block: sed-opal: Add ioctl to return device status

Provide a mechanism to retrieve basic status information about
the device, including the "supported" flag indicating whether
SED-OPAL is supported. The information returned is from the various
feature descriptors received during the discovery0 step, and so
this ioctl does nothing more than perform the discovery0 step
and then save the information received. See "struct opal_status"
and OPAL_FL_* bits for the status information currently returned.

This is necessary to be able to check whether a device is OPAL
enabled, set up, locked or unlocked from userspace programs
like systemd-cryptsetup and libcryptsetup. Right now we just
have to assume the user 'knows' or blindly attempt setup/lock/unlock
operations.

Signed-off-by: Douglas Miller <[e-mail]>
Tested-by: Luca Boccassi <[e-mail]>
Reviewed-by: Scott Bauer <[e-mail]>
Acked-by: Christian Brauner (Microsoft) <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jens Axboe <[e-mail]>

block/opal_proto.h

···
 #define FIRST_TPER_SESSION_NUM	4096
 
 #define TPER_SYNC_SUPPORTED 0x01
+/* FC_LOCKING features */
+#define LOCKING_SUPPORTED_MASK 0x01
+#define LOCKING_ENABLED_MASK 0x02
+#define LOCKED_MASK 0x04
 #define MBR_ENABLED_MASK 0x10
+#define MBR_DONE_MASK 0x20
 
 #define TINY_ATOM_DATA_MASK 0x3F
 #define TINY_ATOM_SIGNED 0x40

block/sed-opal.c

···
 };
 
 struct opal_dev {
-	bool supported;
-	bool mbr_enabled;
+	u32 flags;
 
 	void *data;
 	sec_send_recv *send_recv;
···
 	return true;
 }
 
+static bool check_lcksuppt(const void *data)
+{
+	const struct d0_locking_features *lfeat = data;
+	u8 sup_feat = lfeat->supported_features;
+
+	return !!(sup_feat & LOCKING_SUPPORTED_MASK);
+}
+
+static bool check_lckenabled(const void *data)
+{
+	const struct d0_locking_features *lfeat = data;
+	u8 sup_feat = lfeat->supported_features;
+
+	return !!(sup_feat & LOCKING_ENABLED_MASK);
+}
+
+static bool check_locked(const void *data)
+{
+	const struct d0_locking_features *lfeat = data;
+	u8 sup_feat = lfeat->supported_features;
+
+	return !!(sup_feat & LOCKED_MASK);
+}
+
 static bool check_mbrenabled(const void *data)
 {
 	const struct d0_locking_features *lfeat = data;
 	u8 sup_feat = lfeat->supported_features;
 
 	return !!(sup_feat & MBR_ENABLED_MASK);
+}
+
+static bool check_mbrdone(const void *data)
+{
+	const struct d0_locking_features *lfeat = data;
+	u8 sup_feat = lfeat->supported_features;
+
+	return !!(sup_feat & MBR_DONE_MASK);
 }
 
 static bool check_sum(const void *data)
···
 	u32 hlen = be32_to_cpu(hdr->length);
 
 	print_buffer(dev->resp, hlen);
-	dev->mbr_enabled = false;
+	dev->flags &= OPAL_FL_SUPPORTED;
 
 	if (hlen > IO_BUFFER_LENGTH - sizeof(*hdr)) {
 		pr_debug("Discovery length overflows buffer (%zu+%u)/%u\n",
···
 			check_geometry(dev, body);
 			break;
 		case FC_LOCKING:
-			dev->mbr_enabled = check_mbrenabled(body->features);
+			if (check_lcksuppt(body->features))
+				dev->flags |= OPAL_FL_LOCKING_SUPPORTED;
+			if (check_lckenabled(body->features))
+				dev->flags |= OPAL_FL_LOCKING_ENABLED;
+			if (check_locked(body->features))
+				dev->flags |= OPAL_FL_LOCKED;
+			if (check_mbrenabled(body->features))
+				dev->flags |= OPAL_FL_MBR_ENABLED;
+			if (check_mbrdone(body->features))
+				dev->flags |= OPAL_FL_MBR_DONE;
 			break;
 		case FC_ENTERPRISE:
 		case FC_DATASTORE:
···
 	mutex_lock(&dev->dev_lock);
 	setup_opal_dev(dev);
 	ret = opal_discovery0_step(dev);
-	dev->supported = !ret;
+	if (!ret)
+		dev->flags |= OPAL_FL_SUPPORTED;
 	mutex_unlock(&dev->dev_lock);
 
 	return ret;
···
 
 	INIT_LIST_HEAD(&dev->unlk_lst);
 	mutex_init(&dev->dev_lock);
+	dev->flags = 0;
 	dev->data = data;
 	dev->send_recv = send_recv;
 	if (check_opal_support(dev) != 0) {
···
 	if (!dev)
 		return false;
 
-	if (!dev->supported)
+	if (!(dev->flags & OPAL_FL_SUPPORTED))
 		return false;
 
 	mutex_lock(&dev->dev_lock);
···
 			was_failure = true;
 		}
 
-		if (dev->mbr_enabled) {
+		if (dev->flags & OPAL_FL_MBR_ENABLED) {
 			ret = __opal_set_mbr_done(dev, &suspend->unlk.session.opal_key);
 			if (ret)
 				pr_debug("Failed to set MBR Done in S3 resume\n");
···
 	return ret;
 }
 
+static int opal_get_status(struct opal_dev *dev, void __user *data)
+{
+	struct opal_status sts = {0};
+
+	/*
+	 * check_opal_support() error is not fatal,
+	 * !dev->supported is a valid condition
+	 */
+	if (!check_opal_support(dev))
+		sts.flags = dev->flags;
+	if (copy_to_user(data, &sts, sizeof(sts))) {
+		pr_debug("Error copying status to userspace\n");
+		return -EFAULT;
+	}
+	return 0;
+}
+
 int sed_ioctl(struct opal_dev *dev, unsigned int cmd, void __user *arg)
 {
 	void *p;
···
 		return -EACCES;
 	if (!dev)
 		return -ENOTSUPP;
-	if (!dev->supported)
+	if (!(dev->flags & OPAL_FL_SUPPORTED))
 		return -ENOTSUPP;
 
-	p = memdup_user(arg, _IOC_SIZE(cmd));
-	if (IS_ERR(p))
-		return PTR_ERR(p);
+	if (cmd & IOC_IN) {
+		p = memdup_user(arg, _IOC_SIZE(cmd));
+		if (IS_ERR(p))
+			return PTR_ERR(p);
+	}
 
 	switch (cmd) {
 	case IOC_OPAL_SAVE:
···
 	case IOC_OPAL_GENERIC_TABLE_RW:
 		ret = opal_generic_read_write_table(dev, p);
 		break;
+	case IOC_OPAL_GET_STATUS:
+		ret = opal_get_status(dev, arg);
+		break;
 	default:
 		break;
 	}
 
-	kfree(p);
+	if (cmd & IOC_IN)
+		kfree(p);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(sed_ioctl);

include/linux/sed-opal.h

···
 	case IOC_OPAL_MBR_DONE:
 	case IOC_OPAL_WRITE_SHADOW_MBR:
 	case IOC_OPAL_GENERIC_TABLE_RW:
+	case IOC_OPAL_GET_STATUS:
 		return true;
 	}
 	return false;

include/uapi/linux/sed-opal.h

···
 	__u64 priv;
 };
 
+#define OPAL_FL_SUPPORTED		0x00000001
+#define OPAL_FL_LOCKING_SUPPORTED	0x00000002
+#define OPAL_FL_LOCKING_ENABLED		0x00000004
+#define OPAL_FL_LOCKED			0x00000008
+#define OPAL_FL_MBR_ENABLED		0x00000010
+#define OPAL_FL_MBR_DONE		0x00000020
+
+struct opal_status {
+	__u32 flags;
+	__u32 reserved;
+};
+
 #define IOC_OPAL_SAVE		    _IOW('p', 220, struct opal_lock_unlock)
 #define IOC_OPAL_LOCK_UNLOCK	    _IOW('p', 221, struct opal_lock_unlock)
 #define IOC_OPAL_TAKE_OWNERSHIP	    _IOW('p', 222, struct opal_key)
···
 #define IOC_OPAL_MBR_DONE           _IOW('p', 233, struct opal_mbr_done)
 #define IOC_OPAL_WRITE_SHADOW_MBR   _IOW('p', 234, struct opal_shadow_mbr)
 #define IOC_OPAL_GENERIC_TABLE_RW   _IOW('p', 235, struct opal_read_write_table)
+#define IOC_OPAL_GET_STATUS         _IOR('p', 236, struct opal_status)
 
 #endif /* _UAPI_SED_OPAL_H */