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Commit a5642ab4 authored by Toshiaki Makita's avatar Toshiaki Makita Committed by David S. Miller
Browse files

bridge: Fix the way to find old local fdb entries in br_fdb_changeaddr 



br_fdb_changeaddr() assumes that there is at most one local entry per port
per vlan. It used to be true, but since commit 36fd2b63 ("bridge: allow
creating/deleting fdb entries via netlink"), it has not been so.
Therefore, the function might fail to search a correct previous address
to be deleted and delete an arbitrary local entry if user has added local
entries manually.

Example of problematic case:
  ip link set eth0 address ee:ff:12:34:56:78
  brctl addif br0 eth0
  bridge fdb add 12:34:56:78:90:ab dev eth0 master
  ip link set eth0 address aa:bb:cc:dd:ee:ff
Then, the address 12:34:56:78:90:ab might be deleted instead of
ee:ff:12:34:56:78, the original mac address of eth0.

Address this issue by introducing a new flag, added_by_user, to struct
net_bridge_fdb_entry.

Note that br_fdb_delete_by_port() has to set added_by_user to 0 in cases
like:
  ip link set eth0 address 12:34:56:78:90:ab
  ip link set eth1 address aa:bb:cc:dd:ee:ff
  brctl addif br0 eth0
  bridge fdb add aa:bb:cc:dd:ee:ff dev eth0 master
  brctl addif br0 eth1
  brctl delif br0 eth0
In this case, kernel should delete the user-added entry aa:bb:cc:dd:ee:ff,
but it also should have been added by "brctl addif br0 eth1" originally,
so we don't delete it and treat it a new kernel-created entry.

Signed-off-by: default avatarToshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b10bd54c

net/bridge/br_fdb.c

+12 −4
Original line number Diff line number Diff line
@@ -104,7 +104,7 @@ void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr) 
			struct net_bridge_fdb_entry *f;



			f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);

			if (f->dst == p && f->is_local) {

			if (f->dst == p && f->is_local && !f->added_by_user) {

				/* maybe another port has same hw addr? */

				struct net_bridge_port *op;

				u16 vid = f->vlan_id;
@@ -247,6 +247,7 @@ void br_fdb_delete_by_port(struct net_bridge *br, 
					    ether_addr_equal(op->dev->dev_addr,

							     f->addr.addr)) {

						f->dst = op;

						f->added_by_user = 0;

						goto skip_delete;

					}

				}
@@ -397,6 +398,7 @@ static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head, 
		fdb->vlan_id = vid;

		fdb->is_local = 0;

		fdb->is_static = 0;

		fdb->added_by_user = 0;

		fdb->updated = fdb->used = jiffies;

		hlist_add_head_rcu(&fdb->hlist, head);

	}
@@ -447,7 +449,7 @@ int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source, 
}



void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,

		   const unsigned char *addr, u16 vid)

		   const unsigned char *addr, u16 vid, bool added_by_user)

{

	struct hlist_head *head = &br->hash[br_mac_hash(addr, vid)];

	struct net_bridge_fdb_entry *fdb;
@@ -473,14 +475,19 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source, 
			/* fastpath: update of existing entry */

			fdb->dst = source;

			fdb->updated = jiffies;

			if (unlikely(added_by_user))

				fdb->added_by_user = 1;

		}

	} else {

		spin_lock(&br->hash_lock);

		if (likely(!fdb_find(head, addr, vid))) {

			fdb = fdb_create(head, source, addr, vid);

			if (fdb)

			if (fdb) {

				if (unlikely(added_by_user))

					fdb->added_by_user = 1;

				fdb_notify(br, fdb, RTM_NEWNEIGH);

			}

		}

		/* else  we lose race and someone else inserts

		 * it first, don't bother updating

		 */
@@ -647,6 +654,7 @@ static int fdb_add_entry(struct net_bridge_port *source, const __u8 *addr, 


		modified = true;

	}

	fdb->added_by_user = 1;



	fdb->used = jiffies;

	if (modified) {
@@ -664,7 +672,7 @@ static int __br_fdb_add(struct ndmsg *ndm, struct net_bridge_port *p, 


	if (ndm->ndm_flags & NTF_USE) {

		rcu_read_lock();

		br_fdb_update(p->br, p, addr, vid);

		br_fdb_update(p->br, p, addr, vid, true);

		rcu_read_unlock();

	} else {

		spin_lock_bh(&p->br->hash_lock);

net/bridge/br_input.c

+2 −2
Original line number Diff line number Diff line
@@ -77,7 +77,7 @@ int br_handle_frame_finish(struct sk_buff *skb) 
	/* insert into forwarding database after filtering to avoid spoofing */

	br = p->br;

	if (p->flags & BR_LEARNING)

		br_fdb_update(br, p, eth_hdr(skb)->h_source, vid);

		br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false);



	if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) &&

	    br_multicast_rcv(br, p, skb, vid))
@@ -148,7 +148,7 @@ static int br_handle_local_finish(struct sk_buff *skb) 


	br_vlan_get_tag(skb, &vid);

	if (p->flags & BR_LEARNING)

		br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid);

		br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false);

	return 0;	 /* process further */

}

net/bridge/br_private.h

+2 −1
Original line number Diff line number Diff line
@@ -104,6 +104,7 @@ struct net_bridge_fdb_entry 
	mac_addr			addr;

	unsigned char			is_local;

	unsigned char			is_static;

	unsigned char			added_by_user;

	__u16				vlan_id;

};
@@ -383,7 +384,7 @@ int br_fdb_fillbuf(struct net_bridge *br, void *buf, unsigned long count, 
int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,

		  const unsigned char *addr, u16 vid);

void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,

		   const unsigned char *addr, u16 vid);

		   const unsigned char *addr, u16 vid, bool added_by_user);

int fdb_delete_by_addr(struct net_bridge *br, const u8 *addr, u16 vid);



int br_fdb_delete(struct ndmsg *ndm, struct nlattr *tb[],