Add rules for snapshotctl
snapshotctl is a shell interface for libsnapshot. After rebooting
into an updated build, on sys.boot_completed, init calls
snapshotctl to merge snapshots. In order to do that, it needs to:
- Talk to gsid to mount and unmount COW images
- read the current slot suffix to do checks (and avoid merging
snapshots when it shouldn't).
- read / write OTA metadata files to understand states of
the snapshot
- delete OTA metadata files once a snapshot is merged
- collapse the snapshot device-mapper targets into a plain
dm-linear target by re-mapping devices on device-mapper
Test: reboot after OTA, see merge completed without denials
Bug: 135752105
Change-Id: Idfe99d4004e24805d56cd0ab2479557f237c2448
diff --git a/private/snapshotctl.te b/private/snapshotctl.te
new file mode 100644
index 0000000..78bf6fd
--- /dev/null
+++ b/private/snapshotctl.te
@@ -0,0 +1,32 @@
+type snapshotctl, domain, coredomain;
+type snapshotctl_exec, system_file_type, exec_type, file_type;
+
+# Allow init to run snapshotctl and do auto domain transfer.
+init_daemon_domain(snapshotctl);
+
+# Allow to start gsid service.
+set_prop(snapshotctl, ctl_gsid_prop)
+
+# Allow to talk to gsid.
+binder_use(snapshotctl)
+allow snapshotctl gsi_service:service_manager find;
+binder_call(snapshotctl, gsid)
+
+# Allow to read/write/delete OTA metadata files for snapshot status and COW file status.
+allow snapshotctl metadata_file:dir search;
+allow snapshotctl ota_metadata_file:dir rw_dir_perms;
+allow snapshotctl ota_metadata_file:file { rw_file_perms unlink };
+
+# Allow to get A/B slot suffix from device tree or kernel cmdline.
+r_dir_file(snapshotctl, sysfs_dt_firmware_android);
+allow snapshotctl proc_cmdline:file r_file_perms;
+
+# Needed to (re-)map logical partitions.
+allow snapshotctl block_device:dir r_dir_perms;
+allow snapshotctl super_block_device:blk_file r_file_perms;
+
+# Interact with device-mapper to collapse snapshots.
+allow snapshotctl dm_device:chr_file rw_file_perms;
+
+# Needed to mutate device-mapper nodes.
+allow snapshotctl self:global_capability_class_set sys_admin;