Lennart Poettering
b2ac928088
This bool controls whether we should interactively ask for a password, which is pretty much what the ask_password-api.c APIs are about. Hence, just make the bool a flag in AskPasswordFlags enum, and use it everywhere. This still catches the flag early in upper levels of the codebase, exactly as before, but if the flag is still present in the lower layers it's also handled there and results in ENOEXEC if seen. This is mostly an excercise in simplifying our ridiculously long function call parameter lists a bit.
303 lines
12 KiB
C
303 lines
12 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(
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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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.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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};
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pin = strv_free_erase(pin);
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r = ask_password_auto(&req, until, 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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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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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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_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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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(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, askpw_credential, askpw_flags, &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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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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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 = {}, pcrlock_nv = {};
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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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&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_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_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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}
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