Do not copy by field when converting struct oexport_args to struct

export_args on mount update, bzero() is consistent with
vfs_oexport_conv().
Make the code structure more explicit by using switch.
Return EINVAL if export option layout (deduced from size) is unknown.

Based on the submission by:	bde
Sponsored by:	The FreeBSD Foundation

1 files changed, 16 insertions, 18 deletions

diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
index 3ca995f..505da75 100644
--- a/sys/kern/vfs_mount.c
+++ b/sys/kern/vfs_mount.c
@@ -880,10 +880,10 @@ vfs_domount_update(
 	struct vfsoptlist **optlist	/* Options local to the filesystem. */
 	)
 {
-	struct oexport_args oexport;
 	struct export_args export;
+	void *bufp;
 	struct mount *mp;
-	int error, export_error;
+	int error, export_error, len;
 	uint64_t flag;
 
 	ASSERT_VOP_ELOCKED(vp, __func__);
@@ -951,23 +951,21 @@ vfs_domount_update(
 	error = VFS_MOUNT(mp);
 
 	export_error = 0;
-	if (error == 0) {
-		/* Process the export option. */
-		if (vfs_copyopt(mp->mnt_optnew, "export", &export,
-		    sizeof(export)) == 0) {
-			export_error = vfs_export(mp, &export);
-		} else if (vfs_copyopt(mp->mnt_optnew, "export", &oexport,
-		    sizeof(oexport)) == 0) {
-			export.ex_flags = oexport.ex_flags;
-			export.ex_root = oexport.ex_root;
-			export.ex_anon = oexport.ex_anon;
-			export.ex_addr = oexport.ex_addr;
-			export.ex_addrlen = oexport.ex_addrlen;
-			export.ex_mask = oexport.ex_mask;
-			export.ex_masklen = oexport.ex_masklen;
-			export.ex_indexfile = oexport.ex_indexfile;
-			export.ex_numsecflavors = 0;
+	/* Process the export option. */
+	if (error == 0 && vfs_getopt(mp->mnt_optnew, "export", &bufp,
+	    &len) == 0) {
+		/* Assume that there is only 1 ABI for each length. */
+		switch (len) {
+		case (sizeof(struct oexport_args)):
+			bzero(&export, sizeof(export));
+			/* FALLTHROUGH */
+		case (sizeof(export)):
+			bcopy(bufp, &export, len);
 			export_error = vfs_export(mp, &export);
+			break;
+		default:
+			export_error = EINVAL;
+			break;
 		}
 	}