Re: [PATCH v4 13/16] block: sed-opal: check size of shadow mbr

[David Kozub <zub@xxxxxxxxxxxxxxxxxx>]

On Fri, 8 Feb 2019, Derrick, Jonathan wrote:

> On Fri, 2019-02-01 at 21:50 +0100, David Kozub wrote:
> > From: Jonas Rabenstein <jonas.rabenstein@xxxxxxxxxxxxxxxxxxxxxxx>
> >
> > Check whether the shadow mbr does fit in the provided space on the
> > target. Also a proper firmware should handle this case and return an
> > error we may prevent problems or even damage with crappy firmwares.
> >
> > Signed-off-by: Jonas Rabenstein <jonas.rabenstein@xxxxxxxxxxxxxxxxxxxxxxx>
> > Reviewed-by: Scott Bauer <sbauer@xxxxxxxxxxxxxx>
> > ---
> >  block/opal_proto.h | 16 ++++++++++++++++
> >  block/sed-opal.c   | 39 +++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 55 insertions(+)
> >
> > diff --git a/block/opal_proto.h b/block/opal_proto.h
> > index b6e352cfe982..5e8df3245eb0 100644
> > --- a/block/opal_proto.h
> > +++ b/block/opal_proto.h
> > @@ -106,6 +106,7 @@ enum opal_uid {
> >  	OPAL_ENTERPRISE_BANDMASTER0_UID,
> >  	OPAL_ENTERPRISE_ERASEMASTER_UID,
> >  	/* tables */
> > +	OPAL_TABLE_TABLE,
> >  	OPAL_LOCKINGRANGE_GLOBAL,
> >  	OPAL_LOCKINGRANGE_ACE_RDLOCKED,
> >  	OPAL_LOCKINGRANGE_ACE_WRLOCKED,
> > @@ -160,6 +161,21 @@ enum opal_token {
> >  	OPAL_STARTCOLUMN = 0x03,
> >  	OPAL_ENDCOLUMN = 0x04,
> >  	OPAL_VALUES = 0x01,
> > +	/* table table */
> > +	OPAL_TABLE_UID = 0x00,
> > +	OPAL_TABLE_NAME = 0x01,
> > +	OPAL_TABLE_COMMON = 0x02,
> > +	OPAL_TABLE_TEMPLATE = 0x03,
> > +	OPAL_TABLE_KIND = 0x04,
> > +	OPAL_TABLE_COLUMN = 0x05,
> > +	OPAL_TABLE_COLUMNS = 0x06,
> > +	OPAL_TABLE_ROWS = 0x07,
> > +	OPAL_TABLE_ROWS_FREE = 0x08,
> > +	OPAL_TABLE_ROW_BYTES = 0x09,
> > +	OPAL_TABLE_LASTID = 0x0A,
> > +	OPAL_TABLE_MIN = 0x0B,
> > +	OPAL_TABLE_MAX = 0x0C,
> > +
> >  	/* authority table */
> >  	OPAL_PIN = 0x03,
> >  	/* locking tokens */
> > diff --git a/block/sed-opal.c b/block/sed-opal.c
> > index 2459ac4d523b..3493bb979978 100644
> > --- a/block/sed-opal.c
> > +++ b/block/sed-opal.c
> > @@ -139,6 +139,8 @@ static const u8 opaluid[][OPAL_UID_LENGTH] = {
> >
> >  	/* tables */
> >
> > +	[OPAL_TABLE_TABLE]
> > +		{ 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01 },
> >  	[OPAL_LOCKINGRANGE_GLOBAL] =
> >  		{ 0x00, 0x00, 0x08, 0x02, 0x00, 0x00, 0x00, 0x01 },
> >  	[OPAL_LOCKINGRANGE_ACE_RDLOCKED] =
> > @@ -1120,6 +1122,29 @@ static int generic_get_column(struct opal_dev *dev, const u8 *table,
> >  	return finalize_and_send(dev, parse_and_check_status);
> >  }
> >
> > +/*
> > + * see TCG SAS 5.3.2.3 for a description of the available columns
> > + *
> > + * the result is provided in dev->resp->tok[4]
> > + */
> > +static int generic_get_table_info(struct opal_dev *dev, enum opal_uid table,
> > +				  u64 column)
> > +{
> > +	u8 uid[OPAL_UID_LENGTH];
> > +	const unsigned int half = OPAL_UID_LENGTH/2;
> > +
> > +	/* sed-opal UIDs can be split in two halves:
> > +	 *  first:  actual table index
> > +	 *  second: relative index in the table
> > +	 * so we have to get the first half of the OPAL_TABLE_TABLE and use the
> > +	 * first part of the target table as relative index into that table
> > +	 */
> > +	memcpy(uid, opaluid[OPAL_TABLE_TABLE], half);
> > +	memcpy(uid+half, opaluid[table], half);
> > +
> > +	return generic_get_column(dev, uid, column);
> > +}
> > +
> >  static int gen_key(struct opal_dev *dev, void *data)
> >  {
> >  	u8 uid[OPAL_UID_LENGTH];
> > @@ -1535,6 +1560,20 @@ static int write_shadow_mbr(struct opal_dev *dev, void *data)
> >  	u64 len;
> >  	int err = 0;
> >
> > +	/* do we fit in the available shadow mbr space? */
> > +	err = generic_get_table_info(dev, OPAL_MBR, OPAL_TABLE_ROWS);
> Wouldn't you need to multiply this by result from OPAL_TABLE_ROWBYTES?
> What does ROWBYTES return for you?

Hi Jon,

reading the spec[1], I think it defines the MBR table to be a "byte table" 
(see 5.7.2.6 MBR (Byte Table)). For byte tables, it says (see 3.2.5.1 
Kinds of Tables) "A byte table has one unnamed column of type bytes_1." I 
think this implies that each row is 1 byte and so number of rows = size of 
table in rows.

When I actually try to get OPAL_TABLE_ROWS abd OPAL_TABLE_ROWBYTES of the 
MBR table from a Samsung 840 EVO, I get:
* OPAL_TABLE_ROWS 134217728 which is 128 MiB
* OPAL_TABLE_ROWBYTES 0

I'm not sure if I'm doing something wrong here. I just added:

	err = generic_get_table_info(dev, OPAL_MBR, OPAL_TABLE_ROW_BYTES);
	if (err) {
		pr_debug("MBR: could not get shadow row bytes size\n");
		return err;
	}

	row_bytes = response_get_u64(&dev->parsed, 4);

Best regards,
David

[1] https://trustedcomputinggroup.org/wp-content/uploads/TCG_Storage_Architecture_Core_Spec_v2.01_r1.00.pdf