platform_system_sepolicy/private/crosvm.te
Alan Stokes 39f497013c SEPolicy for compos_verify_key.
Remove some allow rules for odsign, since it no longer directly
modifies CompOs files. Instead allow it to run compos_verify_key in
its own domain.

Grant compos_verify_key what it needs to access the CompOs files and
start up the VM.

Currently we directly connect to the CompOs VM; that will change once
some in-flight CLs have landed.

As part of this I moved the virtualizationservice_use macro to
te_macros so I can use it here. I also expanded it to include
additional grants needed by any VM client that were previously done
for individual domains (and then deleted those rules as now
redundant).

I also removed the grant of VM access to all apps; instead we allow it
for untrusted apps, on userdebug or eng builds only. (Temporarily at
least.)

Bug: 193603140
Test: Manual - odsign successfully runs the VM at boot when needed.
Change-Id: I62f9ad8c7ea2fb9ef2d468331e26822d08e3c828
2021-09-03 16:31:02 +01:00

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type crosvm, domain, coredomain;
type crosvm_exec, system_file_type, exec_type, file_type;
type crosvm_tmpfs, file_type;
# Let crosvm open /dev/kvm.
allow crosvm kvm_device:chr_file rw_file_perms;
# Most other domains shouldn't access /dev/kvm.
neverallow { domain -crosvm -ueventd -shell } kvm_device:chr_file getattr;
neverallow { domain -crosvm -ueventd } kvm_device:chr_file ~getattr;
# Let crosvm create temporary files.
tmpfs_domain(crosvm)
# Let crosvm receive file descriptors from VirtualizationService.
allow crosvm virtualizationservice:fd use;
# Let crosvm read the composite disk images (virtualizationservice_data_file), APEXes
# (staging_data_file), APKs (apk_data_file and shell_data_file where the latter is for test apks in
# /data/local/tmp), and instance.img (app_data_file). Note that the open permission is not given as
# the files are passed as file descriptors.
allow crosvm {
virtualizationservice_data_file
staging_data_file
apk_data_file
app_data_file
apex_compos_data_file
userdebug_or_eng(`shell_data_file')
}:file { getattr read ioctl lock };
# Allow searching the directory where the composite disk images are.
allow crosvm virtualizationservice_data_file:dir search;
# Don't allow crosvm to open files that it doesn't own.
neverallow crosvm {
virtualizationservice_data_file
staging_data_file
apk_data_file
app_data_file
userdebug_or_eng(`-shell_data_file')
}:file open;
# The instance image and the composite image should be writable as well because they could represent
# mutable disks.
allow crosvm {
virtualizationservice_data_file
app_data_file
apex_compos_data_file
}:file write;
# Allow crosvm to pipe console log to shell or app which could be the owner of a VM.
allow crosvm adbd:fd use;
allow crosvm adbd:unix_stream_socket { read write };
allow crosvm appdomain:fifo_file { read write };
# The console log can also be written to /data/local/tmp. This is not safe as the log then can be
# visible to the processes which don't own the VM. Therefore, this is a debugging only feature.
userdebug_or_eng(`allow crosvm shell_data_file:file w_file_perms;')
# Don't allow crosvm to have access to ordinary vendor files that are not for VMs.
full_treble_only(`
neverallow crosvm {
vendor_file_type
-vendor_vm_file
-vendor_vm_data_file
# These types are not required for crosvm, but the access is granted to globally in domain.te
# thus should be exempted here.
-vendor_configs_file
-vndk_sp_file
-vendor_task_profiles_file
}:file *;
')