[utils.git] / pam_krb5auto.c

/*
 *  pam_krb5auto - Gets initial credentials non-interactively
 *  Copyright (C) 2004 Fredrik Tolf (fredrik@dolda2000.com)
 *  
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *  
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *  
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdarg.h>
#include <malloc.h>
#include <syslog.h>
#include <krb5.h>
#include <pwd.h>
#include <errno.h>

#define PAM_SM_AUTH

#include <security/pam_modules.h>

#define DEF_INSTANCE "autologin"

struct options
{
    char *realm;
    char *instance;
    char *keytab;
    int debug;
    int forwardable;
    int renewable;
};

struct data
{
    krb5_context ctx;
    krb5_ccache cc;
    krb5_principal me;
    krb5_creds initcreds;
    int hascreds;
    uid_t uid;
    gid_t gid;
};

static void log(int prio, char *format, ...)
{
    va_list args;
    char buf[1024];
    
    va_start(args, format);
    snprintf(buf, sizeof(buf), "pam_krb5auto[%i]: %s", getpid(), format);
    vsyslog(prio, buf, args);
    va_end(args);
}

static struct options *parseopts(int argc, const char **argv)
{
    int i;
    struct options *opts;
    const char *p;
    int unit;
    
    opts = malloc(sizeof(*opts));
    memset(opts, 0, sizeof(*opts));
    for(i = 0; i < argc; i++) {
	if(!strncmp(argv[i], "realm=", 6))
	    opts->realm = strdup(argv[i] + 6);
	if(!strncmp(argv[i], "instance=", 9))
	    opts->instance = strdup(argv[i] + 9);
	if(!strncmp(argv[i], "keytab=", 7))
	    opts->keytab = strdup(argv[i] + 7);
	if(!strncmp(argv[i], "renew=", 6)) {
	    p = argv[i] + strlen(argv[i]) - 1;
	    unit = 1;
	    if((*p >= 'a') && (*p <= 'z')) {
		if(*p == 'm')
		    unit = 60;
		else if(*p == 'h')
		    unit = 3600;
		else if(*p == 'd')
		    unit = 86400;
		else
		    unit = 1;
	    }
	    opts->renewable = atoi(argv[i] + 6) * unit;
	}
	if(!strcmp(argv[i], "forwardable"))
	    opts->forwardable = 1;
	if(!strcmp(argv[i], "debug"))
	    opts->debug = 1;
    }
    return(opts);
}

static void freeopts(struct options *opts)
{
    if(opts->realm != NULL)
	free(opts->realm);
    if(opts->instance != NULL)
	free(opts->instance);
    if(opts->keytab != NULL)
	free(opts->keytab);
    free(opts);
}

static void freedata(struct data *data)
{
    if(data->hascreds)
	krb5_free_cred_contents(data->ctx, &data->initcreds);
    if(data->cc != NULL)
	krb5_cc_close(data->ctx, data->cc);
    if(data->me != NULL)
	krb5_free_principal(data->ctx, data->me);
    if(data->ctx != NULL)
	krb5_free_context(data->ctx);
    free(data);
}

static void cleanupdata(pam_handle_t *pamh, struct data *data, int error_status)
{
    freedata(data);
}

static struct data *getdata(pam_handle_t *pamh, struct options *opts)
{
    int ret;
    struct data *data;
    char buf[1024];
    const char *user, *instance;
    struct passwd *pwent;
    
    data = NULL;
    pam_get_data(pamh, "krb5auto-data", (const void **)&data);
    if(data == NULL) {
	if(opts->debug)
	    log(LOG_DEBUG, "creating new instance");
	data = malloc(sizeof(*data));
	memset(data, 0, sizeof(*data));
	pam_get_user(pamh, &user, NULL);
	if(user == NULL) {
	    log(LOG_ERR, "could not get user name");
	    freedata(data);
	    return(NULL);
	}
	errno = 0;
	if((pwent = getpwnam(user)) == NULL) {
	    log(LOG_ERR, "could not user information for `%s': %s", user, (errno == 0)?"user not found":strerror(errno));
	    freedata(data);
	    return(NULL);
	}
	data->uid = pwent->pw_uid;
	data->gid = pwent->pw_gid;
	if((ret = krb5_init_context(&data->ctx)) != 0) {
	    log(LOG_CRIT, "could not create krb5 context: %s", error_message(ret));
	    freedata(data);
	    return(NULL);
	}
	if(opts->instance)
	    instance = opts->instance;
	else
	    instance = DEF_INSTANCE;
	if(opts->realm)
	    snprintf(buf, sizeof(buf), "%s/%s@%s", user, instance, opts->realm);
	else
	    snprintf(buf, sizeof(buf), "%s/%s", user, instance);
	if((ret = krb5_parse_name(data->ctx, buf, &data->me)) != 0) {
	    log(LOG_ERR, "could not parse principal name `%s': %s", buf, error_message(ret));
	    freedata(data);
	    return(NULL);
	}
	pam_set_data(pamh, "krb5auto-data", data, (void (*)(pam_handle_t *, void *, int))cleanupdata);
    }
    return(data);
}

static int savecreds(pam_handle_t *pamh, struct options *opts, struct data *data)
{
    int ret, fd;
    krb5_keytab kt;
    krb5_get_init_creds_opt icopts;
    char buf[1024], *ccname, *filename;
    
    krb5_get_init_creds_opt_init(&icopts);
    kt = NULL;
    
    if(opts->keytab) {
	if((ret = krb5_kt_resolve(data->ctx, opts->keytab, &kt)) != 0) {
	    log(LOG_ERR, "could not resolve keytab `%s': %s", opts->keytab, error_message(ret));
	    ret = PAM_SERVICE_ERR;
	    goto out;
	}
	if(opts->debug)
	    log(LOG_DEBUG, "using keytab `%s'", opts->keytab);
    }
    krb5_get_init_creds_opt_set_forwardable(&icopts, opts->forwardable);
    krb5_get_init_creds_opt_set_renew_life(&icopts, opts->renewable);
    if(data->hascreds) {
	krb5_free_cred_contents(data->ctx, &data->initcreds);
	data->hascreds = 0;
    }
    if((ret = krb5_get_init_creds_keytab(data->ctx, &data->initcreds, data->me, kt, 0, NULL, &icopts)) != 0) {
	log(LOG_ERR, "could not get credentials: %s", error_message(ret));
	ret = PAM_SERVICE_ERR;
	goto out;
    }
    data->hascreds = 1;
    if(opts->debug)
	log(LOG_DEBUG, "got creds successfully");
    snprintf(buf, sizeof(buf), "KRB5CCNAME=FILE:/tmp/krb5cc_%i_XXXXXX", data->uid);
    ccname = buf + sizeof("KRB5CCNAME=") - 1;
    filename = ccname + sizeof("FILE:") - 1;
    if((fd = mkstemp(filename)) < 0) {
	log(LOG_ERR, "could not create tempfile for credentials cache: %s", strerror(errno));
	ret = PAM_SERVICE_ERR;
	goto out;
    }
    close(fd);
    if(opts->debug)
	log(LOG_DEBUG, "created ccache `%s'", filename);
    if((ret = krb5_cc_resolve(data->ctx, ccname, &data->cc)) != 0) {
	log(LOG_ERR, "could not resolve ccache `%s': %s", ccname, error_message(ret));
	unlink(filename);
	ret = PAM_SERVICE_ERR;
	goto out;
    }
    if((ret = krb5_cc_initialize(data->ctx, data->cc, data->me)) != 0) {
	log(LOG_ERR, "could not initialize credentials cache `%s': %s", ccname, error_message(ret));
	unlink(filename);
	ret = PAM_SERVICE_ERR;
	goto out;
    }
    if((ret = krb5_cc_store_cred(data->ctx, data->cc, &data->initcreds)) != 0) {
	log(LOG_ERR, "could not store credentials: %s", error_message(ret));
	unlink(filename);
	ret = PAM_SERVICE_ERR;
	goto out;
    }
    chown(filename, data->uid, data->gid);
    pam_putenv(pamh, strdup(buf));
    if(opts->debug)
	log(LOG_DEBUG, "successfully initialized ccache");
    ret = PAM_SUCCESS;
    
 out:
    if(kt != NULL)
	krb5_kt_close(data->ctx, kt);
    return(ret);
}

static int delcreds(pam_handle_t *pamh, struct options *opts, struct data *data)
{
    if(opts->debug)
	log(LOG_DEBUG, "deleting credentials");
    if(data->hascreds) {
	krb5_free_cred_contents(data->ctx, &data->initcreds);
	data->hascreds = 0;
	if(opts->debug)
	    log(LOG_DEBUG, "freed internal creds");
    }
    if(data->cc != NULL) {
	krb5_cc_destroy(data->ctx, data->cc);
	data->cc = NULL;
	if(opts->debug)
	    log(LOG_DEBUG, "destroyed ccache");
    }
    return(PAM_SUCCESS);
}

PAM_EXTERN int pam_sm_authenticate(pam_handle_t *pamh, int flags, int argc, const char **argv)
{
    struct options *opts;
    
    opts = parseopts(argc, argv);
    if(opts->debug)
	log(LOG_DEBUG, "pam_sm_authenticate called");
    freeopts(opts);
    return(PAM_IGNORE);
}

PAM_EXTERN int pam_sm_setcred(pam_handle_t *pamh, int flags, int argc, const char **argv)
{
    struct options *opts;
    struct data *data;
    int ret;
    
    opts = parseopts(argc, argv);
    if(opts->debug)
	log(LOG_DEBUG, "pam_sm_setcred called");
    data = getdata(pamh, opts);
    if(data == NULL) {
	log(LOG_ERR, "could not get data, erroring out");
	return(PAM_SERVICE_ERR);
    }
    ret = PAM_SERVICE_ERR;
    if(flags & PAM_ESTABLISH_CRED) {
	ret = savecreds(pamh, opts, data);
    } else if(flags & PAM_DELETE_CRED) {
	ret = delcreds(pamh, opts, data);
    }
    freeopts(opts);
    return(ret);
}

/*
 * Local Variables:
 * compile-command: "gcc -Wall -g --shared -fPIC -o pam_krb5auto.so pam_krb5auto.c -lkrb5"
 * End:
 */
Commit	Line	Data
7ccba695 DC	1	/*
	2	* pam_krb5auto - Gets initial credentials non-interactively
	3	* Copyright (C) 2004 Fredrik Tolf (fredrik@dolda2000.com)
	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License as published by
	7	* the Free Software Foundation; either version 2 of the License, or
	8	* (at your option) any later version.
	9	*
	10	* This program is distributed in the hope that it will be useful,
	11	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	13	* GNU General Public License for more details.
	14	*
	15	* You should have received a copy of the GNU General Public License
	16	* along with this program; if not, write to the Free Software
	17	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	18	*/
dc647f87	19	#include <stdlib.h>
2febc19a	20	#include <stdio.h>
dc647f87	21	#include <unistd.h>
2febc19a DC	22	#include <string.h>
	23	#include <stdarg.h>
	24	#include <malloc.h>
324b1cfb	25	#include <syslog.h>
dc647f87	26	#include <krb5.h>
eb2a40de DC	27	#include <pwd.h>
eb2a40de DC	28	#include <errno.h>
dc647f87 DC	29
	30	#define PAM_SM_AUTH
	31
	32	#include <security/pam_modules.h>
	33
2febc19a DC	34	#define DEF_INSTANCE "autologin"
	35
	36	struct options
	37	{
	38	char *realm;
	39	char *instance;
	40	char *keytab;
	41	int debug;
eb2a40de DC	42	int forwardable;
eb2a40de DC	43	int renewable;
2febc19a DC	44	};
	45
	46	struct data
	47	{
	48	krb5_context ctx;
	49	krb5_ccache cc;
	50	krb5_principal me;
eb2a40de DC	51	krb5_creds initcreds;
	52	int hascreds;
	53	uid_t uid;
e1427cb7	54	gid_t gid;
2febc19a DC	55	};
	56
	57	static void log(int prio, char *format, ...)
	58	{
	59	va_list args;
	60	char buf[1024];
	61
	62	va_start(args, format);
	63	snprintf(buf, sizeof(buf), "pam_krb5auto[%i]: %s", getpid(), format);
	64	vsyslog(prio, buf, args);
	65	va_end(args);
	66	}
	67
	68	static struct options parseopts(int argc, const char *argv)
	69	{
	70	int i;
	71	struct options *opts;
7dc0e19e DC	72	const char *p;
7dc0e19e DC	73	int unit;
2febc19a DC	74
	75	opts = malloc(sizeof(*opts));
	76	memset(opts, 0, sizeof(*opts));
	77	for(i = 0; i < argc; i++) {
	78	if(!strncmp(argv[i], "realm=", 6))
	79	opts->realm = strdup(argv[i] + 6);
	80	if(!strncmp(argv[i], "instance=", 9))
	81	opts->instance = strdup(argv[i] + 9);
	82	if(!strncmp(argv[i], "keytab=", 7))
	83	opts->keytab = strdup(argv[i] + 7);
7dc0e19e DC	84	if(!strncmp(argv[i], "renew=", 6)) {
	85	p = argv[i] + strlen(argv[i]) - 1;
	86	unit = 1;
	87	if((p >= 'a') && (p <= 'z')) {
	88	if(*p == 'm')
	89	unit = 60;
	90	else if(*p == 'h')
	91	unit = 3600;
	92	else if(*p == 'd')
	93	unit = 86400;
	94	else
	95	unit = 1;
	96	}
	97	opts->renewable = atoi(argv[i] + 6) * unit;
	98	}
eb2a40de DC	99	if(!strcmp(argv[i], "forwardable"))
eb2a40de DC	100	opts->forwardable = 1;
2febc19a DC	101	if(!strcmp(argv[i], "debug"))
	102	opts->debug = 1;
	103	}
	104	return(opts);
	105	}
	106
	107	static void freeopts(struct options *opts)
	108	{
	109	if(opts->realm != NULL)
	110	free(opts->realm);
	111	if(opts->instance != NULL)
	112	free(opts->instance);
	113	if(opts->keytab != NULL)
	114	free(opts->keytab);
	115	free(opts);
	116	}
	117
	118	static void freedata(struct data *data)
	119	{
eb2a40de DC	120	if(data->hascreds)
	121	krb5_free_cred_contents(data->ctx, &data->initcreds);
	122	if(data->cc != NULL)
	123	krb5_cc_close(data->ctx, data->cc);
2febc19a DC	124	if(data->me != NULL)
	125	krb5_free_principal(data->ctx, data->me);
	126	if(data->ctx != NULL)
	127	krb5_free_context(data->ctx);
	128	free(data);
	129	}
	130
	131	static void cleanupdata(pam_handle_t pamh, struct data data, int error_status)
	132	{
	133	freedata(data);
	134	}
	135
	136	static struct data getdata(pam_handle_t pamh, struct options *opts)
	137	{
	138	int ret;
	139	struct data *data;
	140	char buf[1024];
	141	const char user, instance;
eb2a40de	142	struct passwd *pwent;
2febc19a DC	143
	144	data = NULL;
	145	pam_get_data(pamh, "krb5auto-data", (const void **)&data);
	146	if(data == NULL) {
	147	if(opts->debug)
	148	log(LOG_DEBUG, "creating new instance");
	149	data = malloc(sizeof(*data));
	150	memset(data, 0, sizeof(*data));
eb2a40de DC	151	pam_get_user(pamh, &user, NULL);
	152	if(user == NULL) {
	153	log(LOG_ERR, "could not get user name");
	154	freedata(data);
	155	return(NULL);
	156	}
	157	errno = 0;
	158	if((pwent = getpwnam(user)) == NULL) {
	159	log(LOG_ERR, "could not user information for `%s': %s", user, (errno == 0)?"user not found":strerror(errno));
	160	freedata(data);
	161	return(NULL);
	162	}
	163	data->uid = pwent->pw_uid;
e1427cb7	164	data->gid = pwent->pw_gid;
2febc19a DC	165	if((ret = krb5_init_context(&data->ctx)) != 0) {
	166	log(LOG_CRIT, "could not create krb5 context: %s", error_message(ret));
	167	freedata(data);
	168	return(NULL);
	169	}
2febc19a DC	170	if(opts->instance)
	171	instance = opts->instance;
	172	else
	173	instance = DEF_INSTANCE;
	174	if(opts->realm)
	175	snprintf(buf, sizeof(buf), "%s/%s@%s", user, instance, opts->realm);
	176	else
	177	snprintf(buf, sizeof(buf), "%s/%s", user, instance);
	178	if((ret = krb5_parse_name(data->ctx, buf, &data->me)) != 0) {
	179	log(LOG_ERR, "could not parse principal name `%s': %s", buf, error_message(ret));
	180	freedata(data);
	181	return(NULL);
	182	}
	183	pam_set_data(pamh, "krb5auto-data", data, (void ()(pam_handle_t , void *, int))cleanupdata);
	184	}
	185	return(data);
	186	}
	187
eb2a40de	188	static int savecreds(pam_handle_t pamh, struct options opts, struct data *data)
2febc19a	189	{
eb2a40de DC	190	int ret, fd;
	191	krb5_keytab kt;
	192	krb5_get_init_creds_opt icopts;
	193	char buf[1024], ccname, filename;
	194
	195	krb5_get_init_creds_opt_init(&icopts);
	196	kt = NULL;
	197
	198	if(opts->keytab) {
	199	if((ret = krb5_kt_resolve(data->ctx, opts->keytab, &kt)) != 0) {
	200	log(LOG_ERR, "could not resolve keytab `%s': %s", opts->keytab, error_message(ret));
	201	ret = PAM_SERVICE_ERR;
	202	goto out;
	203	}
	204	if(opts->debug)
	205	log(LOG_DEBUG, "using keytab `%s'", opts->keytab);
	206	}
	207	krb5_get_init_creds_opt_set_forwardable(&icopts, opts->forwardable);
	208	krb5_get_init_creds_opt_set_renew_life(&icopts, opts->renewable);
	209	if(data->hascreds) {
	210	krb5_free_cred_contents(data->ctx, &data->initcreds);
	211	data->hascreds = 0;
	212	}
	213	if((ret = krb5_get_init_creds_keytab(data->ctx, &data->initcreds, data->me, kt, 0, NULL, &icopts)) != 0) {
	214	log(LOG_ERR, "could not get credentials: %s", error_message(ret));
	215	ret = PAM_SERVICE_ERR;
	216	goto out;
	217	}
	218	data->hascreds = 1;
	219	if(opts->debug)
	220	log(LOG_DEBUG, "got creds successfully");
	221	snprintf(buf, sizeof(buf), "KRB5CCNAME=FILE:/tmp/krb5cc_%i_XXXXXX", data->uid);
32601c6b DC	222	ccname = buf + sizeof("KRB5CCNAME=") - 1;
32601c6b DC	223	filename = ccname + sizeof("FILE:") - 1;
eb2a40de DC	224	if((fd = mkstemp(filename)) < 0) {
	225	log(LOG_ERR, "could not create tempfile for credentials cache: %s", strerror(errno));
	226	ret = PAM_SERVICE_ERR;
	227	goto out;
	228	}
	229	close(fd);
	230	if(opts->debug)
	231	log(LOG_DEBUG, "created ccache `%s'", filename);
	232	if((ret = krb5_cc_resolve(data->ctx, ccname, &data->cc)) != 0) {
	233	log(LOG_ERR, "could not resolve ccache `%s': %s", ccname, error_message(ret));
	234	unlink(filename);
	235	ret = PAM_SERVICE_ERR;
	236	goto out;
	237	}
	238	if((ret = krb5_cc_initialize(data->ctx, data->cc, data->me)) != 0) {
	239	log(LOG_ERR, "could not initialize credentials cache `%s': %s", ccname, error_message(ret));
	240	unlink(filename);
	241	ret = PAM_SERVICE_ERR;
	242	goto out;
	243	}
	244	if((ret = krb5_cc_store_cred(data->ctx, data->cc, &data->initcreds)) != 0) {
	245	log(LOG_ERR, "could not store credentials: %s", error_message(ret));
	246	unlink(filename);
	247	ret = PAM_SERVICE_ERR;
	248	goto out;
	249	}
e1427cb7	250	chown(filename, data->uid, data->gid);
eb2a40de DC	251	pam_putenv(pamh, strdup(buf));
	252	if(opts->debug)
	253	log(LOG_DEBUG, "successfully initialized ccache");
	254	ret = PAM_SUCCESS;
	255
	256	out:
	257	if(kt != NULL)
	258	krb5_kt_close(data->ctx, kt);
	259	return(ret);
	260	}
	261
	262	static int delcreds(pam_handle_t pamh, struct options opts, struct data *data)
	263	{
	264	if(opts->debug)
	265	log(LOG_DEBUG, "deleting credentials");
	266	if(data->hascreds) {
	267	krb5_free_cred_contents(data->ctx, &data->initcreds);
	268	data->hascreds = 0;
	269	if(opts->debug)
	270	log(LOG_DEBUG, "freed internal creds");
	271	}
	272	if(data->cc != NULL) {
	273	krb5_cc_destroy(data->ctx, data->cc);
	274	data->cc = NULL;
	275	if(opts->debug)
	276	log(LOG_DEBUG, "destroyed ccache");
	277	}
	278	return(PAM_SUCCESS);
2febc19a DC	279	}
	280
	281	PAM_EXTERN int pam_sm_authenticate(pam_handle_t pamh, int flags, int argc, const char *argv)
	282	{
eb2a40de DC	283	struct options *opts;
	284
	285	opts = parseopts(argc, argv);
	286	if(opts->debug)
	287	log(LOG_DEBUG, "pam_sm_authenticate called");
	288	freeopts(opts);
2febc19a DC	289	return(PAM_IGNORE);
	290	}
	291
	292	PAM_EXTERN int pam_sm_setcred(pam_handle_t pamh, int flags, int argc, const char *argv)
	293	{
	294	struct options *opts;
	295	struct data *data;
eb2a40de	296	int ret;
2febc19a DC	297
2febc19a DC	298	opts = parseopts(argc, argv);
4fb861a5 DC	299	if(opts->debug)
4fb861a5 DC	300	log(LOG_DEBUG, "pam_sm_setcred called");
2febc19a DC	301	data = getdata(pamh, opts);
	302	if(data == NULL) {
	303	log(LOG_ERR, "could not get data, erroring out");
	304	return(PAM_SERVICE_ERR);
	305	}
eb2a40de	306	ret = PAM_SERVICE_ERR;
2febc19a	307	if(flags & PAM_ESTABLISH_CRED) {
eb2a40de DC	308	ret = savecreds(pamh, opts, data);
	309	} else if(flags & PAM_DELETE_CRED) {
	310	ret = delcreds(pamh, opts, data);
2febc19a DC	311	}
2febc19a DC	312	freeopts(opts);
eb2a40de	313	return(ret);
2febc19a	314	}
dc647f87 DC	315
	316	/*
	317	* Local Variables:
4aa1b80b	318	* compile-command: "gcc -Wall -g --shared -fPIC -o pam_krb5auto.so pam_krb5auto.c -lkrb5"
dc647f87 DC	319	* End:
dc647f87 DC	320	*/