From: Lee, Chun-Yi <joeyli.kernel@gmail.com>
Date: Tue, 13 Mar 2018 10:37:59 +0000 (+0800)
Subject: [PATCH 1/5] MODSIGN: do not load mok when secure boot disabled
X-Git-Tag: archive/raspbian/5.9.6-1+rpi1^2~24
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=91799a6c11e5341f11adea3e7978e13481a7ef58;p=linux.git

[PATCH 1/5] MODSIGN: do not load mok when secure boot disabled

Origin: https://lore.kernel.org/patchwork/patch/933173/

The mok can not be trusted when the secure boot is disabled. Which
means that the kernel embedded certificate is the only trusted key.

Due to db/dbx are authenticated variables, they needs manufacturer's
KEK for update. So db/dbx are secure when secureboot disabled.

Cc: David Howells <dhowells@redhat.com>
Cc: Josh Boyer <jwboyer@fedoraproject.org>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: "Lee, Chun-Yi" <jlee@suse.com>
[Rebased by Luca Boccassi]
[bwh: Forward-ported to 5.5.9:
 - get_cert_list() takes a pointer to status and returns the cert list
 - Adjust filename]

Gbp-Pq: Topic features/all/db-mok-keyring
Gbp-Pq: Name 0001-MODSIGN-do-not-load-mok-when-secure-boot-disabled.patch
---

diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c
index 253fb9a7fc9..64909c0868f 100644
--- a/security/integrity/platform_certs/load_uefi.c
+++ b/security/integrity/platform_certs/load_uefi.c
@@ -102,20 +102,6 @@ static int __init load_uefi_certs(void)
 		}
 	}
 
-	mok = get_cert_list(L"MokListRT", &mok_var, &moksize, &status);
-	if (!mok) {
-		if (status == EFI_NOT_FOUND)
-			pr_debug("MokListRT variable wasn't found\n");
-		else
-			pr_info("Couldn't get UEFI MokListRT\n");
-	} else {
-		rc = parse_efi_signature_list("UEFI:MokListRT",
-					      mok, moksize, get_handler_for_db);
-		if (rc)
-			pr_err("Couldn't parse MokListRT signatures: %d\n", rc);
-		kfree(mok);
-	}
-
 	dbx = get_cert_list(L"dbx", &secure_var, &dbxsize, &status);
 	if (!dbx) {
 		if (status == EFI_NOT_FOUND)
@@ -131,6 +117,24 @@ static int __init load_uefi_certs(void)
 		kfree(dbx);
 	}
 
+	/* the MOK can not be trusted when secure boot is disabled */
+	if (!efi_enabled(EFI_SECURE_BOOT))
+		return 0;
+
+	mok = get_cert_list(L"MokListRT", &mok_var, &moksize, &status);
+	if (!mok) {
+		if (status == EFI_NOT_FOUND)
+			pr_debug("MokListRT variable wasn't found\n");
+		else
+			pr_info("Couldn't get UEFI MokListRT\n");
+	} else {
+		rc = parse_efi_signature_list("UEFI:MokListRT",
+					      mok, moksize, get_handler_for_db);
+		if (rc)
+			pr_err("Couldn't parse MokListRT signatures: %d\n", rc);
+		kfree(mok);
+	}
+
 	return rc;
 }
 late_initcall(load_uefi_certs);