Re: [RFC, PATCH] sys_revoke(), just a try. (was: Re: dynamic /dev security hole?)

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

On Iau, 2004-08-12 at 17:49, Michael Buesch wrote:
> +static ssize_t revoke_read(struct file *filp,
> +			   char *buf,
> +			   size_t count,
> +			   loff_t *ppos)
> +{
> +	return 0;
> +}

-EIO I think but I'm not sure I remember the BSD behaviour in full

> +static int filp_revoke(struct file *filp, struct inode *inode)
> +{

First problem here is that the handle might still be in use
for mmap, so you'd need to undo mmaps on it. A second is that 
while you can ->flush() here you can't really close it until the
file usage count hits zero. 

You are btw tackling a really really hard problem and its more likely
the way to do this is to add revoke() methods to drivers and do it at
the driver level - as the tty layer does with vhangup.