I _never_ suggested that "read" permission should permit crashing.
The issues are getting worked. As one example, /etc/usb/policy
could be used to chmod or chown the /proc/bus/usb device nodes,
so that user mode drivers can attach to those devices (even if
it still requires O_RDWR to read feature state, etc).
- Dave
----- Original Message -----
From: "Thomas Sailer" <[EMAIL PROTECTED]>
To: "David Brownell" <[EMAIL PROTECTED]>
Cc: "Adam J. Richter" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>;
<[EMAIL PROTECTED]>
Sent: Monday, 5 June, 2000 2:27 AM
Subject: Re: [linux-usb] Doh! I forgot to include the URL
> David Brownell wrote:
> >
> > > >2. Why open with O_RDWR? Is that a requirement of usbdevfs?
> >
> > Basically, yes -- even when performing "read" control messages.
> > Not a requirement I much like seeing imposed.
>
> IMNSHO one wants to give normal users the ability to see what
> devices are connected (they can read the stored descriptors), but
> one does not want an arbitrary user to crash an arbitrary USB device.
>
> Many USB devices can be crashed by sending an inappropriate control
> request even if it is only a read request. That's why write perms
> are required even for read requests. And btw. a read request
> also requires a write phase on the USB bus.
>
> Tom
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