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Date: Fri, 13 Mar 2015 12:43:45 -0700 From: Nick Kralevich <nnk@...gle.com> To: oss-security@...ts.openwall.com Subject: Re: Vendor adoption of PIE INFO#934476 oss-security On Fri, Mar 13, 2015 at 10:19 AM, Daniel Micay <danielmicay@...il.com> wrote: > On 13/03/15 11:05 AM, Solar Designer wrote: >> On Thu, Mar 12, 2015 at 08:31:42PM -0700, Nick Kralevich wrote: >>> I wanted to provide a followup on this year-old thread. >> >> Thank you! >> >>> With the release of Android 5.0, Android has removed support for >>> non-PIE binaries [1] [2]. Attempting to run a non-PIE binary will >>> generate an error on Android. In this way, we ensure that all binaries >>> take full advantage of Android's ASLR implementation. >>> >>> This is just one of the many security enhancements added in Android >>> 5.*, and one that I hope other Linux distributions will pick up. >>> >>> [1] https://source.android.com/devices/tech/security/enhancements/enhancements50.html >>> [2] https://android.googlesource.com/platform/bionic/+/76e289c026f11126fc88841b3019fd5bb419bb67 > > Sadly, PIE is much less useful on Android right now. Every app and many > services are spawned from an initial zygote process without an exec, so > nearly everything has the same ASLR bases. It is great to see progress > in this space though. I hope to see the zygote process go away now that > ART and modern hardware makes it much less necessary - especially if a > process (or a pool) is pre-spawned during idle time. > > AFAIK, the change forbidding non-PIE binaries was backed out for the > official 5.0 release > (https://android.googlesource.com/platform/bionic/+/d81b3b275dff99561cbe5905ca63a1c72fa54a17). > I guess that was fixed in 5.1? I haven't looked into it yet. You are getting the dates of your patches out of order. There were three patches submitted in the following order: 2014-05-08: Remove support for non-PIE executables https://android.googlesource.com/platform/bionic/+/2aebf5429bb1241a3298b5b642d38f73124c2026 2014-06-19: Reenable support for non-PIE executables https://android.googlesource.com/platform/bionic/+/d81b3b275dff99561cbe5905ca63a1c72fa54a17 2014-07-03: Revert "Reenable support for non-PIE executables" https://android.googlesource.com/platform/bionic/+/76e289c026f11126fc88841b3019fd5bb419bb67 The last patch is definitely in Android 5.0, and was never backed out. ~/aosp/bionic/linker$ git tag --contains 76e289c026f11126fc88841b3019fd5bb419bb67 android-5.0.0_r1 android-5.0.0_r2 android-5.0.0_r3 android-5.0.0_r4 android-5.0.0_r5 android-5.0.0_r5.1 android-5.0.0_r6 android-5.0.0_r7 android-5.0.1_r1 android-5.0.2_r1 android-5.1.0_r1 android-l-preview_r2 android-wear-5.0.0_r1 > >> I brought this to Twitter, and here's a comment by Rich Felker: >> >> <solardiz> Android 5.0 "has removed support for non-PIE binaries. Attempting to run a non-PIE binary will generate an error" http://www.openwall.com/lists/oss-security/2015/03/13/1 >> <@RichFelker> @solardiz Guess that means no emacs on Android... >> <@solardiz> @RichFelker Why, can't one build Emacs as PIE? >> <@RichFelker> @solardiz The whole dumper issue. The final emacs binary is a dump of an emacs with a lisp heap full of pointers and no relocation data. > > FWIW, I think various distributions are going to enable it once the PIE > by default patches land: > > https://www.mail-archive.com/gcc-patches@gcc.gnu.org/msg105030.html > > There has been no luck getting someone to review them, so they missed > the GCC 5 freeze deadline despite being ready before then. > > I proposed that we enable it by default on Arch via wrapper scripts, but > it was rejected in favour of waiting for this patch to land. An OpenSUSE > developer also voiced interest in the patches on the GCC mailing list. > It just needs a committer who feels like reviewing it. > -- Nick Kralevich | Android Security | nnk@...gle.com | 650.214.4037
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