private/webview_zygote.te

# webview_zygote is an auxiliary zygote process that is used to spawn
# isolated_app processes for rendering untrusted web content.

typeattribute webview_zygote coredomain;

# The webview_zygote needs to be able to transition domains.
typeattribute webview_zygote mlstrustedsubject;

# Allow access to temporary files, which is normally permitted through
# a domain macro.
tmpfs_domain(webview_zygote);

userfaultfd_use(webview_zygote)

# Allow reading/executing installed binaries to enable preloading the
# installed WebView implementation.
allow webview_zygote apk_data_file:dir r_dir_perms;
allow webview_zygote apk_data_file:file { r_file_perms execute };

# Access to the WebView relro file.
allow webview_zygote shared_relro_file:dir search;
allow webview_zygote shared_relro_file:file r_file_perms;

# Set the UID/GID of the process.
allow webview_zygote self:global_capability_class_set { setgid setuid };
# Drop capabilities from bounding set.
allow webview_zygote self:global_capability_class_set setpcap;
# Switch SELinux context to app domains.
allow webview_zygote self:process setcurrent;
allow webview_zygote isolated_app:process dyntransition;

# For art.
allow webview_zygote { apex_art_data_file dalvikcache_data_file }:dir r_dir_perms;
allow webview_zygote dalvikcache_data_file:lnk_file r_file_perms;
allow webview_zygote { apex_art_data_file dalvikcache_data_file }:file { r_file_perms execute };
allow webview_zygote apex_module_data_file:dir search;

# Allow webview_zygote to create JIT memory.
allow webview_zygote self:process execmem;

# Allow webview_zygote to stat the files that it opens. It must
# be able to inspect them so that it can reopen them on fork
# if necessary: b/30963384.
allow webview_zygote debugfs_trace_marker:file getattr;

# Allow webview_zygote to manage the pgroup of its children.
allow webview_zygote system_server:process getpgid;

# Interaction between the webview_zygote and its children.
allow webview_zygote isolated_app:process setpgid;

# TODO (b/63631799) fix this access
# Suppress denials to storage. Webview zygote should not be accessing.
dontaudit webview_zygote mnt_expand_file:dir getattr;

# TODO (b/72957399) remove this when webview_zygote is reparented to
# app_process zygote
dontaudit webview_zygote dex2oat_exec:file execute;

# Get seapp_contexts
allow webview_zygote seapp_contexts_file:file r_file_perms;
# Check validity of SELinux context before use.
selinux_check_context(webview_zygote)
# Check SELinux permissions.
selinux_check_access(webview_zygote)

# Directory listing in /system.
allow webview_zygote system_file:dir r_dir_perms;

# Read and inspect temporary files (like system properties) managed by zygote.
allow webview_zygote zygote_tmpfs:file { read getattr };
# Child of zygote.
allow webview_zygote zygote:fd use;
allow webview_zygote zygote:process sigchld;

# Allow apps access to /vendor/overlay
r_dir_file(webview_zygote, vendor_overlay_file)

allow webview_zygote same_process_hal_file:file { execute read open getattr map };

allow webview_zygote system_data_file:lnk_file r_file_perms;

# Send unsolicited message to system_server
unix_socket_send(webview_zygote, system_unsolzygote, system_server)

# Allow the webview_zygote to access the runtime feature flag properties.
get_prop(webview_zygote, device_config_runtime_native_prop)
get_prop(webview_zygote, device_config_runtime_native_boot_prop)

# Allow webview_zygote to access odsign verification status
get_prop(zygote, odsign_prop)

#####
##### Neverallow
#####

# Only permit transition to isolated_app.
neverallow webview_zygote { domain -isolated_app }:process dyntransition;

# Only setcon() transitions, no exec() based transitions, except for crash_dump.
neverallow webview_zygote { domain -crash_dump }:process transition;

# Must not exec() a program without changing domains.
# Having said that, exec() above is not allowed.
neverallow webview_zygote *:file execute_no_trans;

# The only way to enter this domain is for the zygote to fork a new
# webview_zygote child.
neverallow { domain -zygote } webview_zygote:process dyntransition;

# Disallow write access to properties.
neverallow webview_zygote property_socket:sock_file write;
neverallow webview_zygote property_type:property_service set;

# Should not have any access to app data files.
neverallow webview_zygote app_data_file_type:file { rwx_file_perms };

neverallow webview_zygote {
    service_manager_type
    -activity_service
    -webviewupdate_service
}:service_manager find;

# Isolated apps shouldn't be able to access the driver directly.
neverallow webview_zygote gpu_device:chr_file { rwx_file_perms };

# Do not allow webview_zygote access to /cache.
neverallow webview_zygote cache_file:dir ~{ r_dir_perms };
neverallow webview_zygote cache_file:file ~{ read getattr };

# Do not allow most socket access. This is socket_class_set, excluding unix_dgram_socket,
# unix_stream_socket, and netlink_selinux_socket.
neverallow webview_zygote domain:{
  socket tcp_socket udp_socket rawip_socket netlink_socket packet_socket key_socket
  appletalk_socket netlink_route_socket netlink_tcpdiag_socket
  netlink_nflog_socket netlink_xfrm_socket netlink_audit_socket
  netlink_dnrt_socket netlink_kobject_uevent_socket tun_socket netlink_iscsi_socket
  netlink_fib_lookup_socket netlink_connector_socket netlink_netfilter_socket
  netlink_generic_socket netlink_scsitransport_socket netlink_rdma_socket netlink_crypto_socket
  sctp_socket icmp_socket ax25_socket ipx_socket netrom_socket atmpvc_socket
  x25_socket rose_socket decnet_socket atmsvc_socket rds_socket irda_socket
  pppox_socket llc_socket can_socket tipc_socket bluetooth_socket iucv_socket
  rxrpc_socket isdn_socket phonet_socket ieee802154_socket caif_socket
  alg_socket nfc_socket vsock_socket kcm_socket qipcrtr_socket smc_socket
  xdp_socket
} *;

# Do not allow access to Bluetooth-related system properties.
# neverallow rules for Bluetooth-related data files are listed above.
neverallow webview_zygote {
  bluetooth_a2dp_offload_prop
  bluetooth_audio_hal_prop
  bluetooth_prop
  exported_bluetooth_prop
}:file create_file_perms;