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201 lines
6.1 KiB
201 lines
6.1 KiB
# gsid - Manager for GSI Installation
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type gsid, domain;
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type gsid_exec, exec_type, file_type, system_file_type;
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typeattribute gsid coredomain;
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init_daemon_domain(gsid)
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binder_use(gsid)
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binder_service(gsid)
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add_service(gsid, gsi_service)
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# Manage DSU metadata encryption key through vold.
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allow gsid vold_service:service_manager find;
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binder_call(gsid, vold)
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set_prop(gsid, gsid_prop)
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# Needed to create/delete device-mapper nodes, and read/write to them.
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allow gsid dm_device:chr_file rw_file_perms;
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allow gsid dm_device:blk_file rw_file_perms;
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allow gsid self:global_capability_class_set sys_admin;
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dontaudit gsid self:global_capability_class_set dac_override;
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# On FBE devices (not using dm-default-key), gsid will use loop devices to map
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# images rather than device-mapper.
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allow gsid loop_control_device:chr_file rw_file_perms;
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allow gsid loop_device:blk_file rw_file_perms;
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allowxperm gsid loop_device:blk_file ioctl {
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LOOP_GET_STATUS64
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LOOP_SET_STATUS64
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LOOP_SET_FD
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LOOP_SET_BLOCK_SIZE
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LOOP_SET_DIRECT_IO
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LOOP_CLR_FD
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BLKFLSBUF
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};
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# libfiemap_writer uses sysfs to derive the bottom of a device-mapper stacking.
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# This requires traversing /sys/block/dm-N/slaves/* and reading the list of
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# file names.
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r_dir_file(gsid, sysfs_dm)
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# libfiemap_writer needs to read /sys/fs/f2fs/<dev>/features to determine
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# whether pin_file support is enabled.
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r_dir_file(gsid, sysfs_fs_f2fs)
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# Needed to read fstab, which is used to validate that system verity does not
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# use check_once_at_most for sdcard installs. (Note: proc_cmdline is needed
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# to get the A/B slot suffix).
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allow gsid proc_cmdline:file r_file_perms;
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allow gsid sysfs_dt_firmware_android:dir r_dir_perms;
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allow gsid sysfs_dt_firmware_android:file r_file_perms;
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# Needed to stat /data/gsi/* and realpath on /dev/block/by-name/*
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allow gsid block_device:dir r_dir_perms;
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# liblp queries these block alignment properties.
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allowxperm gsid { userdata_block_device sdcard_block_device }:blk_file ioctl {
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BLKIOMIN
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BLKALIGNOFF
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};
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# When installing images to an sdcard, gsid needs to be able to stat() the
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# block device. gsid also calls realpath() to remove symlinks.
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allow gsid mnt_media_rw_file:dir r_dir_perms;
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allow gsid mnt_media_rw_stub_file:dir r_dir_perms;
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# When installing images to an sdcard, gsid must bypass sdcardfs and install
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# directly to vfat, which supports the FIBMAP ioctl.
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allow gsid vfat:dir create_dir_perms;
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allow gsid vfat:file create_file_perms;
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allow gsid sdcard_block_device:blk_file r_file_perms;
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# This is needed for FIBMAP unfortunately. Oddly FIEMAP does not carry this
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# requirement, but the kernel does not implement FIEMAP support for VFAT.
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allow gsid self:global_capability_class_set sys_rawio;
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# Allow rules for gsi_tool.
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userdebug_or_eng(`
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# gsi_tool passes the system image over the adb connection, via stdin.
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allow gsid adbd:fd use;
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# Needed when running gsi_tool through "su root" rather than adb root.
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allow gsid adbd:unix_stream_socket rw_socket_perms;
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# gsi_tool passes a FIFO to gsid if invoked with pipe redirection.
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allow gsid { shell su }:fifo_file r_file_perms;
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# Allow installing images from /storage/emulated/...
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allow gsid sdcard_type:file r_file_perms;
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')
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neverallow {
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domain
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-gsid
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-init
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-update_engine_common
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-recovery
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-fastbootd
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} gsid_prop:property_service set;
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# gsid needs to store images on /data, but cannot use file I/O. If it did, the
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# underlying blocks would be encrypted, and we couldn't mount the GSI image in
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# first-stage init. So instead of directly writing to /data, we:
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#
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# 1. fallocate a file large enough to hold the signed GSI
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# 2. extract its block layout with FIEMAP
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# 3. create a dm-linear device using the FIEMAP, targeting /dev/block/by-name/userdata
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# 4. write system_gsi into that dm device
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#
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# To make this process work, we need to unwrap the device-mapper stacking for
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# userdata to reach the underlying block device. To verify the result we use
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# stat(), which requires read access.
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allow gsid userdata_block_device:blk_file r_file_perms;
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# gsid uses /metadata/gsi to communicate GSI boot information to first-stage
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# init. It cannot use userdata since data cannot be decrypted during this
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# stage.
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#
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# gsid uses /metadata/gsi to store three files:
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# install_status - A short string indicating whether a GSI image is bootable.
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# lp_metadata - LpMetadata blob describing the block ranges on userdata
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# where system_gsi resides.
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# booted - An empty file that, if exists, indicates that a GSI is
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# currently running.
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#
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allow gsid metadata_file:dir { search getattr };
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allow gsid {
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gsi_metadata_file_type
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}:dir create_dir_perms;
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allow gsid {
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ota_metadata_file
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}:dir rw_dir_perms;
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allow gsid {
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gsi_metadata_file_type
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ota_metadata_file
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}:file create_file_perms;
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# Allow restorecon to fix context of gsi_public_metadata_file.
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allow gsid file_contexts_file:file r_file_perms;
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allow gsid gsi_metadata_file:file relabelfrom;
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allow gsid gsi_public_metadata_file:file relabelto;
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allow gsid {
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gsi_data_file
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ota_image_data_file
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}:dir rw_dir_perms;
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allow gsid {
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gsi_data_file
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ota_image_data_file
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}:file create_file_perms;
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allowxperm gsid {
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gsi_data_file
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ota_image_data_file
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}:file ioctl {
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FS_IOC_FIEMAP
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FS_IOC_GETFLAGS
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};
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allow gsid system_server:binder call;
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# Prevent most processes from writing to gsi_metadata_file_type, but allow
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# adding rules for path resolution of gsi_public_metadata_file and reading
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# gsi_public_metadata_file.
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neverallow {
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domain
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-init
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-gsid
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-fastbootd
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} gsi_metadata_file_type:dir no_w_dir_perms;
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neverallow {
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domain
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-init
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-gsid
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-fastbootd
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} { gsi_metadata_file_type -gsi_public_metadata_file }:file_class_set *;
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neverallow {
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domain
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-init
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-gsid
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-fastbootd
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} gsi_public_metadata_file:file_class_set ~{ r_file_perms };
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# Prevent apps from accessing gsi_metadata_file_type.
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neverallow {
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appdomain
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-shell
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} gsi_metadata_file_type:dir_file_class_set *;
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neverallow {
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domain
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-init
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-gsid
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} gsi_data_file:dir_file_class_set *;
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neverallow {
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domain
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-gsid
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} gsi_data_file:file_class_set ~{ relabelto getattr };
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