Re: [PATCH iwl-next v3 1/6] ip_tunnel: use a separate struct to store tunnel params in the kernel

From: Andy Shevchenko <andy@kernel.org>
Date: Fri, 21 Jul 2023 17:21:51 +0300

On Fri, Jul 21, 2023 at 09:15:27AM +0200, Marcin Szycik wrote:

quoted

From: Alexander Lobakin <aleksander.lobakin@intel.com>

Unlike IPv6 tunnels which use purely-kernel __ip6_tnl_parm structure
to store params inside the kernel, IPv4 tunnel code uses the same
ip_tunnel_parm which is being used to talk with the userspace.
This makes it difficult to alter or add any fields or use a
different format for whatever data.
Define struct ip_tunnel_parm_kern, a 1:1 copy of ip_tunnel_parm for
now, and use it throughout the code. The two places where the latter
is used to interact with the userspace, now do a conversion from one
type to another, with manual field-by-field assignments.
Must be done at once, since ip_tunnel::parms is being used in most
of those places.

...

quoted

+	strscpy(kp.name, p.name, sizeof(kp.name));
+	kp.link = p.link;
+	kp.i_flags = p.i_flags;
+	kp.o_flags = p.o_flags;
+	kp.i_key = p.i_key;
+	kp.o_key = p.o_key;
+	memcpy(&kp.iph, &p.iph, min(sizeof(kp.iph), sizeof(p.iph)));
+
+	err = dev->netdev_ops->ndo_tunnel_ctl(dev, &kp, cmd);
+	if (err)
+		return err;
+
+	strscpy(p.name, kp.name, sizeof(p.name));
+	p.link = kp.link;
+	p.i_flags = kp.i_flags;
+	p.o_flags = kp.o_flags;
+	p.i_key = kp.i_key;
+	p.o_key = kp.o_key;
+	memcpy(&p.iph, &kp.iph, min(sizeof(p.iph), sizeof(kp.iph)));

quoted

+		strscpy(kp.name, p.name, sizeof(kp.name));
+		kp.link = p.link;
+		kp.i_flags = p.i_flags;
+		kp.o_flags = p.o_flags;
+		kp.i_key = p.i_key;
+		kp.o_key = p.o_key;
+		memcpy(&kp.iph, &p.iph, min(sizeof(p.iph), sizeof(kp.iph)));

Seems to me these two deserves separate helpers to avoid such a duplication(s).

Sounds reasonable, thanks!

Olek