[Novalug] USB as non-root

James Ewing Cottrell 3rd JECottrell3@Comcast.NET
Sun Dec 6 18:44:42 EST 2009


Jon LaBadie wrote:
> On Thu, Nov 26, 2009 at 12:21:55PM +0100, Miguel Gonzlez Castaos wrote:
>   
>> Bryan J Smith wrote:
>>     
>>> If you formatted the device as Ext3 then it will have root by default,
>>> of course. Change the permissions with chmod to 1777 so anyone
>>> can read/write their own files.
>>>   
>>>       
>> Just wondering (I'm not a security guy), is it safe to chmod 1777 when 
>> the partition is mounted as root?
> For user mounted filesystems, and particularly, for udev automagically
> mounted usb sticks etc, is the "nosuid" option invoked by default?
> Otherwise there could be a security issue with setuid progs existing
> on the newly mounted media.
Good Question. I dunno, but it shouldn't be hard to figure it out. 
Simply type 'mount' and look at the options. Given that a daemon 
(probably running as root) is doing it, anything is possible.

However, I would bet (but only a small amount of money) that "nosuid" 
(and "nodev", which is just as important) is set, because it tends to go 
with "auto".

JIM



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