diff options
Diffstat (limited to 'src/boot/measure.c')
| -rw-r--r-- | src/boot/measure.c | 1164 |
1 files changed, 1164 insertions, 0 deletions
diff --git a/src/boot/measure.c b/src/boot/measure.c new file mode 100644 index 0000000..0bbd386 --- /dev/null +++ b/src/boot/measure.c @@ -0,0 +1,1164 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <getopt.h> +#include <unistd.h> + +#include "alloc-util.h" +#include "efi-loader.h" +#include "fd-util.h" +#include "fileio.h" +#include "hexdecoct.h" +#include "json.h" +#include "main-func.h" +#include "openssl-util.h" +#include "parse-argument.h" +#include "parse-util.h" +#include "pretty-print.h" +#include "sha256.h" +#include "terminal-util.h" +#include "tpm-pcr.h" +#include "tpm2-util.h" +#include "verbs.h" + +/* Tool for pre-calculating expected TPM PCR values based on measured resources. This is intended to be used + * to pre-calculate suitable values for PCR 11, the way sd-stub measures into it. */ + +static char *arg_sections[_UNIFIED_SECTION_MAX] = {}; +static char **arg_banks = NULL; +static char *arg_tpm2_device = NULL; +static char *arg_private_key = NULL; +static char *arg_public_key = NULL; +static JsonFormatFlags arg_json_format_flags = JSON_FORMAT_PRETTY_AUTO|JSON_FORMAT_COLOR_AUTO|JSON_FORMAT_OFF; +static PagerFlags arg_pager_flags = 0; +static bool arg_current = false; +static char **arg_phase = NULL; + +STATIC_DESTRUCTOR_REGISTER(arg_banks, strv_freep); +STATIC_DESTRUCTOR_REGISTER(arg_tpm2_device, freep); +STATIC_DESTRUCTOR_REGISTER(arg_private_key, freep); +STATIC_DESTRUCTOR_REGISTER(arg_public_key, freep); +STATIC_DESTRUCTOR_REGISTER(arg_phase, strv_freep); + +static inline void free_sections(char*(*sections)[_UNIFIED_SECTION_MAX]) { + for (UnifiedSection c = 0; c < _UNIFIED_SECTION_MAX; c++) + free((*sections)[c]); +} + +STATIC_DESTRUCTOR_REGISTER(arg_sections, free_sections); + +static int help(int argc, char *argv[], void *userdata) { + _cleanup_free_ char *link = NULL; + int r; + + r = terminal_urlify_man("systemd-measure", "1", &link); + if (r < 0) + return log_oom(); + + printf("%1$s [OPTIONS...] COMMAND ...\n" + "\n%5$sPre-calculate and sign PCR hash for a unified kernel image (UKI).%6$s\n" + "\n%3$sCommands:%4$s\n" + " status Show current PCR values\n" + " calculate Calculate expected PCR values\n" + " sign Calculate and sign expected PCR values\n" + "\n%3$sOptions:%4$s\n" + " -h --help Show this help\n" + " --version Print version\n" + " --no-pager Do not pipe output into a pager\n" + " -c --current Use current PCR values\n" + " --phase=PHASE Specify a boot phase to sign for\n" + " --bank=DIGEST Select TPM bank (SHA1, SHA256, SHA384, SHA512)\n" + " --tpm2-device=PATH Use specified TPM2 device\n" + " --private-key=KEY Private key (PEM) to sign with\n" + " --public-key=KEY Public key (PEM) to validate against\n" + " --json=MODE Output as JSON\n" + " -j Same as --json=pretty on tty, --json=short otherwise\n" + "\n%3$sUKI PE Section Options:%4$s %3$sUKI PE Section%4$s\n" + " --linux=PATH Path to Linux kernel image file %7$s .linux\n" + " --osrel=PATH Path to os-release file %7$s .osrel\n" + " --cmdline=PATH Path to file with kernel command line %7$s .cmdline\n" + " --initrd=PATH Path to initrd image file %7$s .initrd\n" + " --splash=PATH Path to splash bitmap file %7$s .splash\n" + " --dtb=PATH Path to Devicetree file %7$s .dtb\n" + " --pcrpkey=PATH Path to public key for PCR signatures %7$s .pcrpkey\n" + "\nSee the %2$s for details.\n", + program_invocation_short_name, + link, + ansi_underline(), + ansi_normal(), + ansi_highlight(), + ansi_normal(), + special_glyph(SPECIAL_GLYPH_ARROW_RIGHT)); + + return 0; +} + +static char *normalize_phase(const char *s) { + _cleanup_strv_free_ char **l = NULL; + + /* Let's normalize phase expressions. We split the series of colon-separated words up, then remove + * all empty ones, and glue them back together again. In other words we remove duplicate ":", as well + * as leading and trailing ones. */ + + l = strv_split(s, ":"); /* Split series of words */ + if (!l) + return NULL; + + /* Remove all empty words and glue things back together */ + return strv_join(strv_remove(l, ""), ":"); +} + +static int parse_argv(int argc, char *argv[]) { + enum { + ARG_VERSION = 0x100, + ARG_NO_PAGER, + _ARG_SECTION_FIRST, + ARG_LINUX = _ARG_SECTION_FIRST, + ARG_OSREL, + ARG_CMDLINE, + ARG_INITRD, + ARG_SPLASH, + ARG_DTB, + _ARG_PCRSIG, /* the .pcrsig section is not input for signing, hence not actually an argument here */ + _ARG_SECTION_LAST, + ARG_PCRPKEY = _ARG_SECTION_LAST, + ARG_BANK, + ARG_PRIVATE_KEY, + ARG_PUBLIC_KEY, + ARG_TPM2_DEVICE, + ARG_JSON, + ARG_PHASE, + }; + + static const struct option options[] = { + { "help", no_argument, NULL, 'h' }, + { "no-pager", no_argument, NULL, ARG_NO_PAGER }, + { "version", no_argument, NULL, ARG_VERSION }, + { "linux", required_argument, NULL, ARG_LINUX }, + { "osrel", required_argument, NULL, ARG_OSREL }, + { "cmdline", required_argument, NULL, ARG_CMDLINE }, + { "initrd", required_argument, NULL, ARG_INITRD }, + { "splash", required_argument, NULL, ARG_SPLASH }, + { "dtb", required_argument, NULL, ARG_DTB }, + { "pcrpkey", required_argument, NULL, ARG_PCRPKEY }, + { "current", no_argument, NULL, 'c' }, + { "bank", required_argument, NULL, ARG_BANK }, + { "tpm2-device", required_argument, NULL, ARG_TPM2_DEVICE }, + { "private-key", required_argument, NULL, ARG_PRIVATE_KEY }, + { "public-key", required_argument, NULL, ARG_PUBLIC_KEY }, + { "json", required_argument, NULL, ARG_JSON }, + { "phase", required_argument, NULL, ARG_PHASE }, + {} + }; + + int c, r; + + assert(argc >= 0); + assert(argv); + + /* Make sure the arguments list and the section list, stays in sync */ + assert_cc(_ARG_SECTION_FIRST + _UNIFIED_SECTION_MAX == _ARG_SECTION_LAST + 1); + + while ((c = getopt_long(argc, argv, "hjc", options, NULL)) >= 0) + switch (c) { + + case 'h': + help(0, NULL, NULL); + return 0; + + case ARG_VERSION: + return version(); + + case ARG_NO_PAGER: + arg_pager_flags |= PAGER_DISABLE; + break; + + case _ARG_SECTION_FIRST..._ARG_SECTION_LAST: { + UnifiedSection section = c - _ARG_SECTION_FIRST; + + r = parse_path_argument(optarg, /* suppress_root= */ false, arg_sections + section); + if (r < 0) + return r; + break; + } + + case 'c': + arg_current = true; + break; + + 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_PRIVATE_KEY: + r = parse_path_argument(optarg, /* suppress_root= */ false, &arg_private_key); + if (r < 0) + return r; + + break; + + case ARG_PUBLIC_KEY: + r = parse_path_argument(optarg, /* suppress_root= */ false, &arg_public_key); + if (r < 0) + return r; + + 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 'j': + arg_json_format_flags = JSON_FORMAT_PRETTY_AUTO|JSON_FORMAT_COLOR_AUTO; + break; + + case ARG_JSON: + r = parse_json_argument(optarg, &arg_json_format_flags); + if (r <= 0) + return r; + + break; + + case ARG_PHASE: { + char *n; + + n = normalize_phase(optarg); + if (!n) + return log_oom(); + + r = strv_consume(&arg_phase, TAKE_PTR(n)); + if (r < 0) + return r; + + break; + } + + case '?': + return -EINVAL; + + default: + assert_not_reached(); + } + + if (strv_isempty(arg_banks)) { + /* If no banks are specifically selected, pick all known banks */ + arg_banks = strv_new("SHA1", "SHA256", "SHA384", "SHA512"); + if (!arg_banks) + return log_oom(); + } + + strv_sort(arg_banks); + strv_uniq(arg_banks); + + if (arg_current) + for (UnifiedSection us = 0; us < _UNIFIED_SECTION_MAX; us++) + if (arg_sections[us]) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "The --current switch cannot be used in combination with --linux= and related switches."); + + if (strv_isempty(arg_phase)) { + /* If no phases are specifically selected, pick everything from the beginning of the initrd + * to the beginning of shutdown. */ + if (strv_extend_strv(&arg_phase, + STRV_MAKE("enter-initrd", + "enter-initrd:leave-initrd", + "enter-initrd:leave-initrd:sysinit", + "enter-initrd:leave-initrd:sysinit:ready"), + /* filter_duplicates= */ false) < 0) + return log_oom(); + } else { + strv_sort(arg_phase); + strv_uniq(arg_phase); + } + + _cleanup_free_ char *j = NULL; + j = strv_join(arg_phase, ", "); + if (!j) + return log_oom(); + + log_debug("Measuring boot phases: %s", j); + return 1; +} + +/* The PCR 11 state for one specific bank */ +typedef struct PcrState { + char *bank; + const EVP_MD *md; + void *value; + size_t value_size; + void *saved_value; /* A copy of the original value we calculated, used by pcr_states_save()/pcr_states_restore() to come later back to */ +} PcrState; + +static void pcr_state_free_all(PcrState **pcr_state) { + assert(pcr_state); + + if (!*pcr_state) + return; + + for (size_t i = 0; (*pcr_state)[i].value; i++) { + free((*pcr_state)[i].bank); + free((*pcr_state)[i].value); + free((*pcr_state)[i].saved_value); + } + + *pcr_state = mfree(*pcr_state); +} + +static void evp_md_ctx_free_all(EVP_MD_CTX **md[]) { + assert(md); + + if (!*md) + return; + + for (size_t i = 0; (*md)[i]; i++) + EVP_MD_CTX_free((*md)[i]); + + *md = mfree(*md); +} + +static int pcr_state_extend(PcrState *pcr_state, const void *data, size_t sz) { + _cleanup_(EVP_MD_CTX_freep) EVP_MD_CTX *mc = NULL; + unsigned value_size; + + assert(pcr_state); + assert(data || sz == 0); + assert(pcr_state->md); + assert(pcr_state->value); + assert(pcr_state->value_size > 0); + + /* Extends a (virtual) PCR by the given data */ + + mc = EVP_MD_CTX_new(); + if (!mc) + return log_oom(); + + if (EVP_DigestInit_ex(mc, pcr_state->md, NULL) != 1) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to initialize %s context.", pcr_state->bank); + + /* First thing we do, is hash the old PCR value */ + if (EVP_DigestUpdate(mc, pcr_state->value, pcr_state->value_size) != 1) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to run digest."); + + /* Then, we hash the new data */ + if (EVP_DigestUpdate(mc, data, sz) != 1) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to run digest."); + + if (EVP_DigestFinal_ex(mc, pcr_state->value, &value_size) != 1) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to finalize hash context."); + + assert(value_size == pcr_state->value_size); + return 0; +} + +#define BUFFER_SIZE (16U * 1024U) + +static int measure_kernel(PcrState *pcr_states, size_t n) { + _cleanup_free_ void *buffer = NULL; + int r; + + assert(n > 0); + assert(pcr_states); + + /* Virtually measures the components of a unified kernel image into PCR 11 */ + + if (arg_current) { + /* Shortcut things, if we should just use the current PCR value */ + + for (size_t i = 0; i < n; i++) { + _cleanup_free_ char *p = NULL, *s = NULL; + _cleanup_free_ void *v = NULL; + size_t sz; + + if (asprintf(&p, "/sys/class/tpm/tpm0/pcr-%s/%" PRIu32, pcr_states[i].bank, TPM_PCR_INDEX_KERNEL_IMAGE) < 0) + return log_oom(); + + r = read_virtual_file(p, 4096, &s, NULL); + if (r == -ENOENT && access("/sys/class/tpm/tpm0/", F_OK) >= 0) + return log_error_errno(r, "TPM device exists, but cannot open '%s'; either the kernel is too old, or selected PCR bank is not supported: %m", p); + if (r < 0) + return log_error_errno(r, "Failed to read '%s': %m", p); + + r = unhexmem(strstrip(s), SIZE_MAX, &v, &sz); + if (r < 0) + return log_error_errno(r, "Failed to decode PCR value '%s': %m", s); + + assert(pcr_states[i].value_size == sz); + memcpy(pcr_states[i].value, v, sz); + } + + return 0; + } + + buffer = malloc(BUFFER_SIZE); + if (!buffer) + return log_oom(); + + for (UnifiedSection c = 0; c < _UNIFIED_SECTION_MAX; c++) { + _cleanup_(evp_md_ctx_free_all) EVP_MD_CTX **mdctx = NULL; + _cleanup_close_ int fd = -1; + uint64_t m = 0; + + if (!arg_sections[c]) + continue; + + fd = open(arg_sections[c], O_RDONLY|O_CLOEXEC); + if (fd < 0) + return log_error_errno(errno, "Failed to open '%s': %m", arg_sections[c]); + + /* Allocate one message digest context per bank (NULL terminated) */ + mdctx = new0(EVP_MD_CTX*, n + 1); + if (!mdctx) + return log_oom(); + + for (size_t i = 0; i < n; i++) { + mdctx[i] = EVP_MD_CTX_new(); + if (!mdctx[i]) + return log_oom(); + + if (EVP_DigestInit_ex(mdctx[i], pcr_states[i].md, NULL) != 1) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to initialize data %s context.", pcr_states[i].bank); + } + + for (;;) { + ssize_t sz; + + sz = read(fd, buffer, BUFFER_SIZE); + if (sz < 0) + return log_error_errno(errno, "Failed to read '%s': %m", arg_sections[c]); + if (sz == 0) /* EOF */ + break; + + for (size_t i = 0; i < n; i++) + if (EVP_DigestUpdate(mdctx[i], buffer, sz) != 1) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to run digest."); + + m += sz; + } + + fd = safe_close(fd); + + if (m == 0) /* We skip over empty files, the stub does so too */ + continue; + + for (size_t i = 0; i < n; i++) { + _cleanup_free_ void *data_hash = NULL; + unsigned data_hash_size; + + data_hash = malloc(pcr_states[i].value_size); + if (!data_hash) + return log_oom(); + + /* Measure name of section */ + if (EVP_Digest(unified_sections[c], strlen(unified_sections[c]) + 1, data_hash, &data_hash_size, pcr_states[i].md, NULL) != 1) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to hash section name with %s.", pcr_states[i].bank); + + assert(data_hash_size == (unsigned) pcr_states[i].value_size); + + r = pcr_state_extend(pcr_states + i, data_hash, data_hash_size); + if (r < 0) + return r; + + /* Retrieve hash of data and measure it */ + if (EVP_DigestFinal_ex(mdctx[i], data_hash, &data_hash_size) != 1) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to finalize hash context."); + + assert(data_hash_size == (unsigned) pcr_states[i].value_size); + + r = pcr_state_extend(pcr_states + i, data_hash, data_hash_size); + if (r < 0) + return r; + } + } + + return 0; +} + +static int measure_phase(PcrState *pcr_states, size_t n, const char *phase) { + _cleanup_strv_free_ char **l = NULL; + int r; + + assert(pcr_states); + assert(n > 0); + + /* Measure a phase string into PCR 11. This splits up the "phase" expression at colons, and then + * virtually extends each specified word into PCR 11, to model how during boot we measure a series of + * words into PCR 11, one for each phase. */ + + l = strv_split(phase, ":"); + if (!l) + return log_oom(); + + STRV_FOREACH(word, l) { + size_t wl; + + if (isempty(*word)) + continue; + + wl = strlen(*word); + + for (size_t i = 0; i < n; i++) { /* For each bank */ + _cleanup_free_ void *b = NULL; + int bsz; + + bsz = EVP_MD_size(pcr_states[i].md); + assert(bsz > 0); + + b = malloc(bsz); + if (!b) + return log_oom(); + + /* First hash the word itself */ + if (EVP_Digest(*word, wl, b, NULL, pcr_states[i].md, NULL) != 1) + return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "Failed to hash word '%s'.", *word); + + /* And then extend the PCR with the resulting hash */ + r = pcr_state_extend(pcr_states + i, b, bsz); + if (r < 0) + return r; + } + } + + return 0; +} + +static int pcr_states_allocate(PcrState **ret) { + _cleanup_(pcr_state_free_all) PcrState *pcr_states = NULL; + size_t n = 0; + + pcr_states = new0(PcrState, strv_length(arg_banks) + 1); + if (!pcr_states) + return log_oom(); + + /* Allocate a PCR state structure, one for each bank */ + STRV_FOREACH(d, arg_banks) { + const EVP_MD *implementation; + _cleanup_free_ void *v = NULL; + _cleanup_free_ char *b = NULL; + int sz; + + assert_se(implementation = EVP_get_digestbyname(*d)); /* Must work, we already checked while parsing command line */ + + b = strdup(EVP_MD_name(implementation)); + if (!b) + return log_oom(); + + sz = EVP_MD_size(implementation); + if (sz <= 0 || sz >= INT_MAX) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Unexpected digest size: %i", sz); + + v = malloc0(sz); /* initial PCR state is all zeroes */ + if (!v) + return log_oom(); + + pcr_states[n++] = (struct PcrState) { + .bank = ascii_strlower(TAKE_PTR(b)), + .md = implementation, + .value = TAKE_PTR(v), + .value_size = sz, + }; + } + + *ret = TAKE_PTR(pcr_states); + return (int) n; +} + +static int pcr_states_save(PcrState *pcr_states, size_t n) { + assert(pcr_states); + assert(n > 0); + + for (size_t i = 0; i < n; i++) { + _cleanup_free_ void *saved = NULL; + + if (!pcr_states[i].value) + continue; + + saved = memdup(pcr_states[i].value, pcr_states[i].value_size); + if (!saved) + return log_oom(); + + free_and_replace(pcr_states[i].saved_value, saved); + } + + return 0; +} + +static void pcr_states_restore(PcrState *pcr_states, size_t n) { + assert(pcr_states); + assert(n > 0); + + for (size_t i = 0; i < n; i++) { + + assert(pcr_states[i].value); + assert(pcr_states[i].saved_value); + + memcpy(pcr_states[i].value, pcr_states[i].saved_value, pcr_states[i].value_size); + } +} + +static int verb_calculate(int argc, char *argv[], void *userdata) { + _cleanup_(json_variant_unrefp) JsonVariant *w = NULL; + _cleanup_(pcr_state_free_all) PcrState *pcr_states = NULL; + size_t n; + int r; + + if (!arg_sections[UNIFIED_SECTION_LINUX] && !arg_current) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Either --linux= or --current must be specified, refusing."); + + assert(!strv_isempty(arg_banks)); + assert(!strv_isempty(arg_phase)); + + r = pcr_states_allocate(&pcr_states); + if (r < 0) + return r; + + n = (size_t) r; + + r = measure_kernel(pcr_states, n); + if (r < 0) + return r; + + /* Save the current state, so that we later can restore to it. This way we can measure the PCR values + * for multiple different boot phases without heaving to start from zero each time */ + r = pcr_states_save(pcr_states, n); + if (r < 0) + return r; + + STRV_FOREACH(phase, arg_phase) { + + r = measure_phase(pcr_states, n, *phase); + if (r < 0) + return r; + + for (size_t i = 0; i < n; i++) { + if (arg_json_format_flags & JSON_FORMAT_OFF) { + _cleanup_free_ char *hd = NULL; + + if (i == 0) { + fflush(stdout); + fprintf(stderr, "%s# PCR[%" PRIu32 "] Phase <%s>%s\n", + ansi_grey(), + TPM_PCR_INDEX_KERNEL_IMAGE, + isempty(*phase) ? ":" : *phase, + ansi_normal()); + fflush(stderr); + } + + hd = hexmem(pcr_states[i].value, pcr_states[i].value_size); + if (!hd) + return log_oom(); + + printf("%" PRIu32 ":%s=%s\n", TPM_PCR_INDEX_KERNEL_IMAGE, pcr_states[i].bank, hd); + } else { + _cleanup_(json_variant_unrefp) JsonVariant *bv = NULL, *array = NULL; + + array = json_variant_ref(json_variant_by_key(w, pcr_states[i].bank)); + + r = json_build(&bv, + JSON_BUILD_OBJECT( + JSON_BUILD_PAIR_CONDITION(!isempty(*phase), "phase", JSON_BUILD_STRING(*phase)), + JSON_BUILD_PAIR("pcr", JSON_BUILD_INTEGER(TPM_PCR_INDEX_KERNEL_IMAGE)), + JSON_BUILD_PAIR("hash", JSON_BUILD_HEX(pcr_states[i].value, pcr_states[i].value_size)) + ) + ); + if (r < 0) + return log_error_errno(r, "Failed to build JSON object: %m"); + + r = json_variant_append_array(&array, bv); + if (r < 0) + return log_error_errno(r, "Failed to append JSON object to array: %m"); + + r = json_variant_set_field(&w, pcr_states[i].bank, array); + if (r < 0) + return log_error_errno(r, "Failed to add bank info to object: %m"); + } + } + + /* Return to the original kernel measurement for the next phase calculation */ + pcr_states_restore(pcr_states, n); + } + + if (!FLAGS_SET(arg_json_format_flags, JSON_FORMAT_OFF)) { + + if (arg_json_format_flags & (JSON_FORMAT_PRETTY|JSON_FORMAT_PRETTY_AUTO)) + pager_open(arg_pager_flags); + + json_variant_dump(w, arg_json_format_flags, stdout, NULL); + } + + return 0; +} + +static int verb_sign(int argc, char *argv[], void *userdata) { + _cleanup_(json_variant_unrefp) JsonVariant *v = NULL; + _cleanup_(pcr_state_free_all) PcrState *pcr_states = NULL; + _cleanup_(EVP_PKEY_freep) EVP_PKEY *privkey = NULL, *pubkey = NULL; + _cleanup_(tpm2_context_destroy) struct tpm2_context c = {}; + _cleanup_fclose_ FILE *privkeyf = NULL; + ESYS_TR session_handle = ESYS_TR_NONE; + TSS2_RC rc; + size_t n; + int r; + + if (!arg_sections[UNIFIED_SECTION_LINUX] && !arg_current) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Either --linux= or --current must be specified, refusing."); + + if (!arg_private_key) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "No private key specified, use --private-key=."); + + assert(!strv_isempty(arg_banks)); + assert(!strv_isempty(arg_phase)); + + /* When signing we only support JSON output */ + arg_json_format_flags &= ~JSON_FORMAT_OFF; + + privkeyf = fopen(arg_private_key, "re"); + if (!privkeyf) + return log_error_errno(errno, "Failed to open private key file '%s': %m", arg_private_key); + + privkey = PEM_read_PrivateKey(privkeyf, NULL, NULL, NULL); + if (!privkey) + return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to parse private key '%s'.", arg_private_key); + + if (arg_public_key) { + _cleanup_fclose_ FILE *pubkeyf = NULL; + + pubkeyf = fopen(arg_public_key, "re"); + if (!pubkeyf) + return log_error_errno(errno, "Failed to open public key file '%s': %m", arg_public_key); + + pubkey = PEM_read_PUBKEY(pubkeyf, NULL, NULL, NULL); + if (!pubkey) + return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to parse public key '%s'.", arg_public_key); + } else { + _cleanup_free_ char *data = NULL; + _cleanup_fclose_ FILE *tf = NULL; + size_t sz; + + /* No public key was specified, let's derive it automatically, if we can */ + + tf = open_memstream_unlocked(&data, &sz); + if (!tf) + return log_oom(); + + if (i2d_PUBKEY_fp(tf, privkey) != 1) + return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to extract public key from private key file '%s'.", arg_private_key); + + fflush(tf); + rewind(tf); + + if (!d2i_PUBKEY_fp(tf, &pubkey)) + return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to parse extracted public key of private key file '%s'.", arg_private_key); + } + + r = pcr_states_allocate(&pcr_states); + if (r < 0) + return r; + + n = (size_t) r; + + r = measure_kernel(pcr_states, n); + if (r < 0) + return r; + + r = pcr_states_save(pcr_states, n); + if (r < 0) + return r; + + r = dlopen_tpm2(); + if (r < 0) + return r; + + r = tpm2_context_init(arg_tpm2_device, &c); + if (r < 0) + return r; + + STRV_FOREACH(phase, arg_phase) { + + r = measure_phase(pcr_states, n, *phase); + if (r < 0) + return r; + + for (size_t i = 0; i < n; i++) { + static const TPMT_SYM_DEF symmetric = { + .algorithm = TPM2_ALG_AES, + .keyBits.aes = 128, + .mode.aes = TPM2_ALG_CFB, + }; + PcrState *p = pcr_states + i; + + rc = sym_Esys_StartAuthSession( + c.esys_context, + ESYS_TR_NONE, + ESYS_TR_NONE, + ESYS_TR_NONE, + ESYS_TR_NONE, + ESYS_TR_NONE, + NULL, + TPM2_SE_TRIAL, + &symmetric, + TPM2_ALG_SHA256, + &session_handle); + if (rc != TSS2_RC_SUCCESS) { + r = log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), + "Failed to open session in TPM: %s", sym_Tss2_RC_Decode(rc)); + goto finish; + } + + /* Generate a single hash value from the PCRs included in our policy. Given that that's + * exactly one, the calculation is trivial. */ + TPM2B_DIGEST intermediate_digest = { + .size = SHA256_DIGEST_SIZE, + }; + assert(sizeof(intermediate_digest.buffer) >= SHA256_DIGEST_SIZE); + sha256_direct(p->value, p->value_size, intermediate_digest.buffer); + + int tpmalg = tpm2_pcr_bank_from_string(EVP_MD_name(p->md)); + if (tpmalg < 0) { + log_error_errno(tpmalg, "Unsupported PCR bank"); + goto finish; + } + + TPML_PCR_SELECTION pcr_selection; + tpm2_pcr_mask_to_selection(1 << TPM_PCR_INDEX_KERNEL_IMAGE, tpmalg, &pcr_selection); + + rc = sym_Esys_PolicyPCR( + c.esys_context, + session_handle, + ESYS_TR_NONE, + ESYS_TR_NONE, + ESYS_TR_NONE, + &intermediate_digest, + &pcr_selection); + if (rc != TSS2_RC_SUCCESS) { + r = log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), + "Failed to push PCR policy into TPM: %s", sym_Tss2_RC_Decode(rc)); + goto finish; + } + + _cleanup_(Esys_Freep) TPM2B_DIGEST *pcr_policy_digest = NULL; + rc = sym_Esys_PolicyGetDigest( + c.esys_context, + session_handle, + ESYS_TR_NONE, + ESYS_TR_NONE, + ESYS_TR_NONE, + &pcr_policy_digest); + if (rc != TSS2_RC_SUCCESS) { + r = log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), + "Failed to get policy digest from TPM: %s", sym_Tss2_RC_Decode(rc)); + goto finish; + } + + session_handle = tpm2_flush_context_verbose(c.esys_context, session_handle); + + _cleanup_(EVP_MD_CTX_freep) EVP_MD_CTX* mdctx = NULL; + mdctx = EVP_MD_CTX_new(); + if (!mdctx) { + r = log_oom(); + goto finish; + } + + if (EVP_DigestSignInit(mdctx, NULL, p->md, NULL, privkey) != 1) { + r = log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), + "Failed to initialize signature context."); + goto finish; + } + + if (EVP_DigestSignUpdate(mdctx, pcr_policy_digest->buffer, pcr_policy_digest->size) != 1) { + r = log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), + "Failed to sign data."); + goto finish; + } + + size_t ss; + if (EVP_DigestSignFinal(mdctx, NULL, &ss) != 1) { + r = log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), + "Failed to finalize signature"); + goto finish; + } + + _cleanup_free_ void *sig = malloc(ss); + if (!sig) { + r = log_oom(); + goto finish; + } + + if (EVP_DigestSignFinal(mdctx, sig, &ss) != 1) { + r = log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), + "Failed to acquire signature data"); + goto finish; + } + + _cleanup_free_ void *pubkey_fp = NULL; + size_t pubkey_fp_size = 0; + r = pubkey_fingerprint(pubkey, EVP_sha256(), &pubkey_fp, &pubkey_fp_size); + if (r < 0) + goto finish; + + _cleanup_(json_variant_unrefp) JsonVariant *a = NULL; + r = tpm2_make_pcr_json_array(UINT64_C(1) << TPM_PCR_INDEX_KERNEL_IMAGE, &a); + if (r < 0) { + log_error_errno(r, "Failed to build JSON PCR mask array: %m"); + goto finish; + } + + _cleanup_(json_variant_unrefp) JsonVariant *bv = NULL; + r = json_build(&bv, JSON_BUILD_OBJECT( + JSON_BUILD_PAIR("pcrs", JSON_BUILD_VARIANT(a)), /* PCR mask */ + JSON_BUILD_PAIR("pkfp", JSON_BUILD_HEX(pubkey_fp, pubkey_fp_size)), /* SHA256 fingerprint of public key (DER) used for the signature */ + JSON_BUILD_PAIR("pol", JSON_BUILD_HEX(pcr_policy_digest->buffer, pcr_policy_digest->size)), /* TPM2 policy hash that is signed */ + JSON_BUILD_PAIR("sig", JSON_BUILD_BASE64(sig, ss)))); /* signature data */ + if (r < 0) { + log_error_errno(r, "Failed to build JSON object: %m"); + goto finish; + } + + _cleanup_(json_variant_unrefp) JsonVariant *av = NULL; + av = json_variant_ref(json_variant_by_key(v, p->bank)); + + r = json_variant_append_array(&av, bv); + if (r < 0) { + log_error_errno(r, "Failed to append JSON object: %m"); + goto finish; + } + + r = json_variant_set_field(&v, p->bank, av); + if (r < 0) { + log_error_errno(r, "Failed to add JSON field: %m"); + goto finish; + } + } + + /* Return to the original kernel measurement for the next phase calculation */ + pcr_states_restore(pcr_states, n); + } + + if (arg_json_format_flags & (JSON_FORMAT_PRETTY|JSON_FORMAT_PRETTY_AUTO)) + pager_open(arg_pager_flags); + + json_variant_dump(v, arg_json_format_flags, stdout, NULL); + r = 0; + +finish: + session_handle = tpm2_flush_context_verbose(c.esys_context, session_handle); + return r; +} + +static int compare_reported_pcr_nr(uint32_t pcr, const char *varname, const char *description) { + _cleanup_free_ char *s = NULL; + uint32_t v; + int r; + + r = efi_get_variable_string(varname, &s); + if (r == -ENOENT) + return 0; + if (r < 0) + return log_error_errno(r, "Failed to read EFI variable '%s': %m", varname); + + r = safe_atou32(s, &v); + if (r < 0) + return log_error_errno(r, "Failed to parse EFI variable '%s': %s", varname, s); + + if (pcr != v) + log_warning("PCR number reported by stub for %s (%" PRIu32 ") different from our expectation (%" PRIu32 ").\n" + "The measurements are likely inconsistent.", description, v, pcr); + + return 0; +} + +static int validate_stub(void) { + uint64_t features; + bool found = false; + int r; + + if (tpm2_support() != TPM2_SUPPORT_FULL) + return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "Sorry, system lacks full TPM2 support."); + + r = efi_stub_get_features(&features); + if (r < 0) + return log_error_errno(r, "Unable to get stub features: %m"); + + if (!FLAGS_SET(features, EFI_STUB_FEATURE_THREE_PCRS)) + log_warning("Warning: current kernel image does not support measuring itself, the command line or initrd system extension images.\n" + "The PCR measurements seen are unlikely to be valid."); + + r = compare_reported_pcr_nr(TPM_PCR_INDEX_KERNEL_IMAGE, EFI_LOADER_VARIABLE("StubPcrKernelImage"), "kernel image"); + if (r < 0) + return r; + + r = compare_reported_pcr_nr(TPM_PCR_INDEX_KERNEL_PARAMETERS, EFI_LOADER_VARIABLE("StubPcrKernelParameters"), "kernel parameters"); + if (r < 0) + return r; + + r = compare_reported_pcr_nr(TPM_PCR_INDEX_INITRD_SYSEXTS, EFI_LOADER_VARIABLE("StubPcrInitRDSysExts"), "initrd system extension images"); + if (r < 0) + return r; + + STRV_FOREACH(bank, arg_banks) { + _cleanup_free_ char *b = NULL, *p = NULL; + + b = strdup(*bank); + if (!b) + return log_oom(); + + if (asprintf(&p, "/sys/class/tpm/tpm0/pcr-%s/", ascii_strlower(b)) < 0) + return log_oom(); + + if (access(p, F_OK) < 0) { + if (errno != ENOENT) + return log_error_errno(errno, "Failed to detect if '%s' exists: %m", b); + } else + found = true; + } + + if (!found) + return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "None of the select PCR banks appear to exist."); + + return 0; +} + +static int verb_status(int argc, char *argv[], void *userdata) { + _cleanup_(json_variant_unrefp) JsonVariant *v = NULL; + + static const struct { + uint32_t nr; + const char *description; + } relevant_pcrs[] = { + { TPM_PCR_INDEX_KERNEL_IMAGE, "Unified Kernel Image" }, + { TPM_PCR_INDEX_KERNEL_PARAMETERS, "Kernel Parameters" }, + { TPM_PCR_INDEX_INITRD_SYSEXTS, "initrd System Extensions" }, + }; + + int r; + + r = validate_stub(); + if (r < 0) + return r; + + for (size_t i = 0; i < ELEMENTSOF(relevant_pcrs); i++) { + + STRV_FOREACH(bank, arg_banks) { + _cleanup_free_ char *b = NULL, *p = NULL, *s = NULL; + _cleanup_free_ void *h = NULL; + size_t l; + + b = strdup(*bank); + if (!b) + return log_oom(); + + if (asprintf(&p, "/sys/class/tpm/tpm0/pcr-%s/%" PRIu32, ascii_strlower(b), relevant_pcrs[i].nr) < 0) + return log_oom(); + + r = read_virtual_file(p, 4096, &s, NULL); + if (r == -ENOENT) + continue; + if (r < 0) + return log_error_errno(r, "Failed to read '%s': %m", p); + + r = unhexmem(strstrip(s), SIZE_MAX, &h, &l); + if (r < 0) + return log_error_errno(r, "Failed to decode PCR value '%s': %m", s); + + if (arg_json_format_flags & JSON_FORMAT_OFF) { + _cleanup_free_ char *f = NULL; + + f = hexmem(h, l); + if (!h) + return log_oom(); + + if (bank == arg_banks) { + /* before the first line for each PCR, write a short descriptive text to + * stderr, and leave the primary content on stdout */ + fflush(stdout); + fprintf(stderr, "%s# PCR[%" PRIu32 "] %s%s%s\n", + ansi_grey(), + relevant_pcrs[i].nr, + relevant_pcrs[i].description, + memeqzero(h, l) ? " (NOT SET!)" : "", + ansi_normal()); + fflush(stderr); + } + + printf("%" PRIu32 ":%s=%s\n", relevant_pcrs[i].nr, b, f); + + } else { + _cleanup_(json_variant_unrefp) JsonVariant *bv = NULL, *a = NULL; + + r = json_build(&bv, + JSON_BUILD_OBJECT( + JSON_BUILD_PAIR("pcr", JSON_BUILD_INTEGER(relevant_pcrs[i].nr)), + JSON_BUILD_PAIR("hash", JSON_BUILD_HEX(h, l)) + ) + ); + if (r < 0) + return log_error_errno(r, "Failed to build JSON object: %m"); + + a = json_variant_ref(json_variant_by_key(v, b)); + + r = json_variant_append_array(&a, bv); + if (r < 0) + return log_error_errno(r, "Failed to append PCR entry to JSON array: %m"); + + r = json_variant_set_field(&v, b, a); + if (r < 0) + return log_error_errno(r, "Failed to add bank info to object: %m"); + } + } + } + + if (!FLAGS_SET(arg_json_format_flags, JSON_FORMAT_OFF)) { + if (arg_json_format_flags & (JSON_FORMAT_PRETTY|JSON_FORMAT_PRETTY_AUTO)) + pager_open(arg_pager_flags); + + json_variant_dump(v, arg_json_format_flags, stdout, NULL); + } + + return 0; +} + +static int measure_main(int argc, char *argv[]) { + static const Verb verbs[] = { + { "help", VERB_ANY, VERB_ANY, 0, help }, + { "status", VERB_ANY, 1, VERB_DEFAULT, verb_status }, + { "calculate", VERB_ANY, 1, 0, verb_calculate }, + { "sign", VERB_ANY, 1, 0, verb_sign }, + {} + }; + + return dispatch_verb(argc, argv, verbs, NULL); +} + +static int run(int argc, char *argv[]) { + int r; + + log_show_color(true); + log_parse_environment(); + log_open(); + + r = parse_argv(argc, argv); + if (r <= 0) + return r; + + return measure_main(argc, argv); +} + +DEFINE_MAIN_FUNCTION(run); |