Create sysfs_hwrandom type.

HwRngTest needs access to the hwrandom sysfs files, but untrused_app
does not have access to sysfs.  Give these files their own label and
allow the needed read access.

(cherry-pick from internal commit: 85c0f8af)

Bug: 27263241
Change-Id: If572ad0931a534d76e148b688b76687460e99af9

file.te

@@ -25,6 +25,7 @@ type sysfs, fs_type, sysfs_type, mlstrustedobject;
 type sysfs_writable, fs_type, sysfs_type, mlstrustedobject;
 type sysfs_batteryinfo, fs_type, sysfs_type;
 type sysfs_bluetooth_writable, fs_type, sysfs_type, mlstrustedobject;
+type sysfs_hwrandom, fs_type, sysfs_type;
 type sysfs_nfc_power_writable, fs_type, sysfs_type, mlstrustedobject;
 type sysfs_wake_lock, fs_type, sysfs_type;
 type sysfs_mac_address, fs_type, sysfs_type;

file_contexts

@@ -327,6 +327,7 @@
 /sys/devices/system/cpu(/.*)?    u:object_r:sysfs_devices_system_cpu:s0
 /sys/devices/virtual/block/zram\d+(/.*)?     u:object_r:sysfs_zram:s0
 /sys/devices/virtual/block/zram\d+/uevent    u:object_r:sysfs_zram_uevent:s0
+/sys/devices/virtual/misc/hw_random(/.*)?    u:object_r:sysfs_hwrandom:s0
 /sys/power/wake_lock -- u:object_r:sysfs_wake_lock:s0
 /sys/power/wake_unlock -- u:object_r:sysfs_wake_lock:s0
 /sys/kernel/uevent_helper --	u:object_r:usermodehelper:s0

ueventd.te

@@ -13,6 +13,7 @@ allow ueventd self:capability { chown mknod net_admin setgid fsetid sys_rawio da
 allow ueventd device:file create_file_perms;
 allow ueventd device:chr_file rw_file_perms;
 allow ueventd sysfs:file rw_file_perms;
+allow ueventd sysfs_hwrandom:file w_file_perms;
 allow ueventd sysfs_zram_uevent:file w_file_perms;
 allow ueventd sysfs_type:{ file lnk_file } { relabelfrom relabelto setattr getattr };
 allow ueventd sysfs_type:dir { relabelfrom relabelto setattr r_dir_perms };

untrusted_app.te

@@ -95,6 +95,10 @@ allow untrusted_app proc_meminfo:file r_file_perms;
 # access /proc/net/xt_qtguid/stats
 r_dir_file(untrusted_app, proc_net)
 
+# Cts: HwRngTest
+allow untrusted_app sysfs_hwrandom:dir search;
+allow untrusted_app sysfs_hwrandom:file r_file_perms;
+
 ###
 ### neverallow rules
 ###