From: Harald Hoyer <harald@redhat.com>
Date: Thu, 20 Oct 2011 08:05:20 +0000 (+0200)
Subject: switch_root: handle /run and do not mount over existing mounts
X-Git-Tag: v2.21-rc1~328
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=acb03ad46a0f5160fe7a1c9d9ec09c35494d3051;p=thirdparty%2Futil-linux.git

switch_root: handle /run and do not mount over existing mounts

Handle /run just like /dev, /sys and /proc

Do not mount move, if there is already something mounted on the
destination folder.

Signed-off-by: Harald Hoyer <harald@redhat.com>
Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/sys-utils/switch_root.c b/sys-utils/switch_root.c
index 2dfed71a06..f86b8c697a 100644
--- a/sys-utils/switch_root.c
+++ b/sys-utils/switch_root.c
@@ -111,16 +111,28 @@ done:
 static int switchroot(const char *newroot)
 {
 	/*  Don't try to unmount the old "/", there's no way to do it. */
-	const char *umounts[] = { "/dev", "/proc", "/sys", NULL };
+	const char *umounts[] = { "/dev", "/proc", "/sys", "/run", NULL };
 	int i;
 	int cfd;
 	pid_t pid;
+	struct stat newroot_stat, sb;
+
+	if (stat(newroot, &newroot_stat) != 0) {
+		warn("failed to stat directory %s", newroot);
+		return -1;
+	}
 
 	for (i = 0; umounts[i] != NULL; i++) {
 		char newmount[PATH_MAX];
 
 		snprintf(newmount, sizeof(newmount), "%s%s", newroot, umounts[i]);
 
+		if ((stat(newmount, &sb) != 0) || (sb.st_dev != newroot_stat.st_dev)) {
+			/* mount point seems to be mounted already or stat failed */
+			umount(umounts[i]);
+			continue;
+		}
+
 		if (mount(umounts[i], newmount, NULL, MS_MOVE, NULL) < 0) {
 			warn("failed to mount moving %s to %s",
 				umounts[i], newmount);