Decryption error handling improvements

Currently, the decryption and block authentication code in
the ZIO / ARC layers is a bit inconsistent with regards to
the ereports that are produces and the error codes that are
passed to calling functions. This patch ensures that all of
these errors (which begin as ECKSUM) are converted to EIO
before they leave the ZIO or ARC layer and that ereports
are correctly generated on each decryption / authentication
failure.

In addition, this patch fixes a bug in zio_decrypt() where
ECKSUM never gets written to zio->io_error.

Reviewed by: Matt Ahrens <matt@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes #7372

include/sys/arc.h

@@ -237,7 +237,7 @@ boolean_t arc_is_unauthenticated(arc_buf_t *buf);
 enum zio_compress arc_get_compression(arc_buf_t *buf);
 void arc_get_raw_params(arc_buf_t *buf, boolean_t *byteorder, uint8_t *salt,
     uint8_t *iv, uint8_t *mac);
-int arc_untransform(arc_buf_t *buf, spa_t *spa, uint64_t dsobj,
+int arc_untransform(arc_buf_t *buf, spa_t *spa, const zbookmark_phys_t *zb,
     boolean_t in_place);
 void arc_convert_to_raw(arc_buf_t *buf, uint64_t dsobj, boolean_t byteorder,
     dmu_object_type_t ot, const uint8_t *salt, const uint8_t *iv,

include/sys/spa.h

@@ -1024,7 +1024,8 @@ extern void spa_history_log_internal_dd(dsl_dir_t *dd, const char *operation,
 struct zbookmark_phys;
 extern void spa_log_error(spa_t *spa, const zbookmark_phys_t *zb);
 extern void zfs_ereport_post(const char *class, spa_t *spa, vdev_t *vd,
-    zbookmark_phys_t *zb, zio_t *zio, uint64_t stateoroffset, uint64_t length);
+    const zbookmark_phys_t *zb, zio_t *zio, uint64_t stateoroffset,
+    uint64_t length);
 extern nvlist_t *zfs_event_create(spa_t *spa, vdev_t *vd, const char *type,
     const char *name, nvlist_t *aux);
 extern void zfs_post_remove(spa_t *spa, vdev_t *vd);

include/sys/zio.h

@@ -649,17 +649,18 @@ extern hrtime_t zio_handle_io_delay(zio_t *zio);
  * Checksum ereport functions
  */
 extern void zfs_ereport_start_checksum(spa_t *spa, vdev_t *vd,
-    zbookmark_phys_t *zb, struct zio *zio, uint64_t offset, uint64_t length,
-    void *arg, struct zio_bad_cksum *info);
+    const zbookmark_phys_t *zb, struct zio *zio, uint64_t offset,
+    uint64_t length, void *arg, struct zio_bad_cksum *info);
 extern void zfs_ereport_finish_checksum(zio_cksum_report_t *report,
     const abd_t *good_data, const abd_t *bad_data, boolean_t drop_if_identical);
 
 extern void zfs_ereport_free_checksum(zio_cksum_report_t *report);
 
 /* If we have the good data in hand, this function can be used */
 extern void zfs_ereport_post_checksum(spa_t *spa, vdev_t *vd,
-    zbookmark_phys_t *zb, struct zio *zio, uint64_t offset, uint64_t length,
-    const abd_t *good_data, const abd_t *bad_data, struct zio_bad_cksum *info);
+    const zbookmark_phys_t *zb, struct zio *zio, uint64_t offset,
+    uint64_t length, const abd_t *good_data, const abd_t *bad_data,
+    struct zio_bad_cksum *info);
 
 /* Called from spa_sync(), but primarily an injection handler */
 extern void spa_handle_ignored_writes(spa_t *spa);

module/zfs/arc.c

@@ -2260,14 +2260,27 @@ arc_buf_fill(arc_buf_t *buf, spa_t *spa, uint64_t dsobj, arc_fill_flags_t flags)
  * callers.
  */
 int
-arc_untransform(arc_buf_t *buf, spa_t *spa, uint64_t dsobj, boolean_t in_place)
+arc_untransform(arc_buf_t *buf, spa_t *spa, const zbookmark_phys_t *zb,
+    boolean_t in_place)
 {
+	int ret;
 	arc_fill_flags_t flags = 0;
 
 	if (in_place)
 		flags |= ARC_FILL_IN_PLACE;
 
-	return (arc_buf_fill(buf, spa, dsobj, flags));
+	ret = arc_buf_fill(buf, spa, zb->zb_objset, flags);
+	if (ret == ECKSUM) {
+		/*
+		 * Convert authentication and decryption errors to EIO
+		 * (and generate an ereport) before leaving the ARC.
+		 */
+		ret = SET_ERROR(EIO);
+		zfs_ereport_post(FM_EREPORT_ZFS_AUTHENTICATION,
+		    spa, NULL, zb, NULL, 0, 0);
+	}
+
+	return (ret);
 }
 
 /*
@@ -5810,7 +5823,8 @@ arc_read_done(zio_t *zio)
 		 * Assert non-speculative zios didn't fail because an
 		 * encryption key wasn't loaded
 		 */
-		ASSERT((zio->io_flags & ZIO_FLAG_SPECULATIVE) || error == 0);
+		ASSERT((zio->io_flags & ZIO_FLAG_SPECULATIVE) ||
+		    error != ENOENT);
 
 		/*
 		 * If we failed to decrypt, report an error now (as the zio
@@ -6033,12 +6047,24 @@ arc_read(zio_t *pio, spa_t *spa, const blkptr_t *bp,
 			rc = arc_buf_alloc_impl(hdr, spa, zb->zb_objset,
 			    private, encrypted_read, compressed_read,
 			    noauth_read, B_TRUE, &buf);
+			if (rc == ECKSUM) {
+				/*
+				 * Convert authentication and decryption errors
+				 * to EIO (and generate an ereport) before
+				 * leaving the ARC.
+				 */
+				rc = SET_ERROR(EIO);
+				zfs_ereport_post(FM_EREPORT_ZFS_AUTHENTICATION,
+				    spa, NULL, zb, NULL, 0, 0);
+			}
 			if (rc != 0) {
 				arc_buf_destroy(buf, private);
 				buf = NULL;
 			}
 
-			ASSERT((zio_flags & ZIO_FLAG_SPECULATIVE) || rc == 0);
+			/* assert any errors weren't due to unloaded keys */
+			ASSERT((zio_flags & ZIO_FLAG_SPECULATIVE) ||
+			    rc != ENOENT);
 		} else if (*arc_flags & ARC_FLAG_PREFETCH &&
 		    refcount_count(&hdr->b_l1hdr.b_refcnt) == 0) {
 			arc_hdr_set_flags(hdr, ARC_FLAG_PREFETCH);

module/zfs/dbuf.c

@@ -1194,8 +1194,10 @@ dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
 		    DMU_OT_IS_ENCRYPTED(dn->dn_bonustype) &&
 		    (flags & DB_RF_NO_DECRYPT) == 0 &&
 		    arc_is_encrypted(dn_buf)) {
+			SET_BOOKMARK(&zb, dmu_objset_id(db->db_objset),
+			    DMU_META_DNODE_OBJECT, 0, dn->dn_dbuf->db_blkid);
 			err = arc_untransform(dn_buf, dn->dn_objset->os_spa,
-			    dmu_objset_id(dn->dn_objset), B_TRUE);
+			    &zb, B_TRUE);
 			if (err != 0) {
 				DB_DNODE_EXIT(db);
 				mutex_exit(&db->db_mtx);
@@ -1264,8 +1266,7 @@ dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
 	if (DBUF_IS_L2CACHEABLE(db))
 		aflags |= ARC_FLAG_L2CACHE;
 
-	SET_BOOKMARK(&zb, db->db_objset->os_dsl_dataset ?
-	    db->db_objset->os_dsl_dataset->ds_object : DMU_META_OBJSET,
+	SET_BOOKMARK(&zb, dmu_objset_id(db->db_objset),
 	    db->db.db_object, db->db_level, db->db_blkid);
 
 	/*
@@ -1409,9 +1410,12 @@ dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
 		if (db->db_buf != NULL && (flags & DB_RF_NO_DECRYPT) == 0 &&
 		    (arc_is_encrypted(db->db_buf) ||
 		    arc_get_compression(db->db_buf) != ZIO_COMPRESS_OFF)) {
+			zbookmark_phys_t zb;
+
+			SET_BOOKMARK(&zb, dmu_objset_id(db->db_objset),
+			    db->db.db_object, db->db_level, db->db_blkid);
 			dbuf_fix_old_data(db, spa_syncing_txg(spa));
-			err = arc_untransform(db->db_buf, spa,
-			    dmu_objset_id(db->db_objset), B_FALSE);
+			err = arc_untransform(db->db_buf, spa, &zb, B_FALSE);
 			dbuf_set_data(db, db->db_buf);
 		}
 		mutex_exit(&db->db_mtx);
@@ -3458,15 +3462,19 @@ dbuf_check_crypt(dbuf_dirty_record_t *dr)
 	ASSERT(MUTEX_HELD(&db->db_mtx));
 
 	if (!dr->dt.dl.dr_raw && arc_is_encrypted(db->db_buf)) {
+		zbookmark_phys_t zb;
+
 		/*
 		 * Unfortunately, there is currently no mechanism for
 		 * syncing context to handle decryption errors. An error
 		 * here is only possible if an attacker maliciously
 		 * changed a dnode block and updated the associated
 		 * checksums going up the block tree.
 		 */
+		SET_BOOKMARK(&zb, dmu_objset_id(db->db_objset),
+		    db->db.db_object, db->db_level, db->db_blkid);
 		err = arc_untransform(db->db_buf, db->db_objset->os_spa,
-		    dmu_objset_id(db->db_objset), B_TRUE);
+		    &zb, B_TRUE);
 		if (err)
 			panic("Invalid dnode block MAC");
 	} else if (dr->dt.dl.dr_raw) {

module/zfs/dmu_objset.c

@@ -686,8 +686,12 @@ dmu_objset_own_impl(dsl_dataset_t *ds, dmu_objset_type_t type,
 
 	/* if we are decrypting, we can now check MACs in os->os_phys_buf */
 	if (decrypt && arc_is_unauthenticated((*osp)->os_phys_buf)) {
+		zbookmark_phys_t zb;
+
+		SET_BOOKMARK(&zb, ds->ds_object, ZB_ROOT_OBJECT,
+		    ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
 		err = arc_untransform((*osp)->os_phys_buf, (*osp)->os_spa,
-		    ds->ds_object, B_FALSE);
+		    &zb, B_FALSE);
 		if (err != 0)
 			return (err);
 

module/zfs/dmu_send.c

@@ -983,8 +983,12 @@ dmu_send_impl(void *tag, dsl_pool_t *dp, dsl_dataset_t *to_ds,
 	 */
 	if (!rawok && os->os_encrypted &&
 	    arc_is_unauthenticated(os->os_phys_buf)) {
+		zbookmark_phys_t zb;
+
+		SET_BOOKMARK(&zb, to_ds->ds_object, ZB_ROOT_OBJECT,
+		    ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
 		err = arc_untransform(os->os_phys_buf, os->os_spa,
-		    to_ds->ds_object, B_FALSE);
+		    &zb, B_FALSE);
 		if (err != 0) {
 			dsl_pool_rele(dp, tag);
 			return (err);

module/zfs/zfs_fm.c

@@ -142,7 +142,7 @@ zfs_is_ratelimiting_event(const char *subclass, vdev_t *vd)
 
 static void
 zfs_ereport_start(nvlist_t **ereport_out, nvlist_t **detector_out,
-    const char *subclass, spa_t *spa, vdev_t *vd, zbookmark_phys_t *zb,
+    const char *subclass, spa_t *spa, vdev_t *vd, const zbookmark_phys_t *zb,
     zio_t *zio, uint64_t stateoroffset, uint64_t size)
 {
 	nvlist_t *ereport, *detector;
@@ -767,7 +767,8 @@ annotate_ecksum(nvlist_t *ereport, zio_bad_cksum_t *info,
 
 void
 zfs_ereport_post(const char *subclass, spa_t *spa, vdev_t *vd,
-    zbookmark_phys_t *zb, zio_t *zio, uint64_t stateoroffset, uint64_t size)
+    const zbookmark_phys_t *zb, zio_t *zio, uint64_t stateoroffset,
+    uint64_t size)
 {
 #ifdef _KERNEL
 	nvlist_t *ereport = NULL;
@@ -788,7 +789,7 @@ zfs_ereport_post(const char *subclass, spa_t *spa, vdev_t *vd,
 }
 
 void
-zfs_ereport_start_checksum(spa_t *spa, vdev_t *vd, zbookmark_phys_t *zb,
+zfs_ereport_start_checksum(spa_t *spa, vdev_t *vd, const zbookmark_phys_t *zb,
     struct zio *zio, uint64_t offset, uint64_t length, void *arg,
     zio_bad_cksum_t *info)
 {
@@ -874,7 +875,7 @@ zfs_ereport_free_checksum(zio_cksum_report_t *rpt)
 
 
 void
-zfs_ereport_post_checksum(spa_t *spa, vdev_t *vd, zbookmark_phys_t *zb,
+zfs_ereport_post_checksum(spa_t *spa, vdev_t *vd, const zbookmark_phys_t *zb,
     struct zio *zio, uint64_t offset, uint64_t length,
     const abd_t *good_data, const abd_t *bad_data, zio_bad_cksum_t *zbc)
 {

module/zfs/zio.c

@@ -506,7 +506,7 @@ zio_decrypt(zio_t *zio, abd_t *data, uint64_t size)
 	 * the io_error. If this was not a speculative zio, create an ereport.
 	 */
 	if (ret == ECKSUM) {
-		ret = SET_ERROR(EIO);
+		zio->io_error = SET_ERROR(EIO);
 		if ((zio->io_flags & ZIO_FLAG_SPECULATIVE) == 0) {
 			zfs_ereport_post(FM_EREPORT_ZFS_AUTHENTICATION,
 			    spa, NULL, &zio->io_bookmark, zio, 0, 0);