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Commit c18865f3 authored by Julian Anastasov's avatar Julian Anastasov Committed by David S. Miller
Browse files

[IPV4] fib: fix route replacement, fib_info is shared 



fib_info can be shared by many route prefixes but we don't want
duplicate alternative routes for a prefix+tos+priority. Last change
was not correct to check fib_treeref because it accounts usage from
other prefixes. Additionally, avoid replacement without error if new
route is same, as Joonwoo Park suggests.

Signed-off-by: default avatarJulian Anastasov <ja@ssi.bg>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ec9dbb1c

net/ipv4/fib_hash.c

+31 −16
Original line number Diff line number Diff line
@@ -424,19 +424,43 @@ static int fn_hash_insert(struct fib_table *tb, struct fib_config *cfg) 


	if (fa && fa->fa_tos == tos &&

	    fa->fa_info->fib_priority == fi->fib_priority) {

		struct fib_alias *fa_orig;

		struct fib_alias *fa_first, *fa_match;



		err = -EEXIST;

		if (cfg->fc_nlflags & NLM_F_EXCL)

			goto out;



		/* We have 2 goals:

		 * 1. Find exact match for type, scope, fib_info to avoid

		 * duplicate routes

		 * 2. Find next 'fa' (or head), NLM_F_APPEND inserts before it

		 */

		fa_match = NULL;

		fa_first = fa;

		fa = list_entry(fa->fa_list.prev, struct fib_alias, fa_list);

		list_for_each_entry_continue(fa, &f->fn_alias, fa_list) {

			if (fa->fa_tos != tos)

				break;

			if (fa->fa_info->fib_priority != fi->fib_priority)

				break;

			if (fa->fa_type == cfg->fc_type &&

			    fa->fa_scope == cfg->fc_scope &&

			    fa->fa_info == fi) {

				fa_match = fa;

				break;

			}

		}



		if (cfg->fc_nlflags & NLM_F_REPLACE) {

			struct fib_info *fi_drop;

			u8 state;



			if (fi->fib_treeref > 1)

			fa = fa_first;

			if (fa_match) {

				if (fa == fa_match)

					err = 0;

				goto out;



			}

			write_lock_bh(&fib_hash_lock);

			fi_drop = fa->fa_info;

			fa->fa_info = fi;
@@ -459,20 +483,11 @@ static int fn_hash_insert(struct fib_table *tb, struct fib_config *cfg) 
		 * uses the same scope, type, and nexthop

		 * information.

		 */

		fa_orig = fa;

		fa = list_entry(fa->fa_list.prev, struct fib_alias, fa_list);

		list_for_each_entry_continue(fa, &f->fn_alias, fa_list) {

			if (fa->fa_tos != tos)

				break;

			if (fa->fa_info->fib_priority != fi->fib_priority)

				break;

			if (fa->fa_type == cfg->fc_type &&

			    fa->fa_scope == cfg->fc_scope &&

			    fa->fa_info == fi)

		if (fa_match)

			goto out;

		}



		if (!(cfg->fc_nlflags & NLM_F_APPEND))

			fa = fa_orig;

			fa = fa_first;

	}



	err = -ENOENT;