1 files changed, 107 insertions, 58 deletions

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index bf727149fdec..02c16909f618 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -249,40 +249,52 @@ static struct fib6_table *fib6_alloc_table(struct net *net, u32 id)
 
 struct fib6_table *fib6_new_table(struct net *net, u32 id)
 {
-	struct fib6_table *tb;
+	struct fib6_table *tb, *new_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)
-		fib6_link_table(net, tb);
+	new_tb = fib6_alloc_table(net, id);
+	if (!new_tb)
+		return NULL;
+
+	spin_lock_bh(&net->ipv6.fib_table_hash_lock);
+
+	tb = fib6_get_table(net, id);
+	if (unlikely(tb)) {
+		spin_unlock_bh(&net->ipv6.fib_table_hash_lock);
+		kfree(new_tb);
+		return tb;
+	}
 
-	return tb;
+	fib6_link_table(net, new_tb);
+
+	spin_unlock_bh(&net->ipv6.fib_table_hash_lock);
+
+	return new_tb;
 }
 EXPORT_SYMBOL_GPL(fib6_new_table);
 
 struct fib6_table *fib6_get_table(struct net *net, u32 id)
 {
-	struct fib6_table *tb;
 	struct hlist_head *head;
-	unsigned int h;
+	struct fib6_table *tb;
 
-	if (id == 0)
+	if (!id)
 		id = RT6_TABLE_MAIN;
-	h = id & (FIB6_TABLE_HASHSZ - 1);
-	rcu_read_lock();
-	head = &net->ipv6.fib_table_hash[h];
-	hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
-		if (tb->tb6_id == id) {
-			rcu_read_unlock();
+
+	head = &net->ipv6.fib_table_hash[id & (FIB6_TABLE_HASHSZ - 1)];
+
+	/* See comment in fib6_link_table().  RCU is not required,
+	 * but rcu_dereference_raw() is used to avoid data-race.
+	 */
+	hlist_for_each_entry_rcu(tb, head, tb6_hlist, true)
+		if (tb->tb6_id == id)
 			return tb;
-		}
-	}
-	rcu_read_unlock();
 
 	return NULL;
 }
@@ -433,15 +445,17 @@ struct fib6_dump_arg {
 static int fib6_rt_dump(struct fib6_info *rt, struct fib6_dump_arg *arg)
 {
 	enum fib_event_type fib_event = FIB_EVENT_ENTRY_REPLACE;
+	unsigned int nsiblings;
 	int err;
 
 	if (!rt || rt == arg->net->ipv6.fib6_null_entry)
 		return 0;
 
-	if (rt->fib6_nsiblings)
+	nsiblings = READ_ONCE(rt->fib6_nsiblings);
+	if (nsiblings)
 		err = call_fib6_multipath_entry_notifier(arg->nb, fib_event,
 							 rt,
-							 rt->fib6_nsiblings,
+							 nsiblings,
 							 arg->extack);
 	else
 		err = call_fib6_entry_notifier(arg->nb, fib_event, rt,
@@ -951,8 +965,7 @@ insert_above:
 }
 
 static void __fib6_drop_pcpu_from(struct fib6_nh *fib6_nh,
-				  const struct fib6_info *match,
-				  const struct fib6_table *table)
+				  const struct fib6_info *match)
 {
 	int cpu;
 
@@ -987,21 +1000,15 @@ static void __fib6_drop_pcpu_from(struct fib6_nh *fib6_nh,
 	rcu_read_unlock();
 }
 
-struct fib6_nh_pcpu_arg {
-	struct fib6_info	*from;
-	const struct fib6_table *table;
-};
-
 static int fib6_nh_drop_pcpu_from(struct fib6_nh *nh, void *_arg)
 {
-	struct fib6_nh_pcpu_arg *arg = _arg;
+	struct fib6_info *arg = _arg;
 
-	__fib6_drop_pcpu_from(nh, arg->from, arg->table);
+	__fib6_drop_pcpu_from(nh, arg);
 	return 0;
 }
 
-static void fib6_drop_pcpu_from(struct fib6_info *f6i,
-				const struct fib6_table *table)
+static void fib6_drop_pcpu_from(struct fib6_info *f6i)
 {
 	/* Make sure rt6_make_pcpu_route() wont add other percpu routes
 	 * while we are cleaning them here.
@@ -1010,18 +1017,14 @@ static void fib6_drop_pcpu_from(struct fib6_info *f6i,
 	mb(); /* paired with the cmpxchg() in rt6_make_pcpu_route() */
 
 	if (f6i->nh) {
-		struct fib6_nh_pcpu_arg arg = {
-			.from = f6i,
-			.table = table
-		};
-
-		nexthop_for_each_fib6_nh(f6i->nh, fib6_nh_drop_pcpu_from,
-					 &arg);
+		rcu_read_lock();
+		nexthop_for_each_fib6_nh(f6i->nh, fib6_nh_drop_pcpu_from, f6i);
+		rcu_read_unlock();
 	} else {
 		struct fib6_nh *fib6_nh;
 
 		fib6_nh = f6i->fib6_nh;
-		__fib6_drop_pcpu_from(fib6_nh, f6i, table);
+		__fib6_drop_pcpu_from(fib6_nh, f6i);
 	}
 }
 
@@ -1032,10 +1035,16 @@ static void fib6_purge_rt(struct fib6_info *rt, struct fib6_node *fn,
 
 	/* Flush all cached dst in exception table */
 	rt6_flush_exceptions(rt);
-	fib6_drop_pcpu_from(rt, table);
+	fib6_drop_pcpu_from(rt);
+
+	if (rt->nh) {
+		spin_lock(&rt->nh->lock);
+
+		if (!list_empty(&rt->nh_list))
+			list_del_init(&rt->nh_list);
 
-	if (rt->nh && !list_empty(&rt->nh_list))
-		list_del_init(&rt->nh_list);
+		spin_unlock(&rt->nh->lock);
+	}
 
 	if (refcount_read(&rt->fib6_ref) != 1) {
 		/* This route is used as dummy address holder in some split
@@ -1069,8 +1078,8 @@ static void fib6_purge_rt(struct fib6_info *rt, struct fib6_node *fn,
  */
 
 static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
-			    struct nl_info *info,
-			    struct netlink_ext_ack *extack)
+			    struct nl_info *info, struct netlink_ext_ack *extack,
+			    struct list_head *purge_list)
 {
 	struct fib6_info *leaf = rcu_dereference_protected(fn->leaf,
 				    lockdep_is_held(&rt->fib6_table->tb6_lock));
@@ -1119,7 +1128,7 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
 
 			if (rt6_duplicate_nexthop(iter, rt)) {
 				if (rt->fib6_nsiblings)
-					rt->fib6_nsiblings = 0;
+					WRITE_ONCE(rt->fib6_nsiblings, 0);
 				if (!(iter->fib6_flags & RTF_EXPIRES))
 					return -EEXIST;
 				if (!(rt->fib6_flags & RTF_EXPIRES)) {
@@ -1148,7 +1157,8 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
 			 */
 			if (rt_can_ecmp &&
 			    rt6_qualify_for_ecmp(iter))
-				rt->fib6_nsiblings++;
+				WRITE_ONCE(rt->fib6_nsiblings,
+					   rt->fib6_nsiblings + 1);
 		}
 
 		if (iter->fib6_metric > rt->fib6_metric)
@@ -1198,12 +1208,15 @@ next_iter:
 		fib6_nsiblings = 0;
 		list_for_each_entry_safe(sibling, temp_sibling,
 					 &rt->fib6_siblings, fib6_siblings) {
-			sibling->fib6_nsiblings++;
+			WRITE_ONCE(sibling->fib6_nsiblings,
+				   sibling->fib6_nsiblings + 1);
 			BUG_ON(sibling->fib6_nsiblings != rt->fib6_nsiblings);
 			fib6_nsiblings++;
 		}
 		BUG_ON(fib6_nsiblings != rt->fib6_nsiblings);
+		rcu_read_lock();
 		rt6_multipath_rebalance(temp_sibling);
+		rcu_read_unlock();
 	}
 
 	/*
@@ -1243,10 +1256,13 @@ add:
 				list_for_each_entry_safe(sibling, next_sibling,
 							 &rt->fib6_siblings,
 							 fib6_siblings)
-					sibling->fib6_nsiblings--;
-				rt->fib6_nsiblings = 0;
+					WRITE_ONCE(sibling->fib6_nsiblings,
+						   sibling->fib6_nsiblings - 1);
+				WRITE_ONCE(rt->fib6_nsiblings, 0);
 				list_del_rcu(&rt->fib6_siblings);
+				rcu_read_lock();
 				rt6_multipath_rebalance(next_sibling);
+				rcu_read_unlock();
 				return err;
 			}
 		}
@@ -1294,10 +1310,9 @@ add:
 		}
 		nsiblings = iter->fib6_nsiblings;
 		iter->fib6_node = NULL;
-		fib6_purge_rt(iter, fn, info->nl_net);
+		list_add(&iter->purge_link, purge_list);
 		if (rcu_access_pointer(fn->rr_ptr) == iter)
 			fn->rr_ptr = NULL;
-		fib6_info_release(iter);
 
 		if (nsiblings) {
 			/* Replacing an ECMP route, remove all siblings */
@@ -1310,10 +1325,9 @@ add:
 				if (rt6_qualify_for_ecmp(iter)) {
 					*ins = iter->fib6_next;
 					iter->fib6_node = NULL;
-					fib6_purge_rt(iter, fn, info->nl_net);
+					list_add(&iter->purge_link, purge_list);
 					if (rcu_access_pointer(fn->rr_ptr) == iter)
 						fn->rr_ptr = NULL;
-					fib6_info_release(iter);
 					nsiblings--;
 					info->nl_net->ipv6.rt6_stats->fib_rt_entries--;
 				} else {
@@ -1329,6 +1343,28 @@ add:
 	return 0;
 }
 
+static int fib6_add_rt2node_nh(struct fib6_node *fn, struct fib6_info *rt,
+			       struct nl_info *info, struct netlink_ext_ack *extack,
+			       struct list_head *purge_list)
+{
+	int err;
+
+	spin_lock(&rt->nh->lock);
+
+	if (rt->nh->dead) {
+		NL_SET_ERR_MSG(extack, "Nexthop has been deleted");
+		err = -EINVAL;
+	} else {
+		err = fib6_add_rt2node(fn, rt, info, extack, purge_list);
+		if (!err)
+			list_add(&rt->nh_list, &rt->nh->f6i_list);
+	}
+
+	spin_unlock(&rt->nh->lock);
+
+	return err;
+}
+
 static void fib6_start_gc(struct net *net, struct fib6_info *rt)
 {
 	if (!timer_pending(&net->ipv6.ip6_fib_timer) &&
@@ -1383,6 +1419,7 @@ int fib6_add(struct fib6_node *root, struct fib6_info *rt,
 	     struct nl_info *info, struct netlink_ext_ack *extack)
 {
 	struct fib6_table *table = rt->fib6_table;
+	LIST_HEAD(purge_list);
 	struct fib6_node *fn;
 #ifdef CONFIG_IPV6_SUBTREES
 	struct fib6_node *pn = NULL;
@@ -1485,10 +1522,19 @@ int fib6_add(struct fib6_node *root, struct fib6_info *rt,
 	}
 #endif
 
-	err = fib6_add_rt2node(fn, rt, info, extack);
+	if (rt->nh)
+		err = fib6_add_rt2node_nh(fn, rt, info, extack, &purge_list);
+	else
+		err = fib6_add_rt2node(fn, rt, info, extack, &purge_list);
 	if (!err) {
-		if (rt->nh)
-			list_add(&rt->nh_list, &rt->nh->f6i_list);
+		struct fib6_info *iter, *next;
+
+		list_for_each_entry_safe(iter, next, &purge_list, purge_link) {
+			list_del(&iter->purge_link);
+			fib6_purge_rt(iter, fn, info->nl_net);
+			fib6_info_release(iter);
+		}
+
 		__fib6_update_sernum_upto_root(rt, fib6_new_sernum(info->nl_net));
 
 		if (rt->fib6_flags & RTF_EXPIRES)
@@ -1961,8 +2007,9 @@ static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn,
 			notify_del = true;
 		list_for_each_entry_safe(sibling, next_sibling,
 					 &rt->fib6_siblings, fib6_siblings)
-			sibling->fib6_nsiblings--;
-		rt->fib6_nsiblings = 0;
+			WRITE_ONCE(sibling->fib6_nsiblings,
+				   sibling->fib6_nsiblings - 1);
+		WRITE_ONCE(rt->fib6_nsiblings, 0);
 		list_del_rcu(&rt->fib6_siblings);
 		rt6_multipath_rebalance(next_sibling);
 	}
@@ -2389,7 +2436,7 @@ void fib6_run_gc(unsigned long expires, struct net *net, bool force)
 
 static void fib6_gc_timer_cb(struct timer_list *t)
 {
-	struct net *arg = from_timer(arg, t, ipv6.ip6_fib_timer);
+	struct net *arg = timer_container_of(arg, t, ipv6.ip6_fib_timer);
 
 	fib6_run_gc(0, arg, true);
 }
@@ -2423,6 +2470,8 @@ static int __net_init fib6_net_init(struct net *net)
 	if (!net->ipv6.fib_table_hash)
 		goto out_rt6_stats;
 
+	spin_lock_init(&net->ipv6.fib_table_hash_lock);
+
 	net->ipv6.fib6_main_tbl = kzalloc(sizeof(*net->ipv6.fib6_main_tbl),
 					  GFP_KERNEL);
 	if (!net->ipv6.fib6_main_tbl)