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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include "sd-json.h"
#include "ask-password-api.h"
#include "cryptsetup-fido2.h"
#include "env-util.h"
#include "fido2-util.h"
#include "fileio.h"
#include "hexdecoct.h"
#include "iovec-util.h"
#include "libfido2-util.h"
#include "parse-util.h"
#include "random-util.h"
#include "strv.h"
int acquire_fido2_key(
const char *volume_name,
const char *friendly_name,
const char *device,
const char *rp_id,
const void *cid,
size_t cid_size,
const char *key_file,
size_t key_file_size,
uint64_t key_file_offset,
const struct iovec *key_data,
usec_t until,
Fido2EnrollFlags required,
const char *askpw_credential,
AskPasswordFlags askpw_flags,
void **ret_decrypted_key,
size_t *ret_decrypted_key_size) {
_cleanup_(erase_and_freep) char *envpw = NULL;
_cleanup_strv_free_erase_ char **pins = NULL;
_cleanup_(iovec_done_erase) struct iovec loaded_salt = {};
bool device_exists = false;
struct iovec salt;
int r;
if ((required & (FIDO2ENROLL_PIN | FIDO2ENROLL_UP | FIDO2ENROLL_UV)) && FLAGS_SET(askpw_flags, ASK_PASSWORD_HEADLESS))
return log_error_errno(SYNTHETIC_ERRNO(ENOPKG),
"Local verification is required to unlock this volume, but the 'headless' parameter was set.");
assert(cid);
assert(key_file || iovec_is_set(key_data));
if (iovec_is_set(key_data))
salt = *key_data;
else {
if (key_file_size > 0)
log_debug("Ignoring 'keyfile-size=' option for a FIDO2 salt file.");
r = fido2_read_salt_file(
key_file, key_file_offset,
/* client= */ "cryptsetup",
/* node= */ volume_name,
&loaded_salt);
if (r < 0)
return r;
salt = loaded_salt;
}
r = getenv_steal_erase("PIN", &envpw);
if (r < 0)
return log_error_errno(r, "Failed to acquire password from environment: %m");
if (r > 0) {
pins = strv_new(envpw);
if (!pins)
return log_oom();
}
for (;;) {
if (!device_exists) {
/* Before we inquire for the PIN we'll need, if we never talked to the device, check
* if the device actually is plugged in. Otherwise we'll ask for the PIN already when
* the device is not plugged in, which is confusing. */
r = fido2_have_device(device);
if (r < 0)
return r;
if (r == 0) /* no device found, return EAGAIN so that caller will wait/watch udev */
return -EAGAIN;
device_exists = true; /* now we know for sure, a device exists, no need to ask again */
}
/* Always make an attempt before asking for PIN.
* fido2_use_hmac_hash() will perform a pre-flight check for whether the credential for
* can be found on one of the connected devices. This way, we can avoid prompting the user
* for a PIN when we are sure that no device can be used. */
r = fido2_use_hmac_hash(
device,
rp_id ?: "io.systemd.cryptsetup",
salt.iov_base, salt.iov_len,
cid, cid_size,
pins,
required,
ret_decrypted_key,
ret_decrypted_key_size);
if (!IN_SET(r,
-ENOANO, /* needs pin */
-ENOLCK)) /* pin incorrect */
return r;
device_exists = true; /* that a PIN is needed/wasn't correct means that we managed to
* talk to a device */
if (FLAGS_SET(askpw_flags, ASK_PASSWORD_HEADLESS))
return log_error_errno(SYNTHETIC_ERRNO(ENOPKG), "PIN querying disabled via 'headless' option. Use the '$PIN' environment variable.");
static const AskPasswordRequest req = {
.message = "Please enter security token PIN:",
.icon = "drive-harddisk",
.keyring = "fido2-pin",
.credential = "cryptsetup.fido2-pin",
};
pins = strv_free_erase(pins);
r = ask_password_auto(&req, until, askpw_flags, &pins);
if (r < 0)
return log_error_errno(r, "Failed to ask for user password: %m");
askpw_flags &= ~ASK_PASSWORD_ACCEPT_CACHED;
}
}
int acquire_fido2_key_auto(
struct crypt_device *cd,
const char *name,
const char *friendly_name,
const char *fido2_device,
usec_t until,
const char *askpw_credential,
AskPasswordFlags askpw_flags,
void **ret_decrypted_key,
size_t *ret_decrypted_key_size) {
_cleanup_free_ void *cid = NULL;
size_t cid_size = 0;
int r, ret = -ENOENT;
Fido2EnrollFlags required = 0;
assert(cd);
assert(name);
assert(ret_decrypted_key);
assert(ret_decrypted_key_size);
/* Loads FIDO2 metadata from LUKS2 JSON token headers. */
for (int token = 0; token < sym_crypt_token_max(CRYPT_LUKS2); token++) {
_cleanup_(sd_json_variant_unrefp) sd_json_variant *v = NULL;
sd_json_variant *w;
_cleanup_free_ void *salt = NULL;
_cleanup_free_ char *rp = NULL;
size_t salt_size = 0;
int ks;
r = cryptsetup_get_token_as_json(cd, token, "systemd-fido2", &v);
if (IN_SET(r, -ENOENT, -EINVAL, -EMEDIUMTYPE))
continue;
if (r < 0)
return log_error_errno(r, "Failed to read JSON token data off disk: %m");
ks = cryptsetup_get_keyslot_from_token(v);
if (ks < 0) {
/* Handle parsing errors of the keyslots field gracefully, since it's not 'owned' by
* us, but by the LUKS2 spec */
log_warning_errno(ks, "Failed to extract keyslot index from FIDO2 JSON data token %i, skipping: %m", token);
continue;
}
w = sd_json_variant_by_key(v, "fido2-credential");
if (!w)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"FIDO2 token data lacks 'fido2-credential' field.");
r = sd_json_variant_unbase64(w, &cid, &cid_size);
if (r < 0)
return log_error_errno(r, "Invalid base64 data in 'fido2-credential' field: %m");
w = sd_json_variant_by_key(v, "fido2-salt");
if (!w)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"FIDO2 token data lacks 'fido2-salt' field.");
assert(!salt);
assert(salt_size == 0);
r = sd_json_variant_unbase64(w, &salt, &salt_size);
if (r < 0)
return log_error_errno(r, "Failed to decode base64 encoded salt: %m");
w = sd_json_variant_by_key(v, "fido2-rp");
if (w) {
/* The "rp" field is optional. */
if (!sd_json_variant_is_string(w))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"FIDO2 token data's 'fido2-rp' field is not a string.");
assert(!rp);
rp = strdup(sd_json_variant_string(w));
if (!rp)
return log_oom();
}
w = sd_json_variant_by_key(v, "fido2-clientPin-required");
if (w) {
/* The "fido2-clientPin-required" field is optional. */
if (!sd_json_variant_is_boolean(w))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"FIDO2 token data's 'fido2-clientPin-required' field is not a boolean.");
SET_FLAG(required, FIDO2ENROLL_PIN, sd_json_variant_boolean(w));
} else
required |= FIDO2ENROLL_PIN_IF_NEEDED; /* compat with 248, where the field was unset */
w = sd_json_variant_by_key(v, "fido2-up-required");
if (w) {
/* The "fido2-up-required" field is optional. */
if (!sd_json_variant_is_boolean(w))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"FIDO2 token data's 'fido2-up-required' field is not a boolean.");
SET_FLAG(required, FIDO2ENROLL_UP, sd_json_variant_boolean(w));
} else
required |= FIDO2ENROLL_UP_IF_NEEDED; /* compat with 248 */
w = sd_json_variant_by_key(v, "fido2-uv-required");
if (w) {
/* The "fido2-uv-required" field is optional. */
if (!sd_json_variant_is_boolean(w))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"FIDO2 token data's 'fido2-uv-required' field is not a boolean.");
SET_FLAG(required, FIDO2ENROLL_UV, sd_json_variant_boolean(w));
} else
required |= FIDO2ENROLL_UV_OMIT; /* compat with 248 */
ret = acquire_fido2_key(
name,
friendly_name,
fido2_device,
rp,
cid, cid_size,
/* key_file= */ NULL, /* salt is read from LUKS header instead of key_file */
/* key_file_size= */ 0,
/* key_file_offset= */ 0,
&IOVEC_MAKE(salt, salt_size),
until,
required,
"cryptsetup.fido2-pin",
askpw_flags,
ret_decrypted_key,
ret_decrypted_key_size);
if (ret == 0)
break;
}
if (!cid)
return log_error_errno(SYNTHETIC_ERRNO(ENXIO),
"No valid FIDO2 token data found.");
if (ret == -EAGAIN) /* fido2 device does not exist, or UV is blocked; caller will prompt for retry */
return log_debug_errno(ret, "FIDO2 token does not exist, or UV is blocked.");
if (ret < 0)
return log_error_errno(ret, "Failed to unlock LUKS volume with FIDO2 token: %m");
log_info("Unlocked volume via automatically discovered security FIDO2 token.");
return ret;
}
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