* Exim - an Internet mail transport agent *
*************************************************/
+/* Copyright (c) The Exim Maintainers 2019 */
/* Copyright (c) University of Cambridge 1995 - 2018 */
/* See the file NOTICE for conditions of use and distribution. */
*/
#include "../exim.h"
+#define CHANNELBIND_HACK
#ifndef AUTH_GSASL
/* dummy function to satisfy compilers when we link in an "empty" file. */
#include <gsasl.h>
#include "gsasl_exim.h"
+#ifdef SUPPORT_I18N
+# include <stringprep.h>
+#endif
+
+
/* 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. */
optionlist auth_gsasl_options[] = {
+ { "client_authz", opt_stringptr,
+ (void *)(offsetof(auth_gsasl_options_block, client_authz)) },
+ { "client_channelbinding", opt_bool,
+ (void *)(offsetof(auth_gsasl_options_block, client_channelbinding)) },
+ { "client_password", opt_stringptr,
+ (void *)(offsetof(auth_gsasl_options_block, client_password)) },
+ { "client_username", opt_stringptr,
+ (void *)(offsetof(auth_gsasl_options_block, client_username)) },
+
{ "server_channelbinding", opt_bool,
(void *)(offsetof(auth_gsasl_options_block, server_channelbinding)) },
{ "server_hostname", opt_stringptr,
/* Defaults for the authenticator-specific options. */
auth_gsasl_options_block auth_gsasl_option_defaults = {
- US"smtp", /* server_service */
- US"$primary_hostname", /* server_hostname */
- NULL, /* server_realm */
- NULL, /* server_mech */
- NULL, /* server_password */
- NULL, /* server_scram_iter */
- NULL, /* server_scram_salt */
- FALSE /* server_channelbinding */
+ .server_service = US"smtp",
+ .server_hostname = US"$primary_hostname",
+ .server_scram_iter = US"4096",
+ /* all others zero/null */
};
void
auth_gsasl_init(auth_instance *ablock)
{
-char *p;
-int rc, supported;
+static char * once = NULL;
+int rc;
auth_gsasl_options_block *ob =
(auth_gsasl_options_block *)(ablock->options_block);
/* We don't need this except to log it for debugging. */
-if ((rc = gsasl_server_mechlist(gsasl_ctx, &p)) != 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));
+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));
-HDEBUG(D_auth) debug_printf("GNU SASL supports: %s\n", p);
+ debug_printf("GNU SASL supports: %s\n", once);
+ }
-supported = gsasl_client_support_p(gsasl_ctx, CCS ob->server_mech);
-if (!supported)
+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);
+ablock->server = TRUE;
+
if ( !ablock->server_condition
&& ( streqic(ob->server_mech, US"EXTERNAL")
|| streqic(ob->server_mech, US"ANONYMOUS")
|| streqic(ob->server_mech, US"PLAIN")
|| streqic(ob->server_mech, US"LOGIN")
) )
- log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: "
- "Need server_condition for %s mechanism",
+ {
+ 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"))
- log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: "
- "Need server_realm for %s mechanism",
+ {
+ ablock->server = FALSE;
+ HDEBUG(D_auth) debug_printf("%s authenticator: "
+ "Need server_realm for %s mechanism\n",
ablock->name, ob->server_mech);
+ }
/* 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.
-
-So don't activate without server_condition, this might be relaxed in the future.
*/
-if (ablock->server_condition) ablock->server = TRUE;
-ablock->client = FALSE;
+ablock->client = ob->client_username && ob->client_password;
}
struct callback_exim_state *cb_state =
(struct callback_exim_state *)gsasl_session_hook_get(sctx);
-HDEBUG(D_auth)
- debug_printf("GNU SASL Callback entered, prop=%d (loop prop=%d)\n",
- prop, callback_loop);
-
if (!cb_state)
{
- HDEBUG(D_auth) debug_printf(" not from our server/client processing.\n");
+ 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)))
+ {
+ 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. */
+ /* 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);
int rc, auth_result, exim_error, exim_error_override;
HDEBUG(D_auth)
- debug_printf("GNU SASL: initialising session for %s, mechanism %s.\n",
+ debug_printf("GNU SASL: initialising session for %s, mechanism %s\n",
ablock->name, ob->server_mech);
+#ifndef DISABLE_TLS
+# ifdef CHANNELBIND_HACK
+/* This is a gross hack to get around the library 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. */
+
+if (tls_in.channelbinding && ob->server_channelbinding)
+ 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)",
}
/* Hereafter: gsasl_finish(sctx) please */
-gsasl_session_hook_set(sctx, (void *)ablock);
cb_state.ablock = ablock;
cb_state.currently = CURRENTLY_SERVER;
-gsasl_session_hook_set(sctx, (void *)&cb_state);
+gsasl_session_hook_set(sctx, &cb_state);
tmps = CS expand_string(ob->server_service);
gsasl_property_set(sctx, GSASL_SERVICE, tmps);
{
HDEBUG(D_auth) debug_printf("Auth %s: Enabling channel-binding\n",
ablock->name);
- gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE,
- CCS tls_in.channelbinding);
+# ifdef CHANNELBIND_HACK
+ gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, CCS tls_in.channelbinding);
+# endif
}
else
HDEBUG(D_auth)
}
if ((rc == GSASL_NEEDS_MORE) || (to_send && *to_send))
- exim_error = auth_get_no64_data((uschar **)&received, US to_send);
+ exim_error = auth_get_no64_data(USS &received, US to_send);
if (to_send)
{
switch (prop)
{
case GSASL_VALIDATE_SIMPLE:
+ HDEBUG(D_auth) debug_printf(" VALIDATE_SIMPLE\n");
/* GSASL_AUTHID, GSASL_AUTHZID, and GSASL_PASSWORD */
- propval = US gsasl_property_fast(sctx, GSASL_AUTHID);
+ propval = US gsasl_property_fast(sctx, GSASL_AUTHID);
auth_vars[0] = expand_nstring[1] = propval ? string_copy(propval) : US"";
- propval = US gsasl_property_fast(sctx, GSASL_AUTHZID);
+ propval = US gsasl_property_fast(sctx, GSASL_AUTHZID);
auth_vars[1] = expand_nstring[2] = propval ? string_copy(propval) : US"";
- propval = US gsasl_property_fast(sctx, GSASL_PASSWORD);
+ propval = US gsasl_property_fast(sctx, GSASL_PASSWORD);
auth_vars[2] = expand_nstring[3] = propval ? string_copy(propval) : US"";
expand_nmax = 3;
for (int i = 1; i <= 3; ++i)
break;
case GSASL_VALIDATE_EXTERNAL:
+ HDEBUG(D_auth) debug_printf(" VALIDATE_EXTERNAL\n");
if (!ablock->server_condition)
{
- HDEBUG(D_auth) debug_printf("No server_condition supplied, to validate EXTERNAL.\n");
+ HDEBUG(D_auth) debug_printf("No server_condition supplied, to validate EXTERNAL\n");
cbrc = GSASL_AUTHENTICATION_ERROR;
break;
}
- propval = US gsasl_property_fast(sctx, GSASL_AUTHZID);
+ propval = US gsasl_property_fast(sctx, GSASL_AUTHZID);
/* We always set $auth1, even if only to empty string. */
auth_vars[0] = expand_nstring[1] = propval ? string_copy(propval) : US"";
break;
case GSASL_VALIDATE_ANONYMOUS:
+ HDEBUG(D_auth) debug_printf(" VALIDATE_ANONYMOUS\n");
if (!ablock->server_condition)
{
- HDEBUG(D_auth) debug_printf("No server_condition supplied, to validate ANONYMOUS.\n");
+ HDEBUG(D_auth) debug_printf("No server_condition supplied, to validate ANONYMOUS\n");
cbrc = GSASL_AUTHENTICATION_ERROR;
break;
}
- propval = US gsasl_property_fast(sctx, GSASL_ANONYMOUS_TOKEN);
+ propval = US gsasl_property_fast(sctx, GSASL_ANONYMOUS_TOKEN);
/* We always set $auth1, even if only to empty string. */
break;
case GSASL_VALIDATE_GSSAPI:
+ HDEBUG(D_auth) debug_printf(" VALIDATE_GSSAPI\n");
/* 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
to the first release of Exim with this authenticator, they've been
switched to match the ordering of GSASL_VALIDATE_SIMPLE. */
- propval = US gsasl_property_fast(sctx, GSASL_GSSAPI_DISPLAY_NAME);
+ propval = US gsasl_property_fast(sctx, GSASL_GSSAPI_DISPLAY_NAME);
auth_vars[0] = expand_nstring[1] = propval ? string_copy(propval) : US"";
- propval = US gsasl_property_fast(sctx, GSASL_AUTHZID);
+ propval = US gsasl_property_fast(sctx, GSASL_AUTHZID);
auth_vars[1] = expand_nstring[2] = propval ? string_copy(propval) : US"";
expand_nmax = 2;
for (int i = 1; i <= 2; ++i)
break;
case GSASL_SCRAM_ITER:
+ HDEBUG(D_auth) debug_printf(" SCRAM_ITER\n");
if (ob->server_scram_iter)
{
tmps = CS expand_string(ob->server_scram_iter);
break;
case GSASL_SCRAM_SALT:
+ HDEBUG(D_auth) debug_printf(" SCRAM_SALT\n");
if (ob->server_scram_iter)
{
tmps = CS expand_string(ob->server_scram_salt);
break;
case GSASL_PASSWORD:
+ HDEBUG(D_auth) debug_printf(" PASSWORD\n");
/* DIGEST-MD5: GSASL_AUTHID, GSASL_AUTHZID and GSASL_REALM
CRAM-MD5: GSASL_AUTHID
PLAIN: GSASL_AUTHID and GSASL_AUTHZID
needing to add more glue, since avoiding that is a large part of the
point of SASL. */
- propval = US gsasl_property_fast(sctx, GSASL_AUTHID);
+ propval = US gsasl_property_fast(sctx, GSASL_AUTHID);
auth_vars[0] = expand_nstring[1] = propval ? string_copy(propval) : US"";
- propval = US gsasl_property_fast(sctx, GSASL_AUTHZID);
+ propval = US gsasl_property_fast(sctx, GSASL_AUTHZID);
auth_vars[1] = expand_nstring[2] = propval ? string_copy(propval) : US"";
- propval = US gsasl_property_fast(sctx, GSASL_REALM);
+ propval = US gsasl_property_fast(sctx, GSASL_REALM);
auth_vars[2] = expand_nstring[3] = propval ? string_copy(propval) : US"";
expand_nmax = 3;
for (int i = 1; i <= 3; ++i)
break;
default:
- HDEBUG(D_auth) debug_printf("Unrecognised callback: %d\n", prop);
+ HDEBUG(D_auth) debug_printf(" Unrecognised callback: %d\n", prop);
cbrc = GSASL_NO_CALLBACK;
}
}
+/******************************************************************************/
+
+#define PROP_OPTIONAL BIT(0)
+#define PROP_STRINGPREP BIT(1)
+
+
+static BOOL
+client_prop(Gsasl_session * sctx, Gsasl_property propnum, uschar * val,
+ const uschar * why, unsigned flags, uschar * buffer, int buffsize)
+{
+uschar * s, * t;
+int rc;
+
+if (flags & PROP_OPTIONAL && !val) return TRUE;
+if (!(s = expand_string(val)) || !(flags & PROP_OPTIONAL) && !*s)
+ {
+ string_format(buffer, buffsize, "%s", expand_string_message);
+ return FALSE;
+ }
+if (!*s) return TRUE;
+
+#ifdef SUPPORT_I18N
+if (flags & PROP_STRINGPREP)
+ {
+ if (gsasl_saslprep(CCS s, 0, CSS &t, &rc) != GSASL_OK)
+ {
+ string_format(buffer, buffsize, "Bad result from saslprep(%s): %s\n",
+ why, stringprep_strerror(rc));
+ HDEBUG(D_auth) debug_printf("%s\n", buffer);
+ return FALSE;
+ }
+ gsasl_property_set(sctx, propnum, CS t);
+
+ free(t);
+ }
+else
+#endif
+ gsasl_property_set(sctx, propnum, CS s);
+
+return TRUE;
+}
+
/*************************************************
* Client entry point *
*************************************************/
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, do_stringprep;
+int rc, yield = FAIL, flags;
+
HDEBUG(D_auth)
- debug_printf("Client side NOT IMPLEMENTED: you should not see this!\n");
-/* NOT IMPLEMENTED */
-return FAIL;
+ debug_printf("GNU SASL: initialising session for %s, mechanism %s\n",
+ ablock->name, ob->server_mech);
+
+*buffer = 0;
+
+#ifndef DISABLE_TLS
+/* This is a gross hack to get around the library 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. */
+
+if (tls_out.channelbinding)
+ if (ob->client_channelbinding)
+ gsasl_callback_hook_set(gsasl_ctx, tls_out.channelbinding);
+#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 */
+
+flags = Ustrncmp(ob->server_mech, "SCRAM-", 5) == 0 ? PROP_STRINGPREP : 0;
+
+if ( !client_prop(sctx, GSASL_PASSWORD, ob->client_password, US"password",
+ flags, buffer, buffsize)
+ || !client_prop(sctx, GSASL_AUTHID, ob->client_username, US"username",
+ flags, buffer, buffsize)
+ || !client_prop(sctx, GSASL_AUTHZID, ob->client_authz, US"authz",
+ flags | 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);
+# ifdef CHANNELBIND_HACK
+ gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, CCS 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;
+
+ rc = gsasl_step64(sctx, CS s, CSS &outstr);
+
+ 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;
+ if (outstr && *outstr) 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:
+gsasl_finish(sctx);
+return yield;
}
static int
client_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock)
{
-int cbrc = GSASL_NO_CALLBACK;
-HDEBUG(D_auth)
- debug_printf("GNU SASL callback %d for %s/%s as client\n",
- prop, ablock->name, ablock->public_name);
-
-HDEBUG(D_auth)
- debug_printf("Client side NOT IMPLEMENTED: you should not see this!\n");
-
-return cbrc;
+HDEBUG(D_auth) debug_printf("GNU SASL callback %d for %s/%s as client\n",
+ prop, ablock->name, ablock->public_name);
+switch (prop)
+ {
+ case GSASL_AUTHZID:
+ HDEBUG(D_auth) debug_printf(" inquired for AUTHZID; not providing one\n");
+ break;
+ case GSASL_SCRAM_SALTED_PASSWORD:
+ HDEBUG(D_auth)
+ debug_printf(" inquired for SCRAM_SALTED_PASSWORD; not providing one\n");
+ break;
+ case GSASL_CB_TLS_UNIQUE:
+ HDEBUG(D_auth)
+ debug_printf(" inquired for CB_TLS_UNIQUE, filling in\n");
+ gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, CCS tls_out.channelbinding);
+ break;
+ }
+return GSASL_NO_CALLBACK;
}
/*************************************************
git://git.exim.org / exim.git / commitdiff