commit e7656b7200d934d6f77df422d6d3dee469230dea
author Tom Cherry <tomcherry@google.com> Mon May 01 17:10:09 2017 -0700
committer Tom Cherry <tomcherry@google.com> Mon May 01 17:22:49 2017 -0700
tree 9ef0aa7484486d201006d9dfd6f9deb03db0fc1b
parent 6a8314c8bfa4a182ddf560609ebb514ec30b32bf

ueventd: do not reference init's sehandle

Init exposes a global 'sehandle' that ueventd references as part of
devices.cpp and util.cpp.  This is particularly dangerous in
device_init() in which both uevent and init write to this global.

This change creates a separate local copy for devices.cpp and puts
restrictions on where init.h can be included to make sure the global
used by init is not reference by non-init code.  Future changes to
init should remove this global.

Test: Boot bullhead

Change-Id: Ifefa9e1932e9d647d06cca2618f5c8e5a7a85460

init/devices.cpp

diff --git a/init/devices.cpp b/init/devices.cpp
index 11687f0..74f099a 100644
--- a/init/devices.cpp
+++ b/init/devices.cpp
@@ -54,7 +54,11 @@
 #include "ueventd.h"
 #include "util.h"
 
-extern struct selabel_handle *sehandle;
+#ifdef _INIT_INIT_H
+#error "Do not include init.h in files used by ueventd or watchdogd; it will expose init's globals"
+#endif
+
+static selabel_handle* sehandle;
 
 static android::base::unique_fd device_fd;
 
@@ -554,7 +558,7 @@
 }
 
 static void make_link_init(const std::string& oldpath, const std::string& newpath) {
-    if (mkdir_recursive(dirname(newpath.c_str()), 0755)) {
+    if (mkdir_recursive(dirname(newpath.c_str()), 0755, sehandle)) {
         PLOG(ERROR) << "Failed to create directory " << dirname(newpath.c_str());
     }
 
@@ -599,7 +603,7 @@
     if (uevent->major < 0 || uevent->minor < 0) return;
 
     const char* base = "/dev/block/";
-    make_dir(base, 0755);
+    make_dir(base, 0755, sehandle);
 
     std::string name = android::base::Basename(uevent->path);
     std::string devpath = base + name;
@@ -641,7 +645,7 @@
         devpath = "/dev/" + android::base::Basename(uevent->path);
     }
 
-    mkdir_recursive(android::base::Dirname(devpath), 0755);
+    mkdir_recursive(android::base::Dirname(devpath), 0755, sehandle);
 
     auto links = get_character_device_symlinks(uevent);