Subject: Re: [RFC] git-format-patch: default to --from to avoid spoofed mails?

From: Josh Triplett <[email-masked]>
Date: Thu, 28 Jul 2016 17:05:07 -0700

On Thu, Jul 28, 2016 at 02:37:04PM -0700, Junio C Hamano wrote:
> Josh Triplett <[email-masked]> writes:
> 
> > I'd like to propose changing the default behavior of git-format-patch to
> > --from (and adding a --from-author option to override, and perhaps a
> > config setting).  This will not change the output *except* when
> > formatting patches authored by someone else.  git-am and git-send-email
> > both handle the --from format without any issues.
> 
> I see this in "format-patch --help":
> 
>            Note that this option is only useful if you are actually
>            sending the emails and want to identify yourself as the
>            sender, but retain the original author (and git am will
>            correctly pick up the in-body header).  Note also that
>            git send-email already handles this transformation for
>            you, and this option should not be used if you are
>            feeding the result to git send-email.
> 
> The first one says "only useful", but it seems what it really means
> is "it becomes no-op if you are sending your own patch anyway".  So
> that one does not worry me.  What is most worrysome is the latter
> half of the last sentence.  Is it really "should not be", or is it
> merely "use of this option is just a waste of time, as you would get
> exactly the same result anyway"?  If it is the latter, that is fine.

As far as I can tell, it's the latter.  git send-email can do this same
transformation, but handles mails that already have the transformation
done to them without any issue.

> One thing I absolutely do not want to see is people to start
> repeating their own ident on in-body "From: " header when they send
> their own patch.  That would waste everybody's time pointing out
> "You do not have to do that, it merely adds noise".  As long as you
> can guarantee that your change won't increase the rate of that, I am
> fine with the proposal.

git format-patch with --from *only* adds an in-body "From:" if the
commit author differs from the local committer identity.  So, as far as
I can tell, the only scenario that would produce additional in-body "From:"
headers here would be if someone had failed to configure their git
identity, and manually set the author for their own commits.  (In which
case, they'd also have a broken "From:" in any cover letter they
generated.)

So, it seems exceedingly unlikely to me that this would result in
unnecessary in-body "From:" headers.

- Josh Triplett