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Date:      Sat, 10 May 2014 15:29:53 -0600
From:      Warner Losh <imp@bsdimp.com>
To:        Shawn Webb <lattera@gmail.com>
Cc:        freebsd-current@freebsd.org
Subject:   Re: Recent Changes to WITH_*/WITHOUT_* in src
Message-ID:  <F5E246EB-BCB7-48A4-9540-935D8D9B1F05@bsdimp.com>
In-Reply-To: <20140510212531.GT3063@pwnie.vrt.sourcefire.com>
References:  <20140510164512.GS3063@pwnie.vrt.sourcefire.com> <73589111-84D9-40EA-89F1-330396E853DA@bsdimp.com> <20140510212531.GT3063@pwnie.vrt.sourcefire.com>

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On May 10, 2014, at 3:25 PM, Shawn Webb <lattera@gmail.com> wrote:

> On May 10, 2014 02:14 PM -0600, Warner Losh wrote:
>>=20
>> On May 10, 2014, at 10:45 AM, Shawn Webb <lattera@gmail.com> wrote:
>>=20
>>> Hey All,
>>>=20
>>> It seems that the recent changes to the makefiles for building
>>> world/kernel have broken some modifications I have locally for
>>> implementing ASLR+PIE. I'm quite the bsd make newbie, so I thought =
I'd
>>> ask for a bit of help. I'm sure the solution is quite simple.
>>>=20
>>> My code is up on GitHub. I'll include links at the bottom of the =
email.
>>>=20
>>> The code in question is in share/mk/bsd.prog.mk, where I'm checking =
to
>>> see if MK_PIE is not equal to "no". Prior to the recent changes, =
this
>>> code used to work. (Please note that I know that the way I'm cheking =
is
>>> a bit bloated, if anyone has any suggestions to trim my code down, =
let
>>> me know).
>>=20
>> You?ll need to add PIE to DEFAULT_NO_OPTIONS in bsd.opts.mk since
>> bsd.*.mk files need it.
>>=20
>=20
> Thanks a lot! Adding it to that one worked.
>=20
> But what's the difference between the DEFAULT_NO_OPTIONS in =
src.opts.mk and
> bsd.opts.mk?

Options to build FreeBSD=92s /usr/src are defined in src.opts.mk. =
Options tested by bsd.*.mk, which can be used to build other things, are =
in bsd.opts.mk.=20

>>> How this feature is supposed to work is:
>>> 1) PIE is added to the __DEFAULT_NO_OPTIONS to make building
>>> applications as position-independent executables opt-in.
>>> 2) User adds WITH_PIE=3D1 to /etc/src.conf or /etc/make.conf
>>> 3) The application being built needs to also specify CAN_PIE=3D1 in =
its
>>> Makefile. This is because some applications don't support being =
built as
>>> a position-independent executable.
>>> 4) If MK_PIE is not "no" and CAN_PIE is defined, then add additional
>>> CFLAGS.
>>>=20
>>> The log from my build is here: http://ix.io/cf0
>>>=20
>>> My code is here:
>>> =
https://github.com/HardenedBSD/hardenedBSD/blob/hardened/current/aslr/shar=
e/mk/bsd.prog.mk#L14-L22
>>=20
>> Maybe RESCUE should define NO_SHARED=3Dyes since it is building a
>> static binary so you can eliminate a special case that infects the =
bsd.*.mk files
>> with defines from our src build?
>>=20
>=20
> That sounds like a good idea. Since that's outside the scope of my =
ASLR
> work, should I file a PR for that?

Nah, mostly a poke at a 20 year old mistake :)

>> Hate that you are propagating the NO_SHARED=3Dno interface, but can?t
>> offer at better suggestion at the moment. I?d kinda like to kill =
that?
>=20
> In looking at the Makefiles, it seems like NO_*/YES_* is being phased
> out. Once a suitable alternative to NO_SHARED is in place, I'll make
> adjustments on my end.

Yea, NO_SHARED likely is going to be the last to die :) NO_FOO used to =
be both a Makefile command and a user option. I=92m eliminating the =
latter, although some of the former may live on.

Warner


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