Re: [PATCH net-next 0/3] strp: Generalize stream parser to work with other socket types

On Sun, Aug 28, 2016 at 8:34 PM, David Miller [off-list ref] wrote:

From: Tom Herbert <redacted>
Date: Sun, 28 Aug 2016 14:43:16 -0700

quoted

Add a read_sock protocol operation function that allows something like
tcp_read_sock to be called for other protocol types.

Specific changes in this patch set:
  - Add read_sock function to proto_ops. This has the same signature as
    tcp_read_sock. sk_read_actor_t is also defined in net.h.
  - Set peek_len and read_sock proto_op functions for TCPv4 and TCPv6
    stream ops.
  - Remove references to tcp in strparser.
  - Call peek_len and read_sock operations from strparser instead of
    calling TCP specific functions.

I'll apply this, but I want you to shore up these new ops.

A check has to happen somewhere to make sure the proto_ops in
question have a non-NULL read_sock and peek_len method before
starting to use it.

Is the check in strp_init not enough?...

@@ -424,9 +429,14 @@ static void strp_rx_msg_timeout(unsigned long arg)
 int strp_init(struct strparser *strp, struct sock *csk,
              struct strp_callbacks *cb)
 {
+       struct socket *sock = csk->sk_socket;
+
        if (!cb || !cb->rcv_msg || !cb->parse_msg)
                return -EINVAL;

+       if (!sock->ops->read_sock || !sock->ops->peek_len)
+               return -EAFNOSUPPORT;
+