linux-kernel - Re: [PATCH V3 14/30] x86/sgx: Support restricting of enclave page permissions

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Date:   Wed, 6 Apr 2022 10:51:44 -0700
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     Jarkko Sakkinen <jarkko@...nel.org>, <dave.hansen@...ux.intel.com>,
        <tglx@...utronix.de>, <bp@...en8.de>, <luto@...nel.org>,
        <mingo@...hat.com>, <linux-sgx@...r.kernel.org>, <x86@...nel.org>
CC:     <seanjc@...gle.com>, <kai.huang@...el.com>,
        <cathy.zhang@...el.com>, <cedric.xing@...el.com>,
        <haitao.huang@...el.com>, <mark.shanahan@...el.com>,
        <hpa@...or.com>, <linux-kernel@...r.kernel.org>,
        <nathaniel@...fian.com>
Subject: Re: [PATCH V3 14/30] x86/sgx: Support restricting of enclave page
 permissions

Hi Jarkko,

On 4/6/2022 12:30 AM, Jarkko Sakkinen wrote:
> On Tue, 2022-04-05 at 11:59 -0700, Reinette Chatre wrote:


>> I plan to replace the current "secinfo" field in struct sgx_enclave_restrict_permissions
>> with a new "permissions" field that contain only the permissions. Please let
>> me know if you have concerns with this (I also discuss this more in reply to
>> your other message related to the page type change ioctl()).
> 
> I'm cool with it but if it is named as "permissions", then 
> it is already software-defined entity, i.e. meaning just that
> have this check in place in the ioctl:
> 
> if (addp->permissions & !(PROT_READ | PROT_WRITE | PROT_EXEC))
> 	return -EINVAL;
> 

I assume that we do still want to ensure that
PROT_READ is always set.

I was planning to keep it in the "SGX language" since
this is about changing EPCM permissions with values from
a runtime understanding SGX permissions in secinfo that will
be provided to hardware understanding SGX permissions in
secinfo.

Thus:

if (params.permissions & ~SGX_SECINFO_PERMISSION_MASK)
	return -EINVAL;

if (!(params.permissions & SGX_SECINFO_R))
	return -EINVAL;


Reinette