-/*************************************************
-* Exim - an Internet mail transport agent *
-*************************************************/
-
-/* Copyright (c) The Exim Maintainers 2019 - 2022 */
-/* Copyright (c) University of Cambridge 1995 - 2018 */
-/* See the file NOTICE for conditions of use and distribution. */
-/* SPDX-License-Identifier: GPL-2.0-or-later */
-
-/* Copyright (c) Twitter Inc 2012
- Author: Phil Pennock <pdp@exim.org> */
-/* Copyright (c) Phil Pennock 2012 */
-
-/* Interface to GNU SASL library for generic authentication. */
-
-/* Trade-offs:
-
-GNU SASL does not provide authentication data itself, so we have to expose
-that decision to configuration. For some mechanisms, we need to act much
-like plaintext. For others, we only need to be able to provide some
-evaluated data on demand. There's no abstracted way (ie, without hardcoding
-knowledge of authenticators here) to know which need what properties; we
-can't query a session or the library for "we will need these for mechanism X".
-
-So: we always require server_condition, even if sometimes it will just be
-set as "yes". We do provide a number of other hooks, which might not make
-sense in all contexts. For some, we can do checks at init time.
-*/
-
-#include "../exim.h"
-
-#ifndef AUTH_GSASL
-/* dummy function to satisfy compilers when we link in an "empty" file. */
-static void dummy(int x);
-static void dummy2(int x) { dummy(x-1); }
-static void dummy(int x) { dummy2(x-1); }
-#else
-
-#include <gsasl.h>
-#include "gsasl_exim.h"
-
-
-#if GSASL_VERSION_MAJOR == 2
-
-# define EXIM_GSASL_HAVE_SCRAM_SHA_256
-# define EXIM_GSASL_SCRAM_S_KEY
-# if GSASL_VERSION_MINOR >= 1
-# define EXIM_GSASL_HAVE_EXPORTER
-# elif GSASL_VERSION_PATCH >= 1
-# define EXIM_GSASL_HAVE_EXPORTER
-# endif
-
-#elif GSASL_VERSION_MAJOR == 1
-# if GSASL_VERSION_MINOR >= 10
-# define EXIM_GSASL_HAVE_SCRAM_SHA_256
-# define EXIM_GSASL_SCRAM_S_KEY
-
-# elif GSASL_VERSION_MINOR == 9
-# define EXIM_GSASL_HAVE_SCRAM_SHA_256
-
-# if GSASL_VERSION_PATCH >= 1
-# define EXIM_GSASL_SCRAM_S_KEY
-# endif
-# if GSASL_VERSION_PATCH < 2
-# define CHANNELBIND_HACK
-# endif
-
-# else
-# define CHANNELBIND_HACK
-# endif
-#endif
-
-/* Convenience for testing strings */
-
-#define STREQIC(Foo, Bar) (strcmpic((Foo), (Bar)) == 0)
-
-
-/* Authenticator-specific options. */
-/* I did have server_*_condition options for various mechanisms, but since
-we only ever handle one mechanism at a time, I didn't see the point in keeping
-that. In case someone sees a point, I've left the condition_check() API
-alone. */
-#define LOFF(field) OPT_OFF(auth_gsasl_options_block, field)
-
-optionlist auth_gsasl_options[] = {
- { "client_authz", opt_stringptr, LOFF(client_authz) },
- { "client_channelbinding", opt_bool, LOFF(client_channelbinding) },
- { "client_password", opt_stringptr, LOFF(client_password) },
- { "client_spassword", opt_stringptr, LOFF(client_spassword) },
- { "client_username", opt_stringptr, LOFF(client_username) },
-
- { "server_channelbinding", opt_bool, LOFF(server_channelbinding) },
- { "server_hostname", opt_stringptr, LOFF(server_hostname) },
-#ifdef EXIM_GSASL_SCRAM_S_KEY
- { "server_key", opt_stringptr, LOFF(server_key) },
-#endif
- { "server_mech", opt_stringptr, LOFF(server_mech) },
- { "server_password", opt_stringptr, LOFF(server_password) },
- { "server_realm", opt_stringptr, LOFF(server_realm) },
- { "server_scram_iter", opt_stringptr, LOFF(server_scram_iter) },
- { "server_scram_salt", opt_stringptr, LOFF(server_scram_salt) },
-#ifdef EXIM_GSASL_SCRAM_S_KEY
- { "server_skey", opt_stringptr, LOFF(server_s_key) },
-#endif
- { "server_service", opt_stringptr, LOFF(server_service) }
-};
-
-int auth_gsasl_options_count =
- sizeof(auth_gsasl_options)/sizeof(optionlist);
-
-/* Defaults for the authenticator-specific options. */
-auth_gsasl_options_block auth_gsasl_option_defaults = {
- .server_service = US"smtp",
- .server_hostname = US"$primary_hostname",
- .server_scram_iter = US"4096",
- /* all others zero/null */
-};
-
-
-#ifdef MACRO_PREDEF
-# include "../macro_predef.h"
-
-/* Dummy values */
-void auth_gsasl_init(auth_instance *ablock) {}
-int auth_gsasl_server(auth_instance *ablock, uschar *data) {return 0;}
-int auth_gsasl_client(auth_instance *ablock, void * sx,
- int timeout, uschar *buffer, int buffsize) {return 0;}
-gstring * auth_gsasl_version_report(gstring * g) {return NULL;}
-
-void
-auth_gsasl_macros(void)
-{
-# ifdef EXIM_GSASL_HAVE_SCRAM_SHA_256
- builtin_macro_create(US"_HAVE_AUTH_GSASL_SCRAM_SHA_256");
-# endif
-# ifdef EXIM_GSASL_SCRAM_S_KEY
- builtin_macro_create(US"_HAVE_AUTH_GSASL_SCRAM_S_KEY");
-# endif
-}
-
-#else /*!MACRO_PREDEF*/
-
-
-
-/* "Globals" for managing the gsasl interface. */
-
-static Gsasl *gsasl_ctx = NULL;
-static int
- main_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop);
-static int
- server_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock);
-static int
- client_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock);
-
-static BOOL sasl_error_should_defer = FALSE;
-static Gsasl_property callback_loop = 0;
-static BOOL checked_server_condition = FALSE;
-
-enum { CURRENTLY_SERVER = 1, CURRENTLY_CLIENT = 2 };
-
-struct callback_exim_state {
- auth_instance *ablock;
- int currently;
-};
-
-
-/*************************************************
-* Initialization entry point *
-*************************************************/
-
-/* Called for each instance, after its options have been read, to
-enable consistency checks to be done, or anything else that needs
-to be set up. */
-
-void
-auth_gsasl_init(auth_instance *ablock)
-{
-static char * once = NULL;
-int rc;
-auth_gsasl_options_block *ob =
- (auth_gsasl_options_block *)(ablock->options_block);
-
-/* As per existing Cyrus glue, use the authenticator's public name as
-the default for the mechanism name; we don't handle multiple mechanisms
-in one authenticator, but the same driver can be used multiple times. */
-
-if (!ob->server_mech)
- ob->server_mech = string_copy(ablock->public_name);
-
-/* Can get multiple session contexts from one library context, so just
-initialise the once. */
-
-if (!gsasl_ctx)
- {
- if ((rc = gsasl_init(&gsasl_ctx)) != GSASL_OK)
- log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: "
- "couldn't initialise GNU SASL library: %s (%s)",
- ablock->name, gsasl_strerror_name(rc), gsasl_strerror(rc));
-
- gsasl_callback_set(gsasl_ctx, main_callback);
- }
-
-/* We don't need this except to log it for debugging. */
-
-HDEBUG(D_auth) if (!once)
- {
- if ((rc = gsasl_server_mechlist(gsasl_ctx, &once)) != GSASL_OK)
- log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: "
- "failed to retrieve list of mechanisms: %s (%s)",
- ablock->name, gsasl_strerror_name(rc), gsasl_strerror(rc));
-
- debug_printf("GNU SASL supports: %s\n", once);
- }
-
-if (!gsasl_client_support_p(gsasl_ctx, CCS ob->server_mech))
- log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: "
- "GNU SASL does not support mechanism \"%s\"",
- ablock->name, ob->server_mech);
-
-if (ablock->server_condition)
- ablock->server = TRUE;
-else if( ob->server_mech
- && !STREQIC(ob->server_mech, US"EXTERNAL")
- && !STREQIC(ob->server_mech, US"ANONYMOUS")
- && !STREQIC(ob->server_mech, US"PLAIN")
- && !STREQIC(ob->server_mech, US"LOGIN")
- )
- {
- /* At present, for mechanisms we don't panic on absence of server_condition;
- need to figure out the most generically correct approach to deciding when
- it's critical and when it isn't. Eg, for simple validation (PLAIN mechanism,
- etc) it clearly is critical.
- */
-
- ablock->server = FALSE;
- HDEBUG(D_auth) debug_printf("%s authenticator: "
- "Need server_condition for %s mechanism\n",
- ablock->name, ob->server_mech);
- }
-
-/* This does *not* scale to new SASL mechanisms. Need a better way to ask
-which properties will be needed. */
-
-if ( !ob->server_realm
- && STREQIC(ob->server_mech, US"DIGEST-MD5"))
- {
- ablock->server = FALSE;
- HDEBUG(D_auth) debug_printf("%s authenticator: "
- "Need server_realm for %s mechanism\n",
- ablock->name, ob->server_mech);
- }
-
-ablock->client = ob->client_username && ob->client_password;
-}
-
-
-/* GNU SASL uses one top-level callback, registered at library level.
-We dispatch to client and server functions instead. */
-
-static int
-main_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop)
-{
-int rc = 0;
-struct callback_exim_state *cb_state =
- (struct callback_exim_state *)gsasl_session_hook_get(sctx);
-
-if (!cb_state)
- {
- HDEBUG(D_auth) debug_printf("gsasl callback (%d) not from our server/client processing\n", prop);
-#ifdef CHANNELBIND_HACK
- if (prop == GSASL_CB_TLS_UNIQUE)
- {
- uschar * s;
- if ((s = gsasl_callback_hook_get(ctx))) /* Gross hack for early lib vers */
- {
- HDEBUG(D_auth) debug_printf("GSASL_CB_TLS_UNIQUE from ctx hook\n");
- gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, CS s);
- }
- else
- {
- HDEBUG(D_auth) debug_printf("GSASL_CB_TLS_UNIQUE! dummy for now\n");
- gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, "");
- }
- return GSASL_OK;
- }
-#endif
- return GSASL_NO_CALLBACK;
- }
-
-HDEBUG(D_auth)
- debug_printf("GNU SASL Callback entered, prop=%d (loop prop=%d)\n",
- prop, callback_loop);
-
-if (callback_loop > 0)
- {
- /* Most likely is that we were asked for property FOO, and to
- expand the string we asked for property BAR to put into an auth
- variable, but property BAR is not supplied for this mechanism. */
- HDEBUG(D_auth)
- debug_printf("Loop, asked for property %d while handling property %d\n",
- prop, callback_loop);
- return GSASL_NO_CALLBACK;
- }
-callback_loop = prop;
-
-if (cb_state->currently == CURRENTLY_CLIENT)
- rc = client_callback(ctx, sctx, prop, cb_state->ablock);
-else if (cb_state->currently == CURRENTLY_SERVER)
- rc = server_callback(ctx, sctx, prop, cb_state->ablock);
-else
- log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: "
- "unhandled callback state, bug in Exim", cb_state->ablock->name);
- /* NOTREACHED */
-
-callback_loop = 0;
-return rc;
-}
-
-
-/*************************************************
-* Debug service function *
-*************************************************/
-static const uschar *
-gsasl_prop_code_to_name(Gsasl_property prop)
-{
-switch (prop)
- {
- case GSASL_AUTHID: return US"AUTHID";
- case GSASL_AUTHZID: return US"AUTHZID";
- case GSASL_PASSWORD: return US"PASSWORD";
- case GSASL_ANONYMOUS_TOKEN: return US"ANONYMOUS_TOKEN";
- case GSASL_SERVICE: return US"SERVICE";
- case GSASL_HOSTNAME: return US"HOSTNAME";
- case GSASL_GSSAPI_DISPLAY_NAME: return US"GSSAPI_DISPLAY_NAME";
- case GSASL_PASSCODE: return US"PASSCODE";
- case GSASL_SUGGESTED_PIN: return US"SUGGESTED_PIN";
- case GSASL_PIN: return US"PIN";
- case GSASL_REALM: return US"REALM";
- case GSASL_DIGEST_MD5_HASHED_PASSWORD: return US"DIGEST_MD5_HASHED_PASSWORD";
- case GSASL_QOPS: return US"QOPS";
- case GSASL_QOP: return US"QOP";
- case GSASL_SCRAM_ITER: return US"SCRAM_ITER";
- case GSASL_SCRAM_SALT: return US"SCRAM_SALT";
- case GSASL_SCRAM_SALTED_PASSWORD: return US"SCRAM_SALTED_PASSWORD";
-#ifdef EXIM_GSASL_SCRAM_S_KEY
- case GSASL_SCRAM_STOREDKEY: return US"SCRAM_STOREDKEY";
- case GSASL_SCRAM_SERVERKEY: return US"SCRAM_SERVERKEY";
-#endif
-#ifdef EXIM_GSASL_HAVE_EXPORTER /* v. 2.1.0 */
- case GSASL_CB_TLS_EXPORTER: return US"CB_TLS_EXPORTER";
-#endif
- case GSASL_CB_TLS_UNIQUE: return US"CB_TLS_UNIQUE";
- case GSASL_SAML20_IDP_IDENTIFIER: return US"SAML20_IDP_IDENTIFIER";
- case GSASL_SAML20_REDIRECT_URL: return US"SAML20_REDIRECT_URL";
- case GSASL_OPENID20_REDIRECT_URL: return US"OPENID20_REDIRECT_URL";
- case GSASL_OPENID20_OUTCOME_DATA: return US"OPENID20_OUTCOME_DATA";
- case GSASL_SAML20_AUTHENTICATE_IN_BROWSER: return US"SAML20_AUTHENTICATE_IN_BROWSER";
- case GSASL_OPENID20_AUTHENTICATE_IN_BROWSER: return US"OPENID20_AUTHENTICATE_IN_BROWSER";
- case GSASL_VALIDATE_SIMPLE: return US"VALIDATE_SIMPLE";
- case GSASL_VALIDATE_EXTERNAL: return US"VALIDATE_EXTERNAL";
- case GSASL_VALIDATE_ANONYMOUS: return US"VALIDATE_ANONYMOUS";
- case GSASL_VALIDATE_GSSAPI: return US"VALIDATE_GSSAPI";
- case GSASL_VALIDATE_SECURID: return US"VALIDATE_SECURID";
- case GSASL_VALIDATE_SAML20: return US"VALIDATE_SAML20";
- case GSASL_VALIDATE_OPENID20: return US"VALIDATE_OPENID20";
- }
-return CUS string_sprintf("(unknown prop: %d)", (int)prop);
-}
-
-static void
-preload_prop(Gsasl_session * sctx, Gsasl_property propcode, const uschar * val)
-{
-DEBUG(D_auth) debug_printf("preloading prop %s val %s\n",
- gsasl_prop_code_to_name(propcode), val);
-gsasl_property_set(sctx, propcode, CCS val);
-}
-
-/*************************************************
-* Server entry point *
-*************************************************/
-
-/* For interface, see auths/README */
-
-int
-auth_gsasl_server(auth_instance * ablock, uschar * initial_data)
-{
-uschar * tmps;
-char * to_send, * received;
-Gsasl_session * sctx = NULL;
-auth_gsasl_options_block * ob =
- (auth_gsasl_options_block *)(ablock->options_block);
-struct callback_exim_state cb_state;
-int rc, auth_result, exim_error, exim_error_override;
-
-HDEBUG(D_auth)
- debug_printf("GNU SASL: initialising session for %s, mechanism %s\n",
- ablock->name, ob->server_mech);
-
-#ifndef DISABLE_TLS
-if (tls_in.channelbinding && ob->server_channelbinding)
- {
-# ifndef DISABLE_TLS_RESUME
- if (!tls_in.ext_master_secret && tls_in.resumption == RESUME_USED)
- { /* per RFC 7677 section 4 */
- HDEBUG(D_auth) debug_printf(
- "channel binding not usable on resumed TLS without extended-master-secret");
- return FAIL;
- }
-# endif
-# ifdef CHANNELBIND_HACK
-/* This is a gross hack to get around the library before 1.9.2
-a) requiring that c-b was already set, at the _start() call, and
-b) caching a b64'd version of the binding then which it never updates. */
-
- gsasl_callback_hook_set(gsasl_ctx, tls_in.channelbinding);
-# endif
- }
-#endif
-
-if ((rc = gsasl_server_start(gsasl_ctx, CCS ob->server_mech, &sctx)) != GSASL_OK)
- {
- auth_defer_msg = string_sprintf("GNU SASL: session start failure: %s (%s)",
- gsasl_strerror_name(rc), gsasl_strerror(rc));
- HDEBUG(D_auth) debug_printf("%s\n", auth_defer_msg);
- return DEFER;
- }
-/* Hereafter: gsasl_finish(sctx) please */
-
-cb_state.ablock = ablock;
-cb_state.currently = CURRENTLY_SERVER;
-gsasl_session_hook_set(sctx, &cb_state);
-
-tmps = expand_string(ob->server_service);
-preload_prop(sctx, GSASL_SERVICE, tmps);
-tmps = expand_string(ob->server_hostname);
-preload_prop(sctx, GSASL_HOSTNAME, tmps);
-if (ob->server_realm)
- {
- tmps = expand_string(ob->server_realm);
- if (tmps && *tmps)
- preload_prop(sctx, GSASL_REALM, tmps);
- }
-/* We don't support protection layers. */
-preload_prop(sctx, GSASL_QOPS, US "qop-auth");
-
-#ifndef DISABLE_TLS
-if (tls_in.channelbinding)
- {
- /* Some auth mechanisms can ensure that both sides are talking withing the
- same security context; for TLS, this means that even if a bad certificate
- has been accepted, they remain MitM-proof because both sides must be within
- the same negotiated session; if someone is terminating one session and
- proxying data on within a second, authentication will fail.
-
- We might not have this available, depending upon TLS implementation,
- ciphersuite, phase of moon ...
-
- If we do, it results in extra SASL mechanisms being available; here,
- Exim's one-mechanism-per-authenticator potentially causes problems.
- It depends upon how GNU SASL will implement the PLUS variants of GS2
- and whether it automatically mandates a switch to the bound PLUS
- if the data is available. Since default-on, despite being more secure,
- would then result in mechanism name changes on a library update, we
- have little choice but to default it off and let the admin choose to
- enable it. *sigh*
-
- Earlier library versions need this set early, during the _start() call,
- so we had to misuse gsasl_callback_hook_set/get() as a data transfer
- mech for the callback done at that time to get the bind-data. More recently
- the callback is done (if needed) during the first gsasl_stop(). We know
- the bind-data here so can set it (and should not get a callback).
- */
- if (ob->server_channelbinding)
- {
- HDEBUG(D_auth) debug_printf("Auth %s: Enabling channel-binding\n",
- ablock->name);
-# ifndef CHANNELBIND_HACK
- preload_prop(sctx,
-# ifdef EXIM_GSASL_HAVE_EXPORTER
- tls_in.channelbind_exporter ? GSASL_CB_TLS_EXPORTER :
-# endif
- GSASL_CB_TLS_UNIQUE,
- tls_in.channelbinding);
-# endif
- }
- else
- HDEBUG(D_auth)
- debug_printf("Auth %s: Not enabling channel-binding (data available)\n",
- ablock->name);
- }
-else
- HDEBUG(D_auth)
- debug_printf("Auth %s: no channel-binding data available\n",
- ablock->name);
-#endif
-
-checked_server_condition = FALSE;
-
-received = CS initial_data;
-to_send = NULL;
-exim_error = exim_error_override = OK;
-
-do {
- switch (rc = gsasl_step64(sctx, received, &to_send))
- {
- case GSASL_OK:
- if (!to_send)
- goto STOP_INTERACTION;
- break;
-
- case GSASL_NEEDS_MORE:
- break;
-
- case GSASL_AUTHENTICATION_ERROR:
- case GSASL_INTEGRITY_ERROR:
- case GSASL_NO_AUTHID:
- case GSASL_NO_ANONYMOUS_TOKEN:
- case GSASL_NO_AUTHZID:
- case GSASL_NO_PASSWORD:
- case GSASL_NO_PASSCODE:
- case GSASL_NO_PIN:
- case GSASL_BASE64_ERROR:
- HDEBUG(D_auth) debug_printf("GNU SASL permanent error: %s (%s)\n",
- gsasl_strerror_name(rc), gsasl_strerror(rc));
- log_write(0, LOG_REJECT, "%s authenticator (%s):\n "
- "GNU SASL permanent failure: %s (%s)",
- ablock->name, ob->server_mech,
- gsasl_strerror_name(rc), gsasl_strerror(rc));
- if (rc == GSASL_BASE64_ERROR)
- exim_error_override = BAD64;
- goto STOP_INTERACTION;
-
- default:
- auth_defer_msg = string_sprintf("GNU SASL temporary error: %s (%s)",
- gsasl_strerror_name(rc), gsasl_strerror(rc));
- HDEBUG(D_auth) debug_printf("%s\n", auth_defer_msg);
- exim_error_override = DEFER;
- goto STOP_INTERACTION;
- }
-
- /*XXX having our caller send the final smtp "235" is unfortunate; wastes a roundtrip */
- if ((rc == GSASL_NEEDS_MORE) || (to_send && *to_send))
- exim_error = auth_get_no64_data(USS &received, US to_send);
-
- if (to_send)
- {
- free(to_send);
- to_send = NULL;
- }
-
- if (exim_error)
- break; /* handles * cancelled check */
-
- } while (rc == GSASL_NEEDS_MORE);
-
-STOP_INTERACTION:
-auth_result = rc;
-
-HDEBUG(D_auth)
- {
- const uschar * s;
- if ((s = CUS gsasl_property_fast(sctx, GSASL_SCRAM_ITER)))
- debug_printf(" - itercnt: '%s'\n", s);
- if ((s = CUS gsasl_property_fast(sctx, GSASL_SCRAM_SALT)))
- debug_printf(" - salt: '%s'\n", s);
-#ifdef EXIM_GSASL_SCRAM_S_KEY
- if ((s = CUS gsasl_property_fast(sctx, GSASL_SCRAM_SERVERKEY)))
- debug_printf(" - ServerKey: '%s'\n", s);
- if ((s = CUS gsasl_property_fast(sctx, GSASL_SCRAM_STOREDKEY)))
- debug_printf(" - StoredKey: '%s'\n", s);
-#endif
- }
-
-gsasl_finish(sctx);
-
-/* Can return: OK DEFER FAIL CANCELLED BAD64 UNEXPECTED */
-
-if (exim_error != OK)
- return exim_error;
-
-if (auth_result != GSASL_OK)
- {
- HDEBUG(D_auth) debug_printf("authentication returned %s (%s)\n",
- gsasl_strerror_name(auth_result), gsasl_strerror(auth_result));
- if (exim_error_override != OK)
- return exim_error_override; /* might be DEFER */
- if (sasl_error_should_defer) /* overriding auth failure SASL error */
- return DEFER;
- return FAIL;
- }
-
-/* Auth succeeded, check server_condition unless already done in callback */
-return checked_server_condition ? OK : auth_check_serv_cond(ablock);
-}
-
-
-/* returns the GSASL status of expanding the Exim string given */
-static int
-condition_check(auth_instance *ablock, uschar *label, uschar *condition_string)
-{
-int exim_rc = auth_check_some_cond(ablock, label, condition_string, FAIL);
-switch (exim_rc)
- {
- case OK: return GSASL_OK;
- case DEFER: sasl_error_should_defer = TRUE;
- return GSASL_AUTHENTICATION_ERROR;
- case FAIL: return GSASL_AUTHENTICATION_ERROR;
- default: log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: "
- "Unhandled return from checking %s: %d",
- ablock->name, label, exim_rc);
- }
-
-/* NOTREACHED */
-return GSASL_AUTHENTICATION_ERROR;
-}
-
-
-/* Set the "next" $auth[n] and increment expand_nmax */
-
-static void
-set_exim_authvar_from_prop(Gsasl_session * sctx, Gsasl_property prop)
-{
-uschar * propval = US gsasl_property_fast(sctx, prop);
-int i = expand_nmax, j = i + 1;
-propval = propval ? string_copy(propval) : US"";
-HDEBUG(D_auth) debug_printf("auth[%d] <= %s'%s'\n",
- j, gsasl_prop_code_to_name(prop), propval);
-expand_nstring[j] = propval;
-expand_nlength[j] = Ustrlen(propval);
-if (i < AUTH_VARS) auth_vars[i] = propval;
-expand_nmax = j;
-}
-
-static void
-set_exim_authvars_from_a_az_r_props(Gsasl_session * sctx)
-{
-if (expand_nmax > 0 ) return;
-
-/* Asking for GSASL_AUTHZID calls back into us if we use
-gsasl_property_get(), thus the use of gsasl_property_fast().
-Do we really want to hardcode limits per mechanism? What happens when
-a new mechanism is added to the library. It *shouldn't* result in us
-needing to add more glue, since avoiding that is a large part of the
-point of SASL. */
-
-set_exim_authvar_from_prop(sctx, GSASL_AUTHID);
-set_exim_authvar_from_prop(sctx, GSASL_AUTHZID);
-set_exim_authvar_from_prop(sctx, GSASL_REALM);
-}
-
-
-static int
-prop_from_option(Gsasl_session * sctx, Gsasl_property prop,
- const uschar * option)
-{
-HDEBUG(D_auth) debug_printf(" %s\n", gsasl_prop_code_to_name(prop));
-if (option)
- {
- set_exim_authvars_from_a_az_r_props(sctx);
- option = expand_cstring(option);
- HDEBUG(D_auth) debug_printf(" '%s'\n", option);
- if (*option)
- gsasl_property_set(sctx, prop, CCS option);
- return GSASL_OK;
- }
-HDEBUG(D_auth) debug_printf(" option not set\n");
-return GSASL_NO_CALLBACK;
-}
-
-static int
-server_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop,
- auth_instance *ablock)
-{
-char * tmps;
-uschar * s;
-int cbrc = GSASL_NO_CALLBACK;
-auth_gsasl_options_block * ob =
- (auth_gsasl_options_block *)(ablock->options_block);
-
-HDEBUG(D_auth) debug_printf("GNU SASL callback %s for %s/%s as server\n",
- gsasl_prop_code_to_name(prop), ablock->name, ablock->public_name);
-
-for (int i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL;
-expand_nmax = 0;
-
-switch (prop)
- {
- case GSASL_VALIDATE_SIMPLE:
- /* GSASL_AUTHID, GSASL_AUTHZID, and GSASL_PASSWORD */
- set_exim_authvar_from_prop(sctx, GSASL_AUTHID);
- set_exim_authvar_from_prop(sctx, GSASL_AUTHZID);
- set_exim_authvar_from_prop(sctx, GSASL_PASSWORD);
-
- cbrc = condition_check(ablock, US"server_condition", ablock->server_condition);
- checked_server_condition = TRUE;
- break;
-
- case GSASL_VALIDATE_EXTERNAL:
- if (!ablock->server_condition)
- {
- HDEBUG(D_auth) debug_printf("No server_condition supplied, to validate EXTERNAL\n");
- cbrc = GSASL_AUTHENTICATION_ERROR;
- break;
- }
- set_exim_authvar_from_prop(sctx, GSASL_AUTHZID);
-
- cbrc = condition_check(ablock,
- US"server_condition (EXTERNAL)", ablock->server_condition);
- checked_server_condition = TRUE;
- break;
-
- case GSASL_VALIDATE_ANONYMOUS:
- if (!ablock->server_condition)
- {
- HDEBUG(D_auth) debug_printf("No server_condition supplied, to validate ANONYMOUS\n");
- cbrc = GSASL_AUTHENTICATION_ERROR;
- break;
- }
- set_exim_authvar_from_prop(sctx, GSASL_ANONYMOUS_TOKEN);
-
- cbrc = condition_check(ablock,
- US"server_condition (ANONYMOUS)", ablock->server_condition);
- checked_server_condition = TRUE;
- break;
-
- case GSASL_VALIDATE_GSSAPI:
- /* GSASL_AUTHZID and GSASL_GSSAPI_DISPLAY_NAME
- The display-name is authenticated as part of GSS, the authzid is claimed
- by the SASL integration after authentication; protected against tampering
- (if the SASL mechanism supports that, which Kerberos does) but is
- unverified, same as normal for other mechanisms.
- First coding, we had these values swapped, but for consistency and prior
- to the first release of Exim with this authenticator, they've been
- switched to match the ordering of GSASL_VALIDATE_SIMPLE. */
-
- set_exim_authvar_from_prop(sctx, GSASL_GSSAPI_DISPLAY_NAME);
- set_exim_authvar_from_prop(sctx, GSASL_AUTHZID);
-
- /* In this one case, it perhaps makes sense to default back open?
- But for consistency, let's just mandate server_condition here too. */
-
- cbrc = condition_check(ablock,
- US"server_condition (GSSAPI family)", ablock->server_condition);
- checked_server_condition = TRUE;
- break;
-
- case GSASL_SCRAM_ITER:
- cbrc = prop_from_option(sctx, prop, ob->server_scram_iter);
- break;
-
- case GSASL_SCRAM_SALT:
- cbrc = prop_from_option(sctx, prop, ob->server_scram_salt);
- break;
-
-#ifdef EXIM_GSASL_SCRAM_S_KEY
- case GSASL_SCRAM_STOREDKEY:
- cbrc = prop_from_option(sctx, prop, ob->server_s_key);
- break;
-
- case GSASL_SCRAM_SERVERKEY:
- cbrc = prop_from_option(sctx, prop, ob->server_key);
- break;
-#endif
-
- case GSASL_PASSWORD:
- /* SCRAM-*: GSASL_AUTHID, GSASL_AUTHZID and GSASL_REALM
- DIGEST-MD5: GSASL_AUTHID, GSASL_AUTHZID and GSASL_REALM
- CRAM-MD5: GSASL_AUTHID
- PLAIN: GSASL_AUTHID and GSASL_AUTHZID
- LOGIN: GSASL_AUTHID
- */
- set_exim_authvars_from_a_az_r_props(sctx);
-
- if (!(s = ob->server_password))
- {
- HDEBUG(D_auth) debug_printf("option not set\n");
- break;
- }
- if (!(tmps = CS expand_string(s)))
- {
- sasl_error_should_defer = !f.expand_string_forcedfail;
- HDEBUG(D_auth) debug_printf("server_password expansion failed, so "
- "can't tell GNU SASL library the password for %s\n", auth_vars[0]);
- return GSASL_AUTHENTICATION_ERROR;
- }
- HDEBUG(D_auth) debug_printf(" set\n");
- gsasl_property_set(sctx, GSASL_PASSWORD, tmps);
-
- /* This is inadequate; don't think Exim's store stacks are geared
- for memory wiping, so expanding strings will leave stuff laying around.
- But no need to compound the problem, so get rid of the one we can. */
-
- if (US tmps != s) memset(tmps, '\0', strlen(tmps));
- cbrc = GSASL_OK;
- break;
-
- default:
- HDEBUG(D_auth) debug_printf(" Unrecognised callback: %d\n", prop);
- cbrc = GSASL_NO_CALLBACK;
- }
-
-HDEBUG(D_auth) debug_printf("Returning %s (%s)\n",
- gsasl_strerror_name(cbrc), gsasl_strerror(cbrc));
-
-return cbrc;
-}
-
-
-/******************************************************************************/
-
-#define PROP_OPTIONAL BIT(0)
-
-static BOOL
-set_client_prop(Gsasl_session * sctx, Gsasl_property prop, uschar * val,
- unsigned flags, uschar * buffer, int buffsize)
-{
-uschar * s;
-
-if (!val) return !!(flags & PROP_OPTIONAL);
-if (!(s = expand_string(val)) || !(flags & PROP_OPTIONAL) && !*s)
- {
- string_format(buffer, buffsize, "%s", expand_string_message);
- return FALSE;
- }
-if (*s)
- {
- HDEBUG(D_auth) debug_printf("%s: set %s = '%s'\n", __FUNCTION__,
- gsasl_prop_code_to_name(prop), s);
- gsasl_property_set(sctx, prop, CS s);
- }
-
-return TRUE;
-}
-
-/*************************************************
-* Client entry point *
-*************************************************/
-
-/* For interface, see auths/README */
-
-int
-auth_gsasl_client(
- auth_instance * ablock, /* authenticator block */
- void * sx, /* connection */
- int timeout, /* command timeout */
- uschar * buffer, /* buffer for reading response */
- int buffsize) /* size of buffer */
-{
-auth_gsasl_options_block * ob =
- (auth_gsasl_options_block *)(ablock->options_block);
-Gsasl_session * sctx = NULL;
-struct callback_exim_state cb_state;
-uschar * s;
-BOOL initial = TRUE;
-int rc, yield = FAIL;
-
-HDEBUG(D_auth)
- debug_printf("GNU SASL: initialising session for %s, mechanism %s\n",
- ablock->name, ob->server_mech);
-
-*buffer = 0;
-
-#ifndef DISABLE_TLS
-if (tls_out.channelbinding && ob->client_channelbinding)
- {
-# ifndef DISABLE_TLS_RESUME
- if (!tls_out.ext_master_secret && tls_out.resumption == RESUME_USED)
- { /* Per RFC 7677 section 4. See also RFC 7627, "Triple Handshake"
- vulnerability, and https://www.mitls.org/pages/attacks/3SHAKE */
- string_format(buffer, buffsize, "%s",
- "channel binding not usable on resumed TLS without extended-master-secret");
- return FAIL;
- }
-# endif
-# ifdef CHANNELBIND_HACK
- /* This is a gross hack to get around the library before 1.9.2
- a) requiring that c-b was already set, at the _start() call, and
- b) caching a b64'd version of the binding then which it never updates. */
-
- gsasl_callback_hook_set(gsasl_ctx, tls_out.channelbinding);
-# endif
- }
-#endif
-
-if ((rc = gsasl_client_start(gsasl_ctx, CCS ob->server_mech, &sctx)) != GSASL_OK)
- {
- string_format(buffer, buffsize, "GNU SASL: session start failure: %s (%s)",
- gsasl_strerror_name(rc), gsasl_strerror(rc));
- HDEBUG(D_auth) debug_printf("%s\n", buffer);
- return ERROR;
- }
-
-cb_state.ablock = ablock;
-cb_state.currently = CURRENTLY_CLIENT;
-gsasl_session_hook_set(sctx, &cb_state);
-
-/* Set properties */
-
-if ( !set_client_prop(sctx, GSASL_PASSWORD, ob->client_password,
- 0, buffer, buffsize)
- || !set_client_prop(sctx, GSASL_AUTHID, ob->client_username,
- 0, buffer, buffsize)
- || !set_client_prop(sctx, GSASL_AUTHZID, ob->client_authz,
- PROP_OPTIONAL, buffer, buffsize)
- )
- return ERROR;
-
-#ifndef DISABLE_TLS
-if (tls_out.channelbinding)
- if (ob->client_channelbinding)
- {
- HDEBUG(D_auth) debug_printf("Auth %s: Enabling channel-binding\n",
- ablock->name);
-# ifndef CHANNELBIND_HACK
- preload_prop(sctx,
-# ifdef EXIM_GSASL_HAVE_EXPORTER
- tls_out.channelbind_exporter ? GSASL_CB_TLS_EXPORTER :
-# endif
- GSASL_CB_TLS_UNIQUE,
- tls_out.channelbinding);
-# endif
- }
- else
- HDEBUG(D_auth)
- debug_printf("Auth %s: Not enabling channel-binding (data available)\n",
- ablock->name);
-#endif
-
-/* Run the SASL conversation with the server */
-
-for(s = NULL; ;)
- {
- uschar * outstr;
- BOOL fail = TRUE;
-
- rc = gsasl_step64(sctx, CS s, CSS &outstr);
-
- if (rc == GSASL_NEEDS_MORE || rc == GSASL_OK)
- {
- fail = initial
- ? smtp_write_command(sx, SCMD_FLUSH,
- outstr ? "AUTH %s %s\r\n" : "AUTH %s\r\n",
- ablock->public_name, outstr) <= 0
- : outstr
- ? smtp_write_command(sx, SCMD_FLUSH, "%s\r\n", outstr) <= 0
- : FALSE;
- free(outstr);
- if (fail)
- {
- yield = FAIL_SEND;
- goto done;
- }
- initial = FALSE;
- }
-
- if (rc != GSASL_NEEDS_MORE)
- {
- if (rc != GSASL_OK)
- {
- string_format(buffer, buffsize, "gsasl: %s", gsasl_strerror(rc));
- break;
- }
-
- /* expecting a final 2xx from the server, accepting the AUTH */
-
- if (smtp_read_response(sx, buffer, buffsize, '2', timeout))
- yield = OK;
- break; /* from SASL sequence loop */
- }
-
- /* 2xx or 3xx response is acceptable. If 2xx, no further input */
-
- if (!smtp_read_response(sx, buffer, buffsize, '3', timeout))
- if (errno == 0 && buffer[0] == '2')
- buffer[4] = '\0';
- else
- {
- yield = FAIL;
- goto done;
- }
- s = buffer + 4;
- }
-
-done:
-if (yield == OK)
- {
- expand_nmax = 0;
- set_exim_authvar_from_prop(sctx, GSASL_AUTHID);
- set_exim_authvar_from_prop(sctx, GSASL_SCRAM_ITER);
- set_exim_authvar_from_prop(sctx, GSASL_SCRAM_SALT);
- set_exim_authvar_from_prop(sctx, GSASL_SCRAM_SALTED_PASSWORD);
- }
-
-gsasl_finish(sctx);
-return yield;
-}
-
-static int
-client_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock)
-{
-HDEBUG(D_auth) debug_printf("GNU SASL callback %s for %s/%s as client\n",
- gsasl_prop_code_to_name(prop), ablock->name, ablock->public_name);
-switch (prop)
- {
-#ifdef EXIM_GSASL_HAVE_EXPORTER
- case GSASL_CB_TLS_EXPORTER: /* Should never get called for this, as pre-set */
- if (!tls_out.channelbind_exporter) break;
- HDEBUG(D_auth) debug_printf(" filling in\n");
- gsasl_property_set(sctx, GSASL_CB_TLS_EXPORTER, CCS tls_out.channelbinding);
- return GSASL_OK;
-#endif
- case GSASL_CB_TLS_UNIQUE: /* Should never get called for this, as pre-set */
-#ifdef EXIM_GSASL_HAVE_EXPORTER
- if (tls_out.channelbind_exporter) break;
-#endif
- HDEBUG(D_auth) debug_printf(" filling in\n");
- gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, CCS tls_out.channelbinding);
- return GSASL_OK;
- case GSASL_SCRAM_SALTED_PASSWORD:
- {
- uschar * client_spassword =
- ((auth_gsasl_options_block *) ablock->options_block)->client_spassword;
- uschar dummy[4];
- HDEBUG(D_auth) if (!client_spassword)
- debug_printf(" client_spassword option unset\n");
- if (client_spassword)
- {
- expand_nmax = 0;
- set_exim_authvar_from_prop(sctx, GSASL_AUTHID);
- set_exim_authvar_from_prop(sctx, GSASL_SCRAM_ITER);
- set_exim_authvar_from_prop(sctx, GSASL_SCRAM_SALT);
- set_client_prop(sctx, GSASL_SCRAM_SALTED_PASSWORD, client_spassword,
- 0, dummy, sizeof(dummy));
- for (int i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL;
- expand_nmax = 0;
- }
- break;
- }
- default:
- HDEBUG(D_auth)
- debug_printf(" not providing one\n");
- break;
- }
-return GSASL_NO_CALLBACK;
-}
-
-/*************************************************
-* Diagnostic API *
-*************************************************/
-
-gstring *
-auth_gsasl_version_report(gstring * g)
-{
-return string_fmt_append(g, "Library version: GNU SASL: Compile: %s\n"
- " Runtime: %s\n",
- GSASL_VERSION, gsasl_check_version(NULL));
-}
-
-
-
-/* Dummy */
-void auth_gsasl_macros(void) {}
-
-#endif /*!MACRO_PREDEF*/
-#endif /* AUTH_GSASL */
-
-/* End of gsasl_exim.c */
git://git.exim.org / exim.git / blobdiff