platform_system_sepolicy/blkid_untrusted.te

# blkid for untrusted block devices
type blkid_untrusted, domain, domain_deprecated;

# Allowed read-only access to vold block devices to extract UUID/label
allow blkid_untrusted block_device:dir search;
allow blkid_untrusted vold_device:blk_file r_file_perms;

# Allow stdin/out back to vold
allow blkid_untrusted vold:fd use;
allow blkid_untrusted vold:fifo_file { read write getattr };

# For blkid launched through popen()
allow blkid_untrusted blkid_exec:file rx_file_perms;

###
### neverallow rules
###

# Untrusted blkid should never be run on block devices holding sensitive data
neverallow blkid_untrusted {
  boot_block_device
  frp_block_device
  metadata_block_device
  recovery_block_device
  root_block_device
  swap_block_device
  system_block_device
  userdata_block_device
  cache_block_device
  dm_device
}:blk_file no_rw_file_perms;

# Only allow entry from vold via blkid binary
neverallow { domain -vold } blkid_untrusted:process transition;
neverallow * blkid_untrusted:process dyntransition;
neverallow blkid_untrusted { file_type fs_type -blkid_exec -shell_exec }:file entrypoint;