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

Satya Tangirala
2020-12-29T08:57:12Z

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@google.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Satya Tangirala <satyat@google.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