upstream: use libfido2 1.8.0+ fido_assert_set_clientdata() instead

of manually hashing data outselves. Saves a fair bit of code and makes life
easier for some -portable platforms.

OpenBSD-Commit-ID: 351dfaaa5ab1ee928c0e623041fca28078cff0e0

diff --git a/configure.ac b/configure.ac
index eb265143ba705b40d22341768e5566a5a6f254c1..f2a4aa12bc042e86773822a7b2247023922604e3 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -3232,6 +3232,7 @@ if test "x$enable_sk" = "xyes" -a "x$enable_sk_internal" = "xyes" ; then
        AC_CHECK_FUNCS([ \
                fido_cred_prot \
                fido_cred_set_prot \
+               fido_cred_set_clientdata \
                fido_dev_get_touch_begin \
                fido_dev_get_touch_status \
                fido_dev_supports_cred_prot \

diff --git a/sk-usbhid.c b/sk-usbhid.c
index 7e4d1d55adc613fcea8a77c43dbe29b747772427..d01dd29241eb9ad8fdbc2907ba0882b61eb4cbea 100644 (file)
--- a/sk-usbhid.c
+++ b/sk-usbhid.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sk-usbhid.c,v 1.37 2021/12/07 22:06:45 djm Exp $ */
+/* $OpenBSD: sk-usbhid.c,v 1.38 2022/02/07 01:25:12 djm Exp $ */
 /*
  * Copyright (c) 2019 Markus Friedl
  * Copyright (c) 2020 Pedro Martelletto
@@ -312,6 +312,7 @@ sk_touch_poll(struct sk_usbhid **skv, size_t nsk, int *touch, size_t *idx)
        return 0;
 }
 
+#ifndef HAVE_FIDO_CRED_SET_CLIENTDATA
 /* Calculate SHA256(m) */
 static int
 sha256_mem(const void *m, size_t mlen, u_char *d, size_t dlen)
@@ -336,26 +337,42 @@ sha256_mem(const void *m, size_t mlen, u_char *d, size_t dlen)
        return 0;
 }
 
+int
+fido_cred_set_clientdata(fido_cred_t *cred, const u_char *ptr, size_t len)
+{
+       uint8_t d[32];
+       int r;
+
+       if (sha256_mem(ptr, len, d, sizeof(d)) != 0) {
+               skdebug(__func__, "hash challenge failed");
+               return FIDO_ERR_INTERNAL;
+       }
+       r = fido_cred_set_clientdata_hash(cred, d, sizeof(d));
+       explicit_bzero(d, sizeof(d));
+       if (r != FIDO_OK) {
+               skdebug(__func__, "fido_cred_set_clientdata_hash failed: %s",
+                   fido_strerr(r));
+       }
+       return r;
+}
+#endif /* HAVE_FIDO_CRED_SET_CLIENTDATA */
+
 /* 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;
-       /* generate an invalid signature on FIDO2 tokens */
-       const char *data = "";
-       uint8_t message[32];
        int r = FIDO_ERR_INTERNAL;
+       uint8_t message[32];
 
-       if (sha256_mem(data, strlen(data), message, sizeof(message)) != 0) {
-               skdebug(__func__, "hash message failed");
-               goto out;
-       }
+       memset(message, '\0', sizeof(message));
        if ((assert = fido_assert_new()) == NULL) {
                skdebug(__func__, "fido_assert_new failed");
                goto out;
        }
-       if ((r = fido_assert_set_clientdata_hash(assert, message,
+       /* 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_hash: %s",
                    fido_strerr(r));
@@ -730,7 +747,7 @@ sk_enroll(uint32_t alg, const uint8_t *challenge, size_t challenge_len,
 {
        fido_cred_t *cred = NULL;
        const uint8_t *ptr;
-       uint8_t user_id[32], chall_hash[32];
+       uint8_t user_id[32];
        struct sk_usbhid *sk = NULL;
        struct sk_enroll_response *response = NULL;
        size_t len;
@@ -784,14 +801,9 @@ sk_enroll(uint32_t alg, const uint8_t *challenge, size_t challenge_len,
                skdebug(__func__, "fido_cred_set_type: %s", fido_strerr(r));
                goto out;
        }
-       if (sha256_mem(challenge, challenge_len,
-           chall_hash, sizeof(chall_hash)) != 0) {
-               skdebug(__func__, "hash challenge failed");
-               goto out;
-       }
-       if ((r = fido_cred_set_clientdata_hash(cred, chall_hash,
-           sizeof(chall_hash))) != FIDO_OK) {
-               skdebug(__func__, "fido_cred_set_clientdata_hash: %s",
+       if ((r = fido_cred_set_clientdata(cred,
+           challenge, challenge_len)) != FIDO_OK) {
+               skdebug(__func__, "fido_cred_set_clientdata: %s",
                    fido_strerr(r));
                goto out;
        }
@@ -1048,7 +1060,6 @@ sk_sign(uint32_t alg, const uint8_t *data, size_t datalen,
        char *device = NULL;
        struct sk_usbhid *sk = NULL;
        struct sk_sign_response *response = NULL;
-       uint8_t message[32];
        int ret = SSH_SK_ERR_GENERAL, internal_uv;
        int r;
 
@@ -1061,11 +1072,6 @@ sk_sign(uint32_t alg, const uint8_t *data, size_t datalen,
        *sign_response = NULL;
        if (check_sign_load_resident_options(options, &device) != 0)
                goto out; /* error already logged */
-       /* hash data to be signed before it goes to the security key */
-       if ((r = sha256_mem(data, datalen, message, sizeof(message))) != 0) {
-               skdebug(__func__, "hash message failed");
-               goto out;
-       }
        if (device != NULL)
                sk = sk_open(device);
        else if (pin != NULL || (flags & SSH_SK_USER_VERIFICATION_REQD))
@@ -1081,9 +1087,9 @@ sk_sign(uint32_t alg, const uint8_t *data, size_t datalen,
                skdebug(__func__, "fido_assert_new failed");
                goto out;
        }
-       if ((r = fido_assert_set_clientdata_hash(assert, message,
-           sizeof(message))) != FIDO_OK) {
-               skdebug(__func__, "fido_assert_set_clientdata_hash: %s",
+       if ((r = fido_assert_set_clientdata(assert,
+           data, datalen)) != FIDO_OK)  {
+               skdebug(__func__, "fido_assert_set_clientdata: %s",
                    fido_strerr(r));
                goto out;
        }
@@ -1136,7 +1142,6 @@ sk_sign(uint32_t alg, const uint8_t *data, size_t datalen,
        response = NULL;
        ret = 0;
  out:
-       explicit_bzero(message, sizeof(message));
        free(device);
        if (response != NULL) {
                free(response->sig_r);