Re: [Part2 PATCH v5.1 12.7/31] crypto: ccp: Implement SEV_PEK_CSR ioctl command

[Brijesh Singh <brijesh.singh@amd.com>]

On 10/12/17 2:53 PM, Borislav Petkov wrote:
...

> Ok, a couple of things here:
>
> * Move the checks first and the allocations second so that you allocate
> memory only after all checks have been passed and you don't allocate
> pointlessly.


I assume you mean performing the SEV state check before allocating the
memory for the CSR blob, right ? In my patches, I typically perform all
the SW specific checks and allocation before invoking the HW routines.
Handling the PSP commands will take longer compare to kmalloc() or
access_ok() etc. If its not a big deal then I would prefer to keep that
way.


>
> * That:
>
>         if (state == SEV_STATE_WORKING) {
>                 ret = -EBUSY;
>                 goto e_free_blob;
>         } else if (state == SEV_STATE_UNINIT) {
>                 ret = sev_firmware_init(&argp->error);
>                 if (ret)
>                         goto e_free_blob;
>                 do_shutdown = 1;
>         }
>
> is a repeating pattern. Perhaps it should be called
> sev_firmware_reinit() and called by other functions.


> * The rest is simplifications and streamlining.
>
> ---
> diff --git a/drivers/crypto/ccp/psp-dev.c b/drivers/crypto/ccp/psp-dev.c
> index e3ee68afd068..d41f5448a25b 100644
> --- a/drivers/crypto/ccp/psp-dev.c
> +++ b/drivers/crypto/ccp/psp-dev.c
> @@ -302,33 +302,30 @@ static int sev_ioctl_pek_csr(struct sev_issue_cmd *argp)
>  	int ret, state;
>  	void *blob;
>  
> -	if (copy_from_user(&input, (void __user *)(uintptr_t)argp->data,
> -			   sizeof(struct sev_user_data_pek_csr)))
> +	if (copy_from_user(&input, (void __user *)argp->data, sizeof(input)))
> +		return -EFAULT;
> +
> +	if (!input.address)
> +		return -EINVAL;
> +
> +	/* allocate a physically contiguous buffer to store the CSR blob */
> +	if (!access_ok(VERIFY_WRITE, input.address, input.length) ||
> +	    input.length > SEV_FW_BLOB_MAX_SIZE)
>  		return -EFAULT;
>  
>  	data = kzalloc(sizeof(*data), GFP_KERNEL);
>  	if (!data)
>  		return -ENOMEM;
>  
> -	/* allocate a temporary physical contigous buffer to store the CSR blob */
> -	blob = NULL;
> -	if (input.address) {
> -		if (!access_ok(VERIFY_WRITE, input.address, input.length) ||
> -		    input.length > SEV_FW_BLOB_MAX_SIZE) {
> -			ret = -EFAULT;
> -			goto e_free;
> -		}
> -
> -		blob = kmalloc(input.length, GFP_KERNEL);
> -		if (!blob) {
> -			ret = -ENOMEM;
> -			goto e_free;
> -		}
> -
> -		data->address = __psp_pa(blob);
> -		data->len = input.length;
> +	blob = kmalloc(input.length, GFP_KERNEL);
> +	if (!blob) {
> +		ret = -ENOMEM;
> +		goto e_free;
>  	}
>  
> +	data->address = __psp_pa(blob);
> +	data->len = input.length;
> +
>  	ret = sev_platform_get_state(&state, &argp->error);
>  	if (ret)
>  		goto e_free_blob;
> @@ -349,25 +346,23 @@ static int sev_ioctl_pek_csr(struct sev_issue_cmd *argp)
>  		do_shutdown = 1;
>  	}
>  
> -	ret = sev_handle_cmd(SEV_CMD_PEK_CSR, data, &argp->error);
> +	ret = sev_do_cmd(SEV_CMD_PEK_CSR, data, &argp->error);
>  
>  	input.length = data->len;
>  
>  	/* copy blob to userspace */
> -	if (blob &&
> -	    copy_to_user((void __user *)(uintptr_t)input.address,
> -			blob, input.length)) {
> +	if (copy_to_user((void __user *)input.address, blob, input.length)) {
>  		ret = -EFAULT;
>  		goto e_shutdown;
>  	}
>  
> -	if (copy_to_user((void __user *)(uintptr_t)argp->data, &input,
> -			 sizeof(struct sev_user_data_pek_csr)))
> +	if (copy_to_user((void __user *)argp->data, &input, sizeof(input)))
>  		ret = -EFAULT;
>  
>  e_shutdown:
>  	if (do_shutdown)
> -		sev_handle_cmd(SEV_CMD_SHUTDOWN, 0, NULL);
> +		ret = sev_do_cmd(SEV_CMD_SHUTDOWN, 0, NULL);
> +
>  e_free_blob:
>  	kfree(blob);
>  e_free:
> @@ -408,10 +403,10 @@ static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg)
>  		ret = sev_ioctl_pdh_gen(&input);
>  		break;
>  
> -	case SEV_PEK_CSR: {
> +	case SEV_PEK_CSR:
>  		ret = sev_ioctl_pek_csr(&input);
>  		break;
> -	}
> +
>  	default:
>  		ret = -EINVAL;
>  		goto out;
>