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
74 lines
2.8 KiB
Text
74 lines
2.8 KiB
Text
# mediaextractor - multimedia daemon
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type mediaextractor, domain;
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type mediaextractor_exec, exec_type, file_type;
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typeattribute mediaextractor mlstrustedsubject;
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binder_use(mediaextractor)
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binder_call(mediaextractor, binderservicedomain)
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binder_call(mediaextractor, appdomain)
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binder_service(mediaextractor)
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add_service(mediaextractor, mediaextractor_service)
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allow mediaextractor mediametrics_service:service_manager find;
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allow mediaextractor hidl_token_hwservice:hwservice_manager find;
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allow mediaextractor system_server:fd use;
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hal_client_domain(mediaextractor, hal_cas)
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r_dir_file(mediaextractor, cgroup)
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allow mediaextractor proc_meminfo:file r_file_perms;
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crash_dump_fallback(mediaextractor)
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# allow mediaextractor read permissions for file sources
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allow mediaextractor sdcardfs:file { getattr read };
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allow mediaextractor media_rw_data_file:file { getattr read };
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allow mediaextractor { app_data_file privapp_data_file }:file { getattr read };
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# Read resources from open apk files passed over Binder
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allow mediaextractor apk_data_file:file { read getattr };
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allow mediaextractor asec_apk_file:file { read getattr };
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allow mediaextractor ringtone_file:file { read getattr };
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# scan extractor library directory to dynamically load extractors
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allow mediaextractor system_file:dir { read open };
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userdebug_or_eng(`
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# Allow extractor to add update service.
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add_service(mediaextractor, mediaextractor_update_service)
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# Allow extractor to load media extractor plugins from update apk.
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allow mediaextractor apk_data_file:dir search;
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allow mediaextractor apk_data_file:file { execute open };
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')
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###
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### neverallow rules
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###
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# mediaextractor should never execute any executable without a
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# domain transition
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neverallow mediaextractor { file_type fs_type }:file execute_no_trans;
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# The goal of the mediaserver split is to place media processing code into
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# restrictive sandboxes with limited responsibilities and thus limited
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# permissions. Example: Audioserver is only responsible for controlling audio
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# hardware and processing audio content. Cameraserver does the same for camera
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# hardware/content. Etc.
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#
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# Media processing code is inherently risky and thus should have limited
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# permissions and be isolated from the rest of the system and network.
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# Lengthier explanation here:
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# https://android-developers.googleblog.com/2016/05/hardening-media-stack.html
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neverallow mediaextractor domain:{ tcp_socket udp_socket rawip_socket } *;
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# mediaextractor should not be opening /data files directly. Any files
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# it touches (with a few exceptions) need to be passed to it via a file
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# descriptor opened outside the process.
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neverallow mediaextractor {
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data_file_type
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-zoneinfo_data_file # time zone data from /data/misc/zoneinfo
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userdebug_or_eng(`-apk_data_file') # for loading media extractor plugins
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}:file open;
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