platform_system_sepolicy/private/compos_verify.te
Alan Stokes 1035ba1023 Allow compos_verify to write VM logs
Previously I've resisted granting write access to these files, since
it allows the instance image to be altered. But that doesn't allow an
attacker to do anything other than render it invalid, since it's
protected by the VM key.

Note that logs are only written when the VM is debuggable, which is
currently only when only non-protected VMs are available.

Bug: 235350758
Test: Force debug on, stage APEX, compile, reboot -> see vm logs
Test: Presubmit
Change-Id: I17c9a17db83d15adfab97b8cfe4ccd67393a08c1
2022-06-17 13:41:51 +01:00

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# Run by odsign to verify a CompOS signature
type compos_verify, domain, coredomain;
type compos_verify_exec, exec_type, file_type, system_file_type;
# Start a VM
binder_use(compos_verify);
virtualizationservice_use(compos_verify);
# Read instance image & write VM logs
allow compos_verify apex_module_data_file:dir search;
allow compos_verify apex_compos_data_file:dir rw_dir_perms;
allow compos_verify apex_compos_data_file:file { rw_file_perms create };
# Read CompOS info & signature files
allow compos_verify apex_art_data_file:dir search;
allow compos_verify apex_art_data_file:file r_file_perms;
# Allow odsign to redirect our stdout/stderr to log
allow compos_verify odsign:fd use;
allow compos_verify odsign_devpts:chr_file { read write };
# Only odsign can enter the domain via exec
neverallow { domain -odsign } compos_verify:process transition;
neverallow * compos_verify:process dyntransition;