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    SubjectRe: [PATCH v3 12/19] firmware_loader: Use security_post_load_data()
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    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.

    Mimi

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