| ### |
| ### neverallow rules for untrusted app domains |
| ### |
| |
| define(`all_untrusted_apps',`{ |
| ephemeral_app |
| isolated_app |
| isolated_app_all |
| isolated_compute_app |
| mediaprovider |
| mediaprovider_app |
| untrusted_app |
| untrusted_app_25 |
| untrusted_app_27 |
| untrusted_app_29 |
| untrusted_app_30 |
| untrusted_app_all |
| }') |
| # Receive or send uevent messages. |
| neverallow all_untrusted_apps domain:netlink_kobject_uevent_socket *; |
| |
| # Receive or send generic netlink messages |
| neverallow all_untrusted_apps domain:netlink_socket *; |
| |
| # Read or write kernel printk buffer |
| neverallow all_untrusted_apps kmsg_device:chr_file no_rw_file_perms; |
| |
| # Too much leaky information in debugfs. It's a security |
| # best practice to ensure these files aren't readable. |
| neverallow all_untrusted_apps { debugfs_type -debugfs_kcov }:file read; |
| neverallow {all_untrusted_apps userdebug_or_eng(`-domain')} debugfs_type:{ file lnk_file } read; |
| |
| # Do not allow untrusted apps to register services. |
| # Only trusted components of Android should be registering |
| # services. |
| neverallow all_untrusted_apps service_manager_type:service_manager add; |
| |
| # Do not allow untrusted apps to use VendorBinder |
| neverallow all_untrusted_apps vndbinder_device:chr_file *; |
| neverallow all_untrusted_apps vndservice_manager_type:service_manager *; |
| |
| # Do not allow untrusted apps to connect to the property service |
| # or set properties. b/10243159 |
| neverallow { all_untrusted_apps -mediaprovider } property_socket:sock_file write; |
| neverallow { all_untrusted_apps -mediaprovider } init:unix_stream_socket connectto; |
| neverallow { all_untrusted_apps -mediaprovider } property_type:property_service set; |
| |
| # net.dns properties are not a public API. Disallow untrusted apps from reading this property. |
| neverallow { all_untrusted_apps } net_dns_prop:file read; |
| |
| # radio_cdma_ecm_prop properties are not a public API. Disallow untrusted apps from reading this property. |
| neverallow { all_untrusted_apps } radio_cdma_ecm_prop:file read; |
| |
| # Shared libraries created by trusted components within an app home |
| # directory can be dlopen()ed. To maintain the W^X property, these files |
| # must never be writable to the app. |
| neverallow all_untrusted_apps app_exec_data_file:file |
| { append create link relabelfrom relabelto rename setattr write }; |
| |
| # Block calling execve() on files in an apps home directory. |
| # This is a W^X violation (loading executable code from a writable |
| # home directory). For compatibility, allow for targetApi <= 28. |
| # b/112357170 |
| neverallow { |
| all_untrusted_apps |
| -untrusted_app_25 |
| -untrusted_app_27 |
| -runas_app |
| } { app_data_file privapp_data_file }:file execute_no_trans; |
| |
| # Do not allow untrusted apps to invoke dex2oat. This was historically required |
| # by ART for compiling secondary dex files but has been removed in Q. |
| # Exempt legacy apps (targetApi<=28) for compatibility. |
| neverallow { |
| all_untrusted_apps |
| -untrusted_app_25 |
| -untrusted_app_27 |
| } dex2oat_exec:file no_x_file_perms; |
| |
| # Do not allow untrusted apps to be assigned mlstrustedsubject. |
| # This would undermine the per-user isolation model being |
| # enforced via levelFrom=user in seapp_contexts and the mls |
| # constraints. As there is no direct way to specify a neverallow |
| # on attribute assignment, this relies on the fact that fork |
| # permission only makes sense within a domain (hence should |
| # never be granted to any other domain within mlstrustedsubject) |
| # and an untrusted app is allowed fork permission to itself. |
| neverallow all_untrusted_apps mlstrustedsubject:process fork; |
| |
| # Do not allow untrusted apps to hard link to any files. |
| # In particular, if an untrusted app links to other app data |
| # files, installd will not be able to guarantee the deletion |
| # of the linked to file. Hard links also contribute to security |
| # bugs, so we want to ensure untrusted apps never have this |
| # capability. |
| neverallow all_untrusted_apps file_type:file link; |
| |
| # Do not allow untrusted apps to access network MAC address file |
| neverallow all_untrusted_apps sysfs_net:file no_rw_file_perms; |
| |
| # Do not allow any write access to files in /sys |
| neverallow all_untrusted_apps sysfs_type:file { no_w_file_perms no_x_file_perms }; |
| |
| # Apps may never access the default sysfs label. |
| neverallow all_untrusted_apps sysfs:file no_rw_file_perms; |
| |
| # Restrict socket ioctls. Either 1. disallow privileged ioctls, 2. disallow the |
| # ioctl permission, or 3. disallow the socket class. |
| neverallowxperm all_untrusted_apps domain:{ icmp_socket rawip_socket tcp_socket udp_socket } ioctl priv_sock_ioctls; |
| neverallow all_untrusted_apps *:{ netlink_route_socket netlink_selinux_socket } ioctl; |
| neverallow all_untrusted_apps *:{ |
| socket netlink_socket packet_socket key_socket appletalk_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 |
| 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 kcm_socket qipcrtr_socket smc_socket xdp_socket |
| } *; |
| |
| # Apps can read/write an already open vsock (e.g. created by |
| # virtualizationservice) but nothing more than that (e.g. creating a |
| # new vsock, etc.) |
| neverallow all_untrusted_apps *:vsock_socket ~{ getattr getopt read write }; |
| |
| # Disallow sending RTM_GETLINK messages on netlink sockets. |
| neverallow all_untrusted_apps domain:netlink_route_socket { bind nlmsg_readpriv }; |
| neverallow priv_app domain:netlink_route_socket { bind nlmsg_readpriv }; |
| |
| # Disallow sending RTM_GETNEIGH{TBL} messages on netlink sockets. |
| neverallow { |
| all_untrusted_apps |
| -untrusted_app_25 |
| -untrusted_app_27 |
| -untrusted_app_29 |
| -untrusted_app_30 |
| } domain:netlink_route_socket nlmsg_getneigh; |
| |
| # Do not allow untrusted apps access to /cache |
| neverallow { all_untrusted_apps -mediaprovider } { cache_file cache_recovery_file }:dir ~{ r_dir_perms }; |
| neverallow { all_untrusted_apps -mediaprovider } { cache_file cache_recovery_file }:file ~{ read getattr }; |
| |
| # Do not allow untrusted apps to create/unlink files outside of its sandbox, |
| # internal storage or sdcard. |
| # World accessible data locations allow application to fill the device |
| # with unaccounted for data. This data will not get removed during |
| # application un-installation. |
| neverallow { all_untrusted_apps -mediaprovider } { |
| fs_type |
| -sdcard_type |
| -fuse |
| file_type |
| -app_data_file # The apps sandbox itself |
| -privapp_data_file |
| -app_exec_data_file # stored within the app sandbox directory |
| -media_rw_data_file # Internal storage. Known that apps can |
| # leave artfacts here after uninstall. |
| -user_profile_data_file # Access to profile files |
| userdebug_or_eng(` |
| -method_trace_data_file # only on ro.debuggable=1 |
| -coredump_file # userdebug/eng only |
| ') |
| }:dir_file_class_set { create unlink }; |
| |
| # No untrusted component except mediaprovider_app should be touching /dev/fuse |
| neverallow { all_untrusted_apps -mediaprovider_app } fuse_device:chr_file *; |
| |
| # Do not allow untrusted apps to directly open the tun_device |
| neverallow all_untrusted_apps tun_device:chr_file open; |
| # The tun_device ioctls below are not allowed, to prove equivalence |
| # to the kernel patch at |
| # https://android.googlesource.com/kernel/common/+/11cee2be0c2062ba88f04eb51196506f870a3b5d%5E%21 |
| neverallowxperm all_untrusted_apps tun_device:chr_file ioctl ~{ FIOCLEX FIONCLEX TUNGETIFF }; |
| |
| # Only allow appending to /data/anr/traces.txt (b/27853304, b/18340553) |
| neverallow all_untrusted_apps anr_data_file:file ~{ open append }; |
| neverallow all_untrusted_apps anr_data_file:dir ~search; |
| |
| # Avoid reads from generically labeled /proc files |
| # Create a more specific label if needed |
| neverallow all_untrusted_apps { |
| proc |
| proc_asound |
| proc_kmsg |
| proc_loadavg |
| proc_mounts |
| proc_pagetypeinfo |
| proc_slabinfo |
| proc_stat |
| proc_swaps |
| proc_uptime |
| proc_version |
| proc_vmallocinfo |
| proc_vmstat |
| }:file { no_rw_file_perms no_x_file_perms }; |
| |
| # /proc/filesystems is accessible to mediaprovider_app only since it handles |
| # external storage |
| neverallow { all_untrusted_apps - mediaprovider_app } proc_filesystems:file { no_rw_file_perms no_x_file_perms }; |
| |
| # Avoid all access to kernel configuration |
| neverallow all_untrusted_apps config_gz:file { no_rw_file_perms no_x_file_perms }; |
| |
| # Do not allow untrusted apps access to preloads data files |
| neverallow all_untrusted_apps preloads_data_file:file no_rw_file_perms; |
| |
| # Locking of files on /system could lead to denial of service attacks |
| # against privileged system components |
| neverallow all_untrusted_apps system_file:file lock; |
| |
| # Do not permit untrusted apps to perform actions on HwBinder service_manager |
| # other than find actions for services listed below |
| neverallow all_untrusted_apps *:hwservice_manager ~find; |
| |
| # Do not permit access from apps which host arbitrary code to the protected services |
| # The two main reasons for this are: |
| # 1. Protected HwBinder servers do not perform client authentication because |
| # vendor code does not have a way to understand apps or their relation to |
| # caller UID information and, even if it did, those services either operate |
| # at a level below that of apps (e.g., HALs) or must not rely on app identity |
| # for authorization. Thus, to be safe, the default assumption for all added |
| # vendor services is that they treat all their clients as equally authorized |
| # to perform operations offered by the service. |
| # 2. HAL servers contain code with higher incidence rate of security issues |
| # than system/core components and have access to lower layes of the stack |
| # (all the way down to hardware) thus increasing opportunities for bypassing |
| # the Android security model. |
| neverallow all_untrusted_apps protected_hwservice:hwservice_manager find; |
| neverallow all_untrusted_apps protected_service:service_manager find; |
| |
| # SELinux is not an API for untrusted apps to use |
| neverallow all_untrusted_apps selinuxfs:file no_rw_file_perms; |
| |
| # Access to /proc/tty/drivers, to allow apps to determine if they |
| # are running in an emulated environment. |
| # b/33214085 b/33814662 b/33791054 b/33211769 |
| # https://github.com/strazzere/anti-emulator/blob/master/AntiEmulator/src/diff/strazzere/anti/emulator/FindEmulator.java |
| # This will go away in a future Android release |
| neverallow { all_untrusted_apps -untrusted_app_25 } proc_tty_drivers:file r_file_perms; |
| neverallow all_untrusted_apps proc_tty_drivers:file ~r_file_perms; |
| |
| # Untrusted apps are not allowed to use cgroups. |
| neverallow all_untrusted_apps cgroup:file *; |
| neverallow all_untrusted_apps cgroup_v2:file *; |
| |
| # /mnt/sdcard symlink was supposed to have been removed in Gingerbread. Apps |
| # must not use it. |
| neverallow { |
| all_untrusted_apps |
| -untrusted_app_25 |
| -untrusted_app_27 |
| } mnt_sdcard_file:lnk_file *; |
| |
| # Only privileged apps may find the incident service |
| neverallow all_untrusted_apps incident_service:service_manager find; |
| |
| # Do not allow untrusted app to read hidden system proprerties. |
| # We do not include in the exclusions other normally untrusted applications such as mediaprovider |
| # due to the specific logging use cases. |
| # Context: b/193912100 |
| neverallow { |
| all_untrusted_apps |
| -mediaprovider |
| -mediaprovider_app |
| } { userdebug_or_eng_prop }:file read; |
| |
| # Do not allow untrusted app to access /dev/socket/mdnsd since U. The socket is |
| # used to communicate to the mdnsd responder. The mdnsd responder will be |
| # replaced by a java implementation which is integrated into the system server. |
| # For untrusted apps running with API level 33-, they still have access to |
| # /dev/socket/mdnsd for backward compatibility. |
| neverallow { |
| all_untrusted_apps |
| -untrusted_app_25 |
| -untrusted_app_27 |
| -untrusted_app_29 |
| -untrusted_app_30 |
| -untrusted_app_32 |
| } mdnsd_socket:sock_file write; |
| neverallow { |
| all_untrusted_apps |
| -untrusted_app_25 |
| -untrusted_app_27 |
| -untrusted_app_29 |
| -untrusted_app_30 |
| -untrusted_app_32 |
| } mdnsd:unix_stream_socket connectto; |
| |
| # Do not allow untrusted apps to use anonymous inodes. At the moment, |
| # type transitions are the only way to distinguish between different |
| # anon_inode usages like userfaultfd and io_uring. This prevents us from |
| # creating a more fine-grained neverallow policy for each anon_inode usage. |
| neverallow all_untrusted_apps domain:anon_inode *; |