[utils.git] / pam_krb5auto.c

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdarg.h>
#include <malloc.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;
    
    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))
	    opts->renewable = atoi(argv[i] + 6);
	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
dc647f87	1	#include <stdlib.h>
2febc19a	2	#include <stdio.h>
dc647f87	3	#include <unistd.h>
2febc19a DC	4	#include <string.h>
	5	#include <stdarg.h>
	6	#include <malloc.h>
dc647f87	7	#include <krb5.h>
eb2a40de DC	8	#include <pwd.h>
eb2a40de DC	9	#include <errno.h>
dc647f87 DC	10
	11	#define PAM_SM_AUTH
	12
	13	#include <security/pam_modules.h>
	14
2febc19a DC	15	#define DEF_INSTANCE "autologin"
	16
	17	struct options
	18	{
	19	char *realm;
	20	char *instance;
	21	char *keytab;
	22	int debug;
eb2a40de DC	23	int forwardable;
eb2a40de DC	24	int renewable;
2febc19a DC	25	};
	26
	27	struct data
	28	{
	29	krb5_context ctx;
	30	krb5_ccache cc;
	31	krb5_principal me;
eb2a40de DC	32	krb5_creds initcreds;
	33	int hascreds;
	34	uid_t uid;
e1427cb7	35	gid_t gid;
2febc19a DC	36	};
	37
	38	static void log(int prio, char *format, ...)
	39	{
	40	va_list args;
	41	char buf[1024];
	42
	43	va_start(args, format);
	44	snprintf(buf, sizeof(buf), "pam_krb5auto[%i]: %s", getpid(), format);
	45	vsyslog(prio, buf, args);
	46	va_end(args);
	47	}
	48
	49	static struct options parseopts(int argc, const char *argv)
	50	{
	51	int i;
	52	struct options *opts;
	53
	54	opts = malloc(sizeof(*opts));
	55	memset(opts, 0, sizeof(*opts));
	56	for(i = 0; i < argc; i++) {
	57	if(!strncmp(argv[i], "realm=", 6))
	58	opts->realm = strdup(argv[i] + 6);
	59	if(!strncmp(argv[i], "instance=", 9))
	60	opts->instance = strdup(argv[i] + 9);
	61	if(!strncmp(argv[i], "keytab=", 7))
	62	opts->keytab = strdup(argv[i] + 7);
eb2a40de DC	63	if(!strncmp(argv[i], "renew=", 6))
	64	opts->renewable = atoi(argv[i] + 6);
	65	if(!strcmp(argv[i], "forwardable"))
	66	opts->forwardable = 1;
2febc19a DC	67	if(!strcmp(argv[i], "debug"))
	68	opts->debug = 1;
	69	}
	70	return(opts);
	71	}
	72
	73	static void freeopts(struct options *opts)
	74	{
	75	if(opts->realm != NULL)
	76	free(opts->realm);
	77	if(opts->instance != NULL)
	78	free(opts->instance);
	79	if(opts->keytab != NULL)
	80	free(opts->keytab);
	81	free(opts);
	82	}
	83
	84	static void freedata(struct data *data)
	85	{
eb2a40de DC	86	if(data->hascreds)
	87	krb5_free_cred_contents(data->ctx, &data->initcreds);
	88	if(data->cc != NULL)
	89	krb5_cc_close(data->ctx, data->cc);
2febc19a DC	90	if(data->me != NULL)
	91	krb5_free_principal(data->ctx, data->me);
	92	if(data->ctx != NULL)
	93	krb5_free_context(data->ctx);
	94	free(data);
	95	}
	96
	97	static void cleanupdata(pam_handle_t pamh, struct data data, int error_status)
	98	{
	99	freedata(data);
	100	}
	101
	102	static struct data getdata(pam_handle_t pamh, struct options *opts)
	103	{
	104	int ret;
	105	struct data *data;
	106	char buf[1024];
	107	const char user, instance;
eb2a40de	108	struct passwd *pwent;
2febc19a DC	109
	110	data = NULL;
	111	pam_get_data(pamh, "krb5auto-data", (const void **)&data);
	112	if(data == NULL) {
	113	if(opts->debug)
	114	log(LOG_DEBUG, "creating new instance");
	115	data = malloc(sizeof(*data));
	116	memset(data, 0, sizeof(*data));
eb2a40de DC	117	pam_get_user(pamh, &user, NULL);
	118	if(user == NULL) {
	119	log(LOG_ERR, "could not get user name");
	120	freedata(data);
	121	return(NULL);
	122	}
	123	errno = 0;
	124	if((pwent = getpwnam(user)) == NULL) {
	125	log(LOG_ERR, "could not user information for `%s': %s", user, (errno == 0)?"user not found":strerror(errno));
	126	freedata(data);
	127	return(NULL);
	128	}
	129	data->uid = pwent->pw_uid;
e1427cb7	130	data->gid = pwent->pw_gid;
2febc19a DC	131	if((ret = krb5_init_context(&data->ctx)) != 0) {
	132	log(LOG_CRIT, "could not create krb5 context: %s", error_message(ret));
	133	freedata(data);
	134	return(NULL);
	135	}
2febc19a DC	136	if(opts->instance)
	137	instance = opts->instance;
	138	else
	139	instance = DEF_INSTANCE;
	140	if(opts->realm)
	141	snprintf(buf, sizeof(buf), "%s/%s@%s", user, instance, opts->realm);
	142	else
	143	snprintf(buf, sizeof(buf), "%s/%s", user, instance);
	144	if((ret = krb5_parse_name(data->ctx, buf, &data->me)) != 0) {
	145	log(LOG_ERR, "could not parse principal name `%s': %s", buf, error_message(ret));
	146	freedata(data);
	147	return(NULL);
	148	}
	149	pam_set_data(pamh, "krb5auto-data", data, (void ()(pam_handle_t , void *, int))cleanupdata);
	150	}
	151	return(data);
	152	}
	153
eb2a40de	154	static int savecreds(pam_handle_t pamh, struct options opts, struct data *data)
2febc19a	155	{
eb2a40de DC	156	int ret, fd;
	157	krb5_keytab kt;
	158	krb5_get_init_creds_opt icopts;
	159	char buf[1024], ccname, filename;
	160
	161	krb5_get_init_creds_opt_init(&icopts);
	162	kt = NULL;
	163
	164	if(opts->keytab) {
	165	if((ret = krb5_kt_resolve(data->ctx, opts->keytab, &kt)) != 0) {
	166	log(LOG_ERR, "could not resolve keytab `%s': %s", opts->keytab, error_message(ret));
	167	ret = PAM_SERVICE_ERR;
	168	goto out;
	169	}
	170	if(opts->debug)
	171	log(LOG_DEBUG, "using keytab `%s'", opts->keytab);
	172	}
	173	krb5_get_init_creds_opt_set_forwardable(&icopts, opts->forwardable);
	174	krb5_get_init_creds_opt_set_renew_life(&icopts, opts->renewable);
	175	if(data->hascreds) {
	176	krb5_free_cred_contents(data->ctx, &data->initcreds);
	177	data->hascreds = 0;
	178	}
	179	if((ret = krb5_get_init_creds_keytab(data->ctx, &data->initcreds, data->me, kt, 0, NULL, &icopts)) != 0) {
	180	log(LOG_ERR, "could not get credentials: %s", error_message(ret));
	181	ret = PAM_SERVICE_ERR;
	182	goto out;
	183	}
	184	data->hascreds = 1;
	185	if(opts->debug)
	186	log(LOG_DEBUG, "got creds successfully");
	187	snprintf(buf, sizeof(buf), "KRB5CCNAME=FILE:/tmp/krb5cc_%i_XXXXXX", data->uid);
32601c6b DC	188	ccname = buf + sizeof("KRB5CCNAME=") - 1;
32601c6b DC	189	filename = ccname + sizeof("FILE:") - 1;
eb2a40de DC	190	if((fd = mkstemp(filename)) < 0) {
	191	log(LOG_ERR, "could not create tempfile for credentials cache: %s", strerror(errno));
	192	ret = PAM_SERVICE_ERR;
	193	goto out;
	194	}
	195	close(fd);
	196	if(opts->debug)
	197	log(LOG_DEBUG, "created ccache `%s'", filename);
	198	if((ret = krb5_cc_resolve(data->ctx, ccname, &data->cc)) != 0) {
	199	log(LOG_ERR, "could not resolve ccache `%s': %s", ccname, error_message(ret));
	200	unlink(filename);
	201	ret = PAM_SERVICE_ERR;
	202	goto out;
	203	}
	204	if((ret = krb5_cc_initialize(data->ctx, data->cc, data->me)) != 0) {
	205	log(LOG_ERR, "could not initialize credentials cache `%s': %s", ccname, error_message(ret));
	206	unlink(filename);
	207	ret = PAM_SERVICE_ERR;
	208	goto out;
	209	}
	210	if((ret = krb5_cc_store_cred(data->ctx, data->cc, &data->initcreds)) != 0) {
	211	log(LOG_ERR, "could not store credentials: %s", error_message(ret));
	212	unlink(filename);
	213	ret = PAM_SERVICE_ERR;
	214	goto out;
	215	}
e1427cb7	216	chown(filename, data->uid, data->gid);
eb2a40de DC	217	pam_putenv(pamh, strdup(buf));
	218	if(opts->debug)
	219	log(LOG_DEBUG, "successfully initialized ccache");
	220	ret = PAM_SUCCESS;
	221
	222	out:
	223	if(kt != NULL)
	224	krb5_kt_close(data->ctx, kt);
	225	return(ret);
	226	}
	227
	228	static int delcreds(pam_handle_t pamh, struct options opts, struct data *data)
	229	{
	230	if(opts->debug)
	231	log(LOG_DEBUG, "deleting credentials");
	232	if(data->hascreds) {
	233	krb5_free_cred_contents(data->ctx, &data->initcreds);
	234	data->hascreds = 0;
	235	if(opts->debug)
	236	log(LOG_DEBUG, "freed internal creds");
	237	}
	238	if(data->cc != NULL) {
	239	krb5_cc_destroy(data->ctx, data->cc);
	240	data->cc = NULL;
	241	if(opts->debug)
	242	log(LOG_DEBUG, "destroyed ccache");
	243	}
	244	return(PAM_SUCCESS);
2febc19a DC	245	}
	246
	247	PAM_EXTERN int pam_sm_authenticate(pam_handle_t pamh, int flags, int argc, const char *argv)
	248	{
eb2a40de DC	249	struct options *opts;
	250
	251	opts = parseopts(argc, argv);
	252	if(opts->debug)
	253	log(LOG_DEBUG, "pam_sm_authenticate called");
	254	freeopts(opts);
2febc19a DC	255	return(PAM_IGNORE);
	256	}
	257
	258	PAM_EXTERN int pam_sm_setcred(pam_handle_t pamh, int flags, int argc, const char *argv)
	259	{
	260	struct options *opts;
	261	struct data *data;
eb2a40de	262	int ret;
2febc19a DC	263
2febc19a DC	264	opts = parseopts(argc, argv);
4fb861a5 DC	265	if(opts->debug)
4fb861a5 DC	266	log(LOG_DEBUG, "pam_sm_setcred called");
2febc19a DC	267	data = getdata(pamh, opts);
	268	if(data == NULL) {
	269	log(LOG_ERR, "could not get data, erroring out");
	270	return(PAM_SERVICE_ERR);
	271	}
eb2a40de	272	ret = PAM_SERVICE_ERR;
2febc19a	273	if(flags & PAM_ESTABLISH_CRED) {
eb2a40de DC	274	ret = savecreds(pamh, opts, data);
	275	} else if(flags & PAM_DELETE_CRED) {
	276	ret = delcreds(pamh, opts, data);
2febc19a DC	277	}
2febc19a DC	278	freeopts(opts);
eb2a40de	279	return(ret);
2febc19a	280	}
dc647f87 DC	281
	282	/*
	283	* Local Variables:
4aa1b80b	284	* compile-command: "gcc -Wall -g --shared -fPIC -o pam_krb5auto.so pam_krb5auto.c -lkrb5"
dc647f87 DC	285	* End:
dc647f87 DC	286	*/