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openssh-portable/sk-usbhid.c

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/*
* Copyright (c) 2019 Markus Friedl
*
* 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"
#ifdef ENABLE_SK_INTERNAL
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <stddef.h>
#include <stdarg.h>
#ifdef WITH_OPENSSL
#include <openssl/opensslv.h>
#include <openssl/crypto.h>
#include <openssl/bn.h>
#include <openssl/ec.h>
#include <openssl/ecdsa.h>
#endif /* WITH_OPENSSL */
#include <fido.h>
#include <fido/credman.h>
#ifndef SK_STANDALONE
#include "log.h"
#include "xmalloc.h"
#endif
/* #define SK_DEBUG 1 */
#define MAX_FIDO_DEVICES 256
/* Compatibility with OpenSSH 1.0.x */
#if (OPENSSL_VERSION_NUMBER < 0x10100000L)
#define ECDSA_SIG_get0(sig, pr, ps) \
do { \
(*pr) = sig->r; \
(*ps) = sig->s; \
} while (0)
#endif
#define SK_VERSION_MAJOR 0x00040000 /* current API version */
/* Flags */
#define SK_USER_PRESENCE_REQD 0x01
#define SK_USER_VERIFICATION_REQD 0x04
#define SK_RESIDENT_KEY 0x20
/* Algs */
#define SK_ECDSA 0x00
#define SK_ED25519 0x01
/* Error codes */
#define SSH_SK_ERR_GENERAL -1
#define SSH_SK_ERR_UNSUPPORTED -2
#define SSH_SK_ERR_PIN_REQUIRED -3
struct sk_enroll_response {
uint8_t *public_key;
size_t public_key_len;
uint8_t *key_handle;
size_t key_handle_len;
uint8_t *signature;
size_t signature_len;
uint8_t *attestation_cert;
size_t attestation_cert_len;
};
struct sk_sign_response {
uint8_t flags;
uint32_t counter;
uint8_t *sig_r;
size_t sig_r_len;
uint8_t *sig_s;
size_t sig_s_len;
};
struct sk_resident_key {
uint32_t alg;
size_t slot;
char *application;
struct sk_enroll_response key;
};
struct sk_option {
char *name;
char *value;
uint8_t required;
};
/* If building as part of OpenSSH, then rename exported functions */
#if !defined(SK_STANDALONE)
#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
/* 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 *message, size_t message_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 SK_VERSION_MAJOR;
}
/* Select the first identified FIDO device attached to the system */
static char *
pick_first_device(void)
{
char *ret = NULL;
fido_dev_info_t *devlist = NULL;
size_t olen = 0;
int r;
const fido_dev_info_t *di;
if ((devlist = fido_dev_info_new(1)) == NULL) {
skdebug(__func__, "fido_dev_info_new failed");
goto out;
}
if ((r = fido_dev_info_manifest(devlist, 1, &olen)) != FIDO_OK) {
skdebug(__func__, "fido_dev_info_manifest failed: %s",
fido_strerr(r));
goto out;
}
if (olen != 1) {
skdebug(__func__, "fido_dev_info_manifest bad len %zu", olen);
goto out;
}
di = fido_dev_info_ptr(devlist, 0);
if ((ret = strdup(fido_dev_info_path(di))) == NULL) {
skdebug(__func__, "fido_dev_info_path failed");
goto out;
}
out:
fido_dev_info_free(&devlist, 1);
return ret;
}
/* Check if the specified key handle exists on a given device. */
static int
try_device(fido_dev_t *dev, const uint8_t *message, size_t message_len,
const char *application, const uint8_t *key_handle, size_t key_handle_len)
{
fido_assert_t *assert = NULL;
int r = FIDO_ERR_INTERNAL;
if ((assert = fido_assert_new()) == NULL) {
skdebug(__func__, "fido_assert_new failed");
goto out;
}
if ((r = fido_assert_set_clientdata_hash(assert, message,
message_len)) != FIDO_OK) {
skdebug(__func__, "fido_assert_set_clientdata_hash: %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(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;
}
/* Iterate over configured devices looking for a specific key handle */
static fido_dev_t *
find_device(const char *path, const uint8_t *message, size_t message_len,
const char *application, const uint8_t *key_handle, size_t key_handle_len)
{
fido_dev_info_t *devlist = NULL;
fido_dev_t *dev = NULL;
size_t devlist_len = 0, i;
int r;
if (path != NULL) {
if ((dev = fido_dev_new()) == NULL) {
skdebug(__func__, "fido_dev_new failed");
return NULL;
}
if ((r = fido_dev_open(dev, path)) != FIDO_OK) {
skdebug(__func__, "fido_dev_open failed");
fido_dev_free(&dev);
return NULL;
}
return dev;
}
if ((devlist = fido_dev_info_new(MAX_FIDO_DEVICES)) == NULL) {
skdebug(__func__, "fido_dev_info_new failed");
goto out;
}
if ((r = fido_dev_info_manifest(devlist, MAX_FIDO_DEVICES,
&devlist_len)) != FIDO_OK) {
skdebug(__func__, "fido_dev_info_manifest: %s", fido_strerr(r));
goto out;
}
skdebug(__func__, "found %zu device(s)", devlist_len);
for (i = 0; i < devlist_len; i++) {
const fido_dev_info_t *di = fido_dev_info_ptr(devlist, i);
if (di == NULL) {
skdebug(__func__, "fido_dev_info_ptr %zu failed", i);
continue;
}
if ((path = fido_dev_info_path(di)) == NULL) {
skdebug(__func__, "fido_dev_info_path %zu failed", i);
continue;
}
skdebug(__func__, "trying device %zu: %s", i, path);
if ((dev = fido_dev_new()) == NULL) {
skdebug(__func__, "fido_dev_new failed");
continue;
}
if ((r = fido_dev_open(dev, path)) != FIDO_OK) {
skdebug(__func__, "fido_dev_open failed");
fido_dev_free(&dev);
continue;
}
if (try_device(dev, message, message_len, application,
key_handle, key_handle_len) == 0) {
skdebug(__func__, "found key");
break;
}
fido_dev_close(dev);
fido_dev_free(&dev);
}
out:
if (devlist != NULL)
fido_dev_info_free(&devlist, MAX_FIDO_DEVICES);
return dev;
}
#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 SK_ECDSA:
return pack_public_key_ecdsa(cred, response);
#endif /* WITH_OPENSSL */
case 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:
return SSH_SK_ERR_UNSUPPORTED;
case FIDO_ERR_PIN_REQUIRED:
case FIDO_ERR_PIN_INVALID:
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(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;
}
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;
fido_dev_t *dev = NULL;
const uint8_t *ptr;
uint8_t user_id[32];
struct sk_enroll_response *response = NULL;
size_t len;
int cose_alg;
int ret = SSH_SK_ERR_GENERAL;
int r;
char *device = NULL;
#ifdef SK_DEBUG
fido_init(FIDO_DEBUG);
#endif
if (enroll_response == NULL) {
skdebug(__func__, "enroll_response == NULL");
goto out;
}
memset(user_id, 0, sizeof(user_id));
if (check_enroll_options(options, &device,
user_id, sizeof(user_id)) != 0)
goto out; /* error already logged */
*enroll_response = NULL;
switch(alg) {
#ifdef WITH_OPENSSL
case SK_ECDSA:
cose_alg = COSE_ES256;
break;
#endif /* WITH_OPENSSL */
case SK_ED25519:
cose_alg = COSE_EDDSA;
break;
default:
skdebug(__func__, "unsupported key type %d", alg);
goto out;
}
if (device == NULL && (device = pick_first_device()) == NULL) {
skdebug(__func__, "pick_first_device failed");
goto out;
}
skdebug(__func__, "using device %s", device);
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_hash(cred, challenge,
challenge_len)) != FIDO_OK) {
skdebug(__func__, "fido_cred_set_clientdata_hash: %s",
fido_strerr(r));
goto out;
}
if ((r = fido_cred_set_rk(cred, (flags & 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 ((dev = fido_dev_new()) == NULL) {
skdebug(__func__, "fido_dev_new failed");
goto out;
}
if ((r = fido_dev_open(dev, device)) != FIDO_OK) {
skdebug(__func__, "fido_dev_open: %s", fido_strerr(r));
goto out;
}
if ((r = fido_dev_make_cred(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;
}
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);
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;
}
*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);
}
if (dev != NULL) {
fido_dev_close(dev);
fido_dev_free(&dev);
}
if (cred != NULL) {
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 SK_ECDSA:
return pack_sig_ecdsa(assert, response);
#endif /* WITH_OPENSSL */
case 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 *message, size_t message_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)
{
fido_assert_t *assert = NULL;
char *device = NULL;
fido_dev_t *dev = NULL;
struct sk_sign_response *response = NULL;
int ret = SSH_SK_ERR_GENERAL;
int r;
#ifdef SK_DEBUG
fido_init(FIDO_DEBUG);
#endif
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 ((dev = find_device(device, message, message_len,
application, key_handle, key_handle_len)) == NULL) {
skdebug(__func__, "couldn't find device for key handle");
goto out;
}
if ((assert = fido_assert_new()) == NULL) {
skdebug(__func__, "fido_assert_new failed");
goto out;
}
if ((r = fido_assert_set_clientdata_hash(assert, message,
message_len)) != FIDO_OK) {
skdebug(__func__, "fido_assert_set_clientdata_hash: %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 & 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 ((r = fido_dev_get_assert(dev, assert, NULL)) != FIDO_OK) {
skdebug(__func__, "fido_dev_get_assert: %s", fido_strerr(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);
}
if (dev != NULL) {
fido_dev_close(dev);
fido_dev_free(&dev);
}
if (assert != NULL) {
fido_assert_free(&assert);
}
return ret;
}
static int
read_rks(const char *devpath, const char *pin,
struct sk_resident_key ***rksp, size_t *nrksp)
{
int ret = SSH_SK_ERR_GENERAL, r = -1;
fido_dev_t *dev = NULL;
fido_credman_metadata_t *metadata = NULL;
fido_credman_rp_t *rp = NULL;
fido_credman_rk_t *rk = NULL;
size_t i, j, nrp, nrk;
const fido_cred_t *cred;
struct sk_resident_key *srk = NULL, **tmp;
if ((dev = fido_dev_new()) == NULL) {
skdebug(__func__, "fido_dev_new failed");
return ret;
}
if ((r = fido_dev_open(dev, devpath)) != FIDO_OK) {
skdebug(__func__, "fido_dev_open %s failed: %s",
devpath, fido_strerr(r));
fido_dev_free(&dev);
return ret;
}
if ((metadata = fido_credman_metadata_new()) == NULL) {
skdebug(__func__, "alloc failed");
goto out;
}
if ((r = fido_credman_get_dev_metadata(dev, metadata, pin)) != 0) {
if (r == FIDO_ERR_INVALID_COMMAND) {
skdebug(__func__, "device %s does not support "
"resident keys", devpath);
ret = 0;
goto out;
}
skdebug(__func__, "get metadata for %s failed: %s",
devpath, 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(dev, rp, pin)) != 0) {
skdebug(__func__, "get RPs for %s failed: %s",
devpath, fido_strerr(r));
goto out;
}
nrp = fido_credman_rp_count(rp);
skdebug(__func__, "Device %s has resident keys for %zu RPs",
devpath, nrp);
/* Iterate over RP IDs that have resident keys */
for (i = 0; i < nrp; i++) {
skdebug(__func__, "rp %zu: name=\"%s\" id=\"%s\" hashlen=%zu",
i, fido_credman_rp_name(rp, i), fido_credman_rp_id(rp, i),
fido_credman_rp_id_hash_len(rp, i));
/* Skip non-SSH RP IDs */
if (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(dev, fido_credman_rp_id(rp, i),
rk, pin)) != 0) {
skdebug(__func__, "get RKs for %s slot %zu failed: %s",
devpath, 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;
}
skdebug(__func__, "Device %s RP \"%s\" slot %zu: "
"type %d", devpath, fido_credman_rp_id(rp, i), j,
fido_cred_type(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(fido_credman_rp_id(rp,
i))) == 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);
switch (fido_cred_type(cred)) {
case COSE_ES256:
srk->alg = SK_ECDSA;
break;
case COSE_EDDSA:
srk->alg = SK_ED25519;
break;
default:
skdebug(__func__, "unsupported key type %d",
fido_cred_type(cred));
goto out;
}
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, sizeof(*srk));
}
fido_credman_rp_free(&rp);
fido_credman_rk_free(&rk);
fido_dev_close(dev);
fido_dev_free(&dev);
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;
fido_dev_info_t *devlist = NULL;
size_t i, ndev = 0, nrks = 0;
const fido_dev_info_t *di;
struct sk_resident_key **rks = NULL;
char *device = NULL;
*rksp = NULL;
*nrksp = 0;
if (check_sign_load_resident_options(options, &device) != 0)
goto out; /* error already logged */
if (device != NULL) {
skdebug(__func__, "trying %s", device);
if ((r = read_rks(device, pin, &rks, &nrks)) != 0) {
skdebug(__func__, "read_rks failed for %s", device);
ret = r;
goto out;
}
} else {
/* Try all devices */
if ((devlist = fido_dev_info_new(MAX_FIDO_DEVICES)) == NULL) {
skdebug(__func__, "fido_dev_info_new failed");
goto out;
}
if ((r = fido_dev_info_manifest(devlist,
MAX_FIDO_DEVICES, &ndev)) != FIDO_OK) {
skdebug(__func__, "fido_dev_info_manifest failed: %s",
fido_strerr(r));
goto out;
}
for (i = 0; i < ndev; i++) {
if ((di = fido_dev_info_ptr(devlist, i)) == NULL) {
skdebug(__func__, "no dev info at %zu", i);
continue;
}
skdebug(__func__, "trying %s", fido_dev_info_path(di));
if ((r = read_rks(fido_dev_info_path(di), pin,
&rks, &nrks)) != 0) {
skdebug(__func__, "read_rks failed for %s",
fido_dev_info_path(di));
/* remember last error */
ret = r;
continue;
}
}
}
/* 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:
free(device);
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], sizeof(*rks[i]));
}
free(rks);
fido_dev_info_free(&devlist, MAX_FIDO_DEVICES);
return ret;
}
#endif /* ENABLE_SK_INTERNAL */
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