linux-kernel - Re: [PATCH v14 15/19] platform/x86: Intel SGX driver

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Date:   Thu, 04 Oct 2018 11:01:17 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>, x86@...nel.org,
        platform-driver-x86@...r.kernel.org
Cc:     dave.hansen@...el.com, nhorman@...hat.com, npmccallum@...hat.com,
        serge.ayoun@...el.com, shay.katz-zamir@...el.com,
        linux-sgx@...r.kernel.org, andriy.shevchenko@...ux.intel.com,
        Suresh Siddha <suresh.b.siddha@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v14 15/19] platform/x86: Intel SGX driver

On Tue, 2018-09-25 at 16:06 +0300, Jarkko Sakkinen wrote:
> Intel Software Guard eXtensions (SGX) is a set of CPU instructions that
> can be used by applications to set aside private regions of code and
> data. The code outside the enclave is disallowed to access the memory
> inside the enclave by the CPU access control.
> 
> SGX driver provides a ioctl API for loading and initializing enclaves.
> Address range for enclaves is reserved with mmap() and they are
> destroyed with munmap(). Enclave construction, measurement and
> initialization is done with the provided the ioctl API.

...

> +/**
> + * sgx_ioc_enclave_init - handler for %SGX_IOC_ENCLAVE_INIT
> + *
> + * @filep:	open file to /dev/sgx
> + * @cmd:	the command value
> + * @arg:	pointer to an &sgx_enclave_init instance
> + *
> + * Flushes the remaining enqueued EADD operations and performs EINIT. Does not
> + * allow the EINITTOKENKEY attribute for an enclave.
> + *
> + * Return:
> + *   0 on success,
> + *   SGX error code on EINIT failure,
> + *   -errno otherwise
> + */
> +static long sgx_ioc_enclave_init(struct file *filep, unsigned int cmd,
> +				 unsigned long arg)
> +{
> +	struct sgx_enclave_init *initp = (struct sgx_enclave_init *)arg;
> +	struct sgx_sigstruct *sigstruct;
> +	struct sgx_einittoken *einittoken;
> +	struct sgx_encl *encl;
> +	struct page *initp_page;
> +	int ret;
> +
> +	initp_page = alloc_page(GFP_HIGHUSER);
> +	if (!initp_page)
> +		return -ENOMEM;
> +
> +	sigstruct = kmap(initp_page);
> +	einittoken = (struct sgx_einittoken *)
> +		((unsigned long)sigstruct + PAGE_SIZE / 2);
> +	memset(einittoken, 0, sizeof(*einittoken));
> +
> +	ret = copy_from_user(sigstruct, (void __user *)initp->sigstruct,
> +			     sizeof(*sigstruct));
> +	if (ret)
> +		goto out;
> +	if (sigstruct->attributes & SGX_ATTR_EINITTOKENKEY) {
> +		ret = EINVAL;

This should be "ret = -EINVAL".

> +		goto out;
> +	}
> +
> +	ret = sgx_encl_get(initp->addr, &encl);
> +	if (ret)
> +		goto out;
> +
> +	ret = sgx_encl_init(encl, sigstruct, einittoken);
> +
> +	kref_put(&encl->refcount, sgx_encl_release);
> +
> +out:
> +	kunmap(initp_page);
> +	__free_page(initp_page);
> +	return ret;
> +}