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Subject: Re: [PATCH V4 00/31] x86/sgx and selftests/sgx: Support SGX2
From:   Jarkko Sakkinen <jarkko@kernel.org>
To:     Reinette Chatre <reinette.chatre@intel.com>, jethro@fortanix.com
Cc:     "Dhanraj, Vijay" <vijay.dhanraj@intel.com>,
        "dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "bp@alien8.de" <bp@alien8.de>,
        "Lutomirski, Andy" <luto@kernel.org>,
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        "x86@kernel.org" <x86@kernel.org>,
        "shuah@kernel.org" <shuah@kernel.org>,
        "linux-kselftest@vger.kernel.org" <linux-kselftest@vger.kernel.org>,
        "Shanahan, Mark" <mark.shanahan@intel.com>,
        "Christopherson,, Sean" <seanjc@google.com>,
        "Huang, Kai" <kai.huang@intel.com>,
        "Zhang, Cathy" <cathy.zhang@intel.com>,
        "Xing, Cedric" <cedric.xing@intel.com>,
        "Huang, Haitao" <haitao.huang@intel.com>,
        "hpa@zytor.com" <hpa@zytor.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Date:   Fri, 22 Apr 2022 16:17:11 +0300
In-Reply-To: <YmJyYwp9UHRLWaTw@kernel.org>
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On Fri, 2022-04-22 at 12:16 +0300, Jarkko Sakkinen wrote:
> On Thu, Apr 21, 2022 at 08:29:31PM -0700, Reinette Chatre wrote:
> > Hi Vijay and Mark,
> >=20
> > On 4/21/2022 4:46 PM, Dhanraj, Vijay wrote:
> > > Hi All,
> > >=20
> > > I evaluated V4 patch changes with Gramine and ran into an issue when =
trying to set EPC page permission to PROT_NONE. It looks like with V3 patch=
 series a change was introduced which requires
> > > kernel to have at least R permission when calling RESTRICT IOCTL. Thi=
s change was done under the assumption that EPCM requires at least R permis=
sion for EMODPE/EACCEPT to succeed. But when
> > > testing with V2 version, EACCEPT worked fine with page permission set=
 to PROT_NONE.=20
> > >=20
> > > Thanks to @Shanahan, Mark for confirming that EPCM does not need to h=
ave R value to allow EACCEPT or EMODPE. Given this, can we please revert th=
is change?
> > >=20
> >=20
> > Thank you very much for pointing this out. I can revert the change
> > to what was done in V2 where the only check is to ensure that W require=
s R.
> > This is a requirement of EMODPR. Could you please check if this snippet
> > results in things working for you again?
> >=20
> > ---8<---
> > diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/=
ioctl.c
> > index 83674d054c13..7c7c8a61196e 100644
> > --- a/arch/x86/kernel/cpu/sgx/ioctl.c
> > +++ b/arch/x86/kernel/cpu/sgx/ioctl.c
> > @@ -855,12 +855,8 @@ static long sgx_ioc_enclave_restrict_permissions(s=
truct sgx_encl *encl,
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0if (params.permissions =
& ~SGX_SECINFO_PERMISSION_MASK)
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0return -EINVAL;
> > =C2=A0
> > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0/*
> > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * Read access is required f=
or the enclave to be able to use the page.
> > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * SGX instructions like ENC=
LU[EMODPE] and ENCLU[EACCEPT] require
> > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * read access.
> > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 */
> > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0if (!(params.permissions & S=
GX_SECINFO_R))
> > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0if ((params.permissions & SG=
X_SECINFO_W) &&
> > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 !(params.=
permissions & SGX_SECINFO_R))
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0return -EINVAL;
> > =C2=A0
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0if (params.result || pa=
rams.count)
>=20
> Just adding that it's fine for me to revert this.

Jethro, I thought it would be also good to get yor view on the current
series. Is this something that your platform can live with?

BR, Jarkko