On Wed, 2020-07-29 at 10:58 -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>
Other than one change and one question below, it looks good.
Reviewed-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
<snip>
> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> index 85000dc8595c..1a7bc4c7437d 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -706,7 +697,7 @@ int ima_load_data(enum kernel_load_data_id id, bool contents)
> }
> break;
> case LOADING_FIRMWARE:
> - if (ima_enforce && (ima_appraise & IMA_APPRAISE_FIRMWARE)) {
> + if (ima_enforce && (ima_appraise & IMA_APPRAISE_FIRMWARE) && !contents) {
> pr_err("Prevent firmware sysfs fallback loading.\n");
Appended signatures are limited to kernel modules and, more recently,
to the kexec kernel image, not firmware. Without a file descriptor,
file signatures stored as an xattrs are not applicable either. We
might as well fail earlier, rather than later. Adding "!contents" is
unnecessary.
> return -EACCES; /* INTEGRITY_UNKNOWN */
> }
> @@ -739,6 +730,15 @@ int ima_load_data(enum kernel_load_data_id id, bool contents)
> */
> int ima_post_load_data(char *buf, loff_t size, enum kernel_load_data_id load_id)
> {
> + if (load_id == LOADING_FIRMWARE) {
> + if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
> + (ima_appraise & IMA_APPRAISE_ENFORCE)) {
> + pr_err("Prevent firmware loading_store.\n");
> + return -EACCES; /* INTEGRITY_UNKNOWN */
> + }
> + return 0;
> + }
Even with failing LOADING_FIRMWARE early in ima_load_data(), is this
still needed for fw_sysfs_loading()?
thanks,
Mimi
> +
> return 0;
> }
>
