[PATCH v4 5/8] ima: based on policy require signed firmware (sysfs fallback)

Mimi Zohar
2018-05-29T18:02:33Z

Luis, is the security_kernel_post_read_file LSM hook in
firmware_loading_store() still needed after this patch? Should it be
calling security_kernel_load_data() instead?

---

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>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Matthew Garrett <mjg59@google.com>
---
security/integrity/ima/ima_main.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index a565d46084c2..4a87f78098c8 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -475,8 +475,10 @@ 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;
}

@@ -520,6 +522,12 @@ 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;
}
--
2.7.5