loginutils/passwd.c

   1 /* vi: set sw=4 ts=4: */
   2 #include <fcntl.h>
   3 #include <stdio.h>
   4 #include <string.h>
   5 #include <signal.h>
   6 #include <sys/stat.h>
   7 #include <sys/types.h>
   8 #include <unistd.h>
   9 #include <utime.h>
  10 #include <syslog.h>
  11 #include <time.h>
  12 #include <sys/resource.h>
  13 #include <errno.h>
  14
  15 #include "busybox.h"
  16
  17 static char crypt_passwd[128];
  18
  19 static int create_backup(const char *backup, FILE * fp);
  20 static int new_password(const struct passwd *pw, int amroot, int algo);
  21 static void set_filesize_limit(int blocks);
  22
  23
  24 static int get_algo(char *a)
  25 {
  26         int x = 1;                                      /* standard: MD5 */
  27
  28         if (strcasecmp(a, "des") == 0)
  29                 x = 0;
  30         return x;
  31 }
  32
  33
  34 static int update_passwd(const struct passwd *pw, char *crypt_pw)
  35 {
  36         char filename[1024];
  37         char buf[1025];
  38         char buffer[80];
  39         char username[32];
  40         char *pw_rest;
  41         int mask;
  42         int continued;
  43         FILE *fp;
  44         FILE *out_fp;
  45         struct stat sb;
  46         struct flock lock;
  47
  48 #ifdef CONFIG_FEATURE_SHADOWPASSWDS
  49         if (access(bb_path_shadow_file, F_OK) == 0) {
  50                 snprintf(filename, sizeof filename, "%s", bb_path_shadow_file);
  51         } else
  52 #endif
  53         {
  54                 snprintf(filename, sizeof filename, "%s", bb_path_passwd_file);
  55         }
  56
  57         if (((fp = fopen(filename, "r+")) == 0) || (fstat(fileno(fp), &sb))) {
  58                 /* return 0; */
  59                 return 1;
  60         }
  61
  62         /* Lock the password file before updating */
  63         lock.l_type = F_WRLCK;
  64         lock.l_whence = SEEK_SET;
  65         lock.l_start = 0;
  66         lock.l_len = 0;
  67         if (fcntl(fileno(fp), F_SETLK, &lock) < 0) {
  68                 fprintf(stderr, "%s: %s\n", filename, strerror(errno));
  69                 return 1;
  70         }
  71         lock.l_type = F_UNLCK;
  72
  73         snprintf(buf, sizeof buf, "%s-", filename);
  74         if (create_backup(buf, fp)) {
  75                 fcntl(fileno(fp), F_SETLK, &lock);
  76                 fclose(fp);
  77                 return 1;
  78         }
  79         snprintf(buf, sizeof buf, "%s+", filename);
  80         mask = umask(0777);
  81         out_fp = fopen(buf, "w");
  82         umask(mask);
  83         if ((!out_fp) || (fchmod(fileno(out_fp), sb.st_mode & 0777))
  84                 || (fchown(fileno(out_fp), sb.st_uid, sb.st_gid))) {
  85                 fcntl(fileno(fp), F_SETLK, &lock);
  86                 fclose(fp);
  87                 fclose(out_fp);
  88                 return 1;
  89         }
  90
  91         continued = 0;
  92         snprintf(username, sizeof username, "%s:", pw->pw_name);
  93         rewind(fp);
  94         while (!feof(fp)) {
  95                 fgets(buffer, sizeof buffer, fp);
  96                 if (!continued) {               // Check to see if we're updating this line.
  97                         if (strncmp(username, buffer, strlen(username)) == 0) { // we have a match.
  98                                 pw_rest = strchr(buffer, ':');
  99                                 *pw_rest++ = '\0';
 100                                 pw_rest = strchr(pw_rest, ':');
 101                                 fprintf(out_fp, "%s:%s%s", buffer, crypt_pw, pw_rest);
 102                         } else {
 103                                 fputs(buffer, out_fp);
 104                         }
 105                 } else {
 106                         fputs(buffer, out_fp);
 107                 }
 108                 if (buffer[strlen(buffer) - 1] == '\n') {
 109                         continued = 0;
 110                 } else {
 111                         continued = 1;
 112                 }
 113                 bzero(buffer, sizeof buffer);
 114         }
 115
 116         if (fflush(out_fp) || fsync(fileno(out_fp)) || fclose(out_fp)) {
 117                 unlink(buf);
 118                 fcntl(fileno(fp), F_SETLK, &lock);
 119                 fclose(fp);
 120                 return 1;
 121         }
 122         if (rename(buf, filename) < 0) {
 123                 fcntl(fileno(fp), F_SETLK, &lock);
 124                 fclose(fp);
 125                 return 1;
 126         } else {
 127                 fcntl(fileno(fp), F_SETLK, &lock);
 128                 fclose(fp);
 129                 return 0;
 130         }
 131 }
 132
 133
 134 extern int passwd_main(int argc, char **argv)
 135 {
 136         int amroot;
 137         char *cp;
 138         char *np;
 139         char *name;
 140         char *myname;
 141         int flag;
 142         int algo = 1;                           /* -a - password algorithm */
 143         int lflg = 0;                           /* -l - lock account */
 144         int uflg = 0;                           /* -u - unlock account */
 145         int dflg = 0;                           /* -d - delete password */
 146         const struct passwd *pw;
 147
 148 #ifdef CONFIG_FEATURE_SHADOWPASSWDS
 149         const struct spwd *sp;
 150 #endif                                                  /* CONFIG_FEATURE_SHADOWPASSWDS */
 151         amroot = (getuid() == 0);
 152         openlog("passwd", LOG_PID | LOG_CONS | LOG_NOWAIT, LOG_AUTH);
 153         while ((flag = getopt(argc, argv, "a:dlu")) != EOF) {
 154                 switch (flag) {
 155                 case 'a':
 156                         algo = get_algo(optarg);
 157                         break;
 158                 case 'd':
 159                         dflg++;
 160                         break;
 161                 case 'l':
 162                         lflg++;
 163                         break;
 164                 case 'u':
 165                         uflg++;
 166                         break;
 167                 default:
 168                         bb_show_usage();
 169                 }
 170         }
 171         myname = (char *) bb_xstrdup(bb_getpwuid(NULL, getuid(), -1));
 172         /* exits on error */
 173         if (optind < argc) {
 174                 name = argv[optind];
 175         } else {
 176                 name = myname;
 177         }
 178         if ((lflg || uflg || dflg) && (optind >= argc || !amroot)) {
 179                 bb_show_usage();
 180         }
 181         pw = getpwnam(name);
 182         if (!pw) {
 183                 bb_error_msg_and_die("Unknown user %s\n", name);
 184         }
 185         if (!amroot && pw->pw_uid != getuid()) {
 186                 syslog(LOG_WARNING, "can't change pwd for `%s'", name);
 187                 bb_error_msg_and_die("Permission denied.\n");
 188         }
 189 #ifdef CONFIG_FEATURE_SHADOWPASSWDS
 190         sp = getspnam(name);
 191         if (!sp) {
 192                 sp = (struct spwd *) pwd_to_spwd(pw);
 193         }
 194         cp = sp->sp_pwdp;
 195         np = sp->sp_namp;
 196 #else
 197         cp = pw->pw_passwd;
 198         np = name;
 199 #endif                                                  /* CONFIG_FEATURE_SHADOWPASSWDS */
 200
 201         safe_strncpy(crypt_passwd, cp, sizeof(crypt_passwd));
 202         if (!(dflg || lflg || uflg)) {
 203                 if (!amroot) {
 204                         if (cp[0] == '!') {
 205                                 syslog(LOG_WARNING, "password locked for `%s'", np);
 206                                 bb_error_msg_and_die( "The password for `%s' cannot be changed.\n", np);
 207                         }
 208                 }
 209                 printf("Changing password for %s\n", name);
 210                 if (new_password(pw, amroot, algo)) {
 211                         bb_error_msg_and_die( "The password for %s is unchanged.\n", name);
 212                 }
 213         } else if (lflg) {
 214                 if (crypt_passwd[0] != '!') {
 215                         memmove(&crypt_passwd[1], crypt_passwd,
 216                                         sizeof crypt_passwd - 1);
 217                         crypt_passwd[sizeof crypt_passwd - 1] = '\0';
 218                         crypt_passwd[0] = '!';
 219                 }
 220         } else if (uflg) {
 221                 if (crypt_passwd[0] == '!') {
 222                         memmove(crypt_passwd, &crypt_passwd[1],
 223                                         sizeof crypt_passwd - 1);
 224                 }
 225         } else if (dflg) {
 226                 crypt_passwd[0] = '\0';
 227         }
 228         set_filesize_limit(30000);
 229         signal(SIGHUP, SIG_IGN);
 230         signal(SIGINT, SIG_IGN);
 231         signal(SIGQUIT, SIG_IGN);
 232         umask(077);
 233         if (setuid(0)) {
 234                 syslog(LOG_ERR, "can't setuid(0)");
 235                 bb_error_msg_and_die( "Cannot change ID to root.\n");
 236         }
 237         if (!update_passwd(pw, crypt_passwd)) {
 238                 syslog(LOG_INFO, "password for `%s' changed by user `%s'", name,
 239                            myname);
 240                 printf("Password changed.\n");
 241         } else {
 242                 syslog(LOG_WARNING, "an error occurred updating the password file");
 243                 bb_error_msg_and_die("An error occurred updating the password file.\n");
 244         }
 245         return (0);
 246 }
 247
 248
 249
 250 static int create_backup(const char *backup, FILE * fp)
 251 {
 252         struct stat sb;
 253         struct utimbuf ub;
 254         FILE *bkfp;
 255         int c, mask;
 256
 257         if (fstat(fileno(fp), &sb))
 258                 /* return -1; */
 259                 return 1;
 260
 261         mask = umask(077);
 262         bkfp = fopen(backup, "w");
 263         umask(mask);
 264         if (!bkfp)
 265                 /* return -1; */
 266                 return 1;
 267
 268         /* TODO: faster copy, not one-char-at-a-time.  --marekm */
 269         rewind(fp);
 270         while ((c = getc(fp)) != EOF) {
 271                 if (putc(c, bkfp) == EOF)
 272                         break;
 273         }
 274         if (c != EOF || fflush(bkfp)) {
 275                 fclose(bkfp);
 276                 /* return -1; */
 277                 return 1;
 278         }
 279         if (fclose(bkfp))
 280                 /* return -1; */
 281                 return 1;
 282
 283         ub.actime = sb.st_atime;
 284         ub.modtime = sb.st_mtime;
 285         utime(backup, &ub);
 286         return 0;
 287 }
 288
 289 static int i64c(int i)
 290 {
 291         if (i <= 0)
 292                 return ('.');
 293         if (i == 1)
 294                 return ('/');
 295         if (i >= 2 && i < 12)
 296                 return ('0' - 2 + i);
 297         if (i >= 12 && i < 38)
 298                 return ('A' - 12 + i);
 299         if (i >= 38 && i < 63)
 300                 return ('a' - 38 + i);
 301         return ('z');
 302 }
 303
 304 static char *crypt_make_salt(void)
 305 {
 306         time_t now;
 307         static unsigned long x;
 308         static char result[3];
 309
 310         time(&now);
 311         x += now + getpid() + clock();
 312         result[0] = i64c(((x >> 18) ^ (x >> 6)) & 077);
 313         result[1] = i64c(((x >> 12) ^ x) & 077);
 314         result[2] = '\0';
 315         return result;
 316 }
 317
 318
 319 static int new_password(const struct passwd *pw, int amroot, int algo)
 320 {
 321         char *clear;
 322         char *cipher;
 323         char *cp;
 324         char orig[200];
 325         char pass[200];
 326         time_t start, now;
 327
 328         if (!amroot && crypt_passwd[0]) {
 329                 if (!(clear = bb_askpass(0, "Old password:"))) {
 330                         /* return -1; */
 331                         return 1;
 332                 }
 333                 cipher = pw_encrypt(clear, crypt_passwd);
 334                 if (strcmp(cipher, crypt_passwd) != 0) {
 335                         syslog(LOG_WARNING, "incorrect password for `%s'",
 336                                    pw->pw_name);
 337                         time(&start);
 338                         now = start;
 339                         while (difftime(now, start) < FAIL_DELAY) {
 340                                 sleep(FAIL_DELAY);
 341                                 time(&now);
 342                         }
 343                         fprintf(stderr, "Incorrect password.\n");
 344                         /* return -1; */
 345                         return 1;
 346                 }
 347                 safe_strncpy(orig, clear, sizeof(orig));
 348                 bzero(clear, strlen(clear));
 349                 bzero(cipher, strlen(cipher));
 350         } else {
 351                 orig[0] = '\0';
 352         }
 353         if (! (cp=bb_askpass(0, "Enter the new password (minimum of 5, maximum of 8 characters)\n"
 354                                           "Please use a combination of upper and lower case letters and numbers.\n"
 355                                           "Enter new password: ")))
 356         {
 357                 bzero(orig, sizeof orig);
 358                 /* return -1; */
 359                 return 1;
 360         }
 361         safe_strncpy(pass, cp, sizeof(pass));
 362         bzero(cp, strlen(cp));
 363         /* if (!obscure(orig, pass, pw)) { */
 364         if (obscure(orig, pass, pw)) {
 365                 if (amroot) {
 366                         printf("\nWarning: weak password (continuing).\n");
 367                 } else {
 368                         /* return -1; */
 369                         return 1;
 370                 }
 371         }
 372         if (!(cp = bb_askpass(0, "Re-enter new password: "))) {
 373                 bzero(orig, sizeof orig);
 374                 /* return -1; */
 375                 return 1;
 376         }
 377         if (strcmp(cp, pass)) {
 378                 fprintf(stderr, "Passwords do not match.\n");
 379                 /* return -1; */
 380                 return 1;
 381         }
 382         bzero(cp, strlen(cp));
 383         bzero(orig, sizeof(orig));
 384
 385         if (algo == 1) {
 386                 cp = pw_encrypt(pass, "$1$");
 387         } else
 388                 cp = pw_encrypt(pass, crypt_make_salt());
 389         bzero(pass, sizeof pass);
 390         safe_strncpy(crypt_passwd, cp, sizeof(crypt_passwd));
 391         return 0;
 392 }
 393
 394 static void set_filesize_limit(int blocks)
 395 {
 396         struct rlimit rlimit_fsize;
 397
 398         rlimit_fsize.rlim_cur = rlimit_fsize.rlim_max = 512L * blocks;
 399         setrlimit(RLIMIT_FSIZE, &rlimit_fsize);
 400 }