1bbda7e662
The application zygote is a new sort of zygote process that is a child of the regular zygote. Each application zygote is tied to the application for which it's launched. Once it's started, it will pre-load some of the code for that specific application, much like the regular zygote does for framework code. Once the application zygote is up and running, it can spawn isolated service processes that run in the isolated_app domain. These services can then benefit from already having the relevant application code and data pre-loaded. The policy is largely the same as the webview_zygote domain, however there are a few crucial points where the policy is different. 1) The app_zygote runs under the UID of the application that spawned it. 2) During app_zygote launch, it will call a callback that is controlled by the application, that allows the application to pre-load code and data that it thinks is relevant. Especially point 2 is imporant: it means that untrusted code can run in the app_zygote context. This context is severely limited, and the main concern is around the setgid/setuid capabilities. Those conerns are mitigated by installing a seccomp filter that only allows setgid/setuid to be called in a safe range. Bug: 111434506 Test: app_zygote can start and fork children without denials. Change-Id: I1cc49ee0042d41e5ac6eb81d8f8a10ba448d4832
161 lines
5.5 KiB
Text
161 lines
5.5 KiB
Text
# zygote
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typeattribute zygote coredomain;
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typeattribute zygote mlstrustedsubject;
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init_daemon_domain(zygote)
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read_runtime_log_tags(zygote)
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# Override DAC on files and switch uid/gid.
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allow zygote self:global_capability_class_set { dac_override dac_read_search setgid setuid fowner chown };
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# Drop capabilities from bounding set.
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allow zygote self:global_capability_class_set setpcap;
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# Switch SELinux context to app domains.
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allow zygote self:process setcurrent;
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allow zygote system_server_startup:process dyntransition;
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allow zygote appdomain:process dyntransition;
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allow zygote webview_zygote:process dyntransition;
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allow zygote app_zygote:process dyntransition;
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# Allow zygote to read app /proc/pid dirs (b/10455872).
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allow zygote appdomain:dir { getattr search };
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allow zygote appdomain:file { r_file_perms };
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# Move children into the peer process group.
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allow zygote system_server:process { getpgid setpgid };
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allow zygote appdomain:process { getpgid setpgid };
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allow zygote webview_zygote:process { getpgid setpgid };
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allow zygote app_zygote:process { getpgid setpgid };
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# Read system data.
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allow zygote system_data_file:dir r_dir_perms;
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allow zygote system_data_file:file r_file_perms;
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# Write to /data/dalvik-cache.
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allow zygote dalvikcache_data_file:dir create_dir_perms;
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allow zygote dalvikcache_data_file:file create_file_perms;
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# Create symlinks in /data/dalvik-cache.
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allow zygote dalvikcache_data_file:lnk_file create_file_perms;
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# Write to /data/resource-cache.
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allow zygote resourcecache_data_file:dir rw_dir_perms;
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allow zygote resourcecache_data_file:file create_file_perms;
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# When WITH_DEXPREOPT is true, the zygote does not load executable content from
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# /data/dalvik-cache. Executable files loaded from /data is a persistence vector
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# we want to avoid. See
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# https://bugs.chromium.org/p/project-zero/issues/detail?id=955 for example.
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allow { zygote with_dexpreopt(`-zygote') } dalvikcache_data_file:file execute;
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# Allow zygote to create JIT memory.
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allow zygote self:process execmem;
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# Execute idmap and dex2oat within zygote's own domain.
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# TODO: Should either of these be transitioned to the same domain
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# used by installd or stay in-domain for zygote?
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allow zygote idmap_exec:file rx_file_perms;
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allow zygote dex2oat_exec:file rx_file_perms;
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# Allow apps access to /vendor/overlay
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r_dir_file(zygote, vendor_overlay_file)
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# Control cgroups.
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allow zygote cgroup:dir create_dir_perms;
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allow zygote cgroup:{ file lnk_file } r_file_perms;
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allow zygote self:global_capability_class_set sys_admin;
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# Allow zygote to stat the files that it opens. The zygote must
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# be able to inspect them so that it can reopen them on fork
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# if necessary: b/30963384.
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allow zygote pmsg_device:chr_file getattr;
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allow zygote debugfs_trace_marker:file getattr;
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# Get seapp_contexts
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allow zygote seapp_contexts_file:file r_file_perms;
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# Check validity of SELinux context before use.
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selinux_check_context(zygote)
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# Check SELinux permissions.
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selinux_check_access(zygote)
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# Native bridge functionality requires that zygote replaces
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# /proc/cpuinfo with /system/lib/<ISA>/cpuinfo using a bind mount
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allow zygote proc_cpuinfo:file mounton;
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# Allow remounting rootfs as MS_SLAVE.
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allow zygote rootfs:dir mounton;
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allow zygote tmpfs:filesystem { mount unmount };
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allow zygote fuse:filesystem { unmount };
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allow zygote sdcardfs:filesystem { unmount };
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# Allow creating user-specific storage source if started before vold.
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allow zygote mnt_user_file:dir create_dir_perms;
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allow zygote mnt_user_file:lnk_file create_file_perms;
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allow zygote mnt_user_file:file create_file_perms;
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# Allowed to mount user-specific storage into place
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allow zygote storage_file:dir { search mounton };
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# Allow mounting on sdcardfs dirs
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allow zygote sdcardfs:dir { search mounton };
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# Handle --invoke-with command when launching Zygote with a wrapper command.
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allow zygote zygote_exec:file rx_file_perms;
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# Allow zygote to write to statsd.
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unix_socket_send(zygote, statsdw, statsd)
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# Root fs.
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r_dir_file(zygote, rootfs)
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# System file accesses.
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r_dir_file(zygote, system_file)
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userdebug_or_eng(`
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# Allow zygote to create and write method traces in /data/misc/trace.
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allow zygote method_trace_data_file:dir w_dir_perms;
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allow zygote method_trace_data_file:file { create w_file_perms };
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')
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allow zygote ion_device:chr_file r_file_perms;
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allow zygote tmpfs:dir r_dir_perms;
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allow zygote same_process_hal_file:file { execute read open getattr map };
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# Let the zygote access overlays so it can initialize the AssetManager.
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get_prop(zygote, overlay_prop)
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get_prop(zygote, exported_overlay_prop)
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# ingore spurious denials
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dontaudit zygote self:global_capability_class_set sys_resource;
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###
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### neverallow rules
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###
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# Ensure that all types assigned to app processes are included
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# in the appdomain attribute, so that all allow and neverallow rules
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# written on appdomain are applied to all app processes.
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# This is achieved by ensuring that it is impossible for zygote to
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# setcon (dyntransition) to any types other than those associated
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# with appdomain plus system_server_startup, webview_zygote and
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# app_zygote.
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neverallow zygote ~{
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appdomain
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system_server_startup
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webview_zygote
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app_zygote
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}:process dyntransition;
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# Zygote should never execute anything from /data except for /data/dalvik-cache files.
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neverallow zygote {
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data_file_type
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-dalvikcache_data_file # map PROT_EXEC
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}:file no_x_file_perms;
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# Do not allow access to Bluetooth-related system properties and files
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neverallow zygote {
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bluetooth_a2dp_offload_prop
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bluetooth_prop
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exported_bluetooth_prop
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}:file create_file_perms;
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