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SubjectRe: [PATCH 3/3] nvme: Check if drive is locked using ATA Security
On Sun, Jun 19, 2016 at 04:06:34PM -0700, Jethro Beekman wrote:
> Signed-off-by: Jethro Beekman <kernel@jbeekman.nl>
> ---
> drivers/nvme/host/core.c | 49 +++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 48 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index da027ed..0164122 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -1389,10 +1389,57 @@ int nvme_security_recv(struct nvme_ctrl *dev, u8 protocol, void *buf,
> return nvme_submit_sync_cmd(dev->admin_q, &c, buf, len);
> }
>
> +#define OACS_SECURITY (1<<0)
> +#define SCSI_SECURITY_PROTOCOL_ATA_SECURITY 0xef
> +#define ATA_SECURITY_LOCKED 0x4

It would be great to have this out in a header or maybe rather
headers. OACS_SECURITY should go into nvme.h, we probably should have a
new header for the SCSI security protocols (e.g.
include/scsi/scsi_security.h ?), and I'm not sure what to do with
ATA_SECURITY_LOCKED - maybe just add it to scsi_security.h for now until
we get a more fully blown ata security implementation that even includes
ATA :))

> static bool nvme_security_is_locked(struct nvme_ctrl *ctrl,
> struct nvme_id_ctrl *id)
> {
> - return false;
> + int err;
> + unsigned int i;
> + bool found;
> + u8 protocols[256+8]; /* 8 byte hdr + max number of possible protocols */

Please define a constant for the length in the new scsi_security.h
header.

> + /* find ata security protocol */
> + n = be16_to_cpup((__be16 *)(protocols+6));

Just use get_unaligned_be16 that operates directly on the char
array, similar to how we do in lots of places in the SCSI stack.

> + for (i = 0; i <= n; i++) {
> + if (protocols[8+i] == SCSI_SECURITY_PROTOCOL_ATA_SECURITY) {
> + found = true;
> + break;
> + }
> + }

I wonder if it might be a good idea to change the structure here a bit
to allow for future other protocols and have each protocol in a helper,
e.g. do something like

for (i = 0; i <= n; i++) {
switch (protocols[8 + i]) {
case SCSI_SECURITY_PROTOCOL_ATA_SECURITY:
locked |= nvme_security_ata_is_locked()
break;
default:
break;
}

> + return ata_security[1] == 0xe && (ata_security[9]&ATA_SECURITY_LOCKED);

Can we have a sumbolic name for the 0xe? Also please always add spaces
around your operators.

But after all this nitpicking the general idea looks fine, thanks a lot
for the patch!

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