[cgl_discussion] Re: Buffer overflow

Makan Pourzandi (LMC) Makan.Pourzandi at ericsson.ca
Mon Apr 28 12:06:26 PDT 2003

Hi all, 

There are already several valid open source projects regarding buffer overflow, also given the necessity of protecting the system against the numerous buffer overflows. I propose considering the requirement for CGL 2.0, it means as for section 6 (For example, Pax mechanisms are already part of trusted debian, openbsd (ok, not linux, I know :-)), and several others .... ).   

New proposition: 

6.2.2	Support for buffer overflows protection mechanisms

One of the major sources of vulnerability on Linux is buffer overflows. For time being, several projects exist that implement the protection against these buffer overflows through the OS: non-executable stack, randomizing the place a program is loaded into memory... These mechanisms must be supported in order to protect the system against buffer overflows.

Threats mitigated: 
These mechanisms mitigate the possible buffer overflows. This mitigates the theft of root privileges and unauthorized access. 

Security level: 		3

Priority: 			1

Maturity:			Usable 

Category: 			Configurable 

1.	PaX kernel Patch: "The goal of the PaX project is to research various defense mechanisms against the exploitation of software bugs that give an attacker arbitrary read/write access to the attacked task's address space. This class of bugs contains among others various forms of buffer overflow bugs (be they stack or heap based), user supplied format string bugs, etc."  (http://pageexec.virtualave.net/ )
2.	StackGuard is an enhancement to GCC that generates programs robust against stack-smashing attacks.  http://www.immunix.org/stackguard.html  
3.	ProPolice is an enhancement to GCC that generates programs robust against stack-smashing attacks.  http://www.trl.ibm.com/projects/security/ssp/ 

> -----Original Message-----
> From: Mika Kukkonen [mailto:mika at osdl.org]
> Sent: Thursday, April 24, 2003 12:25 PM
> To: Greg KH
> Cc: cgl_discussion at lists.osdl.org; Makan Pourzandi (LMC); Campadello
> Stefano
> Subject: Re: [cgl_discussion] Re: Buffer overflow
> On Thu, 2003-04-24 at 08:57, Greg KH wrote:
> > On Thu, Apr 24, 2003 at 08:22:05AM -0700, Mika Kukkonen wrote:
> > > On Wed, 2003-04-23 at 17:23, Greg KH wrote:
> > > (...)
> > > > And there's things like the StackGuard or ProPolice gcc 
> patches that
> > > > might be better to point people at.  However, that's 
> not a kernel
> > > > patch/feature, so would not fall under the CGL spec :)
> (...)
> > Ok then, why not specify a specific version of gcc (like the above
> > mentioned versions) if you all really want to worry about 
> something like
> > this?
> AFAIK some distros already ship with their own modified 
> version of gcc same
> way as they ship with their own modified version of Linux 
> kernel, and from
> CGL viewpoint this is OK (we do aim to get 99% of our 
> features into mainline
> kernel/gcc, but sometimes that takes a loooong time, or never 
> because of
> non-technical issues).
> So if our security people feel like adding a generic requirement like
> "CGL C-complier should provide the option to compile applications with
> StackGuard/ProPolice", I do not have an issue with it.
> But I do think this kind of additional checking (which always 
> comes with
> price tag on performance) should be optional, with the actual 
> decision of
> whether to use it or not left to the distros and their 
> customers. Hence
> the word "optional" in my example above.
> Makan/Stefano, any thoughts?
> --MiKu

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