From bb3473d7c8741ad5ef7cf8aafbbcf094df08bfc9 Mon Sep 17 00:00:00 2001 From: Matthew Garrett 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. --- 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 794f9381d..7c76d3097 100644 --- a/grub-core/kern/dl.c +++ b/grub-core/kern/dl.c @@ -724,7 +724,7 @@ 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 1a991876c..cb5a81203 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 ac6e0b797..3791f3aa9 100644 --- a/grub-core/lib/cmdline.c +++ b/grub-core/lib/cmdline.c @@ -105,8 +105,8 @@ 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 32c20bc26..e89d466f6 100644 --- a/grub-core/loader/i386/efi/linux.c +++ b/grub-core/loader/i386/efi/linux.c @@ -169,7 +169,7 @@ 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); @@ -225,7 +225,7 @@ 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"); if (! grub_linuxefi_secure_validate (kernel, filelen)) { diff --git a/grub-core/loader/i386/linux.c b/grub-core/loader/i386/linux.c index 99005ae15..52769419f 100644 --- a/grub-core/loader/i386/linux.c +++ b/grub-core/loader/i386/linux.c @@ -718,7 +718,7 @@ 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 43a08e4b5..efaa66ce4 100644 --- a/grub-core/loader/i386/multiboot_mbi.c +++ b/grub-core/loader/i386/multiboot_mbi.c @@ -165,7 +165,7 @@ 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 bd73addba..b9dd80bb3 100644 --- a/grub-core/loader/i386/pc/linux.c +++ b/grub-core/loader/i386/pc/linux.c @@ -161,7 +161,7 @@ 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 3005c0d19..78c41e334 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 fe9a79ae0..05cd51154 100644 --- a/grub-core/loader/multiboot.c +++ b/grub-core/loader/multiboot.c @@ -385,7 +385,7 @@ 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 76c67c3b6..91f842bf7 100644 --- a/grub-core/loader/multiboot_mbi2.c +++ b/grub-core/loader/multiboot_mbi2.c @@ -127,7 +127,7 @@ 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 *)buffer, len, GRUB_BINARY_PCR, "grub_multiboot", filename); header = find_header (buffer, len); diff --git a/grub-core/script/execute.c b/grub-core/script/execute.c index 95c8b11d1..4852f1b59 100644 --- a/grub-core/script/execute.c +++ b/grub-core/script/execute.c @@ -961,8 +961,8 @@ 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 7fc9d77d2..ecb2d09ff 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,