dn_fib.c

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/*
 * DECnet       An implementation of the DECnet protocol suite for the LINUX
 *              operating system.  DECnet is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              DECnet Routing Forwarding Information Base (Glue/Info List)
 *
 * Author:      Steve Whitehouse <[e-mail]>
 *
 *
 * Changes:
 *              Alexey Kuznetsov : SMP locking changes
 *              Steve Whitehouse : Rewrote it... Well to be more correct, I
 *                                 copied most of it from the ipv4 fib code.
 *
 */
#include <linux/config.h>
#include <linux/string.h>
#include <linux/net.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/init.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/proc_fs.h>
#include <linux/netdevice.h>
#include <linux/timer.h>
#include <linux/spinlock.h>
#include <asm/atomic.h>
#include <asm/uaccess.h>
#include <net/neighbour.h>
#include <net/dst.h>
#include <net/dn.h>
#include <net/dn_route.h>
#include <net/dn_fib.h>
#include <net/dn_neigh.h>
#include <net/dn_dev.h>


#define for_fib_info() { struct dn_fib_info *fi;\
	for(fi = dn_fib_info_list; fi; fi = fi->fib_next)
#define endfor_fib_info() }

#define for_nexthops(fi) { int nhsel; const struct dn_fib_nh *nh;\
	for(nhsel = 0, nh = (fi)->fib_nh; nhsel < (fi)->fib_nhs; nh++, nhsel++)

#define change_nexthops(fi) { int nhsel; struct dn_fib_nh *nh;\
	for(nhsel = 0, nh = (struct dn_fib_nh *)((fi)->fib_nh); nhsel < (fi)->fib_nhs; nh++, nhsel++)

#define endfor_nexthops(fi) }

#ifdef CONFIG_RTNETLINK
extern int dn_cache_dump(struct sk_buff *skb, struct netlink_callback *cb);
#endif /* CONFIG_RTNETLINK */


static struct dn_fib_info *dn_fib_info_list = NULL;
static rwlock_t dn_fib_info_lock = RW_LOCK_UNLOCKED;
int dn_fib_info_cnt;

static struct
{
	int error;
	u8 scope;
} dn_fib_props[RTA_MAX+1] = {
	{ 0, RT_SCOPE_NOWHERE },		/* RTN_UNSPEC */
	{ 0, RT_SCOPE_UNIVERSE },		/* RTN_UNICAST */
	{ 0, RT_SCOPE_HOST },			/* RTN_LOCAL */
	{ -EINVAL, RT_SCOPE_NOWHERE },		/* RTN_BROADCAST */
	{ -EINVAL, RT_SCOPE_NOWHERE },		/* RTN_ANYCAST */
	{ -EINVAL, RT_SCOPE_NOWHERE },		/* RTN_MULTICAST */
	{ -EINVAL, RT_SCOPE_UNIVERSE },		/* RTN_BLACKHOLE */
	{ -EHOSTUNREACH, RT_SCOPE_UNIVERSE },	/* RTN_UNREACHABLE */
	{ -EACCES, RT_SCOPE_UNIVERSE },		/* RTN_PROHIBIT */
	{ -EAGAIN, RT_SCOPE_UNIVERSE },		/* RTN_THROW */
	{ -EINVAL, RT_SCOPE_NOWHERE },		/* RTN_NAT */
	{ -EINVAL, RT_SCOPE_NOWHERE }		/* RTN_XRESOLVE */
};

void dn_fib_free_info(struct dn_fib_info *fi)
{
	if (fi->fib_dead == 0) {
		printk(KERN_DEBUG "DECnet: BUG! Attempt to free alive dn_fib_info\n");
		return;
	}

	change_nexthops(fi) {
		if (nh->nh_dev)
			dev_put(nh->nh_dev);
		nh->nh_dev = NULL;
	} endfor_nexthops(fi);
	dn_fib_info_cnt--;
	kfree(fi);
}

void dn_fib_release_info(struct dn_fib_info *fi)
{
	write_lock(&dn_fib_info_lock);
	if (fi && --fi->fib_treeref == 0) {
		if (fi->fib_next)
			fi->fib_next->fib_prev = fi->fib_prev;
		if (fi->fib_prev)
			fi->fib_prev->fib_next = fi->fib_next;
		if (fi == dn_fib_info_list)
			dn_fib_info_list = fi->fib_next;
		fi->fib_dead = 1;
		dn_fib_info_put(fi);
	}
	write_unlock(&dn_fib_info_lock);
}

static __inline__ int dn_fib_nh_comp(const struct dn_fib_info *fi, const struct dn_fib_info *ofi)
{
	const struct dn_fib_nh *onh = ofi->fib_nh;

	for_nexthops(fi) {
		if (nh->nh_oif != onh->nh_oif ||
			nh->nh_gw != onh->nh_gw ||
			nh->nh_scope != onh->nh_scope ||
			nh->nh_weight != onh->nh_weight ||
			((nh->nh_flags^onh->nh_flags)&~RTNH_F_DEAD))
				return -1;
		onh++;
	} endfor_nexthops(fi);
	return 0;
}

static __inline__ struct dn_fib_info *dn_fib_find_info(const struct dn_fib_info *nfi)
{
	for_fib_info() {
		if (fi->fib_nhs != nfi->fib_nhs)
			continue;
		if (nfi->fib_protocol == fi->fib_protocol &&
			nfi->fib_prefsrc == fi->fib_prefsrc &&
			nfi->fib_priority == fi->fib_priority &&
			((nfi->fib_flags^fi->fib_flags)&~RTNH_F_DEAD) == 0 &&
			(nfi->fib_nhs == 0 || dn_fib_nh_comp(fi, nfi) == 0))
				return fi;
	} endfor_fib_info();
	return NULL;
}

u16 dn_fib_get_attr16(struct rtattr *attr, int attrlen, int type)
{
	while(RTA_OK(attr,attrlen)) {
		if (attr->rta_type == type)
			return *(u16*)RTA_DATA(attr);
		attr = RTA_NEXT(attr, attrlen);
	}

	return 0;
}

static int dn_fib_count_nhs(struct rtattr *rta)
{
	int nhs = 0;
	struct rtnexthop *nhp = RTA_DATA(rta);
	int nhlen = RTA_PAYLOAD(rta);

	while(nhlen >= (int)sizeof(struct rtnexthop)) {
		if ((nhlen -= nhp->rtnh_len) < 0)
			return 0;
		nhs++;
		nhp = RTNH_NEXT(nhp);
	}

	return nhs;
}

static int dn_fib_get_nhs(struct dn_fib_info *fi, const struct rtattr *rta, const struct rtmsg *r)
{
	struct rtnexthop *nhp = RTA_DATA(rta);
	int nhlen = RTA_PAYLOAD(rta);

	change_nexthops(fi) {
		int attrlen = nhlen - sizeof(struct rtnexthop);
		if (attrlen < 0 || (nhlen -= nhp->rtnh_len) < 0)
			return -EINVAL;

		nh->nh_flags  = (r->rtm_flags&~0xFF) | nhp->rtnh_flags;
		nh->nh_oif    = nhp->rtnh_ifindex;
		nh->nh_weight = nhp->rtnh_hops + 1;

		if (attrlen) {
			nh->nh_gw = dn_fib_get_attr16(RTNH_DATA(nhp), attrlen, RTA_GATEWAY);
		}
		nhp = RTNH_NEXT(nhp);
	} endfor_nexthops(fi);

	return 0;
}


static int dn_fib_check_nh(const struct rtmsg *r, struct dn_fib_info *fi, struct dn_fib_nh *nh)
{
	int err;

	if (nh->nh_gw) {
		struct dn_fib_key key;
		struct dn_fib_res res;

		if (nh->nh_flags&RTNH_F_ONLINK) {
			struct net_device *dev;

			if (r->rtm_scope >= RT_SCOPE_LINK)
				return -EINVAL;
			if ((dev = __dev_get_by_index(nh->nh_oif)) == NULL)
				return -ENODEV;
			if (!(dev->flags&IFF_UP))
				return -ENETDOWN;
			nh->nh_dev = dev;
			atomic_inc(&dev->refcnt);
			nh->nh_scope = RT_SCOPE_LINK;
			return 0;
		}

		memset(&key, 0, sizeof(key));
		key.dst = nh->nh_gw;
		key.oif = nh->nh_oif;
		key.scope = r->rtm_scope + 1;

		if (key.scope < RT_SCOPE_LINK)
			key.scope = RT_SCOPE_LINK;

		if ((err = dn_fib_lookup(&key, &res)) != 0)
			return err;

		nh->nh_scope = res.scope;
		nh->nh_oif = DN_FIB_RES_OIF(res);
		nh->nh_dev = DN_FIB_RES_DEV(res);
		if (nh->nh_dev)
			atomic_inc(&nh->nh_dev->refcnt);
		dn_fib_res_put(&res);
	} else {
		struct net_device *dev;

		if (nh->nh_flags&(RTNH_F_PERVASIVE|RTNH_F_ONLINK))
			return -EINVAL;

		dev = __dev_get_by_index(nh->nh_oif);
		if (dev == NULL || dev->dn_ptr == NULL)
			return -ENODEV;
		if (!(dev->flags&IFF_UP))
			return -ENETDOWN;
		nh->nh_dev = dev;
		atomic_inc(&nh->nh_dev->refcnt);
		nh->nh_scope = RT_SCOPE_HOST;
	}

	return 0;
}


struct dn_fib_info *dn_fib_create_info(const struct rtmsg *r, struct dn_kern_rta *rta, const struct nlmsghdr *nlh, int *errp)
{
	int err;
	struct dn_fib_info *fi = NULL;
	struct dn_fib_info *ofi;
	int nhs = 1;

	if (dn_fib_props[r->rtm_type].scope > r->rtm_scope)
		goto err_inval;

	if (rta->rta_mp) {
		nhs = dn_fib_count_nhs(rta->rta_mp);
		if (nhs == 0)
			goto err_inval;
	}

	fi = kmalloc(sizeof(*fi)+nhs*sizeof(struct dn_fib_nh), GFP_KERNEL);
	err = -ENOBUFS;
	if (fi == NULL)
		goto failure;
	memset(fi, 0, sizeof(*fi)+nhs*sizeof(struct dn_fib_nh));

	fi->fib_protocol = r->rtm_protocol;
	fi->fib_nhs = nhs;
	fi->fib_flags = r->rtm_flags;
	if (rta->rta_priority)
		fi->fib_priority = *rta->rta_priority;
	if (rta->rta_prefsrc)
		memcpy(&fi->fib_prefsrc, rta->rta_prefsrc, 2);

	if (rta->rta_mp) {
		if ((err = dn_fib_get_nhs(fi, rta->rta_mp, r)) != 0)
			goto failure;
		if (rta->rta_oif && fi->fib_nh->nh_oif != *rta->rta_oif)
			goto err_inval;
		if (rta->rta_gw && memcmp(&fi->fib_nh->nh_gw, rta->rta_gw, 2))
			goto err_inval;
	} else {
		struct dn_fib_nh *nh = fi->fib_nh;
		if (rta->rta_oif)
			nh->nh_oif = *rta->rta_oif;
		if (rta->rta_gw)
			memcpy(&nh->nh_gw, rta->rta_gw, 2);
		nh->nh_flags = r->rtm_flags;
		nh->nh_weight = 1;
	}

	if (dn_fib_props[r->rtm_type].error) {
		if (rta->rta_gw || rta->rta_oif || rta->rta_mp)
			goto err_inval;
		goto link_it;
	}

	if (r->rtm_scope > RT_SCOPE_HOST)
		goto err_inval;

	if (r->rtm_scope == RT_SCOPE_HOST) {
		struct dn_fib_nh *nh = fi->fib_nh;

		/* Local address is added */
		if (nhs != 1 || nh->nh_gw)
			goto err_inval;
		nh->nh_scope = RT_SCOPE_NOWHERE;
		nh->nh_dev = dev_get_by_index(fi->fib_nh->nh_oif);
		err = -ENODEV;
		if (nh->nh_dev == NULL)
			goto failure;
	} else {
		change_nexthops(fi) {
			if ((err = dn_fib_check_nh(r, fi, nh)) != 0)
				goto failure;
		} endfor_nexthops(fi)
	}

#if I_GET_AROUND_TO_FIXING_PREFSRC
	if (fi->fib_prefsrc) {
		if (r->rtm_type != RTN_LOCAL || rta->rta_dst == NULL ||
		    memcmp(&fi->fib_prefsrc, rta->rta_dst, 2))
			if (dn_addr_type(fi->fib_prefsrc) != RTN_LOCAL)
				goto err_inval;
	}
#endif