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linux/net/ipv4/fib_frontend.c
Robert Olsson 246955fe4c [NETLINK]: fib_lookup() via netlink 
Below is a more generic patch to do fib_lookup via netlink. For others 
we should say that we discussed this as a way to verify route selection.
It's also possible there are others uses for this.

In short the fist half of struct fib_result_nl is filled in by caller 
and netlink call fills in the other half and returns it.

In case anyone is interested there is a corresponding user app to compare 
the full routing table this was used to test implementation of the LC-trie. 

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-06-20 13:36:39 -07:00

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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 <linux/module.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/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/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 *ip_fib_local_table;
struct fib_table *ip_fib_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 */
static 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 += ip_fib_main_table->tb_flush(ip_fib_main_table);
flushed += ip_fib_local_table->tb_flush(ip_fib_local_table);
#endif /* CONFIG_IP_MULTIPLE_TABLES */
if (flushed)
rt_cache_flush(-1);
}
/*
* Find the first device with a given source address.
*/
struct net_device * ip_dev_find(u32 addr)
{
struct flowi fl = { .nl_u = { .ip4_u = { .daddr = addr } } };
struct fib_result res;
struct net_device *dev = NULL;
#ifdef CONFIG_IP_MULTIPLE_TABLES
res.r = NULL;
#endif
if (!ip_fib_local_table ||
ip_fib_local_table->tb_lookup(ip_fib_local_table, &fl, &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 flowi fl = { .nl_u = { .ip4_u = { .daddr = addr } } };
struct fib_result res;
unsigned ret = RTN_BROADCAST;
if (ZERONET(addr) || BADCLASS(addr))
return RTN_BROADCAST;
if (MULTICAST(addr))
return RTN_MULTICAST;
#ifdef CONFIG_IP_MULTIPLE_TABLES
res.r = NULL;
#endif
if (ip_fib_local_table) {
ret = RTN_UNICAST;
if (!ip_fib_local_table->tb_lookup(ip_fib_local_table,
&fl, &res)) {
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 flowi fl = { .nl_u = { .ip4_u =
{ .daddr = src,
.saddr = dst,
.tos = tos } },
.iif = oif };
struct fib_result res;
int no_addr, rpf;
int ret;
no_addr = rpf = 0;
rcu_read_lock();
in_dev = __in_dev_get(dev);
if (in_dev) {
no_addr = in_dev->ifa_list == NULL;
rpf = IN_DEV_RPFILTER(in_dev);
}
rcu_read_unlock();
if (in_dev == NULL)
goto e_inval;
if (fib_lookup(&fl, &res))
goto last_resort;
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;
fl.oif = dev->ifindex;
ret = 0;
if (fib_lookup(&fl, &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 __user *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 nl_fib_lookup(struct fib_result_nl *frn, struct fib_table *tb )
{
struct fib_result res;
struct flowi fl = { .nl_u = { .ip4_u = { .daddr = frn->fl_addr,
.fwmark = frn->fl_fwmark,
.tos = frn->fl_tos,
.scope = frn->fl_scope } } };
if (tb) {
local_bh_disable();
frn->tb_id = tb->tb_id;
frn->err = tb->tb_lookup(tb, &fl, &res);
if (!frn->err) {
frn->prefixlen = res.prefixlen;
frn->nh_sel = res.nh_sel;
frn->type = res.type;
frn->scope = res.scope;
}
local_bh_enable();
}
}
static void nl_fib_input(struct sock *sk, int len)
{
struct sk_buff *skb = NULL;
struct nlmsghdr *nlh = NULL;
struct fib_result_nl *frn;
int err;
u32 pid;
struct fib_table *tb;
skb = skb_recv_datagram(sk, 0, 0, &err);
nlh = (struct nlmsghdr *)skb->data;
frn = (struct fib_result_nl *) NLMSG_DATA(nlh);
tb = fib_get_table(frn->tb_id_in);
nl_fib_lookup(frn, tb);
pid = nlh->nlmsg_pid; /*pid of sending process */
NETLINK_CB(skb).groups = 0; /* not in mcast group */
NETLINK_CB(skb).pid = 0; /* from kernel */
NETLINK_CB(skb).dst_pid = pid;
NETLINK_CB(skb).dst_groups = 0; /* unicast */
netlink_unicast(sk, skb, pid, MSG_DONTWAIT);
}
static void nl_fib_lookup_init(void)
{
netlink_kernel_create(NETLINK_FIB_LOOKUP, nl_fib_input);
}
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;
}
static struct notifier_block fib_inetaddr_notifier = {
.notifier_call =fib_inetaddr_event,
};
static struct notifier_block fib_netdev_notifier = {
.notifier_call =fib_netdev_event,
};
void __init ip_fib_init(void)
{
#ifndef CONFIG_IP_MULTIPLE_TABLES
ip_fib_local_table = fib_hash_init(RT_TABLE_LOCAL);
ip_fib_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);
nl_fib_lookup_init();
}
EXPORT_SYMBOL(inet_addr_type);
EXPORT_SYMBOL(ip_dev_find);
EXPORT_SYMBOL(ip_rt_ioctl);
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