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authorDavid S. Miller <davem@davemloft.net>2021-06-10 14:06:43 -0700
committerDavid S. Miller <davem@davemloft.net>2021-06-10 14:06:43 -0700
commit172947ac678e426cc8eb0e4107017d1fb38c6037 (patch)
tree15eb00d6b79d73c4eb064f8942acf9a0e20a436c
parent9d44fa3e50cc91691896934d106c86e4027e61ca (diff)
parentcfc579f9d89af4ada58c69b03bcaa4887840f3b3 (diff)
Merge branch 'bridge-egress-fixes'
Nikolay Aleksandrov says: ==================== net: bridge: vlan tunnel egress path fixes These two fixes take care of tunnel_dst problems in the vlan tunnel egress path. Patch 01 fixes a null ptr deref due to the lockless use of tunnel_dst pointer without checking it first, and patch 02 fixes a use-after-free issue due to wrong dst refcounting (dst_clone() -> dst_hold_safe()). Both fix the same commit and should be queued for stable backports: Fixes: 11538d039ac6 ("bridge: vlan dst_metadata hooks in ingress and egress paths") v2: no changes, added stable list to CC ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/bridge/br_private.h4
-rw-r--r--net/bridge/br_vlan_tunnel.c38
2 files changed, 26 insertions, 16 deletions
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 7ce8a77cc6b6..e013d33f1c7c 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -90,8 +90,8 @@ struct bridge_mcast_stats {
#endif
struct br_tunnel_info {
- __be64 tunnel_id;
- struct metadata_dst *tunnel_dst;
+ __be64 tunnel_id;
+ struct metadata_dst __rcu *tunnel_dst;
};
/* private vlan flags */
diff --git a/net/bridge/br_vlan_tunnel.c b/net/bridge/br_vlan_tunnel.c
index 0d3a8c01552e..01017448ebde 100644
--- a/net/bridge/br_vlan_tunnel.c
+++ b/net/bridge/br_vlan_tunnel.c
@@ -41,26 +41,33 @@ static struct net_bridge_vlan *br_vlan_tunnel_lookup(struct rhashtable *tbl,
br_vlan_tunnel_rht_params);
}
+static void vlan_tunnel_info_release(struct net_bridge_vlan *vlan)
+{
+ struct metadata_dst *tdst = rtnl_dereference(vlan->tinfo.tunnel_dst);
+
+ WRITE_ONCE(vlan->tinfo.tunnel_id, 0);
+ RCU_INIT_POINTER(vlan->tinfo.tunnel_dst, NULL);
+ dst_release(&tdst->dst);
+}
+
void vlan_tunnel_info_del(struct net_bridge_vlan_group *vg,
struct net_bridge_vlan *vlan)
{
- if (!vlan->tinfo.tunnel_dst)
+ if (!rcu_access_pointer(vlan->tinfo.tunnel_dst))
return;
rhashtable_remove_fast(&vg->tunnel_hash, &vlan->tnode,
br_vlan_tunnel_rht_params);
- vlan->tinfo.tunnel_id = 0;
- dst_release(&vlan->tinfo.tunnel_dst->dst);
- vlan->tinfo.tunnel_dst = NULL;
+ vlan_tunnel_info_release(vlan);
}
static int __vlan_tunnel_info_add(struct net_bridge_vlan_group *vg,
struct net_bridge_vlan *vlan, u32 tun_id)
{
- struct metadata_dst *metadata = NULL;
+ struct metadata_dst *metadata = rtnl_dereference(vlan->tinfo.tunnel_dst);
__be64 key = key32_to_tunnel_id(cpu_to_be32(tun_id));
int err;
- if (vlan->tinfo.tunnel_dst)
+ if (metadata)
return -EEXIST;
metadata = __ip_tun_set_dst(0, 0, 0, 0, 0, TUNNEL_KEY,
@@ -69,8 +76,8 @@ static int __vlan_tunnel_info_add(struct net_bridge_vlan_group *vg,
return -EINVAL;
metadata->u.tun_info.mode |= IP_TUNNEL_INFO_TX | IP_TUNNEL_INFO_BRIDGE;
- vlan->tinfo.tunnel_dst = metadata;
- vlan->tinfo.tunnel_id = key;
+ rcu_assign_pointer(vlan->tinfo.tunnel_dst, metadata);
+ WRITE_ONCE(vlan->tinfo.tunnel_id, key);
err = rhashtable_lookup_insert_fast(&vg->tunnel_hash, &vlan->tnode,
br_vlan_tunnel_rht_params);
@@ -79,9 +86,7 @@ static int __vlan_tunnel_info_add(struct net_bridge_vlan_group *vg,
return 0;
out:
- dst_release(&vlan->tinfo.tunnel_dst->dst);
- vlan->tinfo.tunnel_dst = NULL;
- vlan->tinfo.tunnel_id = 0;
+ vlan_tunnel_info_release(vlan);
return err;
}
@@ -182,12 +187,15 @@ int br_handle_ingress_vlan_tunnel(struct sk_buff *skb,
int br_handle_egress_vlan_tunnel(struct sk_buff *skb,
struct net_bridge_vlan *vlan)
{
+ struct metadata_dst *tunnel_dst;
+ __be64 tunnel_id;
int err;
- if (!vlan || !vlan->tinfo.tunnel_id)
+ if (!vlan)
return 0;
- if (unlikely(!skb_vlan_tag_present(skb)))
+ tunnel_id = READ_ONCE(vlan->tinfo.tunnel_id);
+ if (!tunnel_id || unlikely(!skb_vlan_tag_present(skb)))
return 0;
skb_dst_drop(skb);
@@ -195,7 +203,9 @@ int br_handle_egress_vlan_tunnel(struct sk_buff *skb,
if (err)
return err;
- skb_dst_set(skb, dst_clone(&vlan->tinfo.tunnel_dst->dst));
+ tunnel_dst = rcu_dereference(vlan->tinfo.tunnel_dst);
+ if (tunnel_dst && dst_hold_safe(&tunnel_dst->dst))
+ skb_dst_set(skb, &tunnel_dst->dst);
return 0;
}