[PATCH][3.13.y-ckt][PATCH 1/1] bridge: Fix the way to find old local fdb entries in br_fdb_changeaddr
From: Joseph Salisbury
Date: Fri May 20 2016 - 13:01:07 EST
From: Toshiaki Makita <makita.toshiaki@xxxxxxxxxxxxx>
BugLink: http://bugs.launchpad.net/bugs/1581585
br_fdb_changeaddr() assumes that there is at most one local entry per port
per vlan. It used to be true, but since commit 36fd2b63e3b4 ("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: Toshiaki Makita <makita.toshiaki@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
(backported from commit a5642ab4744bc8c5a8c7ce7c6e30c01bd6bbc691)
Signed-off-by: Joseph Salisbury <joseph.salisbury@xxxxxxxxxxxxx>
---
net/bridge/br_fdb.c | 16 ++++++++++++----
net/bridge/br_input.c | 8 ++++----
net/bridge/br_private.h | 3 ++-
3 files changed, 18 insertions(+), 9 deletions(-)
diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index 62c444d..551a27d 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -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;
@@ -473,13 +475,18 @@ 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
@@ -648,6 +655,7 @@ 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) {
@@ -666,7 +674,7 @@ static int __br_fdb_add(struct ndmsg *ndm, struct net_bridge_port *p,
if (ndm->ndm_flags & NTF_USE) {
local_bh_disable();
rcu_read_lock();
- br_fdb_update(p->br, p, addr, vid);
+ br_fdb_update(p->br, p, addr, vid, true);
rcu_read_unlock();
local_bh_enable();
} else {
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 2bc64f8..ab0ee7d 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -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))
@@ -146,9 +146,9 @@ static int br_handle_local_finish(struct sk_buff *skb)
struct net_bridge_port *p = br_port_get_rcu(skb->dev);
u16 vid = 0;
- /* check if vlan is allowed, to avoid spoofing */
- if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid))
- br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid);
+ br_vlan_get_tag(skb, &vid);
+ if (p->flags & BR_LEARNING)
+ br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false);
return 0; /* process further */
}
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 59788d6..a932c46 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -105,6 +105,7 @@ struct net_bridge_fdb_entry
mac_addr addr;
unsigned char is_local;
unsigned char is_static;
+ unsigned char added_by_user;
__u16 vlan_id;
};
@@ -398,7 +399,7 @@ 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[],
--
2.7.4