Detect and prevent mixed raw and non-raw sends

Currently, there is an issue in the raw receive code where
raw receives are allowed to happen on top of previously
non-raw received datasets. This is a problem because the
source-side dataset doesn't know about how the blocks on
the destination were encrypted. As a result, any MAC in
the objset's checksum-of-MACs tree that is a parent of both
blocks encrypted on the source and blocks encrypted by the
destination will be incorrect. This will result in
authentication errors when we decrypt the dataset.

This patch fixes this issue by adding a new check to the
raw receive code. The code now maintains an "IVset guid",
which acts as an identifier for the set of IVs used to
encrypt a given snapshot. When a snapshot is raw received,
the destination snapshot will take this value from the
DRR_BEGIN payload. Non-raw receives and normal "zfs snap"
operations will cause ZFS to generate a new IVset guid.
When a raw incremental stream is received, ZFS will check
that the "from" IVset guid in the stream matches that of
the "from" destination snapshot. If they do not match, the
code will error out the receive, preventing the problem.

Signed-off-by: Tom Caputi <[email protected]>

include/sys/dmu_recv.h

@@ -51,7 +51,9 @@ typedef struct dmu_recv_cookie {
 	struct avl_tree *drc_guid_to_ds_map;
 	nvlist_t *drc_keynvl;
 	zio_cksum_t drc_cksum;
+	uint64_t drc_fromsnapobj;
 	uint64_t drc_newsnapobj;
+	uint64_t drc_ivset_guid;
 	void *drc_owner;
 	cred_t *drc_cred;
 } dmu_recv_cookie_t;

include/sys/dsl_bookmark.h

@@ -36,8 +36,25 @@ typedef struct zfs_bookmark_phys {
 	uint64_t zbm_guid;		/* guid of bookmarked dataset */
 	uint64_t zbm_creation_txg;	/* birth transaction group */
 	uint64_t zbm_creation_time;	/* bookmark creation time */
+
+	/* the following fields are reserved for redacted send / recv */
+	uint64_t zbm_redaction_obj;	/* redaction list object */
+	uint64_t zbm_flags;		/* ZBM_FLAG_* */
+	uint64_t zbm_referenced_bytes_refd;
+	uint64_t zbm_compressed_bytes_refd;
+	uint64_t zbm_uncompressed_bytes_refd;
+	uint64_t zbm_referenced_freed_before_next_snap;
+	uint64_t zbm_compressed_freed_before_next_snap;
+	uint64_t zbm_uncompressed_freed_before_next_snap;
+
+	/* fields used for raw sends */
+	uint64_t zbm_ivset_guid;
 } zfs_bookmark_phys_t;
 
+
+#define	BOOKMARK_PHYS_SIZE_V1	(3 * sizeof (uint64_t))
+#define	BOOKMARK_PHYS_SIZE_V2	(12 * sizeof (uint64_t))
+
 int dsl_bookmark_create(nvlist_t *, nvlist_t *);
 int dsl_get_bookmarks(const char *, nvlist_t *, nvlist_t *);
 int dsl_get_bookmarks_impl(dsl_dataset_t *, nvlist_t *, nvlist_t *);

include/sys/dsl_crypt.h

@@ -189,12 +189,13 @@ void key_mapping_rele(spa_t *spa, dsl_key_mapping_t *km, void *tag);
 int spa_keystore_lookup_key(spa_t *spa, uint64_t dsobj, void *tag,
     dsl_crypto_key_t **dck_out);
 
-int dsl_crypto_populate_key_nvlist(struct dsl_dataset *ds, nvlist_t **nvl_out);
+int dsl_crypto_populate_key_nvlist(struct dsl_dataset *ds,
+    uint64_t from_ivset_guid, nvlist_t **nvl_out);
 int dsl_crypto_recv_raw_key_check(struct dsl_dataset *ds,
     nvlist_t *nvl, dmu_tx_t *tx);
 void dsl_crypto_recv_raw_key_sync(struct dsl_dataset *ds,
     nvlist_t *nvl, dmu_tx_t *tx);
-int dsl_crypto_recv_raw(const char *poolname, uint64_t dsobj,
+int dsl_crypto_recv_raw(const char *poolname, uint64_t dsobj, uint64_t fromobj,
     dmu_objset_type_t ostype, nvlist_t *nvl, boolean_t do_key);
 
 int spa_keystore_change_key(const char *dsname, dsl_crypto_params_t *dcp);

include/sys/dsl_dataset.h

@@ -114,6 +114,12 @@ struct dsl_key_mapping;
  */
 #define	DS_FIELD_REMAP_DEADLIST	"com.delphix:remap_deadlist"
 
+/*
+ * This field is set to the ivset guid for encrypted snapshots. This is used
+ * for validating raw receives.
+ */
+#define	DS_FIELD_IVSET_GUID	"com.datto:ivset_guid"
+
 /*
  * DS_FLAG_CI_DATASET is set if the dataset contains a file system whose
  * name lookups should be performed case-insensitively.

include/sys/fs/zfs.h

@@ -183,6 +183,7 @@ typedef enum {
 	ZFS_PROP_KEYSTATUS,
 	ZFS_PROP_REMAPTXG,		/* not exposed to the user */
 	ZFS_PROP_SPECIAL_SMALL_BLOCKS,
+	ZFS_PROP_IVSET_GUID,		/* not exposed to the user */
 	ZFS_NUM_PROPS
 } zfs_prop_t;
 
@@ -1256,6 +1257,7 @@ typedef enum {
 	ZFS_ERR_IOC_ARG_UNAVAIL,
 	ZFS_ERR_IOC_ARG_REQUIRED,
 	ZFS_ERR_IOC_ARG_BADTYPE,
+	ZFS_ERR_FROM_IVSET_GUID_MISMATCH,
 } zfs_errno_t;
 
 /*

lib/libzfs/libzfs_sendrecv.c

@@ -4281,6 +4281,13 @@ zfs_receive_one(libzfs_handle_t *hdl, int infd, const char *tosnap,
 			    "destination %s space quota exceeded."), name);
 			(void) zfs_error(hdl, EZFS_NOSPC, errbuf);
 			break;
+		case ZFS_ERR_FROM_IVSET_GUID_MISMATCH:
+			zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
+			    "IV set guid mismatch. See the 'zfs receive' "
+			    "man page section\n discussing the limitations "
+			    "of raw encrypted send streams."));
+			(void) zfs_error(hdl, EZFS_BADSTREAM, errbuf);
+			break;
 		case EBUSY:
 			if (hastoken) {
 				zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,

man/man8/zfs.8

@@ -3816,6 +3816,31 @@ parameters with the
 .Fl o
 options.
 .Pp
+The added security provided by raw sends adds some restrictions to the send
+and receive process. ZFS will not allow a mix of raw receives and non-raw
+receives. Specifically, any raw incremental receives that are attempted after
+a non-raw receive will fail. Non-raw receives do not have this restriction and,
+therefore, are always possible. Because of this, it is best practice to always
+use either raw sends for their security benefits or non-raw sends for their
+flexibility when working with encrypted datasets, but not a combination.
+.Pp
+The reason for this restriction stems from the inherent restrictions of the
+AEAD ciphers that ZFS uses to encrypt data. When using ZFS native encryption,
+each block of data is encrypted against a randomly generated number known as
+the "initialization vector" (IV), which is stored in the filesystem metadata.
+This number is required by the encryption algorithms whenever the data is to
+be decrypted. Together, all of the IVs provided for all of the blocks in a
+given snapshot are collectively called an "IV set". When ZFS performs a raw
+send, the IV set is transferred from the source to the destination in the send
+stream. When ZFS performs a non-raw send, the data is decrypted by the source
+system and re-encrypted by the destination system, creating a snapshot with
+effectively the same data, but a different IV set. In order for decryption to
+work after a raw send, ZFS must ensure that the IV set used on both the source
+and destination side match. When an incremental raw receive is performed on
+top of an existing snapshot, ZFS will check to confirm that the "from"
+snapshot on both the source and destination were using the same IV set,
+ensuring the new IV set is consistent.
+.Pp
 The name of the snapshot
 .Pq and file system, if a full stream is received
 that this subcommand creates depends on the argument type and the use of the

module/zcommon/zfs_prop.c

@@ -559,6 +559,8 @@ zfs_prop_init(void)
 	    PROP_READONLY, ZFS_TYPE_DATASET, "UNIQUE");
 	zprop_register_hidden(ZFS_PROP_INCONSISTENT, "inconsistent",
 	    PROP_TYPE_NUMBER, PROP_READONLY, ZFS_TYPE_DATASET, "INCONSISTENT");
+	zprop_register_hidden(ZFS_PROP_IVSET_GUID, "ivsetguid",
+	    PROP_TYPE_NUMBER, PROP_READONLY, ZFS_TYPE_SNAPSHOT, "IVSETGUID");
 	zprop_register_hidden(ZFS_PROP_PREV_SNAP, "prevsnap", PROP_TYPE_STRING,
 	    PROP_READONLY, ZFS_TYPE_FILESYSTEM | ZFS_TYPE_VOLUME, "PREVSNAP");
 	zprop_register_hidden(ZFS_PROP_PBKDF2_SALT, "pbkdf2salt",

module/zfs/dmu_recv.c

@@ -71,7 +71,6 @@ typedef struct dmu_recv_begin_arg {
 	dmu_recv_cookie_t *drba_cookie;
 	cred_t *drba_cred;
 	dsl_crypto_params_t *drba_dcp;
-	uint64_t drba_snapobj;
 } dmu_recv_begin_arg_t;
 
 static int
@@ -117,7 +116,7 @@ recv_begin_check_existing_impl(dmu_recv_begin_arg_t *drba, dsl_dataset_t *ds,
 		dsl_dataset_t *snap;
 		uint64_t obj = dsl_dataset_phys(ds)->ds_prev_snap_obj;
 
-		/* Can't perform a raw receive on top of a non-raw receive */
+		/* Can't raw receive on top of an unencrypted dataset */
 		if (!encrypted && raw)
 			return (SET_ERROR(EINVAL));
 
@@ -144,7 +143,7 @@ recv_begin_check_existing_impl(dmu_recv_begin_arg_t *drba, dsl_dataset_t *ds,
 			return (SET_ERROR(ENODEV));
 
 		if (drba->drba_cookie->drc_force) {
-			drba->drba_snapobj = obj;
+			drba->drba_cookie->drc_fromsnapobj = obj;
 		} else {
 			/*
 			 * If we are not forcing, there must be no
@@ -154,7 +153,8 @@ recv_begin_check_existing_impl(dmu_recv_begin_arg_t *drba, dsl_dataset_t *ds,
 				dsl_dataset_rele(snap, FTAG);
 				return (SET_ERROR(ETXTBSY));
 			}
-			drba->drba_snapobj = ds->ds_prev->ds_object;
+			drba->drba_cookie->drc_fromsnapobj =
+			    ds->ds_prev->ds_object;
 		}
 
 		dsl_dataset_rele(snap, FTAG);
@@ -189,7 +189,7 @@ recv_begin_check_existing_impl(dmu_recv_begin_arg_t *drba, dsl_dataset_t *ds,
 				return (SET_ERROR(EINVAL));
 		}
 
-		drba->drba_snapobj = 0;
+		drba->drba_cookie->drc_fromsnapobj = 0;
 	}
 
 	return (0);
@@ -416,7 +416,7 @@ dmu_recv_begin_sync(void *arg, dmu_tx_t *tx)
 	 * the raw cmd set. Raw incremental recvs do not use a dcp
 	 * since the encryption parameters are already set in stone.
 	 */
-	if (dcp == NULL && drba->drba_snapobj == 0 &&
+	if (dcp == NULL && drba->drba_cookie->drc_fromsnapobj == 0 &&
 	    drba->drba_origin == NULL) {
 		ASSERT3P(dcp, ==, NULL);
 		dcp = &dummy_dcp;
@@ -430,15 +430,15 @@ dmu_recv_begin_sync(void *arg, dmu_tx_t *tx)
 		/* create temporary clone */
 		dsl_dataset_t *snap = NULL;
 
-		if (drba->drba_snapobj != 0) {
+		if (drba->drba_cookie->drc_fromsnapobj != 0) {
 			VERIFY0(dsl_dataset_hold_obj(dp,
-			    drba->drba_snapobj, FTAG, &snap));
+			    drba->drba_cookie->drc_fromsnapobj, FTAG, &snap));
 			ASSERT3P(dcp, ==, NULL);
 		}
 
 		dsobj = dsl_dataset_create_sync(ds->ds_dir, recv_clone_name,
 		    snap, crflags, drba->drba_cred, dcp, tx);
-		if (drba->drba_snapobj != 0)
+		if (drba->drba_cookie->drc_fromsnapobj != 0)
 			dsl_dataset_rele(snap, FTAG);
 		dsl_dataset_rele_flags(ds, dsflags, FTAG);
 	} else {
@@ -2462,11 +2462,15 @@ dmu_recv_stream(dmu_recv_cookie_t *drc, vnode_t *vp, offset_t *voffp,
 		 * the keynvl away until then.
 		 */
 		err = dsl_crypto_recv_raw(spa_name(ra->os->os_spa),
-		    drc->drc_ds->ds_object, drc->drc_drrb->drr_type,
-		    keynvl, drc->drc_newfs);
+		    drc->drc_ds->ds_object, drc->drc_fromsnapobj,
+		    drc->drc_drrb->drr_type, keynvl, drc->drc_newfs);
 		if (err != 0)
 			goto out;
 
+		/* see comment in dmu_recv_end_sync() */
+		(void) nvlist_lookup_uint64(keynvl, "to_ivset_guid",
+		    &drc->drc_ivset_guid);
+
 		if (!drc->drc_newfs)
 			drc->drc_keynvl = fnvlist_dup(keynvl);
 	}
@@ -2774,6 +2778,22 @@ dmu_recv_end_sync(void *arg, dmu_tx_t *tx)
 		drc->drc_newsnapobj =
 		    dsl_dataset_phys(drc->drc_ds)->ds_prev_snap_obj;
 	}
+
+	/*
+	 * If this is a raw receive, the crypt_keydata nvlist will include
+	 * a to_ivset_guid for us to set on the new snapshot. Older
+	 * implementations of the raw send code did not have this field.
+	 * In this case the ivset guid will not be set which will disable
+	 * the check for this value.
+	 */
+	if (drc->drc_raw && drc->drc_ivset_guid != 0) {
+		dmu_object_zapify(dp->dp_meta_objset, drc->drc_newsnapobj,
+		    DMU_OT_DSL_DATASET, tx);
+		VERIFY0(zap_update(dp->dp_meta_objset, drc->drc_newsnapobj,
+		    DS_FIELD_IVSET_GUID, sizeof (uint64_t), 1,
+		    &drc->drc_ivset_guid, tx));
+	}
+
 	zvol_create_minors(dp->dp_spa, drc->drc_tofs, B_TRUE);
 
 	/*

module/zfs/dmu_send.c

@@ -1119,9 +1119,13 @@ dmu_send_impl(void *tag, dsl_pool_t *dp, dsl_dataset_t *to_ds,
 		}
 
 		if (featureflags & DMU_BACKUP_FEATURE_RAW) {
+			uint64_t ivset_guid = (ancestor_zb != NULL) ?
+			    ancestor_zb->zbm_ivset_guid : 0;
+
 			ASSERT(os->os_encrypted);
 
-			err = dsl_crypto_populate_key_nvlist(to_ds, &keynvl);
+			err = dsl_crypto_populate_key_nvlist(to_ds,
+			    ivset_guid, &keynvl);
 			if (err != 0) {
 				fnvlist_free(nvl);
 				goto out;
@@ -1235,7 +1239,7 @@ dmu_send_obj(const char *pool, uint64_t tosnap, uint64_t fromsnap,
 	}
 
 	if (fromsnap != 0) {
-		zfs_bookmark_phys_t zb;
+		zfs_bookmark_phys_t zb = { 0 };
 		boolean_t is_clone;
 
 		err = dsl_dataset_hold_obj(dp, fromsnap, FTAG, &fromds);
@@ -1244,12 +1248,25 @@ dmu_send_obj(const char *pool, uint64_t tosnap, uint64_t fromsnap,
 			dsl_pool_rele(dp, FTAG);
 			return (err);
 		}
-		if (!dsl_dataset_is_before(ds, fromds, 0))
+		if (!dsl_dataset_is_before(ds, fromds, 0)) {
 			err = SET_ERROR(EXDEV);
+			dsl_dataset_rele(fromds, FTAG);
+			dsl_dataset_rele_flags(ds, dsflags, FTAG);
+			dsl_pool_rele(dp, FTAG);
+			return (err);
+		}
+
 		zb.zbm_creation_time =
 		    dsl_dataset_phys(fromds)->ds_creation_time;
 		zb.zbm_creation_txg = dsl_dataset_phys(fromds)->ds_creation_txg;
 		zb.zbm_guid = dsl_dataset_phys(fromds)->ds_guid;
+
+		if (dsl_dataset_is_zapified(fromds)) {
+			(void) zap_lookup(dp->dp_meta_objset,
+			    fromds->ds_object, DS_FIELD_IVSET_GUID, 8, 1,
+			    &zb.zbm_ivset_guid);
+		}
+
 		is_clone = (fromds->ds_dir != ds->ds_dir);
 		dsl_dataset_rele(fromds, FTAG);
 		err = dmu_send_impl(FTAG, dp, ds, &zb, is_clone,
@@ -1299,7 +1316,7 @@ dmu_send(const char *tosnap, const char *fromsnap, boolean_t embedok,
 	}
 
 	if (fromsnap != NULL) {
-		zfs_bookmark_phys_t zb;
+		zfs_bookmark_phys_t zb = { 0 };
 		boolean_t is_clone = B_FALSE;
 		int fsnamelen = strchr(tosnap, '@') - tosnap;
 
@@ -1325,6 +1342,13 @@ dmu_send(const char *tosnap, const char *fromsnap, boolean_t embedok,
 				    dsl_dataset_phys(fromds)->ds_creation_txg;
 				zb.zbm_guid = dsl_dataset_phys(fromds)->ds_guid;
 				is_clone = (ds->ds_dir != fromds->ds_dir);
+
+				if (dsl_dataset_is_zapified(fromds)) {
+					(void) zap_lookup(dp->dp_meta_objset,
+					    fromds->ds_object,
+					    DS_FIELD_IVSET_GUID, 8, 1,
+					    &zb.zbm_ivset_guid);
+				}
 				dsl_dataset_rele(fromds, FTAG);
 			}
 		} else {

module/zfs/dsl_bookmark.c

@@ -70,6 +70,12 @@ dsl_dataset_bmark_lookup(dsl_dataset_t *ds, const char *shortname,
 	if (dsl_dataset_phys(ds)->ds_flags & DS_FLAG_CI_DATASET)
 		mt = MT_NORMALIZE;
 
+	/*
+	 * Zero out the bookmark in case the one stored on disk
+	 * is in an older, shorter format.
+	 */
+	bzero(bmark_phys, sizeof (*bmark_phys));
+
 	err = zap_lookup_norm(mos, bmark_zapobj, shortname, sizeof (uint64_t),
 	    sizeof (*bmark_phys) / sizeof (uint64_t), bmark_phys, mt,
 	    NULL, 0, NULL);
@@ -188,8 +194,9 @@ dsl_bookmark_create_sync(void *arg, dmu_tx_t *tx)
 	for (nvpair_t *pair = nvlist_next_nvpair(dbca->dbca_bmarks, NULL);
 	    pair != NULL; pair = nvlist_next_nvpair(dbca->dbca_bmarks, pair)) {
 		dsl_dataset_t *snapds, *bmark_fs;
-		zfs_bookmark_phys_t bmark_phys;
+		zfs_bookmark_phys_t bmark_phys = { 0 };
 		char *shortname;
+		uint32_t bmark_len = BOOKMARK_PHYS_SIZE_V1;
 
 		VERIFY0(dsl_dataset_hold(dp, fnvpair_value_string(pair),
 		    FTAG, &snapds));
@@ -214,10 +221,22 @@ dsl_bookmark_create_sync(void *arg, dmu_tx_t *tx)
 		bmark_phys.zbm_creation_time =
 		    dsl_dataset_phys(snapds)->ds_creation_time;
 
+		if (snapds->ds_dir->dd_crypto_obj != 0) {
+			/*
+			 * This value may not exist if the snapshot was
+			 * created on a version of zfs before this field
+			 * was added.
+			 */
+			int err = zap_lookup(mos, snapds->ds_object,
+			    DS_FIELD_IVSET_GUID, sizeof (uint64_t), 1,
+			    &bmark_phys.zbm_ivset_guid);
+			if (err == 0)
+				bmark_len = BOOKMARK_PHYS_SIZE_V2;
+		}
+
 		VERIFY0(zap_add(mos, bmark_fs->ds_bookmarks,
 		    shortname, sizeof (uint64_t),
-		    sizeof (zfs_bookmark_phys_t) / sizeof (uint64_t),
-		    &bmark_phys, tx));
+		    bmark_len / sizeof (uint64_t), &bmark_phys, tx));
 
 		spa_history_log_internal_ds(bmark_fs, "bookmark", tx,
 		    "name=%s creation_txg=%llu target_snap=%llu",