Allow /dev/klog access, drop mknod and __null__ access

Allow vold, healthd, slideshow, and watchdogd access to /dev/kmsg.
These processes log to the kernel dmesg ring buffer, so they need
write access to that file.

Addresses the following denials:

    avc: denied { write } for pid=134 comm="watchdogd" name="kmsg" dev="tmpfs" ino=9248 scontext=u:r:watchdogd:s0 tcontext=u:object_r:kmsg_device:s0 tclass=chr_file permissive=0
    avc: denied { write } for pid=166 comm="healthd" name="kmsg" dev="tmpfs" ino=9248 scontext=u:r:healthd:s0 tcontext=u:object_r:kmsg_device:s0 tclass=chr_file permissive=0
    avc: denied { write } for pid=180 comm="vold" name="kmsg" dev="tmpfs" ino=9248 scontext=u:r:vold:s0 tcontext=u:object_r:kmsg_device:s0 tclass=chr_file permissive=0

These denials were triggered by the change in
https://android-review.googlesource.com/151209 . Prior to that change,
any code which called klog_init would (unnecessarily) create the
device node themselves, rather than using the already existing device
node.

Drop special /dev/__null__ handling from watchdogd. As of
https://android-review.googlesource.com/148288 , watchdogd no longer
creates it's own /dev/null device, so it's unnecessary for us
to allow for it.

Drop mknod from healthd, slideshow, and watchdogd. healthd and slideshow
only needed mknod to create /dev/__kmsg__, which is now obsolete.
watchdogd only needed mknod to create /dev/__kmsg__ and /dev/__null__,
which again is now obsolete.

Bug: 21242418
Change-Id: If01c8001084575e7441253f0fa8b4179ae33f534

1 files changed, 2 insertions, 2 deletions

diff --git a/slideshow.te b/slideshow.te
index 2b82b3e..86d4bff 100644
--- a/slideshow.te
+++ b/slideshow.te
@@ -2,10 +2,10 @@
 # it lives in the rootfs and has no unique file type.
 type slideshow, domain;
 
-write_klog(slideshow)
+allow slideshow kmsg_device:chr_file rw_file_perms;
 wakelock_use(slideshow)
 allow slideshow device:dir r_dir_perms;
-allow slideshow self:capability { mknod sys_tty_config };
+allow slideshow self:capability sys_tty_config;
 allow slideshow graphics_device:dir r_dir_perms;
 allow slideshow graphics_device:chr_file rw_file_perms;
 allow slideshow input_device:dir r_dir_perms;