1 files changed, 28 insertions, 15 deletions

diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zio.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zio.c
index 8548b2d..cce7fd1 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zio.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zio.c
@@ -330,7 +330,7 @@ zio_data_buf_free(void *buf, size_t size)
  */
 static void
 zio_push_transform(zio_t *zio, void *data, uint64_t size, uint64_t bufsize,
-	zio_transform_func_t *transform)
+    zio_transform_func_t *transform)
 {
 	zio_transform_t *zt = kmem_alloc(sizeof (zio_transform_t), KM_SLEEP);
 
@@ -999,7 +999,7 @@ zio_write_phys(zio_t *pio, vdev_t *vd, uint64_t offset, uint64_t size,
 
 	zio->io_prop.zp_checksum = checksum;
 
-	if (zio_checksum_table[checksum].ci_eck) {
+	if (zio_checksum_table[checksum].ci_flags & ZCHECKSUM_FLAG_EMBEDDED) {
 		/*
 		 * zec checksums are necessarily destructive -- they modify
 		 * the end of the write buffer to hold the verifier/checksum.
@@ -1068,8 +1068,8 @@ zio_vdev_child_io(zio_t *pio, blkptr_t *bp, vdev_t *vd, uint64_t offset,
 
 zio_t *
 zio_vdev_delegated_io(vdev_t *vd, uint64_t offset, void *data, uint64_t size,
-	int type, zio_priority_t priority, enum zio_flag flags,
-	zio_done_func_t *done, void *private)
+    int type, zio_priority_t priority, enum zio_flag flags,
+    zio_done_func_t *done, void *private)
 {
 	zio_t *zio;
 
@@ -1211,8 +1211,8 @@ zio_write_bp_init(zio_t *zio)
 		if (BP_IS_HOLE(bp) || !zp->zp_dedup)
 			return (ZIO_PIPELINE_CONTINUE);
 
-		ASSERT(zio_checksum_table[zp->zp_checksum].ci_dedup ||
-		    zp->zp_dedup_verify);
+		ASSERT((zio_checksum_table[zp->zp_checksum].ci_flags &
+		    ZCHECKSUM_FLAG_DEDUP) || zp->zp_dedup_verify);
 
 		if (BP_GET_CHECKSUM(bp) == zp->zp_checksum) {
 			BP_SET_DEDUP(bp, 1);
@@ -2074,12 +2074,22 @@ zio_write_gang_block(zio_t *pio)
 }
 
 /*
- * The zio_nop_write stage in the pipeline determines if allocating
- * a new bp is necessary.  By leveraging a cryptographically secure checksum,
- * such as SHA256, we can compare the checksums of the new data and the old
- * to determine if allocating a new block is required.  The nopwrite
- * feature can handle writes in either syncing or open context (i.e. zil
- * writes) and as a result is mutually exclusive with dedup.
+ * The zio_nop_write stage in the pipeline determines if allocating a
+ * new bp is necessary.  The nopwrite feature can handle writes in
+ * either syncing or open context (i.e. zil writes) and as a result is
+ * mutually exclusive with dedup.
+ *
+ * By leveraging a cryptographically secure checksum, such as SHA256, we
+ * can compare the checksums of the new data and the old to determine if
+ * allocating a new block is required.  Note that our requirements for
+ * cryptographic strength are fairly weak: there can't be any accidental
+ * hash collisions, but we don't need to be secure against intentional
+ * (malicious) collisions.  To trigger a nopwrite, you have to be able
+ * to write the file to begin with, and triggering an incorrect (hash
+ * collision) nopwrite is no worse than simply writing to the file.
+ * That said, there are no known attacks against the checksum algorithms
+ * used for nopwrite, assuming that the salt and the checksums
+ * themselves remain secret.
  */
 static int
 zio_nop_write(zio_t *zio)
@@ -2102,7 +2112,8 @@ zio_nop_write(zio_t *zio)
 	 * allocate a new bp.
 	 */
 	if (BP_IS_HOLE(bp_orig) ||
-	    !zio_checksum_table[BP_GET_CHECKSUM(bp)].ci_dedup ||
+	    !(zio_checksum_table[BP_GET_CHECKSUM(bp)].ci_flags &
+	    ZCHECKSUM_FLAG_NOPWRITE) ||
 	    BP_GET_CHECKSUM(bp) != BP_GET_CHECKSUM(bp_orig) ||
 	    BP_GET_COMPRESS(bp) != BP_GET_COMPRESS(bp_orig) ||
 	    BP_GET_DEDUP(bp) != BP_GET_DEDUP(bp_orig) ||
@@ -2114,7 +2125,8 @@ zio_nop_write(zio_t *zio)
 	 * avoid allocating a new bp and issuing any I/O.
 	 */
 	if (ZIO_CHECKSUM_EQUAL(bp->blk_cksum, bp_orig->blk_cksum)) {
-		ASSERT(zio_checksum_table[zp->zp_checksum].ci_dedup);
+		ASSERT(zio_checksum_table[zp->zp_checksum].ci_flags &
+		    ZCHECKSUM_FLAG_NOPWRITE);
 		ASSERT3U(BP_GET_PSIZE(bp), ==, BP_GET_PSIZE(bp_orig));
 		ASSERT3U(BP_GET_LSIZE(bp), ==, BP_GET_LSIZE(bp_orig));
 		ASSERT(zp->zp_compress != ZIO_COMPRESS_OFF);
@@ -2395,7 +2407,8 @@ zio_ddt_write(zio_t *zio)
 		 * we can't resolve it, so just convert to an ordinary write.
 		 * (And automatically e-mail a paper to Nature?)
 		 */
-		if (!zio_checksum_table[zp->zp_checksum].ci_dedup) {
+		if (!(zio_checksum_table[zp->zp_checksum].ci_flags &
+		    ZCHECKSUM_FLAG_DEDUP)) {
 			zp->zp_checksum = spa_dedup_checksum(spa);
 			zio_pop_transforms(zio);
 			zio->io_stage = ZIO_STAGE_OPEN;