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

[David Kozub]

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

On Fri, 2019-02-01 at 21:50 +0100, David Kozub wrote:
From: Jonas Rabenstein <jonas.rabenst...@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.rabenst...@studium.uni-erlangen.de>
Reviewed-by: Scott Bauer <sba...@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