Disallow attaching preloaded memory disks via ioctl.

- The feature is dangerous because the kernel code didn't check
  validity of the memory address provided from user space.
- It seems that mdconfig(8) never really supported attaching preloaded
  memory disks.
- Preloaded memory disks are automatically attached during md(4)
  initialization. Thus there shouldn't be much use for the feature.

PR:		kern/169683
Discussed on:	freebsd-hackers

1 files changed, 6 insertions, 23 deletions

diff --git a/sys/dev/md/md.c b/sys/dev/md/md.c
index 443c127..00ef7e5 100644
--- a/sys/dev/md/md.c
+++ b/sys/dev/md/md.c
@@ -854,27 +854,6 @@ mdinit(struct md_s *sc)
 	    DEVSTAT_ALL_SUPPORTED, DEVSTAT_TYPE_DIRECT, DEVSTAT_PRIORITY_MAX);
 }
 
-/*
- * XXX: we should check that the range they feed us is mapped.
- * XXX: we should implement read-only.
- */
-
-static int
-mdcreate_preload(struct md_s *sc, struct md_ioctl *mdio)
-{
-
-	if (mdio->md_options & ~(MD_AUTOUNIT | MD_FORCE))
-		return (EINVAL);
-	if (mdio->md_base == 0)
-		return (EINVAL);
-	sc->flags = mdio->md_options & MD_FORCE;
-	/* Cast to pointer size, then to pointer to avoid warning */
-	sc->pl_ptr = (u_char *)(uintptr_t)mdio->md_base;
-	sc->pl_len = (size_t)sc->mediasize;
-	return (0);
-}
-
-
 static int
 mdcreate_malloc(struct md_s *sc, struct md_ioctl *mdio)
 {
@@ -1238,8 +1217,12 @@ xmdctlioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags, struct thread
 			error = mdcreate_malloc(sc, mdio);
 			break;
 		case MD_PRELOAD:
-			sc->start = mdstart_preload;
-			error = mdcreate_preload(sc, mdio);
+			/*
+			 * We disallow attaching preloaded memory disks via
+			 * ioctl. Preloaded memory disks are automatically
+			 * attached in g_md_init().
+			 */
+			error = EOPNOTSUPP;
 			break;
 		case MD_VNODE:
 			sc->start = mdstart_vnode;