File 0002-tpm-Disable-tpm-verifier-if-tpm-is-not-pre... of Package grub2

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File 0002-tpm-Disable-tpm-verifier-if-tpm-is-not-present.patch of Package grub2

From e5bba1012e34597215684aa948bbc30093faa750 Mon Sep 17 00:00:00 2001
From: Michael Chang <mchang@suse.com>
Date: Fri, 7 Oct 2022 13:37:10 +0800
Subject: [PATCH 2/2] tpm: Disable tpm verifier if tpm is not present

This helps to prevent out of memory error when reading large files via
disabling tpm device as verifier has to read all content into memory in
one chunk to measure the hash and extend to tpm.

For ibmvtpm driver support this change here would be needed. It helps to
prevent much memory consuming tpm subsystem from being activated when no
vtpm device present.

Signed-off-by: Michael Chang <mchang@suse.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
---
 grub-core/commands/efi/tpm.c          | 37 +++++++++++++++++++++++++++
 grub-core/commands/ieee1275/ibmvtpm.c | 16 +++++++-----
 grub-core/commands/tpm.c              |  4 +++
 include/grub/tpm.h                    |  1 +
 4 files changed, 52 insertions(+), 6 deletions(-)

diff --git a/grub-core/commands/efi/tpm.c b/grub-core/commands/efi/tpm.c
index c3f6e00d2..f68c1db1b 100644
--- a/grub-core/commands/efi/tpm.c
+++ b/grub-core/commands/efi/tpm.c
@@ -288,3 +288,40 @@ grub_tpm_measure (unsigned char *buf, grub_size_t size, grub_uint8_t pcr,
   else
     return grub_tpm2_log_event (tpm_handle, buf, size, pcr, description);
 }
+
+int
+grub_tpm_present (void)
+{
+  grub_efi_handle_t tpm_handle;
+  grub_efi_uint8_t protocol_version;
+
+  if (!grub_tpm_handle_find (&tpm_handle, &protocol_version))
+    return 0;
+
+  if (protocol_version == 1)
+    {
+      grub_efi_tpm_protocol_t *tpm;
+
+      tpm = grub_efi_open_protocol (tpm_handle, &tpm_guid,
+				    GRUB_EFI_OPEN_PROTOCOL_GET_PROTOCOL);
+      if (!tpm)
+	{
+	  grub_dprintf ("tpm", "Cannot open TPM protocol\n");
+	  return 0;
+	}
+      return grub_tpm1_present (tpm);
+    }
+  else
+    {
+      grub_efi_tpm2_protocol_t *tpm;
+
+      tpm = grub_efi_open_protocol (tpm_handle, &tpm2_guid,
+				    GRUB_EFI_OPEN_PROTOCOL_GET_PROTOCOL);
+      if (!tpm)
+	{
+	  grub_dprintf ("tpm", "Cannot open TPM protocol\n");
+	  return 0;
+	}
+      return grub_tpm2_present (tpm);
+    }
+}
diff --git a/grub-core/commands/ieee1275/ibmvtpm.c b/grub-core/commands/ieee1275/ibmvtpm.c
index e68b8448b..dec4ffec6 100644
--- a/grub-core/commands/ieee1275/ibmvtpm.c
+++ b/grub-core/commands/ieee1275/ibmvtpm.c
@@ -136,12 +136,6 @@ grub_err_t
 grub_tpm_measure (unsigned char *buf, grub_size_t size, grub_uint8_t pcr,
 		  const char *description)
 {
-  grub_err_t err = tpm_init();
-
-  /* Absence of a TPM isn't a failure. */
-  if (err != GRUB_ERR_NONE)
-    return GRUB_ERR_NONE;
-
   grub_dprintf ("tpm", "log_event, pcr = %d, size = 0x%" PRIxGRUB_SIZE ", %s\n",
 		pcr, size, description);
 
@@ -150,3 +144,13 @@ grub_tpm_measure (unsigned char *buf, grub_size_t size, grub_uint8_t pcr,
 
   return GRUB_ERR_NONE;
 }
+
+int
+grub_tpm_present (void)
+{
+  /*
+   * Call tpm_init() 'late' rather than from GRUB_MOD_INIT() so that device nodes
+   * can be found.
+   */
+  return tpm_init() == GRUB_ERR_NONE;
+}
diff --git a/grub-core/commands/tpm.c b/grub-core/commands/tpm.c
index 2052c36ea..cb8ed6b94 100644
--- a/grub-core/commands/tpm.c
+++ b/grub-core/commands/tpm.c
@@ -86,10 +86,14 @@ struct grub_file_verifier grub_tpm_verifier = {
 
 GRUB_MOD_INIT (tpm)
 {
+  if (!grub_tpm_present())
+    return;
   grub_verifier_register (&grub_tpm_verifier);
 }
 
 GRUB_MOD_FINI (tpm)
 {
+  if (!grub_tpm_present())
+    return;
   grub_verifier_unregister (&grub_tpm_verifier);
 }
diff --git a/include/grub/tpm.h b/include/grub/tpm.h
index 5c285cbc5..c19fcbd0a 100644
--- a/include/grub/tpm.h
+++ b/include/grub/tpm.h
@@ -36,4 +36,5 @@
 
 grub_err_t grub_tpm_measure (unsigned char *buf, grub_size_t size,
 			     grub_uint8_t pcr, const char *description);
+int grub_tpm_present (void);
 #endif
-- 
2.39.1

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