ClabureDB: Classified Bug-Reports Database

   /*
    *        Linux INET6 implementation
    *        Forwarding Information Database
    *
    *        Authors:
    *        Pedro Roque                <roque@di.fc.ul.pt>
    *
    *        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.
   */
  
  /*
   *         Changes:
   *         Yuji SEKIYA @USAGI:        Support default route on router node;
   *                                 remove ip6_null_entry from the top of
   *                                 routing table.
   *         Ville Nuorvala:                Fixed routing subtrees.
   */
  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/net.h>
  #include <linux/route.h>
  #include <linux/netdevice.h>
  #include <linux/in6.h>
  #include <linux/init.h>
  #include <linux/list.h>
  
  #ifdef         CONFIG_PROC_FS
  #include <linux/proc_fs.h>
  #endif
  
  #include <net/ipv6.h>
  #include <net/ndisc.h>
  #include <net/addrconf.h>
  
  #include <net/ip6_fib.h>
  #include <net/ip6_route.h>
  
  #define RT6_DEBUG 2
  
  #if RT6_DEBUG >= 3
  #define RT6_TRACE(x...) printk(KERN_DEBUG x)
  #else
  #define RT6_TRACE(x...) do { ; } while (0)
  #endif
  
  static struct kmem_cache * fib6_node_kmem __read_mostly;
  
  enum fib_walk_state_t
  {
  #ifdef CONFIG_IPV6_SUBTREES
          FWS_S,
  #endif
          FWS_L,
          FWS_R,
          FWS_C,
          FWS_U
  };
  
  struct fib6_cleaner_t
  {
          struct fib6_walker_t w;
          struct net *net;
          int (*func)(struct rt6_info *, void *arg);
          void *arg;
  };
  
  static DEFINE_RWLOCK(fib6_walker_lock);
  
  #ifdef CONFIG_IPV6_SUBTREES
  #define FWS_INIT FWS_S
  #else
  #define FWS_INIT FWS_L
  #endif
  
  static void fib6_prune_clones(struct net *net, struct fib6_node *fn,
                                struct rt6_info *rt);
  static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn);
  static struct fib6_node *fib6_repair_tree(struct net *net, struct fib6_node *fn);
  static int fib6_walk(struct fib6_walker_t *w);
  static int fib6_walk_continue(struct fib6_walker_t *w);
  
  /*
   *        A routing update causes an increase of the serial number on the
   *        affected subtree. This allows for cached routes to be asynchronously
   *        tested when modifications are made to the destination cache as a
   *        result of redirects, path MTU changes, etc.
   */
  
  static __u32 rt_sernum;
  
  static void fib6_gc_timer_cb(unsigned long arg);
  
  static struct fib6_walker_t fib6_walker_list = {
          .prev        = &fib6_walker_list,
          .next        = &fib6_walker_list,
  };
 
 #define FOR_WALKERS(w) for ((w)=fib6_walker_list.next; (w) != &fib6_walker_list; (w)=(w)->next)
 
 static inline void fib6_walker_link(struct fib6_walker_t *w)
 {
         write_lock_bh(&fib6_walker_lock);
         w->next = fib6_walker_list.next;
         w->prev = &fib6_walker_list;
         w->next->prev = w;
         w->prev->next = w;
         write_unlock_bh(&fib6_walker_lock);
 }
 
 static inline void fib6_walker_unlink(struct fib6_walker_t *w)
 {
         write_lock_bh(&fib6_walker_lock);
         w->next->prev = w->prev;
         w->prev->next = w->next;
         w->prev = w->next = w;
         write_unlock_bh(&fib6_walker_lock);
 }
 static __inline__ u32 fib6_new_sernum(void)
 {
         u32 n = ++rt_sernum;
         if ((__s32)n <= 0)
                 rt_sernum = n = 1;
         return n;
 }
 
 /*
  *        Auxiliary address test functions for the radix tree.
  *
  *        These assume a 32bit processor (although it will work on
  *        64bit processors)
  */
 
 /*
  *        test bit
  */
 
 static __inline__ __be32 addr_bit_set(void *token, int fn_bit)
 {
         __be32 *addr = token;
 
         return htonl(1 << ((~fn_bit)&0x1F)) & addr[fn_bit>>5];
 }
 
 static __inline__ struct fib6_node * node_alloc(void)
 {
         struct fib6_node *fn;
 
         fn = kmem_cache_zalloc(fib6_node_kmem, GFP_ATOMIC);
 
         return fn;
 }
 
 static __inline__ void node_free(struct fib6_node * fn)
 {
         kmem_cache_free(fib6_node_kmem, fn);
 }
 
 static __inline__ void rt6_release(struct rt6_info *rt)
 {
         if (atomic_dec_and_test(&rt->rt6i_ref))
                 dst_free(&rt->u.dst);
 }
 
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 #define FIB_TABLE_HASHSZ 256
 #else
 #define FIB_TABLE_HASHSZ 1
 #endif
 
 static void fib6_link_table(struct net *net, struct fib6_table *tb)
 {
         unsigned int h;
 
         /*
          * Initialize table lock at a single place to give lockdep a key,
          * tables aren't visible prior to being linked to the list.
          */
         rwlock_init(&tb->tb6_lock);
 
         h = tb->tb6_id & (FIB_TABLE_HASHSZ - 1);
 
         /*
          * No protection necessary, this is the only list mutatation
          * operation, tables never disappear once they exist.
          */
         hlist_add_head_rcu(&tb->tb6_hlist, &net->ipv6.fib_table_hash[h]);
 }
 
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 
 static struct fib6_table *fib6_alloc_table(struct net *net, u32 id)
 {
         struct fib6_table *table;
 
         table = kzalloc(sizeof(*table), GFP_ATOMIC);
         if (table != NULL) {
                 table->tb6_id = id;
                 table->tb6_root.leaf = net->ipv6.ip6_null_entry;
                 table->tb6_root.fn_flags = RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
         }
 
         return table;
 }
 
 struct fib6_table *fib6_new_table(struct net *net, u32 id)
 {
         struct fib6_table *tb;
 
         if (id == 0)
                 id = RT6_TABLE_MAIN;
         tb = fib6_get_table(net, id);
         if (tb)
                 return tb;
 
         tb = fib6_alloc_table(net, id);
         if (tb != NULL)
                 fib6_link_table(net, tb);
 
         return tb;
 }
 
 struct fib6_table *fib6_get_table(struct net *net, u32 id)
 {
         struct fib6_table *tb;
         struct hlist_head *head;
         struct hlist_node *node;
         unsigned int h;
 
         if (id == 0)
                 id = RT6_TABLE_MAIN;
         h = id & (FIB_TABLE_HASHSZ - 1);
         rcu_read_lock();
         head = &net->ipv6.fib_table_hash[h];
         hlist_for_each_entry_rcu(tb, node, head, tb6_hlist) {
                 if (tb->tb6_id == id) {
                         rcu_read_unlock();
                         return tb;
                 }
         }
         rcu_read_unlock();
 
         return NULL;
 }
 
 static void fib6_tables_init(struct net *net)
 {
         fib6_link_table(net, net->ipv6.fib6_main_tbl);
         fib6_link_table(net, net->ipv6.fib6_local_tbl);
 }
 #else
 
 struct fib6_table *fib6_new_table(struct net *net, u32 id)
 {
         return fib6_get_table(net, id);
 }
 
 struct fib6_table *fib6_get_table(struct net *net, u32 id)
 {
           return net->ipv6.fib6_main_tbl;
 }
 
 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi *fl,
                                    int flags, pol_lookup_t lookup)
 {
         return (struct dst_entry *) lookup(net, net->ipv6.fib6_main_tbl, fl, flags);
 }
 
 static void fib6_tables_init(struct net *net)
 {
         fib6_link_table(net, net->ipv6.fib6_main_tbl);
 }
 
 #endif
 
 static int fib6_dump_node(struct fib6_walker_t *w)
 {
         int res;
         struct rt6_info *rt;
 
         for (rt = w->leaf; rt; rt = rt->u.dst.rt6_next) {
                 res = rt6_dump_route(rt, w->args);
                 if (res < 0) {
                         /* Frame is full, suspend walking */
                         w->leaf = rt;
                         return 1;
                 }
                 WARN_ON(res == 0);
         }
         w->leaf = NULL;
         return 0;
 }
 
 static void fib6_dump_end(struct netlink_callback *cb)
 {
         struct fib6_walker_t *w = (void*)cb->args[2];
 
         if (w) {
                 cb->args[2] = 0;
                 kfree(w);
         }
         cb->done = (void*)cb->args[3];
         cb->args[1] = 3;
 }
 
 static int fib6_dump_done(struct netlink_callback *cb)
 {
         fib6_dump_end(cb);
         return cb->done ? cb->done(cb) : 0;
 }
 
 static int fib6_dump_table(struct fib6_table *table, struct sk_buff *skb,
                            struct netlink_callback *cb)
 {
         struct fib6_walker_t *w;
         int res;
 
         w = (void *)cb->args[2];
         w->root = &table->tb6_root;
 
         if (cb->args[4] == 0) {
                 read_lock_bh(&table->tb6_lock);
                 res = fib6_walk(w);
                 read_unlock_bh(&table->tb6_lock);
                 if (res > 0)
                         cb->args[4] = 1;
         } else {
                 read_lock_bh(&table->tb6_lock);
                 res = fib6_walk_continue(w);
                 read_unlock_bh(&table->tb6_lock);
                 if (res != 0) {
                         if (res < 0)
                                 fib6_walker_unlink(w);
                         goto end;
                 }
                 fib6_walker_unlink(w);
                 cb->args[4] = 0;
         }
 end:
         return res;
 }
 
 static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
 {
         struct net *net = sock_net(skb->sk);
         unsigned int h, s_h;
         unsigned int e = 0, s_e;
         struct rt6_rtnl_dump_arg arg;
         struct fib6_walker_t *w;
         struct fib6_table *tb;
         struct hlist_node *node;
         struct hlist_head *head;
         int res = 0;
 
         s_h = cb->args[0];
         s_e = cb->args[1];
 
         w = (void *)cb->args[2];
         if (w == NULL) {
                 /* New dump:
                  *
                  * 1. hook callback destructor.
                  */
                 cb->args[3] = (long)cb->done;
                 cb->done = fib6_dump_done;
 
                 /*
                  * 2. allocate and initialize walker.
                  */
                 w = kzalloc(sizeof(*w), GFP_ATOMIC);
                 if (w == NULL)
                         return -ENOMEM;
                 w->func = fib6_dump_node;
                 cb->args[2] = (long)w;
         }
 
         arg.skb = skb;
         arg.cb = cb;
         arg.net = net;
         w->args = &arg;
 
         for (h = s_h; h < FIB_TABLE_HASHSZ; h++, s_e = 0) {
                 e = 0;
                 head = &net->ipv6.fib_table_hash[h];
                 hlist_for_each_entry(tb, node, head, tb6_hlist) {
                         if (e < s_e)
                                 goto next;
                         res = fib6_dump_table(tb, skb, cb);
                         if (res != 0)
                                 goto out;
 next:
                         e++;
                 }
         }
 out:
         cb->args[1] = e;
         cb->args[0] = h;
 
         res = res < 0 ? res : skb->len;
         if (res <= 0)
                 fib6_dump_end(cb);
         return res;
 }
 
 /*
  *        Routing Table
  *
  *        return the appropriate node for a routing tree "add" operation
  *        by either creating and inserting or by returning an existing
  *        node.
  */
 
 static struct fib6_node * fib6_add_1(struct fib6_node *root, void *addr,
                                      int addrlen, int plen,
                                      int offset)
 {
         struct fib6_node *fn, *in, *ln;
         struct fib6_node *pn = NULL;
         struct rt6key *key;
         int        bit;
         __be32        dir = 0;
         __u32        sernum = fib6_new_sernum();
 
         RT6_TRACE("fib6_add_1\n");
 
         /* insert node in tree */
 
         fn = root;
 
         do {
                 key = (struct rt6key *)((u8 *)fn->leaf + offset);
 
                 /*
                  *        Prefix match
                  */
                 if (plen < fn->fn_bit ||
                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit))
                         goto insert_above;
 
                 /*
                  *        Exact match ?
                  */
 
                 if (plen == fn->fn_bit) {
                         /* clean up an intermediate node */
                         if ((fn->fn_flags & RTN_RTINFO) == 0) {
                                 rt6_release(fn->leaf);
                                 fn->leaf = NULL;
                         }
 
                         fn->fn_sernum = sernum;
 
                         return fn;
                 }
 
                 /*
                  *        We have more bits to go
                  */
 
                 /* Try to walk down on tree. */
                 fn->fn_sernum = sernum;
                 dir = addr_bit_set(addr, fn->fn_bit);
                 pn = fn;
                 fn = dir ? fn->right: fn->left;
         } while (fn);
 
         /*
          *        We walked to the bottom of tree.
          *        Create new leaf node without children.
          */
 
         ln = node_alloc();
 
         if (ln == NULL)
                 return NULL;
         ln->fn_bit = plen;
 
         ln->parent = pn;
         ln->fn_sernum = sernum;
 
         if (dir)
                 pn->right = ln;
         else
                 pn->left  = ln;
 
         return ln;
 
 
 insert_above:
         /*
          * split since we don't have a common prefix anymore or
          * we have a less significant route.
          * we've to insert an intermediate node on the list
          * this new node will point to the one we need to create
          * and the current
          */
 
         pn = fn->parent;
 
         /* find 1st bit in difference between the 2 addrs.
 
            See comment in __ipv6_addr_diff: bit may be an invalid value,
            but if it is >= plen, the value is ignored in any case.
          */
 
         bit = __ipv6_addr_diff(addr, &key->addr, addrlen);
 
         /*
          *                (intermediate)[in]
          *                  /           \
          *        (new leaf node)[ln] (old node)[fn]
          */
         if (plen > bit) {
                 in = node_alloc();
                 ln = node_alloc();
 
                 if (in == NULL || ln == NULL) {
                         if (in)
                                 node_free(in);
                         if (ln)
                                 node_free(ln);
                         return NULL;
                 }
 
                 /*
                  * new intermediate node.
                  * RTN_RTINFO will
                  * be off since that an address that chooses one of
                  * the branches would not match less specific routes
                  * in the other branch
                  */
 
                 in->fn_bit = bit;
 
                 in->parent = pn;
                 in->leaf = fn->leaf;
                 atomic_inc(&in->leaf->rt6i_ref);
 
                 in->fn_sernum = sernum;
 
                 /* update parent pointer */
                 if (dir)
                         pn->right = in;
                 else
                         pn->left  = in;
 
                 ln->fn_bit = plen;
 
                 ln->parent = in;
                 fn->parent = in;
 
                 ln->fn_sernum = sernum;
 
                 if (addr_bit_set(addr, bit)) {
                         in->right = ln;
                         in->left  = fn;
                 } else {
                         in->left  = ln;
                         in->right = fn;
                 }
         } else { /* plen <= bit */
 
                 /*
                  *                (new leaf node)[ln]
                  *                  /           \
                  *             (old node)[fn] NULL
                  */
 
                 ln = node_alloc();
 
                 if (ln == NULL)
                         return NULL;
 
                 ln->fn_bit = plen;
 
                 ln->parent = pn;
 
                 ln->fn_sernum = sernum;
 
                 if (dir)
                         pn->right = ln;
                 else
                         pn->left  = ln;
 
                 if (addr_bit_set(&key->addr, plen))
                         ln->right = fn;
                 else
                         ln->left  = fn;
 
                 fn->parent = ln;
         }
         return ln;
 }
 
 /*
  *        Insert routing information in a node.
  */
 
 static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt,
                             struct nl_info *info)
 {
         struct rt6_info *iter = NULL;
         struct rt6_info **ins;
 
         ins = &fn->leaf;
 
         for (iter = fn->leaf; iter; iter=iter->u.dst.rt6_next) {
                 /*
                  *        Search for duplicates
                  */
 
                 if (iter->rt6i_metric == rt->rt6i_metric) {
                         /*
                          *        Same priority level
                          */
 
                         if (iter->rt6i_dev == rt->rt6i_dev &&
                             iter->rt6i_idev == rt->rt6i_idev &&
                             ipv6_addr_equal(&iter->rt6i_gateway,
                                             &rt->rt6i_gateway)) {
                                 if (!(iter->rt6i_flags&RTF_EXPIRES))
                                         return -EEXIST;
                                 iter->rt6i_expires = rt->rt6i_expires;
                                 if (!(rt->rt6i_flags&RTF_EXPIRES)) {
                                         iter->rt6i_flags &= ~RTF_EXPIRES;
                                         iter->rt6i_expires = 0;
                                 }
                                 return -EEXIST;
                         }
                 }
 
                 if (iter->rt6i_metric > rt->rt6i_metric)
                         break;
 
                 ins = &iter->u.dst.rt6_next;
         }
 
         /* Reset round-robin state, if necessary */
         if (ins == &fn->leaf)
                 fn->rr_ptr = NULL;
 
         /*
          *        insert node
          */
 
         rt->u.dst.rt6_next = iter;
         *ins = rt;
         rt->rt6i_node = fn;
         atomic_inc(&rt->rt6i_ref);
         inet6_rt_notify(RTM_NEWROUTE, rt, info);
         info->nl_net->ipv6.rt6_stats->fib_rt_entries++;
 
         if ((fn->fn_flags & RTN_RTINFO) == 0) {
                 info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
                 fn->fn_flags |= RTN_RTINFO;
         }
 
         return 0;
 }
 
 static __inline__ void fib6_start_gc(struct net *net, struct rt6_info *rt)
 {
         if (!timer_pending(&net->ipv6.ip6_fib_timer) &&
             (rt->rt6i_flags & (RTF_EXPIRES|RTF_CACHE)))
                 mod_timer(&net->ipv6.ip6_fib_timer,
                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
 }
 
 void fib6_force_start_gc(struct net *net)
 {
         if (!timer_pending(&net->ipv6.ip6_fib_timer))
                 mod_timer(&net->ipv6.ip6_fib_timer,
                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
 }
 
 /*
  *        Add routing information to the routing tree.
  *        <destination addr>/<source addr>
  *        with source addr info in sub-trees
  */
 
 int fib6_add(struct fib6_node *root, struct rt6_info *rt, struct nl_info *info)
 {
         struct fib6_node *fn, *pn = NULL;
         int err = -ENOMEM;
 
         fn = fib6_add_1(root, &rt->rt6i_dst.addr, sizeof(struct in6_addr),
                         rt->rt6i_dst.plen, offsetof(struct rt6_info, rt6i_dst));
 
         if (fn == NULL)
                 goto out;
 
         pn = fn;
 
 #ifdef CONFIG_IPV6_SUBTREES
         if (rt->rt6i_src.plen) {
                 struct fib6_node *sn;
 
                 if (fn->subtree == NULL) {
                         struct fib6_node *sfn;
 
                         /*
                          * Create subtree.
                          *
                          *                fn[main tree]
                          *                |
                          *                sfn[subtree root]
                          *                   \
                          *                    sn[new leaf node]
                          */
 
                         /* Create subtree root node */
                         sfn = node_alloc();
                         if (sfn == NULL)
                                 goto st_failure;
 
                         sfn->leaf = info->nl_net->ipv6.ip6_null_entry;
                         atomic_inc(&info->nl_net->ipv6.ip6_null_entry->rt6i_ref);
                         sfn->fn_flags = RTN_ROOT;
                         sfn->fn_sernum = fib6_new_sernum();
 
                         /* Now add the first leaf node to new subtree */
 
                         sn = fib6_add_1(sfn, &rt->rt6i_src.addr,
                                         sizeof(struct in6_addr), rt->rt6i_src.plen,
                                         offsetof(struct rt6_info, rt6i_src));
 
                         if (sn == NULL) {
                                 /* If it is failed, discard just allocated
                                    root, and then (in st_failure) stale node
                                    in main tree.
                                  */
                                 node_free(sfn);
                                 goto st_failure;
                         }
 
                         /* Now link new subtree to main tree */
                         sfn->parent = fn;
                         fn->subtree = sfn;
                 } else {
                         sn = fib6_add_1(fn->subtree, &rt->rt6i_src.addr,
                                         sizeof(struct in6_addr), rt->rt6i_src.plen,
                                         offsetof(struct rt6_info, rt6i_src));
 
                         if (sn == NULL)
                                 goto st_failure;
                 }
 
                 if (fn->leaf == NULL) {
                         fn->leaf = rt;
                         atomic_inc(&rt->rt6i_ref);
                 }
                 fn = sn;
         }
 #endif
 
         err = fib6_add_rt2node(fn, rt, info);
 
         if (err == 0) {
                 fib6_start_gc(info->nl_net, rt);
                 if (!(rt->rt6i_flags&RTF_CACHE))
                         fib6_prune_clones(info->nl_net, pn, rt);
         }
 
 out:
         if (err) {
 #ifdef CONFIG_IPV6_SUBTREES
                 /*
                  * If fib6_add_1 has cleared the old leaf pointer in the
                  * super-tree leaf node we have to find a new one for it.
                  */
                 if (pn != fn && pn->leaf == rt) {
                         pn->leaf = NULL;
                         atomic_dec(&rt->rt6i_ref);
                 }
                 if (pn != fn && !pn->leaf && !(pn->fn_flags & RTN_RTINFO)) {
                         pn->leaf = fib6_find_prefix(info->nl_net, pn);
 #if RT6_DEBUG >= 2
                         if (!pn->leaf) {
                                 WARN_ON(pn->leaf == NULL);
                                 pn->leaf = info->nl_net->ipv6.ip6_null_entry;
                         }
 #endif
                         atomic_inc(&pn->leaf->rt6i_ref);
                 }
 #endif
                 dst_free(&rt->u.dst);
         }
         return err;
 
 #ifdef CONFIG_IPV6_SUBTREES
         /* Subtree creation failed, probably main tree node
            is orphan. If it is, shoot it.
          */
 st_failure:
         if (fn && !(fn->fn_flags & (RTN_RTINFO|RTN_ROOT)))
                 fib6_repair_tree(info->nl_net, fn);
         dst_free(&rt->u.dst);
         return err;
 #endif
 }
 
 /*
  *        Routing tree lookup
  *
  */
 
 struct lookup_args {
         int                offset;                /* key offset on rt6_info        */
         struct in6_addr        *addr;                /* search key                        */
 };
 
 static struct fib6_node * fib6_lookup_1(struct fib6_node *root,
                                         struct lookup_args *args)
 {
         struct fib6_node *fn;
         __be32 dir;
 
         if (unlikely(args->offset == 0))
                 return NULL;
 
         /*
          *        Descend on a tree
          */
 
         fn = root;
 
         for (;;) {
                 struct fib6_node *next;
 
                 dir = addr_bit_set(args->addr, fn->fn_bit);
 
                 next = dir ? fn->right : fn->left;
 
                 if (next) {
                         fn = next;
                         continue;
                 }
 
                 break;
         }
 
         while(fn) {
                 if (FIB6_SUBTREE(fn) || fn->fn_flags & RTN_RTINFO) {
                         struct rt6key *key;
 
                         key = (struct rt6key *) ((u8 *) fn->leaf +
                                                  args->offset);
 
                         if (ipv6_prefix_equal(&key->addr, args->addr, key->plen)) {
 #ifdef CONFIG_IPV6_SUBTREES
                                 if (fn->subtree)
                                         fn = fib6_lookup_1(fn->subtree, args + 1);
 #endif
                                 if (!fn || fn->fn_flags & RTN_RTINFO)
                                         return fn;
                         }
                 }
 
                 if (fn->fn_flags & RTN_ROOT)
                         break;
 
                 fn = fn->parent;
         }
 
         return NULL;
 }
 
 struct fib6_node * fib6_lookup(struct fib6_node *root, struct in6_addr *daddr,
                                struct in6_addr *saddr)
 {
         struct fib6_node *fn;
         struct lookup_args args[] = {
                 {
                         .offset = offsetof(struct rt6_info, rt6i_dst),
                         .addr = daddr,
                 },
 #ifdef CONFIG_IPV6_SUBTREES
                 {
                         .offset = offsetof(struct rt6_info, rt6i_src),
                         .addr = saddr,
                 },
 #endif
                 {
                         .offset = 0,        /* sentinel */
                 }
         };
 
         fn = fib6_lookup_1(root, daddr ? args : args + 1);
 
         if (fn == NULL || fn->fn_flags & RTN_TL_ROOT)
                 fn = root;
 
         return fn;
 }
 
 /*
  *        Get node with specified destination prefix (and source prefix,
  *        if subtrees are used)
  */
 
 
 static struct fib6_node * fib6_locate_1(struct fib6_node *root,
                                         struct in6_addr *addr,
                                         int plen, int offset)
 {
         struct fib6_node *fn;
 
         for (fn = root; fn ; ) {
                 struct rt6key *key = (struct rt6key *)((u8 *)fn->leaf + offset);
 
                 /*
                  *        Prefix match
                  */
                 if (plen < fn->fn_bit ||
                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit))
                         return NULL;
 
                 if (plen == fn->fn_bit)
                         return fn;
 
                 /*
                  *        We have more bits to go
                  */
                 if (addr_bit_set(addr, fn->fn_bit))
                         fn = fn->right;
                 else
                         fn = fn->left;
         }
         return NULL;
 }
 
 struct fib6_node * fib6_locate(struct fib6_node *root,
                                struct in6_addr *daddr, int dst_len,
                                struct in6_addr *saddr, int src_len)
 {
         struct fib6_node *fn;
 
         fn = fib6_locate_1(root, daddr, dst_len,
                            offsetof(struct rt6_info, rt6i_dst));
 
 #ifdef CONFIG_IPV6_SUBTREES
         if (src_len) {
                 WARN_ON(saddr == NULL);
                 if (fn && fn->subtree)
                         fn = fib6_locate_1(fn->subtree, saddr, src_len,
                                            offsetof(struct rt6_info, rt6i_src));
         }
 #endif
 
         if (fn && fn->fn_flags&RTN_RTINFO)
                 return fn;
 
         return NULL;
 }
 
 
 /*
  *        Deletion
  *
  */
 
 static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn)
 {
         if (fn->fn_flags&RTN_ROOT)
                 return net->ipv6.ip6_null_entry;
 
         while(fn) {
                 if(fn->left)
                         return fn->left->leaf;
 
                 if(fn->right)
                         return fn->right->leaf;
 
                 fn = FIB6_SUBTREE(fn);
         }
         return NULL;
 }
 
 /*
  *        Called to trim the tree of intermediate nodes when possible. "fn"
  *        is the node we want to try and remove.
  */
 
 static struct fib6_node *fib6_repair_tree(struct net *net,
                                            struct fib6_node *fn)
 {
         int children;
         int nstate;
         struct fib6_node *child, *pn;
         struct fib6_walker_t *w;
         int iter = 0;
 
         for (;;) {
                 RT6_TRACE("fixing tree: plen=%d iter=%d\n", fn->fn_bit, iter);
                 iter++;
 
                WARN_ON(fn->fn_flags & RTN_RTINFO);
                WARN_ON(fn->fn_flags & RTN_TL_ROOT);
                WARN_ON(fn->leaf != NULL);

                children = 0;
                child = NULL;
                if (fn->right) child = fn->right, children |= 1;
                if (fn->left) child = fn->left, children |= 2;

                if (children == 3 || FIB6_SUBTREE(fn)
#ifdef CONFIG_IPV6_SUBTREES
                    /* Subtree root (i.e. fn) may have one child */
                    || (children && fn->fn_flags&RTN_ROOT)
#endif
                    ) {
                        fn->leaf = fib6_find_prefix(net, fn);
#if RT6_DEBUG >= 2
                        if (fn->leaf==NULL) {
                                WARN_ON(!fn->leaf);
                                fn->leaf = net->ipv6.ip6_null_entry;
                        }
#endif
                        atomic_inc(&fn->leaf->rt6i_ref);
                        return fn->parent;
                }

                pn = fn->parent;
#ifdef CONFIG_IPV6_SUBTREES
                if (FIB6_SUBTREE(pn) == fn) {
                        WARN_ON(!(fn->fn_flags & RTN_ROOT));
                        FIB6_SUBTREE(pn) = NULL;
                        nstate = FWS_L;
                } else {
                        WARN_ON(fn->fn_flags & RTN_ROOT);
#endif
                        if (pn->right == fn) pn->right = child;
                        else if (pn->left == fn) pn->left = child;
#if RT6_DEBUG >= 2
                        else
                                WARN_ON(1);
#endif
                        if (child)
                                child->parent = pn;
                        nstate = FWS_R;
#ifdef CONFIG_IPV6_SUBTREES
                }
#endif

                read_lock(&fib6_walker_lock);
                FOR_WALKERS(w) {
                        if (child == NULL) {
                                if (w->root == fn) {
                                        w->root = w->node = NULL;
                                        RT6_TRACE("W %p adjusted by delroot 1\n", w);
                                } else if (w->node == fn) {
                                        RT6_TRACE("W %p adjusted by delnode 1, s=%d/%d\n", w, w->state, nstate);
                                        w->node = pn;
                                        w->state = nstate;
                                }
                        } else {
                                if (w->root == fn) {
                                        w->root = child;
                                        RT6_TRACE("W %p adjusted by delroot 2\n", w);
                                }
                                if (w->node == fn) {
                                        w->node = child;
                                        if (children&2) {
                                                RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
                                                w->state = w->state>=FWS_R ? FWS_U : FWS_INIT;
                                        } else {
                                                RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
                                                w->state = w->state>=FWS_C ? FWS_U : FWS_INIT;
                                        }
                                }
                        }
                }
                read_unlock(&fib6_walker_lock);

                node_free(fn);
                if (pn->fn_flags&RTN_RTINFO || FIB6_SUBTREE(pn))
                        return pn;

                rt6_release(pn->leaf);
                pn->leaf = NULL;
                fn = pn;
        }
}

static void fib6_del_route(struct fib6_node *fn, struct rt6_info **rtp,
                           struct nl_info *info)
{
        struct fib6_walker_t *w;
        struct rt6_info *rt = *rtp;
        struct net *net = info->nl_net;

        RT6_TRACE("fib6_del_route\n");

        /* Unlink it */
        *rtp = rt->u.dst.rt6_next;
        rt->rt6i_node = NULL;
        net->ipv6.rt6_stats->fib_rt_entries--;
        net->ipv6.rt6_stats->fib_discarded_routes++;

        /* Reset round-robin state, if necessary */
        if (fn->rr_ptr == rt)
                fn->rr_ptr = NULL;

        /* Adjust walkers */
        read_lock(&fib6_walker_lock);
        FOR_WALKERS(w) {
                if (w->state == FWS_C && w->leaf == rt) {
                        RT6_TRACE("walker %p adjusted by delroute\n", w);
                        w->leaf = rt->u.dst.rt6_next;
                        if (w->leaf == NULL)
                                w->state = FWS_U;
                }
        }
        read_unlock(&fib6_walker_lock);

        rt->u.dst.rt6_next = NULL;

        /* If it was last route, expunge its radix tree node */
        if (fn->leaf == NULL) {
                fn->fn_flags &= ~RTN_RTINFO;
                net->ipv6.rt6_stats->fib_route_nodes--;
                fn = fib6_repair_tree(net, fn);
        }

        if (atomic_read(&rt->rt6i_ref) != 1) {
                /* This route is used as dummy address holder in some split
                 * nodes. It is not leaked, but it still holds other resources,
                 * which must be released in time. So, scan ascendant nodes
                 * and replace dummy references to this route with references
                 * to still alive ones.
                 */
                while (fn) {
                        if (!(fn->fn_flags&RTN_RTINFO) && fn->leaf == rt) {
                                fn->leaf = fib6_find_prefix(net, fn);
                                atomic_inc(&fn->leaf->rt6i_ref);
                                rt6_release(rt);
                        }
                        fn = fn->parent;
                }
                /* No more references are possible at this point. */
                BUG_ON(atomic_read(&rt->rt6i_ref) != 1);
        }

        inet6_rt_notify(RTM_DELROUTE, rt, info);
        rt6_release(rt);
}

int fib6_del(struct rt6_info *rt, struct nl_info *info)
{
        struct net *net = info->nl_net;
        struct fib6_node *fn = rt->rt6i_node;
        struct rt6_info **rtp;

#if RT6_DEBUG >= 2
        if (rt->u.dst.obsolete>0) {
                WARN_ON(fn != NULL);
                return -ENOENT;
        }
#endif
        if (fn == NULL || rt == net->ipv6.ip6_null_entry)
                return -ENOENT;

        WARN_ON(!(fn->fn_flags & RTN_RTINFO));

        if (!(rt->rt6i_flags&RTF_CACHE)) {
                struct fib6_node *pn = fn;
#ifdef CONFIG_IPV6_SUBTREES
                /* clones of this route might be in another subtree */
                if (rt->rt6i_src.plen) {
                        while (!(pn->fn_flags&RTN_ROOT))
                                pn = pn->parent;
                        pn = pn->parent;
                }
#endif
                fib6_prune_clones(info->nl_net, pn, rt);
        }

        /*
         *        Walk the leaf entries looking for ourself
         */

        for (rtp = &fn->leaf; *rtp; rtp = &(*rtp)->u.dst.rt6_next) {
                if (*rtp == rt) {
                        fib6_del_route(fn, rtp, info);
                        return 0;
                }
        }
        return -ENOENT;
}

/*
 *        Tree traversal function.
 *
 *        Certainly, it is not interrupt safe.
 *        However, it is internally reenterable wrt itself and fib6_add/fib6_del.
 *        It means, that we can modify tree during walking
 *        and use this function for garbage collection, clone pruning,
 *        cleaning tree when a device goes down etc. etc.
 *
 *        It guarantees that every node will be traversed,
 *        and that it will be traversed only once.
 *
 *        Callback function w->func may return:
 *        0 -> continue walking.
 *        positive value -> walking is suspended (used by tree dumps,
 *        and probably by gc, if it will be split to several slices)
 *        negative value -> terminate walking.
 *
 *        The function itself returns:
 *        0   -> walk is complete.
 *        >0  -> walk is incomplete (i.e. suspended)
 *        <0  -> walk is terminated by an error.
 */

static int fib6_walk_continue(struct fib6_walker_t *w)
{
        struct fib6_node *fn, *pn;

        for (;;) {
                fn = w->node;
                if (fn == NULL)
                        return 0;

                if (w->prune && fn != w->root &&
                    fn->fn_flags&RTN_RTINFO && w->state < FWS_C) {
                        w->state = FWS_C;
                        w->leaf = fn->leaf;
                }
                switch (w->state) {
#ifdef CONFIG_IPV6_SUBTREES
                case FWS_S:
                        if (FIB6_SUBTREE(fn)) {
                                w->node = FIB6_SUBTREE(fn);
                                continue;
                        }
                        w->state = FWS_L;
#endif
                case FWS_L:
                        if (fn->left) {
                                w->node = fn->left;
                                w->state = FWS_INIT;
                                continue;
                        }
                        w->state = FWS_R;
                case FWS_R:
                        if (fn->right) {
                                w->node = fn->right;
                                w->state = FWS_INIT;
                                continue;
                        }
                        w->state = FWS_C;
                        w->leaf = fn->leaf;
                case FWS_C:
                        if (w->leaf && fn->fn_flags&RTN_RTINFO) {
                                int err = w->func(w);
                                if (err)
                                        return err;
                                continue;
                        }
                        w->state = FWS_U;
                case FWS_U:
                        if (fn == w->root)
                                return 0;
                        pn = fn->parent;
                        w->node = pn;
#ifdef CONFIG_IPV6_SUBTREES
                        if (FIB6_SUBTREE(pn) == fn) {
                                WARN_ON(!(fn->fn_flags & RTN_ROOT));
                                w->state = FWS_L;
                                continue;
                        }
#endif
                        if (pn->left == fn) {
                                w->state = FWS_R;
                                continue;
                        }
                        if (pn->right == fn) {
                                w->state = FWS_C;
                                w->leaf = w->node->leaf;
                                continue;
                        }
#if RT6_DEBUG >= 2
                        WARN_ON(1);
#endif
                }
        }
}

static int fib6_walk(struct fib6_walker_t *w)
{
        int res;

        w->state = FWS_INIT;
        w->node = w->root;

        fib6_walker_link(w);
        res = fib6_walk_continue(w);
        if (res <= 0)
                fib6_walker_unlink(w);
        return res;
}

static int fib6_clean_node(struct fib6_walker_t *w)
{
        int res;
        struct rt6_info *rt;
        struct fib6_cleaner_t *c = container_of(w, struct fib6_cleaner_t, w);
        struct nl_info info = {
                .nl_net = c->net,
        };

        for (rt = w->leaf; rt; rt = rt->u.dst.rt6_next) {
                res = c->func(rt, c->arg);
                if (res < 0) {
                        w->leaf = rt;
                        res = fib6_del(rt, &info);
                        if (res) {
#if RT6_DEBUG >= 2
                                printk(KERN_DEBUG "fib6_clean_node: del failed: rt=%p@%p err=%d\n", rt, rt->rt6i_node, res);
#endif
                                continue;
                        }
                        return 0;
                }
                WARN_ON(res != 0);
        }
        w->leaf = rt;
        return 0;
}

/*
 *        Convenient frontend to tree walker.
 *
 *        func is called on each route.
 *                It may return -1 -> delete this route.
 *                              0  -> continue walking
 *
 *        prune==1 -> only immediate children of node (certainly,
 *        ignoring pure split nodes) will be scanned.
 */

static void fib6_clean_tree(struct net *net, struct fib6_node *root,
                            int (*func)(struct rt6_info *, void *arg),
                            int prune, void *arg)
{
        struct fib6_cleaner_t c;

        c.w.root = root;
        c.w.func = fib6_clean_node;
        c.w.prune = prune;
        c.func = func;
        c.arg = arg;
        c.net = net;

        fib6_walk(&c.w);
}

void fib6_clean_all(struct net *net, int (*func)(struct rt6_info *, void *arg),
                    int prune, void *arg)
{
        struct fib6_table *table;
        struct hlist_node *node;
        struct hlist_head *head;
        unsigned int h;

        rcu_read_lock();
        for (h = 0; h < FIB_TABLE_HASHSZ; h++) {
                head = &net->ipv6.fib_table_hash[h];
                hlist_for_each_entry_rcu(table, node, head, tb6_hlist) {
                        write_lock_bh(&table->tb6_lock);
                        fib6_clean_tree(net, &table->tb6_root,
                                        func, prune, arg);
                        write_unlock_bh(&table->tb6_lock);
                }
        }
        rcu_read_unlock();
}

static int fib6_prune_clone(struct rt6_info *rt, void *arg)
{
        if (rt->rt6i_flags & RTF_CACHE) {
                RT6_TRACE("pruning clone %p\n", rt);
                return -1;
        }

        return 0;
}

static void fib6_prune_clones(struct net *net, struct fib6_node *fn,
                              struct rt6_info *rt)
{
        fib6_clean_tree(net, fn, fib6_prune_clone, 1, rt);
}

/*
 *        Garbage collection
 */

static struct fib6_gc_args
{
        int                        timeout;
        int                        more;
} gc_args;

static int fib6_age(struct rt6_info *rt, void *arg)
{
        unsigned long now = jiffies;

        /*
         *        check addrconf expiration here.
         *        Routes are expired even if they are in use.
         *
         *        Also age clones. Note, that clones are aged out
         *        only if they are not in use now.
         */

        if (rt->rt6i_flags&RTF_EXPIRES && rt->rt6i_expires) {
                if (time_after(now, rt->rt6i_expires)) {
                        RT6_TRACE("expiring %p\n", rt);
                        return -1;
                }
                gc_args.more++;
        } else if (rt->rt6i_flags & RTF_CACHE) {
                if (atomic_read(&rt->u.dst.__refcnt) == 0 &&
                    time_after_eq(now, rt->u.dst.lastuse + gc_args.timeout)) {
                        RT6_TRACE("aging clone %p\n", rt);
                        return -1;
                } else if ((rt->rt6i_flags & RTF_GATEWAY) &&
                           (!(rt->rt6i_nexthop->flags & NTF_ROUTER))) {
                        RT6_TRACE("purging route %p via non-router but gateway\n",
                                  rt);
                        return -1;
                }
                gc_args.more++;
        }

        return 0;
}

static DEFINE_SPINLOCK(fib6_gc_lock);

void fib6_run_gc(unsigned long expires, struct net *net)
{
        if (expires != ~0UL) {
                spin_lock_bh(&fib6_gc_lock);
                gc_args.timeout = expires ? (int)expires :
                        net->ipv6.sysctl.ip6_rt_gc_interval;
        } else {
                if (!spin_trylock_bh(&fib6_gc_lock)) {
                        mod_timer(&net->ipv6.ip6_fib_timer, jiffies + HZ);
                        return;
                }
                gc_args.timeout = net->ipv6.sysctl.ip6_rt_gc_interval;
        }

        gc_args.more = icmp6_dst_gc();

        fib6_clean_all(net, fib6_age, 0, NULL);

        if (gc_args.more)
                mod_timer(&net->ipv6.ip6_fib_timer,
                          round_jiffies(jiffies
                                        + net->ipv6.sysctl.ip6_rt_gc_interval));
        else
                del_timer(&net->ipv6.ip6_fib_timer);
        spin_unlock_bh(&fib6_gc_lock);
}

static void fib6_gc_timer_cb(unsigned long arg)
{
        fib6_run_gc(0, (struct net *)arg);
}

static int fib6_net_init(struct net *net)
{
        setup_timer(&net->ipv6.ip6_fib_timer, fib6_gc_timer_cb, (unsigned long)net);

        net->ipv6.rt6_stats = kzalloc(sizeof(*net->ipv6.rt6_stats), GFP_KERNEL);
        if (!net->ipv6.rt6_stats)
                goto out_timer;

        net->ipv6.fib_table_hash = kcalloc(FIB_TABLE_HASHSZ,
                                           sizeof(*net->ipv6.fib_table_hash),
                                           GFP_KERNEL);
        if (!net->ipv6.fib_table_hash)
                goto out_rt6_stats;

        net->ipv6.fib6_main_tbl = kzalloc(sizeof(*net->ipv6.fib6_main_tbl),
                                          GFP_KERNEL);
        if (!net->ipv6.fib6_main_tbl)
                goto out_fib_table_hash;

        net->ipv6.fib6_main_tbl->tb6_id = RT6_TABLE_MAIN;
        net->ipv6.fib6_main_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;
        net->ipv6.fib6_main_tbl->tb6_root.fn_flags =
                RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;

#ifdef CONFIG_IPV6_MULTIPLE_TABLES
        net->ipv6.fib6_local_tbl = kzalloc(sizeof(*net->ipv6.fib6_local_tbl),
                                           GFP_KERNEL);
        if (!net->ipv6.fib6_local_tbl)
                goto out_fib6_main_tbl;
        net->ipv6.fib6_local_tbl->tb6_id = RT6_TABLE_LOCAL;
        net->ipv6.fib6_local_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;
        net->ipv6.fib6_local_tbl->tb6_root.fn_flags =
                RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
#endif
        fib6_tables_init(net);

        return 0;

#ifdef CONFIG_IPV6_MULTIPLE_TABLES
out_fib6_main_tbl:
        kfree(net->ipv6.fib6_main_tbl);
#endif
out_fib_table_hash:
        kfree(net->ipv6.fib_table_hash);
out_rt6_stats:
        kfree(net->ipv6.rt6_stats);
out_timer:
        return -ENOMEM;
 }

static void fib6_net_exit(struct net *net)
{
        rt6_ifdown(net, NULL);
        del_timer_sync(&net->ipv6.ip6_fib_timer);

#ifdef CONFIG_IPV6_MULTIPLE_TABLES
        kfree(net->ipv6.fib6_local_tbl);
#endif
        kfree(net->ipv6.fib6_main_tbl);
        kfree(net->ipv6.fib_table_hash);
        kfree(net->ipv6.rt6_stats);
}

static struct pernet_operations fib6_net_ops = {
        .init = fib6_net_init,
        .exit = fib6_net_exit,
};

int __init fib6_init(void)
{
        int ret = -ENOMEM;

        fib6_node_kmem = kmem_cache_create("fib6_nodes",
                                           sizeof(struct fib6_node),
                                           0, SLAB_HWCACHE_ALIGN,
                                           NULL);
        if (!fib6_node_kmem)
                goto out;

        ret = register_pernet_subsys(&fib6_net_ops);
        if (ret)
                goto out_kmem_cache_create;

        ret = __rtnl_register(PF_INET6, RTM_GETROUTE, NULL, inet6_dump_fib);
        if (ret)
                goto out_unregister_subsys;
out:
        return ret;

out_unregister_subsys:
        unregister_pernet_subsys(&fib6_net_ops);
out_kmem_cache_create:
        kmem_cache_destroy(fib6_node_kmem);
        goto out;
}

void fib6_gc_cleanup(void)
{
        unregister_pernet_subsys(&fib6_net_ops);
        kmem_cache_destroy(fib6_node_kmem);
}