[patch] allow write() on SOCK_PACKET sockets

[Stas Sergeev]

Hello.

Unless I am really missing something, there
seem to be no reason why the SOCK_PACKET code
does not allow to use write() or send() when
the socket was bound, and insists on using
sendto(). SOCK_RAW code, in comparison, allows
write() after bind().
Attached patch allows write() for the SOCK_PACKET
sockets when they are bound.
Can this be applied, or am I missing the point?

Signed-off-by: Stas Sergeev <stsp@xxxxxxxx>

--- linux/net/packet/af_packet.c	2004-06-26 15:20:54.000000000 +0400
+++ linux/net/packet/af_packet.c	2004-10-10 02:25:41.000000000 +0400
@@ -322,16 +322,23 @@
 			return(-EINVAL);
 		if (msg->msg_namelen==sizeof(struct sockaddr_pkt))
 			proto=saddr->spkt_protocol;
+		/*
+		 *	Find the device first to size check it 
+		 */
+
+		saddr->spkt_device[13] = 0;
+		dev = dev_get_by_name(saddr->spkt_device);
 	}
 	else
-		return(-ENOTCONN);	/* SOCK_PACKET must be sent giving an address */
-
-	/*
-	 *	Find the device first to size check it 
-	 */
+	{
+		struct packet_opt *po = pkt_sk(sk);
+		if (!po->running || !po->prot_hook.dev)
+			return -ENOTCONN;	/* SOCK_PACKET must be sent giving an address */
+		proto = po->prot_hook.type;
+		dev = po->prot_hook.dev;
+		dev_hold(dev);
+	}
 
-	saddr->spkt_device[13] = 0;
-	dev = dev_get_by_name(saddr->spkt_device);
 	err = -ENODEV;
 	if (dev == NULL)
 		goto out_unlock;