linux-kernel - Re: [PATCH v34 12/24] x86/sgx: Add SGX_IOC_ENCLAVE

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Date:   Mon, 6 Jul 2020 20:29:15 -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, 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 v34 12/24] x86/sgx: Add SGX_IOC_ENCLAVE_CREATE

On Tue, Jul 07, 2020 at 06:01:52AM +0300, Jarkko Sakkinen wrote:
> +long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
> +{
> +	struct sgx_encl *encl = filep->private_data;
> +	int ret, encl_flags;
> +
> +	encl_flags = atomic_fetch_or(SGX_ENCL_IOCTL, &encl->flags);
> +	if (encl_flags & SGX_ENCL_IOCTL)
> +		return -EBUSY;

As called out in my belated feedback, SGX_ENCL_DEAD needs to be checked
here to prevent invoking ENCLS operations on a dead enclave.  If you're
splitting hairs, the check could technically be deferred until the next
patch, "Add SGX_IOC_ENCLAVE_ADD_PAGES", which is the first usage of
sgx_encl_destroy() from an ioctl(), but that seems a bit gratuitous.

> +
> +	switch (cmd) {
> +	case SGX_IOC_ENCLAVE_CREATE:
> +		ret = sgx_ioc_enclave_create(encl, (void __user *)arg);
> +		break;
> +	default:
> +		ret = -ENOIOCTLCMD;
> +		break;
> +	}
> +
> +	atomic_andnot(SGX_ENCL_IOCTL, &encl->flags);
> +	return ret;
> +}
> -- 
> 2.25.1
>