block: sed-opal: check size of shadow mbr

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>
Signed-off-by: David Kozub <zub@linux.fjfi.cvut.cz>
Reviewed-by: Scott Bauer <sbauer@plzdonthack.me>
Reviewed-by: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/opal_proto.h

@@ -98,6 +98,7 @@ 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,
@@ -152,6 +153,21 @@ 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 */

block/sed-opal.c

@@ -130,6 +130,8 @@ 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] =
@@ -1131,6 +1133,29 @@ 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];
@@ -1557,6 +1582,20 @@ 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);
+	if (err) {
+		pr_debug("MBR: could not get shadow size\n");
+		return err;
+	}
+
+	len = response_get_u64(&dev->parsed, 4);
+	if (shadow->size > len || shadow->offset > len - shadow->size) {
+		pr_debug("MBR: does not fit in shadow (%llu vs. %llu)\n",
+			 shadow->offset + shadow->size, len);
+		return -ENOSPC;
+	}
+
 	/* do the actual transmission(s) */
 	src = (u8 __user *)(uintptr_t)shadow->data;
 	while (off < shadow->size) {