From 2e8b15db5da0980fffbe98c0a2a3626c3e921021 Mon Sep 17 00:00:00 2001
From: krw <krw@openbsd.org>
Date: Mon, 12 Oct 2015 20:52:20 +0000
Subject: [PATCH] Check that the disk specified on the command line is the disk
 that files are copied to. Error out with 'cross-device install' if not.

ok millert@, ok deraadt@ & jsing@ for previous version
---
 usr.sbin/installboot/installboot.c | 19 +++++++++++++++++--
 usr.sbin/installboot/installboot.h |  4 +++-
 usr.sbin/installboot/util.c        | 19 +++++++++++++++----
 3 files changed, 35 insertions(+), 7 deletions(-)

diff --git a/usr.sbin/installboot/installboot.c b/usr.sbin/installboot/installboot.c
index f62f6b8c54b..f414af56aba 100644
--- a/usr.sbin/installboot/installboot.c
+++ b/usr.sbin/installboot/installboot.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: installboot.c,v 1.7 2015/10/08 14:50:38 krw Exp $	*/
+/*	$OpenBSD: installboot.c,v 1.8 2015/10/12 20:52:20 krw Exp $	*/
 
 /*
  * Copyright (c) 2012, 2013 Joel Sing <jsing@openbsd.org>
@@ -16,6 +16,9 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include <sys/types.h>
+#include <sys/disklabel.h>
+#include <sys/stat.h>
 #include <err.h>
 #include <fcntl.h>
 #include <stdio.h>
@@ -29,6 +32,8 @@
 int	nowrite;
 int	stages;
 int	verbose;
+int	dstblkunit;
+int	dstblkmajor;
 
 char	*root = "/";
 char	*stage1;
@@ -48,7 +53,8 @@ usage(void)
 int
 main(int argc, char **argv)
 {
-	char *dev, *realdev;
+	struct stat sb;
+	char *dev, *realdev, *blkdev;
 	int devfd, opt;
 
 	md_init();
@@ -101,6 +107,15 @@ main(int argc, char **argv)
 	    &realdev)) < 0)
 		err(1, "open: %s", realdev);
 
+	if (realdev == NULL || strncmp(realdev, "/dev/r", 6))
+		errx(1, "realdev");
+	if (asprintf(&blkdev, "/dev/%s", realdev+6) == -1)
+		err(1, "asprintf");
+	if (stat(blkdev, &sb) == -1)
+		err(1, "fstat");
+	dstblkunit = DISKUNIT(sb.st_rdev);
+	dstblkmajor = major(sb.st_rdev);
+
         if (verbose) {
 		fprintf(stderr, "%s bootstrap on %s\n",
 		    (nowrite ? "would install" : "installing"), realdev);
diff --git a/usr.sbin/installboot/installboot.h b/usr.sbin/installboot/installboot.h
index af23ea5f55c..5c9ad69c326 100644
--- a/usr.sbin/installboot/installboot.h
+++ b/usr.sbin/installboot/installboot.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: installboot.h,v 1.5 2015/10/08 14:50:38 krw Exp $	*/
+/*	$OpenBSD: installboot.h,v 1.6 2015/10/12 20:52:20 krw Exp $	*/
 /*
  * Copyright (c) 2012, 2013 Joel Sing <jsing@openbsd.org>
  *
@@ -18,6 +18,8 @@
 extern int nowrite;
 extern int stages;
 extern int verbose;
+extern int dstblkunit;
+extern int dstblkmajor;
 
 extern char *root;
 extern char *stage1;
diff --git a/usr.sbin/installboot/util.c b/usr.sbin/installboot/util.c
index ce830ea79d0..38206b83133 100644
--- a/usr.sbin/installboot/util.c
+++ b/usr.sbin/installboot/util.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: util.c,v 1.7 2015/10/08 14:50:38 krw Exp $	*/
+/*	$OpenBSD: util.c,v 1.8 2015/10/12 20:52:20 krw Exp $	*/
 
 /*
  * Copyright (c) 2014 Joel Sing <jsing@openbsd.org>
@@ -16,6 +16,8 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include <sys/types.h>
+#include <sys/disklabel.h>
 #include <sys/stat.h>
 #include <err.h>
 #include <errno.h>
@@ -36,7 +38,7 @@ int
 filecopy(const char *srcfile, const char *dstfile)
 {
 	struct stat sb;
-	ssize_t sz, n;
+	ssize_t srcsz, sz, n;
 	int sfd, dfd, rslt = -1;
 	char *buf;
 
@@ -54,13 +56,22 @@ filecopy(const char *srcfile, const char *dstfile)
 		warn("fstat");
 		return (-1);
 	}
-	sz = sb.st_size;
+	srcsz = sz = sb.st_size;
 
 	dfd = open(dstfile, O_WRONLY|O_CREAT);
 	if (dfd == -1) {
 		warn("open %s", dstfile);
 		return (-1);
 	}
+	if (fstat(dfd, &sb) == -1) {
+		warn("fstat");
+		return (-1);
+	}
+	if (major(sb.st_dev) != dstblkmajor || DISKUNIT(sb.st_dev) !=
+	    dstblkunit) {
+		warnx("cross-device install");
+		return (-1);
+	}
 	if (fchown(dfd, 0, 0) == -1)
 		if (errno != EINVAL) {
 			warn("chown");
@@ -84,7 +95,7 @@ filecopy(const char *srcfile, const char *dstfile)
 		}
 	}
 
-	ftruncate(dfd, sb.st_size);
+	ftruncate(dfd, srcsz);
 
 	close(dfd);
 	close(sfd);
-- 
2.20.1