Allow block cloning across encrypted datasets

When two datasets share the same master encryption key, it is safe
to clone encrypted blocks. Currently only snapshots and clones
of a dataset share with it the same encryption key.

Added a test for:
- Clone from encrypted sibling to encrypted sibling with
  non encrypted parent
- Clone from encrypted parent to inherited encrypted child
- Clone from child to sibling with encrypted parent
- Clone from snapshot to the original datasets
- Clone from foreign snapshot to a foreign dataset
- Cloning from non-encrypted to encrypted datasets
- Cloning from encrypted to non-encrypted datasets

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Original-patch-by: Pawel Jakub Dawidek <pawel@dawidek.net>
Signed-off-by: Kay Pedersen <mail@mkwg.de>
Closes #15544

include/sys/dsl_crypt.h

@@ -206,6 +206,7 @@ void dsl_dataset_promote_crypt_sync(dsl_dir_t *target, dsl_dir_t *origin,
     dmu_tx_t *tx);
 int dmu_objset_create_crypt_check(dsl_dir_t *parentdd,
     dsl_crypto_params_t *dcp, boolean_t *will_encrypt);
+boolean_t dmu_objset_crypto_key_equal(objset_t *osa, objset_t *osb);
 void dsl_dataset_create_crypt_sync(uint64_t dsobj, dsl_dir_t *dd,
     struct dsl_dataset *origin, dsl_crypto_params_t *dcp, dmu_tx_t *tx);
 uint64_t dsl_crypto_key_create_sync(uint64_t crypt, dsl_wrapping_key_t *wkey,

man/man7/zpool-features.7

@@ -364,9 +364,12 @@ When this feature is enabled ZFS will use block cloning for operations like
 Block cloning allows to create multiple references to a single block.
 It is much faster than copying the data (as the actual data is neither read nor
 written) and takes no additional space.
-Blocks can be cloned across datasets under some conditions (like disabled
-encryption and equal
-.Nm recordsize ) .
+Blocks can be cloned across datasets under some conditions (like equal
+.Nm recordsize ,
+the same master encryption key, etc.).
+ZFS tries its best to clone across datasets including encrypted ones.
+This is limited for various (nontrivial) reasons depending on the OS
+and/or ZFS internals.
 .Pp
 This feature becomes
 .Sy active

module/zfs/brt.c

@@ -157,10 +157,8 @@
  * (copying the file content to the new dataset and removing the source file).
  * In that case Block Cloning will only be used briefly, because the BRT entries
  * will be removed when the source is removed.
- * Note: currently it is not possible to clone blocks between encrypted
- * datasets, even if those datasets use the same encryption key (this includes
- * snapshots of encrypted datasets). Cloning blocks between datasets that use
- * the same keys should be possible and should be implemented in the future.
+ * Block Cloning across encrypted datasets is supported as long as both
+ * datasets share the same master key (e.g. snapshots and clones)
  *
  * Block Cloning flow through ZFS layers.
  *

module/zfs/dsl_crypt.c

@@ -266,6 +266,40 @@ spa_crypto_key_compare(const void *a, const void *b)
 	return (0);
 }
 
+/*
+ * this compares a crypto key based on zk_guid. See comment on
+ * spa_crypto_key_compare for more information.
+ */
+boolean_t
+dmu_objset_crypto_key_equal(objset_t *osa, objset_t *osb)
+{
+	dsl_crypto_key_t *dcka = NULL;
+	dsl_crypto_key_t *dckb = NULL;
+	uint64_t obja, objb;
+	boolean_t equal;
+	spa_t *spa;
+
+	spa = dmu_objset_spa(osa);
+	if (spa != dmu_objset_spa(osb))
+		return (B_FALSE);
+	obja = dmu_objset_ds(osa)->ds_object;
+	objb = dmu_objset_ds(osb)->ds_object;
+
+	if (spa_keystore_lookup_key(spa, obja, FTAG, &dcka) != 0)
+		return (B_FALSE);
+	if (spa_keystore_lookup_key(spa, objb, FTAG, &dckb) != 0) {
+		spa_keystore_dsl_key_rele(spa, dcka, FTAG);
+		return (B_FALSE);
+	}
+
+	equal = (dcka->dck_key.zk_guid == dckb->dck_key.zk_guid);
+
+	spa_keystore_dsl_key_rele(spa, dcka, FTAG);
+	spa_keystore_dsl_key_rele(spa, dckb, FTAG);
+
+	return (equal);
+}
+
 static int
 spa_key_mapping_compare(const void *a, const void *b)
 {

module/zfs/zfs_vnops.c

@@ -47,6 +47,7 @@
 #include <sys/fs/zfs.h>
 #include <sys/dmu.h>
 #include <sys/dmu_objset.h>
+#include <sys/dsl_crypt.h>
 #include <sys/spa.h>
 #include <sys/txg.h>
 #include <sys/dbuf.h>
@@ -1097,6 +1098,16 @@ zfs_clone_range(znode_t *inzp, uint64_t *inoffp, znode_t *outzp,
 		return (SET_ERROR(EXDEV));
 	}
 
+	/*
+	 * Cloning across encrypted datasets is possible only if they
+	 * share the same master key.
+	 */
+	if (inos != outos && inos->os_encrypted &&
+	    !dmu_objset_crypto_key_equal(inos, outos)) {
+		zfs_exit_two(inzfsvfs, outzfsvfs, FTAG);
+		return (SET_ERROR(EXDEV));
+	}
+
 	error = zfs_verify_zp(inzp);
 	if (error == 0)
 		error = zfs_verify_zp(outzp);
@@ -1280,20 +1291,6 @@ zfs_clone_range(znode_t *inzp, uint64_t *inoffp, znode_t *outzp,
 			 */
 			break;
 		}
-		/*
-		 * Encrypted data is fine as long as it comes from the same
-		 * dataset.
-		 * TODO: We want to extend it in the future to allow cloning to
-		 * datasets with the same keys, like clones or to be able to
-		 * clone a file from a snapshot of an encrypted dataset into the
-		 * dataset itself.
-		 */
-		if (BP_IS_PROTECTED(&bps[0])) {
-			if (inzfsvfs != outzfsvfs) {
-				error = SET_ERROR(EXDEV);
-				break;
-			}
-		}
 
 		/*
 		 * Start a transaction.

tests/runfiles/linux.run

@@ -42,6 +42,7 @@ tests = ['block_cloning_copyfilerange', 'block_cloning_copyfilerange_partial',
     'block_cloning_disabled_copyfilerange', 'block_cloning_disabled_ficlone',
     'block_cloning_disabled_ficlonerange',
     'block_cloning_copyfilerange_cross_dataset',
+    'block_cloning_cross_enc_dataset',
     'block_cloning_copyfilerange_fallback_same_txg']
 tags = ['functional', 'block_cloning']
 

tests/test-runner/bin/zts-report.py.in

@@ -305,6 +305,8 @@ elif sys.platform.startswith('linux'):
             ['SKIP', cfr_cross_reason],
         'block_cloning/block_cloning_copyfilerange_fallback_same_txg':
             ['SKIP', cfr_cross_reason],
+        'block_cloning/block_cloning_cross_enc_dataset':
+            ['SKIP', cfr_cross_reason],
     })
 
 

tests/zfs-tests/tests/Makefile.am

@@ -451,6 +451,7 @@ nobase_dist_datadir_zfs_tests_tests_SCRIPTS += \
 	functional/block_cloning/block_cloning_ficlone.ksh \
 	functional/block_cloning/block_cloning_ficlonerange.ksh \
 	functional/block_cloning/block_cloning_ficlonerange_partial.ksh \
+	functional/block_cloning/block_cloning_cross_enc_dataset.ksh \
 	functional/bootfs/bootfs_001_pos.ksh \
 	functional/bootfs/bootfs_002_neg.ksh \
 	functional/bootfs/bootfs_003_pos.ksh \

tests/zfs-tests/tests/functional/block_cloning/block_cloning.kshlib

@@ -28,8 +28,8 @@
 
 function have_same_content
 {
-	typeset hash1=$(cat $1 | md5sum)
-	typeset hash2=$(cat $2 | md5sum)
+	typeset hash1=$(md5digest $1)
+	typeset hash2=$(md5digest $2)
 
 	log_must [ "$hash1" = "$hash2" ]
 }
@@ -44,10 +44,14 @@ function have_same_content
 #
 function get_same_blocks
 {
+    KEY=$5
+    if [ ${#KEY} -gt 0 ]; then
+        KEY="--key=$KEY"
+    fi
 	typeset zdbout=${TMPDIR:-$TEST_BASE_DIR}/zdbout.$$
-	zdb -vvvvv $1 -O $2 | \
+	zdb $KEY -vvvvv $1 -O $2 | \
 	    awk '/ L0 / { print l++ " " $3 " " $7 }' > $zdbout.a
-	zdb -vvvvv $3 -O $4 | \
+	zdb $KEY -vvvvv $3 -O $4 | \
 	    awk '/ L0 / { print l++ " " $3 " " $7 }' > $zdbout.b
 	echo $(sort $zdbout.a $zdbout.b | uniq -d | cut -f1 -d' ')
 }

tests/zfs-tests/tests/functional/block_cloning/block_cloning_cross_enc_dataset.ksh

@@ -0,0 +1,170 @@
+#!/bin/ksh -p
+#
+# CDDL HEADER START
+#
+# The contents of this file are subject to the terms of the
+# Common Development and Distribution License (the "License").
+# You may not use this file except in compliance with the License.
+#
+# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+# or https://opensource.org/licenses/CDDL-1.0.
+# See the License for the specific language governing permissions
+# and limitations under the License.
+#
+# When distributing Covered Code, include this CDDL HEADER in each
+# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+# If applicable, add the following below this CDDL HEADER, with the
+# fields enclosed by brackets "[]" replaced with your own identifying
+# information: Portions Copyright [yyyy] [name of copyright owner]
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright (c) 2023, Kay Pedersen <mail@mkwg.de>
+#
+
+. $STF_SUITE/include/libtest.shlib
+. $STF_SUITE/tests/functional/block_cloning/block_cloning.kshlib
+
+verify_runnable "global"
+
+if [[ $(linux_version) -lt $(linux_version "5.3") ]]; then
+  log_unsupported "copy_file_range can't copy cross-filesystem before Linux 5.3"
+fi
+
+claim="Block cloning across encrypted datasets."
+
+log_assert $claim
+
+DS1="$TESTPOOL/encrypted1"
+DS2="$TESTPOOL/encrypted2"
+DS1_NC="$TESTPOOL/notcrypted1"
+PASSPHRASE="top_secret"
+
+function prepare_enc
+{
+    log_must zpool create -o feature@block_cloning=enabled $TESTPOOL $DISKS
+    log_must eval "echo $PASSPHRASE | zfs create -o encryption=on" \
+	    "-o keyformat=passphrase -o keylocation=prompt $DS1"
+    log_must eval "echo $PASSPHRASE | zfs create -o encryption=on" \
+	    "-o keyformat=passphrase -o keylocation=prompt $DS2"
+    log_must zfs create $DS1/child1
+    log_must zfs create $DS1/child2
+    log_must zfs create $DS1_NC
+
+    log_note "Create test file"
+    # we must wait until the src file txg is written to the disk otherwise we
+    # will fallback to normal copy. See "dmu_read_l0_bps" in
+    # "zfs/module/zfs/dmu.c" and "zfs_clone_range" in
+    # "zfs/module/zfs/zfs_vnops.c"
+    log_must dd if=/dev/urandom of=/$DS1/file bs=128K count=4
+    log_must dd if=/dev/urandom of=/$DS1/child1/file bs=128K count=4
+    log_must dd if=/dev/urandom of=/$DS1_NC/file bs=128K count=4
+    log_must sync_pool $TESTPOOL
+}
+
+function cleanup_enc
+{
+	datasetexists $TESTPOOL && destroy_pool $TESTPOOL
+}
+
+function clone_and_check
+{
+    I_FILE="$1"
+    O_FILE=$2
+    I_DS=$3
+    O_DS=$4
+    SAME_BLOCKS=$5
+    # the CLONE option provides a choice between copy_file_range
+    # which should clone and a dd which is a copy no matter what
+    CLONE=$6
+    SNAPSHOT=$7
+    if [ ${#SNAPSHOT} -gt 0 ]; then
+        I_FILE=".zfs/snapshot/$SNAPSHOT/$1"
+    fi
+    if [ $CLONE ]; then
+        log_must clonefile -f "/$I_DS/$I_FILE" "/$O_DS/$O_FILE" 0 0 524288
+    else
+        log_must dd if="/$I_DS/$I_FILE" of="/$O_DS/$O_FILE" bs=128K
+    fi
+    log_must sync_pool $TESTPOOL
+
+    log_must have_same_content "/$I_DS/$I_FILE" "/$O_DS/$O_FILE"
+
+    if [ ${#SNAPSHOT} -gt 0 ]; then
+        I_DS="$I_DS@$SNAPSHOT"
+        I_FILE="$1"
+    fi
+    typeset blocks=$(get_same_blocks \
+      $I_DS $I_FILE $O_DS $O_FILE $PASSPHRASE)
+    log_must [ "$blocks" = "$SAME_BLOCKS" ]
+}
+
+log_onexit cleanup_enc
+
+prepare_enc
+
+log_note "Cloning entire file with copy_file_range across different enc" \
+    "roots, should fallback"
+# we are expecting no same block map.
+clone_and_check "file" "clone" $DS1 $DS2 "" true
+log_note "check if the file is still readable and the same after" \
+    "unmount and key unload, shouldn't fail"
+typeset hash1=$(md5digest "/$DS1/file")
+log_must zfs umount $DS1 && zfs unload-key $DS1
+typeset hash2=$(md5digest "/$DS2/clone")
+log_must [ "$hash1" = "$hash2" ]
+
+cleanup_enc
+prepare_enc
+
+log_note "Cloning entire file with copy_file_range across different child datasets"
+# clone shouldn't work because of deriving a new master key for the child
+# we are expecting no same block map.
+clone_and_check "file" "clone" $DS1 "$DS1/child1" "" true
+clone_and_check "file" "clone" "$DS1/child1" "$DS1/child2" "" true
+
+cleanup_enc
+prepare_enc
+
+log_note "Copying entire file with copy_file_range across same snapshot"
+log_must zfs snapshot -r $DS1@s1
+log_must sync_pool $TESTPOOL
+log_must rm -f "/$DS1/file"
+log_must sync_pool $TESTPOOL
+clone_and_check "file" "clone" "$DS1" "$DS1" "0 1 2 3" true "s1"
+
+cleanup_enc
+prepare_enc
+
+log_note "Copying entire file with copy_file_range across different snapshot"
+clone_and_check "file" "file" $DS1 $DS2 "" true
+log_must zfs snapshot -r $DS2@s1
+log_must sync_pool $TESTPOOL
+log_must rm -f "/$DS1/file" "/$DS2/file"
+log_must sync_pool $TESTPOOL
+clone_and_check "file" "clone" "$DS2" "$DS1" "" true "s1"
+typeset hash1=$(md5digest "/$DS1/.zfs/snapshot/s1/file")
+log_note "destroy the snapshot and check if the file is still readable and" \
+    "has the same content"
+log_must zfs destroy -r $DS2@s1
+log_must sync_pool $TESTPOOL
+typeset hash2=$(md5digest "/$DS1/file")
+log_must [ "$hash1" = "$hash2" ]
+
+cleanup_enc
+prepare_enc
+
+log_note "Copying with copy_file_range from non encrypted to encrypted"
+clone_and_check "file" "copy" $DS1_NC $DS1 "" true
+
+cleanup_enc
+prepare_enc
+
+log_note "Copying with copy_file_range from encrypted to non encrypted"
+clone_and_check "file" "copy" $DS1 $DS1_NC "" true
+
+log_must sync_pool $TESTPOOL
+
+log_pass $claim