Re: [PATCH v6 1/7] mseal, system mappings: kernel config and header change

[Kees Cook <kees@kernel.org>]

On Mon, Feb 24, 2025 at 02:10:58PM -0500, Liam R. Howlett wrote:
> * Kees Cook <kees@kernel.org> [250224 13:55]:
> > On Mon, Feb 24, 2025 at 10:52:13AM -0800, Dave Hansen wrote:
> > > On 2/24/25 10:44, Jeff Xu wrote:
> > > > For example:
> > > > Consider the case below in src/third_party/kernel/v6.6/fs/proc/task_mmu.c,
> > > > 
> > > > #ifdef CONFIG_64BIT
> > > > [ilog2(VM_SEALED)] = "sl",
> > > > #endif
> > > > 
> > > > Redefining VM_SEALED  to VM_NONE for 32 bit won't detect the problem
> > > > in case that  "#ifdef CONFIG_64BIT" line is missing.
> > > > 
> > > > Please note, this has been like this since the first version of
> > > > mseal() RFC patch, and I prefer to keep it this way.
> > > 
> > > That logic is reasonable. But it's different from the _vast_ majority of
> > > other flags.
> > > 
> > > So what justifies VM_SEALED being so different? It's leading to pretty
> > > objectively ugly code in this series.
> > 
> > Note that VM_SEALED is the "is this VMA sealed?" bit itself. The define
> > for "should we perform system mapping sealing?" is intentionally separate
> > here, so that it can be Kconfig and per-arch toggled, etc.
> > 
> 
> Considering Dave is the second person that did not find the huge commit
> message helpful, can we please limit the commit message to be about the
> actual code and not the entire series?
> 
> I thought we said that it was worth while making this change in v5?

Right, please minimize patch #1's commit log to just what it is doing,
etc, and leave the rest of the rationale in the 0/N cover letter.

-- 
Kees Cook