bacb6d7936
Motivation: Provide the ability to phase in new security policies by applying them to apps with a minimum targetSdkVersion. Place untrusted apps with targetSdkVersion<=25 into the untrustd_app_25 domain. Apps with targetSdkVersion>=26 are placed into the untrusted_app domain. Common rules are included in the untrusted_app_all attribute. Apps with a more recent targetSdkVersion are granted fewer permissions. Test: Marlin builds and boots. Apps targeting targetSdkVersion<=25 run in untrusted_app_25 domain. Apps targeting the current development build >=26 run in the untrusted_app domain with fewer permissions. No new denials observed during testing. Bug: 34115651 Bug: 35323421 Change-Id: Ie6a015566fac07c44ea06c963c40793fcdc9a083
103 lines
5.2 KiB
Text
103 lines
5.2 KiB
Text
###
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### neverallow rules for untrusted app domains
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###
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# Only allow domains in AOSP to use the untrusted_app_all attribute.
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neverallow { untrusted_app_all -untrusted_app -untrusted_app_25 } domain:process fork;
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# Receive or send uevent messages.
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neverallow { untrusted_app_all ephemeral_app isolated_app } domain:netlink_kobject_uevent_socket *;
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# Receive or send generic netlink messages
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neverallow { untrusted_app_all ephemeral_app isolated_app } domain:netlink_socket *;
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# Too much leaky information in debugfs. It's a security
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# best practice to ensure these files aren't readable.
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neverallow { untrusted_app_all ephemeral_app isolated_app } debugfs_type:file read;
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# Do not allow untrusted apps to register services.
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# Only trusted components of Android should be registering
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# services.
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neverallow { untrusted_app_all ephemeral_app isolated_app } service_manager_type:service_manager add;
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# Do not allow untrusted apps to connect to the property service
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# or set properties. b/10243159
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neverallow { untrusted_app_all ephemeral_app isolated_app } property_socket:sock_file write;
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neverallow { untrusted_app_all ephemeral_app isolated_app } init:unix_stream_socket connectto;
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neverallow { untrusted_app_all ephemeral_app isolated_app } property_type:property_service set;
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# b/34115651 - net.dns* properties read
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# This will go away in a future Android release
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neverallow { appdomain -untrusted_app_25 } net_dns_prop:file r_file_perms;
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# Do not allow untrusted apps to be assigned mlstrustedsubject.
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# This would undermine the per-user isolation model being
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# enforced via levelFrom=user in seapp_contexts and the mls
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# constraints. As there is no direct way to specify a neverallow
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# on attribute assignment, this relies on the fact that fork
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# permission only makes sense within a domain (hence should
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# never be granted to any other domain within mlstrustedsubject)
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# and an untrusted app is allowed fork permission to itself.
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neverallow { untrusted_app_all ephemeral_app isolated_app } mlstrustedsubject:process fork;
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# Do not allow untrusted apps to hard link to any files.
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# In particular, if an untrusted app links to other app data
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# files, installd will not be able to guarantee the deletion
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# of the linked to file. Hard links also contribute to security
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# bugs, so we want to ensure untrusted apps never have this
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# capability.
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neverallow { untrusted_app_all ephemeral_app isolated_app } file_type:file link;
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# Do not allow untrusted apps to access network MAC address file
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neverallow { untrusted_app_all ephemeral_app isolated_app } sysfs_mac_address:file no_rw_file_perms;
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# Restrict socket ioctls. Either 1. disallow privileged ioctls, 2. disallow the
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# ioctl permission, or 3. disallow the socket class.
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neverallowxperm { untrusted_app_all ephemeral_app isolated_app } domain:{ rawip_socket tcp_socket udp_socket } ioctl priv_sock_ioctls;
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neverallow { untrusted_app_all ephemeral_app isolated_app } *:{ netlink_route_socket netlink_selinux_socket } ioctl;
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neverallow { untrusted_app_all ephemeral_app isolated_app } *:{
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socket netlink_socket packet_socket key_socket appletalk_socket
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netlink_tcpdiag_socket netlink_nflog_socket
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netlink_xfrm_socket netlink_audit_socket
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netlink_dnrt_socket netlink_kobject_uevent_socket tun_socket
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netlink_iscsi_socket netlink_fib_lookup_socket netlink_connector_socket
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netlink_netfilter_socket netlink_generic_socket netlink_scsitransport_socket
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netlink_rdma_socket netlink_crypto_socket
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} *;
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# Do not allow untrusted apps access to /cache
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neverallow { untrusted_app_all ephemeral_app isolated_app } { cache_file cache_recovery_file }:dir ~{ r_dir_perms };
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neverallow { untrusted_app_all ephemeral_app isolated_app } { cache_file cache_recovery_file }:file ~{ read getattr };
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# Do not allow untrusted apps to create/unlink files outside of its sandbox,
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# internal storage or sdcard.
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# World accessible data locations allow application to fill the device
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# with unaccounted for data. This data will not get removed during
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# application un-installation.
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neverallow { untrusted_app_all ephemeral_app isolated_app } {
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fs_type
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-fuse # sdcard
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-sdcardfs # sdcard
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-vfat
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file_type
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-app_data_file # The apps sandbox itself
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-media_rw_data_file # Internal storage. Known that apps can
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# leave artfacts here after uninstall.
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-user_profile_data_file # Access to profile files
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-user_profile_foreign_dex_data_file # Access to profile files
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userdebug_or_eng(`
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-method_trace_data_file # only on ro.debuggable=1
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-coredump_file # userdebug/eng only
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')
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}:dir_file_class_set { create unlink };
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# Do not allow untrusted apps to directly open tun_device
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neverallow { untrusted_app_all ephemeral_app isolated_app } tun_device:chr_file open;
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# Only allow appending to /data/anr/traces.txt (b/27853304, b/18340553)
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neverallow { untrusted_app_all ephemeral_app isolated_app } anr_data_file:file ~{ open append };
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neverallow { untrusted_app_all ephemeral_app isolated_app } anr_data_file:dir ~search;
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# Avoid reads from generically labeled /proc files
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# Create a more specific label if needed
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neverallow { untrusted_app_all ephemeral_app isolated_app } proc:file { no_rw_file_perms no_x_file_perms };
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