From mboxrd@z Thu Jan 1 00:00:00 1970 Reply-To: kernel-hardening@lists.openwall.com Message-ID: <1470328352.22643.110.camel@gmail.com> From: Daniel Micay Date: Thu, 04 Aug 2016 12:32:32 -0400 In-Reply-To: <20160804161000.GA11673@leverpostej> References: <20160802095243.GD6862@twins.programming.kicks-ass.net> <20160802203037.GC6879@twins.programming.kicks-ass.net> <87shulix2z.fsf@x220.int.ebiederm.org> <1470252976.22643.41.camel@gmail.com> <20160804102854.GB4483@leverpostej> <1470318323.22643.70.camel@gmail.com> <20160804141109.GM6879@twins.programming.kicks-ass.net> <1470325468.22643.95.camel@gmail.com> <20160804161000.GA11673@leverpostej> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-6mNzZXwJf1XajooxiGYw" Mime-Version: 1.0 Subject: Re: [kernel-hardening] Re: [PATCH 1/2] security, perf: allow further restriction of perf_event_open To: kernel-hardening@lists.openwall.com Cc: Peter Zijlstra , Kees Cook , Jeff Vander Stoep , Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , "linux-doc@vger.kernel.org" , LKML , Jonathan Corbet List-ID: --=-6mNzZXwJf1XajooxiGYw Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2016-08-04 at 17:10 +0100, Mark Rutland wrote: > On Thu, Aug 04, 2016 at 11:44:28AM -0400, Daniel Micay wrote: > >=20 > > Qualcomm's drivers might be lower quality than core kernel code, but > > they're way above the baseline set by mainline kernel drivers... >=20 > I don't think that's true for the arm/arm64 perf code. The baseline architecture support is essentially core kernel code. I agree it's much better than the SoC vendor code. You're spending a lot of time auditing, fuzzing and improving the code in general, which is not true for most drivers. They don't get that attention. > I think we've done a reasonable job of testing and fixing those, along > with core infrastructure issues. The perf fuzzer runs for a very long > time on a mainline kernel without issues, while on my Nexus 5x I get a > hard lockup after ~85 seconds (and prior to the last android update > the > lockup was instantaneous). > > From my personal experience (and as above), and talking specifically > about PMU drivers, I think that the opposite is true. This is not to > say > there aren't issues; I would not be surprised if there are. But it's > disingenuous to say that mainline code is worse than that which exists > in a vendor kernel when the latter is demonstrably much easier to > break > than the former. I wasn't talking specifically about perf. > If there are issues you are aware of, please report them. If those > issues only exist in non-upstream code, then the applicable concerns > are > somewhat different (though certainly still exist). I'm not going to do volunteer work for a corporation. I've learned that lesson after spending years doing it. > But please, let's frame the argument to match reality. The argument is framed in reality. Stating that it now often takes a few hours to find a vulnerability with the unaltered, widely known public perf fuzzer is not impressive. It's really an argument for claiming that it's a significant security issue. --=-6mNzZXwJf1XajooxiGYw Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIzBAABCAAdBQJXo24gFhxkYW5pZWxtaWNheUBnbWFpbC5jb20ACgkQ+ecS5Zr1 8ir1Hg//WBuCvmojXN//kOkxYRzNY5nBo/ijvVlpFihf8sdKI1nqJCiletPnSH7F DTwwktn38oo+G8h5cqWpYP1eKLmQ9KSTl7DbCaiCLJRME6hRXD2nrjcyko3hXLSk tfkKxbiVzO++V8J7hlrOomUZFO2+r+j2NRQeEkd1aGSje5fkFGYci7VMRhiu/mco o+NnaLejWFIy6IHym7K5mCSPUbMiXNCMvo1WgUaabSm2h3ZC/5yrLdDbXAoD4RJm ijH5B9+yPThc5e9gJLgPaOkMC0+Oy5RXBF7X7vSUZnmVWY+GdY7UzstV7lemVI9A bO0JkFrifo8O56mpik111h3gDBM5enZigVH/szERgaWzO+MXUzPfQWsub5SSIND2 BDOODlCtbhDoKoCqnSZ4zh7VKCaqfE3/KSGKguI+4h5HDUsudAaXp82dGg8/jTL3 +0VF8/xi22gZSQZXrK5yt2vT9BY9CmQ/iFbR7YcQIFi/wgF/ARUcTdPch1dayySf ggrsqziBDFXb7bT3N9nGU0oo+XCxOIU/2y4xvND1w7p1iNWbSrtX3gflQV7dXWI+ JxgzBBg1s/wzhAGN/oMFUwqZKA5O8aWFh13ZudLevLUyp4R6UzpIRNAl0TEdzCQ0 eTSmha4aUHZ2eKpkivm6/h2XGyhf0oKc0OTv5ebI/4+iOFlCzPs= =SnIe -----END PGP SIGNATURE----- --=-6mNzZXwJf1XajooxiGYw--