linux-kernel - Re: [PATCH v2 2/3] libnvdimm/security: the 'security' attr never show 'overwrite' state

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Date:   Thu, 6 Aug 2020 12:26:26 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Jane Chu <jane.chu@...cle.com>
Cc:     dan.j.williams@...el.com, vishal.l.verma@...el.com,
        dave.jiang@...el.com, jmoyer@...hat.com, linux-nvdimm@...ts.01.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/3] libnvdimm/security: the 'security' attr never
 show 'overwrite' state

On Mon, Aug 03, 2020 at 04:41:38PM -0600, Jane Chu wrote:
> 'security' attribute displays the security state of an nvdimm.
> During normal operation, the nvdimm state maybe one of 'disabled',
> 'unlocked' or 'locked'.  When an admin issues
>   # ndctl sanitize-dimm nmem0 --overwrite
> the attribute is expected to change to 'overwrite' until the overwrite
> operation completes.
> 
> But tests on our systems show that 'overwrite' is never shown during
> the overwrite operation. i.e.
>   # cat /sys/devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0012:00/ndbus0/nmem0/security
>   unlocked
> the attribute remain 'unlocked' through out the operation, consequently
> "ndctl wait-overwrite nmem0" command doesn't wait at all.
> 
> The driver tracks the state in 'nvdimm->sec.flags': when the operation
> starts, it adds an overwrite bit to the flags; and when the operation
> completes, it removes the bit. Hence security_show() should check the
> 'overwrite' bit first, in order to indicate the actual state when multiple
> bits are set in the flags.
> 
> Signed-off-by: Jane Chu <jane.chu@...cle.com>
> Reviewed-by: Dave Jiang <dave.jiang@...el.com>

Reviewed-by: Ira Weiny <ira.weiny@...el.com>

> ---
>  drivers/nvdimm/dimm_devs.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c
> index b7b77e8..5d72026 100644
> --- a/drivers/nvdimm/dimm_devs.c
> +++ b/drivers/nvdimm/dimm_devs.c
> @@ -363,14 +363,14 @@ __weak ssize_t security_show(struct device *dev,
>  {
>  	struct nvdimm *nvdimm = to_nvdimm(dev);
>  
> +	if (test_bit(NVDIMM_SECURITY_OVERWRITE, &nvdimm->sec.flags))
> +		return sprintf(buf, "overwrite\n");
>  	if (test_bit(NVDIMM_SECURITY_DISABLED, &nvdimm->sec.flags))
>  		return sprintf(buf, "disabled\n");
>  	if (test_bit(NVDIMM_SECURITY_UNLOCKED, &nvdimm->sec.flags))
>  		return sprintf(buf, "unlocked\n");
>  	if (test_bit(NVDIMM_SECURITY_LOCKED, &nvdimm->sec.flags))
>  		return sprintf(buf, "locked\n");
> -	if (test_bit(NVDIMM_SECURITY_OVERWRITE, &nvdimm->sec.flags))
> -		return sprintf(buf, "overwrite\n");
>  	return -ENOTTY;
>  }
>  
> -- 
> 1.8.3.1
>