Merge "Modify sepolicy for compos key changes" am: 5273f3a486

Original change: https://android-review.googlesource.com/c/platform/system/sepolicy/+/1988307

Change-Id: I09762bb3672b50549dcd492f9d8031e552825576

apex/com.android.compos-file_contexts

@@ -1,4 +1,5 @@
 (/.*)?                   u:object_r:system_file:s0
-/bin/compsvc             u:object_r:compos_exec:s0
-/bin/compos_verify_key   u:object_r:compos_verify_key_exec:s0
+/bin/compos_key_helper   u:object_r:compos_key_helper_exec:s0
+/bin/compos_verify       u:object_r:compos_verify_exec:s0
 /bin/composd             u:object_r:composd_exec:s0
+/bin/compsvc             u:object_r:compos_exec:s0

microdroid/system/private/compos.te

@@ -30,5 +30,10 @@ dontaudit compos self:dir write;
 # See b/35323867#comment3
 dontaudit compos self:global_capability_class_set dac_override;
 
-# Allow domain transition into odrefresh.
+# Allow running odrefresh in its own domain
 domain_auto_trans(compos, odrefresh_exec, odrefresh)
+
+# Allow running compos_key_helper in its own domain
+domain_auto_trans(compos, compos_key_helper_exec, compos_key_helper)
+# And killing it on error
+allow compos compos_key_helper:process sigkill;

microdroid/system/private/compos_key_helper.te

@@ -0,0 +1,20 @@
+# Helper process for compos to perform key derivation & signing
+type compos_key_helper, domain, coredomain;
+type compos_key_helper_exec, exec_type, file_type, system_file_type;
+
+# This domain has access to DICE secrets & the private signing key.
+# Block crash dumps to ensure the secrets are not leaked.
+typeattribute compos_key_helper no_crash_dump_domain;
+
+# Allow using DICE binder service
+binder_use(compos_key_helper);
+allow compos_key_helper dice_node_service:service_manager find;
+binder_call(compos_key_helper, diced);
+allow compos_key_helper diced:diced { get_attestation_chain derive };
+
+# Communicate with compos via stdin/stdout pipes
+allow compos_key_helper compos:fd use;
+allow compos_key_helper compos:fifo_file { getattr read write };
+
+# Write to /dev/kmsg.
+allow compos_key_helper kmsg_device:chr_file rw_file_perms;

microdroid/system/private/diced.te

@@ -1,6 +1,9 @@
 type diced, domain, coredomain;
 type diced_exec, system_file_type, exec_type, file_type;
 
+# Block crash dumps to ensure the DICE secrets are not leaked.
+typeattribute diced no_crash_dump_domain;
+
 # diced can be started by init
 init_daemon_domain(diced)
 

microdroid/system/private/domain.te

@@ -263,9 +263,7 @@ allow domain kernel:key search;
 
 # Transition to crash_dump when /system/bin/crash_dump* is executed.
 # This occurs when the process crashes.
-# We do not apply this to the su domain to avoid interfering with
-# tests (b/114136122)
-domain_auto_trans(domain, crash_dump_exec, crash_dump);
+domain_auto_trans({domain -no_crash_dump_domain}, crash_dump_exec, crash_dump);
 allow domain crash_dump:process sigchld;
 
 # Properties that microdroid doesn't have but some still want to read.
@@ -605,3 +603,7 @@ neverallow { domain -init -vendor_init } debugfs_tracing_printk_formats:file *;
 
 # Linux lockdown "integrity" level is enforced for user builds.
 neverallow { domain userdebug_or_eng(`-domain') } self:lockdown integrity;
+
+# These domains must not be crash dumped
+neverallow no_crash_dump_domain crash_dump_exec:file no_x_file_perms;
+neverallow no_crash_dump_domain crash_dump:process { transition dyntransition };

microdroid/system/public/attributes

@@ -373,3 +373,6 @@ attribute fusefs_type;
 
 # All types run from microdroid_manager as a payload
 attribute microdroid_payload;
+
+# Domains that are blocked from producing a crash dump
+attribute no_crash_dump_domain;

microdroid/vendor/hal_dice_default.te

@@ -1,6 +1,9 @@
 type hal_dice_default, domain;
 hal_server_domain(hal_dice_default, hal_dice)
 
+# Block crash dumps to ensure the DICE secrets are not leaked.
+typeattribute hal_dice_default no_crash_dump_domain;
+
 type hal_dice_default_exec, exec_type, vendor_file_type, file_type;
 init_daemon_domain(hal_dice_default)
 

private/compos.te

@@ -1 +0,0 @@
-type compos_exec, exec_type, file_type, system_file_type;

private/compos_verify.te

@@ -0,0 +1,23 @@
+# 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);
+
+# Access instance image files
+allow compos_verify apex_module_data_file:dir search;
+r_dir_file(compos_verify, apex_compos_data_file)
+
+# 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;

private/compos_verify_key.te

@@ -1,20 +0,0 @@
-# Run by odsign to verify a CompOs instance's keys.
-type compos_verify_key, domain, coredomain;
-
-type compos_verify_key_exec, exec_type, file_type, system_file_type;
-
-binder_use(compos_verify_key);
-virtualizationservice_use(compos_verify_key);
-
-# Access the image & key files, delete on failure, rename pending to current
-allow compos_verify_key apex_module_data_file:dir search;
-allow compos_verify_key apex_compos_data_file:dir create_dir_perms;
-allow compos_verify_key apex_compos_data_file:file create_file_perms;
-
-# Allow odsign to redirect our stdout/stderr to log
-allow compos_verify_key odsign:fd use;
-allow compos_verify_key odsign_devpts:chr_file { read write };
-
-# Only odsign can enter the domain via exec
-neverallow { domain -odsign } compos_verify_key:process transition;
-neverallow * compos_verify_key:process dyntransition;

private/file.te

@@ -88,6 +88,11 @@ type kvm_device, dev_type;
 # /apex/com.android.virt/bin/fd_server
 type fd_server_exec, system_file_type, exec_type, file_type;
 
+# /apex/com.android.compos/bin/compsvc
+type compos_exec, exec_type, file_type, system_file_type;
+# /apex/com.android.compos/bin/compos_key_helper
+type compos_key_helper_exec, exec_type, file_type, system_file_type;
+
 # /metadata/sepolicy
 type sepolicy_metadata_file, file_type;
 

private/odsign.te

@@ -54,8 +54,8 @@ domain_auto_trans(odsign, odrefresh_exec, odrefresh)
 # Run fsverity_init to add key to fsverity keyring
 domain_auto_trans(odsign, fsverity_init_exec, fsverity_init)
 
-# Run compos_verify_key to verify CompOs instances
-domain_auto_trans(odsign, compos_verify_key_exec, compos_verify_key)
+# Run compos_verify to verify CompOs signatures
+domain_auto_trans(odsign, compos_verify_exec, compos_verify)
 
 # only odsign can set odsign sysprop
 set_prop(odsign, odsign_prop)