diff options
Diffstat (limited to 'src/boot/pcrphase.c')
| -rw-r--r-- | src/boot/pcrphase.c | 275 |
1 files changed, 275 insertions, 0 deletions
diff --git a/src/boot/pcrphase.c b/src/boot/pcrphase.c new file mode 100644 index 0000000..2808ee8 --- /dev/null +++ b/src/boot/pcrphase.c @@ -0,0 +1,275 @@ +/* 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); |