X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/f1e05cc79778c693a1a2bad478ced44791922cce..HEAD:/src/src/auths/gsasl_exim.c diff --git a/src/src/auths/gsasl_exim.c b/src/src/auths/gsasl_exim.c deleted file mode 100644 index aef337c44..000000000 --- a/src/src/auths/gsasl_exim.c +++ /dev/null @@ -1,617 +0,0 @@ -/************************************************* -* Exim - an Internet mail transport agent * -*************************************************/ - -/* Copyright (c) University of Cambridge 1995 - 2012 */ -/* See the file NOTICE for conditions of use and distribution. */ - -/* Copyright (c) Twitter Inc 2012 - Author: Phil Pennock */ -/* 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) { dummy(x-1); } -#else - -#include -#include "gsasl_exim.h" - -/* 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[] = { - { "server_channelbinding", opt_bool, - (void *)(offsetof(auth_gsasl_options_block, server_channelbinding)) }, - { "server_hostname", opt_stringptr, - (void *)(offsetof(auth_gsasl_options_block, server_hostname)) }, - { "server_mech", opt_stringptr, - (void *)(offsetof(auth_gsasl_options_block, server_mech)) }, - { "server_password", opt_stringptr, - (void *)(offsetof(auth_gsasl_options_block, server_password)) }, - { "server_realm", opt_stringptr, - (void *)(offsetof(auth_gsasl_options_block, server_realm)) }, - { "server_scram_iter", opt_stringptr, - (void *)(offsetof(auth_gsasl_options_block, server_scram_iter)) }, - { "server_scram_salt", opt_stringptr, - (void *)(offsetof(auth_gsasl_options_block, server_scram_salt)) }, - { "server_service", opt_stringptr, - (void *)(offsetof(auth_gsasl_options_block, server_service)) } -}; -/* GSASL_SCRAM_SALTED_PASSWORD documented only for client, so not implementing -hooks to avoid cleartext passwords in the Exim server. */ - -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 = { - 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 */ -}; - -/* "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) -{ - char *p; - int rc, supported; - 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 == NULL) - 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 == NULL) { - rc = gsasl_init(&gsasl_ctx); - if (rc != 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. */ - rc = gsasl_server_mechlist(gsasl_ctx, &p); - if (rc != 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); - - supported = gsasl_client_support_p(gsasl_ctx, (const char *)ob->server_mech); - if (!supported) - 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 == NULL) && - (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->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 == NULL) && - 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->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 != NULL) ablock->server = TRUE; - ablock->client = FALSE; -} - - -/* 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); - - HDEBUG(D_auth) - debug_printf("GNU SASL Callback entered, prop=%d (loop prop=%d)\n", - prop, callback_loop); - - if (cb_state == NULL) { - HDEBUG(D_auth) debug_printf(" not from our server/client processing.\n"); - return GSASL_NO_CALLBACK; - } - - 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; -} - - -/************************************************* -* Server entry point * -*************************************************/ - -/* For interface, see auths/README */ - -int -auth_gsasl_server(auth_instance *ablock, uschar *initial_data) -{ - char *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); - - rc = gsasl_server_start(gsasl_ctx, (const char *)ob->server_mech, &sctx); - if (rc != 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 */ - - gsasl_session_hook_set(sctx, (void *)ablock); - cb_state.ablock = ablock; - cb_state.currently = CURRENTLY_SERVER; - gsasl_session_hook_set(sctx, (void *)&cb_state); - - tmps = CS expand_string(ob->server_service); - gsasl_property_set(sctx, GSASL_SERVICE, tmps); - tmps = CS expand_string(ob->server_hostname); - gsasl_property_set(sctx, GSASL_HOSTNAME, tmps); - if (ob->server_realm) { - tmps = CS expand_string(ob->server_realm); - if (tmps && *tmps) { - gsasl_property_set(sctx, GSASL_REALM, tmps); - } - } - /* We don't support protection layers. */ - gsasl_property_set(sctx, GSASL_QOPS, "qop-auth"); -#ifdef SUPPORT_TLS - if (tls_channelbinding_b64) { - /* 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 sesson 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* - */ - if (ob->server_channelbinding) { - HDEBUG(D_auth) debug_printf("Auth %s: Enabling channel-binding\n", - ablock->name); - gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, - (const char *) tls_channelbinding_b64); - } 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 { - rc = gsasl_step64(sctx, received, &to_send); - - switch (rc) { - 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; - } - - if ((rc == GSASL_NEEDS_MORE) || - (to_send && *to_send)) - exim_error = - auth_get_no64_data((uschar **)&received, (uschar *)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; - - 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; - - exim_rc = auth_check_some_cond(ablock, label, condition_string, FAIL); - - if (exim_rc == OK) { - return GSASL_OK; - } else if (exim_rc == DEFER) { - sasl_error_should_defer = TRUE; - return GSASL_AUTHENTICATION_ERROR; - } else if (exim_rc == FAIL) { - return GSASL_AUTHENTICATION_ERROR; - } - - 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; -} - -static int -server_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock) -{ - char *tmps; - uschar *propval; - int cbrc = GSASL_NO_CALLBACK; - int i; - auth_gsasl_options_block *ob = - (auth_gsasl_options_block *)(ablock->options_block); - - HDEBUG(D_auth) - debug_printf("GNU SASL callback %d for %s/%s as server\n", - prop, ablock->name, ablock->public_name); - - for (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 */ - propval = (uschar *) gsasl_property_fast(sctx, GSASL_AUTHID); - auth_vars[0] = expand_nstring[1] = propval ? propval : US""; - propval = (uschar *) gsasl_property_fast(sctx, GSASL_AUTHZID); - auth_vars[1] = expand_nstring[2] = propval ? propval : US""; - propval = (uschar *) gsasl_property_fast(sctx, GSASL_PASSWORD); - auth_vars[2] = expand_nstring[3] = propval ? propval : US""; - expand_nmax = 3; - for (i = 1; i <= 3; ++i) - expand_nlength[i] = Ustrlen(expand_nstring[i]); - - cbrc = condition_check(ablock, US"server_condition", ablock->server_condition); - checked_server_condition = TRUE; - break; - - case GSASL_VALIDATE_EXTERNAL: - if (ablock->server_condition == NULL) { - HDEBUG(D_auth) debug_printf("No server_condition supplied, to validate EXTERNAL.\n"); - cbrc = GSASL_AUTHENTICATION_ERROR; - break; - } - propval = (uschar *) gsasl_property_fast(sctx, GSASL_AUTHZID); - /* We always set $auth1, even if only to empty string. */ - auth_vars[0] = expand_nstring[1] = propval ? propval : US""; - expand_nlength[1] = Ustrlen(expand_nstring[1]); - expand_nmax = 1; - - cbrc = condition_check(ablock, - US"server_condition (EXTERNAL)", ablock->server_condition); - checked_server_condition = TRUE; - break; - - case GSASL_VALIDATE_ANONYMOUS: - if (ablock->server_condition == NULL) { - HDEBUG(D_auth) debug_printf("No server_condition supplied, to validate ANONYMOUS.\n"); - cbrc = GSASL_AUTHENTICATION_ERROR; - break; - } - propval = (uschar *) gsasl_property_fast(sctx, GSASL_ANONYMOUS_TOKEN); - /* We always set $auth1, even if only to empty string. */ - auth_vars[0] = expand_nstring[1] = propval ? propval : US""; - expand_nlength[1] = Ustrlen(expand_nstring[1]); - expand_nmax = 1; - - 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. */ - propval = (uschar *) gsasl_property_fast(sctx, GSASL_GSSAPI_DISPLAY_NAME); - auth_vars[0] = expand_nstring[1] = propval ? propval : US""; - propval = (uschar *) gsasl_property_fast(sctx, GSASL_AUTHZID); - auth_vars[1] = expand_nstring[2] = propval ? propval : US""; - expand_nmax = 2; - for (i = 1; i <= 2; ++i) - expand_nlength[i] = Ustrlen(expand_nstring[i]); - - /* 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_PASSWORD: - /* DIGEST-MD5: GSASL_AUTHID, GSASL_AUTHZID and GSASL_REALM - CRAM-MD5: GSASL_AUTHID - PLAIN: GSASL_AUTHID and GSASL_AUTHZID - LOGIN: GSASL_AUTHID - */ - if (ob->server_scram_iter) { - tmps = CS expand_string(ob->server_scram_iter); - gsasl_property_set(sctx, GSASL_SCRAM_ITER, tmps); - } - if (ob->server_scram_salt) { - tmps = CS expand_string(ob->server_scram_salt); - gsasl_property_set(sctx, GSASL_SCRAM_SALT, tmps); - } - /* 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. */ - propval = (uschar *) gsasl_property_fast(sctx, GSASL_AUTHID); - auth_vars[0] = expand_nstring[1] = propval ? propval : US""; - propval = (uschar *) gsasl_property_fast(sctx, GSASL_AUTHZID); - auth_vars[1] = expand_nstring[2] = propval ? propval : US""; - propval = (uschar *) gsasl_property_fast(sctx, GSASL_REALM); - auth_vars[2] = expand_nstring[3] = propval ? propval : US""; - expand_nmax = 3; - for (i = 1; i <= 3; ++i) - expand_nlength[i] = Ustrlen(expand_nstring[i]); - - tmps = CS expand_string(ob->server_password); - if (tmps == NULL) { - sasl_error_should_defer = expand_string_forcedfail ? FALSE : TRUE; - 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; - } - 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. */ - 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; -} - - -/************************************************* -* Client entry point * -*************************************************/ - -/* For interface, see auths/README */ - -int -auth_gsasl_client( - auth_instance *ablock, /* authenticator block */ - smtp_inblock *inblock, /* connection inblock */ - smtp_outblock *outblock, /* connection outblock */ - int timeout, /* command timeout */ - uschar *buffer, /* buffer for reading response */ - int buffsize) /* size of buffer */ -{ - HDEBUG(D_auth) - debug_printf("Client side NOT IMPLEMENTED: you should not see this!\n"); - /* NOT IMPLEMENTED */ - return FAIL; -} - -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; -} - -/************************************************* -* Diagnostic API * -*************************************************/ - -void -auth_gsasl_version_report(FILE *f) -{ - const char *runtime; - runtime = gsasl_check_version(NULL); - fprintf(f, "Library version: GNU SASL: Compile: %s\n" - " Runtime: %s\n", - GSASL_VERSION, runtime); -} - -#endif /* AUTH_GSASL */ - -/* End of gsasl_exim.c */