5a0d5ccdf7
When a bug causes us to leak a file descriptor or resource in the OTA path, it can cause unremovable device-mapper devices. The companion CL in this topic attempts to diagnose such problems by performing a quick scan for things depending on an unremovable block device: mounts, loop devices, and other device-mapper nodes. To detect mounts it would normally be enough to scan /proc/mounts, but with MNT_DETACH the filesystem may still be mounted but not visible to update_engine. This is exactly what happened in b/184715543. To scan for such cases, we look for /sys/fs/ext4/<name> or /sys/fs/f2fs/<name> where <name> is the block device. To make this work, we grant update_engine r_dir_perms to sysfs and sysfs_f2fs_dir. It doesn't actually need to read the contents of any files, the presence of the inode is good enough. Bug: N/A Test: manual test Change-Id: Ib085c9c814180b360e2170135011261bbb7e35b6
98 lines
4 KiB
Text
98 lines
4 KiB
Text
# update_engine payload application permissions. These are shared between the
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# background daemon and the recovery tool to sideload an update.
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# Allow update_engine to reach block devices in /dev/block.
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allow update_engine_common block_device:dir search;
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# Allow read/write on system and boot partitions.
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allow update_engine_common boot_block_device:blk_file rw_file_perms;
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allow update_engine_common system_block_device:blk_file rw_file_perms;
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# Where ioctls are granted via standard allow rules to block devices,
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# automatically allow common ioctls that are generally needed by
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# update_engine.
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allowxperm update_engine_common dev_type:blk_file ioctl {
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BLKDISCARD
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BLKDISCARDZEROES
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BLKROGET
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BLKROSET
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BLKSECDISCARD
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BLKZEROOUT
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};
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# Allow to set recovery options in the BCB. Used to trigger factory reset when
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# the update to an older version (channel change) or incompatible version
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# requires it.
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allow update_engine_common misc_block_device:blk_file rw_file_perms;
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# read fstab
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allow update_engine_common rootfs:dir getattr;
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allow update_engine_common rootfs:file r_file_perms;
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# Allow update_engine_common to mount on the /postinstall directory and reset the
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# labels on the mounted filesystem to postinstall_file.
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allow update_engine_common postinstall_mnt_dir:dir { mounton getattr search };
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allow update_engine_common postinstall_file:filesystem { mount unmount relabelfrom relabelto };
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allow update_engine_common labeledfs:filesystem { mount unmount relabelfrom };
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# Allow update_engine_common to read and execute postinstall_file.
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allow update_engine_common postinstall_file:file rx_file_perms;
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allow update_engine_common postinstall_file:lnk_file r_file_perms;
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allow update_engine_common postinstall_file:dir r_dir_perms;
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# install update.zip from cache
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r_dir_file(update_engine_common, cache_file)
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# A postinstall program is typically a shell script (with a #!), so we allow
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# to execute those.
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allow update_engine_common shell_exec:file rx_file_perms;
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# Allow update_engine_common to suspend, resume and kill the postinstall program.
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allow update_engine_common postinstall:process { signal sigstop sigkill };
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# access /proc/cmdline
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allow update_engine_common proc_cmdline:file r_file_perms;
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# Read files in /sys/firmware/devicetree/base/firmware/android/
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r_dir_file(update_engine_common, sysfs_dt_firmware_android)
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# Needed because libdm reads sysfs to validate when a dm path is ready.
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r_dir_file(update_engine_common, sysfs_dm)
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# Scan files in /sys/fs/ext4 and /sys/fs/f2fs for device-mapper diagnostics.
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allow update_engine_common sysfs:dir r_dir_perms;
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allow update_engine_common sysfs_fs_f2fs:dir r_dir_perms;
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# read / write on /dev/device-mapper to map / unmap devices
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allow update_engine_common dm_device:chr_file rw_file_perms;
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# apply / verify updates on devices mapped via device mapper
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allow update_engine_common dm_device:blk_file rw_file_perms;
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# read /dev/dm-user, so that we can inotify wait for control devices to be
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# asynchronously created by ueventd.
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allow update_engine dm_user_device:dir r_dir_perms;
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# read / write metadata on super device to resize partitions
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allow update_engine_common super_block_device_type:blk_file rw_file_perms;
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# ioctl on super device to get block device alignment and alignment offset
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allowxperm update_engine_common super_block_device_type:blk_file ioctl { BLKIOMIN BLKALIGNOFF };
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# get physical block device to map logical partitions on device mapper
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allow update_engine_common block_device:dir r_dir_perms;
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# Allow update_engine_common to write to statsd socket.
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unix_socket_send(update_engine_common, statsdw, statsd)
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# Allow to read Virtual A/B feature flags.
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get_prop(update_engine_common, virtual_ab_prop)
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# Allow to read GKI related flags.
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get_prop(update_engine_common, ab_update_gki_prop)
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get_prop(update_engine_common, build_bootimage_prop)
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# Allow to read/write/create OTA metadata files for snapshot status and COW file status.
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allow update_engine_common metadata_file:dir search;
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allow update_engine_common ota_metadata_file:dir rw_dir_perms;
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allow update_engine_common ota_metadata_file:file create_file_perms;
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