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k5login.c revision 1.11
      1 /*	$NetBSD: k5login.c,v 1.11 2000/02/14 03:17:43 aidan Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1990 The Regents of the University of California.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 #ifndef lint
     38 #if 0
     39 static char sccsid[] = "@(#)klogin.c	5.11 (Berkeley) 7/12/92";
     40 #endif
     41 __RCSID("$NetBSD: k5login.c,v 1.11 2000/02/14 03:17:43 aidan Exp $");
     42 #endif /* not lint */
     43 
     44 #ifdef KERBEROS5
     45 #include <sys/param.h>
     46 #include <sys/syslog.h>
     47 #include <krb5/krb5.h>
     48 #include <com_err.h>
     49 #include <pwd.h>
     50 #include <netdb.h>
     51 #include <stdio.h>
     52 #include <stdlib.h>
     53 #include <string.h>
     54 #include <unistd.h>
     55 
     56 #define KRB5_DEFAULT_OPTIONS 0
     57 #define KRB5_DEFAULT_LIFE 60*60*10 /* 10 hours */
     58 
     59 krb5_context kcontext;
     60 
     61 int notickets;
     62 char *krbtkfile_env;
     63 extern char *tty;
     64 
     65 static char tkt_location[MAXPATHLEN];
     66 static krb5_creds forw_creds;
     67 int have_forward;
     68 static krb5_principal me, server;
     69 int use_krb5;
     70 
     71 int k5_read_creds __P((char *));
     72 int k5_write_creds __P((void));
     73 int klogin __P((struct passwd *, char *, char *, char *));
     74 void kdestroy __P((void));
     75 
     76 #ifndef krb5_realm_length
     77 #define krb5_realm_length(r)	((r).length)
     78 #endif
     79 #ifndef krb5_realm_data
     80 #define krb5_realm_data(r)	((r).data)
     81 #endif
     82 
     83 /*
     84  * Attempt to read forwarded kerberos creds
     85  *
     86  * return 0 on success (forwarded creds in memory)
     87  *        1 if no forwarded creds.
     88  */
     89 int
     90 k5_read_creds(username)
     91 	char *username;
     92 {
     93 	krb5_error_code code;
     94 	krb5_creds mcreds;
     95 	krb5_ccache ccache;
     96 
     97 	if (! use_krb5)
     98 		return(1);
     99 
    100 	have_forward = 0;
    101 	memset((char*) &mcreds, 0, sizeof(forw_creds));
    102 	memset((char*) &forw_creds, 0, sizeof(forw_creds));
    103 
    104 	code = krb5_cc_default(kcontext, &ccache);
    105 	if (code) {
    106 		com_err("login", code, "while getting default ccache");
    107 		return(1);
    108 	}
    109 
    110 	code = krb5_parse_name(kcontext, username, &me);
    111 	if (code) {
    112 		com_err("login", code, "when parsing name %s", username);
    113 		return(1);
    114 	}
    115 
    116 	mcreds.client = me;
    117 	code = krb5_build_principal_ext(kcontext, &mcreds.server,
    118 					krb5_realm_length(*krb5_princ_realm(kcontext, me)),
    119 					krb5_realm_data(*krb5_princ_realm(kcontext, me)),
    120 					KRB5_TGS_NAME_SIZE,
    121 					KRB5_TGS_NAME,
    122 					krb5_realm_length(*krb5_princ_realm(kcontext, me)),
    123 					krb5_realm_data(*krb5_princ_realm(kcontext, me)),
    124 					0);
    125 	if (code) {
    126 		com_err("login", code, "while building server name");
    127 		goto nuke_ccache;
    128 	}
    129 
    130 	code = krb5_cc_retrieve_cred(kcontext, ccache, 0,
    131 				       &mcreds, &forw_creds);
    132 	if (code) {
    133 		com_err("login", code, "while retrieving V5 initial ticket for copy");
    134 		goto nuke_ccache;
    135 	}
    136 	have_forward = 1;
    137 
    138 	strcpy(tkt_location, getenv("KRB5CCNAME"));
    139 	krbtkfile_env = tkt_location;
    140 	notickets = 0;
    141 
    142 nuke_ccache:
    143 	krb5_cc_destroy(kcontext, ccache);
    144 	return(!have_forward);
    145 }
    146 
    147 int
    148 k5_write_creds()
    149 {
    150 	krb5_error_code code;
    151 	krb5_ccache ccache;
    152 
    153 	if (! use_krb5)
    154 		return(1);
    155 	if (!have_forward)
    156 		return(1);
    157 	code = krb5_cc_default(kcontext, &ccache);
    158 	if (code) {
    159 		com_err("login", code, "while getting default ccache");
    160 		return(1);
    161 	}
    162 
    163 	code = krb5_cc_initialize(kcontext, ccache, me);
    164 	if (code) {
    165 		com_err("login", code, "while re-initializing V5 ccache as user");
    166 		goto nuke_ccache_contents;
    167 	}
    168 
    169 	code = krb5_cc_store_cred(kcontext, ccache, &forw_creds);
    170 	if (code) {
    171 		com_err("login", code, "while re-storing V5 ccache as user");
    172 		goto nuke_ccache_contents;
    173 	}
    174 
    175 nuke_ccache_contents:
    176 	krb5_free_cred_contents(kcontext, &forw_creds);
    177 	return(code != 0);
    178 }
    179 
    180 /*
    181  * Attempt to log the user in using Kerberos authentication
    182  *
    183  * return 0 on success (will be logged in)
    184  *	  1 if Kerberos failed (try local password in login)
    185  */
    186 int
    187 klogin(pw, instance, localhost, password)
    188 	struct passwd *pw;
    189 	char *instance, *localhost, *password;
    190 {
    191         krb5_error_code kerror;
    192 	krb5_creds my_creds;
    193 	krb5_timestamp now;
    194 	krb5_ccache ccache = NULL;
    195 	long lifetime = KRB5_DEFAULT_LIFE;
    196 	int options = KRB5_DEFAULT_OPTIONS;
    197 	char *realm, *client_name;
    198 	char *principal;
    199 
    200 	/*
    201 	 * Root logins don't use Kerberos.
    202 	 * If we have a realm, try getting a ticket-granting ticket
    203 	 * and using it to authenticate.  Otherwise, return
    204 	 * failure so that we can try the normal passwd file
    205 	 * for a password.  If that's ok, log the user in
    206 	 * without issuing any tickets.
    207 	 */
    208 	if (! use_krb5 ||
    209 	    strcmp(pw->pw_name, "root") == 0 ||
    210 	    krb5_get_default_realm(kcontext, &realm))
    211 		return (1);
    212 
    213 	/*
    214 	 * get TGT for local realm
    215 	 * tickets are stored in a file named TKT_ROOT plus uid
    216 	 * except for user.root tickets.
    217 	 */
    218 
    219 	if (strcmp(instance, "root") != 0)
    220 	    (void)snprintf(tkt_location, sizeof tkt_location,
    221 		"FILE:/tmp/krb5cc_%d.%s", pw->pw_uid, tty);
    222 	else
    223 	    (void)snprintf(tkt_location, sizeof tkt_location,
    224 		"FILE:/tmp/krb5cc_root_%d.%s", pw->pw_uid, tty);
    225 	krbtkfile_env = tkt_location;
    226 
    227 	principal = (char *)malloc(strlen(pw->pw_name)+strlen(instance)+2);
    228 	strcpy(principal, pw->pw_name);	/* XXX strcpy is safe */
    229 	if (strlen(instance)) {
    230 	    strcat(principal, "/");		/* XXX strcat is safe */
    231 	    strcat(principal, instance);	/* XXX strcat is safe */
    232 	}
    233 
    234 	if ((kerror = krb5_cc_resolve(kcontext, tkt_location, &ccache)) != 0) {
    235 	    syslog(LOG_NOTICE, "warning: %s while getting default ccache",
    236 		error_message(kerror));
    237 	    return(1);
    238 	}
    239 
    240 	if ((kerror = krb5_parse_name(kcontext, principal, &me)) != 0) {
    241 	    syslog(LOG_NOTICE, "warning: %s when parsing name %s",
    242 		error_message(kerror), principal);
    243 	    return(1);
    244 	}
    245 
    246 	if ((kerror = krb5_unparse_name(kcontext, me, &client_name)) != 0) {
    247 	    syslog(LOG_NOTICE, "warning: %s when unparsing name %s",
    248 		error_message(kerror), principal);
    249 	    return(1);
    250 	}
    251 
    252 	kerror = krb5_cc_initialize(kcontext, ccache, me);
    253 	if (kerror != 0) {
    254 	    syslog(LOG_NOTICE, "%s when initializing cache %s",
    255 		error_message(kerror), tkt_location);
    256 	    return(1);
    257 	}
    258 
    259 	memset((char *)&my_creds, 0, sizeof(my_creds));
    260 
    261 	my_creds.client = me;
    262 
    263 	if ((kerror = krb5_build_principal_ext(kcontext,
    264 					&server,
    265 					krb5_realm_length(*krb5_princ_realm(kcontext, me)),
    266 					krb5_realm_data(*krb5_princ_realm(kcontext, me)),
    267 					KRB5_TGS_NAME_SIZE,
    268 					KRB5_TGS_NAME,
    269 					krb5_realm_length(*krb5_princ_realm(kcontext, me)),
    270 					krb5_realm_data(*krb5_princ_realm(kcontext, me)),
    271 					0)) != 0) {
    272 	    syslog(LOG_NOTICE, "%s while building server name",
    273 		error_message(kerror));
    274 	    return(1);
    275 	}
    276 
    277 	my_creds.server = server;
    278 
    279 	if ((kerror = krb5_timeofday(kcontext, &now)) != 0) {
    280 	    syslog(LOG_NOTICE, "%s while getting time of day",
    281 		error_message(kerror));
    282 	    return(1);
    283 	}
    284 	my_creds.times.starttime = 0;	/* start timer when request
    285 					   gets to KDC */
    286 	my_creds.times.endtime = now + lifetime;
    287 	my_creds.times.renew_till = 0;
    288 
    289 	kerror = krb5_get_in_tkt_with_password(kcontext, options,
    290 					       NULL,
    291 					       NULL,
    292 					       NULL,
    293 					       password,
    294 					       ccache,
    295 					       &my_creds, 0);
    296 
    297 	krb5_free_principal(kcontext, server);
    298 
    299 	if (chown(&tkt_location[5], pw->pw_uid, pw->pw_gid) < 0)
    300 		syslog(LOG_ERR, "chown tkfile (%s): %m", &tkt_location[5]);
    301 
    302 	if (kerror) {
    303 	    if (kerror == KRB5KRB_AP_ERR_BAD_INTEGRITY)
    304 		printf("%s: Kerberos Password incorrect\n", principal);
    305 	    else
    306 		printf("%s while getting initial credentials\n", error_message(kerror));
    307 
    308 	    return(1);
    309 	}
    310 
    311 	/* Success */
    312 	notickets = 0;
    313 	return(0);
    314 }
    315 
    316 /*
    317  * Remove any credentials
    318  */
    319 void
    320 kdestroy()
    321 {
    322         krb5_error_code code;
    323 	krb5_ccache ccache = NULL;
    324 
    325 	if (! use_krb5 || krbtkfile_env == NULL)
    326 	    return;
    327 
    328 	code = krb5_cc_resolve(kcontext, krbtkfile_env, &ccache);
    329 	if (!code)
    330 	    code = krb5_cc_destroy(kcontext, ccache);
    331 }
    332 #endif
    333