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

["Derrick, Jonathan" <jonathan.derrick@intel.com>]

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On Sun, 2019-02-10 at 21:05 +0100, David Kozub wrote:
> 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@studium.uni-erlangen.de>
> > > 
> > > 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@studium.uni-erl
> > > angen.de>
> > > Reviewed-by: Scott Bauer <sbauer@plzdonthack.me>
> > > ---
> > >  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

I also see ROWS=0x8000000 and ROWBYTES=0 on an Intel drive, so my
interpretation of rowbytes was probably incorrect.

Reviewed-by: Jon Derrick <jonathan.derrick@intel.com>

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