Wednesday, September 16, 2020

xsane under 6.7

The docs kept saying make sure your device has the necessary permissions,
without saying exactly in which sense that was meant.

Finally, a few weeks ago I got most of my machines upgraded properly to
6.7, they were mostly 6.4 or earlier.

Went to try my Canon flatbed scanner and xsane would only work under root.
Puzzled about that for a bit, did some googling and reading about
belonging to groups like operator and _saned, but my main account still
belonged to those groups so what else had changed. Root could see the
device but I couldn't, even though I had my main account in wheel group.

I looked at all the sub-devices the scanner could connect to and player
with adding group privilege to then since they were in group wheel

Never did quite understand all the implications of the USB structure,
since been using OpenBSD so long that the earliest machines I put it on,
didn't even have USB devices...

But what had changed in the latest versions?

I looked at usb1 which corresponds to one of the master usb controller
levels. It had user root rw and wheel group r bits, and am thinking
that a scanner is only a read device, right? Good enough, right?

Nope! Dope! You have to be able to send commands to it as well to tell
it when and how to scan.

As root:

chmod g+w /dev/usb1

and lo and behold my main account could use the scanner again.

I don't know if the subdevices needed the group permission changes
too, but I had done that already. They didn't have privileges for wheel
originally before I set them up in mass. Maybe I better revisit the
question of what privileges subdevices should have in light of
current security issues, if any.

I guess, at some point in recent releases the makedev step stopped
automatically allowing "write" for wheel on the usb1 device, for some good
reason.

Figured I put a success story up instead of a complaint, for a change,
leaving a trail of enough key words that some one else might be able to
google for it.

Austin

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