Lennart Poettering
8d042bc40a
Let's move more code to using struct iovec for passing around binary chunks of data. No real changes in behaviour, just refactoring.
288 lines
11 KiB
C
288 lines
11 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include "alloc-util.h"
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#include "ask-password-api.h"
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#include "cryptsetup-tpm2.h"
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#include "env-util.h"
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#include "fileio.h"
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#include "hexdecoct.h"
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#include "json.h"
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#include "parse-util.h"
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#include "random-util.h"
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#include "sha256.h"
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#include "tpm2-util.h"
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static int get_pin(usec_t until, AskPasswordFlags ask_password_flags, bool headless, char **ret_pin_str) {
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_cleanup_(erase_and_freep) char *pin_str = NULL;
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_cleanup_strv_free_erase_ char **pin = NULL;
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int r;
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assert(ret_pin_str);
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r = getenv_steal_erase("PIN", &pin_str);
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if (r < 0)
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return log_error_errno(r, "Failed to acquire PIN from environment: %m");
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if (!r) {
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if (headless)
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return log_error_errno(
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SYNTHETIC_ERRNO(ENOPKG),
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"PIN querying disabled via 'headless' option. "
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"Use the '$PIN' environment variable.");
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pin = strv_free_erase(pin);
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r = ask_password_auto(
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"Please enter TPM2 PIN:",
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"drive-harddisk",
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NULL,
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"tpm2-pin",
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"cryptsetup.tpm2-pin",
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until,
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ask_password_flags,
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&pin);
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if (r < 0)
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return log_error_errno(r, "Failed to ask for user pin: %m");
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assert(strv_length(pin) == 1);
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pin_str = strdup(pin[0]);
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if (!pin_str)
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return log_oom();
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}
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*ret_pin_str = TAKE_PTR(pin_str);
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return r;
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}
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int acquire_tpm2_key(
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const char *volume_name,
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const char *device,
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uint32_t hash_pcr_mask,
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uint16_t pcr_bank,
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const struct iovec *pubkey,
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uint32_t pubkey_pcr_mask,
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const char *signature_path,
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const char *pcrlock_path,
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uint16_t primary_alg,
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const char *key_file,
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size_t key_file_size,
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uint64_t key_file_offset,
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const struct iovec *key_data,
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const struct iovec *policy_hash,
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const struct iovec *salt,
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const struct iovec *srk,
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TPM2Flags flags,
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usec_t until,
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bool headless,
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AskPasswordFlags ask_password_flags,
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struct iovec *ret_decrypted_key) {
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_cleanup_(json_variant_unrefp) JsonVariant *signature_json = NULL;
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_cleanup_free_ void *loaded_blob = NULL;
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_cleanup_free_ char *auto_device = NULL;
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struct iovec blob;
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int r;
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assert(iovec_is_valid(salt));
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if (!device) {
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r = tpm2_find_device_auto(&auto_device);
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if (r == -ENODEV)
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return -EAGAIN; /* Tell the caller to wait for a TPM2 device to show up */
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if (r < 0)
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return log_error_errno(r, "Could not find TPM2 device: %m");
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device = auto_device;
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}
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if (iovec_is_set(key_data))
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blob = *key_data;
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else {
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_cleanup_free_ char *bindname = NULL;
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/* If we read the salt via AF_UNIX, make this client recognizable */
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if (asprintf(&bindname, "@%" PRIx64"/cryptsetup-tpm2/%s", random_u64(), volume_name) < 0)
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return log_oom();
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r = read_full_file_full(
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AT_FDCWD, key_file,
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key_file_offset == 0 ? UINT64_MAX : key_file_offset,
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key_file_size == 0 ? SIZE_MAX : key_file_size,
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READ_FULL_FILE_CONNECT_SOCKET,
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bindname,
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(char**) &loaded_blob, &blob.iov_len);
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if (r < 0)
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return r;
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blob.iov_base = loaded_blob;
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}
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if (pubkey_pcr_mask != 0) {
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r = tpm2_load_pcr_signature(signature_path, &signature_json);
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if (r < 0)
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return log_error_errno(r, "Failed to load pcr signature: %m");
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}
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_cleanup_(tpm2_pcrlock_policy_done) Tpm2PCRLockPolicy pcrlock_policy = {};
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if (FLAGS_SET(flags, TPM2_FLAGS_USE_PCRLOCK)) {
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r = tpm2_pcrlock_policy_load(pcrlock_path, &pcrlock_policy);
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if (r < 0)
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return r;
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}
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_cleanup_(tpm2_context_unrefp) Tpm2Context *tpm2_context = NULL;
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r = tpm2_context_new(device, &tpm2_context);
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if (r < 0)
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return log_error_errno(r, "Failed to create TPM2 context: %m");
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if (!(flags & TPM2_FLAGS_USE_PIN)) {
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r = tpm2_unseal(tpm2_context,
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hash_pcr_mask,
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pcr_bank,
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pubkey,
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pubkey_pcr_mask,
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signature_json,
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/* pin= */ NULL,
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FLAGS_SET(flags, TPM2_FLAGS_USE_PCRLOCK) ? &pcrlock_policy : NULL,
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primary_alg,
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&blob,
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policy_hash,
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srk,
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ret_decrypted_key);
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if (r < 0)
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return log_error_errno(r, "Failed to unseal secret using TPM2: %m");
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return r;
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}
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for (int i = 5;; i--) {
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_cleanup_(erase_and_freep) char *pin_str = NULL, *b64_salted_pin = NULL;
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if (i <= 0)
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return -EACCES;
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r = get_pin(until, ask_password_flags, headless, &pin_str);
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if (r < 0)
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return r;
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if (iovec_is_set(salt)) {
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uint8_t salted_pin[SHA256_DIGEST_SIZE] = {};
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CLEANUP_ERASE(salted_pin);
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r = tpm2_util_pbkdf2_hmac_sha256(pin_str, strlen(pin_str), salt->iov_base, salt->iov_len, salted_pin);
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if (r < 0)
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return log_error_errno(r, "Failed to perform PBKDF2: %m");
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r = base64mem(salted_pin, sizeof(salted_pin), &b64_salted_pin);
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if (r < 0)
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return log_error_errno(r, "Failed to base64 encode salted pin: %m");
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} else
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/* no salting needed, backwards compat with non-salted pins */
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b64_salted_pin = TAKE_PTR(pin_str);
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r = tpm2_unseal(tpm2_context,
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hash_pcr_mask,
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pcr_bank,
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pubkey,
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pubkey_pcr_mask,
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signature_json,
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b64_salted_pin,
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pcrlock_path ? &pcrlock_policy : NULL,
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primary_alg,
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&blob,
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policy_hash,
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srk,
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ret_decrypted_key);
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if (r < 0) {
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log_error_errno(r, "Failed to unseal secret using TPM2: %m");
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/* We get this error in case there is an authentication policy mismatch. This should
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* not happen, but this avoids confusing behavior, just in case. */
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if (!IN_SET(r, -EPERM, -ENOLCK))
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continue;
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}
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return r;
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}
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}
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int find_tpm2_auto_data(
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struct crypt_device *cd,
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uint32_t search_pcr_mask,
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int start_token,
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uint32_t *ret_hash_pcr_mask,
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uint16_t *ret_pcr_bank,
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struct iovec *ret_pubkey,
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uint32_t *ret_pubkey_pcr_mask,
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uint16_t *ret_primary_alg,
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struct iovec *ret_blob,
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struct iovec *ret_policy_hash,
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struct iovec *ret_salt,
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struct iovec *ret_srk,
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TPM2Flags *ret_flags,
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int *ret_keyslot,
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int *ret_token) {
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int r, token;
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assert(cd);
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for (token = start_token; token < sym_crypt_token_max(CRYPT_LUKS2); token++) {
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_cleanup_(iovec_done) struct iovec blob = {}, policy_hash = {}, pubkey = {}, salt = {}, srk = {};
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_cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
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uint32_t hash_pcr_mask, pubkey_pcr_mask;
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uint16_t pcr_bank, primary_alg;
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TPM2Flags flags;
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int keyslot;
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r = cryptsetup_get_token_as_json(cd, token, "systemd-tpm2", &v);
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if (IN_SET(r, -ENOENT, -EINVAL, -EMEDIUMTYPE))
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continue;
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if (r < 0)
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return log_error_errno(r, "Failed to read JSON token data off disk: %m");
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r = tpm2_parse_luks2_json(
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v,
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&keyslot,
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&hash_pcr_mask,
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&pcr_bank,
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&pubkey,
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&pubkey_pcr_mask,
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&primary_alg,
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&blob,
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&policy_hash,
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&salt,
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&srk,
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&flags);
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if (r == -EUCLEAN) /* Gracefully handle issues in JSON fields not owned by us */
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continue;
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if (r < 0)
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return log_error_errno(r, "Failed to parse TPM2 JSON data: %m");
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if (search_pcr_mask == UINT32_MAX ||
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search_pcr_mask == hash_pcr_mask) {
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if (start_token <= 0)
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log_info("Automatically discovered security TPM2 token unlocks volume.");
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*ret_hash_pcr_mask = hash_pcr_mask;
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*ret_pcr_bank = pcr_bank;
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*ret_pubkey = TAKE_STRUCT(pubkey);
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*ret_pubkey_pcr_mask = pubkey_pcr_mask;
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*ret_primary_alg = primary_alg;
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*ret_blob = TAKE_STRUCT(blob);
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*ret_policy_hash = TAKE_STRUCT(policy_hash);
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*ret_salt = TAKE_STRUCT(salt);
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*ret_keyslot = keyslot;
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*ret_token = token;
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*ret_srk = TAKE_STRUCT(srk);
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*ret_flags = flags;
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return 0;
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}
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/* PCR mask doesn't match what is configured, ignore this entry, let's see next */
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}
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return log_error_errno(SYNTHETIC_ERRNO(ENXIO), "No valid TPM2 token data found.");
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}
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