Re: GACI item list - to give some items for discussion

pollardat_private

dawat_private (David Wagner):
> richard offer wrote:
> >Because I'm trying to write a well behaved application that doesn't generate
> >more errors than it needs too ?
> 
> What do you mean?  The canonical code is something like
>   if ((fd = open(path, O_RDONLY)) < 0) {
>     return NULL; /* open failed */
>   }
>   /* use fd */
> This is the usual Unix way.  You seem to be arguing that apps need to
> be able to write code like this:
>   if (allowed_to_open(path, O_RDONLY) < 0) {
>     return NULL; /* open failed */
>   }
>   fd = open(path, O_RDONLY);
>   /* use fd */
> I'd argue that the latter is, if anything, *worse* than the former.
> It's more error-prone: What if the open() really fails?  It's also
> more dangerous: What about race conditions and TOCTTOU attacks?
> 
> >I want to give the adminster of the machine useful failure information, not cry
> >wolf on every event ?
> 
> Then the problem is with your intrusion detection system, not with
> the interface to the open() call...
> 
> My argument is: We should try for flexibility.  We should of
> course allow a module to support this functionality if it wants,
> but the question is: Do we require all modules to allow apps to
> make allowed_to_open() type of queries?  I don't see any reason
> to place this restriction on modules.
> 
> If your modules can support allowed_to_open(), and my modules
> can deliberately skip implementing it, can we both go home happy?
> Or are you suggesting that supporting allowed_to_open() should be
> mandatory for all modules?

That wasn't quite the question I was considerding:

	a) Would I be allowed to open the file IF I had the following...

The question posed by the samble code above is:

	b) Would I be allowed to open the file IF I attempted to open
	   the file..

Big difference. The question a) is more like what would be used by daemons
(NFS/Samba...) to avoid changing uid. The second question b) is not really
usefull since the open itself makes the same query.

-------------------------------------------------------------------------
Jesse I Pollard, II
Email: pollardat_private

Any opinions expressed are solely my own.

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