homectl: add support for enrolling FIDO2 HMAC-SECRET tokens

meson.build

@@ -2184,6 +2184,7 @@ if conf.get('ENABLE_HOMED') == 1
                                 libcrypt,
                                 libopenssl,
                                 libp11kit,
+                                libfido2,
                                 libpwquality],
                 install_rpath : rootlibexecdir,
                 install : true,

src/home/homectl-fido2.c

@@ -0,0 +1,531 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#if HAVE_LIBFIDO2
+#include <fido.h>
+#endif
+
+#include "ask-password-api.h"
+#include "errno-util.h"
+#include "format-table.h"
+#include "hexdecoct.h"
+#include "homectl-fido2.h"
+#include "libcrypt-util.h"
+#include "locale-util.h"
+#include "memory-util.h"
+#include "random-util.h"
+#include "strv.h"
+
+#if HAVE_LIBFIDO2
+static int add_fido2_credential_id(
+                JsonVariant **v,
+                const void *cid,
+                size_t cid_size) {
+
+        _cleanup_(json_variant_unrefp) JsonVariant *w = NULL;
+        _cleanup_strv_free_ char **l = NULL;
+        _cleanup_free_ char *escaped = NULL;
+        int r;
+
+        assert(v);
+        assert(cid);
+
+        r = base64mem(cid, cid_size, &escaped);
+        if (r < 0)
+                return log_error_errno(r, "Failed to base64 encode FIDO2 credential ID: %m");
+
+        w = json_variant_ref(json_variant_by_key(*v, "fido2HmacCredential"));
+        if (w) {
+                r = json_variant_strv(w, &l);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to parse FIDO2 credential ID list: %m");
+
+                if (strv_contains(l, escaped))
+                        return 0;
+        }
+
+        r = strv_extend(&l, escaped);
+        if (r < 0)
+                return log_oom();
+
+        w = json_variant_unref(w);
+        r = json_variant_new_array_strv(&w, l);
+        if (r < 0)
+                return log_error_errno(r, "Failed to create FIDO2 credential ID JSON: %m");
+
+        r = json_variant_set_field(v, "fido2HmacCredential", w);
+        if (r < 0)
+                return log_error_errno(r, "Failed to update FIDO2 credential ID: %m");
+
+        return 0;
+}
+
+static int add_fido2_salt(
+                JsonVariant **v,
+                const void *cid,
+                size_t cid_size,
+                const void *fido2_salt,
+                size_t fido2_salt_size,
+                const void *secret,
+                size_t secret_size) {
+
+        _cleanup_(json_variant_unrefp) JsonVariant *l = NULL, *w = NULL, *e = NULL;
+        _cleanup_(erase_and_freep) char *base64_encoded = NULL;
+        _cleanup_free_ char *unix_salt = NULL;
+        struct crypt_data cd = {};
+        char *k;
+        int r;
+
+        r = make_salt(&unix_salt);
+        if (r < 0)
+                return log_error_errno(r, "Failed to generate salt: %m");
+
+        /* Before using UNIX hashing on the supplied key we base64 encode it, since crypt_r() and friends
+         * expect a NUL terminated string, and we use a binary key */
+        r = base64mem(secret, secret_size, &base64_encoded);
+        if (r < 0)
+                return log_error_errno(r, "Failed to base64 encode secret key: %m");
+
+        errno = 0;
+        k = crypt_r(base64_encoded, unix_salt, &cd);
+        if (!k)
+                return log_error_errno(errno_or_else(EINVAL), "Failed to UNIX hash secret key: %m");
+
+        r = json_build(&e, JSON_BUILD_OBJECT(
+                                       JSON_BUILD_PAIR("credential", JSON_BUILD_BASE64(cid, cid_size)),
+                                       JSON_BUILD_PAIR("salt", JSON_BUILD_BASE64(fido2_salt, fido2_salt_size)),
+                                       JSON_BUILD_PAIR("hashedPassword", JSON_BUILD_STRING(k))));
+        if (r < 0)
+                return log_error_errno(r, "Failed to build FIDO2 salt JSON key object: %m");
+
+        w = json_variant_ref(json_variant_by_key(*v, "privileged"));
+        l = json_variant_ref(json_variant_by_key(w, "fido2HmacSalt"));
+
+        r = json_variant_append_array(&l, e);
+        if (r < 0)
+                return log_error_errno(r, "Failed append FIDO2 salt: %m");
+
+        r = json_variant_set_field(&w, "fido2HmacSalt", l);
+        if (r < 0)
+                return log_error_errno(r, "Failed to set FDO2 salt: %m");
+
+        r = json_variant_set_field(v, "privileged", w);
+        if (r < 0)
+                return log_error_errno(r, "Failed to update privileged field: %m");
+
+        return 0;
+}
+#endif
+
+#define FIDO2_SALT_SIZE 32
+
+int identity_add_fido2_parameters(
+                JsonVariant **v,
+                const char *device) {
+
+#if HAVE_LIBFIDO2
+        _cleanup_(fido_cbor_info_free) fido_cbor_info_t *di = NULL;
+        _cleanup_(fido_assert_free) fido_assert_t *a = NULL;
+        _cleanup_(erase_and_freep) char *used_pin = NULL;
+        _cleanup_(fido_cred_free) fido_cred_t *c = NULL;
+        _cleanup_(fido_dev_free) fido_dev_t *d = NULL;
+        _cleanup_(erase_and_freep) void *salt = NULL;
+        JsonVariant *un, *realm, *rn;
+        bool found_extension = false;
+        const void *cid, *secret;
+        const char *fido_un;
+        size_t n, cid_size, secret_size;
+        char **e;
+        int r;
+
+        /* Construction is like this: we generate a salt of 32 bytes. We then ask the FIDO2 device to
+         * HMAC-SHA256 it for us with its internal key. The result is the key used by LUKS and account
+         * authentication. LUKS and UNIX password auth all do their own salting before hashing, so that FIDO2
+         * device never sees the volume key.
+         *
+         * S = HMAC-SHA256(I, D)
+         *
+         * with: S → LUKS/account authentication key                                         (never stored)
+         *       I → internal key on FIDO2 device                              (stored in the FIDO2 device)
+         *       D → salt we generate here               (stored in the privileged part of the JSON record)
+         *
+         */
+
+        assert(v);
+        assert(device);
+
+        salt = malloc(FIDO2_SALT_SIZE);
+        if (!salt)
+                return log_oom();
+
+        r = genuine_random_bytes(salt, FIDO2_SALT_SIZE, RANDOM_BLOCK);
+        if (r < 0)
+                return log_error_errno(r, "Failed to generate salt: %m");
+
+        d = fido_dev_new();
+        if (!d)
+                return log_oom();
+
+        r = fido_dev_open(d, device);
+        if (r != FIDO_OK)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to open FIDO2 device %s: %s", device, fido_strerr(r));
+
+        if (!fido_dev_is_fido2(d))
+                return log_error_errno(SYNTHETIC_ERRNO(ENODEV),
+                                       "Specified device %s is not a FIDO2 device.", device);
+
+        di = fido_cbor_info_new();
+        if (!di)
+                return log_oom();
+
+        r = fido_dev_get_cbor_info(d, di);
+        if (r != FIDO_OK)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to get CBOR device info for %s: %s", device, fido_strerr(r));
+
+        e = fido_cbor_info_extensions_ptr(di);
+        n = fido_cbor_info_extensions_len(di);
+
+        for (size_t i = 0; i < n; i++)
+                if (streq(e[i], "hmac-secret")) {
+                        found_extension = true;
+                        break;
+                }
+
+        if (!found_extension)
+                return log_error_errno(SYNTHETIC_ERRNO(ENODEV),
+                                       "Specified device %s is a FIDO2 device, but does not support the required HMAC-SECRET extension.", device);
+
+        c = fido_cred_new();
+        if (!c)
+                return log_oom();
+
+        r = fido_cred_set_extensions(c, FIDO_EXT_HMAC_SECRET);
+        if (r != FIDO_OK)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to enable HMAC-SECRET extension on FIDO2 credential: %s", fido_strerr(r));
+
+        r = fido_cred_set_rp(c, "io.systemd.home", "Home Directory");
+        if (r != FIDO_OK)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to set FIDO2 credential relying party ID/name: %s", fido_strerr(r));
+
+        r = fido_cred_set_type(c, COSE_ES256);
+        if (r != FIDO_OK)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to set FIDO2 credential type to ES256: %s", fido_strerr(r));
+
+        un = json_variant_by_key(*v, "userName");
+        if (!un)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "userName field of user record is missing");
+        if (!json_variant_is_string(un))
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "userName field of user record is not a string");
+
+        realm = json_variant_by_key(*v, "realm");
+        if (realm) {
+                if (!json_variant_is_string(realm))
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "realm field of user record is not a string");
+
+                fido_un = strjoina(json_variant_string(un), json_variant_string(realm));
+        } else
+                fido_un = json_variant_string(un);
+
+        rn = json_variant_by_key(*v, "realName");
+        if (rn && !json_variant_is_string(rn))
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "realName field of user record is not a string");
+
+        r = fido_cred_set_user(c,
+                               (const unsigned char*) fido_un, strlen(fido_un), /* We pass the user ID and name as the same */
+                               fido_un,
+                               rn ? json_variant_string(rn) : NULL,
+                               NULL /* icon URL */);
+        if (r != FIDO_OK)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to set FIDO2 credential user data: %s", fido_strerr(r));
+
+        r = fido_cred_set_clientdata_hash(c, (const unsigned char[32]) {}, 32);
+        if (r != FIDO_OK)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to set FIDO2 client data hash: %s", fido_strerr(r));
+
+        r = fido_cred_set_rk(c, FIDO_OPT_FALSE);
+        if (r != FIDO_OK)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to turn off FIDO2 resident key option of credential: %s", fido_strerr(r));
+
+        r = fido_cred_set_uv(c, FIDO_OPT_FALSE);
+        if (r != FIDO_OK)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to turn off FIDO2 user verification option of credential: %s", fido_strerr(r));
+
+        log_info("Initializing FIDO2 credential on security token.");
+
+        log_notice("%s%s(Hint: This might require verification of user presence on security token.)",
+                   emoji_enabled() ? special_glyph(SPECIAL_GLYPH_TOUCH) : "",
+                   emoji_enabled() ? " " : "");
+
+        r = fido_dev_make_cred(d, c, NULL);
+        if (r == FIDO_ERR_PIN_REQUIRED) {
+                _cleanup_free_ char *text = NULL;
+
+                if (asprintf(&text, "Please enter security token PIN:") < 0)
+                        return log_oom();
+
+                for (;;) {
+                        _cleanup_(strv_free_erasep) char **pin = NULL;
+                        char **i;
+
+                        r = ask_password_auto(text, "user-home", NULL, "fido2-pin", USEC_INFINITY, 0, &pin);
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to acquire user PIN: %m");
+
+                        r = FIDO_ERR_PIN_INVALID;
+                        STRV_FOREACH(i, pin) {
+                                if (isempty(*i)) {
+                                        log_info("PIN may not be empty.");
+                                        continue;
+                                }
+
+                                r = fido_dev_make_cred(d, c, *i);
+                                if (r == FIDO_OK) {
+                                        used_pin = strdup(*i);
+                                        if (!used_pin)
+                                                return log_oom();
+                                        break;
+                                }
+                                if (r != FIDO_ERR_PIN_INVALID)
+                                        break;
+                        }
+
+                        if (r != FIDO_ERR_PIN_INVALID)
+                                break;
+
+                        log_notice("PIN incorrect, please try again.");
+                }
+        }
+        if (r == FIDO_ERR_PIN_AUTH_BLOCKED)
+                return log_notice_errno(SYNTHETIC_ERRNO(EPERM),
+                                        "Token PIN is currently blocked, please remove and reinsert token.");
+        if (r == FIDO_ERR_ACTION_TIMEOUT)
+                return log_error_errno(SYNTHETIC_ERRNO(ENOSTR),
+                                       "Token action timeout. (User didn't interact with token quickly enough.)");
+        if (r != FIDO_OK)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to generate FIDO2 credential: %s", fido_strerr(r));
+
+        cid = fido_cred_id_ptr(c);
+        if (!cid)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to get FIDO2 credential ID.");
+
+        cid_size = fido_cred_id_len(c);
+
+        a = fido_assert_new();
+        if (!a)
+                return log_oom();
+
+        r = fido_assert_set_extensions(a, FIDO_EXT_HMAC_SECRET);
+        if (r != FIDO_OK)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to enable HMAC-SECRET extension on FIDO2 assertion: %s", fido_strerr(r));
+
+        r = fido_assert_set_hmac_salt(a, salt, FIDO2_SALT_SIZE);
+        if (r != FIDO_OK)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to set salt on FIDO2 assertion: %s", fido_strerr(r));
+
+        r = fido_assert_set_rp(a, "io.systemd.home");
+        if (r != FIDO_OK)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to set FIDO2 assertion ID: %s", fido_strerr(r));
+
+        r = fido_assert_set_clientdata_hash(a, (const unsigned char[32]) {}, 32);
+        if (r != FIDO_OK)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to set FIDO2 assertion client data hash: %s", fido_strerr(r));
+
+        r = fido_assert_allow_cred(a, cid, cid_size);
+        if (r != FIDO_OK)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to add FIDO2 assertion credential ID: %s", fido_strerr(r));
+
+        r = fido_assert_set_up(a, FIDO_OPT_FALSE);
+        if (r != FIDO_OK)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to turn off FIDO2 assertion user presence: %s", fido_strerr(r));
+
+        log_info("Generating secret key on FIDO2 security token.");
+
+        r = fido_dev_get_assert(d, a, used_pin);
+        if (r == FIDO_ERR_UP_REQUIRED) {
+                r = fido_assert_set_up(a, FIDO_OPT_TRUE);
+                if (r != FIDO_OK)
+                        return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                               "Failed to turn on FIDO2 assertion user presence: %s", fido_strerr(r));
+
+                log_notice("%s%sIn order to allow secret key generation, please verify presence on security token.",
+                           emoji_enabled() ? special_glyph(SPECIAL_GLYPH_TOUCH) : "",
+                           emoji_enabled() ? " " : "");
+
+                r = fido_dev_get_assert(d, a, used_pin);
+        }
+        if (r == FIDO_ERR_ACTION_TIMEOUT)
+                return log_error_errno(SYNTHETIC_ERRNO(ENOSTR),
+                                       "Token action timeout. (User didn't interact with token quickly enough.)");
+        if (r != FIDO_OK)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to ask token for assertion: %s", fido_strerr(r));
+
+        secret = fido_assert_hmac_secret_ptr(a, 0);
+        if (!secret)
+                return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to retrieve HMAC secret.");
+
+        secret_size = fido_assert_hmac_secret_len(a, 0);
+
+        r = add_fido2_credential_id(v, cid, cid_size);
+        if (r < 0)
+                return r;
+
+        r = add_fido2_salt(v,
+                           cid,
+                           cid_size,
+                           salt,
+                           FIDO2_SALT_SIZE,
+                           secret,
+                           secret_size);
+        if (r < 0)
+                return r;
+
+        return 0;
+#else
+        return log_error_errno(EOPNOTSUPP, "FIDO2 tokens not supported on this build.");
+#endif
+}
+
+int list_fido2_devices(void) {
+#if HAVE_LIBFIDO2
+        _cleanup_(table_unrefp) Table *t = NULL;
+        size_t allocated = 64, found = 0;
+        fido_dev_info_t *di = NULL;
+        int r;
+
+        di = fido_dev_info_new(allocated);
+        if (!di)
+                return log_oom();
+
+        r = fido_dev_info_manifest(di, allocated, &found);
+        if (r == FIDO_ERR_INTERNAL || (r == FIDO_OK && found == 0)) {
+                /* The library returns FIDO_ERR_INTERNAL when no devices are found. I wish it wouldn't. */
+                log_info("No FIDO2 devices found.");
+                r = 0;
+                goto finish;
+        }
+        if (r != FIDO_OK) {
+                r = log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to enumerate FIDO2 devices: %s", fido_strerr(r));
+                goto finish;
+        }
+
+        t = table_new("path", "manufacturer", "product");
+        if (!t) {
+                r = log_oom();
+                goto finish;
+        }
+
+        for (size_t i = 0; i < found; i++) {
+                const fido_dev_info_t *entry;
+
+                entry = fido_dev_info_ptr(di, i);
+                if (!entry) {
+                        r = log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                            "Failed to get device information for FIDO device %zu.", i);
+                        goto finish;
+                }
+
+                r = table_add_many(
+                                t,
+                                TABLE_PATH, fido_dev_info_path(entry),
+                                TABLE_STRING, fido_dev_info_manufacturer_string(entry),
+                                TABLE_STRING, fido_dev_info_product_string(entry));
+                if (r < 0) {
+                        table_log_add_error(r);
+                        goto finish;
+                }
+        }
+
+        r = table_print(t, stdout);
+        if (r < 0) {
+                log_error_errno(r, "Failed to show device table: %m");
+                goto finish;
+        }
+
+        r = 0;
+
+finish:
+        fido_dev_info_free(&di, allocated);
+        return r;
+#else
+        return log_error_errno(EOPNOTSUPP, "FIDO2 tokens not supported on this build.");
+#endif
+}
+
+int find_fido2_auto(char **ret) {
+#if HAVE_LIBFIDO2
+        _cleanup_free_ char *copy = NULL;
+        size_t di_size = 64, found = 0;
+        const fido_dev_info_t *entry;
+        fido_dev_info_t *di = NULL;
+        const char *path;
+        int r;
+
+        di = fido_dev_info_new(di_size);
+        if (!di)
+                return log_oom();
+
+        r = fido_dev_info_manifest(di, di_size, &found);
+        if (r == FIDO_ERR_INTERNAL || (r == FIDO_OK && found == 0)) {
+                /* The library returns FIDO_ERR_INTERNAL when no devices are found. I wish it wouldn't. */
+                r = log_error_errno(SYNTHETIC_ERRNO(ENODEV), "No FIDO2 devices found.");
+                goto finish;
+        }
+        if (r != FIDO_OK) {
+                r = log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to enumerate FIDO2 devices: %s", fido_strerr(r));
+                goto finish;
+        }
+        if (found > 1) {
+                r = log_error_errno(SYNTHETIC_ERRNO(ENOTUNIQ), "More than one FIDO2 device found.");
+                goto finish;
+        }
+
+        entry = fido_dev_info_ptr(di, 0);
+        if (!entry) {
+                r = log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                    "Failed to get device information for FIDO device 0.");
+                goto finish;
+        }
+
+        path = fido_dev_info_path(entry);
+        if (!path) {
+                r = log_error_errno(SYNTHETIC_ERRNO(EIO),
+                                    "Failed to query FIDO device path.");
+                goto finish;
+        }
+
+        copy = strdup(path);
+        if (!copy) {
+                r = log_oom();
+                goto finish;
+        }
+
+        *ret = TAKE_PTR(copy);
+        r = 0;
+
+finish:
+        fido_dev_info_free(&di, di_size);
+        return r;
+#else
+        return log_error_errno(EOPNOTSUPP, "FIDO2 tokens not supported on this build.");
+#endif
+}

src/home/homectl-fido2.h

@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+#pragma once
+
+#include "json.h"
+
+int identity_add_fido2_parameters(JsonVariant **v, const char *device);
+
+int list_fido2_devices(void);
+
+int find_fido2_auto(char **ret);

src/home/homectl.c

@@ -19,6 +19,7 @@
 #include "fs-util.h"
 #include "hexdecoct.h"
 #include "home-util.h"
+#include "homectl-fido2.h"
 #include "libcrypt-util.h"
 #include "locale-util.h"
 #include "main-func.h"
@@ -56,6 +57,7 @@ static char **arg_identity_filter_rlimits = NULL;
 static uint64_t arg_disk_size = UINT64_MAX;
 static uint64_t arg_disk_size_relative = UINT64_MAX;
 static char **arg_pkcs11_token_uri = NULL;
+static char **arg_fido2_device = NULL;
 static bool arg_json = false;
 static JsonFormatFlags arg_json_format_flags = 0;
 static bool arg_and_resize = false;
@@ -73,6 +75,7 @@ STATIC_DESTRUCTOR_REGISTER(arg_identity_extra_rlimits, json_variant_unrefp);
 STATIC_DESTRUCTOR_REGISTER(arg_identity_filter, strv_freep);
 STATIC_DESTRUCTOR_REGISTER(arg_identity_filter_rlimits, strv_freep);
 STATIC_DESTRUCTOR_REGISTER(arg_pkcs11_token_uri, strv_freep);
+STATIC_DESTRUCTOR_REGISTER(arg_fido2_device, strv_freep);
 
 static bool identity_properties_specified(void) {
         return
@@ -83,7 +86,8 @@ static bool identity_properties_specified(void) {
                 !json_variant_is_blank_object(arg_identity_extra_rlimits) ||
                 !strv_isempty(arg_identity_filter) ||
                 !strv_isempty(arg_identity_filter_rlimits) ||
-                !strv_isempty(arg_pkcs11_token_uri);
+                !strv_isempty(arg_pkcs11_token_uri) ||
+                !strv_isempty(arg_fido2_device);
 }
 
 static int acquire_bus(sd_bus **bus) {
@@ -1251,6 +1255,12 @@ static int acquire_new_home_record(UserRecord **ret) {
                         return r;
         }
 
+        STRV_FOREACH(i, arg_fido2_device) {
+                r = identity_add_fido2_parameters(&v, *i);
+                if (r < 0)
+                        return r;
+        }
+
         r = update_last_change(&v, true, false);
         if (r < 0)
                 return r;
@@ -1571,9 +1581,15 @@ static int acquire_updated_home_record(
                         return r;
         }
 
+        STRV_FOREACH(i, arg_fido2_device) {
+                r = identity_add_fido2_parameters(&json, *i);
+                if (r < 0)
+                        return r;
+        }
+
         /* If the user supplied a full record, then add in lastChange, but do not override. Otherwise always
          * override. */
-        r = update_last_change(&json, !!arg_pkcs11_token_uri, !arg_identity);
+        r = update_last_change(&json, arg_pkcs11_token_uri || arg_fido2_device, !arg_identity);
         if (r < 0)
                 return r;
 
@@ -1732,6 +1748,8 @@ static int passwd_home(int argc, char *argv[], void *userdata) {
 
         if (arg_pkcs11_token_uri)
                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "To change the PKCS#11 security token use 'homectl update --pkcs11-token-uri=…'.");
+        if (arg_fido2_device)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "To change the FIDO2 security token use 'homectl update --fido2-device=…'.");
         if (identity_properties_specified())
                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "The 'passwd' verb does not permit changing other record properties at the same time.");
 
@@ -2182,6 +2200,8 @@ static int help(int argc, char *argv[], void *userdata) {
                "                              Specify SSH public keys\n"
                "     --pkcs11-token-uri=URI   URI to PKCS#11 security token containing\n"
                "                              private key and matching X.509 certificate\n"
+               "     --fido2-device=PATH      Path to FIDO2 hidraw device with hmac-secret\n"
+               "                              extension\n"
                "\n%4$sAccount Management User Record Properties:%5$s\n"
                "     --locked=BOOL            Set locked account state\n"
                "     --not-before=TIMESTAMP   Do not allow logins before\n"
@@ -2328,6 +2348,7 @@ static int parse_argv(int argc, char *argv[]) {
                 ARG_EXPORT_FORMAT,
                 ARG_AUTO_LOGIN,
                 ARG_PKCS11_TOKEN_URI,
+                ARG_FIDO2_DEVICE,
                 ARG_AND_RESIZE,
                 ARG_AND_CHANGE_PASSWORD,
         };
@@ -2405,6 +2426,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "json",                        required_argument, NULL, ARG_JSON                        },
                 { "export-format",               required_argument, NULL, ARG_EXPORT_FORMAT               },
                 { "pkcs11-token-uri",            required_argument, NULL, ARG_PKCS11_TOKEN_URI            },
+                { "fido2-device",                required_argument, NULL, ARG_FIDO2_DEVICE                },
                 { "and-resize",                  required_argument, NULL, ARG_AND_RESIZE                  },
                 { "and-change-password",         required_argument, NULL, ARG_AND_CHANGE_PASSWORD         },
                 {}
@@ -3388,6 +3410,41 @@ static int parse_argv(int argc, char *argv[]) {
                         break;
                 }
 
+                case ARG_FIDO2_DEVICE: {
+                        const char *p;
+
+                        if (streq(optarg, "list"))
+                                return list_fido2_devices();
+
+                        FOREACH_STRING(p, "fido2HmacCredential", "fido2HmacSalt") {
+                                r = drop_from_identity(p);
+                                if (r < 0)
+                                        return r;
+                        }
+
+                        if (isempty(optarg)) {
+                                arg_fido2_device = strv_free(arg_fido2_device);
+                                break;
+                        }
+
+                        if (streq(optarg, "auto")) {
+                                _cleanup_free_ char *found = NULL;
+
+                                r = find_fido2_auto(&found);
+                                if (r < 0)
+                                        return r;
+
+                                r = strv_consume(&arg_fido2_device, TAKE_PTR(found));
+                        } else
+                                r = strv_extend(&arg_fido2_device, optarg);
+
+                        if (r < 0)
+                                return r;
+
+                        strv_uniq(arg_fido2_device);
+                        break;
+                }
+
                 case 'j':
                         arg_json = true;
                         arg_json_format_flags = JSON_FORMAT_PRETTY_AUTO|JSON_FORMAT_COLOR_AUTO;
@@ -3458,7 +3515,7 @@ static int parse_argv(int argc, char *argv[]) {
                 }
         }
 
-        if (!strv_isempty(arg_pkcs11_token_uri))
+        if (!strv_isempty(arg_pkcs11_token_uri) || !strv_isempty(arg_fido2_device))
                 arg_and_change_password = true;
 
         if (arg_disk_size != UINT64_MAX || arg_disk_size_relative != UINT64_MAX)

src/home/meson.build

@@ -65,6 +65,8 @@ systemd_homed_sources += [homed_gperf_c]
 homectl_sources = files('''
         home-util.c
         home-util.h
+        homectl-fido2.c
+        homectl-fido2.h
         homectl.c
         pwquality-util.c
         pwquality-util.h