sepolicy/private/netd.te

typeattribute netd coredomain;
typeattribute netd bpfdomain;

init_daemon_domain(netd)

# Allow netd to spawn dnsmasq in it's own domain
domain_auto_trans(netd, dnsmasq_exec, dnsmasq)

allow netd { fs_bpf fs_bpf_netd_readonly fs_bpf_netd_shared fs_bpf_vendor }:dir search;
allow netd { fs_bpf fs_bpf_netd_readonly fs_bpf_netd_shared fs_bpf_vendor }:file { getattr read };
allow netd { fs_bpf                      fs_bpf_netd_shared               }:file write;

# give netd permission to setup iptables rule with xt_bpf, attach program to cgroup,
# create maps, and read/write maps created by bpfloader, itself and NS/SS mainline networking
allow netd bpfloader:bpf prog_run;
allow netd self:bpf map_create;
allow netd { bpfloader netd network_stack system_server }:bpf { map_read map_write };

# in order to invoke side effect of close() on such a socket calling synchronize_rcu()
# TODO: Still needed as of kernel 6.6-rc1 - see BpfUtils.h synchronizeKernelRCU()
# TODO: Remove this after we remove all bpf interactions from netd.
allow netd self:key_socket create;

set_prop(netd, ctl_mdnsd_prop)
set_prop(netd, netd_stable_secret_prop)

get_prop(netd, adbd_config_prop)
get_prop(netd, hwservicemanager_prop)
get_prop(netd, device_config_netd_native_prop)

# Allow netd to write to statsd.
unix_socket_send(netd, statsdw, statsd)

# Allow netd to send callbacks to network_stack
binder_call(netd, network_stack)

# Allow netd to send dump info to dumpstate
allow netd dumpstate:fd use;
allow netd dumpstate:fifo_file { getattr write };

net_domain(netd)
# Connect to mdnsd via mdnsd socket.
unix_socket_connect(netd, mdnsd, mdnsd)
# in addition to ioctls allowlisted for all domains, grant netd priv_sock_ioctls.
allowxperm netd self:udp_socket ioctl priv_sock_ioctls;

r_dir_file(netd, cgroup)

allow netd system_server:fd use;

allow netd self:global_capability_class_set { net_admin net_raw kill };
# Note: fsetid is deliberately not included above. fsetid checks are
# triggered by chmod on a directory or file owned by a group other
# than one of the groups assigned to the current process to see if
# the setgid bit should be cleared, regardless of whether the setgid
# bit was even set.  We do not appear to truly need this capability
# for netd to operate.
dontaudit netd self:global_capability_class_set fsetid;

# Allow netd to open /dev/tun, set it up and pass it to clatd
allow netd tun_device:chr_file rw_file_perms;
allowxperm netd tun_device:chr_file ioctl { TUNGETIFF TUNSETIFF };
allow netd self:tun_socket create;

allow netd self:netlink_kobject_uevent_socket create_socket_perms_no_ioctl;
allow netd self:netlink_route_socket nlmsg_write;
allow netd self:netlink_nflog_socket create_socket_perms_no_ioctl;
allow netd self:netlink_socket create_socket_perms_no_ioctl;
allow netd self:netlink_tcpdiag_socket { create_socket_perms_no_ioctl nlmsg_read nlmsg_write };
allow netd self:netlink_generic_socket create_socket_perms_no_ioctl;
allow netd self:netlink_netfilter_socket create_socket_perms_no_ioctl;
allow netd shell_exec:file rx_file_perms;
allow netd system_file:file x_file_perms;
not_full_treble(`allow netd vendor_file:file x_file_perms;')
allow netd devpts:chr_file rw_file_perms;

# Acquire advisory lock on /system/etc/xtables.lock. If this file doesn't
# exist, suppress the denial.
allow netd system_file:file lock;
dontaudit netd system_file:dir write;

r_dir_file(netd, proc_net_type)
# For /proc/sys/net/ipv[46]/route/flush.
allow netd proc_net_type:file rw_file_perms;

# Enables PppController and interface enumeration (among others)
allow netd sysfs:dir r_dir_perms;
r_dir_file(netd, sysfs_net)

# Allows setting interface MTU
allow netd sysfs_net:file w_file_perms;

# TODO: added to match above sysfs rule. Remove me?
allow netd sysfs_usb:file write;

r_dir_file(netd, cgroup_v2)

# TODO: netd previously thought it needed these permissions to do WiFi related
#       work.  However, after all the WiFi stuff is gone, we still need them.
#       Why?
allow netd self:global_capability_class_set { dac_override dac_read_search chown };

# Needed to update /data/misc/net/rt_tables
allow netd net_data_file:file create_file_perms;
allow netd net_data_file:dir rw_dir_perms;
allow netd self:global_capability_class_set fowner;

# Needed to lock the iptables lock.
allow netd system_file:file lock;

# Allow netd to spawn dnsmasq in it's own domain
allow netd dnsmasq:process { sigkill signal };

# Allow netd to publish a binder service and make binder calls.
binder_use(netd)
add_service(netd, netd_service)
add_service(netd, dnsresolver_service)
add_service(netd, mdns_service)
allow netd dumpstate:fifo_file  { getattr write };

# Allow netd to call into the system server so it can check permissions.
allow netd system_server:binder call;
allow netd permission_service:service_manager find;

# Allow netd to talk to the framework service which collects netd events.
allow netd netd_listener_service:service_manager find;

# Allow netd to operate on sockets that are passed to it.
allow netd netdomain:{
  icmp_socket
  tcp_socket
  udp_socket
  rawip_socket
  tun_socket
} { read write getattr setattr getopt setopt };
allow netd netdomain:fd use;

# give netd permission to read and write netlink xfrm
allow netd self:netlink_xfrm_socket { create_socket_perms_no_ioctl nlmsg_write nlmsg_read };

# Allow netd to register as hal server.
add_hwservice(netd, system_net_netd_hwservice)
hwbinder_use(netd)

# AIDL hal server
binder_call(system_net_netd_service, servicemanager)
add_service(netd, system_net_netd_service)

###
### Neverallow rules
###
### netd should NEVER do any of this

# Block device access.
neverallow netd dev_type:blk_file { read write };

# ptrace any other app
neverallow netd { domain }:process ptrace;

# Write to /system.
neverallow netd system_file_type:dir_file_class_set write;

# Write to files in /data/data or system files on /data
neverallow netd { app_data_file_type system_data_file }:dir_file_class_set write;

# only system_server, dumpstate and network stack app may find netd service
neverallow {
    domain
    -system_server
    -dumpstate
    -network_stack
    -netd
    -netutils_wrapper
} netd_service:service_manager find;

# only system_server, dumpstate and network stack app may find dnsresolver service
neverallow {
    domain
    -system_server
    -dumpstate
    -network_stack
    -netd
    -netutils_wrapper
} dnsresolver_service:service_manager find;

# only system_server, dumpstate and network stack app may find mdns service
neverallow {
    domain
    -system_server
    -dumpstate
    -network_stack
    -netd
    -netutils_wrapper
} mdns_service:service_manager find;

# apps may not interact with netd over binder.
neverallow { appdomain -network_stack } netd:binder call;
neverallow netd { appdomain -network_stack userdebug_or_eng(`-su') }:binder call;

# If an already existing file is opened with O_CREATE, the kernel might generate
# a false report of a create denial. Silence these denials and make sure that
# inappropriate permissions are not granted.
neverallow netd proc_net:dir no_w_dir_perms;
dontaudit netd proc_net:dir write;

neverallow netd sysfs_net:dir no_w_dir_perms;
dontaudit netd sysfs_net:dir write;

# Netd should not have SYS_ADMIN privs.
neverallow netd self:capability sys_admin;
dontaudit netd self:capability sys_admin;

# Netd should not have SYS_MODULE privs, nor should it be requesting module loads
# (things it requires should be built directly into the kernel)
dontaudit netd self:capability sys_module;

dontaudit netd appdomain:unix_stream_socket { read write };

# persist.netd.stable_secret contains RFC 7217 secret key which should never be
# leaked to other processes. Make sure it never leaks.
neverallow { domain -netd -init -dumpstate } netd_stable_secret_prop:file r_file_perms;

# We want to ensure that no other process ever tries tampering with persist.netd.stable_secret,
# the RFC 7217 secret key managed by netd. Doing so could compromise user privacy.
neverallow { domain -netd -init } netd_stable_secret_prop:property_service set;