ima: based on policy require signed firmware (sysfs fallback)

With an IMA policy requiring signed firmware, this patch prevents
the sysfs fallback method of loading firmware.

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Matthew Garrett <mjg59@google.com>
Signed-off-by: James Morris <james.morris@microsoft.com>

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 71fecfe..e467664 100644 (file)
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -472,8 +472,10 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
 
        if (!file && read_id == READING_FIRMWARE) {
                if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
-                   (ima_appraise & IMA_APPRAISE_ENFORCE))
+                   (ima_appraise & IMA_APPRAISE_ENFORCE)) {
+                       pr_err("Prevent firmware loading_store.\n");
                        return -EACCES; /* INTEGRITY_UNKNOWN */
+               }
                return 0;
        }
 
@@ -517,6 +519,12 @@ int ima_load_data(enum kernel_load_data_id id)
                        pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n");
                        return -EACCES; /* INTEGRITY_UNKNOWN */
                }
+               break;
+       case LOADING_FIRMWARE:
+               if (ima_appraise & IMA_APPRAISE_FIRMWARE) {
+                       pr_err("Prevent firmware sysfs fallback loading.\n");
+                       return -EACCES; /* INTEGRITY_UNKNOWN */
+               }
        default:
                break;
        }