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-rw-r--r--src/auths/cyrus_sasl.c513
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diff --git a/src/auths/cyrus_sasl.c b/src/auths/cyrus_sasl.c
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+/*************************************************
+* Exim - an Internet mail transport agent *
+*************************************************/
+
+/* Copyright (c) The Exim Maintainers 2020 - 2022 */
+/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* This code was originally contributed by Matthew Byng-Maddick */
+
+/* Copyright (c) A L Digital 2004 */
+
+/* A generic (mechanism independent) Cyrus SASL authenticator. */
+
+
+#include "../exim.h"
+
+
+/* We can't just compile this code and allow the library mechanism to omit the
+functions if they are not wanted, because we need to have the Cyrus SASL header
+available for compiling. Therefore, compile these functions only if
+AUTH_CYRUS_SASL is defined. However, some compilers don't like compiling empty
+modules, so keep them happy with a dummy when skipping the rest. Make it
+reference itself to stop picky compilers complaining that it is unused, and put
+in a dummy argument to stop even pickier compilers complaining about infinite
+loops. */
+
+#ifndef AUTH_CYRUS_SASL
+static void dummy(int x);
+static void dummy2(int x) { dummy(x-1); }
+static void dummy(int x) { dummy2(x-1); }
+#else
+
+
+#include <sasl/sasl.h>
+#include "cyrus_sasl.h"
+
+/* Options specific to the cyrus_sasl authentication mechanism. */
+
+optionlist auth_cyrus_sasl_options[] = {
+ { "server_hostname", opt_stringptr,
+ OPT_OFF(auth_cyrus_sasl_options_block, server_hostname) },
+ { "server_mech", opt_stringptr,
+ OPT_OFF(auth_cyrus_sasl_options_block, server_mech) },
+ { "server_realm", opt_stringptr,
+ OPT_OFF(auth_cyrus_sasl_options_block, server_realm) },
+ { "server_service", opt_stringptr,
+ OPT_OFF(auth_cyrus_sasl_options_block, server_service) }
+};
+
+/* Size of the options list. An extern variable has to be used so that its
+address can appear in the tables drtables.c. */
+
+int auth_cyrus_sasl_options_count =
+ sizeof(auth_cyrus_sasl_options)/sizeof(optionlist);
+
+/* Default private options block for the cyrus_sasl authentication method. */
+
+auth_cyrus_sasl_options_block auth_cyrus_sasl_option_defaults = {
+ US"smtp", /* server_service */
+ US"$primary_hostname", /* server_hostname */
+ NULL, /* server_realm */
+ NULL /* server_mech */
+};
+
+
+#ifdef MACRO_PREDEF
+
+/* Dummy values */
+void auth_cyrus_sasl_init(auth_instance *ablock) {}
+int auth_cyrus_sasl_server(auth_instance *ablock, uschar *data) {return 0;}
+int auth_cyrus_sasl_client(auth_instance *ablock, void * sx,
+ int timeout, uschar *buffer, int buffsize) {return 0;}
+gstring * auth_cyrus_sasl_version_report(gstring * g) {return NULL;}
+
+#else /*!MACRO_PREDEF*/
+
+
+
+
+/*************************************************
+* 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. */
+
+
+/* Auxiliary function, passed in data to sasl_server_init(). */
+
+static int
+mysasl_config(void *context, const char *plugin_name, const char *option,
+ const char **result, unsigned int *len)
+{
+if (context && !strcmp(option, "mech_list"))
+ {
+ *result = context;
+ if (len) *len = strlen(*result);
+ return SASL_OK;
+ }
+return SASL_FAIL;
+}
+
+/* Here's the real function */
+
+void
+auth_cyrus_sasl_init(auth_instance *ablock)
+{
+auth_cyrus_sasl_options_block *ob =
+ (auth_cyrus_sasl_options_block *)(ablock->options_block);
+const uschar *list, *listptr, *buffer;
+int rc, i;
+unsigned int len;
+rmark rs_point;
+uschar *expanded_hostname;
+char *realm_expanded;
+
+sasl_conn_t *conn;
+sasl_callback_t cbs[] = {
+ {SASL_CB_GETOPT, NULL, NULL },
+ {SASL_CB_LIST_END, NULL, NULL}};
+
+/* default the mechanism to our "public name" */
+
+if (!ob->server_mech) ob->server_mech = string_copy(ablock->public_name);
+
+if (!(expanded_hostname = expand_string(ob->server_hostname)))
+ log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: "
+ "couldn't expand server_hostname [%s]: %s",
+ ablock->name, ob->server_hostname, expand_string_message);
+
+realm_expanded = NULL;
+if ( ob->server_realm
+ && !(realm_expanded = CS expand_string(ob->server_realm)))
+ log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: "
+ "couldn't expand server_realm [%s]: %s",
+ ablock->name, ob->server_realm, expand_string_message);
+
+/* we're going to initialise the library to check that there is an
+authenticator of type whatever mechanism we're using */
+
+cbs[0].proc = (int(*)(void)) &mysasl_config;
+cbs[0].context = ob->server_mech;
+
+if ((rc = sasl_server_init(cbs, "exim")) != SASL_OK)
+ log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: "
+ "couldn't initialise Cyrus SASL library.", ablock->name);
+
+if ((rc = sasl_server_new(CS ob->server_service, CS expanded_hostname,
+ realm_expanded, NULL, NULL, NULL, 0, &conn)) != SASL_OK)
+ log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: "
+ "couldn't initialise Cyrus SASL server connection.", ablock->name);
+
+if ((rc = sasl_listmech(conn, NULL, "", ":", "", CCSS &list, &len, &i)) != SASL_OK)
+ log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: "
+ "couldn't get Cyrus SASL mechanism list.", ablock->name);
+
+i = ':';
+listptr = list;
+
+HDEBUG(D_auth)
+ {
+ debug_printf("Initialised Cyrus SASL service=\"%s\" fqdn=\"%s\" realm=\"%s\"\n",
+ ob->server_service, expanded_hostname, realm_expanded);
+ debug_printf("Cyrus SASL knows mechanisms: %s\n", list);
+ }
+
+/* the store_get / store_reset mechanism is hierarchical
+ the hierarchy is stored for us behind our back. This point
+ creates a hierarchy point for this function. */
+
+rs_point = store_mark();
+
+/* loop until either we get to the end of the list, or we match the
+public name of this authenticator */
+
+while ( (buffer = string_nextinlist(&listptr, &i, NULL, 0))
+ && strcmpic(buffer,ob->server_mech) );
+
+if (!buffer)
+ log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: "
+ "Cyrus SASL doesn't know about mechanism %s.", ablock->name, ob->server_mech);
+
+store_reset(rs_point);
+
+HDEBUG(D_auth) debug_printf("Cyrus SASL driver %s: %s initialised\n", ablock->name, ablock->public_name);
+
+/* make sure that if we get here then we're allowed to advertise. */
+ablock->server = TRUE;
+
+sasl_dispose(&conn);
+sasl_done();
+}
+
+/*************************************************
+* Server entry point *
+*************************************************/
+
+/* For interface, see auths/README */
+
+/* note, we don't care too much about memory allocation in this, because this is entirely
+within a shortlived child */
+
+int
+auth_cyrus_sasl_server(auth_instance *ablock, uschar *data)
+{
+auth_cyrus_sasl_options_block *ob =
+ (auth_cyrus_sasl_options_block *)(ablock->options_block);
+uschar *output, *out2, *input, *clear, *hname;
+uschar *debug = NULL; /* Stops compiler complaining */
+sasl_callback_t cbs[] = {{SASL_CB_LIST_END, NULL, NULL}};
+sasl_conn_t *conn;
+char * realm_expanded = NULL;
+int rc, firsttime = 1, clen, *negotiated_ssf_ptr = NULL, negotiated_ssf;
+unsigned int inlen, outlen;
+
+input = data;
+inlen = Ustrlen(data);
+
+HDEBUG(D_auth) debug = string_copy(data);
+
+hname = expand_string(ob->server_hostname);
+if (hname && ob->server_realm)
+ realm_expanded = CS expand_string(ob->server_realm);
+if (!hname || !realm_expanded && ob->server_realm)
+ {
+ auth_defer_msg = expand_string_message;
+ return DEFER;
+ }
+
+if (inlen)
+ {
+ if ((clen = b64decode(input, &clear)) < 0)
+ return BAD64;
+ input = clear;
+ inlen = clen;
+ }
+
+if ((rc = sasl_server_init(cbs, "exim")) != SASL_OK)
+ {
+ auth_defer_msg = US"couldn't initialise Cyrus SASL library";
+ return DEFER;
+ }
+
+rc = sasl_server_new(CS ob->server_service, CS hname, realm_expanded, NULL,
+ NULL, NULL, 0, &conn);
+
+HDEBUG(D_auth)
+ debug_printf("Initialised Cyrus SASL server connection; service=\"%s\" fqdn=\"%s\" realm=\"%s\"\n",
+ ob->server_service, hname, realm_expanded);
+
+if (rc != SASL_OK )
+ {
+ auth_defer_msg = US"couldn't initialise Cyrus SASL connection";
+ sasl_done();
+ return DEFER;
+ }
+
+if (tls_in.cipher)
+ {
+ if ((rc = sasl_setprop(conn, SASL_SSF_EXTERNAL, (sasl_ssf_t *) &tls_in.bits)) != SASL_OK)
+ {
+ HDEBUG(D_auth) debug_printf("Cyrus SASL EXTERNAL SSF set %d failed: %s\n",
+ tls_in.bits, sasl_errstring(rc, NULL, NULL));
+ auth_defer_msg = US"couldn't set Cyrus SASL EXTERNAL SSF";
+ sasl_done();
+ return DEFER;
+ }
+ else
+ HDEBUG(D_auth) debug_printf("Cyrus SASL set EXTERNAL SSF to %d\n", tls_in.bits);
+
+ /*XXX Set channel-binding here with sasl_channel_binding_t / SASL_CHANNEL_BINDING
+ Unclear what the "name" element does though, ditto the "critical" flag. */
+ }
+else
+ HDEBUG(D_auth) debug_printf("Cyrus SASL: no TLS, no EXTERNAL SSF set\n");
+
+/* So sasl_setprop() documents non-shorted IPv6 addresses which is incredibly
+annoying; looking at cyrus-imapd-2.3.x source, the IP address is constructed
+with their iptostring() function, which just wraps
+getnameinfo(..., NI_NUMERICHOST|NI_NUMERICSERV), which is equivalent to the
+inet_ntop which we wrap in our host_ntoa() function.
+
+So the docs are too strict and we shouldn't worry about :: contractions. */
+
+/* Set properties for remote and local host-ip;port */
+for (int i = 0; i < 2; ++i)
+ {
+ int propnum;
+ const uschar * label;
+ uschar * address_port;
+ const char *s_err;
+
+ if (i)
+ {
+ propnum = SASL_IPREMOTEPORT;
+ label = CUS"peer";
+ address_port = string_sprintf("%s;%d",
+ sender_host_address, sender_host_port);
+ }
+ else
+ {
+ propnum = SASL_IPLOCALPORT;
+ label = CUS"local";
+ address_port = string_sprintf("%s;%d", interface_address, interface_port);
+ }
+
+ if ((rc = sasl_setprop(conn, propnum, address_port)) != SASL_OK)
+ {
+ HDEBUG(D_auth)
+ {
+ s_err = sasl_errdetail(conn);
+ debug_printf("Failed to set %s SASL property: [%d] %s\n",
+ label, rc, s_err ? s_err : "<unknown reason>");
+ }
+ break;
+ }
+ HDEBUG(D_auth) debug_printf("Cyrus SASL set %s hostport to: %s\n",
+ label, address_port);
+ }
+
+for (rc = SASL_CONTINUE; rc == SASL_CONTINUE; )
+ {
+ if (firsttime)
+ {
+ firsttime = 0;
+ HDEBUG(D_auth) debug_printf("Calling sasl_server_start(%s,\"%s\")\n", ob->server_mech, debug);
+ rc = sasl_server_start(conn, CS ob->server_mech, inlen ? CS input : NULL, inlen,
+ CCSS &output, &outlen);
+ }
+ else
+ {
+ /* auth_get_data() takes a length-specfied block of binary
+ which can include zeroes; no terminating NUL is needed */
+
+ if ((rc = auth_get_data(&input, output, outlen)) != OK)
+ {
+ /* we couldn't get the data, so free up the library before
+ returning whatever error we get */
+ sasl_dispose(&conn);
+ sasl_done();
+ return rc;
+ }
+ inlen = Ustrlen(input);
+
+ HDEBUG(D_auth) debug = string_copy(input);
+ if (inlen)
+ {
+ if ((clen = b64decode(input, &clear)) < 0)
+ {
+ sasl_dispose(&conn);
+ sasl_done();
+ return BAD64;
+ }
+ input = clear;
+ inlen = clen;
+ }
+
+ HDEBUG(D_auth) debug_printf("Calling sasl_server_step(\"%s\")\n", debug);
+ rc = sasl_server_step(conn, CS input, inlen, CCSS &output, &outlen);
+ }
+
+ if (rc == SASL_BADPROT)
+ {
+ sasl_dispose(&conn);
+ sasl_done();
+ return UNEXPECTED;
+ }
+ if (rc == SASL_CONTINUE)
+ continue;
+
+ /* Get the username and copy it into $auth1 and $1. The former is now the
+ preferred variable; the latter is the original variable. */
+
+ if ((sasl_getprop(conn, SASL_USERNAME, (const void **)&out2)) != SASL_OK)
+ {
+ HDEBUG(D_auth)
+ debug_printf("Cyrus SASL library will not tell us the username: %s\n",
+ sasl_errstring(rc, NULL, NULL));
+ log_write(0, LOG_REJECT, "%s authenticator (%s): "
+ "Cyrus SASL username fetch problem: %s", ablock->name, ob->server_mech,
+ sasl_errstring(rc, NULL, NULL));
+ sasl_dispose(&conn);
+ sasl_done();
+ return FAIL;
+ }
+ auth_vars[0] = expand_nstring[1] = string_copy(out2);
+ expand_nlength[1] = Ustrlen(out2);
+ expand_nmax = 1;
+
+ switch (rc)
+ {
+ case SASL_FAIL: case SASL_BUFOVER: case SASL_BADMAC: case SASL_BADAUTH:
+ case SASL_NOAUTHZ: case SASL_ENCRYPT: case SASL_EXPIRED:
+ case SASL_DISABLED: case SASL_NOUSER:
+ /* these are considered permanent failure codes */
+ HDEBUG(D_auth)
+ debug_printf("Cyrus SASL permanent failure %d (%s)\n", rc, sasl_errstring(rc, NULL, NULL));
+ log_write(0, LOG_REJECT, "%s authenticator (%s): "
+ "Cyrus SASL permanent failure: %s", ablock->name, ob->server_mech,
+ sasl_errstring(rc, NULL, NULL));
+ sasl_dispose(&conn);
+ sasl_done();
+ return FAIL;
+
+ case SASL_NOMECH:
+ /* this is a temporary failure, because the mechanism is not
+ available for this user. If it wasn't available at all, we
+ shouldn't have got here in the first place... */
+
+ HDEBUG(D_auth)
+ debug_printf("Cyrus SASL temporary failure %d (%s)\n", rc, sasl_errstring(rc, NULL, NULL));
+ auth_defer_msg =
+ string_sprintf("Cyrus SASL: mechanism %s not available", ob->server_mech);
+ sasl_dispose(&conn);
+ sasl_done();
+ return DEFER;
+
+ case SASL_OK:
+ HDEBUG(D_auth)
+ debug_printf("Cyrus SASL %s authentication succeeded for %s\n",
+ ob->server_mech, auth_vars[0]);
+
+ if ((rc = sasl_getprop(conn, SASL_SSF, (const void **)(&negotiated_ssf_ptr)))!= SASL_OK)
+ {
+ HDEBUG(D_auth)
+ debug_printf("Cyrus SASL library will not tell us the SSF: %s\n",
+ sasl_errstring(rc, NULL, NULL));
+ log_write(0, LOG_REJECT, "%s authenticator (%s): "
+ "Cyrus SASL SSF value not available: %s", ablock->name, ob->server_mech,
+ sasl_errstring(rc, NULL, NULL));
+ sasl_dispose(&conn);
+ sasl_done();
+ return FAIL;
+ }
+ negotiated_ssf = *negotiated_ssf_ptr;
+ HDEBUG(D_auth)
+ debug_printf("Cyrus SASL %s negotiated SSF: %d\n", ob->server_mech, negotiated_ssf);
+ if (negotiated_ssf > 0)
+ {
+ HDEBUG(D_auth)
+ debug_printf("Exim does not implement SASL wrapping (needed for SSF %d).\n", negotiated_ssf);
+ log_write(0, LOG_REJECT, "%s authenticator (%s): "
+ "Cyrus SASL SSF %d not supported by Exim", ablock->name, ob->server_mech, negotiated_ssf);
+ sasl_dispose(&conn);
+ sasl_done();
+ return FAIL;
+ }
+
+ /* close down the connection, freeing up library's memory */
+ sasl_dispose(&conn);
+ sasl_done();
+
+ /* Expand server_condition as an authorization check */
+ return auth_check_serv_cond(ablock);
+
+ default:
+ /* Anything else is a temporary failure, and we'll let SASL print out
+ * the error string for us
+ */
+ HDEBUG(D_auth)
+ debug_printf("Cyrus SASL temporary failure %d (%s)\n", rc, sasl_errstring(rc, NULL, NULL));
+ auth_defer_msg =
+ string_sprintf("Cyrus SASL: %s", sasl_errstring(rc, NULL, NULL));
+ sasl_dispose(&conn);
+ sasl_done();
+ return DEFER;
+ }
+ }
+/* NOTREACHED */
+return 0; /* Stop compiler complaints */
+}
+
+/*************************************************
+* Diagnostic API *
+*************************************************/
+
+gstring *
+auth_cyrus_sasl_version_report(gstring * g)
+{
+const char * implementation, * version;
+sasl_version_info(&implementation, &version, NULL, NULL, NULL, NULL);
+g = string_fmt_append(g,
+ "Library version: Cyrus SASL: Compile: %d.%d.%d\n"
+ " Runtime: %s [%s]\n",
+ SASL_VERSION_MAJOR, SASL_VERSION_MINOR, SASL_VERSION_STEP,
+ version, implementation);
+return g;
+}
+
+/*************************************************
+* Client entry point *
+*************************************************/
+
+/* For interface, see auths/README */
+
+int
+auth_cyrus_sasl_client(
+ auth_instance *ablock, /* authenticator block */
+ void * sx, /* connexction */
+ int timeout, /* command timeout */
+ uschar *buffer, /* for reading response */
+ int buffsize) /* size of buffer */
+{
+/* We don't support clients (yet) in this implementation of cyrus_sasl */
+return FAIL;
+}
+
+#endif /*!MACRO_PREDEF*/
+#endif /* AUTH_CYRUS_SASL */
+
+/* End of cyrus_sasl.c */
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-18 23:09:41 +0000