diff options
Diffstat (limited to 'src/cryptsetup/cryptsetup-tokens/cryptsetup-token-systemd-tpm2.c')
| -rw-r--r-- | src/cryptsetup/cryptsetup-tokens/cryptsetup-token-systemd-tpm2.c | 352 |
1 files changed, 352 insertions, 0 deletions
diff --git a/src/cryptsetup/cryptsetup-tokens/cryptsetup-token-systemd-tpm2.c b/src/cryptsetup/cryptsetup-tokens/cryptsetup-token-systemd-tpm2.c new file mode 100644 index 0000000..6fee831 --- /dev/null +++ b/src/cryptsetup/cryptsetup-tokens/cryptsetup-token-systemd-tpm2.c @@ -0,0 +1,352 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <errno.h> +#include <libcryptsetup.h> + +#include "cryptsetup-token.h" +#include "cryptsetup-token-util.h" +#include "hexdecoct.h" +#include "json.h" +#include "luks2-tpm2.h" +#include "memory-util.h" +#include "strv.h" +#include "tpm2-util.h" +#include "version.h" + +#define TOKEN_NAME "systemd-tpm2" +#define TOKEN_VERSION_MAJOR "1" +#define TOKEN_VERSION_MINOR "0" + +/* for libcryptsetup debug purpose */ +_public_ const char *cryptsetup_token_version(void) { + + return TOKEN_VERSION_MAJOR "." TOKEN_VERSION_MINOR " systemd-v" STRINGIFY(PROJECT_VERSION) " (" GIT_VERSION ")"; +} + +static int log_debug_open_error(struct crypt_device *cd, int r) { + if (r == -EAGAIN) + return crypt_log_debug_errno(cd, r, "TPM2 device not found."); + if (r == -ENXIO) + return crypt_log_debug_errno(cd, r, "No matching TPM2 token data found."); + + return crypt_log_debug_errno(cd, r, TOKEN_NAME " open failed: %m."); +} + +_public_ int cryptsetup_token_open_pin( + struct crypt_device *cd, /* is always LUKS2 context */ + int token /* is always >= 0 */, + const char *pin, + size_t pin_size, + char **ret_password, /* freed by cryptsetup_token_buffer_free */ + size_t *ret_password_len, + void *usrptr /* plugin defined parameter passed to crypt_activate_by_token*() API */) { + + _cleanup_(erase_and_freep) char *base64_encoded = NULL, *pin_string = NULL; + _cleanup_free_ void *blob = NULL, *pubkey = NULL, *policy_hash = NULL, *salt = NULL, *srk_buf = NULL; + size_t blob_size, policy_hash_size, decrypted_key_size, pubkey_size, salt_size = 0, srk_buf_size = 0; + _cleanup_(erase_and_freep) void *decrypted_key = NULL; + _cleanup_(json_variant_unrefp) JsonVariant *v = NULL; + uint32_t hash_pcr_mask, pubkey_pcr_mask; + systemd_tpm2_plugin_params params = { + .search_pcr_mask = UINT32_MAX + }; + uint16_t pcr_bank, primary_alg; + ssize_t base64_encoded_size; + TPM2Flags flags = 0; + const char *json; + int r; + + assert(token >= 0); + assert(!pin || pin_size > 0); + assert(ret_password); + assert(ret_password_len); + + /* This must not fail at this moment (internal error) */ + r = crypt_token_json_get(cd, token, &json); + assert(token == r); + assert(json); + + r = crypt_normalize_pin(pin, pin_size, &pin_string); + if (r < 0) + return crypt_log_debug_errno(cd, r, "Cannot normalize PIN: %m"); + + if (usrptr) + params = *(systemd_tpm2_plugin_params *)usrptr; + + r = json_parse(json, 0, &v, NULL, NULL); + if (r < 0) + return crypt_log_debug_errno(cd, r, "Failed to parse token JSON data: %m"); + + r = tpm2_parse_luks2_json( + v, + NULL, + &hash_pcr_mask, + &pcr_bank, + &pubkey, + &pubkey_size, + &pubkey_pcr_mask, + &primary_alg, + &blob, + &blob_size, + &policy_hash, + &policy_hash_size, + &salt, + &salt_size, + &srk_buf, + &srk_buf_size, + &flags); + if (r < 0) + return log_debug_open_error(cd, r); + + if (params.search_pcr_mask != UINT32_MAX && hash_pcr_mask != params.search_pcr_mask) + return crypt_log_debug_errno(cd, ENXIO, "PCR mask doesn't match expectation (%" PRIu32 " vs. %" PRIu32 ")", hash_pcr_mask, params.search_pcr_mask); + + r = acquire_luks2_key( + params.device, + hash_pcr_mask, + pcr_bank, + pubkey, pubkey_size, + pubkey_pcr_mask, + params.signature_path, + pin_string, + params.pcrlock_path, + primary_alg, + blob, + blob_size, + policy_hash, + policy_hash_size, + salt, + salt_size, + srk_buf, + srk_buf_size, + flags, + &decrypted_key, + &decrypted_key_size); + if (r < 0) + return log_debug_open_error(cd, r); + + /* Before using this key as passphrase we base64 encode it, for compat with homed */ + base64_encoded_size = base64mem(decrypted_key, decrypted_key_size, &base64_encoded); + if (base64_encoded_size < 0) + return log_debug_open_error(cd, base64_encoded_size); + + /* free'd automatically by libcryptsetup */ + *ret_password = TAKE_PTR(base64_encoded); + *ret_password_len = base64_encoded_size; + + return 0; +} + +/* + * This function is called from within following libcryptsetup calls + * provided conditions further below are met: + * + * crypt_activate_by_token(), crypt_activate_by_token_type(type == 'systemd-tpm2'): + * + * - token is assigned to at least one luks2 keyslot eligible to activate LUKS2 device + * (alternatively: name is set to null, flags contains CRYPT_ACTIVATE_ALLOW_UNBOUND_KEY + * and token is assigned to at least single keyslot). + * + * - if plugin defines validate function (see cryptsetup_token_validate below) it must have + * passed the check (aka return 0) + */ +_public_ int cryptsetup_token_open( + struct crypt_device *cd, /* is always LUKS2 context */ + int token /* is always >= 0 */, + char **ret_password, /* freed by cryptsetup_token_buffer_free */ + size_t *ret_password_len, + void *usrptr /* plugin defined parameter passed to crypt_activate_by_token*() API */) { + + return cryptsetup_token_open_pin(cd, token, NULL, 0, ret_password, ret_password_len, usrptr); +} + +/* + * libcryptsetup callback for memory deallocation of 'password' parameter passed in + * any crypt_token_open_* plugin function + */ +_public_ void cryptsetup_token_buffer_free(void *buffer, size_t buffer_len) { + erase_and_free(buffer); +} + +/* + * prints systemd-tpm2 token content in crypt_dump(). + * 'type' and 'keyslots' fields are printed by libcryptsetup + */ +_public_ void cryptsetup_token_dump( + struct crypt_device *cd /* is always LUKS2 context */, + const char *json /* validated 'systemd-tpm2' token if cryptsetup_token_validate is defined */) { + + _cleanup_free_ char *hash_pcrs_str = NULL, *pubkey_pcrs_str = NULL, *blob_str = NULL, *policy_hash_str = NULL, *pubkey_str = NULL; + _cleanup_free_ void *blob = NULL, *pubkey = NULL, *policy_hash = NULL, *salt = NULL, *srk_buf = NULL; + _cleanup_(json_variant_unrefp) JsonVariant *v = NULL; + size_t blob_size, policy_hash_size, pubkey_size, salt_size = 0, srk_buf_size = 0; + uint32_t hash_pcr_mask, pubkey_pcr_mask; + uint16_t pcr_bank, primary_alg; + TPM2Flags flags = 0; + int r; + + assert(json); + + r = json_parse(json, 0, &v, NULL, NULL); + if (r < 0) + return (void) crypt_log_debug_errno(cd, r, "Failed to parse " TOKEN_NAME " JSON object: %m"); + + r = tpm2_parse_luks2_json( + v, + NULL, + &hash_pcr_mask, + &pcr_bank, + &pubkey, + &pubkey_size, + &pubkey_pcr_mask, + &primary_alg, + &blob, + &blob_size, + &policy_hash, + &policy_hash_size, + &salt, + &salt_size, + &srk_buf, + &srk_buf_size, + &flags); + if (r < 0) + return (void) crypt_log_debug_errno(cd, r, "Failed to parse " TOKEN_NAME " JSON fields: %m"); + + hash_pcrs_str = tpm2_pcr_mask_to_string(hash_pcr_mask); + if (!hash_pcrs_str) + return (void) crypt_log_debug_errno(cd, ENOMEM, "Cannot format PCR hash mask: %m"); + + pubkey_pcrs_str = tpm2_pcr_mask_to_string(pubkey_pcr_mask); + if (!pubkey_pcrs_str) + return (void) crypt_log_debug_errno(cd, ENOMEM, "Cannot format PCR hash mask: %m"); + + r = crypt_dump_buffer_to_hex_string(blob, blob_size, &blob_str); + if (r < 0) + return (void) crypt_log_debug_errno(cd, r, "Cannot dump " TOKEN_NAME " content: %m"); + + r = crypt_dump_buffer_to_hex_string(pubkey, pubkey_size, &pubkey_str); + if (r < 0) + return (void) crypt_log_debug_errno(cd, r, "Cannot dump " TOKEN_NAME " content: %m"); + + r = crypt_dump_buffer_to_hex_string(policy_hash, policy_hash_size, &policy_hash_str); + if (r < 0) + return (void) crypt_log_debug_errno(cd, r, "Cannot dump " TOKEN_NAME " content: %m"); + + crypt_log(cd, "\ttpm2-hash-pcrs: %s\n", strna(hash_pcrs_str)); + crypt_log(cd, "\ttpm2-pcr-bank: %s\n", strna(tpm2_hash_alg_to_string(pcr_bank))); + crypt_log(cd, "\ttpm2-pubkey:" CRYPT_DUMP_LINE_SEP "%s\n", pubkey_str); + crypt_log(cd, "\ttpm2-pubkey-pcrs: %s\n", strna(pubkey_pcrs_str)); + crypt_log(cd, "\ttpm2-primary-alg: %s\n", strna(tpm2_asym_alg_to_string(primary_alg))); + crypt_log(cd, "\ttpm2-blob: %s\n", blob_str); + crypt_log(cd, "\ttpm2-policy-hash:" CRYPT_DUMP_LINE_SEP "%s\n", policy_hash_str); + crypt_log(cd, "\ttpm2-pin: %s\n", true_false(flags & TPM2_FLAGS_USE_PIN)); + crypt_log(cd, "\ttpm2-pcrlock: %s\n", true_false(flags & TPM2_FLAGS_USE_PCRLOCK)); + crypt_log(cd, "\ttpm2-salt: %s\n", true_false(salt)); + crypt_log(cd, "\ttpm2-srk: %s\n", true_false(srk_buf)); +} + +/* + * Note: + * If plugin is available in library path, it's called in before following libcryptsetup calls: + * + * crypt_token_json_set, crypt_dump, any crypt_activate_by_token_* flavour + */ +_public_ int cryptsetup_token_validate( + struct crypt_device *cd, /* is always LUKS2 context */ + const char *json /* contains valid 'type' and 'keyslots' fields. 'type' is 'systemd-tpm2' */) { + + int r; + JsonVariant *w, *e; + _cleanup_(json_variant_unrefp) JsonVariant *v = NULL; + + assert(json); + + r = json_parse(json, 0, &v, NULL, NULL); + if (r < 0) + return crypt_log_debug_errno(cd, r, "Could not parse " TOKEN_NAME " json object: %m"); + + w = json_variant_by_key(v, "tpm2-pcrs"); + if (!w || !json_variant_is_array(w)) { + crypt_log_debug(cd, "TPM2 token data lacks 'tpm2-pcrs' field."); + return 1; + } + + JSON_VARIANT_ARRAY_FOREACH(e, w) { + uint64_t u; + + if (!json_variant_is_number(e)) { + crypt_log_debug(cd, "TPM2 PCR is not a number."); + return 1; + } + + u = json_variant_unsigned(e); + if (!TPM2_PCR_INDEX_VALID(u)) { + crypt_log_debug(cd, "TPM2 PCR number out of range."); + return 1; + } + } + + /* The bank field is optional, since it was added in systemd 250 only. Before the bank was hardcoded + * to SHA256. */ + w = json_variant_by_key(v, "tpm2-pcr-bank"); + if (w) { + /* The PCR bank field is optional */ + + if (!json_variant_is_string(w)) { + crypt_log_debug(cd, "TPM2 PCR bank is not a string."); + return 1; + } + + if (tpm2_hash_alg_from_string(json_variant_string(w)) < 0) { + crypt_log_debug(cd, "TPM2 PCR bank invalid or not supported: %s.", json_variant_string(w)); + return 1; + } + } + + /* The primary key algorithm field is optional, since it was also added in systemd 250 only. Before + * the algorithm was hardcoded to ECC. */ + w = json_variant_by_key(v, "tpm2-primary-alg"); + if (w) { + /* The primary key algorithm is optional */ + + if (!json_variant_is_string(w)) { + crypt_log_debug(cd, "TPM2 primary key algorithm is not a string."); + return 1; + } + + if (tpm2_asym_alg_from_string(json_variant_string(w)) < 0) { + crypt_log_debug(cd, "TPM2 primary key algorithm invalid or not supported: %s", json_variant_string(w)); + return 1; + } + } + + w = json_variant_by_key(v, "tpm2-blob"); + if (!w || !json_variant_is_string(w)) { + crypt_log_debug(cd, "TPM2 token data lacks 'tpm2-blob' field."); + return 1; + } + + r = unbase64mem(json_variant_string(w), SIZE_MAX, NULL, NULL); + if (r < 0) + return crypt_log_debug_errno(cd, r, "Invalid base64 data in 'tpm2-blob' field: %m"); + + w = json_variant_by_key(v, "tpm2-policy-hash"); + if (!w || !json_variant_is_string(w)) { + crypt_log_debug(cd, "TPM2 token data lacks 'tpm2-policy-hash' field."); + return 1; + } + + r = unhexmem(json_variant_string(w), SIZE_MAX, NULL, NULL); + if (r < 0) + return crypt_log_debug_errno(cd, r, "Invalid base64 data in 'tpm2-policy-hash' field: %m"); + + w = json_variant_by_key(v, "tpm2-pin"); + if (w) { + if (!json_variant_is_boolean(w)) { + crypt_log_debug(cd, "TPM2 PIN policy is not a boolean."); + return 1; + } + } + + return 0; +} |