Date: Fri, 17 Oct 2014 07:41:22 -0600 From: Warner Losh <imp@bsdimp.com> To: Shawn Webb <lattera@gmail.com> Cc: hunger@hunger.hu, David Carlier <david.carlier@hardenedbsd.org>, Oliver Pinter <oliver.pntr@gmail.com>, PaX Team <pageexec@freemail.hu>, Sean Bruno <sbruno@freebsd.org>, Konstantin Belousov <kib@freebsd.org>, FreeBSD Arch <freebsd-arch@freebsd.org>, Jeremie Le Hen <jlh@freebsd.org>, Bryan Drewery <bdrewery@freebsd.org> Subject: Re: PIE/PIC support on base Message-ID: <315B4DC5-0E04-4F6B-BBB0-477D049025BF@bsdimp.com> In-Reply-To: <CADt0fhweiymn2D09%2Be7f44AreWe%2B8cmAtDVeec0NfmuWuOOhbg@mail.gmail.com> References: <CAMe1fxaYn%2BJaKzGXx%2Bywv8F0mKDo72g=W23KUWOKZzpm8wX4Tg@mail.gmail.com> <CAGSa5y3s9r0DRyinfqV=PJc_BT=Em-SLfwhD25nP0=6ki9pHWw@mail.gmail.com> <CAMe1fxaBEc5T77xjpRsMi_kkc5LXwPGooLWTO9C1FJcLSPnO8w@mail.gmail.com> <CAGSa5y2=bKpaeLO_S5W%2B1YGq02WMgCZn_5bbEMw%2Bx3j-MYDOoA@mail.gmail.com> <CADt0fhzg5G1cLEBNfHXSEi9iP7mCP=8sSwpXbFobig=pm=QsFQ@mail.gmail.com> <CAGSa5y1LBxkUNSgKkw=F9_uykXDeBV7_WL0a7Wt%2B%2BGgMTSULEQ@mail.gmail.com> <CADt0fhweiymn2D09%2Be7f44AreWe%2B8cmAtDVeec0NfmuWuOOhbg@mail.gmail.com>
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--Apple-Mail=_C9A81F84-205F-4468-B0E6-6F6B44558AF7 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 On Oct 17, 2014, at 2:05 AM, Shawn Webb <lattera@gmail.com> wrote: > On Fri, Oct 17, 2014 at 3:53 AM, Jeremie Le Hen <jlh@freebsd.org> = wrote: >=20 >> On Fri, Oct 17, 2014 at 12:15 AM, Shawn Webb <lattera@gmail.com> = wrote: >>>=20 >>>=20 >>> On Thu, Oct 16, 2014 at 5:59 PM, Jeremie Le Hen <jlh@freebsd.org> = wrote: >>>>=20 >>>> On Thu, Oct 16, 2014 at 8:21 PM, David Carlier >>>> <david.carlier@hardenedbsd.org> wrote: >>>>>=20 >>>>> I chose the "atomic" approach, at the moment very few binaries are >>>>> concerned at the moment. So I applied INCLUDE_PIC_ARCHIVE in the >> needed >>>>> libraries plus created WITH_PIE which add fPIE/fpie -pie flags = only if >>>>> you >>>>> include <bsd.prog.pie.mk> (which include <bsd.prog.mk>...) = otherwise >>>>> other >>>>> binaries include <bsd.prog.mk> as usual hence does not apply. Look >>>>> reasonable approach ? >>>>=20 >>>> I think I understand what you mean. But I think PIE is commonplace >>>> nowadays and I don't understand what you win by not enabling it for >>>> the whole system. Is it a performance concern? Is it to preserve >>>> conservative minds from to much change? :) >>>=20 >>>=20 >>> Looping in Kostik, Bryan Drewery, the PaX team, Hunger, and Sean = Bruno. >>>=20 >>> On i386, there is a performance cost due to not having an extra = register >>> available for the relocation work that has to happen. PIE doesn't = carry >> much >>> of a performance penalty on amd64, though it still does carry some = on >> first >>> resolution of functions (due to the extra relocation step the RTLD = has to >>> worry about). On amd64, after symbol resolution has taken place, = there >> is no >>> further performance penalty due to amd64 having an extra register to = use >> for >>> PIE/PIC. I'm unsure what, if any, performance penalty PIE carries on = ARM, >>> AArch64, and sparc64. >>>=20 >>> Certain folk would prefer to see PIE enabled only in certain >> applications. >>> /bin/ls can't really make much use of PIE. But sshd can. I = personally >> would >>> like to see all of base's applications compiled as PIEs, but that's = a >> long >>> ways off. It took OpenBSD several years to accomplish that. Having >> certain >>> high-visibility applications (like sshd, inetd, etc) is a great = start. >>> Providing a framework for application developers to opt their = application >>> into PIE is another great start. >>>=20 >>> Those are my two cents. >>=20 >> OK. As long as i386 is still an important architecture, it can make >> sense to enable this on a per-binary basis if we don't want to have a >> discrepancy between archs. Also I buy your argument on /bin/ls but I >> was challenging to enable for the whole system because I wonder if >> there aren't some unexpected attack surfaces, besides the obvious = ones >> (servers). >>=20 >> Do you know what took so much time to OpenBSD? >=20 >=20 > In a private conversation with Theo, I realized that my recollection = of the > time it took OpenBSD to compile all of base as PIEs was wrong. Quoting = him: >=20 > "It took 5 people approximately 3 months to debug it, activate it, and > start shipping it the next release. That was on amd64, for all > dynamically linked binaries, except one (a gcc bug took some time to > find). The next architectures followed about 1 or 2 per 6-month > release." >=20 > Given that only one person has worked on this in the past (me) and now = the > task has been delegated to another (David Carlier), I think we're = doing > okay on our end. There's a lot of moving parts, and neither of us = fully > understand all of them completely. We're working on it in HardenedBSD, = in > the hardened/current/pie branch. >=20 > I'm thinking we might try for a WITH_PIE knob (and *not* use USE_PIE) = and > have certain high-profile applications opt-in to PIE until we work out = all > the details for everything en masse. Baptiste did bring up a good = point > with INTERNALLIB and I'm unsure of how we should handle that. WITH_PIE or WITHOUT_PIE controls, on a global basis, via the MK_PIE variable, whether or not the user wants to turn on this feature for = those program that can do PIE. Designating which programs do, or don=92t, use PIE simply must be done with a different variable. I posted a bit of = a rant about the current state of things that suggested a couple of alternatives as well as giving some history as to why some options aren=92t to be used and the history behind some of my reactions. :) For this reason, I think WITH_PIE, as I understand your proposal, likely isn=92t a good fit with other WITH_xxx variables used in the src tree today. Warner --Apple-Mail=_C9A81F84-205F-4468-B0E6-6F6B44558AF7 Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP using GPGMail -----BEGIN PGP SIGNATURE----- Comment: GPGTools - https://gpgtools.org iQIcBAEBCgAGBQJUQRyCAAoJEGwc0Sh9sBEAW7EQAKo+M1fXOG9+zpjbGsMMre+B T2q1Rmo5mUeXjrAX1s7dyraXp39O5XfnCDIQJj82pFF90L1M0kB8wm4trU9QDYEL rhAnVN/ajLYJ8Q89CwhWaW9di08VvciKLfJ3fLPjH3p+NqWBcuY46yiwAzsGpBL0 SDHMS148jW5xAkg2JAGuepanjQeVfjJZUIMO6i/f2jZVUfmupkpl8AqRp+cQiziC ALoxfc3bn1mD8ECXenQFiDzMmAN4fpN4gVaPGvM7YHfaDiEDJVlgJbK3iJqvHdBC vLM4/tvw1DhqF0cJ1drcGEAwafDNILEsCpMdNqzZ+UU5GuD9FG1DO0QyjFUtP8// P50O74Pw6v/oFVQWvwaUqzcQ39txsBgaBcevoO22GgQwwVTx+xX0tIpBDb2jJpnv JgrvjHoDMPePM7r44SaPQgPkntbVGbpjlNmL1o7jSBahkdkWHdkqqOmYZkk+MQ+C RPwB09CyQwavvqFI2NZ7w1FqOiguK0WeQG5VhYTcSzQJQTiv7EBLoikcw+HxkU7Y rEI69poq+zuL7fN7RFibxKnJt30eTXhuvI05/cn9cjZZW/7Uc1KY1FQ1DJTRnqS8 4fW8qhItoena+UXPjtlIUAIQa9HEc4OkgXM8unaEquBoli3RwxUa5xq6fwr6AmIz eOghcbHwfhbgM0R+YwA6 =cajQ -----END PGP SIGNATURE----- --Apple-Mail=_C9A81F84-205F-4468-B0E6-6F6B44558AF7--
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