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skeyinit.c revision 1.20 
      1 /*	$NetBSD: skeyinit.c,v 1.20 2002/11/16 05:24:44 itojun Exp $	*/
      2 
      3 /* S/KEY v1.1b (skeyinit.c)
      4  *
      5  * Authors:
      6  *          Neil M. Haller <nmh (at) thumper.bellcore.com>
      7  *          Philip R. Karn <karn (at) chicago.qualcomm.com>
      8  *          John S. Walden <jsw (at) thumper.bellcore.com>
      9  *          Scott Chasin <chasin (at) crimelab.com>
     10  *
     11  * Modifications:
     12  *          Todd C. Miller <Todd.Miller (at) courtesan.com>
     13  *
     14  * S/KEY initialization and seed update
     15  */
     16 
     17 #include <sys/param.h>
     18 #include <sys/time.h>
     19 #include <sys/resource.h>
     20 
     21 #include <ctype.h>
     22 #include <err.h>
     23 #include <errno.h>
     24 #include <fcntl.h>
     25 #include <paths.h>
     26 #include <pwd.h>
     27 #include <stdio.h>
     28 #include <stdlib.h>
     29 #include <string.h>
     30 #include <time.h>
     31 #include <unistd.h>
     32 
     33 #include <skey.h>
     34 
     35 #ifndef SKEY_NAMELEN
     36 #define SKEY_NAMELEN    4
     37 #endif
     38 
     39 int main __P((int, char **));
     40 
     41 int main(int argc, char **argv)
     42 {
     43 	int     rval, nn, i, l;
     44 	int n = 0, defaultsetup = 1, zerokey = 0, hexmode = 0;
     45 	time_t  now;
     46 	char	hostname[MAXHOSTNAMELEN + 1];
     47 	char    seed[SKEY_MAX_PW_LEN+2], key[SKEY_BINKEY_SIZE], defaultseed[SKEY_MAX_SEED_LEN+1];
     48 	char    passwd[SKEY_MAX_PW_LEN+2], passwd2[SKEY_MAX_PW_LEN+2], tbuf[27], buf[80];
     49 	char    lastc, me[LOGIN_NAME_MAX+1], *p, *pw, *ht = NULL;
     50 	const	char *salt;
     51 	struct	skey skey;
     52 	struct	passwd *pp;
     53 	struct	tm *tm;
     54 	int c;
     55 
     56 	/*
     57 	 * Make sure using stdin/stdout/stderr is safe
     58 	 * after opening any file.
     59 	 */
     60 	i = open(_PATH_DEVNULL, O_RDWR);
     61 	while (i >= 0 && i < 2)
     62 		i = dup(i);
     63 	if (i > 2)
     64 		close(i);
     65 
     66 	if (geteuid() != 0)
     67 		errx(1, "must be setuid root.");
     68 
     69 	if (gethostname(hostname, sizeof(hostname)) < 0)
     70 		err(1, "gethostname");
     71 
     72 	/*
     73 	 * Copy the hostname into the default seed, eliminating any
     74 	 * non alpha-numeric characters.
     75 	 */
     76 	for (i = 0, l = 0; l < sizeof(defaultseed); i++) {
     77 		if (hostname[i] == '\0') {
     78 			defaultseed[l] = hostname[i];
     79 			break;
     80 		}
     81 		if (isalnum(hostname[i]))
     82 			defaultseed[l++] = hostname[i];
     83 	}
     84 
     85 	defaultseed[SKEY_NAMELEN] = '\0';
     86 	(void)time(&now);
     87 	(void)sprintf(tbuf, "%05ld", (long) (now % 100000));
     88 	(void)strncat(defaultseed, tbuf, sizeof(defaultseed) - 5);
     89 
     90 	if ((pp = getpwuid(getuid())) == NULL)
     91 		err(1, "no user with uid %ld", (u_long)getuid());
     92 	(void)strlcpy(me, pp->pw_name, sizeof(me));
     93 
     94 	if ((pp = getpwnam(me)) == NULL)
     95 		err(1, "Who are you?");
     96 	salt = pp->pw_passwd;
     97 
     98 	while((c = getopt(argc, argv, "n:t:sxz")) != -1) {
     99 		switch(c) {
    100 			case 'n':
    101 				n = atoi(optarg);
    102 				if(n < 1 || n > SKEY_MAX_SEQ)
    103 					errx(1, "count must be between 1 and %d", SKEY_MAX_SEQ);
    104 				break;
    105 			case 't':
    106 				if(skey_set_algorithm(optarg) == NULL)
    107 					errx(1, "Unknown hash algorithm %s", optarg);
    108 				ht = optarg;
    109 				break;
    110 			case 's':
    111 				defaultsetup = 0;
    112 				break;
    113 			case 'x':
    114 				hexmode = 1;
    115 				break;
    116 			case 'z':
    117 				zerokey = 1;
    118 				break;
    119 			default:
    120 				errx(1, "Usage: %s [-n count] [-t md4|md5|sha1] [-s] [-x] [-z] [user]", argv[0]);
    121 		}
    122 	}
    123 
    124 	if(argc > optind) {
    125 		pp = getpwnam(argv[optind]);
    126 		if (pp == NULL)
    127 			errx(1, "User %s unknown", argv[optind]);
    128 		}
    129 
    130 	if (strcmp(pp->pw_name, me) != 0) {
    131 		if (getuid() != 0) {
    132 			/* Only root can change other's passwds */
    133 			errx(1, "Permission denied.");
    134 		}
    135 	}
    136 
    137 	if (getuid() != 0) {
    138 		pw = getpass("Password:");
    139 		p = crypt(pw, salt);
    140 
    141 		if (strcmp(p, pp->pw_passwd)) {
    142 			errx(1, "Password incorrect.");
    143 		}
    144 	}
    145 
    146 	rval = skeylookup(&skey, pp->pw_name);
    147 	switch (rval) {
    148 	case -1:
    149 		err(1, "cannot open database");
    150 	case 0:
    151 		/* comment out user if asked to */
    152 		if (zerokey)
    153 			exit(skeyzero(&skey, pp->pw_name));
    154 
    155 		printf("[Updating %s]\n", pp->pw_name);
    156 		printf("Old key: [%s] %s\n", skey_get_algorithm(), skey.seed);
    157 
    158 		/*
    159 		 * lets be nice if they have a skey.seed that
    160 		 * ends in 0-8 just add one
    161 		 */
    162 		l = strlen(skey.seed);
    163 		if (l > 0) {
    164 			lastc = skey.seed[l - 1];
    165 			if (isdigit((unsigned char)lastc) && lastc != '9') {
    166 				(void)strlcpy(defaultseed, skey.seed,
    167 				    sizeof(defaultseed));
    168 				defaultseed[l - 1] = lastc + 1;
    169 			}
    170 			if (isdigit((unsigned char)lastc) && lastc == '9' &&
    171 			    l < 16) {
    172 				(void)strncpy(defaultseed, skey.seed,
    173 				    sizeof(defaultseed));
    174 				defaultseed[l - 1] = '0';
    175 				defaultseed[l] = '0';
    176 				defaultseed[l + 1] = '\0';
    177 			}
    178 		}
    179 		break;
    180 	case 1:
    181 		if (zerokey)
    182 			errx(1, "You have no entry to zero.");
    183 		printf("[Adding %s]\n", pp->pw_name);
    184 		break;
    185 	}
    186 
    187 	if(n==0)
    188 		n = 99;
    189 
    190 	/* Set hash type if asked to */
    191 	if (ht) {
    192 		/* Need to zero out old key when changing algorithm */
    193 		if (strcmp(ht, skey_get_algorithm()) && skey_set_algorithm(ht))
    194 			zerokey = 1;
    195 	}
    196 
    197 	if (!defaultsetup) {
    198 		printf("You need the 6 english words generated from the \"skey\" command.\n");
    199 		for (i = 0;; i++) {
    200 			if (i >= 2)
    201 				exit(1);
    202 			printf("Enter sequence count from 1 to %d: ", SKEY_MAX_SEQ);
    203 			fgets(buf, sizeof(buf), stdin);
    204 			n = atoi(buf);
    205 			if (n > 0 && n < SKEY_MAX_SEQ)
    206 				break;	/* Valid range */
    207 			printf("\nError: Count must be between 0 and %d\n", SKEY_MAX_SEQ);
    208 		}
    209 
    210 		for (i = 0;; i++) {
    211 			if (i >= 2)
    212 				exit(1);
    213 
    214 			printf("Enter new seed [default %s]: ", defaultseed);
    215 			fflush(stdout);
    216 			fgets(seed, sizeof(seed), stdin);
    217 			rip(seed);
    218 			for (p = seed; *p; p++) {
    219 				if (isalpha(*p)) {
    220 					if (isupper(*p))
    221 						*p = tolower(*p);
    222 				} else if (!isdigit(*p)) {
    223 					(void)puts("Error: seed may only contain alphanumeric characters");
    224 					break;
    225 				}
    226 			}
    227 			if (*p == '\0')
    228 				break;  /* Valid seed */
    229 		}
    230 		if (strlen(seed) > SKEY_MAX_SEED_LEN) {
    231 			printf("Notice: Seed truncated to %d characters.\n", SKEY_MAX_SEED_LEN);
    232 			seed[SKEY_MAX_SEED_LEN] = '\0';
    233 		}
    234 		if (seed[0] == '\0')
    235 			(void)strlcpy(seed, defaultseed, sizeof(seed));
    236 
    237 		for (i = 0;; i++) {
    238 			if (i >= 2)
    239 				exit(1);
    240 
    241 			printf("otp-%s %d %s\ns/key access password: ",
    242 				skey_get_algorithm(), n, seed);
    243 			fgets(buf, sizeof(buf), stdin);
    244 			rip(buf);
    245 			backspace(buf);
    246 
    247 			if (buf[0] == '?') {
    248 				puts("Enter 6 English words from secure S/Key calculation.");
    249 				continue;
    250 			} else if (buf[0] == '\0') {
    251 				exit(1);
    252 			}
    253 			if (etob(key, buf) == 1 || atob8(key, buf) == 0)
    254 				break;	/* Valid format */
    255 			(void)puts("Invalid format - try again with 6 English words.");
    256 		}
    257 	} else {
    258 	/* Get user's secret password */
    259 	puts("Reminder - Only use this method if you are directly connected\n"
    260 	      "           or have an encrypted channel. If you are using telnet\n"
    261 	      "           or rlogin, exit with no password and use skeyinit -s.\n");
    262 
    263 	for (i = 0;; i++) {
    264 			if (i >= 2)
    265 				exit(1);
    266 
    267 			printf("Enter secret password: ");
    268 			readpass(passwd, sizeof(passwd));
    269 			if (passwd[0] == '\0')
    270 				exit(1);
    271 
    272 			if (strlen(passwd) < SKEY_MIN_PW_LEN) {
    273 				(void)fprintf(stderr,
    274 				    "Your password must be at least %d characters long.\n", SKEY_MIN_PW_LEN);
    275 				continue;
    276 			} else if (strcmp(passwd, pp->pw_name) == 0) {
    277 				(void)fputs("Your password may not be the same as your user name.\n", stderr);
    278 				continue;
    279 			}
    280 #if 0
    281 			else if (strspn(passwd, "abcdefghijklmnopqrstuvwxyz") == strlen(passwd)) {
    282 				(void)fputs("Your password must contain more than just lower case letters.\n"
    283 					    "Whitespace, numbers, and puctuation are suggested.\n", stderr);
    284 				continue;
    285 			}
    286 #endif
    287 			printf("Again secret password: ");
    288 			readpass(passwd2, sizeof(passwd));
    289 			if (passwd2[0] == '\0')
    290 				exit(1);
    291 
    292 			if (strcmp(passwd, passwd2) == 0)
    293 				break;
    294 
    295 			puts("Passwords do not match.");
    296 		}
    297 
    298 		/* Crunch seed and password into starting key */
    299 		(void)strlcpy(seed, defaultseed, sizeof(seed));
    300 		if (keycrunch(key, seed, passwd) != 0)
    301 			err(2, "key crunch failed");
    302 		nn = n;
    303 		while (nn-- != 0)
    304 			f(key);
    305 	}
    306 	(void)time(&now);
    307 	tm = localtime(&now);
    308 	(void)strftime(tbuf, sizeof(tbuf), " %b %d,%Y %T", tm);
    309 
    310 	if ((skey.val = (char *)malloc(16 + 1)) == NULL)
    311 		err(1, "Can't allocate memory");
    312 
    313 	/* Zero out old key if necessary (entry would change size) */
    314 	if (zerokey) {
    315 		(void)skeyzero(&skey, pp->pw_name);
    316 		/* Re-open keys file and seek to the end */
    317 		if (skeylookup(&skey, pp->pw_name) == -1)
    318 			err(1, "cannot open database");
    319 	}
    320 
    321 	btoa8(skey.val, key);
    322 
    323 	/*
    324 	 * Obtain an exclusive lock on the key file so we don't
    325 	 * clobber someone authenticating themselves at the same time.
    326 	 */
    327 	for (i = 0; i < 300; i++) {
    328 		if ((rval = flock(fileno(skey.keyfile), LOCK_EX|LOCK_NB)) == 0
    329 		    || errno != EWOULDBLOCK)
    330 			break;
    331 		usleep(100000);			/* Sleep for 0.1 seconds */
    332 	}
    333 	if (rval == -1)	{			/* Can't get exclusive lock */
    334 		errno = EAGAIN;
    335 		err(1, "cannot open database");
    336 	}
    337 
    338 	/* Don't save algorithm type for md4 (keep record length same) */
    339 	if (strcmp(skey_get_algorithm(), "md4") == 0)
    340 		(void)fprintf(skey.keyfile, "%s %04d %-16s %s %-21s\n",
    341 		    pp->pw_name, n, seed, skey.val, tbuf);
    342 	else
    343 		(void)fprintf(skey.keyfile, "%s %s %04d %-16s %s %-21s\n",
    344 		    pp->pw_name, skey_get_algorithm(), n, seed, skey.val, tbuf);
    345 
    346 	(void)fclose(skey.keyfile);
    347 
    348 	(void)printf("\nID %s skey is otp-%s %d %s\n", pp->pw_name,
    349 		     skey_get_algorithm(), n, seed);
    350 	(void)printf("Next login password: %s\n\n",
    351 		     hexmode ? put8(buf, key) : btoe(buf, key));
    352 
    353 	return(0);
    354 }
    355