X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/4533e306fc21e0dc3cce32db0e2bfa146a5dd78c..14a806d6c13afdfb2f44dce64e50bffa6cb6869c:/src/src/auths/gsasl_exim.c diff --git a/src/src/auths/gsasl_exim.c b/src/src/auths/gsasl_exim.c index 614c179b7..db14a40e0 100644 --- a/src/src/auths/gsasl_exim.c +++ b/src/src/auths/gsasl_exim.c @@ -2,6 +2,7 @@ * 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. */ @@ -26,6 +27,7 @@ sense in all contexts. For some, we can do checks at init time. */ #include "../exim.h" +#define CHANNELBIND_HACK #ifndef AUTH_GSASL /* dummy function to satisfy compilers when we link in an "empty" file. */ @@ -37,12 +39,26 @@ static void dummy(int x) { dummy2(x-1); } #include #include "gsasl_exim.h" +#ifdef SUPPORT_I18N +# include +#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, @@ -68,14 +84,10 @@ int auth_gsasl_options_count = /* 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 */ }; @@ -125,8 +137,8 @@ to be set up. */ 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); @@ -152,48 +164,55 @@ if (!gsasl_ctx) /* 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; } @@ -207,21 +226,38 @@ 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) { - 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); @@ -261,9 +297,20 @@ 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", + 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)", @@ -273,10 +320,9 @@ if ((rc = gsasl_server_start(gsasl_ctx, CCS ob->server_mech, &sctx)) != GSASL_OK } /* 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); @@ -316,8 +362,9 @@ if (tls_in.channelbinding) { 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) @@ -375,7 +422,7 @@ do { } 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) { @@ -454,12 +501,13 @@ expand_nmax = 0; 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) @@ -470,13 +518,14 @@ switch (prop) 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""; @@ -489,13 +538,14 @@ switch (prop) 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. */ @@ -509,6 +559,7 @@ switch (prop) 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 @@ -518,9 +569,9 @@ switch (prop) 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) @@ -535,6 +586,7 @@ switch (prop) 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); @@ -544,6 +596,7 @@ switch (prop) 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); @@ -553,6 +606,7 @@ switch (prop) 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 @@ -576,11 +630,11 @@ switch (prop) 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) @@ -604,7 +658,7 @@ switch (prop) 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; } @@ -615,6 +669,48 @@ return cbrc; } +/******************************************************************************/ + +#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 * *************************************************/ @@ -629,24 +725,149 @@ auth_gsasl_client( 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; } /*************************************************