Lennart Poettering
df21ceca25
Now that we have recognizable errors, let's print clear error messages when we try to unlock a TPM slot. And in case of the token plugin propagate this as ENOANO so that libcryptsetup recognizes this as bad PIN. (ENOANO is documented as the error to return in that case) Fixes: #32260
358 lines
14 KiB
C
358 lines
14 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include "sd-json.h"
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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 "cryptsetup-util.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 "log.h"
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#include "random-util.h"
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#include "strv.h"
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#include "tpm2-util.h"
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#if HAVE_LIBCRYPTSETUP && HAVE_TPM2
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static int get_pin(
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usec_t until,
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const char *askpw_credential,
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AskPasswordFlags askpw_flags,
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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 (FLAGS_SET(askpw_flags, ASK_PASSWORD_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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AskPasswordRequest req = {
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.tty_fd = -EBADF,
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.message = "Please enter TPM2 PIN:",
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.icon = "drive-harddisk",
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.keyring = "tpm2-pin",
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.credential = askpw_credential,
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.until = until,
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.hup_fd = -EBADF,
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};
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pin = strv_free_erase(pin);
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r = ask_password_auto(&req, askpw_flags, &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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#endif
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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 blobs[],
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size_t n_blobs,
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const struct iovec policy_hash[],
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size_t n_policy_hash,
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const struct iovec *salt,
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const struct iovec *srk,
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const struct iovec *pcrlock_nv,
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TPM2Flags flags,
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usec_t until,
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const char *askpw_credential,
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AskPasswordFlags askpw_flags,
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struct iovec *ret_decrypted_key) {
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#if HAVE_LIBCRYPTSETUP && HAVE_TPM2
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_cleanup_(sd_json_variant_unrefp) sd_json_variant *signature_json = NULL;
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_cleanup_(iovec_done) struct iovec loaded_blob = {};
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_cleanup_free_ char *auto_device = NULL;
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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 (n_blobs == 0) {
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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.iov_base, &loaded_blob.iov_len);
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if (r < 0)
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return r;
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blobs = &loaded_blob;
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n_blobs = 1;
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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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if (r == 0) {
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/* Not found? Then search among passed credentials */
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r = tpm2_pcrlock_policy_from_credentials(srk, pcrlock_nv, &pcrlock_policy);
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if (r < 0)
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return r;
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if (r == 0)
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return log_error_errno(SYNTHETIC_ERRNO(EREMOTE), "Couldn't find pcrlock policy for volume.");
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}
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}
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_cleanup_(tpm2_context_unrefp) Tpm2Context *tpm2_context = NULL;
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r = tpm2_context_new_or_warn(device, &tpm2_context);
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if (r < 0)
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return r;
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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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blobs,
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n_blobs,
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policy_hash,
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n_policy_hash,
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srk,
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ret_decrypted_key);
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if (r == -EREMOTE)
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return log_error_errno(r, "TPM key integrity check failed. Key enrolled in superblock most likely does not belong to this TPM.");
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if (ERRNO_IS_NEG_TPM2_UNSEAL_BAD_PCR(r))
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return log_error_errno(r, "TPM policy does not match current system state. Either system has been tempered with or policy out-of-date: %m");
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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, askpw_credential, askpw_flags, &pin_str);
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if (r < 0)
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return r;
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askpw_flags &= ~ASK_PASSWORD_ACCEPT_CACHED;
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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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FLAGS_SET(flags, TPM2_FLAGS_USE_PCRLOCK) ? &pcrlock_policy : NULL,
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primary_alg,
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blobs,
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n_blobs,
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policy_hash,
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n_policy_hash,
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srk,
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ret_decrypted_key);
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if (r == -EREMOTE)
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return log_error_errno(r, "TPM key integrity check failed. Key enrolled in superblock most likely does not belong to this TPM.");
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if (ERRNO_IS_NEG_TPM2_UNSEAL_BAD_PCR(r))
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return log_error_errno(r, "TPM policy does not match current system state. Either system has been tempered with or policy out-of-date: %m");
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if (r == -ENOLCK)
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return log_error_errno(r, "TPM is in dictionary attack lock-out mode.");
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if (r == -EILSEQ) {
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log_warning_errno(r, "Bad PIN.");
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continue;
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}
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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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#else
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return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "TPM2 support not available.");
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#endif
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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_blobs,
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size_t *ret_n_blobs,
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struct iovec **ret_policy_hash,
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size_t *ret_n_policy_hash,
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struct iovec *ret_salt,
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struct iovec *ret_srk,
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struct iovec *ret_pcrlock_nv,
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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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#if HAVE_LIBCRYPTSETUP && HAVE_TPM2
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int r, token;
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assert(cd);
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assert(ret_hash_pcr_mask);
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assert(ret_pcrlock_nv);
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assert(ret_pubkey);
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assert(ret_pubkey_pcr_mask);
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assert(ret_primary_alg);
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assert(ret_blobs);
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assert(ret_n_blobs);
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assert(ret_policy_hash);
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assert(ret_n_policy_hash);
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assert(ret_salt);
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assert(ret_srk);
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assert(ret_pcrlock_nv);
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assert(ret_flags);
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assert(ret_keyslot);
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assert(ret_token);
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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 pubkey = {}, salt = {}, srk = {}, pcrlock_nv = {};
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_cleanup_(sd_json_variant_unrefp) sd_json_variant *v = NULL;
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struct iovec *blobs = NULL, *policy_hash = NULL;
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size_t n_blobs = 0, n_policy_hash = 0;
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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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CLEANUP_ARRAY(blobs, n_blobs, iovec_array_free);
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CLEANUP_ARRAY(policy_hash, n_policy_hash, iovec_array_free);
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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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&blobs,
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&n_blobs,
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&policy_hash,
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&n_policy_hash,
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&salt,
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&srk,
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&pcrlock_nv,
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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_blobs = TAKE_PTR(blobs);
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*ret_n_blobs = n_blobs;
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*ret_policy_hash = TAKE_PTR(policy_hash);
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*ret_n_policy_hash = n_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_pcrlock_nv = TAKE_STRUCT(pcrlock_nv);
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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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#else
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return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "TPM2 support not available.");
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#endif
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}
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