Default permissions

On Thu, Oct 20, 2005 at 09:40:45PM +0200, John Nilsson wrote:
> On Thu, 2005-10-20 at 13:51 -0400, John Richard Moser wrote:
> > As requested on bug #17424, this discussion is being brought to this list.
> > 
> > I feel it needs to be determined whether or not the default umasks and
> > /home or /root directories need to be 0700 or not.  I have come up with
> > several reasons why the current setting of 0755 is a problem.
> 
> Is there _any_ reason for having o+r?

The ability for users to share files with each other easily. With the
exception of big commercial shell account providers, it is generally
sensible to assume that multiple users on the same box have some
connection to one another (on home systems, they'll generally be family
members; on hobbyist colo systems, they'll be friends; on corporate
systems, they'll be colleagues), and it's often convenient for them to
be able to share files with one another without being able to jump
through hoops. I'd rather not encourage the use of mail for large files.

I don't buy "information leakage" as a trump card when the alternative
is making it difficult for (say) me to tell my wife "I haven't had time
to put those photos up on the web yet, but they're somewhere in my home
directory if you want to have a look", or for me to debug co-workers'
.bashrc files when they're having difficulty committing to arch
archives, or any of a number of other things people do frequently.

This question comes up frequently.

> /home/* should default to 07[0157]1, IMHO 0701 would be sensible.

No, if you need that, you're likely running a system with many unrelated
shell accounts provided to people you don't know, and it should be
simple to preseed adduser/homedir-permission to false in the installer
or to tweak /etc/adduser.conf later.

(Even so, it's a bit silly for group permissions to be less than world
permissions ...)

Cheers,

-- 
Colin Watson                                       [cjwatson at ubuntu.com]