upstream: ssh client support for U2F/FIDO keys

OpenBSD-Commit-ID: eb2cfa6cf7419a1895e06e398ea6d41516c5b0bc

1 files changed, 86 insertions, 25 deletions

diff --git a/sshconnect2.c b/sshconnect2.c
index 87fa70a40..62f0c3e76 100644
--- a/sshconnect2.c
+++ b/sshconnect2.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect2.c,v 1.308 2019/08/05 11:50:33 dtucker Exp $ */
+/* $OpenBSD: sshconnect2.c,v 1.309 2019/10/31 21:18:28 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2008 Damien Miller.  All rights reserved.
@@ -72,6 +72,7 @@
 #include "hostfile.h"
 #include "ssherr.h"
 #include "utf8.h"
+#include "ssh-sk.h"
 
 #ifdef GSSAPI
 #include "ssh-gss.h"
@@ -601,17 +602,23 @@ static char *
 format_identity(Identity *id)
 {
         char *fp = NULL, *ret = NULL;
+        const char *note = "";
 
         if (id->key != NULL) {
              fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
                     SSH_FP_DEFAULT);
         }
+        if (id->key) {
+                if ((id->key->flags & SSHKEY_FLAG_EXT) != 0)
+                        note = " token";
+                else if (sshkey_type_plain(id->key->type) == KEY_ECDSA_SK)
+                        note = " security-key";
+        }
         xasprintf(&ret, "%s %s%s%s%s%s%s",
             id->filename,
             id->key ? sshkey_type(id->key) : "", id->key ? " " : "",
             fp ? fp : "",
-            id->userprovided ? " explicit" : "",
-            (id->key && (id->key->flags & SSHKEY_FLAG_EXT)) ? " token" : "",
+            id->userprovided ? " explicit" : "", note,
             id->agent_fd != -1 ? " agent" : "");
         free(fp);
         return ret;
@@ -1140,8 +1147,11 @@ static int
 identity_sign(struct identity *id, u_char **sigp, size_t *lenp,
     const u_char *data, size_t datalen, u_int compat, const char *alg)
 {
-        struct sshkey *prv;
-        int r;
+        struct sshkey *sign_key = NULL, *prv = NULL;
+        int r = SSH_ERR_INTERNAL_ERROR;
+
+        *sigp = NULL;
+        *lenp = 0;
 
         /* The agent supports this key. */
         if (id->key != NULL && id->agent_fd != -1) {
@@ -1155,27 +1165,46 @@ identity_sign(struct identity *id, u_char **sigp, size_t *lenp,
          */
         if (id->key != NULL &&
             (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) {
-                if ((r = sshkey_sign(id->key, sigp, lenp, data, datalen,
-                    alg, compat)) != 0)
-                        return r;
-                /*
-                 * PKCS#11 tokens may not support all signature algorithms,
-                 * so check what we get back.
-                 */
-                if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0)
-                        return r;
-                return 0;
+                sign_key = id->key;
+        } else {
+                /* Load the private key from the file. */
+                if ((prv = load_identity_file(id)) == NULL)
+                        return SSH_ERR_KEY_NOT_FOUND;
+                if (id->key != NULL && !sshkey_equal_public(prv, id->key)) {
+                        error("%s: private key %s contents do not match public",
+                           __func__, id->filename);
+                        r = SSH_ERR_KEY_NOT_FOUND;
+                        goto out;
+                }
+                sign_key = prv;
         }
 
-        /* Load the private key from the file. */
-        if ((prv = load_identity_file(id)) == NULL)
-                return SSH_ERR_KEY_NOT_FOUND;
-        if (id->key != NULL && !sshkey_equal_public(prv, id->key)) {
-                error("%s: private key %s contents do not match public",
-                   __func__, id->filename);
-                return SSH_ERR_KEY_NOT_FOUND;
+        if (sshkey_type_plain(sign_key->type) == KEY_ECDSA_SK) {
+                if (options.sk_provider == NULL) {
+                        /* Shouldn't happen here; checked in pubkey_prepare() */
+                        fatal("%s: missing SecurityKeyProvider", __func__);
+                }
+                if ((r = sshsk_ecdsa_sign(options.sk_provider, sign_key,
+                    sigp, lenp, data, datalen, compat)) != 0) {
+                        debug("%s: sshsk_ecdsa_sign: %s", __func__, ssh_err(r));
+                        goto out;
+                }
+        } else if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen,
+            alg, compat)) != 0) {
+                debug("%s: sshkey_sign: %s", __func__, ssh_err(r));
+                goto out;
         }
-        r = sshkey_sign(prv, sigp, lenp, data, datalen, alg, compat);
+        /*
+         * PKCS#11 tokens may not support all signature algorithms,
+         * so check what we get back.
+         */
+        if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) {
+                debug("%s: sshkey_check_sigtype: %s", __func__, ssh_err(r));
+                goto out;
+        }
+        /* success */
+        r = 0;
+ out:
         sshkey_free(prv);
         return r;
 }
@@ -1450,6 +1479,15 @@ load_identity_file(Identity *id)
                         quit = 1;
                         break;
                 }
+                if (private != NULL &&
+                    sshkey_type_plain(private->type) == KEY_ECDSA_SK &&
+                    options.sk_provider == NULL) {
+                        debug("key \"%s\" is a security key, but no "
+                            "provider specified", id->filename);
+                        sshkey_free(private);
+                        private = NULL;
+                        quit = 1;
+                }
                 if (!quit && private != NULL && id->agent_fd == -1 &&
                     !(id->key && id->isprivate))
                         maybe_add_key_to_agent(id->filename, private, comment,
@@ -1520,8 +1558,20 @@ pubkey_prepare(Authctxt *authctxt)
         /* list of keys stored in the filesystem and PKCS#11 */
         for (i = 0; i < options.num_identity_files; i++) {
                 key = options.identity_keys[i];
-                if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
+                if (key && key->cert &&
+                    key->cert->type != SSH2_CERT_TYPE_USER) {
+                        debug("%s: ignoring certificate %s: not a user "
+                            "certificate",  __func__,
+                            options.identity_files[i]);
+                        continue;
+                }
+                if (key && sshkey_type_plain(key->type) == KEY_ECDSA_SK &&
+                    options.sk_provider == NULL) {
+                        debug("%s: ignoring security key %s as no "
+                            "SecurityKeyProvider has been specified",
+                            __func__, options.identity_files[i]);
                         continue;
+                }
                 options.identity_keys[i] = NULL;
                 id = xcalloc(1, sizeof(*id));
                 id->agent_fd = -1;
@@ -1534,8 +1584,19 @@ pubkey_prepare(Authctxt *authctxt)
         for (i = 0; i < options.num_certificate_files; i++) {
                 key = options.certificates[i];
                 if (!sshkey_is_cert(key) || key->cert == NULL ||
-                    key->cert->type != SSH2_CERT_TYPE_USER)
+                    key->cert->type != SSH2_CERT_TYPE_USER) {
+                        debug("%s: ignoring certificate %s: not a user "
+                            "certificate",  __func__,
+                            options.identity_files[i]);
                         continue;
+                }
+                if (key && sshkey_type_plain(key->type) == KEY_ECDSA_SK &&
+                    options.sk_provider == NULL) {
+                        debug("%s: ignoring security key certificate %s as no "
+                            "SecurityKeyProvider has been specified",
+                            __func__, options.identity_files[i]);
+                        continue;
+                }
                 id = xcalloc(1, sizeof(*id));
                 id->agent_fd = -1;
                 id->key = key;