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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <getopt.h>
#include <sd-messages.h>
#include "efivars.h"
#include "main-func.h"
#include "openssl-util.h"
#include "parse-util.h"
#include "pretty-print.h"
#include "tpm-pcr.h"
#include "tpm2-util.h"
static bool arg_graceful = false;
static char *arg_tpm2_device = NULL;
static char **arg_banks = NULL;
STATIC_DESTRUCTOR_REGISTER(arg_banks, strv_freep);
STATIC_DESTRUCTOR_REGISTER(arg_tpm2_device, freep);
static int help(int argc, char *argv[], void *userdata) {
_cleanup_free_ char *link = NULL;
int r;
r = terminal_urlify_man("systemd-pcrphase", "8", &link);
if (r < 0)
return log_oom();
printf("%1$s [OPTIONS...] WORD ...\n"
"\n%5$sMeasure boot phase into TPM2 PCR 11.%6$s\n"
"\n%3$sOptions:%4$s\n"
" -h --help Show this help\n"
" --version Print version\n"
" --bank=DIGEST Select TPM bank (SHA1, SHA256)\n"
" --tpm2-device=PATH Use specified TPM2 device\n"
" --graceful Exit gracefully if no TPM2 device is found\n"
"\nSee the %2$s for details.\n",
program_invocation_short_name,
link,
ansi_underline(),
ansi_normal(),
ansi_highlight(),
ansi_normal());
return 0;
}
static int parse_argv(int argc, char *argv[]) {
enum {
ARG_VERSION = 0x100,
ARG_BANK,
ARG_TPM2_DEVICE,
ARG_GRACEFUL,
};
static const struct option options[] = {
{ "help", no_argument, NULL, 'h' },
{ "version", no_argument, NULL, ARG_VERSION },
{ "bank", required_argument, NULL, ARG_BANK },
{ "tpm2-device", required_argument, NULL, ARG_TPM2_DEVICE },
{ "graceful", no_argument, NULL, ARG_GRACEFUL },
{}
};
int c;
assert(argc >= 0);
assert(argv);
while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
switch (c) {
case 'h':
help(0, NULL, NULL);
return 0;
case ARG_VERSION:
return version();
case ARG_BANK: {
const EVP_MD *implementation;
implementation = EVP_get_digestbyname(optarg);
if (!implementation)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Unknown bank '%s', refusing.", optarg);
if (strv_extend(&arg_banks, EVP_MD_name(implementation)) < 0)
return log_oom();
break;
}
case ARG_TPM2_DEVICE: {
_cleanup_free_ char *device = NULL;
if (streq(optarg, "list"))
return tpm2_list_devices();
if (!streq(optarg, "auto")) {
device = strdup(optarg);
if (!device)
return log_oom();
}
free_and_replace(arg_tpm2_device, device);
break;
}
case ARG_GRACEFUL:
arg_graceful = true;
break;
case '?':
return -EINVAL;
default:
assert_not_reached();
}
return 1;
}
static int determine_banks(struct tpm2_context *c) {
_cleanup_free_ TPMI_ALG_HASH *algs = NULL;
int n_algs, r;
assert(c);
if (!strv_isempty(arg_banks)) /* Explicitly configured? Then use that */
return 0;
n_algs = tpm2_get_good_pcr_banks(c->esys_context, UINT32_C(1) << TPM_PCR_INDEX_KERNEL_IMAGE, &algs);
if (n_algs <= 0)
return n_algs;
for (int i = 0; i < n_algs; i++) {
const EVP_MD *implementation;
const char *salg;
salg = tpm2_pcr_bank_to_string(algs[i]);
if (!salg)
return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "TPM2 operates with unknown PCR algorithm, can't measure.");
implementation = EVP_get_digestbyname(salg);
if (!implementation)
return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "TPM2 operates with unsupported PCR algorithm, can't measure.");
r = strv_extend(&arg_banks, EVP_MD_name(implementation));
if (r < 0)
return log_oom();
}
return 0;
}
static int run(int argc, char *argv[]) {
_cleanup_(tpm2_context_destroy) struct tpm2_context c = {};
_cleanup_free_ char *joined = NULL, *pcr_string = NULL;
const char *word;
unsigned pcr_nr;
size_t length;
TSS2_RC rc;
int r;
log_setup();
r = parse_argv(argc, argv);
if (r <= 0)
return r;
if (optind+1 != argc)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Expected a single argument.");
word = argv[optind];
/* Refuse to measure an empty word. We want to be able to write the series of measured words
* separated by colons, where multiple separating colons are collapsed. Thus it makes sense to
* disallow an empty word to avoid ambiguities. */
if (isempty(word))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "String to measure cannot be empty, refusing.");
if (arg_graceful && tpm2_support() != TPM2_SUPPORT_FULL) {
log_notice("No complete TPM2 support detected, exiting gracefully.");
return EXIT_SUCCESS;
}
length = strlen(word);
/* Skip logic if sd-stub is not used, after all PCR 11 might have a very different purpose then. */
r = efi_get_variable_string(EFI_LOADER_VARIABLE(StubPcrKernelImage), &pcr_string);
if (r == -ENOENT) {
log_info("Kernel stub did not measure kernel image into PCR %u, skipping measurement.", TPM_PCR_INDEX_KERNEL_IMAGE);
return EXIT_SUCCESS;
}
if (r < 0)
return log_error_errno(r, "Failed to read StubPcrKernelImage EFI variable: %m");
/* Let's validate that the stub announced PCR 11 as we expected. */
r = safe_atou(pcr_string, &pcr_nr);
if (r < 0)
return log_error_errno(r, "Failed to parse StubPcrKernelImage EFI variable: %s", pcr_string);
if (pcr_nr != TPM_PCR_INDEX_KERNEL_IMAGE)
return log_error_errno(SYNTHETIC_ERRNO(EREMOTE), "Kernel stub measured kernel image into PCR %u, which is different than expected %u.", pcr_nr, TPM_PCR_INDEX_KERNEL_IMAGE);
r = dlopen_tpm2();
if (r < 0)
return log_error_errno(r, "Failed to load TPM2 libraries: %m");
r = tpm2_context_init(arg_tpm2_device, &c);
if (r < 0)
return r;
r = determine_banks(&c);
if (r < 0)
return r;
if (strv_isempty(arg_banks)) /* Still none? */
return log_error_errno(SYNTHETIC_ERRNO(ENOENT), "Found a TPM2 without enabled PCR banks. Can't operate.");
TPML_DIGEST_VALUES values = {};
STRV_FOREACH(bank, arg_banks) {
const EVP_MD *implementation;
int id;
assert_se(implementation = EVP_get_digestbyname(*bank));
if (values.count >= ELEMENTSOF(values.digests))
return log_error_errno(SYNTHETIC_ERRNO(E2BIG), "Too many banks selected.");
if ((size_t) EVP_MD_size(implementation) > sizeof(values.digests[values.count].digest))
return log_error_errno(SYNTHETIC_ERRNO(E2BIG), "Hash result too large for TPM2.");
id = tpm2_pcr_bank_from_string(EVP_MD_name(implementation));
if (id < 0)
return log_error_errno(id, "Can't map hash name to TPM2.");
values.digests[values.count].hashAlg = id;
if (EVP_Digest(word, length, (unsigned char*) &values.digests[values.count].digest, NULL, implementation, NULL) != 1)
return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "Failed to hash word.");
values.count++;
}
joined = strv_join(arg_banks, ", ");
if (!joined)
return log_oom();
log_debug("Measuring '%s' into PCR index %u, banks %s.", word, TPM_PCR_INDEX_KERNEL_IMAGE, joined);
rc = sym_Esys_PCR_Extend(
c.esys_context,
ESYS_TR_PCR0 + TPM_PCR_INDEX_KERNEL_IMAGE, /* → PCR 11 */
ESYS_TR_PASSWORD,
ESYS_TR_NONE,
ESYS_TR_NONE,
&values);
if (rc != TSS2_RC_SUCCESS)
return log_error_errno(
SYNTHETIC_ERRNO(ENOTRECOVERABLE),
"Failed to measure '%s': %s",
word,
sym_Tss2_RC_Decode(rc));
log_struct(LOG_INFO,
"MESSAGE_ID=" SD_MESSAGE_TPM_PCR_EXTEND_STR,
LOG_MESSAGE("Successfully extended PCR index %u with '%s' (banks %s).", TPM_PCR_INDEX_KERNEL_IMAGE, word, joined),
"MEASURING=%s", word,
"PCR=%u", TPM_PCR_INDEX_KERNEL_IMAGE,
"BANKS=%s", joined);
return EXIT_SUCCESS;
}
DEFINE_MAIN_FUNCTION(run);
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