net/bridge: Update br_mdb_dump for strict data checking

Update br_mdb_dump for strict data checking. If the flag is set,
the dump request is expected to have a br_port_msg struct as the
header. All elements of the struct are expected to be 0 and no
attributes can be appended.

Signed-off-by: David Ahern <dsahern@gmail.com>
Acked-by: Christian Brauner <christian@brauner.io>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index a4a848b..a7ea2d4 100644 (file)
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -162,6 +162,29 @@ out:
        return err;
 }
 
+static int br_mdb_valid_dump_req(const struct nlmsghdr *nlh,
+                                struct netlink_ext_ack *extack)
+{
+       struct br_port_msg *bpm;
+
+       if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*bpm))) {
+               NL_SET_ERR_MSG_MOD(extack, "Invalid header for mdb dump request");
+               return -EINVAL;
+       }
+
+       bpm = nlmsg_data(nlh);
+       if (bpm->ifindex) {
+               NL_SET_ERR_MSG_MOD(extack, "Filtering by device index is not supported for mdb dump request");
+               return -EINVAL;
+       }
+       if (nlmsg_attrlen(nlh, sizeof(*bpm))) {
+               NL_SET_ERR_MSG(extack, "Invalid data after header in mdb dump request");
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
 static int br_mdb_dump(struct sk_buff *skb, struct netlink_callback *cb)
 {
        struct net_device *dev;
@@ -169,6 +192,13 @@ static int br_mdb_dump(struct sk_buff *skb, struct netlink_callback *cb)
        struct nlmsghdr *nlh = NULL;
        int idx = 0, s_idx;
 
+       if (cb->strict_check) {
+               int err = br_mdb_valid_dump_req(cb->nlh, cb->extack);
+
+               if (err < 0)
+                       return err;
+       }
+
        s_idx = cb->args[0];
 
        rcu_read_lock();