linux-kernel - Re: [PATCH v33 11/21] x86/sgx: Linux Enclave Driver

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Message-ID: <20200702035902.GC1819@linux.intel.com>
Date:   Wed, 1 Jul 2020 20:59:02 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     x86@...nel.org, linux-sgx@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        Jethro Beekman <jethro@...tanix.com>,
        Haitao Huang <haitao.huang@...ux.intel.com>,
        Chunyang Hui <sanqian.hcy@...fin.com>,
        Jordan Hand <jorhand@...ux.microsoft.com>,
        Nathaniel McCallum <npmccallum@...hat.com>,
        Seth Moore <sethmo@...gle.com>,
        Suresh Siddha <suresh.b.siddha@...el.com>,
        akpm@...ux-foundation.org, andriy.shevchenko@...ux.intel.com,
        asapek@...gle.com, bp@...en8.de, cedric.xing@...el.com,
        chenalexchen@...gle.com, conradparker@...gle.com,
        cyhanish@...gle.com, dave.hansen@...el.com, haitao.huang@...el.com,
        josh@...htriplett.org, kai.huang@...el.com, kai.svahn@...el.com,
        kmoy@...gle.com, ludloff@...gle.com, luto@...nel.org,
        nhorman@...hat.com, puiterwijk@...hat.com, rientjes@...gle.com,
        tglx@...utronix.de, yaozhangx@...gle.com
Subject: Re: [PATCH v33 11/21] x86/sgx: Linux Enclave Driver

On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
> +static int sgx_validate_secs(const struct sgx_secs *secs,
> +			     unsigned long ssaframesize)
> +{
> +	if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size))
> +		return -EINVAL;
> +
> +	if (secs->base & (secs->size - 1))
> +		return -EINVAL;
> +
> +	if (secs->miscselect & sgx_misc_reserved_mask ||
> +	    secs->attributes & sgx_attributes_reserved_mask ||
> +	    secs->xfrm & sgx_xfrm_reserved_mask)
> +		return -EINVAL;
> +
> +	if (secs->attributes & SGX_ATTR_MODE64BIT) {
> +		if (secs->size > sgx_encl_size_max_64)
> +			return -EINVAL;
> +	} else if (secs->size > sgx_encl_size_max_32)
> +		return -EINVAL;

These should be >=, not >, the SDM uses one of those fancy ≥ ligatures.

Internal versions use more obvious pseudocode, e.g.:

    if ((DS:TMP_SECS.ATTRIBUTES.MODE64BIT = 1) AND
        (DS:TMP_SECS.SIZE AND (~((1 << CPUID.18.0:EDX[15:8]) – 1)))
    {
        #GP(0);
    }

> +
> +	if (!(secs->xfrm & XFEATURE_MASK_FP) ||
> +	    !(secs->xfrm & XFEATURE_MASK_SSE) ||
> +	    (((secs->xfrm >> XFEATURE_BNDREGS) & 1) !=
> +	     ((secs->xfrm >> XFEATURE_BNDCSR) & 1)))
> +		return -EINVAL;
> +
> +	if (!secs->ssa_frame_size || ssaframesize > secs->ssa_frame_size)
> +		return -EINVAL;
> +
> +	if (memchr_inv(secs->reserved1, 0, sizeof(secs->reserved1)) ||
> +	    memchr_inv(secs->reserved2, 0, sizeof(secs->reserved2)) ||
> +	    memchr_inv(secs->reserved3, 0, sizeof(secs->reserved3)) ||
> +	    memchr_inv(secs->reserved4, 0, sizeof(secs->reserved4)))
> +		return -EINVAL;
> +
> +	return 0;
> +}