update_engine_common.te

Address the "granted" permissions observed in the logs including:

tcontext=uncrypt
avc: granted { search } for comm="uncrypt" name="/" dev="mmcblk0p40"
ino=2 scontext=u:r:uncrypt:s0 tcontext=u:object_r:cache_file:s0
tclass=dir

tcontext=install_recovery
avc: granted { search } for comm="applypatch" name="saved.file"
scontext=u:r:install_recovery:s0 tcontext=u:object_r:cache_file:s0
tclass=dir
avc: granted { read } for comm="applypatch" name="saved.file"
dev="mmcblk0p6" ino=14 scontext=u:r:install_recovery:s0
tcontext=u:object_r:cache_file:s0 tclass=file
avc: granted { getattr } for comm="applypatch" path="/cache/saved.file"
dev="mmcblk0p6" ino=14 scontext=u:r:install_recovery:s0
tcontext=u:object_r:cache_file:s0 tclass=file

tcontext=update_engine
avc: granted { search } for comm="update_engine" name="cache"
dev="sda35" ino=1409025 scontext=u:r:update_engine:s0
tcontext=u:object_r:cache_file:s0 tclass=dir"
avc: granted { read } for comm="update_engine" name="update.zip"
dev="sda35" ino=1409037 scontext=u:r:update_engine:s0
tcontext=u:object_r:cache_file:s0:c512,c768 tclass=file
avc: granted { read } for comm="update_engine" name="cache" dev="dm-0"
ino=16 scontext=u:r:update_engine:s0 tcontext=u:object_r:cache_file:s0
tclass=lnk_file

Bug: 28760354
Test: build policy.
Merged-In: Ia13fe47268df904bd4f815c429a0acac961aed1e
Change-Id: Ia13fe47268df904bd4f815c429a0acac961aed1e