upstream: allow security keys to act as host keys as well as user

keys.

Previously we didn't do this because we didn't want to expose
the attack surface presented by USB and FIDO protocol handling,
but now that this is insulated behind ssh-sk-helper there is
less risk.

ok markus@

OpenBSD-Commit-ID: 77b068dd133b8d87e0f010987bd5131e640ee64c

1 files changed, 14 insertions, 4 deletions

diff --git a/servconf.c b/servconf.c
index 1f3beab4a..30cd59840 100644
--- a/servconf.c
+++ b/servconf.c
@@ -1,5 +1,5 @@
 
-/* $OpenBSD: servconf.c,v 1.354 2019/11/25 00:52:46 djm Exp $ */
+/* $OpenBSD: servconf.c,v 1.355 2019/12/15 18:57:30 djm Exp $ */
 /*
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
@@ -171,6 +171,7 @@ initialize_server_options(ServerOptions *options)
         options->authorized_keys_command = NULL;
         options->authorized_keys_command_user = NULL;
         options->revoked_keys_file = NULL;
+        options->sk_provider = NULL;
         options->trusted_user_ca_keys = NULL;
         options->authorized_principals_file = NULL;
         options->authorized_principals_command = NULL;
@@ -211,7 +212,7 @@ assemble_algorithms(ServerOptions *o)
         ASSEMBLE(kex_algorithms, KEX_SERVER_KEX, all_kex);
         ASSEMBLE(hostkeyalgorithms, KEX_DEFAULT_PK_ALG, all_key);
         ASSEMBLE(hostbased_key_types, KEX_DEFAULT_PK_ALG, all_key);
-        ASSEMBLE(pubkey_key_types, PUBKEY_DEFAULT_PK_ALG, all_key);
+        ASSEMBLE(pubkey_key_types, KEX_DEFAULT_PK_ALG, all_key);
         ASSEMBLE(ca_sign_algorithms, SSH_ALLOWED_CA_SIGALGS, all_sig);
 #undef ASSEMBLE
         free(all_cipher);
@@ -428,6 +429,8 @@ fill_default_server_options(ServerOptions *options)
                 options->disable_forwarding = 0;
         if (options->expose_userauth_info == -1)
                 options->expose_userauth_info = 0;
+        if (options->sk_provider == NULL)
+                options->sk_provider = xstrdup("internal");
 
         assemble_algorithms(options);
 
@@ -447,6 +450,7 @@ fill_default_server_options(ServerOptions *options)
         CLEAR_ON_NONE(options->banner);
         CLEAR_ON_NONE(options->trusted_user_ca_keys);
         CLEAR_ON_NONE(options->revoked_keys_file);
+        CLEAR_ON_NONE(options->sk_provider);
         CLEAR_ON_NONE(options->authorized_principals_file);
         CLEAR_ON_NONE(options->adm_forced_command);
         CLEAR_ON_NONE(options->chroot_directory);
@@ -512,7 +516,7 @@ typedef enum {
         sAuthenticationMethods, sHostKeyAgent, sPermitUserRC,
         sStreamLocalBindMask, sStreamLocalBindUnlink,
         sAllowStreamLocalForwarding, sFingerprintHash, sDisableForwarding,
-        sExposeAuthInfo, sRDomain, sPubkeyAuthOptions,
+        sExposeAuthInfo, sRDomain, sPubkeyAuthOptions, sSecurityKeyProvider,
         sDeprecated, sIgnore, sUnsupported
 } ServerOpCodes;
 
@@ -662,6 +666,7 @@ static struct {
         { "exposeauthinfo", sExposeAuthInfo, SSHCFG_ALL },
         { "rdomain", sRDomain, SSHCFG_ALL },
         { "casignaturealgorithms", sCASignatureAlgorithms, SSHCFG_ALL },
+        { "securitykeyprovider", sSecurityKeyProvider, SSHCFG_GLOBAL },
         { NULL, sBadOption, 0 }
 };
 
@@ -2025,6 +2030,10 @@ process_server_config_line(ServerOptions *options, char *line,
                 charptr = &options->revoked_keys_file;
                 goto parse_filename;
 
+        case sSecurityKeyProvider:
+                charptr = &options->sk_provider;
+                goto parse_filename;
+
         case sIPQoS:
                 arg = strdelim(&cp);
                 if ((value = parse_ipqos(arg)) == -1)
@@ -2646,6 +2655,7 @@ dump_config(ServerOptions *o)
         dump_cfg_string(sChrootDirectory, o->chroot_directory);
         dump_cfg_string(sTrustedUserCAKeys, o->trusted_user_ca_keys);
         dump_cfg_string(sRevokedKeys, o->revoked_keys_file);
+        dump_cfg_string(sSecurityKeyProvider, o->sk_provider);
         dump_cfg_string(sAuthorizedPrincipalsFile,
             o->authorized_principals_file);
         dump_cfg_string(sVersionAddendum, *o->version_addendum == '\0'
@@ -2664,7 +2674,7 @@ dump_config(ServerOptions *o)
         dump_cfg_string(sHostKeyAlgorithms, o->hostkeyalgorithms ?
             o->hostkeyalgorithms : KEX_DEFAULT_PK_ALG);
         dump_cfg_string(sPubkeyAcceptedKeyTypes, o->pubkey_key_types ?
-            o->pubkey_key_types : PUBKEY_DEFAULT_PK_ALG);
+            o->pubkey_key_types : KEX_DEFAULT_PK_ALG);
         dump_cfg_string(sRDomain, o->routing_domain);
 
         /* string arguments requiring a lookup */