linux-kernel - Re: [PATCH] x86/sgx: Allows ioctl PROVISION to execute before CREATE

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Message-ID: <YAc7h3zQR06eWPhZ@google.com>
Date:   Tue, 19 Jan 2021 12:05:27 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Tianjia Zhang <tianjia.zhang@...ux.alibaba.com>
Cc:     Jarkko Sakkinen <jarkko@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Shuah Khan <shuah@...nel.org>, haitao.huang@...el.com,
        Kai Huang <kai.huang@...el.com>, x86@...nel.org,
        linux-sgx@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
        Jia Zhang <zhang.jia@...ux.alibaba.com>
Subject: Re: [PATCH] x86/sgx: Allows ioctl PROVISION to execute before CREATE

On Mon, Jan 18, 2021, Tianjia Zhang wrote:
> In function sgx_encl_create(), the logic of directly assigning
> value to attributes_mask determines that the call to
> SGX_IOC_ENCLAVE_PROVISION must be after the command of
> SGX_IOC_ENCLAVE_CREATE. If change this assignment statement to
> or operation, the PROVISION command can be executed earlier and
> more flexibly.
> 
> Reported-by: Jia Zhang <zhang.jia@...ux.alibaba.com>
> Signed-off-by: Tianjia Zhang <tianjia.zhang@...ux.alibaba.com>
> ---
>  arch/x86/kernel/cpu/sgx/ioctl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
> index f45957c05f69..0ca3fc238bc2 100644
> --- a/arch/x86/kernel/cpu/sgx/ioctl.c
> +++ b/arch/x86/kernel/cpu/sgx/ioctl.c
> @@ -108,7 +108,7 @@ static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs)
>  	encl->base = secs->base;
>  	encl->size = secs->size;
>  	encl->attributes = secs->attributes;
> -	encl->attributes_mask = SGX_ATTR_DEBUG | SGX_ATTR_MODE64BIT | SGX_ATTR_KSS;
> +	encl->attributes_mask |= SGX_ATTR_DEBUG | SGX_ATTR_MODE64BIT | SGX_ATTR_KSS;

Alternatively, move the existing code to sgx_open()?  Initializing the field
when the encl object is allocated feels more correct.

>  	/* Set only after completion, as encl->lock has not been taken. */
>  	set_bit(SGX_ENCL_CREATED, &encl->flags);
> -- 
> 2.19.1.3.ge56e4f7
>