diff --git a/sys/dev/md/md.c b/sys/dev/md/md.c
--- a/sys/dev/md/md.c
+++ b/sys/dev/md/md.c
@@ -93,6 +93,7 @@
 #include <sys/unistd.h>
 #include <sys/vnode.h>
 #include <sys/disk.h>
+#include <sys/priv.h>
 
 #include <geom/geom.h>
 #include <geom/geom_int.h>
@@ -1777,6 +1778,9 @@
 	sc = mdfind(mdr->md_unit);
 	if (sc == NULL)
 		return (ENOENT);
+	if (priv_check(td, PRIV_VFS_ADMIN) != 0)
+		if (!sc->cred || cr_cansee(td->td_ucred, sc->cred))
+			return (EPERM);
 	if (sc->opencount != 0 && !(sc->flags & MD_FORCE) &&
 	    !(mdr->md_options & MD_FORCE))
 		return (EBUSY);
@@ -1795,7 +1799,7 @@
 }
 
 static int
-kern_mdresize_locked(struct md_req *mdr)
+kern_mdresize_locked(struct thread *td, struct md_req *mdr)
 {
 	struct md_s *sc;
 
@@ -1807,6 +1811,9 @@
 	sc = mdfind(mdr->md_unit);
 	if (sc == NULL)
 		return (ENOENT);
+	if (priv_check(td, PRIV_VFS_ADMIN) != 0)
+		if (!sc->cred || cr_cansee(td->td_ucred, sc->cred))
+			return (EPERM);
 	if (mdr->md_mediasize < sc->sectorsize)
 		return (EINVAL);
 	mdr->md_mediasize -= mdr->md_mediasize % sc->sectorsize;
@@ -1818,12 +1825,12 @@
 }
 
 static int
-kern_mdresize(struct md_req *mdr)
+kern_mdresize(struct thread *td, struct md_req *mdr)
 {
 	int error;
 
 	sx_xlock(&md_sx);
-	error = kern_mdresize_locked(mdr);
+	error = kern_mdresize_locked(td, mdr);
 	sx_xunlock(&md_sx);
 	return (error);
 }
@@ -1959,7 +1966,7 @@
 #ifdef COMPAT_FREEBSD32
 	case MDIOCRESIZE_32:
 #endif
-		error = kern_mdresize(&mdr);
+		error = kern_mdresize(td, &mdr);
 		break;
 	case MDIOCQUERY:
 #ifdef COMPAT_FREEBSD32