kernel-ark/net/ipv4/fib_frontend.c
Herbert Xu e5ed639913 [IPV4]: Replace __in_dev_get with __in_dev_get_rcu/rtnl
The following patch renames __in_dev_get() to __in_dev_get_rtnl() and
introduces __in_dev_get_rcu() to cover the second case.

1) RCU with refcnt should use in_dev_get().
2) RCU without refcnt should use __in_dev_get_rcu().
3) All others must hold RTNL and use __in_dev_get_rtnl().

There is one exception in net/ipv4/route.c which is in fact a pre-existing
race condition.  I've marked it as such so that we remember to fix it.

This patch is based on suggestions and prior work by Suzanne Wood and
Paul McKenney.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-10-03 14:35:55 -07:00

665 lines
15 KiB
C

/*
* 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_rcu(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).pid = 0; /* from kernel */
NETLINK_CB(skb).dst_pid = pid;
NETLINK_CB(skb).dst_group = 0; /* unicast */
netlink_unicast(sk, skb, pid, MSG_DONTWAIT);
}
static void nl_fib_lookup_init(void)
{
netlink_kernel_create(NETLINK_FIB_LOOKUP, 0, nl_fib_input, THIS_MODULE);
}
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_rtnl(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_rt_ioctl);