Re: [PATCH 1/1] Char: moxa, prevent opening unavailable ports

[Jiri Slaby]

On 06/09/2009 09:27 PM, Andrew Morton wrote:
> btw, what's this code in moxa_open() doing?
> 
> 	if (port == MAX_PORTS) {
> 		return capable(CAP_SYS_ADMIN) ? 0 : -EPERM;
> 	}
> 
> why does it return 0 if CAP_SYS_ADMIN?				

There is some global stats ioctl crap on that port number available only
to users with permissions. Look at moxa_ioctl, there is:

        if (tty->index == MAX_PORTS) {
                if (cmd != MOXA_GETDATACOUNT && cmd != MOXA_GET_IOQUEUE &&
                                cmd != MOXA_GETMSTATUS)
                        return -EINVAL;

Of course, there is also alloc_tty_driver(MAX_PORTS + 1).
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