On Mon, Jul 27, 2020 at 06:57:45AM -0400, Mimi Zohar wrote: > On Fri, 2020-07-24 at 14:36 -0700, Kees Cook wrote: > > Now that security_post_load_data() is wired up, use it instead > > of the NULL file argument style of security_post_read_file(), > > and update the security_kernel_load_data() call to indicate that a > > security_kernel_post_load_data() call is expected. > > > > Wire up the IMA check to match earlier logic. Perhaps a generalized > > change to ima_post_load_data() might look something like this: > > > > return process_buffer_measurement(buf, size, > > kernel_load_data_id_str(load_id), > > read_idmap[load_id] ?: FILE_CHECK, > > 0, NULL); > > > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > > process_measurement() measures, verifies a file signature - both > signatures stored as an xattr and as an appended buffer signature - > and augments audit records with the file hash. (Support for measuring, > augmenting audit records, and/or verifying fs-verity signatures has > yet to be added.) > > As explained in my response to 11/19, the file descriptor provides the > file pathname associated with the buffer data. In addition, IMA > policy rules may be defined in terms of other file descriptor info - > uid, euid, uuid, etc. > > Recently support was added for measuring the kexec boot command line, > certificates being loaded onto a keyring, and blacklisted file hashes > (limited to appended signatures). None of these buffers are signed. > process_buffer_measurement() was added for this reason and as a > result is limited to just measuring the buffer data. > > Whether process_measurement() or process_buffer_measurement() should > be modified, needs to be determined. In either case to support the > init_module syscall, would at minimum require the associated file > pathname. Right -- I don't intend to make changes to the init_module() syscall since it's deprecated, so this hook is more of a "fuller LSM coverage for old syscalls" addition. IMA can happily continue to ignore it, which is what I have here, but I thought I'd at least show what it *might* look like. Perhaps BPF LSM is a better example. Does anything need to change for this patch? -- Kees Cook
