23c9d91b46
Currently, both untrusted apps and priv-apps use the SELinux file label
"app_data_file" for files in their /data/data directory. This is
problematic, as we really want different rules for such files. For
example, we may want to allow untrusted apps to load executable code
from priv-app directories, but disallow untrusted apps from loading
executable code from their own home directories.
This change adds a new file type "privapp_data_file". For compatibility,
we adjust the policy to support access privapp_data_files almost
everywhere we were previously granting access to app_data_files
(adbd and run-as being exceptions). Additional future tightening is
possible here by removing some of these newly added rules.
This label will start getting used in a followup change to
system/sepolicy/private/seapp_contexts, similar to:
-user=_app isPrivApp=true domain=priv_app type=app_data_file levelFrom=user
+user=_app isPrivApp=true domain=priv_app type=privapp_data_file levelFrom=user
For now, this newly introduced label has no usage, so this change
is essentially a no-op.
Test: Factory reset and boot - no problems on fresh install.
Test: Upgrade to new version and test. No compatibility problems on
filesystem upgrade.
Change-Id: I9618b7d91d1c2bcb5837cdabc949f0cf741a2837
119 lines
4.8 KiB
Text
119 lines
4.8 KiB
Text
###
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### Services with isolatedProcess=true in their manifest.
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###
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### This file defines the rules for isolated apps. An "isolated
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### app" is an APP with UID between AID_ISOLATED_START (99000)
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### and AID_ISOLATED_END (99999).
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###
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typeattribute isolated_app coredomain;
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app_domain(isolated_app)
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# Access already open app data files received over Binder or local socket IPC.
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allow isolated_app { app_data_file privapp_data_file }:file { append read write getattr lock };
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allow isolated_app activity_service:service_manager find;
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allow isolated_app display_service:service_manager find;
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allow isolated_app webviewupdate_service:service_manager find;
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# Google Breakpad (crash reporter for Chrome) relies on ptrace
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# functionality. Without the ability to ptrace, the crash reporter
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# tool is broken.
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# b/20150694
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# https://code.google.com/p/chromium/issues/detail?id=475270
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allow isolated_app self:process ptrace;
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# b/32896414: Allow accessing sdcard file descriptors passed to isolated_apps
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# by other processes. Open should never be allowed, and is blocked by
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# neverallow rules below.
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# media_rw_data_file is included for sdcardfs, and can be removed if sdcardfs
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# is modified to change the secontext when accessing the lower filesystem.
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allow isolated_app { sdcard_type media_rw_data_file }:file { read write append getattr lock };
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# For webviews, isolated_app processes can be forked from the webview_zygote
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# in addition to the zygote. Allow access to resources inherited from the
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# webview_zygote process. These rules are specialized copies of the ones in app.te.
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# Inherit FDs from the webview_zygote.
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allow isolated_app webview_zygote:fd use;
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# Notify webview_zygote of child death.
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allow isolated_app webview_zygote:process sigchld;
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# Inherit logd write socket.
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allow isolated_app webview_zygote:unix_dgram_socket write;
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# Read system properties managed by webview_zygote.
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allow isolated_app webview_zygote_tmpfs:file read;
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# TODO (b/63631799) fix this access
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# suppress denials to /data/local/tmp
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dontaudit isolated_app shell_data_file:dir search;
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# Write app-specific trace data to the Perfetto traced damon. This requires
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# connecting to its producer socket and obtaining a (per-process) tmpfs fd.
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allow isolated_app traced:fd use;
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allow isolated_app traced_tmpfs:file { read write getattr map };
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unix_socket_connect(isolated_app, traced_producer, traced)
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#####
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##### Neverallow
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#####
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# Do not allow isolated_app to directly open tun_device
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neverallow isolated_app tun_device:chr_file open;
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# Isolated apps should not directly open app data files themselves.
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neverallow isolated_app { app_data_file privapp_data_file }:file open;
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# Only allow appending to /data/anr/traces.txt (b/27853304, b/18340553)
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# TODO: are there situations where isolated_apps write to this file?
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# TODO: should we tighten these restrictions further?
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neverallow isolated_app anr_data_file:file ~{ open append };
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neverallow isolated_app anr_data_file:dir ~search;
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# Isolated apps must not be permitted to use HwBinder
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neverallow isolated_app hwbinder_device:chr_file *;
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neverallow isolated_app *:hwservice_manager *;
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# Isolated apps must not be permitted to use VndBinder
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neverallow isolated_app vndbinder_device:chr_file *;
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# Isolated apps must not be permitted to perform actions on Binder and VndBinder service_manager
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# except the find actions for services whitelisted below.
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neverallow isolated_app *:service_manager ~find;
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# b/17487348
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# Isolated apps can only access three services,
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# activity_service, display_service and webviewupdate_service.
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neverallow isolated_app {
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service_manager_type
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-activity_service
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-display_service
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-webviewupdate_service
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}:service_manager find;
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# Isolated apps shouldn't be able to access the driver directly.
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neverallow isolated_app gpu_device:chr_file { rw_file_perms execute };
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# Do not allow isolated_app access to /cache
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neverallow isolated_app cache_file:dir ~{ r_dir_perms };
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neverallow isolated_app cache_file:file ~{ read getattr };
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# Do not allow isolated_app to access external storage, except for files passed
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# via file descriptors (b/32896414).
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neverallow isolated_app { storage_file mnt_user_file sdcard_type }:dir ~getattr;
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neverallow isolated_app { storage_file mnt_user_file }:file_class_set *;
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neverallow isolated_app sdcard_type:{ devfile_class_set lnk_file sock_file fifo_file } *;
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neverallow isolated_app sdcard_type:file ~{ read write append getattr lock };
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# Do not allow USB access
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neverallow isolated_app { usb_device usbaccessory_device }:chr_file *;
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# Restrict the webview_zygote control socket.
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neverallow isolated_app webview_zygote:sock_file write;
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# Limit the /sys files which isolated_app can access. This is important
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# for controlling isolated_app attack surface.
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neverallow isolated_app {
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sysfs_type
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-sysfs_devices_system_cpu
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-sysfs_usb # TODO: check with audio team if needed for isolated_app (b/28417852)
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}:file no_rw_file_perms;
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