linux-kernel - [PATCH v3 4/6] dm: Support key eviction from keyslot managers of underlying devices

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Message-Id: <20201229085524.2795331-5-satyat@google.com>
Date:   Tue, 29 Dec 2020 08:55:22 +0000
From:   Satya Tangirala <satyat@...gle.com>
To:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        dm-devel@...hat.com
Cc:     Jens Axboe <axboe@...nel.dk>, Alasdair Kergon <agk@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>,
        Eric Biggers <ebiggers@...gle.com>,
        Satya Tangirala <satyat@...gle.com>
Subject: [PATCH v3 4/6] dm: Support key eviction from keyslot managers of
 underlying devices

Now that device mapper supports inline encryption, add the ability to
evict keys from all underlying devices. When an upper layer requests
a key eviction, we simply iterate through all underlying devices
and evict that key from each device.

Co-developed-by: Eric Biggers <ebiggers@...gle.com>
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Signed-off-by: Satya Tangirala <satyat@...gle.com>
---
 block/blk-crypto.c |  1 +
 drivers/md/dm.c    | 53 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/block/blk-crypto.c b/block/blk-crypto.c
index 5da43f0973b4..c2be8f15006c 100644
--- a/block/blk-crypto.c
+++ b/block/blk-crypto.c
@@ -409,3 +409,4 @@ int blk_crypto_evict_key(struct request_queue *q,
 	 */
 	return blk_crypto_fallback_evict_key(key);
 }
+EXPORT_SYMBOL_GPL(blk_crypto_evict_key);
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 13b9c8e2e21b..b8844171d8e4 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1949,6 +1949,58 @@ struct dm_keyslot_manager {
 	struct mapped_device *md;
 };
 
+struct dm_keyslot_evict_args {
+	const struct blk_crypto_key *key;
+	int err;
+};
+
+static int dm_keyslot_evict_callback(struct dm_target *ti, struct dm_dev *dev,
+				     sector_t start, sector_t len, void *data)
+{
+	struct dm_keyslot_evict_args *args = data;
+	int err;
+
+	err = blk_crypto_evict_key(bdev_get_queue(dev->bdev), args->key);
+	if (!args->err)
+		args->err = err;
+	/* Always try to evict the key from all devices. */
+	return 0;
+}
+
+/*
+ * When an inline encryption key is evicted from a device-mapper device, evict
+ * it from all the underlying devices.
+ */
+static int dm_keyslot_evict(struct blk_keyslot_manager *ksm,
+			    const struct blk_crypto_key *key, unsigned int slot)
+{
+	struct dm_keyslot_manager *dksm = container_of(ksm,
+						       struct dm_keyslot_manager,
+						       ksm);
+	struct mapped_device *md = dksm->md;
+	struct dm_keyslot_evict_args args = { key };
+	struct dm_table *t;
+	int srcu_idx;
+	int i;
+	struct dm_target *ti;
+
+	t = dm_get_live_table(md, &srcu_idx);
+	if (!t)
+		return 0;
+	for (i = 0; i < dm_table_get_num_targets(t); i++) {
+		ti = dm_table_get_target(t, i);
+		if (!ti->type->iterate_devices)
+			continue;
+		ti->type->iterate_devices(ti, dm_keyslot_evict_callback, &args);
+	}
+	dm_put_live_table(md, srcu_idx);
+	return args.err;
+}
+
+static struct blk_ksm_ll_ops dm_ksm_ll_ops = {
+	.keyslot_evict = dm_keyslot_evict,
+};
+
 static int device_intersect_crypto_modes(struct dm_target *ti,
 					 struct dm_dev *dev, sector_t start,
 					 sector_t len, void *data)
@@ -1998,6 +2050,7 @@ dm_construct_keyslot_manager(struct mapped_device *md, struct dm_table *t)
 
 	ksm = &dksm->ksm;
 	blk_ksm_init_passthrough(ksm);
+	ksm->ksm_ll_ops = dm_ksm_ll_ops;
 	ksm->max_dun_bytes_supported = UINT_MAX;
 	memset(ksm->crypto_modes_supported, 0xFF,
 	       sizeof(ksm->crypto_modes_supported));
-- 
2.29.2.729.g45daf8777d-goog