[PATCH v2 7/9] ima: based on policy require signed firmware (sysfs fallback)

[Mimi Zohar]

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

Signed-off-by: Mimi Zohar <zo...@linux.vnet.ibm.com>
Cc: Luis R. Rodriguez <mcg...@suse.com>
Cc: David Howells <dhowe...@redhat.com>
Cc: Matthew Garrett <mj...@google.com>
---
 security/integrity/ima/ima_main.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/security/integrity/ima/ima_main.c 
b/security/integrity/ima/ima_main.c
index 7e1a127f18fe..29d1a929af5c 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -451,7 +451,17 @@ int ima_read_file(struct file *file, enum 
kernel_read_file_id read_id)
                }
                return 0;
        }
+
+       if (read_id == READING_FIRMWARE_FALLBACK_SYSFS) {
+               if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
+                   (ima_appraise & IMA_APPRAISE_ENFORCE)) {
+                       pr_err("Prevent firmware sysfs fallback loading.\n");
+                       return -EACCES;
+               }
+               return 0;
+       }
        return 0;
+
 }
 
 static int read_idmap[READING_MAX_ID] = {
-- 
2.7.5