Re: localdev and fixed devices

A compromise approach could be to introduce boolean alias variables for
common deny criteria, such as:

LOCALDEV_DENY_HARDDISK = True (denies IDE and SCSI hard drives)
LOCALDEV_DENY_USB = True  (denies all USB devices)

and these variables would simply set LOCALDEV_DENY to the proper value,
while still allowing the admin the flexibility of setting LOCALDEV_DENY
themselves using the syntax to get the full control.

-Gideon

On Sun, 2008-09-07 at 08:30 -0400, Gideon Romm wrote:
> Cyberorg-
> 
> While, in general, I also like to keep geeky stuff behind the scenes,
> this is one time where you cripple the flexibility of this variable A
> LOT by doing so.
> 
> For example, if we used the vars as you suggest, we could only block ALL
> scsi devices, and not *just* the hard scsi hard drives (leaving scsi
> CDROM drives accessible).
> 
> Plus, there are lots of additional udevinfo parameters that can be used
> to match against for different situations - ones we may not be able to
> anticipate.
> 
> For example, I want to make sure nothing made by SANDISK is ever
> mounted.  Or no "video" devices.  Or no .....
> 
> This simple syntax will allow a great deal of custom tailoring to the
> admin.  And there are already easy tools for the admin to discover both
> the variables and their values.
> 
> Simplifying it further in lts.conf will surely weaken things IMHO.
> 
> -Gadi
> 
> On Sun, 2008-09-07 at 11:41 +0530, CyberOrg wrote:
> > On Sun, Sep 7, 2008 at 10:39 AM, Gideon Romm
> > <[email protected]> wrote:
> > > Hi, everybody.
> > >
> > > Please check out this branch for a proposed solution:
> > >
> > > lp:~gideon/ltsp/ltspfs-trunk-gadi
> > >
> > > I introduce an lts.conf parameter called "LOCALDEV_DENY".  With this
> > > parameter, you can deny local devices based upon udevinfo criteria or
> > > combinations of several udevinfo criteria.
> > >
> > Thats a great idea :)
> > 
> > > Syntax:
> > >
> > > LOCALDEV_DENY = "var1:val1,var2:val2,var3:val3+var4:val4"
> > >
> > > Which means:
> > >
> > > Deny local devices if:  var1 = val1 OR var2 = val2 OR (var3 = val3 AND
> > > var4 = val4)
> > >
> > > So, if I want to block all local scsi hard drives, I simply do:
> > >
> > > LOCALDEV_DENY = "ID_TYPE:disk+ID_BUS:scsi"
> > >
> > > To block all USB devices:
> > >
> > > LOCALDEV_DENY = "ID_BUS:usb"
> > >
> > > To block all IDE and SCSI hard drives:
> > >
> > > LOCALDEV_DENY = "ID_TYPE:disk+ID_BUS:scsi,ID_TYPE:disk+ID_BUS:ide"
> > >
> > 
> > Can't this be done by the script reading the variable?
> > 
> > We can predefine some of the common local devices, so  user just enters:
> > 
> > LOCALDEV_DENY_0=IDE
> > LOCALDEV_DENY_1=SCSI
> > LOCALDEV_DENY_2=USB
> > 
> > To block all IDE, SCSI and USB, allowing multiple use of LOCALDEV_DENY
> > variable. All the geeky udev stuff can be handled behind the scenes.
> > 
> > Cheers
> > 
> > -J
> > 
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-- 
Gideon Romm <[email protected]>


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