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SubjectRE: [RFC PATCH 3/9] x86/sgx: Allow userspace to add multiple pages in single ioctl()
Date
> From: Christopherson, Sean J
> Sent: Friday, May 31, 2019 4:32 PM
>
> +/**
> + * sgx_ioc_enclave_add_pages - handler for %SGX_IOC_ENCLAVE_ADD_PAGES
> + *
> + * @filep: open file to /dev/sgx
> + * @cmd: the command value
> + * @arg: pointer to an &sgx_enclave_add_page instance
> + *
> + * Add a range of pages to an uninitialized enclave (EADD), and
> +optionally
> + * extend the enclave's measurement with the contents of the page (EEXTEND).
> + * The range of pages must be virtually contiguous. The SECINFO and
> + * measurement maskare applied to all pages, i.e. pages with different
> + * properties must be added in separate calls.
> + *
> + * EADD and EEXTEND are done asynchronously via worker threads. A
> +successful
> + * sgx_ioc_enclave_add_page() only indicates the pages have been added
> +to the
> + * work queue, it does not guarantee adding the pages to the enclave
> +will
> + * succeed.
> + *
> + * Return:
> + * 0 on success,
> + * -errno otherwise
> + */
> +static long sgx_ioc_enclave_add_pages(struct file *filep, unsigned int cmd,
> + unsigned long arg)
> +{
> + struct sgx_enclave_add_pages *addp = (void *)arg;
> + struct sgx_encl *encl = filep->private_data;
> + struct sgx_secinfo secinfo;
> + unsigned int i;
> + int ret;
> +
> + if (copy_from_user(&secinfo, (void __user *)addp->secinfo,
> + sizeof(secinfo)))
> + return -EFAULT;
> +
> + for (i = 0, ret = 0; i < addp->nr_pages && !ret; i++) {
> + if (signal_pending(current))
> + return -ERESTARTSYS;

If interrupted, how would user mode code know how many pages have been EADD'ed?

> +
> + if (need_resched())
> + cond_resched();
> +
> + ret = sgx_encl_add_page(encl, addp->addr + i*PAGE_SIZE,
> + addp->src + i*PAGE_SIZE,
> + &secinfo, addp->mrmask);
> + }
> return ret;
> }
>
> @@ -823,8 +845,8 @@ long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
> case SGX_IOC_ENCLAVE_CREATE:
> handler = sgx_ioc_enclave_create;
> break;
> - case SGX_IOC_ENCLAVE_ADD_PAGE:
> - handler = sgx_ioc_enclave_add_page;
> + case SGX_IOC_ENCLAVE_ADD_PAGES:
> + handler = sgx_ioc_enclave_add_pages;
> break;
> case SGX_IOC_ENCLAVE_INIT:
> handler = sgx_ioc_enclave_init;
> --
> 2.21.0

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