/* $OpenBSD: kerberos5.c,v 1.1 2005/05/24 03:43:56 deraadt Exp $ */ /*- * 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. 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. */ /* * This source code is no longer held under any constraint of USA * `cryptographic laws' since it was exported legally. The cryptographic * functions were removed from the code and a "Bones" distribution was * made. A Commodity Jurisdiction Request #012-94 was filed with the * USA State Department, who handed it to the Commerce department. The * code was determined to fall under General License GTDA under ECCN 5D96G, * and hence exportable. The cryptographic interfaces were re-added by Eric * Young, and then KTH proceeded to maintain the code in the free world. * */ /* * 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. */ /* $KTH: kerberos5.c,v 1.47 2001/01/09 18:45:33 assar Exp $ */ #ifdef KRB5 #include <arpa/telnet.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <netdb.h> #include <ctype.h> #include <pwd.h> #include <errno.h> #define Authenticator k5_Authenticator #include <kerberosV/krb5.h> #undef Authenticator #include <err.h> #include "encrypt.h" #include "auth.h" #include "misc.h" #if defined(DCE) int dfsk5ok = 0; int dfspag = 0; int dfsfwd = 0; #endif int forward_flags = 0; /* Flags get set in telnet/main.c on -f and -F */ int forward(int); int forwardable(int); /* 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 (Authenticator *); static unsigned char str_data[1024] = { IAC, SB, TELOPT_AUTHENTICATION, 0, AUTHTYPE_KERBEROS_V5, }; #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. */ #define KRB_FORWARD 4 /* Forwarded credentials follow */ #define KRB_FORWARD_ACCEPT 5 /* Forwarded credentials accepted */ #define KRB_FORWARD_REJECT 6 /* Forwarded credentials rejected */ static krb5_data auth; static krb5_ticket *ticket; static krb5_context context; static krb5_auth_context auth_context; int check_krb5_tickets() { krb5_error_code ret; krb5_context context; krb5_ccache ccache; krb5_principal principal; int retval = 1; ret = krb5_init_context(&context); if(ret) errx(1, "krb5_init_context failt: %d", ret); ret = krb5_cc_default(context, &ccache); if(ret) errx(1, "krb5_cc_default: %d", ret); ret = krb5_cc_get_principal (context, ccache, &principal); switch(ret) { case ENOENT: retval = 0; goto done; case 0: retval = 1; goto done; default: errx(1, "krb5_cc_get_principal: %d", ret); break; } done: krb5_free_context(context); return retval; } static int Data(Authenticator *ap, int type, void *d, int c) { unsigned char *p = str_data + 4; unsigned char *cd = (unsigned char *)d; if (c == -1) c = strlen(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(telnet_net_write(str_data, p - str_data)); } int kerberos5_init(Authenticator *ap, int server) { krb5_error_code ret; ret = krb5_init_context(&context); if (ret) return 0; if (server) { krb5_keytab kt; krb5_kt_cursor cursor; ret = krb5_kt_default(context, &kt); if (ret) return 0; ret = krb5_kt_start_seq_get (context, kt, &cursor); if (ret) { krb5_kt_close (context, kt); return 0; } krb5_kt_end_seq_get (context, kt, &cursor); krb5_kt_close (context, kt); str_data[3] = TELQUAL_REPLY; } else str_data[3] = TELQUAL_IS; return(1); } extern int net; static int kerberos5_send(char *name, Authenticator *ap) { krb5_error_code ret; krb5_ccache ccache; int ap_opts; krb5_data cksum_data; char foo[2]; if(check_krb5_tickets() != 1) return 0; if (!UserNameRequested) { if (auth_debug_mode) { printf("Kerberos V5: no user name supplied\r\n"); } return(0); } ret = krb5_cc_default(context, &ccache); if (ret) { if (auth_debug_mode) { printf("Kerberos V5: could not get default ccache: %s\r\n", krb5_get_err_text (context, ret)); } return 0; } if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL) ap_opts = AP_OPTS_MUTUAL_REQUIRED; else ap_opts = 0; ap_opts |= AP_OPTS_USE_SUBKEY; ret = krb5_auth_con_init (context, &auth_context); if (ret) { if (auth_debug_mode) { printf("Kerberos V5: krb5_auth_con_init failed (%s)\r\n", krb5_get_err_text(context, ret)); } return(0); } ret = krb5_auth_con_setaddrs_from_fd (context, auth_context, &net); if (ret) { if (auth_debug_mode) { printf ("Kerberos V5:" " krb5_auth_con_setaddrs_from_fd failed (%s)\r\n", krb5_get_err_text(context, ret)); } return(0); } krb5_auth_con_setkeytype (context, auth_context, KEYTYPE_DES); foo[0] = ap->type; foo[1] = ap->way; cksum_data.length = sizeof(foo); cksum_data.data = foo; { krb5_principal service; char sname[128]; ret = krb5_sname_to_principal (context, RemoteHostName, NULL, KRB5_NT_SRV_HST, &service); if(ret) { if (auth_debug_mode) { printf ("Kerberos V5:" " krb5_sname_to_principal(%s) failed (%s)\r\n", RemoteHostName, krb5_get_err_text(context, ret)); } return 0; } ret = krb5_unparse_name_fixed(context, service, sname, sizeof(sname)); if(ret) { if (auth_debug_mode) { printf ("Kerberos V5:" " krb5_unparse_name_fixed failed (%s)\r\n", krb5_get_err_text(context, ret)); } return 0; } printf("[ Trying %s (%s)... ]\r\n", name, sname); ret = krb5_mk_req_exact(context, &auth_context, ap_opts, service, &cksum_data, ccache, &auth); krb5_free_principal (context, service); } if (ret) { if (1 || auth_debug_mode) { printf("Kerberos V5: mk_req failed (%s)\r\n", krb5_get_err_text(context, ret)); } return(0); } if (!auth_sendname((unsigned char *)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); } int kerberos5_send_mutual(Authenticator *ap) { return kerberos5_send("mutual KERBEROS5", ap); } int kerberos5_send_oneway(Authenticator *ap) { return kerberos5_send("KERBEROS5", ap); } void kerberos5_is(Authenticator *ap, unsigned char *data, int cnt) { krb5_error_code ret; krb5_data outbuf; krb5_keyblock *key_block; char *name; krb5_principal server; int zero = 0; if (cnt-- < 1) return; switch (*data++) { case KRB_AUTH: auth.data = (char *)data; auth.length = cnt; auth_context = NULL; ret = krb5_auth_con_init (context, &auth_context); if (ret) { Data(ap, KRB_REJECT, "krb5_auth_con_init failed", -1); auth_finished(ap, AUTH_REJECT); if (auth_debug_mode) printf("Kerberos V5: krb5_auth_con_init failed (%s)\r\n", krb5_get_err_text(context, ret)); return; } ret = krb5_auth_con_setaddrs_from_fd (context, auth_context, &zero); if (ret) { Data(ap, KRB_REJECT, "krb5_auth_con_setaddrs_from_fd failed", -1); auth_finished(ap, AUTH_REJECT); if (auth_debug_mode) printf("Kerberos V5: " "krb5_auth_con_setaddrs_from_fd failed (%s)\r\n", krb5_get_err_text(context, ret)); return; } ret = krb5_sock_to_principal (context, 0, "host", KRB5_NT_SRV_HST, &server); if (ret) { Data(ap, KRB_REJECT, "krb5_sock_to_principal failed", -1); auth_finished(ap, AUTH_REJECT); if (auth_debug_mode) printf("Kerberos V5: " "krb5_sock_to_principal failed (%s)\r\n", krb5_get_err_text(context, ret)); return; } ret = krb5_rd_req(context, &auth_context, &auth, server, NULL, NULL, &ticket); krb5_free_principal (context, server); if (ret) { char *errbuf; asprintf(&errbuf, "Read req failed: %s", krb5_get_err_text(context, ret)); Data(ap, KRB_REJECT, errbuf, -1); if (auth_debug_mode) printf("%s\r\n", errbuf); free (errbuf); return; } { char foo[2]; foo[0] = ap->type; foo[1] = ap->way; ret = krb5_verify_authenticator_checksum(context, auth_context, foo, sizeof(foo)); if (ret) { char *errbuf; asprintf(&errbuf, "Bad checksum: %s", krb5_get_err_text(context, ret)); Data(ap, KRB_REJECT, errbuf, -1); if (auth_debug_mode) printf ("%s\r\n", errbuf); free(errbuf); return; } } ret = krb5_auth_con_getremotesubkey (context, auth_context, &key_block); if (ret) { Data(ap, KRB_REJECT, "krb5_auth_con_getremotesubkey failed", -1); auth_finished(ap, AUTH_REJECT); if (auth_debug_mode) printf("Kerberos V5: " "krb5_auth_con_getremotesubkey failed (%s)\r\n", krb5_get_err_text(context, ret)); return; } if (key_block == NULL) { ret = krb5_auth_con_getkey(context, auth_context, &key_block); } if (ret) { Data(ap, KRB_REJECT, "krb5_auth_con_getkey failed", -1); auth_finished(ap, AUTH_REJECT); if (auth_debug_mode) printf("Kerberos V5: " "krb5_auth_con_getkey failed (%s)\r\n", krb5_get_err_text(context, ret)); return; } if (key_block == NULL) { Data(ap, KRB_REJECT, "no subkey received", -1); auth_finished(ap, AUTH_REJECT); if (auth_debug_mode) printf("Kerberos V5: " "krb5_auth_con_getremotesubkey returned NULL key\r\n"); return; } if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL) { ret = krb5_mk_rep(context, auth_context, &outbuf); if (ret) { Data(ap, KRB_REJECT, "krb5_mk_rep failed", -1); auth_finished(ap, AUTH_REJECT); if (auth_debug_mode) printf("Kerberos V5: " "krb5_mk_rep failed (%s)\r\n", krb5_get_err_text(context, ret)); return; } Data(ap, KRB_RESPONSE, outbuf.data, outbuf.length); } if (krb5_unparse_name(context, ticket->client, &name)) name = 0; if(UserNameRequested && krb5_kuserok(context, ticket->client, UserNameRequested)) { Data(ap, KRB_ACCEPT, name, name ? -1 : 0); if (auth_debug_mode) { printf("Kerberos5 identifies him as ``%s''\r\n", name ? name : ""); } if(key_block->keytype == ETYPE_DES_CBC_MD5 || key_block->keytype == ETYPE_DES_CBC_MD4 || key_block->keytype == ETYPE_DES_CBC_CRC) { Session_Key skey; skey.type = SK_DES; skey.length = 8; skey.data = key_block->keyvalue.data; encrypt_session_key(&skey, 0); } } else { char *msg; asprintf (&msg, "user `%s' is not authorized to " "login as `%s'", name ? name : "<unknown>", UserNameRequested ? UserNameRequested : "<nobody>"); if (msg == NULL) Data(ap, KRB_REJECT, NULL, 0); else { Data(ap, KRB_REJECT, (void *)msg, -1); free(msg); } auth_finished (ap, AUTH_REJECT); krb5_free_keyblock_contents(context, key_block); break; } auth_finished(ap, AUTH_USER); krb5_free_keyblock_contents(context, key_block); break; case KRB_FORWARD: { struct passwd *pwd; char ccname[1024]; /* XXX */ krb5_data inbuf; krb5_ccache ccache; inbuf.data = (char *)data; inbuf.length = cnt; pwd = getpwnam (UserNameRequested); if (pwd == NULL) break; snprintf (ccname, sizeof(ccname), "FILE:/tmp/krb5cc_%u", pwd->pw_uid); ret = krb5_cc_resolve (context, ccname, &ccache); if (ret) { if (auth_debug_mode) printf ("Kerberos V5: could not get ccache: %s\r\n", krb5_get_err_text(context, ret)); break; } ret = krb5_cc_initialize (context, ccache, ticket->client); if (ret) { if (auth_debug_mode) printf ("Kerberos V5: could not init ccache: %s\r\n", krb5_get_err_text(context, ret)); break; } #if defined(DCE) esetenv("KRB5CCNAME", ccname, 1); #endif ret = krb5_rd_cred2 (context, auth_context, ccache, &inbuf); if(ret) { char *errbuf; asprintf (&errbuf, "Read forwarded creds failed: %s", krb5_get_err_text (context, ret)); if(errbuf == NULL) Data(ap, KRB_FORWARD_REJECT, NULL, 0); else Data(ap, KRB_FORWARD_REJECT, errbuf, -1); if (auth_debug_mode) printf("Could not read forwarded credentials: %s\r\n", errbuf); free (errbuf); } else { Data(ap, KRB_FORWARD_ACCEPT, 0, 0); #if defined(DCE) dfsfwd = 1; #endif } chown (ccname + 5, pwd->pw_uid, -1); if (auth_debug_mode) printf("Forwarded credentials obtained\r\n"); break; } default: if (auth_debug_mode) printf("Unknown Kerberos option %d\r\n", data[-1]); Data(ap, KRB_REJECT, 0, 0); break; } } void kerberos5_reply(Authenticator *ap, unsigned char *data, int cnt) { 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: { krb5_error_code ret; Session_Key skey; krb5_keyblock *keyblock; if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL && !mutual_complete) { printf("[ Kerberos V5 accepted you, but didn't provide mutual authentication! ]\r\n"); auth_send_retry(); return; } if (cnt) printf("[ Kerberos V5 accepts you as ``%.*s'' ]\r\n", cnt, data); else printf("[ Kerberos V5 accepts you ]\r\n"); ret = krb5_auth_con_getlocalsubkey (context, auth_context, &keyblock); if (ret) ret = krb5_auth_con_getkey (context, auth_context, &keyblock); if(ret) { printf("[ krb5_auth_con_getkey: %s ]\r\n", krb5_get_err_text(context, ret)); auth_send_retry(); return; } skey.type = SK_DES; skey.length = 8; skey.data = keyblock->keyvalue.data; encrypt_session_key(&skey, 0); krb5_free_keyblock_contents (context, keyblock); auth_finished(ap, AUTH_USER); if (forward_flags & OPTS_FORWARD_CREDS) kerberos5_forward(ap); 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 ret; inbuf.length = cnt; inbuf.data = (char *)data; ret = krb5_rd_rep(context, auth_context, &inbuf, &reply); if (ret) { printf("[ Mutual authentication failed: %s ]\r\n", krb5_get_err_text (context, ret)); auth_send_retry(); return; } krb5_free_ap_rep_enc_part(context, reply); mutual_complete = 1; } return; 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; default: if (auth_debug_mode) printf("Unknown Kerberos option %d\r\n", data[-1]); return; } } int kerberos5_status(Authenticator *ap, char *name, size_t name_sz, int level) { if (level < AUTH_USER) return(level); if (UserNameRequested && krb5_kuserok(context, ticket->client, UserNameRequested)) { strlcpy(name, UserNameRequested, name_sz); #if defined(DCE) dfsk5ok = 1; #endif 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(unsigned char *data, int cnt, unsigned char *buf, int buflen) { int i; buf[buflen-1] = '\0'; /* make sure its NULL terminated */ buflen -= 1; switch(data[3]) { case KRB_REJECT: /* Rejected (reason might follow) */ strlcpy((char *)buf, " REJECT ", buflen); goto common; case KRB_ACCEPT: /* Accepted (name might follow) */ strlcpy((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 */ strlcpy((char *)buf, " AUTH", buflen); goto common2; case KRB_RESPONSE: strlcpy((char *)buf, " RESPONSE", buflen); goto common2; case KRB_FORWARD: /* Forwarded credentials follow */ strlcpy((char *)buf, " FORWARD", buflen); goto common2; case KRB_FORWARD_ACCEPT: /* Forwarded credentials accepted */ strlcpy((char *)buf, " FORWARD_ACCEPT", buflen); goto common2; case KRB_FORWARD_REJECT: /* Forwarded credentials rejected */ /* (reason might follow) */ strlcpy((char *)buf, " FORWARD_REJECT", buflen); goto common2; default: snprintf(buf, buflen, " %d (unknown)", data[3]); common2: BUMP(buf, buflen); for (i = 4; i < cnt; i++) { snprintf(buf, buflen, " %d", data[i]); BUMP(buf, buflen); } break; } } void kerberos5_forward(Authenticator *ap) { krb5_error_code ret; krb5_ccache ccache; krb5_creds creds; krb5_kdc_flags flags; krb5_data out_data; krb5_principal principal; ret = krb5_cc_default (context, &ccache); if (ret) { if (auth_debug_mode) printf ("KerberosV5: could not get default ccache: %s\r\n", krb5_get_err_text (context, ret)); return; } ret = krb5_cc_get_principal (context, ccache, &principal); if (ret) { if (auth_debug_mode) printf ("KerberosV5: could not get principal: %s\r\n", krb5_get_err_text (context, ret)); return; } memset (&creds, 0, sizeof(creds)); creds.client = principal; ret = krb5_build_principal (context, &creds.server, strlen(principal->realm), principal->realm, "krbtgt", principal->realm, NULL); if (ret) { if (auth_debug_mode) printf ("KerberosV5: could not get principal: %s\r\n", krb5_get_err_text (context, ret)); return; } creds.times.endtime = 0; flags.i = 0; flags.b.forwarded = 1; if (forward_flags & OPTS_FORWARDABLE_CREDS) flags.b.forwardable = 1; ret = krb5_get_forwarded_creds (context, auth_context, ccache, flags.i, RemoteHostName, &creds, &out_data); if (ret) { if (auth_debug_mode) printf ("Kerberos V5: error getting forwarded creds: %s\r\n", krb5_get_err_text (context, ret)); return; } if(!Data(ap, KRB_FORWARD, out_data.data, out_data.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"); } } #if defined(DCE) /* if this was a K5 authentication try and join a PAG for the user. */ void kerberos5_dfspag(void) { if (dfsk5ok) { dfspag = krb5_dfs_pag(context, dfsfwd, ticket->client, UserNameRequested); } } #endif int kerberos5_set_forward(int on) { if(on == 0) forward_flags &= ~OPTS_FORWARD_CREDS; if(on == 1) forward_flags |= OPTS_FORWARD_CREDS; if(on == -1) forward_flags ^= OPTS_FORWARD_CREDS; return 0; } int kerberos5_set_forwardable(int on) { if(on == 0) forward_flags &= ~OPTS_FORWARDABLE_CREDS; if(on == 1) forward_flags |= OPTS_FORWARDABLE_CREDS; if(on == -1) forward_flags ^= OPTS_FORWARDABLE_CREDS; return 0; } #endif /* KRB5 */