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@chromium.org
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?