illumos gate

If you attempt to run a ZFS channel program which is given hidden_args in the argument nvlist for the Lua program, the code in lzc_channel_program_impl pulls the hidden_args out into a top-level key of the ioctl nvlist. This is meant to keep the values out of the SPA history log (e.g. for secret key data when manipulating encrypted datasets).

The code in zfs_ioc_channel_program understands how to look for this extra key and use it, but it was never added to the zfs_ioc_key_t for the ioctl (zfs_keys_channel_program). This means that when zfs_check_input_nvpairs processes an ioctl with this key actually set in the top-level nvlist, it rejects it, returning errno 1034 (ZFS_ERR_IOC_ARG_UNAVAIL).

This makes the hidden_args feature rather challenging to use.