Call realpath(3) in combination with chroot(2) and chdir(2).

Use umount(8) to check that the mountpoint leaks no vnode.
from Moritz Buhl

3 files changed, 180 insertions, 0 deletions

diff --git a/regress/sys/kern/realpath-unmount/Makefile b/regress/sys/kern/realpath-unmount/Makefile
new file mode 100644
index 00000000000..351650022d0
--- /dev/null
+++ b/regress/sys/kern/realpath-unmount/Makefile
@@ -0,0 +1,92 @@
+# $OpenBSD: Makefile,v 1.1.1.1 2019/08/05 15:16:39 bluhm Exp $
+
+# Call realpath(3) in combination with chroot(2), chdir(2).
+# Use umount(8) to check that the mountpoint leaks no vnode.
+# There were vnode reference counting bugs in the kernel.
+
+PROGS=		realpath-chroot realpath-chdir
+CLEANFILES=	diskimage
+
+.PHONY: mount unconfig clean
+
+diskimage: unconfig
+	@echo '\n======== $@ ========'
+	${SUDO} dd if=/dev/zero of=diskimage bs=512 count=4k
+	${SUDO} vnconfig vnd0 diskimage
+	${SUDO} newfs vnd0c
+
+mount: diskimage
+	@echo '\n======== $@ ========'
+	${SUDO} mkdir -p /mnt/regress-realpath
+	${SUDO} mount /dev/vnd0c /mnt/regress-realpath
+
+unconfig:
+	@echo '\n======== $@ ========'
+	-${SUDO} umount -f /dev/vnd0c 2>/dev/null || true
+	-${SUDO} rmdir /mnt/regress-realpath 2>/dev/null || true
+	-${SUDO} vnconfig -u vnd0 2>/dev/null || true
+	-${SUDO} rm -f stamp-setup
+
+REGRESS_SETUP	=	${PROGS} mount
+REGRESS_CLEANUP =	unconfig
+REGRESS_TARGETS =
+
+REGRESS_TARGETS +=	run-chroot
+run-chroot:
+	@echo '\n======== $@ ========'
+	${SUDO} mkdir -p /mnt/regress-realpath
+	${SUDO} ./realpath-chroot /mnt/regress-realpath /
+	${SUDO} umount /mnt/regress-realpath
+
+REGRESS_TARGETS +=	run-chroot-dir
+run-chroot-dir:
+	@echo '\n======== $@ ========'
+	${SUDO} mkdir -p /mnt/regress-realpath/foo
+	${SUDO} ./realpath-chroot /mnt/regress-realpath/foo /
+	${SUDO} umount /mnt/regress-realpath
+
+REGRESS_TARGETS +=	run-chroot-dir
+run-chroot-dir:
+	@echo '\n======== $@ ========'
+	${SUDO} mkdir -p /mnt/regress-realpath/foo
+	${SUDO} ./realpath-chroot /mnt/regress-realpath /foo
+	${SUDO} umount /mnt/regress-realpath
+
+REGRESS_TARGETS +=	run-chroot-dir-dir
+run-chroot-dir-dir:
+	@echo '\n======== $@ ========'
+	${SUDO} mkdir -p /mnt/regress-realpath/foo/bar
+	${SUDO} ./realpath-chroot /mnt/regress-realpath/foo /bar
+	${SUDO} umount /mnt/regress-realpath
+
+REGRESS_TARGETS +=	run-chdir
+run-chdir:
+	@echo '\n======== $@ ========'
+	${SUDO} mkdir -p /mnt/regress-realpath
+	${SUDO} ./realpath-chdir /mnt/regress-realpath .
+	${SUDO} umount /mnt/regress-realpath
+
+REGRESS_TARGETS +=	run-chdir-dir
+run-chdir-dir:
+	@echo '\n======== $@ ========'
+	${SUDO} mkdir -p /mnt/regress-realpath/foo
+	${SUDO} ./realpath-chdir /mnt/regress-realpath/foo .
+	${SUDO} umount /mnt/regress-realpath
+
+REGRESS_TARGETS +=	run-chdir-dir
+run-chdir-dir:
+	@echo '\n======== $@ ========'
+	${SUDO} mkdir -p /mnt/regress-realpath/foo
+	${SUDO} ./realpath-chdir /mnt/regress-realpath foo
+	${SUDO} umount /mnt/regress-realpath
+
+REGRESS_TARGETS +=	run-chdir-dir-dir
+run-chdir-dir-dir:
+	@echo '\n======== $@ ========'
+	${SUDO} mkdir -p /mnt/regress-realpath/foo/bar
+	${SUDO} ./realpath-chdir /mnt/regress-realpath/foo bar
+	${SUDO} umount /mnt/regress-realpath
+
+REGRESS_ROOT_TARGETS =	${REGRESS_TARGETS}
+
+.include <bsd.regress.mk>
diff --git a/regress/sys/kern/realpath-unmount/realpath-chdir.c b/regress/sys/kern/realpath-unmount/realpath-chdir.c
new file mode 100644
index 00000000000..03703ec297a
--- /dev/null
+++ b/regress/sys/kern/realpath-unmount/realpath-chdir.c
@@ -0,0 +1,44 @@
+/*	$OpenBSD: realpath-chdir.c,v 1.1.1.1 2019/08/05 15:16:39 bluhm Exp $	*/
+/*
+ * Copyright (c) 2019 Alexander Bluhm <bluhm@openbsd.org>
+ * Copyright (c) 2019 Moritz Buhl <mbuhl@moritzbuhl.de>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <err.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int
+main(int argc, char *argv[])
+{
+	char *cwd, *dir, *path = NULL;
+	char res[PATH_MAX];
+
+	if (argc != 3)
+		errx(2, "usage: realpath-chdir cwd dir");
+
+	cwd = argv[1];
+	dir = argv[2];
+
+	if (chdir(cwd) == -1)
+		err(1, "chdir %s", cwd);
+
+	if (realpath(dir, res) == NULL)
+		err(1, "realpath %s", dir);
+
+	return 0;
+}
diff --git a/regress/sys/kern/realpath-unmount/realpath-chroot.c b/regress/sys/kern/realpath-unmount/realpath-chroot.c
new file mode 100644
index 00000000000..72012aaf317
--- /dev/null
+++ b/regress/sys/kern/realpath-unmount/realpath-chroot.c
@@ -0,0 +1,44 @@
+/*	$OpenBSD: realpath-chroot.c,v 1.1.1.1 2019/08/05 15:16:39 bluhm Exp $	*/
+/*
+ * Copyright (c) 2019 Alexander Bluhm <bluhm@openbsd.org>
+ * Copyright (c) 2019 Moritz Buhl <mbuhl@moritzbuhl.de>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <err.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int
+main(int argc, char *argv[])
+{
+	char *root, *dir, *path = NULL;
+	char res[PATH_MAX];
+
+	if (argc != 3)
+		errx(2, "usage: realpath-chroot root dir");
+
+	root = argv[1];
+	dir = argv[2];
+
+	if (chroot(root) == -1)
+		err(1, "chroot %s", root);
+
+	if (realpath(dir, res) == NULL)
+		err(1, "realpath %s", dir);
+
+	return 0;
+}