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32 results

hardware.h

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  • fib_semantics.c 31.08 KiB
    /*
     * 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: semantics.
     *
     * 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 <asm/uaccess.h>
    #include <linux/bitops.h>
    #include <linux/types.h>
    #include <linux/kernel.h>
    #include <linux/jiffies.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/inetdevice.h>
    #include <linux/netdevice.h>
    #include <linux/if_arp.h>
    #include <linux/proc_fs.h>
    #include <linux/skbuff.h>
    #include <linux/init.h>
    #include <linux/slab.h>
    
    #include <net/arp.h>
    #include <net/ip.h>
    #include <net/protocol.h>
    #include <net/route.h>
    #include <net/tcp.h>
    #include <net/sock.h>
    #include <net/ip_fib.h>
    #include <net/netlink.h>
    #include <net/nexthop.h>
    
    #include "fib_lookup.h"
    
    static DEFINE_SPINLOCK(fib_info_lock);
    static struct hlist_head *fib_info_hash;
    static struct hlist_head *fib_info_laddrhash;
    static unsigned int fib_info_hash_size;
    static unsigned int fib_info_cnt;
    
    #define DEVINDEX_HASHBITS 8
    #define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)
    static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
    
    #ifdef CONFIG_IP_ROUTE_MULTIPATH
    
    static DEFINE_SPINLOCK(fib_multipath_lock);
    
    #define for_nexthops(fi) {						\
    	int nhsel; const struct fib_nh *nh;				\
    	for (nhsel = 0, nh = (fi)->fib_nh;				\
    	     nhsel < (fi)->fib_nhs;					\
    	     nh++, nhsel++)
    
    #define change_nexthops(fi) {						\
    	int nhsel; struct fib_nh *nexthop_nh;				\
    	for (nhsel = 0,	nexthop_nh = (struct fib_nh *)((fi)->fib_nh);	\
    	     nhsel < (fi)->fib_nhs;					\
    	     nexthop_nh++, nhsel++)
    
    #else /* CONFIG_IP_ROUTE_MULTIPATH */
    
    /* Hope, that gcc will optimize it to get rid of dummy loop */
    
    #define for_nexthops(fi) {						\
    	int nhsel; const struct fib_nh *nh = (fi)->fib_nh;		\
    	for (nhsel = 0; nhsel < 1; nhsel++)
    
    #define change_nexthops(fi) {						\
    	int nhsel;							\
    	struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh);	\
    	for (nhsel = 0; nhsel < 1; nhsel++)
    
    #endif /* CONFIG_IP_ROUTE_MULTIPATH */
    
    #define endfor_nexthops(fi) }
    
    
    const struct fib_prop fib_props[RTN_MAX + 1] = {
    	[RTN_UNSPEC] = {
    		.error	= 0,
    		.scope	= RT_SCOPE_NOWHERE,
    	},
    	[RTN_UNICAST] = {
    		.error	= 0,
    		.scope	= RT_SCOPE_UNIVERSE,
    	},
    	[RTN_LOCAL] = {
    		.error	= 0,
    		.scope	= RT_SCOPE_HOST,
    	},
    	[RTN_BROADCAST] = {
    		.error	= 0,
    		.scope	= RT_SCOPE_LINK,
    	},
    	[RTN_ANYCAST] = {
    		.error	= 0,
    		.scope	= RT_SCOPE_LINK,
    	},
    	[RTN_MULTICAST] = {
    		.error	= 0,
    		.scope	= RT_SCOPE_UNIVERSE,
    	},
    	[RTN_BLACKHOLE] = {
    		.error	= -EINVAL,
    		.scope	= RT_SCOPE_UNIVERSE,
    	},
    	[RTN_UNREACHABLE] = {
    		.error	= -EHOSTUNREACH,
    		.scope	= RT_SCOPE_UNIVERSE,
    	},
    	[RTN_PROHIBIT] = {
    		.error	= -EACCES,
    		.scope	= RT_SCOPE_UNIVERSE,
    	},
    	[RTN_THROW] = {
    		.error	= -EAGAIN,
    		.scope	= RT_SCOPE_UNIVERSE,
    	},
    	[RTN_NAT] = {
    		.error	= -EINVAL,
    		.scope	= RT_SCOPE_NOWHERE,
    	},
    	[RTN_XRESOLVE] = {
    		.error	= -EINVAL,
    		.scope	= RT_SCOPE_NOWHERE,
    	},
    };
    
    static void rt_fibinfo_free(struct rtable __rcu **rtp)
    {
    	struct rtable *rt = rcu_dereference_protected(*rtp, 1);
    
    	if (!rt)
    		return;
    
    	/* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
    	 * because we waited an RCU grace period before calling
    	 * free_fib_info_rcu()
    	 */
    
    	dst_free(&rt->dst);
    }
    
    static void free_nh_exceptions(struct fib_nh *nh)
    {
    	struct fnhe_hash_bucket *hash = nh->nh_exceptions;
    	int i;
    
    	for (i = 0; i < FNHE_HASH_SIZE; i++) {
    		struct fib_nh_exception *fnhe;
    
    		fnhe = rcu_dereference_protected(hash[i].chain, 1);
    		while (fnhe) {
    			struct fib_nh_exception *next;
    			
    			next = rcu_dereference_protected(fnhe->fnhe_next, 1);
    
    			rt_fibinfo_free(&fnhe->fnhe_rth);
    
    			kfree(fnhe);
    
    			fnhe = next;
    		}
    	}
    	kfree(hash);
    }
    
    static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
    {
    	int cpu;
    
    	if (!rtp)
    		return;
    
    	for_each_possible_cpu(cpu) {
    		struct rtable *rt;
    
    		rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
    		if (rt)
    			dst_free(&rt->dst);
    	}
    	free_percpu(rtp);
    }
    
    /* Release a nexthop info record */
    static void free_fib_info_rcu(struct rcu_head *head)
    {
    	struct fib_info *fi = container_of(head, struct fib_info, rcu);
    
    	change_nexthops(fi) {
    		if (nexthop_nh->nh_dev)
    			dev_put(nexthop_nh->nh_dev);
    		if (nexthop_nh->nh_exceptions)
    			free_nh_exceptions(nexthop_nh);
    		rt_fibinfo_free_cpus(nexthop_nh->nh_pcpu_rth_output);
    		rt_fibinfo_free(&nexthop_nh->nh_rth_input);
    	} endfor_nexthops(fi);
    
    	release_net(fi->fib_net);
    	if (fi->fib_metrics != (u32 *) dst_default_metrics)
    		kfree(fi->fib_metrics);
    	kfree(fi);
    }
    
    void free_fib_info(struct fib_info *fi)
    {
    	if (fi->fib_dead == 0) {
    		pr_warn("Freeing alive fib_info %p\n", fi);
    		return;
    	}
    	fib_info_cnt--;
    #ifdef CONFIG_IP_ROUTE_CLASSID
    	change_nexthops(fi) {
    		if (nexthop_nh->nh_tclassid)
    			fi->fib_net->ipv4.fib_num_tclassid_users--;
    	} endfor_nexthops(fi);
    #endif
    	call_rcu(&fi->rcu, free_fib_info_rcu);
    }
    
    void fib_release_info(struct fib_info *fi)
    {
    	spin_lock_bh(&fib_info_lock);
    	if (fi && --fi->fib_treeref == 0) {
    		hlist_del(&fi->fib_hash);
    		if (fi->fib_prefsrc)
    			hlist_del(&fi->fib_lhash);
    		change_nexthops(fi) {
    			if (!nexthop_nh->nh_dev)
    				continue;
    			hlist_del(&nexthop_nh->nh_hash);
    		} endfor_nexthops(fi)
    		fi->fib_dead = 1;
    		fib_info_put(fi);
    	}
    	spin_unlock_bh(&fib_info_lock);
    }
    
    static inline int nh_comp(const struct fib_info *fi, const struct fib_info *ofi)
    {
    	const struct 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 ||
    #ifdef CONFIG_IP_ROUTE_MULTIPATH
    		    nh->nh_weight != onh->nh_weight ||
    #endif
    #ifdef CONFIG_IP_ROUTE_CLASSID
    		    nh->nh_tclassid != onh->nh_tclassid ||
    #endif
    		    ((nh->nh_flags ^ onh->nh_flags) & ~RTNH_F_DEAD))
    			return -1;
    		onh++;
    	} endfor_nexthops(fi);
    	return 0;
    }
    
    static inline unsigned int fib_devindex_hashfn(unsigned int val)
    {
    	unsigned int mask = DEVINDEX_HASHSIZE - 1;
    
    	return (val ^
    		(val >> DEVINDEX_HASHBITS) ^
    		(val >> (DEVINDEX_HASHBITS * 2))) & mask;
    }
    
    static inline unsigned int fib_info_hashfn(const struct fib_info *fi)
    {
    	unsigned int mask = (fib_info_hash_size - 1);
    	unsigned int val = fi->fib_nhs;
    
    	val ^= (fi->fib_protocol << 8) | fi->fib_scope;
    	val ^= (__force u32)fi->fib_prefsrc;
    	val ^= fi->fib_priority;
    	for_nexthops(fi) {
    		val ^= fib_devindex_hashfn(nh->nh_oif);
    	} endfor_nexthops(fi)
    
    	return (val ^ (val >> 7) ^ (val >> 12)) & mask;
    }
    
    static struct fib_info *fib_find_info(const struct fib_info *nfi)
    {
    	struct hlist_head *head;
    	struct hlist_node *node;
    	struct fib_info *fi;
    	unsigned int hash;
    
    	hash = fib_info_hashfn(nfi);
    	head = &fib_info_hash[hash];
    
    	hlist_for_each_entry(fi, node, head, fib_hash) {
    		if (!net_eq(fi->fib_net, nfi->fib_net))
    			continue;
    		if (fi->fib_nhs != nfi->fib_nhs)
    			continue;
    		if (nfi->fib_protocol == fi->fib_protocol &&
    		    nfi->fib_scope == fi->fib_scope &&
    		    nfi->fib_prefsrc == fi->fib_prefsrc &&
    		    nfi->fib_priority == fi->fib_priority &&
    		    nfi->fib_type == fi->fib_type &&
    		    memcmp(nfi->fib_metrics, fi->fib_metrics,
    			   sizeof(u32) * RTAX_MAX) == 0 &&
    		    ((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_F_DEAD) == 0 &&
    		    (nfi->fib_nhs == 0 || nh_comp(fi, nfi) == 0))
    			return fi;
    	}
    
    	return NULL;
    }
    
    /* Check, that the gateway is already configured.
     * Used only by redirect accept routine.
     */
    int ip_fib_check_default(__be32 gw, struct net_device *dev)
    {
    	struct hlist_head *head;
    	struct hlist_node *node;
    	struct fib_nh *nh;
    	unsigned int hash;
    
    	spin_lock(&fib_info_lock);
    
    	hash = fib_devindex_hashfn(dev->ifindex);
    	head = &fib_info_devhash[hash];
    	hlist_for_each_entry(nh, node, head, nh_hash) {
    		if (nh->nh_dev == dev &&
    		    nh->nh_gw == gw &&
    		    !(nh->nh_flags & RTNH_F_DEAD)) {
    			spin_unlock(&fib_info_lock);
    			return 0;
    		}
    	}
    
    	spin_unlock(&fib_info_lock);
    
    	return -1;
    }
    
    static inline size_t fib_nlmsg_size(struct fib_info *fi)
    {
    	size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
    			 + nla_total_size(4) /* RTA_TABLE */
    			 + nla_total_size(4) /* RTA_DST */
    			 + nla_total_size(4) /* RTA_PRIORITY */
    			 + nla_total_size(4); /* RTA_PREFSRC */
    
    	/* space for nested metrics */
    	payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
    
    	if (fi->fib_nhs) {
    		/* Also handles the special case fib_nhs == 1 */
    
    		/* each nexthop is packed in an attribute */
    		size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
    
    		/* may contain flow and gateway attribute */
    		nhsize += 2 * nla_total_size(4);
    
    		/* all nexthops are packed in a nested attribute */
    		payload += nla_total_size(fi->fib_nhs * nhsize);
    	}
    
    	return payload;
    }
    
    void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
    	       int dst_len, u32 tb_id, struct nl_info *info,
    	       unsigned int nlm_flags)
    {
    	struct sk_buff *skb;
    	u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
    	int err = -ENOBUFS;
    
    	skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
    	if (skb == NULL)
    		goto errout;
    
    	err = fib_dump_info(skb, info->portid, seq, event, tb_id,
    			    fa->fa_type, key, dst_len,
    			    fa->fa_tos, fa->fa_info, nlm_flags);
    	if (err < 0) {
    		/* -EMSGSIZE implies BUG in fib_nlmsg_size() */
    		WARN_ON(err == -EMSGSIZE);
    		kfree_skb(skb);
    		goto errout;
    	}
    	rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
    		    info->nlh, GFP_KERNEL);
    	return;
    errout:
    	if (err < 0)
    		rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
    }
    
    /* Return the first fib alias matching TOS with
     * priority less than or equal to PRIO.
     */
    struct fib_alias *fib_find_alias(struct list_head *fah, u8 tos, u32 prio)
    {
    	if (fah) {
    		struct fib_alias *fa;
    		list_for_each_entry(fa, fah, fa_list) {
    			if (fa->fa_tos > tos)
    				continue;
    			if (fa->fa_info->fib_priority >= prio ||
    			    fa->fa_tos < tos)
    				return fa;
    		}
    	}
    	return NULL;
    }
    
    int fib_detect_death(struct fib_info *fi, int order,
    		     struct fib_info **last_resort, int *last_idx, int dflt)
    {
    	struct neighbour *n;
    	int state = NUD_NONE;
    
    	n = neigh_lookup(&arp_tbl, &fi->fib_nh[0].nh_gw, fi->fib_dev);
    	if (n) {
    		state = n->nud_state;
    		neigh_release(n);
    	}
    	if (state == NUD_REACHABLE)
    		return 0;
    	if ((state & NUD_VALID) && order != dflt)
    		return 0;
    	if ((state & NUD_VALID) ||
    	    (*last_idx < 0 && order > dflt)) {
    		*last_resort = fi;
    		*last_idx = order;
    	}
    	return 1;
    }
    
    #ifdef CONFIG_IP_ROUTE_MULTIPATH
    
    static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining)
    {
    	int nhs = 0;
    
    	while (rtnh_ok(rtnh, remaining)) {
    		nhs++;
    		rtnh = rtnh_next(rtnh, &remaining);
    	}
    
    	/* leftover implies invalid nexthop configuration, discard it */
    	return remaining > 0 ? 0 : nhs;
    }
    
    static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
    		       int remaining, struct fib_config *cfg)
    {
    	change_nexthops(fi) {
    		int attrlen;
    
    		if (!rtnh_ok(rtnh, remaining))
    			return -EINVAL;
    
    		nexthop_nh->nh_flags =
    			(cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
    		nexthop_nh->nh_oif = rtnh->rtnh_ifindex;
    		nexthop_nh->nh_weight = rtnh->rtnh_hops + 1;
    
    		attrlen = rtnh_attrlen(rtnh);
    		if (attrlen > 0) {
    			struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
    
    			nla = nla_find(attrs, attrlen, RTA_GATEWAY);
    			nexthop_nh->nh_gw = nla ? nla_get_be32(nla) : 0;
    #ifdef CONFIG_IP_ROUTE_CLASSID
    			nla = nla_find(attrs, attrlen, RTA_FLOW);
    			nexthop_nh->nh_tclassid = nla ? nla_get_u32(nla) : 0;
    			if (nexthop_nh->nh_tclassid)
    				fi->fib_net->ipv4.fib_num_tclassid_users++;
    #endif
    		}
    
    		rtnh = rtnh_next(rtnh, &remaining);
    	} endfor_nexthops(fi);
    
    	return 0;
    }
    
    #endif
    
    int fib_nh_match(struct fib_config *cfg, struct fib_info *fi)
    {
    #ifdef CONFIG_IP_ROUTE_MULTIPATH
    	struct rtnexthop *rtnh;
    	int remaining;
    #endif
    
    	if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
    		return 1;
    
    	if (cfg->fc_oif || cfg->fc_gw) {
    		if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->nh_oif) &&
    		    (!cfg->fc_gw  || cfg->fc_gw == fi->fib_nh->nh_gw))
    			return 0;
    		return 1;
    	}
    
    #ifdef CONFIG_IP_ROUTE_MULTIPATH
    	if (cfg->fc_mp == NULL)
    		return 0;
    
    	rtnh = cfg->fc_mp;
    	remaining = cfg->fc_mp_len;
    
    	for_nexthops(fi) {
    		int attrlen;
    
    		if (!rtnh_ok(rtnh, remaining))
    			return -EINVAL;
    
    		if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->nh_oif)
    			return 1;
    
    		attrlen = rtnh_attrlen(rtnh);
    		if (attrlen < 0) {
    			struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
    
    			nla = nla_find(attrs, attrlen, RTA_GATEWAY);
    			if (nla && nla_get_be32(nla) != nh->nh_gw)
    				return 1;
    #ifdef CONFIG_IP_ROUTE_CLASSID
    			nla = nla_find(attrs, attrlen, RTA_FLOW);
    			if (nla && nla_get_u32(nla) != nh->nh_tclassid)
    				return 1;
    #endif
    		}
    
    		rtnh = rtnh_next(rtnh, &remaining);
    	} endfor_nexthops(fi);
    #endif
    	return 0;
    }
    
    
    /*
     * Picture
     * -------
     *
     * Semantics of nexthop is very messy by historical reasons.
     * We have to take into account, that:
     * a) gateway can be actually local interface address,
     *    so that gatewayed route is direct.
     * b) gateway must be on-link address, possibly
     *    described not by an ifaddr, but also by a direct route.
     * c) If both gateway and interface are specified, they should not
     *    contradict.
     * d) If we use tunnel routes, gateway could be not on-link.
     *
     * Attempt to reconcile all of these (alas, self-contradictory) conditions
     * results in pretty ugly and hairy code with obscure logic.
     *
     * I chose to generalized it instead, so that the size
     * of code does not increase practically, but it becomes
     * much more general.
     * Every prefix is assigned a "scope" value: "host" is local address,
     * "link" is direct route,
     * [ ... "site" ... "interior" ... ]
     * and "universe" is true gateway route with global meaning.
     *
     * Every prefix refers to a set of "nexthop"s (gw, oif),
     * where gw must have narrower scope. This recursion stops
     * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
     * which means that gw is forced to be on link.
     *
     * Code is still hairy, but now it is apparently logically
     * consistent and very flexible. F.e. as by-product it allows
     * to co-exists in peace independent exterior and interior
     * routing processes.
     *
     * Normally it looks as following.
     *
     * {universe prefix}  -> (gw, oif) [scope link]
     *		  |
     *		  |-> {link prefix} -> (gw, oif) [scope local]
     *					|
     *					|-> {local prefix} (terminal node)
     */
    static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
    			struct fib_nh *nh)
    {
    	int err;
    	struct net *net;
    	struct net_device *dev;
    
    	net = cfg->fc_nlinfo.nl_net;
    	if (nh->nh_gw) {
    		struct fib_result res;
    
    		if (nh->nh_flags & RTNH_F_ONLINK) {
    
    			if (cfg->fc_scope >= RT_SCOPE_LINK)
    				return -EINVAL;
    			if (inet_addr_type(net, nh->nh_gw) != RTN_UNICAST)
    				return -EINVAL;
    			dev = __dev_get_by_index(net, nh->nh_oif);
    			if (!dev)
    				return -ENODEV;
    			if (!(dev->flags & IFF_UP))
    				return -ENETDOWN;
    			nh->nh_dev = dev;
    			dev_hold(dev);
    			nh->nh_scope = RT_SCOPE_LINK;
    			return 0;
    		}
    		rcu_read_lock();
    		{
    			struct flowi4 fl4 = {
    				.daddr = nh->nh_gw,
    				.flowi4_scope = cfg->fc_scope + 1,
    				.flowi4_oif = nh->nh_oif,
    			};
    
    			/* It is not necessary, but requires a bit of thinking */
    			if (fl4.flowi4_scope < RT_SCOPE_LINK)
    				fl4.flowi4_scope = RT_SCOPE_LINK;
    			err = fib_lookup(net, &fl4, &res);
    			if (err) {
    				rcu_read_unlock();
    				return err;
    			}
    		}
    		err = -EINVAL;
    		if (res.type != RTN_UNICAST && res.type != RTN_LOCAL)
    			goto out;
    		nh->nh_scope = res.scope;
    		nh->nh_oif = FIB_RES_OIF(res);
    		nh->nh_dev = dev = FIB_RES_DEV(res);
    		if (!dev)
    			goto out;
    		dev_hold(dev);
    		err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
    	} else {
    		struct in_device *in_dev;
    
    		if (nh->nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK))
    			return -EINVAL;
    
    		rcu_read_lock();
    		err = -ENODEV;
    		in_dev = inetdev_by_index(net, nh->nh_oif);
    		if (in_dev == NULL)
    			goto out;
    		err = -ENETDOWN;
    		if (!(in_dev->dev->flags & IFF_UP))
    			goto out;
    		nh->nh_dev = in_dev->dev;
    		dev_hold(nh->nh_dev);
    		nh->nh_scope = RT_SCOPE_HOST;
    		err = 0;
    	}
    out:
    	rcu_read_unlock();
    	return err;
    }
    
    static inline unsigned int fib_laddr_hashfn(__be32 val)
    {
    	unsigned int mask = (fib_info_hash_size - 1);
    
    	return ((__force u32)val ^
    		((__force u32)val >> 7) ^
    		((__force u32)val >> 14)) & mask;
    }
    
    static struct hlist_head *fib_info_hash_alloc(int bytes)
    {
    	if (bytes <= PAGE_SIZE)
    		return kzalloc(bytes, GFP_KERNEL);
    	else
    		return (struct hlist_head *)
    			__get_free_pages(GFP_KERNEL | __GFP_ZERO,
    					 get_order(bytes));
    }
    
    static void fib_info_hash_free(struct hlist_head *hash, int bytes)
    {
    	if (!hash)
    		return;
    
    	if (bytes <= PAGE_SIZE)
    		kfree(hash);
    	else
    		free_pages((unsigned long) hash, get_order(bytes));
    }
    
    static void fib_info_hash_move(struct hlist_head *new_info_hash,
    			       struct hlist_head *new_laddrhash,
    			       unsigned int new_size)
    {
    	struct hlist_head *old_info_hash, *old_laddrhash;
    	unsigned int old_size = fib_info_hash_size;
    	unsigned int i, bytes;
    
    	spin_lock_bh(&fib_info_lock);
    	old_info_hash = fib_info_hash;
    	old_laddrhash = fib_info_laddrhash;
    	fib_info_hash_size = new_size;
    
    	for (i = 0; i < old_size; i++) {
    		struct hlist_head *head = &fib_info_hash[i];
    		struct hlist_node *node, *n;
    		struct fib_info *fi;
    
    		hlist_for_each_entry_safe(fi, node, n, head, fib_hash) {
    			struct hlist_head *dest;
    			unsigned int new_hash;
    
    			hlist_del(&fi->fib_hash);
    
    			new_hash = fib_info_hashfn(fi);
    			dest = &new_info_hash[new_hash];
    			hlist_add_head(&fi->fib_hash, dest);
    		}
    	}
    	fib_info_hash = new_info_hash;
    
    	for (i = 0; i < old_size; i++) {
    		struct hlist_head *lhead = &fib_info_laddrhash[i];
    		struct hlist_node *node, *n;
    		struct fib_info *fi;
    
    		hlist_for_each_entry_safe(fi, node, n, lhead, fib_lhash) {
    			struct hlist_head *ldest;
    			unsigned int new_hash;
    
    			hlist_del(&fi->fib_lhash);
    
    			new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
    			ldest = &new_laddrhash[new_hash];
    			hlist_add_head(&fi->fib_lhash, ldest);
    		}
    	}
    	fib_info_laddrhash = new_laddrhash;
    
    	spin_unlock_bh(&fib_info_lock);
    
    	bytes = old_size * sizeof(struct hlist_head *);
    	fib_info_hash_free(old_info_hash, bytes);
    	fib_info_hash_free(old_laddrhash, bytes);
    }
    
    __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh)
    {
    	nh->nh_saddr = inet_select_addr(nh->nh_dev,
    					nh->nh_gw,
    					nh->nh_parent->fib_scope);
    	nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
    
    	return nh->nh_saddr;
    }
    
    struct fib_info *fib_create_info(struct fib_config *cfg)
    {
    	int err;
    	struct fib_info *fi = NULL;
    	struct fib_info *ofi;
    	int nhs = 1;
    	struct net *net = cfg->fc_nlinfo.nl_net;
    
    	if (cfg->fc_type > RTN_MAX)
    		goto err_inval;
    
    	/* Fast check to catch the most weird cases */
    	if (fib_props[cfg->fc_type].scope > cfg->fc_scope)
    		goto err_inval;
    
    #ifdef CONFIG_IP_ROUTE_MULTIPATH
    	if (cfg->fc_mp) {
    		nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len);
    		if (nhs == 0)
    			goto err_inval;
    	}
    #endif
    
    	err = -ENOBUFS;
    	if (fib_info_cnt >= fib_info_hash_size) {
    		unsigned int new_size = fib_info_hash_size << 1;
    		struct hlist_head *new_info_hash;
    		struct hlist_head *new_laddrhash;
    		unsigned int bytes;
    
    		if (!new_size)
    			new_size = 1;
    		bytes = new_size * sizeof(struct hlist_head *);
    		new_info_hash = fib_info_hash_alloc(bytes);
    		new_laddrhash = fib_info_hash_alloc(bytes);
    		if (!new_info_hash || !new_laddrhash) {
    			fib_info_hash_free(new_info_hash, bytes);
    			fib_info_hash_free(new_laddrhash, bytes);
    		} else
    			fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
    
    		if (!fib_info_hash_size)
    			goto failure;
    	}
    
    	fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct fib_nh), GFP_KERNEL);
    	if (fi == NULL)
    		goto failure;
    	if (cfg->fc_mx) {
    		fi->fib_metrics = kzalloc(sizeof(u32) * RTAX_MAX, GFP_KERNEL);
    		if (!fi->fib_metrics)
    			goto failure;
    	} else
    		fi->fib_metrics = (u32 *) dst_default_metrics;
    	fib_info_cnt++;
    
    	fi->fib_net = hold_net(net);
    	fi->fib_protocol = cfg->fc_protocol;
    	fi->fib_scope = cfg->fc_scope;
    	fi->fib_flags = cfg->fc_flags;
    	fi->fib_priority = cfg->fc_priority;
    	fi->fib_prefsrc = cfg->fc_prefsrc;
    	fi->fib_type = cfg->fc_type;
    
    	fi->fib_nhs = nhs;
    	change_nexthops(fi) {
    		nexthop_nh->nh_parent = fi;
    		nexthop_nh->nh_pcpu_rth_output = alloc_percpu(struct rtable __rcu *);
    		if (!nexthop_nh->nh_pcpu_rth_output)
    			goto failure;
    	} endfor_nexthops(fi)
    
    	if (cfg->fc_mx) {
    		struct nlattr *nla;
    		int remaining;
    
    		nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
    			int type = nla_type(nla);
    
    			if (type) {
    				u32 val;
    
    				if (type > RTAX_MAX)
    					goto err_inval;
    				val = nla_get_u32(nla);
    				if (type == RTAX_ADVMSS && val > 65535 - 40)
    					val = 65535 - 40;
    				if (type == RTAX_MTU && val > 65535 - 15)
    					val = 65535 - 15;
    				fi->fib_metrics[type - 1] = val;
    			}
    		}
    	}
    
    	if (cfg->fc_mp) {
    #ifdef CONFIG_IP_ROUTE_MULTIPATH
    		err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg);
    		if (err != 0)
    			goto failure;
    		if (cfg->fc_oif && fi->fib_nh->nh_oif != cfg->fc_oif)
    			goto err_inval;
    		if (cfg->fc_gw && fi->fib_nh->nh_gw != cfg->fc_gw)
    			goto err_inval;
    #ifdef CONFIG_IP_ROUTE_CLASSID
    		if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow)
    			goto err_inval;
    #endif
    #else
    		goto err_inval;
    #endif
    	} else {
    		struct fib_nh *nh = fi->fib_nh;
    
    		nh->nh_oif = cfg->fc_oif;
    		nh->nh_gw = cfg->fc_gw;
    		nh->nh_flags = cfg->fc_flags;
    #ifdef CONFIG_IP_ROUTE_CLASSID
    		nh->nh_tclassid = cfg->fc_flow;
    		if (nh->nh_tclassid)
    			fi->fib_net->ipv4.fib_num_tclassid_users++;
    #endif
    #ifdef CONFIG_IP_ROUTE_MULTIPATH
    		nh->nh_weight = 1;
    #endif
    	}
    
    	if (fib_props[cfg->fc_type].error) {
    		if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp)
    			goto err_inval;
    		goto link_it;
    	} else {
    		switch (cfg->fc_type) {
    		case RTN_UNICAST:
    		case RTN_LOCAL:
    		case RTN_BROADCAST:
    		case RTN_ANYCAST:
    		case RTN_MULTICAST:
    			break;
    		default:
    			goto err_inval;
    		}
    	}
    
    	if (cfg->fc_scope > RT_SCOPE_HOST)
    		goto err_inval;
    
    	if (cfg->fc_scope == RT_SCOPE_HOST) {
    		struct 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(net, fi->fib_nh->nh_oif);
    		err = -ENODEV;
    		if (nh->nh_dev == NULL)
    			goto failure;
    	} else {
    		change_nexthops(fi) {
    			err = fib_check_nh(cfg, fi, nexthop_nh);
    			if (err != 0)
    				goto failure;
    		} endfor_nexthops(fi)
    	}
    
    	if (fi->fib_prefsrc) {
    		if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
    		    fi->fib_prefsrc != cfg->fc_dst)
    			if (inet_addr_type(net, fi->fib_prefsrc) != RTN_LOCAL)
    				goto err_inval;
    	}
    
    	change_nexthops(fi) {
    		fib_info_update_nh_saddr(net, nexthop_nh);
    	} endfor_nexthops(fi)
    
    link_it:
    	ofi = fib_find_info(fi);
    	if (ofi) {
    		fi->fib_dead = 1;
    		free_fib_info(fi);
    		ofi->fib_treeref++;
    		return ofi;
    	}
    
    	fi->fib_treeref++;
    	atomic_inc(&fi->fib_clntref);
    	spin_lock_bh(&fib_info_lock);
    	hlist_add_head(&fi->fib_hash,
    		       &fib_info_hash[fib_info_hashfn(fi)]);
    	if (fi->fib_prefsrc) {
    		struct hlist_head *head;
    
    		head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
    		hlist_add_head(&fi->fib_lhash, head);
    	}
    	change_nexthops(fi) {
    		struct hlist_head *head;
    		unsigned int hash;
    
    		if (!nexthop_nh->nh_dev)
    			continue;
    		hash = fib_devindex_hashfn(nexthop_nh->nh_dev->ifindex);
    		head = &fib_info_devhash[hash];
    		hlist_add_head(&nexthop_nh->nh_hash, head);
    	} endfor_nexthops(fi)
    	spin_unlock_bh(&fib_info_lock);
    	return fi;
    
    err_inval:
    	err = -EINVAL;
    
    failure:
    	if (fi) {
    		fi->fib_dead = 1;
    		free_fib_info(fi);
    	}
    
    	return ERR_PTR(err);
    }
    
    int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
    		  u32 tb_id, u8 type, __be32 dst, int dst_len, u8 tos,
    		  struct fib_info *fi, unsigned int flags)
    {
    	struct nlmsghdr *nlh;
    	struct rtmsg *rtm;
    
    	nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
    	if (nlh == NULL)
    		return -EMSGSIZE;
    
    	rtm = nlmsg_data(nlh);
    	rtm->rtm_family = AF_INET;
    	rtm->rtm_dst_len = dst_len;
    	rtm->rtm_src_len = 0;
    	rtm->rtm_tos = tos;
    	if (tb_id < 256)
    		rtm->rtm_table = tb_id;
    	else
    		rtm->rtm_table = RT_TABLE_COMPAT;
    	if (nla_put_u32(skb, RTA_TABLE, tb_id))
    		goto nla_put_failure;
    	rtm->rtm_type = type;
    	rtm->rtm_flags = fi->fib_flags;
    	rtm->rtm_scope = fi->fib_scope;
    	rtm->rtm_protocol = fi->fib_protocol;
    
    	if (rtm->rtm_dst_len &&
    	    nla_put_be32(skb, RTA_DST, dst))
    		goto nla_put_failure;
    	if (fi->fib_priority &&
    	    nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
    		goto nla_put_failure;
    	if (rtnetlink_put_metrics(skb, fi->fib_metrics) < 0)
    		goto nla_put_failure;
    
    	if (fi->fib_prefsrc &&
    	    nla_put_be32(skb, RTA_PREFSRC, fi->fib_prefsrc))
    		goto nla_put_failure;
    	if (fi->fib_nhs == 1) {
    		if (fi->fib_nh->nh_gw &&
    		    nla_put_be32(skb, RTA_GATEWAY, fi->fib_nh->nh_gw))
    			goto nla_put_failure;
    		if (fi->fib_nh->nh_oif &&
    		    nla_put_u32(skb, RTA_OIF, fi->fib_nh->nh_oif))
    			goto nla_put_failure;
    #ifdef CONFIG_IP_ROUTE_CLASSID
    		if (fi->fib_nh[0].nh_tclassid &&
    		    nla_put_u32(skb, RTA_FLOW, fi->fib_nh[0].nh_tclassid))
    			goto nla_put_failure;
    #endif
    	}
    #ifdef CONFIG_IP_ROUTE_MULTIPATH
    	if (fi->fib_nhs > 1) {
    		struct rtnexthop *rtnh;
    		struct nlattr *mp;
    
    		mp = nla_nest_start(skb, RTA_MULTIPATH);
    		if (mp == NULL)
    			goto nla_put_failure;
    
    		for_nexthops(fi) {
    			rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
    			if (rtnh == NULL)
    				goto nla_put_failure;
    
    			rtnh->rtnh_flags = nh->nh_flags & 0xFF;
    			rtnh->rtnh_hops = nh->nh_weight - 1;
    			rtnh->rtnh_ifindex = nh->nh_oif;
    
    			if (nh->nh_gw &&
    			    nla_put_be32(skb, RTA_GATEWAY, nh->nh_gw))
    				goto nla_put_failure;
    #ifdef CONFIG_IP_ROUTE_CLASSID
    			if (nh->nh_tclassid &&
    			    nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
    				goto nla_put_failure;
    #endif
    			/* length of rtnetlink header + attributes */
    			rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *) rtnh;
    		} endfor_nexthops(fi);
    
    		nla_nest_end(skb, mp);
    	}
    #endif
    	return nlmsg_end(skb, nlh);
    
    nla_put_failure:
    	nlmsg_cancel(skb, nlh);
    	return -EMSGSIZE;
    }
    
    /*
     * Update FIB if:
     * - local address disappeared -> we must delete all the entries
     *   referring to it.
     * - device went down -> we must shutdown all nexthops going via it.
     */
    int fib_sync_down_addr(struct net *net, __be32 local)
    {
    	int ret = 0;
    	unsigned int hash = fib_laddr_hashfn(local);
    	struct hlist_head *head = &fib_info_laddrhash[hash];
    	struct hlist_node *node;
    	struct fib_info *fi;
    
    	if (fib_info_laddrhash == NULL || local == 0)
    		return 0;
    
    	hlist_for_each_entry(fi, node, head, fib_lhash) {
    		if (!net_eq(fi->fib_net, net))
    			continue;
    		if (fi->fib_prefsrc == local) {
    			fi->fib_flags |= RTNH_F_DEAD;
    			ret++;
    		}
    	}
    	return ret;
    }
    
    int fib_sync_down_dev(struct net_device *dev, int force)
    {
    	int ret = 0;
    	int scope = RT_SCOPE_NOWHERE;
    	struct fib_info *prev_fi = NULL;
    	unsigned int hash = fib_devindex_hashfn(dev->ifindex);
    	struct hlist_head *head = &fib_info_devhash[hash];
    	struct hlist_node *node;
    	struct fib_nh *nh;
    
    	if (force)
    		scope = -1;
    
    	hlist_for_each_entry(nh, node, head, nh_hash) {
    		struct fib_info *fi = nh->nh_parent;
    		int dead;
    
    		BUG_ON(!fi->fib_nhs);
    		if (nh->nh_dev != dev || fi == prev_fi)
    			continue;
    		prev_fi = fi;
    		dead = 0;
    		change_nexthops(fi) {
    			if (nexthop_nh->nh_flags & RTNH_F_DEAD)
    				dead++;
    			else if (nexthop_nh->nh_dev == dev &&
    				 nexthop_nh->nh_scope != scope) {
    				nexthop_nh->nh_flags |= RTNH_F_DEAD;
    #ifdef CONFIG_IP_ROUTE_MULTIPATH
    				spin_lock_bh(&fib_multipath_lock);
    				fi->fib_power -= nexthop_nh->nh_power;
    				nexthop_nh->nh_power = 0;
    				spin_unlock_bh(&fib_multipath_lock);
    #endif
    				dead++;
    			}
    #ifdef CONFIG_IP_ROUTE_MULTIPATH
    			if (force > 1 && nexthop_nh->nh_dev == dev) {
    				dead = fi->fib_nhs;
    				break;
    			}
    #endif
    		} endfor_nexthops(fi)
    		if (dead == fi->fib_nhs) {
    			fi->fib_flags |= RTNH_F_DEAD;
    			ret++;
    		}
    	}
    
    	return ret;
    }
    
    /* Must be invoked inside of an RCU protected region.  */
    void fib_select_default(struct fib_result *res)
    {
    	struct fib_info *fi = NULL, *last_resort = NULL;
    	struct list_head *fa_head = res->fa_head;
    	struct fib_table *tb = res->table;
    	int order = -1, last_idx = -1;
    	struct fib_alias *fa;
    
    	list_for_each_entry_rcu(fa, fa_head, fa_list) {
    		struct fib_info *next_fi = fa->fa_info;
    
    		if (next_fi->fib_scope != res->scope ||
    		    fa->fa_type != RTN_UNICAST)
    			continue;
    
    		if (next_fi->fib_priority > res->fi->fib_priority)
    			break;
    		if (!next_fi->fib_nh[0].nh_gw ||
    		    next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK)
    			continue;
    
    		fib_alias_accessed(fa);
    
    		if (fi == NULL) {
    			if (next_fi != res->fi)
    				break;
    		} else if (!fib_detect_death(fi, order, &last_resort,
    					     &last_idx, tb->tb_default)) {
    			fib_result_assign(res, fi);
    			tb->tb_default = order;
    			goto out;
    		}
    		fi = next_fi;
    		order++;
    	}
    
    	if (order <= 0 || fi == NULL) {
    		tb->tb_default = -1;
    		goto out;
    	}
    
    	if (!fib_detect_death(fi, order, &last_resort, &last_idx,
    				tb->tb_default)) {
    		fib_result_assign(res, fi);
    		tb->tb_default = order;
    		goto out;
    	}
    
    	if (last_idx >= 0)
    		fib_result_assign(res, last_resort);
    	tb->tb_default = last_idx;
    out:
    	return;
    }
    
    #ifdef CONFIG_IP_ROUTE_MULTIPATH
    
    /*
     * Dead device goes up. We wake up dead nexthops.
     * It takes sense only on multipath routes.
     */
    int fib_sync_up(struct net_device *dev)
    {
    	struct fib_info *prev_fi;
    	unsigned int hash;
    	struct hlist_head *head;
    	struct hlist_node *node;
    	struct fib_nh *nh;
    	int ret;
    
    	if (!(dev->flags & IFF_UP))
    		return 0;
    
    	prev_fi = NULL;
    	hash = fib_devindex_hashfn(dev->ifindex);
    	head = &fib_info_devhash[hash];
    	ret = 0;
    
    	hlist_for_each_entry(nh, node, head, nh_hash) {
    		struct fib_info *fi = nh->nh_parent;
    		int alive;
    
    		BUG_ON(!fi->fib_nhs);
    		if (nh->nh_dev != dev || fi == prev_fi)
    			continue;
    
    		prev_fi = fi;
    		alive = 0;
    		change_nexthops(fi) {
    			if (!(nexthop_nh->nh_flags & RTNH_F_DEAD)) {
    				alive++;
    				continue;
    			}
    			if (nexthop_nh->nh_dev == NULL ||
    			    !(nexthop_nh->nh_dev->flags & IFF_UP))
    				continue;
    			if (nexthop_nh->nh_dev != dev ||
    			    !__in_dev_get_rtnl(dev))
    				continue;
    			alive++;
    			spin_lock_bh(&fib_multipath_lock);
    			nexthop_nh->nh_power = 0;
    			nexthop_nh->nh_flags &= ~RTNH_F_DEAD;
    			spin_unlock_bh(&fib_multipath_lock);
    		} endfor_nexthops(fi)
    
    		if (alive > 0) {
    			fi->fib_flags &= ~RTNH_F_DEAD;
    			ret++;
    		}
    	}
    
    	return ret;
    }
    
    /*
     * The algorithm is suboptimal, but it provides really
     * fair weighted route distribution.
     */
    void fib_select_multipath(struct fib_result *res)
    {
    	struct fib_info *fi = res->fi;
    	int w;
    
    	spin_lock_bh(&fib_multipath_lock);
    	if (fi->fib_power <= 0) {
    		int power = 0;
    		change_nexthops(fi) {
    			if (!(nexthop_nh->nh_flags & RTNH_F_DEAD)) {
    				power += nexthop_nh->nh_weight;
    				nexthop_nh->nh_power = nexthop_nh->nh_weight;
    			}
    		} endfor_nexthops(fi);
    		fi->fib_power = power;
    		if (power <= 0) {
    			spin_unlock_bh(&fib_multipath_lock);
    			/* Race condition: route has just become dead. */
    			res->nh_sel = 0;
    			return;
    		}
    	}
    
    
    	/* w should be random number [0..fi->fib_power-1],
    	 * it is pretty bad approximation.
    	 */
    
    	w = jiffies % fi->fib_power;
    
    	change_nexthops(fi) {
    		if (!(nexthop_nh->nh_flags & RTNH_F_DEAD) &&
    		    nexthop_nh->nh_power) {
    			w -= nexthop_nh->nh_power;
    			if (w <= 0) {
    				nexthop_nh->nh_power--;
    				fi->fib_power--;
    				res->nh_sel = nhsel;
    				spin_unlock_bh(&fib_multipath_lock);
    				return;
    			}
    		}
    	} endfor_nexthops(fi);
    
    	/* Race condition: route has just become dead. */
    	res->nh_sel = 0;
    	spin_unlock_bh(&fib_multipath_lock);
    }
    #endif