platform_system_sepolicy/private/coredomain.te
Martijn Coenen 1bbda7e662 Initial sepolicy for app_zygote.
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
2019-01-21 08:24:41 +00:00

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get_prop(coredomain, pm_prop)
get_prop(coredomain, exported_pm_prop)
full_treble_only(`
neverallow {
coredomain
# for chowning
-init
# generic access to sysfs_type
-ueventd
-vold
} sysfs_leds:file *;
')
# On TREBLE devices, a limited set of files in /vendor are accessible to
# only a few whitelisted coredomains to keep system/vendor separation.
full_treble_only(`
# Limit access to /vendor/app
neverallow {
coredomain
-appdomain
-dex2oat
-idmap
-init
-installd
userdebug_or_eng(`-perfprofd')
userdebug_or_eng(`-heapprofd')
-postinstall_dexopt
-rs # spawned by appdomain, so carryover the exception above
-system_server
} vendor_app_file:dir { open read getattr search };
')
full_treble_only(`
neverallow {
coredomain
-appdomain
-dex2oat
-idmap
-init
-installd
userdebug_or_eng(`-perfprofd')
userdebug_or_eng(`-heapprofd')
-postinstall_dexopt
-rs # spawned by appdomain, so carryover the exception above
-system_server
-mediaserver
} vendor_app_file:file r_file_perms;
')
full_treble_only(`
# Limit access to /vendor/overlay
neverallow {
coredomain
-appdomain
-idmap
-init
-installd
-rs # spawned by appdomain, so carryover the exception above
-system_server
-app_zygote
-webview_zygote
-zygote
userdebug_or_eng(`-heapprofd')
} vendor_overlay_file:dir { getattr open read search };
')
full_treble_only(`
neverallow {
coredomain
-appdomain
-idmap
-init
-installd
-rs # spawned by appdomain, so carryover the exception above
-system_server
-app_zygote
-webview_zygote
-zygote
userdebug_or_eng(`-heapprofd')
} vendor_overlay_file:file r_file_perms;
')
# Core domains are not permitted to use kernel interfaces which are not
# explicitly labeled.
# TODO(b/65643247): Apply these neverallow rules to all coredomain.
full_treble_only(`
# /proc
neverallow {
coredomain
-vold
} proc:file no_rw_file_perms;
# /sys
neverallow {
coredomain
-init
-ueventd
-vold
} sysfs:file no_rw_file_perms;
# /dev
neverallow {
coredomain
-fsck
-init
-ueventd
} device:{ blk_file file } no_rw_file_perms;
# debugfs
neverallow {
coredomain
-dumpstate
-init
-system_server
} debugfs:file no_rw_file_perms;
# tracefs
neverallow {
coredomain
-atrace
-dumpstate
-init
userdebug_or_eng(`-perfprofd')
-traced_probes
-shell
-traceur_app
} debugfs_tracing:file no_rw_file_perms;
# inotifyfs
neverallow {
coredomain
-init
} inotify:file no_rw_file_perms;
# pstorefs
neverallow {
coredomain
-bootstat
-charger
-dumpstate
-healthd
userdebug_or_eng(`-incidentd')
-init
-logd
-logpersist
-recovery_persist
-recovery_refresh
-shell
-system_server
} pstorefs:file no_rw_file_perms;
# configfs
neverallow {
coredomain
-init
-system_server
} configfs:file no_rw_file_perms;
# functionfs
neverallow {
coredomain
-adbd
-init
-mediaprovider
-system_server
} functionfs:file no_rw_file_perms;
# usbfs and binfmt_miscfs
neverallow {
coredomain
-init
}{ usbfs binfmt_miscfs }:file no_rw_file_perms;
')
# Following /dev nodes must not be directly accessed by coredomain, but should
# instead be wrapped by HALs.
neverallow coredomain {
iio_device
radio_device
}:chr_file { open read append write ioctl };
# TODO(b/120243891): HAL permission to tee_device is included into coredomain
# on non-Treble devices.
full_treble_only(`
neverallow coredomain tee_device:chr_file { open read append write ioctl };
')