From 415072bbda8b4de133c6dc6add230e41ee6d9579 Mon Sep 17 00:00:00 2001

From: Matthew Garrett <mjg59@coreos.com>

Date: Wed, 23 Mar 2016 17:03:43 -0700

Subject: [PATCH] Rework TPM measurements

Rework TPM measurements to use fewer PCRs. After discussion with upstream,

it's preferable to avoid using so many PCRs. Instead, measure into PCRs 8

and 9 but use a prefix in the event log to indicate which subsystem carried

out the measurements.

(cherry picked from commit bb3473d7c8741ad5ef7cf8aafbbcf094df08bfc9)

---

 grub-core/kern/dl.c                   |  2 +-

 grub-core/kern/tpm.c                  | 10 ++++++++--

 grub-core/lib/cmdline.c               |  4 ++--

 grub-core/loader/i386/efi/linux.c     |  4 ++--

 grub-core/loader/i386/linux.c         |  2 +-

 grub-core/loader/i386/multiboot_mbi.c |  2 +-

 grub-core/loader/i386/pc/linux.c      |  2 +-

 grub-core/loader/linux.c              |  2 +-

 grub-core/loader/multiboot.c          |  2 +-

 grub-core/loader/multiboot_mbi2.c     |  2 +-

 grub-core/script/execute.c            |  4 ++--

 include/grub/tpm.h                    |  9 +++------

 12 files changed, 24 insertions(+), 21 deletions(-)

diff --git a/grub-core/kern/dl.c b/grub-core/kern/dl.c

index 387d1e6446d..d0989573866 100644

--- a/grub-core/kern/dl.c

+++ b/grub-core/kern/dl.c

@@ -830,7 +830,7 @@ grub_dl_load_file (const char *filename)

      opens of the same device.  */

   grub_file_close (file);

-  grub_tpm_measure(core, size, GRUB_TPM_PCR, filename);

+  grub_tpm_measure(core, size, GRUB_BINARY_PCR, "grub_module", filename);

   mod = grub_dl_load_core (core, size);

   grub_free (core);

diff --git a/grub-core/kern/tpm.c b/grub-core/kern/tpm.c

index 1a991876c83..cb5a812035d 100644

--- a/grub-core/kern/tpm.c

+++ b/grub-core/kern/tpm.c

@@ -7,7 +7,13 @@

 grub_err_t

 grub_tpm_measure (unsigned char *buf, grub_size_t size, grub_uint8_t pcr,

-		  const char *description)

+		  const char *kind, const char *description)

 {

-  return grub_tpm_log_event(buf, size, pcr, description);

+  grub_err_t ret;

+  char *desc = grub_xasprintf("%s %s", kind, description);

+  if (!desc)

+    return GRUB_ERR_OUT_OF_MEMORY;

+  ret = grub_tpm_log_event(buf, size, pcr, description);

+  grub_free(desc);

+  return ret;

 }

diff --git a/grub-core/lib/cmdline.c b/grub-core/lib/cmdline.c

index 6b56304d4a7..178f7382f07 100644

--- a/grub-core/lib/cmdline.c

+++ b/grub-core/lib/cmdline.c

@@ -126,8 +126,8 @@ int grub_create_loader_cmdline (int argc, char *argv[], char *buf,

   *buf = 0;

-  grub_tpm_measure ((void *)orig, grub_strlen (orig), GRUB_CMDLINE_PCR,

-		    "Kernel Commandline");

+  grub_tpm_measure ((void *)orig, grub_strlen (orig), GRUB_ASCII_PCR,

+		    "grub_kernel_cmdline", orig);

   return i;

 }

diff --git a/grub-core/loader/i386/efi/linux.c b/grub-core/loader/i386/efi/linux.c

index 48febdc8100..079e222e972 100644

--- a/grub-core/loader/i386/efi/linux.c

+++ b/grub-core/loader/i386/efi/linux.c

@@ -133,7 +133,7 @@ grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),

                         argv[i]);

           goto fail;

         }

-      grub_tpm_measure (ptr, cursize, GRUB_INITRD_PCR, "UEFI Linux initrd");

+      grub_tpm_measure (ptr, cursize, GRUB_BINARY_PCR, "grub_linuxefi", "Initrd");

       ptr += cursize;

       grub_memset (ptr, 0, ALIGN_UP_OVERHEAD (cursize, 4));

       ptr += ALIGN_UP_OVERHEAD (cursize, 4);

@@ -198,7 +198,7 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),

       goto fail;

     }

-  grub_tpm_measure (kernel, filelen, GRUB_KERNEL_PCR, "UEFI Linux kernel");

+  grub_tpm_measure (kernel, filelen, GRUB_BINARY_PCR, "grub_linuxefi", "Kernel");

   rc = grub_linuxefi_secure_validate (kernel, filelen);

   if (rc < 0)

diff --git a/grub-core/loader/i386/linux.c b/grub-core/loader/i386/linux.c

index bc10add45a6..32e3bb08e88 100644

--- a/grub-core/loader/i386/linux.c

+++ b/grub-core/loader/i386/linux.c

@@ -719,7 +719,7 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),

       goto fail;

     }

-  grub_tpm_measure (kernel, len, GRUB_KERNEL_PCR, "Linux Kernel");

+  grub_tpm_measure (kernel, len, GRUB_BINARY_PCR, "grub_linux", "Kernel");

   grub_memcpy (&lh, kernel, sizeof (lh));

diff --git a/grub-core/loader/i386/multiboot_mbi.c b/grub-core/loader/i386/multiboot_mbi.c

index 5d00aed65ad..0981a2cfd93 100644

--- a/grub-core/loader/i386/multiboot_mbi.c

+++ b/grub-core/loader/i386/multiboot_mbi.c

@@ -174,7 +174,7 @@ grub_multiboot_load (grub_file_t file, const char *filename)

       return grub_errno;

     }

-  grub_tpm_measure((unsigned char*)buffer, len, GRUB_KERNEL_PCR, filename);

+  grub_tpm_measure((unsigned char*)buffer, len, GRUB_BINARY_PCR, "grub_multiboot", filename);

   header = find_header (buffer, len);

diff --git a/grub-core/loader/i386/pc/linux.c b/grub-core/loader/i386/pc/linux.c

index 6b8f365c9cf..7edbc5ea6c4 100644

--- a/grub-core/loader/i386/pc/linux.c

+++ b/grub-core/loader/i386/pc/linux.c

@@ -162,7 +162,7 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),

       goto fail;

     }

-  grub_tpm_measure (kernel, len, GRUB_KERNEL_PCR, "BIOS Linux Kernel");

+  grub_tpm_measure (kernel, len, GRUB_BINARY_PCR, "grub_linux16", "Kernel");

   grub_memcpy (&lh, kernel, sizeof (lh));

   kernel_offset = sizeof (lh);

diff --git a/grub-core/loader/linux.c b/grub-core/loader/linux.c

index 3005c0d19c9..78c41e33416 100644

--- a/grub-core/loader/linux.c

+++ b/grub-core/loader/linux.c

@@ -289,7 +289,7 @@ grub_initrd_load (struct grub_linux_initrd_context *initrd_ctx,

 	  grub_initrd_close (initrd_ctx);

 	  return grub_errno;

 	}

-      grub_tpm_measure (ptr, cursize, GRUB_INITRD_PCR, "Linux Initrd");

+      grub_tpm_measure (ptr, cursize, GRUB_BINARY_PCR, "grub_initrd", "Initrd");

       ptr += cursize;

     }

   if (newc)

diff --git a/grub-core/loader/multiboot.c b/grub-core/loader/multiboot.c

index 0ca525380c9..cc53d429bca 100644

--- a/grub-core/loader/multiboot.c

+++ b/grub-core/loader/multiboot.c

@@ -426,7 +426,7 @@ grub_cmd_module (grub_command_t cmd __attribute__ ((unused)),

     }

   grub_file_close (file);

-  grub_tpm_measure (module, size, GRUB_KERNEL_PCR, argv[0]);

+  grub_tpm_measure (module, size, GRUB_BINARY_PCR, "grub_multiboot", argv[0]);

   return GRUB_ERR_NONE;

 }

diff --git a/grub-core/loader/multiboot_mbi2.c b/grub-core/loader/multiboot_mbi2.c

index a7b4a57ec4f..f7e333f56c1 100644

--- a/grub-core/loader/multiboot_mbi2.c

+++ b/grub-core/loader/multiboot_mbi2.c

@@ -132,7 +132,7 @@ grub_multiboot_load (grub_file_t file, const char *filename)

   COMPILE_TIME_ASSERT (MULTIBOOT_HEADER_ALIGN % 4 == 0);

-  grub_tpm_measure ((unsigned char *)buffer, len, GRUB_KERNEL_PCR, filename);

+  grub_tpm_measure ((unsigned char *)mld.buffer, len, GRUB_BINARY_PCR, "grub_multiboot", filename);

   header = find_header (mld.buffer, len);

   if (header == 0)

diff --git a/grub-core/script/execute.c b/grub-core/script/execute.c

index 9ae04a05160..976643c47b0 100644

--- a/grub-core/script/execute.c

+++ b/grub-core/script/execute.c

@@ -995,8 +995,8 @@ grub_script_execute_cmdline (struct grub_script_cmd *cmd)

 				   argv.args[i]);

   }

   cmdstring[cmdlen-1]= '\0';

-  grub_tpm_measure ((unsigned char *)cmdstring, cmdlen, GRUB_COMMAND_PCR,

-		    cmdstring);

+  grub_tpm_measure ((unsigned char *)cmdstring, cmdlen, GRUB_ASCII_PCR,

+		    "grub_cmd", cmdstring);

   grub_free(cmdstring);

   invert = 0;

   argc = argv.argc - 1;

diff --git a/include/grub/tpm.h b/include/grub/tpm.h

index 7fc9d77d277..ecb2d09ff5d 100644

--- a/include/grub/tpm.h

+++ b/include/grub/tpm.h

@@ -26,11 +26,8 @@

 #define TPM_AUTHFAIL (TPM_BASE + 0x1)

 #define TPM_BADINDEX (TPM_BASE + 0x2)

-#define GRUB_TPM_PCR 9

-#define GRUB_KERNEL_PCR 10

-#define GRUB_INITRD_PCR 11

-#define GRUB_CMDLINE_PCR 12

-#define GRUB_COMMAND_PCR 13

+#define GRUB_ASCII_PCR 8

+#define GRUB_BINARY_PCR 9

 #define TPM_TAG_RQU_COMMAND 0x00C1

 #define TPM_ORD_Extend 0x14

@@ -70,7 +67,7 @@ typedef struct {

 } GRUB_PACKED ExtendOutgoing;

 grub_err_t EXPORT_FUNC(grub_tpm_measure) (unsigned char *buf, grub_size_t size,

-					  grub_uint8_t pcr,

+					  grub_uint8_t pcr, const char *kind,

 					  const char *description);

 #if defined (GRUB_MACHINE_EFI) || defined (GRUB_MACHINE_PCBIOS)

 grub_err_t grub_tpm_execute(PassThroughToTPM_InputParamBlock *inbuf,