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

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