/* $NetBSD: sk-usbhid.c,v 1.8.2.1 2023/11/02 22:15:22 sborrill Exp $ */ /* $OpenBSD: sk-usbhid.c,v 1.46 2023/03/28 06:12:38 dtucker Exp $ */ /* * Copyright (c) 2019 Markus Friedl * Copyright (c) 2020 Pedro Martelletto * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include "includes.h" __RCSID("$NetBSD: sk-usbhid.c,v 1.8.2.1 2023/11/02 22:15:22 sborrill Exp $"); #include #include #include #include #include #include #include #ifdef WITH_OPENSSL #include #include #include #include #include #include #endif /* WITH_OPENSSL */ #include #include #ifndef SK_STANDALONE # include "log.h" # include "xmalloc.h" # include "misc.h" /* * If building as part of OpenSSH, then rename exported functions. * This must be done before including sk-api.h. */ # define sk_api_version ssh_sk_api_version # define sk_enroll ssh_sk_enroll # define sk_sign ssh_sk_sign # define sk_load_resident_keys ssh_sk_load_resident_keys #endif /* !SK_STANDALONE */ #include "sk-api.h" /* #define SK_DEBUG 1 */ #ifdef SK_DEBUG #define SSH_FIDO_INIT_ARG FIDO_DEBUG #else #define SSH_FIDO_INIT_ARG 0 #endif #define MAX_FIDO_DEVICES 8 #define FIDO_POLL_MS 50 #define SELECT_MS 15000 #define POLL_SLEEP_NS 200000000 #ifndef FIDO_ERR_OPERATION_DENIED #define FIDO_ERR_OPERATION_DENIED 0x27 #endif struct sk_usbhid { fido_dev_t *dev; char *path; }; /* Return the version of the middleware API */ uint32_t sk_api_version(void); /* Enroll a U2F key (private key generation) */ int sk_enroll(uint32_t alg, const uint8_t *challenge, size_t challenge_len, const char *application, uint8_t flags, const char *pin, struct sk_option **options, struct sk_enroll_response **enroll_response); /* Sign a challenge */ int sk_sign(uint32_t alg, const uint8_t *data, size_t data_len, const char *application, const uint8_t *key_handle, size_t key_handle_len, uint8_t flags, const char *pin, struct sk_option **options, struct sk_sign_response **sign_response); /* Load resident keys */ int sk_load_resident_keys(const char *pin, struct sk_option **options, struct sk_resident_key ***rks, size_t *nrks); static void skdebug(const char *func, const char *fmt, ...) __attribute__((__format__ (printf, 2, 3))); static void skdebug(const char *func, const char *fmt, ...) { #if !defined(SK_STANDALONE) char *msg; va_list ap; va_start(ap, fmt); xvasprintf(&msg, fmt, ap); va_end(ap); debug("%s: %s", func, msg); free(msg); #elif defined(SK_DEBUG) va_list ap; va_start(ap, fmt); fprintf(stderr, "%s: ", func); vfprintf(stderr, fmt, ap); fputc('\n', stderr); va_end(ap); #else (void)func; /* XXX */ (void)fmt; /* XXX */ #endif } uint32_t sk_api_version(void) { return SSH_SK_VERSION_MAJOR; } static struct sk_usbhid * sk_open(const char *path) { struct sk_usbhid *sk; int r; if (path == NULL) { skdebug(__func__, "path == NULL"); return NULL; } if ((sk = calloc(1, sizeof(*sk))) == NULL) { skdebug(__func__, "calloc sk failed"); return NULL; } if ((sk->path = strdup(path)) == NULL) { skdebug(__func__, "strdup path failed"); free(sk); return NULL; } if ((sk->dev = fido_dev_new()) == NULL) { skdebug(__func__, "fido_dev_new failed"); free(sk->path); free(sk); return NULL; } if ((r = fido_dev_open(sk->dev, sk->path)) != FIDO_OK) { skdebug(__func__, "fido_dev_open %s failed: %s", sk->path, fido_strerr(r)); fido_dev_free(&sk->dev); free(sk->path); free(sk); return NULL; } return sk; } static void sk_close(struct sk_usbhid *sk) { if (sk == NULL) return; fido_dev_cancel(sk->dev); /* cancel any pending operation */ fido_dev_close(sk->dev); fido_dev_free(&sk->dev); free(sk->path); free(sk); } static struct sk_usbhid ** sk_openv(const fido_dev_info_t *devlist, size_t ndevs, size_t *nopen) { const fido_dev_info_t *di; struct sk_usbhid **skv; size_t i; *nopen = 0; if ((skv = calloc(ndevs, sizeof(*skv))) == NULL) { skdebug(__func__, "calloc skv failed"); return NULL; } for (i = 0; i < ndevs; i++) { if ((di = fido_dev_info_ptr(devlist, i)) == NULL) skdebug(__func__, "fido_dev_info_ptr failed"); else if ((skv[*nopen] = sk_open(fido_dev_info_path(di))) == NULL) skdebug(__func__, "sk_open failed"); else (*nopen)++; } if (*nopen == 0) { for (i = 0; i < ndevs; i++) sk_close(skv[i]); free(skv); skv = NULL; } return skv; } static void sk_closev(struct sk_usbhid **skv, size_t nsk) { size_t i; for (i = 0; i < nsk; i++) sk_close(skv[i]); free(skv); } static int sk_touch_begin(struct sk_usbhid **skv, size_t nsk) { size_t i, ok = 0; int r; for (i = 0; i < nsk; i++) if ((r = fido_dev_get_touch_begin(skv[i]->dev)) != FIDO_OK) skdebug(__func__, "fido_dev_get_touch_begin %s failed:" " %s", skv[i]->path, fido_strerr(r)); else ok++; return ok ? 0 : -1; } static int sk_touch_poll(struct sk_usbhid **skv, size_t nsk, int *touch, size_t *idx) { struct timespec ts_pause; size_t npoll, i; int r; ts_pause.tv_sec = 0; ts_pause.tv_nsec = POLL_SLEEP_NS; nanosleep(&ts_pause, NULL); npoll = nsk; for (i = 0; i < nsk; i++) { if (skv[i] == NULL) continue; /* device discarded */ skdebug(__func__, "polling %s", skv[i]->path); if ((r = fido_dev_get_touch_status(skv[i]->dev, touch, FIDO_POLL_MS)) != FIDO_OK) { skdebug(__func__, "fido_dev_get_touch_status %s: %s", skv[i]->path, fido_strerr(r)); sk_close(skv[i]); /* discard device */ skv[i] = NULL; if (--npoll == 0) { skdebug(__func__, "no device left to poll"); return -1; } } else if (*touch) { *idx = i; return 0; } } *touch = 0; return 0; } /* Check if the specified key handle exists on a given sk. */ static int sk_try(const struct sk_usbhid *sk, const char *application, const uint8_t *key_handle, size_t key_handle_len) { fido_assert_t *assert = NULL; int r = FIDO_ERR_INTERNAL; uint8_t message[32]; memset(message, '\0', sizeof(message)); if ((assert = fido_assert_new()) == NULL) { skdebug(__func__, "fido_assert_new failed"); goto out; } /* generate an invalid signature on FIDO2 tokens */ if ((r = fido_assert_set_clientdata(assert, message, sizeof(message))) != FIDO_OK) { skdebug(__func__, "fido_assert_set_clientdata: %s", fido_strerr(r)); goto out; } if ((r = fido_assert_set_rp(assert, application)) != FIDO_OK) { skdebug(__func__, "fido_assert_set_rp: %s", fido_strerr(r)); goto out; } if ((r = fido_assert_allow_cred(assert, key_handle, key_handle_len)) != FIDO_OK) { skdebug(__func__, "fido_assert_allow_cred: %s", fido_strerr(r)); goto out; } if ((r = fido_assert_set_up(assert, FIDO_OPT_FALSE)) != FIDO_OK) { skdebug(__func__, "fido_assert_up: %s", fido_strerr(r)); goto out; } r = fido_dev_get_assert(sk->dev, assert, NULL); skdebug(__func__, "fido_dev_get_assert: %s", fido_strerr(r)); if (r == FIDO_ERR_USER_PRESENCE_REQUIRED) { /* U2F tokens may return this */ r = FIDO_OK; } out: fido_assert_free(&assert); return r != FIDO_OK ? -1 : 0; } static int check_sk_options(fido_dev_t *dev, const char *opt, int *ret) { fido_cbor_info_t *info; char * const *name; const bool *value; size_t len, i; int r; *ret = -1; if (!fido_dev_is_fido2(dev)) { skdebug(__func__, "device is not fido2"); return 0; } if ((info = fido_cbor_info_new()) == NULL) { skdebug(__func__, "fido_cbor_info_new failed"); return -1; } if ((r = fido_dev_get_cbor_info(dev, info)) != FIDO_OK) { skdebug(__func__, "fido_dev_get_cbor_info: %s", fido_strerr(r)); fido_cbor_info_free(&info); return -1; } name = fido_cbor_info_options_name_ptr(info); value = fido_cbor_info_options_value_ptr(info); len = fido_cbor_info_options_len(info); for (i = 0; i < len; i++) { if (!strcmp(name[i], opt)) { *ret = value[i]; break; } } fido_cbor_info_free(&info); if (*ret == -1) skdebug(__func__, "option %s is unknown", opt); else skdebug(__func__, "option %s is %s", opt, *ret ? "on" : "off"); return 0; } static struct sk_usbhid * sk_select_by_cred(const fido_dev_info_t *devlist, size_t ndevs, const char *application, const uint8_t *key_handle, size_t key_handle_len) { struct sk_usbhid **skv, *sk; size_t skvcnt, i; int internal_uv; if ((skv = sk_openv(devlist, ndevs, &skvcnt)) == NULL) { skdebug(__func__, "sk_openv failed"); return NULL; } if (skvcnt == 1 && check_sk_options(skv[0]->dev, "uv", &internal_uv) == 0 && internal_uv != -1) { sk = skv[0]; skv[0] = NULL; goto out; } sk = NULL; for (i = 0; i < skvcnt; i++) { if (sk_try(skv[i], application, key_handle, key_handle_len) == 0) { sk = skv[i]; skv[i] = NULL; skdebug(__func__, "found key in %s", sk->path); break; } } out: sk_closev(skv, skvcnt); return sk; } static struct sk_usbhid * sk_select_by_touch(const fido_dev_info_t *devlist, size_t ndevs) { struct sk_usbhid **skv, *sk; struct timeval tv_start, tv_now, tv_delta; size_t skvcnt, idx; int touch, ms_remain; if ((skv = sk_openv(devlist, ndevs, &skvcnt)) == NULL) { skdebug(__func__, "sk_openv failed"); return NULL; } sk = NULL; if (skvcnt < 2) { if (skvcnt == 1) { /* single candidate */ sk = skv[0]; skv[0] = NULL; } goto out; } if (sk_touch_begin(skv, skvcnt) == -1) { skdebug(__func__, "sk_touch_begin failed"); goto out; } monotime_tv(&tv_start); do { if (sk_touch_poll(skv, skvcnt, &touch, &idx) == -1) { skdebug(__func__, "sk_touch_poll failed"); goto out; } if (touch) { sk = skv[idx]; skv[idx] = NULL; goto out; } monotime_tv(&tv_now); timersub(&tv_now, &tv_start, &tv_delta); ms_remain = SELECT_MS - tv_delta.tv_sec * 1000 - tv_delta.tv_usec / 1000; } while (ms_remain >= FIDO_POLL_MS); skdebug(__func__, "timeout"); out: sk_closev(skv, skvcnt); return sk; } static struct sk_usbhid * sk_probe(const char *application, const uint8_t *key_handle, size_t key_handle_len, int probe_resident) { struct sk_usbhid *sk; fido_dev_info_t *devlist; size_t ndevs; int r; if ((devlist = fido_dev_info_new(MAX_FIDO_DEVICES)) == NULL) { skdebug(__func__, "fido_dev_info_new failed"); return NULL; } if ((r = fido_dev_info_manifest(devlist, MAX_FIDO_DEVICES, &ndevs)) != FIDO_OK) { skdebug(__func__, "fido_dev_info_manifest failed: %s", fido_strerr(r)); fido_dev_info_free(&devlist, MAX_FIDO_DEVICES); return NULL; } skdebug(__func__, "%zu device(s) detected", ndevs); if (ndevs == 0) { sk = NULL; } else if (application != NULL && key_handle != NULL) { skdebug(__func__, "selecting sk by cred"); sk = sk_select_by_cred(devlist, ndevs, application, key_handle, key_handle_len); } else { skdebug(__func__, "selecting sk by touch"); sk = sk_select_by_touch(devlist, ndevs); } fido_dev_info_free(&devlist, MAX_FIDO_DEVICES); return sk; } #ifdef WITH_OPENSSL /* * The key returned via fido_cred_pubkey_ptr() is in affine coordinates, * but the API expects a SEC1 octet string. */ static int pack_public_key_ecdsa(const fido_cred_t *cred, struct sk_enroll_response *response) { const uint8_t *ptr; BIGNUM *x = NULL, *y = NULL; EC_POINT *q = NULL; EC_GROUP *g = NULL; int ret = -1; response->public_key = NULL; response->public_key_len = 0; if ((x = BN_new()) == NULL || (y = BN_new()) == NULL || (g = EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1)) == NULL || (q = EC_POINT_new(g)) == NULL) { skdebug(__func__, "libcrypto setup failed"); goto out; } if ((ptr = fido_cred_pubkey_ptr(cred)) == NULL) { skdebug(__func__, "fido_cred_pubkey_ptr failed"); goto out; } if (fido_cred_pubkey_len(cred) != 64) { skdebug(__func__, "bad fido_cred_pubkey_len %zu", fido_cred_pubkey_len(cred)); goto out; } if (BN_bin2bn(ptr, 32, x) == NULL || BN_bin2bn(ptr + 32, 32, y) == NULL) { skdebug(__func__, "BN_bin2bn failed"); goto out; } if (EC_POINT_set_affine_coordinates_GFp(g, q, x, y, NULL) != 1) { skdebug(__func__, "EC_POINT_set_affine_coordinates_GFp failed"); goto out; } response->public_key_len = EC_POINT_point2oct(g, q, POINT_CONVERSION_UNCOMPRESSED, NULL, 0, NULL); if (response->public_key_len == 0 || response->public_key_len > 2048) { skdebug(__func__, "bad pubkey length %zu", response->public_key_len); goto out; } if ((response->public_key = malloc(response->public_key_len)) == NULL) { skdebug(__func__, "malloc pubkey failed"); goto out; } if (EC_POINT_point2oct(g, q, POINT_CONVERSION_UNCOMPRESSED, response->public_key, response->public_key_len, NULL) == 0) { skdebug(__func__, "EC_POINT_point2oct failed"); goto out; } /* success */ ret = 0; out: if (ret != 0 && response->public_key != NULL) { memset(response->public_key, 0, response->public_key_len); free(response->public_key); response->public_key = NULL; } EC_POINT_free(q); EC_GROUP_free(g); BN_clear_free(x); BN_clear_free(y); return ret; } #endif /* WITH_OPENSSL */ static int pack_public_key_ed25519(const fido_cred_t *cred, struct sk_enroll_response *response) { const uint8_t *ptr; size_t len; int ret = -1; response->public_key = NULL; response->public_key_len = 0; if ((len = fido_cred_pubkey_len(cred)) != 32) { skdebug(__func__, "bad fido_cred_pubkey_len len %zu", len); goto out; } if ((ptr = fido_cred_pubkey_ptr(cred)) == NULL) { skdebug(__func__, "fido_cred_pubkey_ptr failed"); goto out; } response->public_key_len = len; if ((response->public_key = malloc(response->public_key_len)) == NULL) { skdebug(__func__, "malloc pubkey failed"); goto out; } memcpy(response->public_key, ptr, len); ret = 0; out: if (ret != 0) free(response->public_key); return ret; } static int pack_public_key(uint32_t alg, const fido_cred_t *cred, struct sk_enroll_response *response) { switch(alg) { #ifdef WITH_OPENSSL case SSH_SK_ECDSA: return pack_public_key_ecdsa(cred, response); #endif /* WITH_OPENSSL */ case SSH_SK_ED25519: return pack_public_key_ed25519(cred, response); default: return -1; } } static int fidoerr_to_skerr(int fidoerr) { switch (fidoerr) { case FIDO_ERR_UNSUPPORTED_OPTION: case FIDO_ERR_UNSUPPORTED_ALGORITHM: return SSH_SK_ERR_UNSUPPORTED; case FIDO_ERR_PIN_REQUIRED: case FIDO_ERR_PIN_INVALID: case FIDO_ERR_OPERATION_DENIED: return SSH_SK_ERR_PIN_REQUIRED; default: return -1; } } static int check_enroll_options(struct sk_option **options, char **devicep, uint8_t *user_id, size_t user_id_len) { size_t i; if (options == NULL) return 0; for (i = 0; options[i] != NULL; i++) { if (strcmp(options[i]->name, "device") == 0) { if ((*devicep = strdup(options[i]->value)) == NULL) { skdebug(__func__, "strdup device failed"); return -1; } skdebug(__func__, "requested device %s", *devicep); } else if (strcmp(options[i]->name, "user") == 0) { if (strlcpy((char *)user_id, options[i]->value, user_id_len) >= user_id_len) { skdebug(__func__, "user too long"); return -1; } skdebug(__func__, "requested user %s", (char *)user_id); } else { skdebug(__func__, "requested unsupported option %s", options[i]->name); if (options[i]->required) { skdebug(__func__, "unknown required option"); return -1; } } } return 0; } static int key_lookup(fido_dev_t *dev, const char *application, const uint8_t *user_id, size_t user_id_len, const char *pin) { fido_assert_t *assert = NULL; uint8_t message[32]; int r = FIDO_ERR_INTERNAL; int sk_supports_uv, uv; size_t i; memset(message, '\0', sizeof(message)); if ((assert = fido_assert_new()) == NULL) { skdebug(__func__, "fido_assert_new failed"); goto out; } /* generate an invalid signature on FIDO2 tokens */ if ((r = fido_assert_set_clientdata(assert, message, sizeof(message))) != FIDO_OK) { skdebug(__func__, "fido_assert_set_clientdata: %s", fido_strerr(r)); goto out; } if ((r = fido_assert_set_rp(assert, application)) != FIDO_OK) { skdebug(__func__, "fido_assert_set_rp: %s", fido_strerr(r)); goto out; } if ((r = fido_assert_set_up(assert, FIDO_OPT_FALSE)) != FIDO_OK) { skdebug(__func__, "fido_assert_set_up: %s", fido_strerr(r)); goto out; } uv = FIDO_OPT_OMIT; if (pin == NULL && check_sk_options(dev, "uv", &sk_supports_uv) == 0 && sk_supports_uv != -1) uv = FIDO_OPT_TRUE; if ((r = fido_assert_set_uv(assert, uv)) != FIDO_OK) { skdebug(__func__, "fido_assert_set_uv: %s", fido_strerr(r)); goto out; } if ((r = fido_dev_get_assert(dev, assert, pin)) != FIDO_OK) { skdebug(__func__, "fido_dev_get_assert: %s", fido_strerr(r)); goto out; } r = FIDO_ERR_NO_CREDENTIALS; skdebug(__func__, "%zu signatures returned", fido_assert_count(assert)); for (i = 0; i < fido_assert_count(assert); i++) { if (fido_assert_user_id_len(assert, i) == user_id_len && memcmp(fido_assert_user_id_ptr(assert, i), user_id, user_id_len) == 0) { skdebug(__func__, "credential exists"); r = FIDO_OK; goto out; } } out: fido_assert_free(&assert); return r; } int sk_enroll(uint32_t alg, const uint8_t *challenge, size_t challenge_len, const char *application, uint8_t flags, const char *pin, struct sk_option **options, struct sk_enroll_response **enroll_response) { fido_cred_t *cred = NULL; const uint8_t *ptr; uint8_t user_id[32]; struct sk_usbhid *sk = NULL; struct sk_enroll_response *response = NULL; size_t len; int credprot; int cose_alg; int ret = SSH_SK_ERR_GENERAL; int r; char *device = NULL; fido_init(SSH_FIDO_INIT_ARG); if (enroll_response == NULL) { skdebug(__func__, "enroll_response == NULL"); goto out; } *enroll_response = NULL; memset(user_id, 0, sizeof(user_id)); if (check_enroll_options(options, &device, user_id, sizeof(user_id)) != 0) goto out; /* error already logged */ switch(alg) { #ifdef WITH_OPENSSL case SSH_SK_ECDSA: cose_alg = COSE_ES256; break; #endif /* WITH_OPENSSL */ case SSH_SK_ED25519: cose_alg = COSE_EDDSA; break; default: skdebug(__func__, "unsupported key type %d", alg); goto out; } if (device != NULL) sk = sk_open(device); else sk = sk_probe(NULL, NULL, 0, 0); if (sk == NULL) { ret = SSH_SK_ERR_DEVICE_NOT_FOUND; skdebug(__func__, "failed to find sk"); goto out; } skdebug(__func__, "using device %s", sk->path); if ((flags & SSH_SK_RESIDENT_KEY) != 0 && (flags & SSH_SK_FORCE_OPERATION) == 0 && (r = key_lookup(sk->dev, application, user_id, sizeof(user_id), pin)) != FIDO_ERR_NO_CREDENTIALS) { if (r != FIDO_OK) { ret = fidoerr_to_skerr(r); skdebug(__func__, "key_lookup failed"); } else { ret = SSH_SK_ERR_CREDENTIAL_EXISTS; skdebug(__func__, "key exists"); } goto out; } if ((cred = fido_cred_new()) == NULL) { skdebug(__func__, "fido_cred_new failed"); goto out; } if ((r = fido_cred_set_type(cred, cose_alg)) != FIDO_OK) { skdebug(__func__, "fido_cred_set_type: %s", fido_strerr(r)); goto out; } if ((r = fido_cred_set_clientdata(cred, challenge, challenge_len)) != FIDO_OK) { skdebug(__func__, "fido_cred_set_clientdata: %s", fido_strerr(r)); goto out; } if ((r = fido_cred_set_rk(cred, (flags & SSH_SK_RESIDENT_KEY) != 0 ? FIDO_OPT_TRUE : FIDO_OPT_OMIT)) != FIDO_OK) { skdebug(__func__, "fido_cred_set_rk: %s", fido_strerr(r)); goto out; } if ((r = fido_cred_set_user(cred, user_id, sizeof(user_id), "openssh", "openssh", NULL)) != FIDO_OK) { skdebug(__func__, "fido_cred_set_user: %s", fido_strerr(r)); goto out; } if ((r = fido_cred_set_rp(cred, application, NULL)) != FIDO_OK) { skdebug(__func__, "fido_cred_set_rp: %s", fido_strerr(r)); goto out; } if ((flags & (SSH_SK_RESIDENT_KEY|SSH_SK_USER_VERIFICATION_REQD)) != 0) { if (!fido_dev_supports_cred_prot(sk->dev)) { skdebug(__func__, "%s does not support credprot, " "refusing to create unprotected " "resident/verify-required key", sk->path); ret = SSH_SK_ERR_UNSUPPORTED; goto out; } if ((flags & SSH_SK_USER_VERIFICATION_REQD)) credprot = FIDO_CRED_PROT_UV_REQUIRED; else credprot = FIDO_CRED_PROT_UV_OPTIONAL_WITH_ID; if ((r = fido_cred_set_prot(cred, credprot)) != FIDO_OK) { skdebug(__func__, "fido_cred_set_prot: %s", fido_strerr(r)); ret = fidoerr_to_skerr(r); goto out; } } if ((r = fido_dev_make_cred(sk->dev, cred, pin)) != FIDO_OK) { skdebug(__func__, "fido_dev_make_cred: %s", fido_strerr(r)); ret = fidoerr_to_skerr(r); goto out; } if (fido_cred_x5c_ptr(cred) != NULL) { if ((r = fido_cred_verify(cred)) != FIDO_OK) { skdebug(__func__, "fido_cred_verify: %s", fido_strerr(r)); goto out; } } else { skdebug(__func__, "self-attested credential"); if ((r = fido_cred_verify_self(cred)) != FIDO_OK) { skdebug(__func__, "fido_cred_verify_self: %s", fido_strerr(r)); goto out; } } if ((response = calloc(1, sizeof(*response))) == NULL) { skdebug(__func__, "calloc response failed"); goto out; } response->flags = flags; if (pack_public_key(alg, cred, response) != 0) { skdebug(__func__, "pack_public_key failed"); goto out; } if ((ptr = fido_cred_id_ptr(cred)) != NULL) { len = fido_cred_id_len(cred); if ((response->key_handle = calloc(1, len)) == NULL) { skdebug(__func__, "calloc key handle failed"); goto out; } memcpy(response->key_handle, ptr, len); response->key_handle_len = len; } if ((ptr = fido_cred_sig_ptr(cred)) != NULL) { len = fido_cred_sig_len(cred); if ((response->signature = calloc(1, len)) == NULL) { skdebug(__func__, "calloc signature failed"); goto out; } memcpy(response->signature, ptr, len); response->signature_len = len; } if ((ptr = fido_cred_x5c_ptr(cred)) != NULL) { len = fido_cred_x5c_len(cred); skdebug(__func__, "attestation cert len=%zu", len); if ((response->attestation_cert = calloc(1, len)) == NULL) { skdebug(__func__, "calloc attestation cert failed"); goto out; } memcpy(response->attestation_cert, ptr, len); response->attestation_cert_len = len; } if ((ptr = fido_cred_authdata_ptr(cred)) != NULL) { len = fido_cred_authdata_len(cred); skdebug(__func__, "authdata len=%zu", len); if ((response->authdata = calloc(1, len)) == NULL) { skdebug(__func__, "calloc authdata failed"); goto out; } memcpy(response->authdata, ptr, len); response->authdata_len = len; } *enroll_response = response; response = NULL; ret = 0; out: free(device); if (response != NULL) { free(response->public_key); free(response->key_handle); free(response->signature); free(response->attestation_cert); free(response->authdata); free(response); } sk_close(sk); fido_cred_free(&cred); return ret; } #ifdef WITH_OPENSSL static int pack_sig_ecdsa(fido_assert_t *assert, struct sk_sign_response *response) { ECDSA_SIG *sig = NULL; const BIGNUM *sig_r, *sig_s; const unsigned char *cp; size_t sig_len; int ret = -1; cp = fido_assert_sig_ptr(assert, 0); sig_len = fido_assert_sig_len(assert, 0); if ((sig = d2i_ECDSA_SIG(NULL, &cp, sig_len)) == NULL) { skdebug(__func__, "d2i_ECDSA_SIG failed"); goto out; } ECDSA_SIG_get0(sig, &sig_r, &sig_s); response->sig_r_len = BN_num_bytes(sig_r); response->sig_s_len = BN_num_bytes(sig_s); if ((response->sig_r = calloc(1, response->sig_r_len)) == NULL || (response->sig_s = calloc(1, response->sig_s_len)) == NULL) { skdebug(__func__, "calloc signature failed"); goto out; } BN_bn2bin(sig_r, response->sig_r); BN_bn2bin(sig_s, response->sig_s); ret = 0; out: ECDSA_SIG_free(sig); if (ret != 0) { free(response->sig_r); free(response->sig_s); response->sig_r = NULL; response->sig_s = NULL; } return ret; } #endif /* WITH_OPENSSL */ static int pack_sig_ed25519(fido_assert_t *assert, struct sk_sign_response *response) { const unsigned char *ptr; size_t len; int ret = -1; ptr = fido_assert_sig_ptr(assert, 0); len = fido_assert_sig_len(assert, 0); if (len != 64) { skdebug(__func__, "bad length %zu", len); goto out; } response->sig_r_len = len; if ((response->sig_r = calloc(1, response->sig_r_len)) == NULL) { skdebug(__func__, "calloc signature failed"); goto out; } memcpy(response->sig_r, ptr, len); ret = 0; out: if (ret != 0) { free(response->sig_r); response->sig_r = NULL; } return ret; } static int pack_sig(uint32_t alg, fido_assert_t *assert, struct sk_sign_response *response) { switch(alg) { #ifdef WITH_OPENSSL case SSH_SK_ECDSA: return pack_sig_ecdsa(assert, response); #endif /* WITH_OPENSSL */ case SSH_SK_ED25519: return pack_sig_ed25519(assert, response); default: return -1; } } /* Checks sk_options for sk_sign() and sk_load_resident_keys() */ static int check_sign_load_resident_options(struct sk_option **options, char **devicep) { size_t i; if (options == NULL) return 0; for (i = 0; options[i] != NULL; i++) { if (strcmp(options[i]->name, "device") == 0) { if ((*devicep = strdup(options[i]->value)) == NULL) { skdebug(__func__, "strdup device failed"); return -1; } skdebug(__func__, "requested device %s", *devicep); } else { skdebug(__func__, "requested unsupported option %s", options[i]->name); if (options[i]->required) { skdebug(__func__, "unknown required option"); return -1; } } } return 0; } int sk_sign(uint32_t alg, const uint8_t *data, size_t datalen, const char *application, const uint8_t *key_handle, size_t key_handle_len, uint8_t flags, const char *pin, struct sk_option **options, struct sk_sign_response **sign_response) { fido_assert_t *assert = NULL; char *device = NULL; struct sk_usbhid *sk = NULL; struct sk_sign_response *response = NULL; int ret = SSH_SK_ERR_GENERAL, internal_uv; int r; fido_init(SSH_FIDO_INIT_ARG); if (sign_response == NULL) { skdebug(__func__, "sign_response == NULL"); goto out; } *sign_response = NULL; if (check_sign_load_resident_options(options, &device) != 0) goto out; /* error already logged */ if (device != NULL) sk = sk_open(device); else if (pin != NULL || (flags & SSH_SK_USER_VERIFICATION_REQD)) sk = sk_probe(NULL, NULL, 0, 0); else sk = sk_probe(application, key_handle, key_handle_len, 0); if (sk == NULL) { ret = SSH_SK_ERR_DEVICE_NOT_FOUND; skdebug(__func__, "failed to find sk"); goto out; } if ((assert = fido_assert_new()) == NULL) { skdebug(__func__, "fido_assert_new failed"); goto out; } if ((r = fido_assert_set_clientdata(assert, data, datalen)) != FIDO_OK) { skdebug(__func__, "fido_assert_set_clientdata: %s", fido_strerr(r)); goto out; } if ((r = fido_assert_set_rp(assert, application)) != FIDO_OK) { skdebug(__func__, "fido_assert_set_rp: %s", fido_strerr(r)); goto out; } if ((r = fido_assert_allow_cred(assert, key_handle, key_handle_len)) != FIDO_OK) { skdebug(__func__, "fido_assert_allow_cred: %s", fido_strerr(r)); goto out; } if ((r = fido_assert_set_up(assert, (flags & SSH_SK_USER_PRESENCE_REQD) ? FIDO_OPT_TRUE : FIDO_OPT_FALSE)) != FIDO_OK) { skdebug(__func__, "fido_assert_set_up: %s", fido_strerr(r)); goto out; } if (pin == NULL && (flags & SSH_SK_USER_VERIFICATION_REQD)) { if (check_sk_options(sk->dev, "uv", &internal_uv) < 0 || internal_uv != 1) { skdebug(__func__, "check_sk_options uv"); ret = SSH_SK_ERR_PIN_REQUIRED; goto out; } if ((r = fido_assert_set_uv(assert, FIDO_OPT_TRUE)) != FIDO_OK) { skdebug(__func__, "fido_assert_set_uv: %s", fido_strerr(r)); ret = fidoerr_to_skerr(r); goto out; } } if ((r = fido_dev_get_assert(sk->dev, assert, pin)) != FIDO_OK) { skdebug(__func__, "fido_dev_get_assert: %s", fido_strerr(r)); ret = fidoerr_to_skerr(r); goto out; } if ((response = calloc(1, sizeof(*response))) == NULL) { skdebug(__func__, "calloc response failed"); goto out; } response->flags = fido_assert_flags(assert, 0); response->counter = fido_assert_sigcount(assert, 0); if (pack_sig(alg, assert, response) != 0) { skdebug(__func__, "pack_sig failed"); goto out; } *sign_response = response; response = NULL; ret = 0; out: free(device); if (response != NULL) { free(response->sig_r); free(response->sig_s); free(response); } sk_close(sk); fido_assert_free(&assert); return ret; } static int read_rks(struct sk_usbhid *sk, const char *pin, struct sk_resident_key ***rksp, size_t *nrksp) { int ret = SSH_SK_ERR_GENERAL, r = -1, internal_uv; fido_credman_metadata_t *metadata = NULL; fido_credman_rp_t *rp = NULL; fido_credman_rk_t *rk = NULL; size_t i, j, nrp, nrk, user_id_len; const fido_cred_t *cred; const char *rp_id, *rp_name, *user_name; struct sk_resident_key *srk = NULL, **tmp; const u_char *user_id; if (pin == NULL) { skdebug(__func__, "no PIN specified"); ret = SSH_SK_ERR_PIN_REQUIRED; goto out; } if ((metadata = fido_credman_metadata_new()) == NULL) { skdebug(__func__, "alloc failed"); goto out; } if (check_sk_options(sk->dev, "uv", &internal_uv) != 0) { skdebug(__func__, "check_sk_options failed"); goto out; } if ((r = fido_credman_get_dev_metadata(sk->dev, metadata, pin)) != 0) { if (r == FIDO_ERR_INVALID_COMMAND) { skdebug(__func__, "device %s does not support " "resident keys", sk->path); ret = 0; goto out; } skdebug(__func__, "get metadata for %s failed: %s", sk->path, fido_strerr(r)); ret = fidoerr_to_skerr(r); goto out; } skdebug(__func__, "existing %llu, remaining %llu", (unsigned long long)fido_credman_rk_existing(metadata), (unsigned long long)fido_credman_rk_remaining(metadata)); if ((rp = fido_credman_rp_new()) == NULL) { skdebug(__func__, "alloc rp failed"); goto out; } if ((r = fido_credman_get_dev_rp(sk->dev, rp, pin)) != 0) { skdebug(__func__, "get RPs for %s failed: %s", sk->path, fido_strerr(r)); goto out; } nrp = fido_credman_rp_count(rp); skdebug(__func__, "Device %s has resident keys for %zu RPs", sk->path, nrp); /* Iterate over RP IDs that have resident keys */ for (i = 0; i < nrp; i++) { rp_id = fido_credman_rp_id(rp, i); rp_name = fido_credman_rp_name(rp, i); skdebug(__func__, "rp %zu: name=\"%s\" id=\"%s\" hashlen=%zu", i, rp_name == NULL ? "(none)" : rp_name, rp_id == NULL ? "(none)" : rp_id, fido_credman_rp_id_hash_len(rp, i)); /* Skip non-SSH RP IDs */ if (rp_id == NULL || strncasecmp(fido_credman_rp_id(rp, i), "ssh:", 4) != 0) continue; fido_credman_rk_free(&rk); if ((rk = fido_credman_rk_new()) == NULL) { skdebug(__func__, "alloc rk failed"); goto out; } if ((r = fido_credman_get_dev_rk(sk->dev, fido_credman_rp_id(rp, i), rk, pin)) != 0) { skdebug(__func__, "get RKs for %s slot %zu failed: %s", sk->path, i, fido_strerr(r)); goto out; } nrk = fido_credman_rk_count(rk); skdebug(__func__, "RP \"%s\" has %zu resident keys", fido_credman_rp_id(rp, i), nrk); /* Iterate over resident keys for this RP ID */ for (j = 0; j < nrk; j++) { if ((cred = fido_credman_rk(rk, j)) == NULL) { skdebug(__func__, "no RK in slot %zu", j); continue; } if ((user_name = fido_cred_user_name(cred)) == NULL) user_name = ""; user_id = fido_cred_user_id_ptr(cred); user_id_len = fido_cred_user_id_len(cred); skdebug(__func__, "Device %s RP \"%s\" user \"%s\" " "uidlen %zu slot %zu: type %d flags 0x%02x " "prot 0x%02x", sk->path, rp_id, user_name, user_id_len, j, fido_cred_type(cred), fido_cred_flags(cred), fido_cred_prot(cred)); /* build response entry */ if ((srk = calloc(1, sizeof(*srk))) == NULL || (srk->key.key_handle = calloc(1, fido_cred_id_len(cred))) == NULL || (srk->application = strdup(rp_id)) == NULL || (user_id_len > 0 && (srk->user_id = calloc(1, user_id_len)) == NULL)) { skdebug(__func__, "alloc sk_resident_key"); goto out; } srk->key.key_handle_len = fido_cred_id_len(cred); memcpy(srk->key.key_handle, fido_cred_id_ptr(cred), srk->key.key_handle_len); srk->user_id_len = user_id_len; if (srk->user_id_len != 0) memcpy(srk->user_id, user_id, srk->user_id_len); switch (fido_cred_type(cred)) { case COSE_ES256: srk->alg = SSH_SK_ECDSA; break; case COSE_EDDSA: srk->alg = SSH_SK_ED25519; break; default: skdebug(__func__, "unsupported key type %d", fido_cred_type(cred)); goto out; /* XXX free rk and continue */ } if (fido_cred_prot(cred) == FIDO_CRED_PROT_UV_REQUIRED && internal_uv == -1) srk->flags |= SSH_SK_USER_VERIFICATION_REQD; if ((r = pack_public_key(srk->alg, cred, &srk->key)) != 0) { skdebug(__func__, "pack public key failed"); goto out; } /* append */ if ((tmp = recallocarray(*rksp, *nrksp, (*nrksp) + 1, sizeof(**rksp))) == NULL) { skdebug(__func__, "alloc rksp"); goto out; } *rksp = tmp; (*rksp)[(*nrksp)++] = srk; srk = NULL; } } /* Success */ ret = 0; out: if (srk != NULL) { free(srk->application); freezero(srk->key.public_key, srk->key.public_key_len); freezero(srk->key.key_handle, srk->key.key_handle_len); freezero(srk->user_id, srk->user_id_len); freezero(srk, sizeof(*srk)); } fido_credman_rp_free(&rp); fido_credman_rk_free(&rk); fido_credman_metadata_free(&metadata); return ret; } int sk_load_resident_keys(const char *pin, struct sk_option **options, struct sk_resident_key ***rksp, size_t *nrksp) { int ret = SSH_SK_ERR_GENERAL, r = -1; size_t i, nrks = 0; struct sk_resident_key **rks = NULL; struct sk_usbhid *sk = NULL; char *device = NULL; *rksp = NULL; *nrksp = 0; fido_init(SSH_FIDO_INIT_ARG); if (check_sign_load_resident_options(options, &device) != 0) goto out; /* error already logged */ if (device != NULL) sk = sk_open(device); else sk = sk_probe(NULL, NULL, 0, 1); if (sk == NULL) { ret = SSH_SK_ERR_DEVICE_NOT_FOUND; skdebug(__func__, "failed to find sk"); goto out; } skdebug(__func__, "trying %s", sk->path); if ((r = read_rks(sk, pin, &rks, &nrks)) != 0) { skdebug(__func__, "read_rks failed for %s", sk->path); ret = r; goto out; } /* success, unless we have no keys but a specific error */ if (nrks > 0 || ret == SSH_SK_ERR_GENERAL) ret = 0; *rksp = rks; *nrksp = nrks; rks = NULL; nrks = 0; out: sk_close(sk); for (i = 0; i < nrks; i++) { free(rks[i]->application); freezero(rks[i]->key.public_key, rks[i]->key.public_key_len); freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len); freezero(rks[i]->user_id, rks[i]->user_id_len); freezero(rks[i], sizeof(*rks[i])); } free(device); free(rks); return ret; }