platform_system_sepolicy/private/snapuserd.te

# snapuserd - Daemon for servicing dm-user requests for Virtual A/B snapshots.
type snapuserd, domain;
type snapuserd_exec, exec_type, file_type, system_file_type;

typeattribute snapuserd coredomain;

init_daemon_domain(snapuserd)

allow snapuserd kmsg_device:chr_file rw_file_perms;

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

# Read /sys/block to find all the DM directories like (/sys/block/dm-X).
allow snapuserd sysfs:dir { open read };

# Read /sys/block/dm-X/dm/name (which is a symlink to
# /sys/devices/virtual/block/dm-X/dm/name) to identify the mapping between
# dm-X and dynamic partitions.
allow snapuserd sysfs_dm:dir { open read search };
allow snapuserd sysfs_dm:file r_file_perms;

# Reading and writing to /dev/block/dm-* (device-mapper) nodes.
allow snapuserd block_device:dir r_dir_perms;
allow snapuserd dm_device:chr_file rw_file_perms;
allow snapuserd dm_device:blk_file rw_file_perms;

# Reading and writing to dm-user control nodes.
allow snapuserd dm_user_device:dir r_dir_perms;
allow snapuserd dm_user_device:chr_file rw_file_perms;

# Reading and writing to /dev/socket/snapuserd and snapuserd_proxy.
allow snapuserd snapuserd_socket:unix_stream_socket { accept listen getattr read write };
allow snapuserd snapuserd_proxy_socket:sock_file write;

# This arises due to first-stage init opening /dev/null without F_CLOEXEC
# (see SetStdioToDevNull in init). When we fork() and execveat() snapuserd
# again, the descriptor leaks into the new process.
allow snapuserd kernel:fd use;

# snapuserd.* properties
set_prop(snapuserd, snapuserd_prop)
get_prop(snapuserd, virtual_ab_prop)

# For inotify watching for /dev/socket/snapuserd_proxy to appear.
allow snapuserd tmpfs:dir { read watch };

# Forbid anything other than snapuserd and init setting snapuserd properties.
neverallow {
  domain
  -snapuserd
  -init
} snapuserd_prop:property_service set;

# Allow to read/write/create OTA metadata files
allow snapuserd metadata_file:dir search;
allow snapuserd ota_metadata_file:dir rw_dir_perms;
allow snapuserd ota_metadata_file:file create_file_perms;

# This capability allows snapuserd to circumvent memlock rlimits while using
# io_uring. An Alternative would be to up the memlock rlimit for the snapuserd service.
allow snapuserd self:capability ipc_lock;
io_uring_use(snapuserd)