grub2/0131-tpm-Don-t-propagate-TPM-measurement-errors-to-the-ve.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Javier Martinez Canillas <javierm@redhat.com>
Date: Sat, 16 May 2020 11:33:18 +0200
Subject: [PATCH] tpm: Don't propagate TPM measurement errors to the verifiers
 layer

Currently if the EFI firmware fails to do a TPM measurement for a file,
the error will be propagated to the verifiers framework and so opening
the file will not succeed.

This mean that buggy firmwares will prevent the system to boot since the
loader won't be able to open any file. But failing to do TPM measurements
shouldn't be a fatal error and the system should still be able to boot.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
---
 grub-core/commands/tpm.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/grub-core/commands/tpm.c b/grub-core/commands/tpm.c
index 2052c36eab..e287d042e6 100644
--- a/grub-core/commands/tpm.c
+++ b/grub-core/commands/tpm.c
@@ -42,7 +42,8 @@ grub_tpm_verify_init (grub_file_t io,
 static grub_err_t
 grub_tpm_verify_write (void *context, void *buf, grub_size_t size)
 {
-  return grub_tpm_measure (buf, size, GRUB_BINARY_PCR, context);
+  grub_tpm_measure (buf, size, GRUB_BINARY_PCR, context);
+  return GRUB_ERR_NONE;
 }
 
 static grub_err_t
@@ -50,7 +51,6 @@ grub_tpm_verify_string (char *str, enum grub_verify_string_type type)
 {
   const char *prefix = NULL;
   char *description;
-  grub_err_t status;
 
   switch (type)
     {
@@ -66,15 +66,15 @@ grub_tpm_verify_string (char *str, enum grub_verify_string_type type)
     }
   description = grub_malloc (grub_strlen (str) + grub_strlen (prefix) + 1);
   if (!description)
-    return grub_errno;
+    return GRUB_ERR_NONE;
   grub_memcpy (description, prefix, grub_strlen (prefix));
   grub_memcpy (description + grub_strlen (prefix), str,
 	       grub_strlen (str) + 1);
-  status =
-    grub_tpm_measure ((unsigned char *) str, grub_strlen (str),
-		      GRUB_STRING_PCR, description);
+
+  grub_tpm_measure ((unsigned char *) str, grub_strlen (str), GRUB_STRING_PCR,
+                    description);
   grub_free (description);
-  return status;
+  return GRUB_ERR_NONE;
 }
 
 struct grub_file_verifier grub_tpm_verifier = {