@@ -452,6 +452,15 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
return 0;
}
+ if (read_id == READING_FIRMWARE_PREALLOC_BUFFER) {
+ if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
+ (ima_appraise & IMA_APPRAISE_ENFORCE)) {
+ pr_err("Prevent device from accessing firmware prior to verifying the firmware signature.\n");
+ return -EACCES;
+ }
+ return 0;
+ }
+
if (read_id == READING_FIRMWARE_FALLBACK_SYSFS) {
if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
(ima_appraise & IMA_APPRAISE_ENFORCE)) {
Question: can the device access the pre-allocated buffer at any time? By allowing devices to request firmware be loaded directly into a pre-allocated buffer, will this allow the device access to the firmware before the kernel has verified the firmware signature? Is it dependent on the type of buffer allocated (eg. DMA)? For example, qcom_mdt_load() -> qcom_scm_pas_init_image() -> dma_alloc_coherent(). With an IMA policy requiring signed firmware, this patch would prevent loading firmware into a pre-allocated buffer. Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com> Cc: Luis R. Rodriguez <mcgrof@suse.com> Cc: David Howells <dhowells@redhat.com> Cc: Kees Cook <keescook@chromium.org> Cc: Serge E. Hallyn <serge@hallyn.com> Cc: Stephen Boyd <stephen.boyd@linaro.org> --- security/integrity/ima/ima_main.c | 9 +++++++++ 1 file changed, 9 insertions(+)