Brad:

Given my user and security situation, number 2 seems reasonable, except
that the man page for mount on my system does not show a devmode
option.  I did find the place where the usb system gets mounted in
rc.sysinit, as follows:

action $"Mounting USB filesystem: "  mount -t usbdevfs usbdevfs
/proc/bus/usb

And it shows up in mtab as follows:

usbdevfs /proc/bus/usb usbdevfs rw 0 0

So, the question is, can I just edit the mount command in rc.sysinit
directly and add the appropriate mount options?  Thanks for the info.

Neil

On Sat, 2002-02-16 at 20:54, Brad Hards wrote:
> > 3. I'm not quite sure what you you mean by the "device node".
> The device node is the interface between user space and kernel space. For 
> example, the mouse is:
> crw-------    1 root     root      13,  63 Aug 31 06:30 /dev/input/mice
> and the permissions on the /proc/bus/usb/001/002 node are:
> -rw-r--r--    1 root     root           18 Feb 15 13:18 /proc/bus/usb/001/002
> 
> This is a sensible default.
> 
> However it does mean that you need to be root to write anything to the device 
> (which is a lot of USB transactions, because of the way USB works).
> 
> Some suggestions:
> 1. Change the rights on the particular node (whichever /proc/bus/usb/X/Y entry 
> corresponds) to +w. See the manual entry for chmod. You can probably do this 
> automagically with an entry in /sbin/hotplug. THIS IS INSECURE UNLESS YOU ARE 
> THE ONLY PERSON WITH ACCESS TO THE SYSTEM.
> 2. Change the mount options for usbdevfs, using the devmode option:
> mount /proc/bus/usb -o remount,devmode=0666
> (see the manual entry for mount for more information). THIS IS EVEN MORE 
> INSECURE THAN THE FIRST OPTION.
> 3. Run the nomad utility suid root. THIS IS VERY DANGEROUS IF THERE IS A BUG 
> IN THE NOMAD UTILITY. (man chmod, s option)
> 4. Modify pam configuration (read the manual entry and probably the system 
> admin's guide) to configure the particular device node to belong to you when 
> you log in, if the device is connected. IF YOU MISCONFIGURE PAM, YOU MAY NOT 
> BE ABLE TO LOG IN.
> 
> I'd probably do 2, because I control my laptop, and it is easy. Your situation 
> may vary, and you need to assess the risks.
> 
> Brad
> 



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