commit b9f438ff841f87c8ffbca85b13a533718a18e15f
author Jeff Sharkey <jsharkey@android.com> Thu Aug 06 11:39:44 2015 -0700
committer Jeff Sharkey <jsharkey@android.com> Thu Aug 06 11:45:31 2015 -0700
tree 7705d99d1e1bcb8573f53c9f0adebbf5df125564
parent d57125af1a81f34b162ecd5de81e6f1365aff588

Protect runtime storage mount points.

We have a bunch of magic that mounts the correct view of storage
access based on the runtime permissions of an app, but we forgot to
protect the real underlying data sources; oops.

This series of changes just bumps the directory heirarchy one level
to give us /mnt/runtime which we can mask off as 0700 to prevent
people from jumping to the exposed internals.

Also add CTS tests to verify that we're protecting access to
internal mount points like this.

Bug: 22964288
Change-Id: I32068e63a3362b37e8ebca1418f900bb8537b498

rootdir/init.rc

diff --git a/rootdir/init.rc b/rootdir/init.rc
index 9019b1f..b71908c 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -69,16 +69,17 @@
 
     # Storage views to support runtime permissions
     mkdir /storage 0755 root root
-    mkdir /mnt/runtime_default 0755 root root
-    mkdir /mnt/runtime_default/self 0755 root root
-    mkdir /mnt/runtime_read 0755 root root
-    mkdir /mnt/runtime_read/self 0755 root root
-    mkdir /mnt/runtime_write 0755 root root
-    mkdir /mnt/runtime_write/self 0755 root root
+    mkdir /mnt/runtime 0700 root root
+    mkdir /mnt/runtime/default 0755 root root
+    mkdir /mnt/runtime/default/self 0755 root root
+    mkdir /mnt/runtime/read 0755 root root
+    mkdir /mnt/runtime/read/self 0755 root root
+    mkdir /mnt/runtime/write 0755 root root
+    mkdir /mnt/runtime/write/self 0755 root root
 
     # Symlink to keep legacy apps working in multi-user world
     symlink /storage/self/primary /sdcard
-    symlink /mnt/user/0/primary /mnt/runtime_default/self/primary
+    symlink /mnt/user/0/primary /mnt/runtime/default/self/primary
 
     # memory control cgroup
     mkdir /dev/memcg 0700 root system
@@ -216,7 +217,7 @@
     # Mount shared so changes propagate into child namespaces
     mount rootfs rootfs / shared rec
     # Mount default storage into root namespace
-    mount none /mnt/runtime_default /storage slave bind rec
+    mount none /mnt/runtime/default /storage slave bind rec
 
     # We chown/chmod /cache again so because mount is run as root + defaults
     chown system cache /cache

sdcard/sdcard.c

diff --git a/sdcard/sdcard.c b/sdcard/sdcard.c
index 41bf045..a79e2dd 100644
--- a/sdcard/sdcard.c
+++ b/sdcard/sdcard.c
@@ -1735,7 +1735,7 @@
             "    -g: specify GID to run as\n"
             "    -U: specify user ID that owns device\n"
             "    -m: source_path is multi-user\n"
-            "    -w: runtime_write mount has full write access\n"
+            "    -w: runtime write mount has full write access\n"
             "\n");
     return 1;
 }
@@ -1822,9 +1822,9 @@
     global.fuse_read = &fuse_read;
     global.fuse_write = &fuse_write;
 
-    snprintf(fuse_default.dest_path, PATH_MAX, "/mnt/runtime_default/%s", label);
-    snprintf(fuse_read.dest_path, PATH_MAX, "/mnt/runtime_read/%s", label);
-    snprintf(fuse_write.dest_path, PATH_MAX, "/mnt/runtime_write/%s", label);
+    snprintf(fuse_default.dest_path, PATH_MAX, "/mnt/runtime/default/%s", label);
+    snprintf(fuse_read.dest_path, PATH_MAX, "/mnt/runtime/read/%s", label);
+    snprintf(fuse_write.dest_path, PATH_MAX, "/mnt/runtime/write/%s", label);
 
     handler_default.fuse = &fuse_default;
     handler_read.fuse = &fuse_read;