Enforce module signatures in lockdown (rhbz #1696671)

efi-lockdown.patch

@@ -518,6 +518,109 @@ index f35ffdd096ad..2615669dbf03 100644
 -- 
 2.14.3
 
+From e5709852ca1e9ed443d9abebcb35cbc2f0d9d987 Mon Sep 17 00:00:00 2001
+From: David Howells <dhowells@redhat.com>
+Date: Mon, 18 Feb 2019 12:44:58 +0000
+Subject: [PATCH 02/27] Enforce module signatures if the kernel is locked down
+
+If the kernel is locked down, require that all modules have valid
+signatures that we can verify.
+
+I have adjusted the errors generated:
+
+ (1) If there's no signature (ENODATA) or we can't check it (ENOPKG,
+     ENOKEY), then:
+
+     (a) If signatures are enforced then EKEYREJECTED is returned.
+
+     (b) If there's no signature or we can't check it, but the kernel is
+	 locked down then EPERM is returned (this is then consistent with
+	 other lockdown cases).
+
+ (2) If the signature is unparseable (EBADMSG, EINVAL), the signature fails
+     the check (EKEYREJECTED) or a system error occurs (eg. ENOMEM), we
+     return the error we got.
+
+Note that the X.509 code doesn't check for key expiry as the RTC might not
+be valid or might not have been transferred to the kernel's clock yet.
+
+ [Modified by Matthew Garrett to remove the IMA integration. This will
+  be replaced with integration with the IMA architecture policy
+  patchset.]
+
+Signed-off-by: David Howells <dhowells@redhat.com>
+Reviewed-by: Jiri Bohac <jbohac@suse.cz>
+Signed-off-by: Matthew Garrett <matthewgarrett@google.com>
+Cc: Jessica Yu <jeyu@kernel.org>
+---
+ kernel/module.c | 39 ++++++++++++++++++++++++++++++++-------
+ 1 file changed, 32 insertions(+), 7 deletions(-)
+
+diff --git a/kernel/module.c b/kernel/module.c
+index 2ad1b5239910..9a377c6ea200 100644
+--- a/kernel/module.c
++++ b/kernel/module.c
+@@ -2767,8 +2767,9 @@ static inline void kmemleak_load_module(const struct module *mod,
+ #ifdef CONFIG_MODULE_SIG
+ static int module_sig_check(struct load_info *info, int flags)
+ {
+-	int err = -ENOKEY;
++	int err = -ENODATA;
+ 	const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1;
++	const char *reason;
+ 	const void *mod = info->hdr;
+ 
+ 	/*
+@@ -2783,16 +2784,40 @@ static int module_sig_check(struct load_info *info, int flags)
+ 		err = mod_verify_sig(mod, info);
+ 	}
+ 
+-	if (!err) {
++	switch (err) {
++	case 0:
+ 		info->sig_ok = true;
+ 		return 0;
+-	}
+ 
+-	/* Not having a signature is only an error if we're strict. */
+-	if (err == -ENOKEY && !is_module_sig_enforced())
+-		err = 0;
++		/* We don't permit modules to be loaded into trusted kernels
++		 * without a valid signature on them, but if we're not
++		 * enforcing, certain errors are non-fatal.
++		 */
++	case -ENODATA:
++		reason = "Loading of unsigned module";
++		goto decide;
++	case -ENOPKG:
++		reason = "Loading of module with unsupported crypto";
++		goto decide;
++	case -ENOKEY:
++		reason = "Loading of module with unavailable key";
++	decide:
++		if (is_module_sig_enforced()) {
++			pr_notice("%s is rejected\n", reason);
++			return -EKEYREJECTED;
++		}
+ 
+-	return err;
++		if (kernel_is_locked_down(reason))
++			return -EPERM;
++		return 0;
++
++		/* All other errors are fatal, including nomem, unparseable
++		 * signatures and signature check failures - even if signatures
++		 * aren't required.
++		 */
++	default:
++		return err;
++	}
+ }
+ #else /* !CONFIG_MODULE_SIG */
+ static int module_sig_check(struct load_info *info, int flags)
+-- 
+2.21.0
+
 From 7948946e19294e7560c81b177b2788d21ed79f59 Mon Sep 17 00:00:00 2001
 From: Matthew Garrett <mjg59@srcf.ucam.org>
 Date: Mon, 9 Apr 2018 09:52:46 +0100