Re: [PATCH v3 1/4] fs, net: Standardize on file_receive helper to move fds across processes

On Wed, Jun 10, 2020 at 08:48:45AM +0000, David Laight wrote:

From: Sargun Dhillon

...

Sent: 10 June 2020 09:13

In essence the 'copy_to_user' is done by the wrapper code. The code filling in the CMSG buffer can be considered to be writing a kernel buffer.

IIRC other kernels (eg NetBSD) do the copies for ioctl() requests in the ioctl syscall wrapper. The IOW/IOR/IOWR flags have to be right.

Yeah, this seems like it'd make a lot more sense (and would have easily caught the IOR/IOW issue pointed out later in the thread). I wonder how insane it would be to try to fix that globally in the kernel...