Lennart Poettering
e99ca14741
The new helper combines a bunch of steps every invocation of unsetenv_erase() did so far: getenv() + strdup() + unsetenv_erase(). Let's unify this into one helper that is harder to use incorrectly. It's in inspired by TAKE_PTR() in a way: get the env var out and invalidate where it was before.
263 lines
11 KiB
C
263 lines
11 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include "ask-password-api.h"
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#include "cryptsetup-fido2.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 "libfido2-util.h"
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#include "parse-util.h"
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#include "random-util.h"
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#include "strv.h"
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int acquire_fido2_key(
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const char *volume_name,
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const char *friendly_name,
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const char *device,
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const char *rp_id,
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const void *cid,
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size_t cid_size,
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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 void *key_data,
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size_t key_data_size,
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usec_t until,
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bool headless,
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Fido2EnrollFlags required,
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void **ret_decrypted_key,
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size_t *ret_decrypted_key_size,
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AskPasswordFlags ask_password_flags) {
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_cleanup_(erase_and_freep) char *envpw = NULL;
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_cleanup_strv_free_erase_ char **pins = NULL;
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_cleanup_free_ void *loaded_salt = NULL;
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bool device_exists = false;
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const char *salt;
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size_t salt_size;
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int r;
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ask_password_flags |= ASK_PASSWORD_PUSH_CACHE | ASK_PASSWORD_ACCEPT_CACHED;
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assert(cid);
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assert(key_file || key_data);
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if (key_data) {
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salt = key_data;
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salt_size = key_data_size;
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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-fido2/%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_salt, &salt_size);
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if (r < 0)
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return r;
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salt = loaded_salt;
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}
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r = getenv_steal_erase("PIN", &envpw);
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if (r < 0)
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return log_error_errno(r, "Failed to acquire password from environment: %m");
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if (r > 0) {
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pins = strv_new(envpw);
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if (!pins)
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return log_oom();
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}
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for (;;) {
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if (!FLAGS_SET(required, FIDO2ENROLL_PIN) || pins) {
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r = fido2_use_hmac_hash(
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device,
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rp_id ?: "io.systemd.cryptsetup",
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salt, salt_size,
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cid, cid_size,
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pins,
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required,
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ret_decrypted_key,
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ret_decrypted_key_size);
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if (!IN_SET(r,
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-ENOANO, /* needs pin */
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-ENOLCK)) /* pin incorrect */
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return r;
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device_exists = true; /* that a PIN is needed/wasn't correct means that we managed to
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* talk to a device */
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}
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if (headless)
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return log_error_errno(SYNTHETIC_ERRNO(ENOPKG), "PIN querying disabled via 'headless' option. Use the '$PIN' environment variable.");
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if (!device_exists) {
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/* Before we inquire for the PIN we'll need, if we never talked to the device, check
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* if the device actually is plugged in. Otherwise we'll ask for the PIN already when
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* the device is not plugged in, which is confusing. */
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r = fido2_have_device(device);
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if (r < 0)
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return r;
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if (r == 0) /* no device found, return EAGAIN so that caller will wait/watch udev */
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return -EAGAIN;
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device_exists = true; /* now we know for sure, a device exists, no need to ask again */
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}
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pins = strv_free_erase(pins);
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r = ask_password_auto("Please enter security token PIN:", "drive-harddisk", NULL, "fido2-pin", "cryptsetup.fido2-pin", until, ask_password_flags, &pins);
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if (r < 0)
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return log_error_errno(r, "Failed to ask for user password: %m");
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ask_password_flags &= ~ASK_PASSWORD_ACCEPT_CACHED;
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}
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}
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int find_fido2_auto_data(
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struct crypt_device *cd,
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char **ret_rp_id,
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void **ret_salt,
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size_t *ret_salt_size,
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void **ret_cid,
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size_t *ret_cid_size,
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int *ret_keyslot,
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Fido2EnrollFlags *ret_required) {
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_cleanup_free_ void *cid = NULL, *salt = NULL;
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size_t cid_size = 0, salt_size = 0;
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_cleanup_free_ char *rp = NULL;
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int r, keyslot = -1;
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Fido2EnrollFlags required = 0;
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assert(cd);
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assert(ret_salt);
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assert(ret_salt_size);
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assert(ret_cid);
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assert(ret_cid_size);
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assert(ret_keyslot);
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assert(ret_required);
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/* Loads FIDO2 metadata from LUKS2 JSON token headers. */
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for (int token = 0; token < sym_crypt_token_max(CRYPT_LUKS2); token ++) {
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_cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
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JsonVariant *w;
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int ks;
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r = cryptsetup_get_token_as_json(cd, token, "systemd-fido2", &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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ks = cryptsetup_get_keyslot_from_token(v);
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if (ks < 0) {
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/* Handle parsing errors of the keyslots field gracefully, since it's not 'owned' by
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* us, but by the LUKS2 spec */
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log_warning_errno(ks, "Failed to extract keyslot index from FIDO2 JSON data token %i, skipping: %m", token);
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continue;
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}
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if (cid)
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return log_error_errno(SYNTHETIC_ERRNO(ENOTUNIQ),
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"Multiple FIDO2 tokens enrolled, cannot automatically determine token.");
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assert(keyslot < 0);
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keyslot = ks;
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w = json_variant_by_key(v, "fido2-credential");
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if (!w || !json_variant_is_string(w))
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
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"FIDO2 token data lacks 'fido2-credential' field.");
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r = unbase64mem(json_variant_string(w), SIZE_MAX, &cid, &cid_size);
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if (r < 0)
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
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"Invalid base64 data in 'fido2-credential' field.");
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w = json_variant_by_key(v, "fido2-salt");
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if (!w || !json_variant_is_string(w))
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
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"FIDO2 token data lacks 'fido2-salt' field.");
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assert(!salt);
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assert(salt_size == 0);
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r = unbase64mem(json_variant_string(w), SIZE_MAX, &salt, &salt_size);
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if (r < 0)
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return log_error_errno(r, "Failed to decode base64 encoded salt.");
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w = json_variant_by_key(v, "fido2-rp");
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if (w) {
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/* The "rp" field is optional. */
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if (!json_variant_is_string(w))
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
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"FIDO2 token data's 'fido2-rp' field is not a string.");
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assert(!rp);
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rp = strdup(json_variant_string(w));
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if (!rp)
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return log_oom();
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}
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w = json_variant_by_key(v, "fido2-clientPin-required");
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if (w) {
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/* The "fido2-clientPin-required" field is optional. */
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if (!json_variant_is_boolean(w))
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
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"FIDO2 token data's 'fido2-clientPin-required' field is not a boolean.");
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SET_FLAG(required, FIDO2ENROLL_PIN, json_variant_boolean(w));
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} else
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required |= FIDO2ENROLL_PIN_IF_NEEDED; /* compat with 248, where the field was unset */
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w = json_variant_by_key(v, "fido2-up-required");
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if (w) {
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/* The "fido2-up-required" field is optional. */
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if (!json_variant_is_boolean(w))
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
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"FIDO2 token data's 'fido2-up-required' field is not a boolean.");
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SET_FLAG(required, FIDO2ENROLL_UP, json_variant_boolean(w));
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} else
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required |= FIDO2ENROLL_UP_IF_NEEDED; /* compat with 248 */
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w = json_variant_by_key(v, "fido2-uv-required");
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if (w) {
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/* The "fido2-uv-required" field is optional. */
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if (!json_variant_is_boolean(w))
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
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"FIDO2 token data's 'fido2-uv-required' field is not a boolean.");
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SET_FLAG(required, FIDO2ENROLL_UV, json_variant_boolean(w));
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} else
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required |= FIDO2ENROLL_UV_OMIT; /* compat with 248 */
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}
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if (!cid)
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return log_error_errno(SYNTHETIC_ERRNO(ENXIO),
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"No valid FIDO2 token data found.");
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log_info("Automatically discovered security FIDO2 token unlocks volume.");
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*ret_rp_id = TAKE_PTR(rp);
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*ret_cid = TAKE_PTR(cid);
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*ret_cid_size = cid_size;
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*ret_salt = TAKE_PTR(salt);
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*ret_salt_size = salt_size;
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*ret_keyslot = keyslot;
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*ret_required = required;
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return 0;
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}
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