app.te

###
### Domain for all zygote spawned apps
###
### This file is the base policy for all zygote spawned apps.
### Other policy files, such as isolated_app.te, untrusted_app.te, etc
### extend from this policy. Only policies which should apply to ALL
### zygote spawned apps should be added here.
###

# Allow apps to connect to the keystore
unix_socket_connect(appdomain, keystore, keystore)

# Receive and use open file descriptors inherited from zygote.
allow appdomain zygote:fd use;

# Read system properties managed by zygote.
allow appdomain zygote_tmpfs:file read;

# Notify zygote of death;
allow appdomain zygote:process sigchld;

# Communicate with system_server.
allow appdomain system:fifo_file rw_file_perms;
allow appdomain system:unix_stream_socket { read write setopt };
binder_call(appdomain, system)

# Communicate with surfaceflinger.
allow appdomain surfaceflinger:unix_stream_socket { read write setopt };
binder_call(appdomain, surfaceflinger)

# App sandbox file accesses.
allow appdomain app_data_file:dir create_dir_perms;
allow appdomain app_data_file:notdevfile_class_set create_file_perms;

# Read/write data files created by the platform apps if they
# were passed to the app via binder or local IPC.  Do not allow open.
allow appdomain platform_app_data_file:file { getattr read write };

# lib subdirectory of /data/data dir is system-owned.
allow appdomain system_data_file:dir r_dir_perms;
allow appdomain system_data_file:file { execute open };

# Execute the shell or other system executables.
allow appdomain shell_exec:file rx_file_perms;
allow appdomain system_file:file rx_file_perms;

# Read/write wallpaper file (opened by system).
allow appdomain wallpaper_file:file { read write };

# Write to /data/anr/traces.txt.
allow appdomain anr_data_file:dir search;
allow appdomain anr_data_file:file { open append };

# Write to /proc/net/xt_qtaguid/ctrl file.
allow appdomain qtaguid_proc:file rw_file_perms;
# Everybody can read the xt_qtaguid resource tracking misc dev.
# So allow all apps to read from /dev/xt_qtaguid.
allow appdomain qtaguid_device:chr_file r_file_perms;

# Use the Binder.
binder_use(appdomain)
# Perform binder IPC to binder services.
binder_call(appdomain, binderservicedomain)
# Perform binder IPC to other apps.
binder_call(appdomain, appdomain)

# Appdomain interaction with isolated apps
r_dir_file(appdomain, isolated_app)
binder_call(appdomain, isolated_app)

# Already connected, unnamed sockets being passed over some other IPC
# hence no sock_file or connectto permission. This appears to be how
# Chrome works, may need to be updated as more apps using isolated services
# are examined.
allow appdomain isolated_app:unix_stream_socket { read write };

# Backup ability for every app. BMS opens and passes the fd
# to any app that has backup ability. Hence, no open permissions here.
allow appdomain backup_data_file:file { read write };
allow appdomain  cache_backup_file:file { read write };
# Backup ability using 'adb backup'
allow appdomain system_data_file:lnk_file getattr;

# Allow all applications to read downloaded files
allow appdomain download_file:file r_file_perms;
file_type_auto_trans(appdomain, download_file, download_file)

# Allow applications to communicate with netd via /dev/socket/dnsproxyd
# to do DNS resolution
unix_socket_connect(appdomain, dnsproxyd, netd)

# Allow applications to communicate with drmserver over binder
binder_call(appdomain, drmserver)

# Allow applications to communicate with mediaserver over binder
binder_call(appdomain, mediaserver)

# Allow applications to make outbound tcp connections to any port
allow appdomain port_type:tcp_socket name_connect;

# Allow apps to see changes to the routing table.
allow appdomain self:netlink_route_socket {
    read
    bind
    create
    nlmsg_read
    ioctl
    getattr
    setattr
    getopt
    setopt
    shutdown
};

# Allow apps to use rawip sockets. This is needed for apps which execute
# /system/bin/ping, for example.
allow appdomain self:rawip_socket create_socket_perms;

###
### Neverallow rules
###
### These are things that Android apps should NEVER be able to do
###

# Superuser capabilities.
# Only exception is sys_nice for binder, might not be necessary.
neverallow { appdomain -unconfineddomain } self:capability ~sys_nice;
neverallow { appdomain -unconfineddomain } self:capability2 *;

# Block device access.
neverallow { appdomain -unconfineddomain } dev_type:blk_file { read write };

# Kernel memory access.
neverallow { appdomain -unconfineddomain } kmem_device:chr_file { read write };

# Setting SELinux enforcing status or booleans.
# Conditionally allowed to system_app for SEAndroidManager.
neverallow { appdomain -unconfineddomain } kernel:security { setenforce setbool };

# Load security policy.
neverallow appdomain kernel:security load_policy;

# Privileged netlink socket interfaces.
neverallow { appdomain -unconfineddomain }
    self:{
        netlink_socket
        netlink_firewall_socket
        netlink_tcpdiag_socket
        netlink_nflog_socket
        netlink_xfrm_socket
        netlink_selinux_socket
        netlink_audit_socket
        netlink_ip6fw_socket
        netlink_dnrt_socket
        netlink_kobject_uevent_socket
    } *;

# ptrace access to non-app domains.
neverallow { appdomain -unconfineddomain } { domain -appdomain }:process ptrace;

# Transition to a non-app domain.
neverallow { appdomain -unconfineddomain } ~appdomain:process { transition dyntransition };

# Write to /system.
neverallow { appdomain -unconfineddomain } system_file:dir_file_class_set write;

# Write to system-owned parts of /data.
# This is the default type for anything under /data not otherwise
# specified in file_contexts.  Define a different type for portions
# that should be writable by apps.
# Exception for system_app for Settings.
neverallow { appdomain -unconfineddomain -system_app } system_data_file:dir_file_class_set write;