linux-kernel - Re: [PATCH 1/3] mm: security: Move hardened usercopy under 'Kernel hardening options'

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Message-ID: <aapczkb5toqvhe7cdtiyh5yl3etuptr3t6ceuhx2gp44byr5me@z3oar4quneda>
Date: Tue, 21 Jan 2025 09:21:55 +0000
From: Mel Gorman <mgorman@...hsingularity.net>
To: Kees Cook <kees@...nel.org>
Cc: Daniel Micay <danielmicay@...il.com>, linux-hardening@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] mm: security: Move hardened usercopy under 'Kernel
 hardening options'

On Mon, Jan 20, 2025 at 01:10:44PM -0800, Kees Cook wrote:
> On Fri, Jan 17, 2025 at 01:03:35PM +0000, Mel Gorman wrote:
> > There is a submenu for 'Kernel hardening options' under "Security".
> > Move HARDENED_USERCOPY under the hardening options as it is clearly
> > related.
> > 
> > Signed-off-by: Mel Gorman <mgorman@...hsingularity.net>
> > ---
> >  security/Kconfig           | 12 ------------
> >  security/Kconfig.hardening | 16 ++++++++++++++++
> >  2 files changed, 16 insertions(+), 12 deletions(-)
> > 
> > diff --git a/security/Kconfig b/security/Kconfig
> > index 28e685f53bd1..fe7346dc4bc3 100644
> > --- a/security/Kconfig
> > +++ b/security/Kconfig
> > @@ -159,18 +159,6 @@ config LSM_MMAP_MIN_ADDR
> >  	  this low address space will need the permission specific to the
> >  	  systems running LSM.
> >  
> > -config HARDENED_USERCOPY
> > -	bool "Harden memory copies between kernel and userspace"
> > -	imply STRICT_DEVMEM
> > -	help
> > -	  This option checks for obviously wrong memory regions when
> > -	  copying memory to/from the kernel (via copy_to_user() and
> > -	  copy_from_user() functions) by rejecting memory ranges that
> > -	  are larger than the specified heap object, span multiple
> > -	  separately allocated pages, are not on the process stack,
> > -	  or are part of the kernel text. This prevents entire classes
> > -	  of heap overflow exploits and similar kernel memory exposures.
> > -
> >  config FORTIFY_SOURCE
> >  	bool "Harden common str/mem functions against buffer overflows"
> >  	depends on ARCH_HAS_FORTIFY_SOURCE
> > diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening
> > index c9d5ca3d8d08..00e6e2ed0c43 100644
> > --- a/security/Kconfig.hardening
> > +++ b/security/Kconfig.hardening
> > @@ -279,6 +279,22 @@ config ZERO_CALL_USED_REGS
> >  
> >  endmenu
> >  
> > +menu "String manipulation"
> 
> I think "string" means different things to different people. I'd prefer
> "Bounds checking" or "Spatial safety" if it's going to be a separate
> menu section.
> 

I will change it to "Bounds checking" in v2.

Thanks.

-- 
Mel Gorman
SUSE Labs