Fix clone handling with encryption roots

Currently, spa_keystore_change_key_sync_impl() does not recurse
into clones when updating encryption roots for either a call to
'zfs promote' or 'zfs change-key'. This can cause children of
these clones to end up in a state where they point to the wrong
dataset as the encryption root. It can also trigger ASSERTs in
some cases where the code checks reference counts on wrapping
keys. This patch fixes this issue by ensuring that this function
properly recurses into clones during processing.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alek Pinchuk <apinchuk@datto.com>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes #9267 
Closes #9294

module/zfs/dsl_crypt.c

@@ -1418,10 +1418,17 @@ error:
 	return (ret);
 }
 
-
+/*
+ * This function deals with the intricacies of updating wrapping
+ * key references and encryption roots recursively in the event
+ * of a call to 'zfs change-key' or 'zfs promote'. The 'skip'
+ * parameter should always be set to B_FALSE when called
+ * externally.
+ */
 static void
 spa_keystore_change_key_sync_impl(uint64_t rddobj, uint64_t ddobj,
-    uint64_t new_rddobj, dsl_wrapping_key_t *wkey, dmu_tx_t *tx)
+    uint64_t new_rddobj, dsl_wrapping_key_t *wkey, boolean_t skip,
+    dmu_tx_t *tx)
 {
 	zap_cursor_t *zc;
 	zap_attribute_t *za;
@@ -1435,7 +1442,7 @@ spa_keystore_change_key_sync_impl(uint64_t rddobj, uint64_t ddobj,
 	/* hold the dd */
 	VERIFY0(dsl_dir_hold_obj(dp, ddobj, NULL, FTAG, &dd));
 
-	/* ignore hidden dsl dirs */
+	/* ignore special dsl dirs */
 	if (dd->dd_myname[0] == '$' || dd->dd_myname[0] == '%') {
 		dsl_dir_rele(dd, FTAG);
 		return;
@@ -1446,7 +1453,7 @@ spa_keystore_change_key_sync_impl(uint64_t rddobj, uint64_t ddobj,
 	 * or if this dd is a clone.
 	 */
 	VERIFY0(dsl_dir_get_encryption_root_ddobj(dd, &curr_rddobj));
-	if (curr_rddobj != rddobj || dsl_dir_is_clone(dd)) {
+	if (!skip && (curr_rddobj != rddobj || dsl_dir_is_clone(dd))) {
 		dsl_dir_rele(dd, FTAG);
 		return;
 	}
@@ -1454,11 +1461,14 @@ spa_keystore_change_key_sync_impl(uint64_t rddobj, uint64_t ddobj,
 	/*
 	 * If we don't have a wrapping key just update the dck to reflect the
 	 * new encryption root. Otherwise rewrap the entire dck and re-sync it
-	 * to disk.
+	 * to disk. If skip is set, we don't do any of this work.
 	 */
+	if (!skip) {
 		if (wkey == NULL) {
-		VERIFY0(zap_update(dp->dp_meta_objset, dd->dd_crypto_obj,
+			VERIFY0(zap_update(dp->dp_meta_objset,
-		    DSL_CRYPTO_KEY_ROOT_DDOBJ, 8, 1, &new_rddobj, tx));
+			    dd->dd_crypto_obj,
+			    DSL_CRYPTO_KEY_ROOT_DDOBJ, 8, 1,
+			    &new_rddobj, tx));
 		} else {
 			VERIFY0(spa_keystore_dsl_key_hold_dd(dp->dp_spa, dd,
 			    FTAG, &dck));
@@ -1468,6 +1478,7 @@ spa_keystore_change_key_sync_impl(uint64_t rddobj, uint64_t ddobj,
 			dsl_crypto_key_sync(dck, tx);
 			spa_keystore_dsl_key_rele(dp->dp_spa, dck, FTAG);
 		}
+	}
 
 	zc = kmem_alloc(sizeof (zap_cursor_t), KM_SLEEP);
 	za = kmem_alloc(sizeof (zap_attribute_t), KM_SLEEP);
@@ -1478,7 +1489,27 @@ spa_keystore_change_key_sync_impl(uint64_t rddobj, uint64_t ddobj,
 	    zap_cursor_retrieve(zc, za) == 0;
 	    zap_cursor_advance(zc)) {
 		spa_keystore_change_key_sync_impl(rddobj,
-		    za->za_first_integer, new_rddobj, wkey, tx);
+		    za->za_first_integer, new_rddobj, wkey, B_FALSE, tx);
+	}
+	zap_cursor_fini(zc);
+
+	/*
+	 * Recurse into all dsl dirs of clones. We utilize the skip parameter
+	 * here so that we don't attempt to process the clones directly. This
+	 * is because the clone and its origin share the same dck, which has
+	 * already been updated.
+	 */
+	for (zap_cursor_init(zc, dp->dp_meta_objset,
+	    dsl_dir_phys(dd)->dd_clones);
+	    zap_cursor_retrieve(zc, za) == 0;
+	    zap_cursor_advance(zc)) {
+		dsl_dataset_t *clone;
+
+		VERIFY0(dsl_dataset_hold_obj(dp, za->za_first_integer,
+		    FTAG, &clone));
+		spa_keystore_change_key_sync_impl(rddobj,
+		    clone->ds_dir->dd_object, new_rddobj, wkey, B_TRUE, tx);
+		dsl_dataset_rele(clone, FTAG);
 	}
 	zap_cursor_fini(zc);
 
@@ -1558,7 +1589,7 @@ spa_keystore_change_key_sync(void *arg, dmu_tx_t *tx)
 
 	/* recurse through all children and rewrap their keys */
 	spa_keystore_change_key_sync_impl(rddobj, ds->ds_dir->dd_object,
-	    new_rddobj, wkey, tx);
+	    new_rddobj, wkey, B_FALSE, tx);
 
 	/*
 	 * All references to the old wkey should be released now (if it
@@ -1736,7 +1767,7 @@ dsl_dataset_promote_crypt_sync(dsl_dir_t *target, dsl_dir_t *origin,
 
 	rw_enter(&dp->dp_spa->spa_keystore.sk_wkeys_lock, RW_WRITER);
 	spa_keystore_change_key_sync_impl(rddobj, origin->dd_object,
-	    target->dd_object, NULL, tx);
+	    target->dd_object, NULL, B_FALSE, tx);
 	rw_exit(&dp->dp_spa->spa_keystore.sk_wkeys_lock);
 
 	dsl_dataset_rele(targetds, FTAG);

tests/runfiles/linux.run

@@ -123,7 +123,7 @@ tags = ['functional', 'cli_root', 'zfs_bookmark']
 [tests/functional/cli_root/zfs_change-key]
 tests = ['zfs_change-key', 'zfs_change-key_child', 'zfs_change-key_format',
     'zfs_change-key_inherit', 'zfs_change-key_load', 'zfs_change-key_location',
-    'zfs_change-key_pbkdf2iters']
+    'zfs_change-key_pbkdf2iters', 'zfs_change-key_clones']
 tags = ['functional', 'cli_root', 'zfs_change-key']
 
 [tests/functional/cli_root/zfs_clone]

tests/zfs-tests/tests/functional/cli_root/zfs_change-key/Makefile.am

@@ -4,6 +4,7 @@ dist_pkgdata_SCRIPTS = \
 	cleanup.ksh \
 	zfs_change-key.ksh \
 	zfs_change-key_child.ksh \
+	zfs_change-key_clones.ksh \
 	zfs_change-key_inherit.ksh \
 	zfs_change-key_format.ksh \
 	zfs_change-key_load.ksh \

tests/zfs-tests/tests/functional/cli_root/zfs_change-key/zfs_change-key_clones.ksh

@@ -0,0 +1,80 @@
+#!/bin/ksh -p
+#
+# CDDL HEADER START
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright (c) 2017 Datto, Inc. All rights reserved.
+#
+
+. $STF_SUITE/include/libtest.shlib
+. $STF_SUITE/tests/functional/cli_root/zfs_load-key/zfs_load-key_common.kshlib
+
+#
+# DESCRIPTION:
+# 'zfs change-key' should correctly update encryption roots with clones.
+#
+# STRATEGY:
+# 1. Create an encrypted dataset
+# 2. Create an encryption root child of the first dataset
+# 3. Clone the child encryption root twice
+# 4. Add inheriting children to the encryption root and each of the clones
+# 5. Verify the encryption roots
+# 6. Have the child encryption root inherit from its parent
+# 7. Verify the encryption root for all datasets is now the parent dataset
+#
+
+verify_runnable "both"
+
+function cleanup
+{
+	datasetexists $TESTPOOL/$TESTFS1 && \
+		log_must zfs destroy -Rf $TESTPOOL/$TESTFS1
+}
+
+log_onexit cleanup
+
+log_assert "'zfs change-key' should correctly update encryption " \
+	"roots with clones"
+
+log_must eval "echo $PASSPHRASE1 | zfs create -o encryption=on" \
+	"-o keyformat=passphrase -o keylocation=prompt $TESTPOOL/$TESTFS1"
+log_must eval "echo $PASSPHRASE2 | zfs create -o encryption=on" \
+	"-o keyformat=passphrase -o keylocation=prompt $TESTPOOL/$TESTFS1/child"
+log_must zfs snapshot $TESTPOOL/$TESTFS1/child@1
+log_must zfs clone $TESTPOOL/$TESTFS1/child@1 $TESTPOOL/$TESTFS1/clone1
+log_must zfs clone $TESTPOOL/$TESTFS1/child@1 $TESTPOOL/$TESTFS1/clone2
+log_must zfs create $TESTPOOL/$TESTFS1/child/A
+log_must zfs create $TESTPOOL/$TESTFS1/clone1/B
+log_must zfs create $TESTPOOL/$TESTFS1/clone2/C
+
+log_must verify_encryption_root $TESTPOOL/$TESTFS1 $TESTPOOL/$TESTFS1
+log_must verify_encryption_root $TESTPOOL/$TESTFS1/child $TESTPOOL/$TESTFS1/child
+log_must verify_encryption_root $TESTPOOL/$TESTFS1/clone1 $TESTPOOL/$TESTFS1/child
+log_must verify_encryption_root $TESTPOOL/$TESTFS1/clone2 $TESTPOOL/$TESTFS1/child
+log_must verify_encryption_root $TESTPOOL/$TESTFS1/child/A $TESTPOOL/$TESTFS1/child
+log_must verify_encryption_root $TESTPOOL/$TESTFS1/clone1/B $TESTPOOL/$TESTFS1/child
+log_must verify_encryption_root $TESTPOOL/$TESTFS1/clone2/C $TESTPOOL/$TESTFS1/child
+
+log_must zfs change-key -i $TESTPOOL/$TESTFS1/child
+
+log_must verify_encryption_root $TESTPOOL/$TESTFS1 $TESTPOOL/$TESTFS1
+log_must verify_encryption_root $TESTPOOL/$TESTFS1/child $TESTPOOL/$TESTFS1
+log_must verify_encryption_root $TESTPOOL/$TESTFS1/clone1 $TESTPOOL/$TESTFS1
+log_must verify_encryption_root $TESTPOOL/$TESTFS1/clone2 $TESTPOOL/$TESTFS1
+log_must verify_encryption_root $TESTPOOL/$TESTFS1/child/A $TESTPOOL/$TESTFS1
+log_must verify_encryption_root $TESTPOOL/$TESTFS1/clone1/B $TESTPOOL/$TESTFS1
+log_must verify_encryption_root $TESTPOOL/$TESTFS1/clone2/C $TESTPOOL/$TESTFS1
+
+log_pass "'zfs change-key' correctly updates encryption roots with clones"

tests/zfs-tests/tests/functional/cli_root/zfs_promote/zfs_promote_encryptionroot.ksh

@@ -29,11 +29,12 @@
 # 1. Create an encrypted dataset
 # 2. Clone the encryption root
 # 3. Clone the clone
-# 4. Verify the encryption root of all three datasets is the origin
+# 4. Add children to each of these three datasets
+# 4. Verify the encryption root of all datasets is the origin
 # 5. Promote the clone of the clone
-# 6. Verify the encryption root of all three datasets is still the origin
+# 6. Verify the encryption root of all datasets is still the origin
-# 7. Promote the clone of the original encryption root
+# 7. Promote the dataset again, so it is now the encryption root
-# 8. Verify the encryption root of all three datasets is the promoted dataset
+# 8. Verify the encryption root of all datasets is the promoted dataset
 #
 
 verify_runnable "both"
@@ -62,19 +63,31 @@ log_must zfs snap $snaproot
 log_must zfs clone $snaproot $TESTPOOL/clone1
 log_must zfs snap $snapclone
 log_must zfs clone $snapclone $TESTPOOL/clone2
+log_must zfs create $TESTPOOL/$TESTFS1/child0
+log_must zfs create $TESTPOOL/clone1/child1
+log_must zfs create $TESTPOOL/clone2/child2
 
 log_must verify_encryption_root $TESTPOOL/$TESTFS1 $TESTPOOL/$TESTFS1
 log_must verify_encryption_root $TESTPOOL/clone1 $TESTPOOL/$TESTFS1
 log_must verify_encryption_root $TESTPOOL/clone2 $TESTPOOL/$TESTFS1
+log_must verify_encryption_root $TESTPOOL/$TESTFS1/child0 $TESTPOOL/$TESTFS1
+log_must verify_encryption_root $TESTPOOL/clone1/child1 $TESTPOOL/$TESTFS1
+log_must verify_encryption_root $TESTPOOL/clone2/child2 $TESTPOOL/$TESTFS1
 
 log_must zfs promote $TESTPOOL/clone2
 log_must verify_encryption_root $TESTPOOL/$TESTFS1 $TESTPOOL/$TESTFS1
 log_must verify_encryption_root $TESTPOOL/clone1 $TESTPOOL/$TESTFS1
 log_must verify_encryption_root $TESTPOOL/clone2 $TESTPOOL/$TESTFS1
+log_must verify_encryption_root $TESTPOOL/$TESTFS1/child0 $TESTPOOL/$TESTFS1
+log_must verify_encryption_root $TESTPOOL/clone1/child1 $TESTPOOL/$TESTFS1
+log_must verify_encryption_root $TESTPOOL/clone2/child2 $TESTPOOL/$TESTFS1
 
 log_must zfs promote $TESTPOOL/clone2
 log_must verify_encryption_root $TESTPOOL/$TESTFS1 $TESTPOOL/clone2
 log_must verify_encryption_root $TESTPOOL/clone1 $TESTPOOL/clone2
 log_must verify_encryption_root $TESTPOOL/clone2 $TESTPOOL/clone2
+log_must verify_encryption_root $TESTPOOL/$TESTFS1/child0 $TESTPOOL/clone2
+log_must verify_encryption_root $TESTPOOL/clone1/child1 $TESTPOOL/clone2
+log_must verify_encryption_root $TESTPOOL/clone2/child2 $TESTPOOL/clone2
 
 log_pass "ZFS promotes clones of an encryption root"