Commit c1f480b2 authored by Luca Boccassi's avatar Luca Boccassi Committed by Jens Axboe
Browse files

sed-opal: allow using IOC_OPAL_SAVE for locking too 



Usually when closing a crypto device (eg: dm-crypt with LUKS) the
volume key is not required, as it requires root privileges anyway, and
root can deny access to a disk in many ways regardless. Requiring the
volume key to lock the device is a peculiarity of the OPAL
specification.

Given we might already have saved the key if the user requested it via
the 'IOC_OPAL_SAVE' ioctl, we can use that key to lock the device if no
key was provided here and the locking range matches, and the user sets
the appropriate flag with 'IOC_OPAL_SAVE'. This allows integrating OPAL
with tools and libraries that are used to the common behaviour and do
not ask for the volume key when closing a device.

Callers can always pass a non-zero key and it will be used regardless,
as before.

Suggested-by: default avatarŠtěpán Horáček <stepan.horacek@gmail.com>
Signed-off-by: default avatarLuca Boccassi <bluca@debian.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarChristian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20221206092913.4625-1-luca.boccassi@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 37754595

block/sed-opal.c

+39 −0
Original line number Diff line number Diff line
@@ -2437,6 +2437,44 @@ static int __opal_set_mbr_done(struct opal_dev *dev, struct opal_key *key) 
	return execute_steps(dev, mbrdone_step, ARRAY_SIZE(mbrdone_step));

}



static void opal_lock_check_for_saved_key(struct opal_dev *dev,

			    struct opal_lock_unlock *lk_unlk)

{

	struct opal_suspend_data *iter;



	if (lk_unlk->l_state != OPAL_LK ||

			lk_unlk->session.opal_key.key_len > 0)

		return;



	/*

	 * Usually when closing a crypto device (eg: dm-crypt with LUKS) the

	 * volume key is not required, as it requires root privileges anyway,

	 * and root can deny access to a disk in many ways regardless.

	 * Requiring the volume key to lock the device is a peculiarity of the

	 * OPAL specification. Given we might already have saved the key if

	 * the user requested it via the 'IOC_OPAL_SAVE' ioctl, we can use

	 * that key to lock the device if no key was provided here, the

	 * locking range matches and the appropriate flag was passed with

	 * 'IOC_OPAL_SAVE'.

	 * This allows integrating OPAL with tools and libraries that are used

	 * to the common behaviour and do not ask for the volume key when

	 * closing a device.

	 */

	setup_opal_dev(dev);

	list_for_each_entry(iter, &dev->unlk_lst, node) {

		if ((iter->unlk.flags & OPAL_SAVE_FOR_LOCK) &&

				iter->lr == lk_unlk->session.opal_key.lr &&

				iter->unlk.session.opal_key.key_len > 0) {

			lk_unlk->session.opal_key.key_len =

				iter->unlk.session.opal_key.key_len;

			memcpy(lk_unlk->session.opal_key.key,

				iter->unlk.session.opal_key.key,

				iter->unlk.session.opal_key.key_len);

			break;

		}

	}

}



static int opal_lock_unlock(struct opal_dev *dev,

			    struct opal_lock_unlock *lk_unlk)

{
@@ -2446,6 +2484,7 @@ static int opal_lock_unlock(struct opal_dev *dev, 
		return -EINVAL;



	mutex_lock(&dev->dev_lock);

	opal_lock_check_for_saved_key(dev, lk_unlk);

	ret = __opal_lock_unlock(dev, lk_unlk);

	mutex_unlock(&dev->dev_lock);

include/uapi/linux/sed-opal.h

+7 −1
Original line number Diff line number Diff line
@@ -44,6 +44,11 @@ enum opal_lock_state { 
	OPAL_LK = 0x04, /* 0100 */

};



enum opal_lock_flags {

	/* IOC_OPAL_SAVE will also store the provided key for locking */

	OPAL_SAVE_FOR_LOCK = 0x01,

};



struct opal_key {

	__u8 lr;

	__u8 key_len;
@@ -76,7 +81,8 @@ struct opal_user_lr_setup { 
struct opal_lock_unlock {

	struct opal_session_info session;

	__u32 l_state;

	__u8 __align[4];

	__u16 flags;

	__u8 __align[2];

};



struct opal_new_pw {