[PATCH net-next 20/20] net/bridge: Update br_mdb_dump for strict data checking

[David Ahern]

From: David Ahern <dsah...@gmail.com>

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 <dsah...@gmail.com>
---
 net/bridge/br_mdb.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index a4a848bf827b..7beeee658d6c 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -162,6 +162,28 @@ static int br_mdb_fill_info(struct sk_buff *skb, struct 
netlink_callback *cb,
        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(extack, "Invalid header");
+               return -EINVAL;
+       }
+       if (bpm->ifindex) {
+               NL_SET_ERR_MSG(extack,
+                              "Filtering by device index is not supported");
+               return -EINVAL;
+       }
+       if (nlh->nlmsg_len != nlmsg_msg_size(sizeof(*bpm))) {
+               NL_SET_ERR_MSG(extack, "Invalid data after header");
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
 static int br_mdb_dump(struct sk_buff *skb, struct netlink_callback *cb)
 {
        struct net_device *dev;
@@ -169,6 +191,13 @@ 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)
+                       return err;
+       }
+
        s_idx = cb->args[0];
 
        rcu_read_lock();
-- 
2.11.0