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Message-ID: <20250422214211.242382-3-ebiggers@kernel.org>
Date: Tue, 22 Apr 2025 14:42:11 -0700
From: Eric Biggers <ebiggers@...nel.org>
To: dm-devel@...ts.linux.dev,
Alasdair Kergon <agk@...hat.com>,
Mike Snitzer <snitzer@...nel.org>,
Mikulas Patocka <mpatocka@...hat.com>
Cc: linux-block@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-fscrypt@...r.kernel.org,
Bartosz Golaszewski <brgl@...ev.pl>,
Gaurav Kashyap <quic_gaurkash@...cinc.com>
Subject: [PATCH 2/2] dm: pass through operations on wrapped inline crypto keys
From: Eric Biggers <ebiggers@...gle.com>
Make the device-mapper layer pass through the derive_sw_secret,
import_key, generate_key, and prepare_key blk-crypto operations when all
underlying devices support hardware-wrapped inline crypto keys and are
passing through inline crypto support.
Commit ebc4176551cd ("blk-crypto: add basic hardware-wrapped key
support") already made BLK_CRYPTO_KEY_TYPE_HW_WRAPPED be passed through
in the same way that the other crypto capabilities are. But the wrapped
key support also includes additional operations in blk_crypto_ll_ops,
and the dm layer needs to implement those to pass them through.
derive_sw_secret is needed by fscrypt, while the other operations are
needed for the new blk-crypto ioctls to work on device-mapper devices
and not just the raw partitions.
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
---
I've tried to share code between the different operations, but it was a
little difficult since currently dm device iteration is callback-based.
Hopefully the current patch is okay, but we can also duplicate the
iteration code for each operation if that's preferred.
drivers/md/dm-table.c | 175 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 175 insertions(+)
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 35100a435c88b..9922607a25ddc 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1188,10 +1188,178 @@ static int dm_keyslot_evict(struct blk_crypto_profile *profile,
dm_put_live_table(md, srcu_idx);
return 0;
}
+enum dm_wrappedkey_op {
+ DERIVE_SW_SECRET,
+ IMPORT_KEY,
+ GENERATE_KEY,
+ PREPARE_KEY,
+};
+
+struct dm_wrappedkey_op_args {
+ enum dm_wrappedkey_op op;
+ int err;
+ union {
+ struct {
+ const u8 *eph_key;
+ size_t eph_key_size;
+ u8 *sw_secret;
+ } derive_sw_secret;
+ struct {
+ const u8 *raw_key;
+ size_t raw_key_size;
+ u8 *lt_key;
+ } import_key;
+ struct {
+ u8 *lt_key;
+ } generate_key;
+ struct {
+ const u8 *lt_key;
+ size_t lt_key_size;
+ u8 *eph_key;
+ } prepare_key;
+ };
+};
+
+static int dm_wrappedkey_op_callback(struct dm_target *ti, struct dm_dev *dev,
+ sector_t start, sector_t len, void *data)
+{
+ struct dm_wrappedkey_op_args *args = data;
+ struct block_device *bdev = dev->bdev;
+ struct blk_crypto_profile *profile =
+ bdev_get_queue(bdev)->crypto_profile;
+ int err = -EOPNOTSUPP;
+
+ if (!args->err)
+ return 0;
+
+ switch (args->op) {
+ case DERIVE_SW_SECRET:
+ err = blk_crypto_derive_sw_secret(
+ bdev,
+ args->derive_sw_secret.eph_key,
+ args->derive_sw_secret.eph_key_size,
+ args->derive_sw_secret.sw_secret);
+ break;
+ case IMPORT_KEY:
+ err = blk_crypto_import_key(profile,
+ args->import_key.raw_key,
+ args->import_key.raw_key_size,
+ args->import_key.lt_key);
+ break;
+ case GENERATE_KEY:
+ err = blk_crypto_generate_key(profile,
+ args->generate_key.lt_key);
+ break;
+ case PREPARE_KEY:
+ err = blk_crypto_prepare_key(profile,
+ args->prepare_key.lt_key,
+ args->prepare_key.lt_key_size,
+ args->prepare_key.eph_key);
+ break;
+ }
+ args->err = err;
+
+ /* Try another device in case this fails. */
+ return 0;
+}
+
+static int dm_exec_wrappedkey_op(struct blk_crypto_profile *profile,
+ struct dm_wrappedkey_op_args *args)
+{
+ struct mapped_device *md =
+ container_of(profile, struct dm_crypto_profile, profile)->md;
+ struct dm_target *ti;
+ struct dm_table *t;
+ int srcu_idx;
+ int i;
+
+ t = dm_get_live_table(md, &srcu_idx);
+ if (!t)
+ return -EOPNOTSUPP;
+
+ /*
+ * blk-crypto currently has no support for multiple incompatible
+ * implementations of wrapped inline crypto keys on a single system.
+ * It was already checked earlier that support for wrapped keys was
+ * declared on all underlying devices. Thus, all the underlying devices
+ * should support all wrapped key operations and they should behave
+ * identically, i.e. work with the same keys. So, just executing the
+ * operation on the first device on which it works suffices for now.
+ */
+ args->err = -EOPNOTSUPP;
+ for (i = 0; i < t->num_targets; i++) {
+ ti = dm_table_get_target(t, i);
+ if (!ti->type->iterate_devices)
+ continue;
+ ti->type->iterate_devices(ti, dm_wrappedkey_op_callback, args);
+ if (!args->err)
+ break;
+ }
+ dm_put_live_table(md, srcu_idx);
+ return args->err;
+}
+
+static int dm_derive_sw_secret(struct blk_crypto_profile *profile,
+ const u8 *eph_key, size_t eph_key_size,
+ u8 sw_secret[BLK_CRYPTO_SW_SECRET_SIZE])
+{
+ struct dm_wrappedkey_op_args args = {
+ .op = DERIVE_SW_SECRET,
+ .derive_sw_secret = {
+ .eph_key = eph_key,
+ .eph_key_size = eph_key_size,
+ .sw_secret = sw_secret,
+ },
+ };
+ return dm_exec_wrappedkey_op(profile, &args);
+}
+
+static int dm_import_key(struct blk_crypto_profile *profile,
+ const u8 *raw_key, size_t raw_key_size,
+ u8 lt_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE])
+{
+ struct dm_wrappedkey_op_args args = {
+ .op = IMPORT_KEY,
+ .import_key = {
+ .raw_key = raw_key,
+ .raw_key_size = raw_key_size,
+ .lt_key = lt_key,
+ },
+ };
+ return dm_exec_wrappedkey_op(profile, &args);
+}
+
+static int dm_generate_key(struct blk_crypto_profile *profile,
+ u8 lt_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE])
+{
+ struct dm_wrappedkey_op_args args = {
+ .op = GENERATE_KEY,
+ .generate_key = {
+ .lt_key = lt_key,
+ },
+ };
+ return dm_exec_wrappedkey_op(profile, &args);
+}
+
+static int dm_prepare_key(struct blk_crypto_profile *profile,
+ const u8 *lt_key, size_t lt_key_size,
+ u8 eph_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE])
+{
+ struct dm_wrappedkey_op_args args = {
+ .op = PREPARE_KEY,
+ .prepare_key = {
+ .lt_key = lt_key,
+ .lt_key_size = lt_key_size,
+ .eph_key = eph_key,
+ },
+ };
+ return dm_exec_wrappedkey_op(profile, &args);
+}
+
static int
device_intersect_crypto_capabilities(struct dm_target *ti, struct dm_dev *dev,
sector_t start, sector_t len, void *data)
{
struct blk_crypto_profile *parent = data;
@@ -1262,10 +1430,17 @@ static int dm_table_construct_crypto_profile(struct dm_table *t)
ti->type->iterate_devices(ti,
device_intersect_crypto_capabilities,
profile);
}
+ if (profile->key_types_supported & BLK_CRYPTO_KEY_TYPE_HW_WRAPPED) {
+ profile->ll_ops.derive_sw_secret = dm_derive_sw_secret;
+ profile->ll_ops.import_key = dm_import_key;
+ profile->ll_ops.generate_key = dm_generate_key;
+ profile->ll_ops.prepare_key = dm_prepare_key;
+ }
+
if (t->md->queue &&
!blk_crypto_has_capabilities(profile,
t->md->queue->crypto_profile)) {
DMERR("Inline encryption capabilities of new DM table were more restrictive than the old table's. This is not supported!");
dm_destroy_crypto_profile(profile);
--
2.49.0
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