0_OK;
        }

        if (!(ok&BRD_OK))
                fib_magic(RTM_DELROUTE, RTN_BROADCAST, ifa->ifa_broadcast, 32, prim);
        if (!(ok&BRD1_OK))
                fib_magic(RTM_DELROUTE, RTN_BROADCAST, brd, 32, prim);
        if (!(ok&BRD0_OK))
                fib_magic(RTM_DELROUTE, RTN_BROADCAST, any, 32, prim);
        if (!(ok&LOCAL_OK)) {
                fib_magic(RTM_DELROUTE, RTN_LOCAL, ifa->ifa_local, 32, prim);

                /* Check, that this local address finally disappeared. */
                if (inet_addr_type(ifa->ifa_local) != RTN_LOCAL) {
                        /* And the last, but not the least thing.
                           We must flush stray FIB entries.

                           First of all, we scan fib_info list searching
                           for stray nexthop entries, then ignite fib_flush.
                        */
                        if (fib_sync_down(ifa->ifa_local, NULL, 0))
                                fib_flush();
                }
        }
#undef LOCAL_OK
#undef BRD_OK
#undef BRD0_OK
#undef BRD1_OK
}

static void fib_disable_ip(struct net_device *dev, int force)
{
        if (fib_sync_down(0, dev, force))
                fib_flush();
        rt_cache_flush(0);
        arp_ifdown(dev);
}

static int fib_inetaddr_event(struct notifier_block *this, unsigned long event, void *ptr)
{
        struct in_ifaddr *ifa = (struct in_ifaddr*)ptr;

        switch (event) {
        case NETDEV_UP:
                fib_add_ifaddr(ifa);
#ifdef CONFIG_IP_ROUTE_MULTIPATH
                fib_sync_up(ifa->ifa_dev->dev);
#endif
                rt_cache_flush(-1);
                break;
        case NETDEV_DOWN:
                fib_del_ifaddr(ifa);
                if (ifa->ifa_dev && ifa->ifa_dev->ifa_list == NULL) {
                        /* Last address was deleted from this interface.
                           Disable IP.
                         */
                        fib_disable_ip(ifa->ifa_dev->dev, 1);
                } else {
                        rt_cache_flush(-1);
                }
                break;
        }
        return NOTIFY_DONE;
}

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

        if (event == NETDEV_UNREGISTER) {
                fib_disable_ip(dev, 2);
                return NOTIFY_DONE;
        }

        if (!in_dev)
                return NOTIFY_DONE;

        switch (event) {
        case NETDEV_UP:
                for_ifa(in_dev) {
                        fib_add_ifaddr(ifa);
                } endfor_ifa(in_dev);
#ifdef CONFIG_IP_ROUTE_MULTIPATH
                fib_sync_up(dev);
#endif
                rt_cache_flush(-1);
                break;
        case NETDEV_DOWN:
                fib_disable_ip(dev, 0);
                break;
        case NETDEV_CHANGEMTU:
        case NETDEV_CHANGE:
                rt_cache_flush(0);
                break;
        }
        return NOTIFY_DONE;
}

struct notifier_block fib_inetaddr_notifier = {
        notifier_call:  fib_inetaddr_event,
};

struct notifier_block fib_netdev_notifier = {
        notifier_call:  fib_netdev_event,
};

void __init ip_fib_init(void)
{
#ifdef CONFIG_PROC_FS
        proc_net_create("route",0,fib_get_procinfo);
#endif          /* CONFIG_PROC_FS */

#ifndef CONFIG_IP_MULTIPLE_TABLES
        local_table = fib_hash_init(RT_TABLE_LOCAL);
        main_table = fib_hash_init(RT_TABLE_MAIN);
#else
        fib_rules_init();
#endif

        register_netdevice_notifier(&fib_netdev_notifier);
        register_inetaddr_notifier(&fib_inetaddr_notifier);
}

---