platform_system_sepolicy/public/update_engine_common.te

# update_engine payload application permissions. These are shared between the
# background daemon and the recovery tool to sideload an update.

# Allow update_engine to reach block devices in /dev/block.
allow update_engine_common block_device:dir search;

# Allow read/write on system and boot partitions.
allow update_engine_common boot_block_device:blk_file rw_file_perms;
allow update_engine_common system_block_device:blk_file rw_file_perms;

# Where ioctls are granted via standard allow rules to block devices,
# automatically allow common ioctls that are generally needed by
# update_engine.
allowxperm update_engine_common dev_type:blk_file ioctl {
  BLKDISCARD
  BLKDISCARDZEROES
  BLKROGET
  BLKROSET
  BLKSECDISCARD
  BLKZEROOUT
};

# Allow to set recovery options in the BCB. Used to trigger factory reset when
# the update to an older version (channel change) or incompatible version
# requires it.
allow update_engine_common misc_block_device:blk_file rw_file_perms;

# read fstab
allow update_engine_common rootfs:dir getattr;
allow update_engine_common rootfs:file r_file_perms;

# Allow update_engine_common to mount on the /postinstall directory and reset the
# labels on the mounted filesystem to postinstall_file.
allow update_engine_common postinstall_mnt_dir:dir { mounton getattr search };
allow update_engine_common postinstall_file:filesystem { mount unmount relabelfrom relabelto };
allow update_engine_common labeledfs:filesystem relabelfrom;

# Allow update_engine_common to read and execute postinstall_file.
allow update_engine_common postinstall_file:file rx_file_perms;
allow update_engine_common postinstall_file:lnk_file r_file_perms;
allow update_engine_common postinstall_file:dir r_dir_perms;

# install update.zip from cache
r_dir_file(update_engine_common, cache_file)

# A postinstall program is typically a shell script (with a #!), so we allow
# to execute those.
allow update_engine_common shell_exec:file rx_file_perms;

# Allow update_engine_common to suspend, resume and kill the postinstall program.
allow update_engine_common postinstall:process { signal sigstop sigkill };

# access /proc/cmdline
allow update_engine_common proc_cmdline:file r_file_perms;

# Read files in /sys/firmware/devicetree/base/firmware/android/
r_dir_file(update_engine_common, sysfs_dt_firmware_android)

# read / write on /dev/device-mapper to map / unmap devices
allow update_engine_common dm_device:chr_file rw_file_perms;

# apply / verify updates on devices mapped via device mapper
allow update_engine_common dm_device:blk_file rw_file_perms;

# read / write metadata on super device to resize partitions
allow update_engine_common super_block_device:blk_file rw_file_perms;

# ioctl on super device to get block device alignment and alignment offset
allowxperm update_engine_common {
    system_block_device
    super_block_device
}:blk_file ioctl { BLKIOMIN BLKALIGNOFF };

# get physical block device to map logical partitions on device mapper
allow update_engine_common block_device:dir r_dir_perms;