Re: [PATCH v2 net-next 21/23] net/bridge: Update br_mdb_dump for strict data checking

[Christian Brauner <christian@brauner.io>]

On Sun, Oct 07, 2018 at 08:16:42PM -0700, David Ahern wrote:
> From: David Ahern <dsahern@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 <dsahern@gmail.com>

Acked-by: Christian Brauner <christian@brauner.io>

> ---
>  net/bridge/br_mdb.c | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
> 
> diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
> index a4a848bf827b..a7ea2d431714 100644
> --- a/net/bridge/br_mdb.c
> +++ b/net/bridge/br_mdb.c
> @@ -162,6 +162,29 @@ 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_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();
> -- 
> 2.11.0
>