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/* 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 "luks2-tpm2.h"
#include "memory-util.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) {
crypt_log_debug(cd, "TPM2 device not found.");
return r;
} else if (r == -ENXIO) {
crypt_log_debug(cd, "No matching TPM2 token data found.");
return r;
}
return crypt_log_debug_errno(cd, r, TOKEN_NAME " open failed: %m.");
}
/*
* 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 funtion (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 **password, /* freed by cryptsetup_token_buffer_free */
size_t *password_len,
void *usrptr /* plugin defined parameter passed to crypt_activate_by_token*() API */) {
int r;
const char *json;
size_t blob_size, policy_hash_size, decrypted_key_size;
uint32_t pcr_mask;
systemd_tpm2_plugin_params params = {
.search_pcr_mask = UINT32_MAX
};
_cleanup_free_ void *blob = NULL, *policy_hash = NULL;
_cleanup_free_ char *base64_blob = NULL, *hex_policy_hash = NULL;
_cleanup_(erase_and_freep) void *decrypted_key = NULL;
_cleanup_(erase_and_freep) char *base64_encoded = NULL;
assert(password);
assert(password_len);
assert(token >= 0);
/* This must not fail at this moment (internal error) */
r = crypt_token_json_get(cd, token, &json);
assert(token == r);
assert(json);
if (usrptr)
params = *(systemd_tpm2_plugin_params *)usrptr;
r = parse_luks2_tpm2_data(json, params.search_pcr_mask, &pcr_mask, &base64_blob, &hex_policy_hash);
if (r < 0)
return log_debug_open_error(cd, r);
/* should not happen since cryptsetup_token_validate have passed */
r = unbase64mem(base64_blob, SIZE_MAX, &blob, &blob_size);
if (r < 0)
return log_debug_open_error(cd, r);
/* should not happen since cryptsetup_token_validate have passed */
r = unhexmem(hex_policy_hash, SIZE_MAX, &policy_hash, &policy_hash_size);
if (r < 0)
return log_debug_open_error(cd, r);
r = acquire_luks2_key(
pcr_mask,
params.device,
blob,
blob_size,
policy_hash,
policy_hash_size,
&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 */
r = base64mem(decrypted_key, decrypted_key_size, &base64_encoded);
if (r < 0)
return log_debug_open_error(cd, r);
/* free'd automaticaly by libcryptsetup */
*password_len = strlen(base64_encoded);
*password = TAKE_PTR(base64_encoded);
return 0;
}
/*
* 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 */) {
int r;
uint32_t i, pcr_mask;
size_t decoded_blob_size;
_cleanup_free_ char *base64_blob = NULL, *hex_policy_hash = NULL,
*pcrs_str = NULL, *blob_str = NULL, *policy_hash_str = NULL;
_cleanup_free_ void *decoded_blob = NULL;
assert(json);
r = parse_luks2_tpm2_data(json, UINT32_MAX, &pcr_mask, &base64_blob, &hex_policy_hash);
if (r < 0)
return (void) crypt_log_debug_errno(cd, r, "Failed to parse " TOKEN_NAME " metadata: %m.");
for (i = 0; i < TPM2_PCRS_MAX; i++) {
if ((pcr_mask & (UINT32_C(1) << i)) &&
((r = strextendf_with_separator(&pcrs_str, ", ", "%" PRIu32, i)) < 0))
return (void) crypt_log_debug_errno(cd, r, "Can not dump " TOKEN_NAME " content: %m");
}
r = unbase64mem(base64_blob, SIZE_MAX, &decoded_blob, &decoded_blob_size);
if (r < 0)
return (void) crypt_log_debug_errno(cd, r, "Can not dump " TOKEN_NAME " content: %m");
r = crypt_dump_buffer_to_hex_string(decoded_blob, decoded_blob_size, &blob_str);
if (r < 0)
return (void) crypt_log_debug_errno(cd, r, "Can not dump " TOKEN_NAME " content: %m");
r = crypt_dump_hex_string(hex_policy_hash, &policy_hash_str);
if (r < 0)
return (void) crypt_log_debug_errno(cd, r, "Can not dump " TOKEN_NAME " content: %m");
crypt_log(cd, "\ttpm2-pcrs: %s\n", pcrs_str ?: "");
crypt_log(cd, "\ttmp2-blob: %s\n", blob_str);
crypt_log(cd, "\ttmp2-policy-hash:" CRYPT_DUMP_LINE_SEP "%s\n", policy_hash_str);
}
/*
* 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) {
uintmax_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 (u >= TPM2_PCRS_MAX) {
crypt_log_debug(cd, "TPM2 PCR number out of range.");
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");
return 0;
}
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