/* * appl/telnet/libtelnet/kerberos5.c */ /*- * Copyright (c) 1991, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /* based on @(#)kerberos5.c 8.1 (Berkeley) 6/4/93 */ /* * Copyright (C) 1990 by the Massachusetts Institute of Technology * * Export of this software from the United States of America may * require a specific license from the United States Government. * It is the responsibility of any person or organization contemplating * export to obtain such a license before exporting. * * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and * distribute this software and its documentation for any purpose and * without fee is hereby granted, provided that the above copyright * notice appear in all copies and that both that copyright notice and * this permission notice appear in supporting documentation, and that * the name of M.I.T. not be used in advertising or publicity pertaining * to distribution of the software without specific, written prior * permission. M.I.T. makes no representations about the suitability of * this software for any purpose. It is provided "as is" without express * or implied warranty. */ #ifdef KRB5 #include #include #include "k5-int.h" #include "com_err.h" #include #include #ifdef HAVE_STDLIB_H #include #else extern char *malloc(); #endif #ifdef HAVE_STRING_H #include #else #include #endif #include "encrypt.h" #include "auth.h" #include "misc.h" extern auth_debug_mode; extern int net; #ifdef FORWARD int forward_flags = 0; /* Flags get set in telnet/main.c on -f and -F */ /* These values need to be the same as those defined in telnet/main.c. */ /* Either define them in both places, or put in some common header file. */ #define OPTS_FORWARD_CREDS 0x00000002 #define OPTS_FORWARDABLE_CREDS 0x00000001 void kerberos5_forward(); #endif /* FORWARD */ static unsigned char str_data[1024] = { IAC, SB, TELOPT_AUTHENTICATION, 0, AUTHTYPE_KERBEROS_V5, }; /*static unsigned char str_name[1024] = { IAC, SB, TELOPT_AUTHENTICATION, TELQUAL_NAME, };*/ #define KRB_AUTH 0 /* Authentication data follows */ #define KRB_REJECT 1 /* Rejected (reason might follow) */ #define KRB_ACCEPT 2 /* Accepted */ #define KRB_RESPONSE 3 /* Response for mutual auth. */ #ifdef FORWARD #define KRB_FORWARD 4 /* Forwarded credentials follow */ #define KRB_FORWARD_ACCEPT 5 /* Forwarded credentials accepted */ #define KRB_FORWARD_REJECT 6 /* Forwarded credentials rejected */ #endif /* FORWARD */ krb5_auth_context auth_context = 0; static krb5_data auth; /* telnetd gets session key from here */ static krb5_ticket * ticket = NULL; /* telnet matches the AP_REQ and AP_REP with this */ /* some compilers can't hack void *, so we use the Kerberos krb5_pointer, which is either void * or char *, depending on the compiler. */ #define Voidptr krb5_pointer krb5_keyblock *session_key = 0; char * telnet_srvtab = NULL; char * telnet_krb5_realm = NULL; static int Data(ap, type, d, c) Authenticator *ap; int type; Voidptr d; int c; { unsigned char *p = str_data + 4; unsigned char *cd = (unsigned char *)d; if (c == -1) c = strlen((char *)cd); if (auth_debug_mode) { printf("%s:%d: [%d] (%d)", str_data[3] == TELQUAL_IS ? ">>>IS" : ">>>REPLY", str_data[3], type, c); printd(d, c); printf("\r\n"); } *p++ = ap->type; *p++ = ap->way; *p++ = type; while (c-- > 0) { if ((*p++ = *cd++) == IAC) *p++ = IAC; } *p++ = IAC; *p++ = SE; if (str_data[3] == TELQUAL_IS) printsub('>', &str_data[2], p - &str_data[2]); return(net_write(str_data, p - str_data)); } krb5_context telnet_context = 0; int kerberos5_init(ap, server) Authenticator *ap; int server; { if (server) str_data[3] = TELQUAL_REPLY; else str_data[3] = TELQUAL_IS; if (telnet_context == 0) krb5_init_context(&telnet_context); krb5_init_ets(telnet_context); return(1); } void kerberos5_cleanup() { krb5_error_code retval; krb5_ccache ccache; char *ccname; if (telnet_context == 0) return; ccname = getenv(KRB5_ENV_CCNAME); if (ccname) { retval = krb5_cc_resolve(telnet_context, ccname, &ccache); if (!retval) retval = krb5_cc_destroy(telnet_context, ccache); } krb5_free_context(telnet_context); telnet_context = 0; } int kerberos5_send(ap) Authenticator *ap; { krb5_error_code r; krb5_ccache ccache; krb5_creds creds; /* telnet gets session key from here */ krb5_creds * new_creds = 0; int ap_opts; char type_check[2]; krb5_data check_data; #ifdef ENCRYPTION krb5_keyblock *newkey = 0; #endif /* ENCRYPTION */ if (!UserNameRequested) { if (auth_debug_mode) { printf("Kerberos V5: no user name supplied\r\n"); } return(0); } if ((r = krb5_cc_default(telnet_context, &ccache))) { if (auth_debug_mode) { printf("Kerberos V5: could not get default ccache\r\n"); } return(0); } memset((char *)&creds, 0, sizeof(creds)); if ((r = krb5_sname_to_principal(telnet_context, RemoteHostName, "host", KRB5_NT_SRV_HST, &creds.server))) { if (auth_debug_mode) printf("Kerberos V5: error while constructing service name: %s\r\n", error_message(r)); return(0); } if (telnet_krb5_realm != NULL) { krb5_data rdata; rdata.length = strlen(telnet_krb5_realm); rdata.data = (char *) malloc(rdata.length + 1); if (rdata.data == NULL) { fprintf(stderr, "malloc failed\n"); return(0); } strcpy(rdata.data, telnet_krb5_realm); krb5_princ_set_realm(telnet_context, creds.server, &rdata); } if ((r = krb5_cc_get_principal(telnet_context, ccache, &creds.client))) { if (auth_debug_mode) { printf("Kerberos V5: failure on principal (%s)\r\n", error_message(r)); } krb5_free_cred_contents(telnet_context, &creds); return(0); } creds.keyblock.enctype=ENCTYPE_DES_CBC_CRC; if ((r = krb5_get_credentials(telnet_context, 0, ccache, &creds, &new_creds))) { if (auth_debug_mode) { printf("Kerberos V5: failure on credentials(%s)\r\n", error_message(r)); } krb5_free_cred_contents(telnet_context, &creds); return(0); } if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL) ap_opts = AP_OPTS_MUTUAL_REQUIRED; else ap_opts = 0; #ifdef ENCRYPTION ap_opts |= AP_OPTS_USE_SUBKEY; #endif /* ENCRYPTION */ if (auth_context) { krb5_auth_con_free(telnet_context, auth_context); auth_context = 0; } if ((r = krb5_auth_con_init(telnet_context, &auth_context))) { if (auth_debug_mode) { printf("Kerberos V5: failed to init auth_context (%s)\r\n", error_message(r)); } return(0); } krb5_auth_con_setflags(telnet_context, auth_context, KRB5_AUTH_CONTEXT_RET_TIME); type_check[0] = ap->type; type_check[1] = ap->way; check_data.magic = KV5M_DATA; check_data.length = 2; check_data.data = (char *) &type_check; r = krb5_mk_req_extended(telnet_context, &auth_context, ap_opts, &check_data, new_creds, &auth); #ifdef ENCRYPTION krb5_auth_con_getlocalsubkey(telnet_context, auth_context, &newkey); if (session_key) { krb5_free_keyblock(telnet_context, session_key); session_key = 0; } if (newkey) { /* keep the key in our private storage, but don't use it yet---see kerberos5_reply() below */ if ((newkey->enctype != ENCTYPE_DES_CBC_CRC) && (newkey-> enctype != ENCTYPE_DES_CBC_MD5)) { if ((new_creds->keyblock.enctype == ENCTYPE_DES_CBC_CRC) || (new_creds->keyblock.enctype == ENCTYPE_DES_CBC_MD5)) /* use the session key in credentials instead */ krb5_copy_keyblock(telnet_context,&new_creds->keyblock, &session_key); else /* XXX ? */; } else { krb5_copy_keyblock(telnet_context, newkey, &session_key); } krb5_free_keyblock(telnet_context, newkey); } #endif /* ENCRYPTION */ krb5_free_cred_contents(telnet_context, &creds); krb5_free_creds(telnet_context, new_creds); if (r) { if (auth_debug_mode) { printf("Kerberos V5: mk_req failed (%s)\r\n", error_message(r)); } return(0); } if (!auth_sendname(UserNameRequested, strlen(UserNameRequested))) { if (auth_debug_mode) printf("Not enough room for user name\r\n"); return(0); } if (!Data(ap, KRB_AUTH, auth.data, auth.length)) { if (auth_debug_mode) printf("Not enough room for authentication data\r\n"); return(0); } if (auth_debug_mode) { printf("Sent Kerberos V5 credentials to server\r\n"); } return(1); } void kerberos5_is(ap, data, cnt) Authenticator *ap; unsigned char *data; int cnt; { int r = 0; krb5_principal server; krb5_keyblock *newkey = NULL; krb5_keytab keytabid = 0; krb5_data outbuf; #ifdef ENCRYPTION Session_Key skey; #endif char errbuf[128]; char *name; char *getenv(); krb5_data inbuf; krb5_authenticator *authenticator; if (cnt-- < 1) return; switch (*data++) { case KRB_AUTH: auth.data = (char *)data; auth.length = cnt; if (!r && !auth_context) r = krb5_auth_con_init(telnet_context, &auth_context); if (!r) { krb5_rcache rcache; r = krb5_auth_con_getrcache(telnet_context, auth_context, &rcache); if (!r && !rcache) { r = krb5_sname_to_principal(telnet_context, 0, 0, KRB5_NT_SRV_HST, &server); if (!r) { r = krb5_get_server_rcache(telnet_context, krb5_princ_component(telnet_context, server, 0), &rcache); krb5_free_principal(telnet_context, server); } } if (!r) r = krb5_auth_con_setrcache(telnet_context, auth_context, rcache); } if (!r && telnet_srvtab) r = krb5_kt_resolve(telnet_context, telnet_srvtab, &keytabid); if (!r) r = krb5_rd_req(telnet_context, &auth_context, &auth, NULL, keytabid, NULL, &ticket); if (r) { (void) strcpy(errbuf, "krb5_rd_req failed: "); (void) strcat(errbuf, error_message(r)); goto errout; } r = krb5_auth_con_getauthenticator(telnet_context, auth_context, &authenticator); if (r) { (void) strcpy(errbuf, "krb5_auth_con_getauthenticator failed: "); (void) strcat(errbuf, error_message(r)); goto errout; } if ((ap->way & AUTH_ENCRYPT_MASK) == AUTH_ENCRYPT_ON && !authenticator->checksum) { (void) strcpy(errbuf, "authenticator is missing required checksum"); goto errout; } if (authenticator->checksum) { char type_check[2]; krb5_checksum *cksum = authenticator->checksum; krb5_keyblock *key; type_check[0] = ap->type; type_check[1] = ap->way; r = krb5_auth_con_getkey(telnet_context, auth_context, &key); if (r) { (void) strcpy(errbuf, "krb5_auth_con_getkey failed: "); (void) strcat(errbuf, error_message(r)); goto errout; } r = krb5_verify_checksum(telnet_checksum, cksum->checksum_type, cksum, &type_check, 2, key->contents, key->length); if (r) { (void) strcpy(errbuf, "checksum verification failed: "); (void) strcat(errbuf, error_message(r)); goto errout; } krb5_free_keyblock(telnet_context, key); } krb5_free_authenticator(telnet_context, authenticator); if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL) { /* do ap_rep stuff here */ if ((r = krb5_mk_rep(telnet_context, auth_context, &outbuf))) { (void) strcpy(errbuf, "Make reply failed: "); (void) strcat(errbuf, error_message(r)); goto errout; } Data(ap, KRB_RESPONSE, outbuf.data, outbuf.length); } if (krb5_unparse_name(telnet_context, ticket->enc_part2 ->client, &name)) name = 0; Data(ap, KRB_ACCEPT, name, name ? -1 : 0); if (auth_debug_mode) { printf("Kerberos5 identifies him as ``%s''\r\n", name ? name : ""); } auth_finished(ap, AUTH_USER); if (name) free(name); krb5_auth_con_getremotesubkey(telnet_context, auth_context, &newkey); if (session_key) { krb5_free_keyblock(telnet_context, session_key); session_key = 0; } if (newkey) { krb5_copy_keyblock(telnet_context, newkey, &session_key); krb5_free_keyblock(telnet_context, newkey); } else { krb5_copy_keyblock(telnet_context, ticket->enc_part2->session, &session_key); } #ifdef ENCRYPTION skey.type = SK_DES; skey.length = 8; skey.data = session_key->contents; encrypt_session_key(&skey, 1); #endif break; #ifdef FORWARD case KRB_FORWARD: inbuf.length = cnt; inbuf.data = (char *)data; if ((r = krb5_auth_con_genaddrs(telnet_context, auth_context, net, KRB5_AUTH_CONTEXT_GENERATE_REMOTE_FULL_ADDR)) || (r = rd_and_store_for_creds(telnet_context, auth_context, &inbuf, ticket, UserNameRequested))) { char errbuf[128]; (void) strcpy(errbuf, "Read forwarded creds failed: "); (void) strcat(errbuf, error_message(r)); Data(ap, KRB_FORWARD_REJECT, errbuf, -1); if (auth_debug_mode) printf("Could not read forwarded credentials\r\n"); } else Data(ap, KRB_FORWARD_ACCEPT, 0, 0); if (auth_debug_mode) printf("Forwarded credentials obtained\r\n"); break; #endif /* FORWARD */ default: if (auth_debug_mode) printf("Unknown Kerberos option %d\r\n", data[-1]); Data(ap, KRB_REJECT, 0, 0); break; } return; errout: Data(ap, KRB_REJECT, errbuf, -1); if (auth_debug_mode) printf("%s\r\n", errbuf); if (auth_context) { krb5_auth_con_free(telnet_context, auth_context); auth_context = 0; } return; } void kerberos5_reply(ap, data, cnt) Authenticator *ap; unsigned char *data; int cnt; { #ifdef ENCRYPTION Session_Key skey; #endif static int mutual_complete = 0; if (cnt-- < 1) return; switch (*data++) { case KRB_REJECT: if (cnt > 0) { printf("[ Kerberos V5 refuses authentication because %.*s ]\r\n", cnt, data); } else printf("[ Kerberos V5 refuses authentication ]\r\n"); auth_send_retry(); return; case KRB_ACCEPT: if (!mutual_complete) { if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL) { printf("[ Kerberos V5 accepted you, but didn't provide mutual authentication! ]\r\n"); auth_send_retry(); return; } #ifdef ENCRYPTION if (session_key) { skey.type = SK_DES; skey.length = 8; skey.data = session_key->contents; encrypt_session_key(&skey, 0); } #endif /* ENCRYPTION */ } if (cnt) printf("[ Kerberos V5 accepts you as ``%.*s'' ]\r\n", cnt, data); else printf("[ Kerberos V5 accepts you ]\r\n"); auth_finished(ap, AUTH_USER); #ifdef FORWARD if (forward_flags & OPTS_FORWARD_CREDS) kerberos5_forward(ap); #endif /* FORWARD */ break; case KRB_RESPONSE: if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL) { /* the rest of the reply should contain a krb_ap_rep */ krb5_ap_rep_enc_part *reply; krb5_data inbuf; krb5_error_code r; inbuf.length = cnt; inbuf.data = (char *)data; if ((r = krb5_rd_rep(telnet_context, auth_context, &inbuf, &reply))) { printf("[ Mutual authentication failed: %s ]\r\n", error_message(r)); auth_send_retry(); return; } krb5_free_ap_rep_enc_part(telnet_context, reply); #ifdef ENCRYPTION if (session_key) { skey.type = SK_DES; skey.length = 8; skey.data = session_key->contents; encrypt_session_key(&skey, 0); } #endif /* ENCRYPTION */ mutual_complete = 1; } return; #ifdef FORWARD case KRB_FORWARD_ACCEPT: printf("[ Kerberos V5 accepted forwarded credentials ]\r\n"); return; case KRB_FORWARD_REJECT: printf("[ Kerberos V5 refuses forwarded credentials because %.*s ]\r\n", cnt, data); return; #endif /* FORWARD */ default: if (auth_debug_mode) printf("Unknown Kerberos option %d\r\n", data[-1]); return; } return; } int kerberos5_status(ap, name, level) Authenticator *ap; char *name; int level; { if (level < AUTH_USER) return(level); if (UserNameRequested && krb5_kuserok(telnet_context, ticket->enc_part2->client, UserNameRequested)) { strcpy(name, UserNameRequested); return(AUTH_VALID); } else return(AUTH_USER); } #define BUMP(buf, len) while (*(buf)) {++(buf), --(len);} #define ADDC(buf, len, c) if ((len) > 0) {*(buf)++ = (c); --(len);} void kerberos5_printsub(data, cnt, buf, buflen) unsigned char *data, *buf; int cnt, buflen; { char lbuf[32]; register int i; buf[buflen-1] = '\0'; /* make sure its NULL terminated */ buflen -= 1; switch(data[3]) { case KRB_REJECT: /* Rejected (reason might follow) */ strncpy((char *)buf, " REJECT ", buflen); goto common; case KRB_ACCEPT: /* Accepted (name might follow) */ strncpy((char *)buf, " ACCEPT ", buflen); common: BUMP(buf, buflen); if (cnt <= 4) break; ADDC(buf, buflen, '"'); for (i = 4; i < cnt; i++) ADDC(buf, buflen, data[i]); ADDC(buf, buflen, '"'); ADDC(buf, buflen, '\0'); break; case KRB_AUTH: /* Authentication data follows */ strncpy((char *)buf, " AUTH", buflen); goto common2; case KRB_RESPONSE: strncpy((char *)buf, " RESPONSE", buflen); goto common2; #ifdef FORWARD case KRB_FORWARD: /* Forwarded credentials follow */ strncpy((char *)buf, " FORWARD", buflen); goto common2; case KRB_FORWARD_ACCEPT: /* Forwarded credentials accepted */ strncpy((char *)buf, " FORWARD_ACCEPT", buflen); goto common2; case KRB_FORWARD_REJECT: /* Forwarded credentials rejected */ /* (reason might follow) */ strncpy((char *)buf, " FORWARD_REJECT", buflen); goto common2; #endif /* FORWARD */ default: sprintf(lbuf, " %d (unknown)", data[3]); strncpy((char *)buf, lbuf, buflen); common2: BUMP(buf, buflen); for (i = 4; i < cnt; i++) { sprintf(lbuf, " %d", data[i]); strncpy((char *)buf, lbuf, buflen); BUMP(buf, buflen); } break; } } #ifdef FORWARD void kerberos5_forward(ap) Authenticator *ap; { krb5_error_code r; krb5_ccache ccache; krb5_principal client = 0; krb5_principal server = 0; krb5_data forw_creds; forw_creds.data = 0; if ((r = krb5_cc_default(telnet_context, &ccache))) { if (auth_debug_mode) printf("Kerberos V5: could not get default ccache - %s\r\n", error_message(r)); return; } if ((r = krb5_cc_get_principal(telnet_context, ccache, &client))) { if (auth_debug_mode) printf("Kerberos V5: could not get default principal - %s\r\n", error_message(r)); goto cleanup; } if ((r = krb5_sname_to_principal(telnet_context, RemoteHostName, "host", KRB5_NT_SRV_HST, &server))) { if (auth_debug_mode) printf("Kerberos V5: could not make server principal - %s\r\n", error_message(r)); goto cleanup; } if ((r = krb5_auth_con_genaddrs(telnet_context, auth_context, net, KRB5_AUTH_CONTEXT_GENERATE_LOCAL_FULL_ADDR))) { if (auth_debug_mode) printf("Kerberos V5: could not gen local full address - %s\r\n", error_message(r)); goto cleanup; } if ((r = krb5_fwd_tgt_creds(telnet_context, auth_context, 0, client, server, ccache, forward_flags & OPTS_FORWARDABLE_CREDS, &forw_creds))) { if (auth_debug_mode) printf("Kerberos V5: error getting forwarded creds - %s\r\n", error_message(r)); goto cleanup; } /* Send forwarded credentials */ if (!Data(ap, KRB_FORWARD, forw_creds.data, forw_creds.length)) { if (auth_debug_mode) printf("Not enough room for authentication data\r\n"); } else { if (auth_debug_mode) printf("Forwarded local Kerberos V5 credentials to server\r\n"); } cleanup: if (client) krb5_free_principal(telnet_context, client); if (server) krb5_free_principal(telnet_context, server); if (forw_creds.data) free(forw_creds.data); krb5_cc_close(telnet_context, ccache); } #endif /* FORWARD */ #endif /* KRB5 */