Date: Tue, 5 Aug 2008 16:15:20 +0400 From: Stanislav Sedov <stas@FreeBSD.org> To: Kostik Belousov <kostikbel@gmail.com> Cc: Rui Paulo <rpaulo@freebsd.org>, current@freebsd.org, Peter Jeremy <peterjeremy@optushome.com.au>, Stanislav Sedov <stas@freebsd.org>, Poul-Henning Kamp <phk@phk.freebsd.dk>, Coleman Kane <cokane@freebsd.org> Subject: Re: cpuctl(formely devcpu) patch test request Message-ID: <20080805161520.90001117.stas@FreeBSD.org> In-Reply-To: <20080805115315.GE97161@deviant.kiev.zoral.com.ua> References: <10261.1212703949@critter.freebsd.dk> <20080606025533.8322ee08.stas@FreeBSD.org> <1212758604.1904.33.camel@localhost> <20080615230250.7f3efae4.stas@FreeBSD.org> <1213557999.1816.15.camel@localhost> <20080616204433.48ad9879.stas@FreeBSD.org> <e1309ba60806161110x5f774fcdic2f5c7b2e7bcb83e@mail.gmail.com> <20080616222740.5cdd9490.stas@FreeBSD.org> <1213641761.2184.0.camel@localhost> <20080805140324.9f53ba9b.stas@FreeBSD.org> <20080805115315.GE97161@deviant.kiev.zoral.com.ua>
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--Signature=_Tue__5_Aug_2008_16_15_20_+0400_jZV9k1g+v=MJpoQS Content-Type: text/plain; charset=US-ASCII Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, 5 Aug 2008 14:53:15 +0300 Kostik Belousov <kostikbel@gmail.com> mentioned: > On Tue, Aug 05, 2008 at 02:03:24PM +0400, Stanislav Sedov wrote: > > On Mon, 16 Jun 2008 14:42:41 -0400 > > Coleman Kane <cokane@FreeBSD.org> mentioned: > >=20 > > >=20 > > > Is it potentially "unsafe" to use RDMSR? > > > > >=20 > > Well, it might disclose some sensitive information, > > as well as create covert channels. E.g. some of the > > registers contains kernel thread pointers, etc; some > > of them undocumented. It won't be very wise to give > > access to the rdmsr feature to all users on a > > multi-user machine. > >=20 > > Sorry for this taking so long. You messages spotted > > a bug in my security model for this driver, so I've > > redone that. Now, the access to the rdmsr and cpuid > > features will be granted only if the caller has > > read permissions on the device, and wrmsr/update > > - only if he've opened the device for writing. > > This way you can provide fine-grained control to > > the driver features. > >=20 > > I've also added the cpucontrol utility which provided > > userland accesss to the driver, and allows to apply > > microcode updates. > >=20 > > The latest patch against HEAD is available here: > > ftp://ftp.SpringDaemons.com/dustheap/cpuctl.4.diff > >=20 > > Thanks! >=20 > --- a/sys/amd64/amd64/support.S > +++ b/sys/amd64/amd64/support.S > @@ -765,6 +765,7 @@ ENTRY(wrmsr_safe) > */ > ALIGN_TEXT > msr_onfault: > - movq $0,PCB_ONFAULT(%r8) > - movl $EFAULT,%eax > + movq PCPU(CURPCB),%r8 /* set fault handler */ > + movq $0,PCB_ONFAULT(%r8) > + movq $EFAULT,%rax > ret >=20 > movq $EFAULT,%rax is better to be replaced by movl, %eax. Amd64 specifies > automatic zeroing of the upper-half of the registers on the 32bit operati= on. >=20 Yeah, it seems that I thought about this initially, but decided that this was unsafe lately. Thanks for suggestion! There's a fixed version: ftp://ftp.SpringDaemons.com/dustheap/cpuctl.5.diff --=20 Stanislav Sedov ST4096-RIPE --Signature=_Tue__5_Aug_2008_16_15_20_+0400_jZV9k1g+v=MJpoQS Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (FreeBSD) iEYEARECAAYFAkiYRF0ACgkQK/VZk+smlYF7kwCdF/AwMolDqHnkV50Z0e3SS1yh fl8An31xxlMTsa29pIHdMzoTdeE7SPmM =5tYo -----END PGP SIGNATURE----- --Signature=_Tue__5_Aug_2008_16_15_20_+0400_jZV9k1g+v=MJpoQS--
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