su: move restricted_shell into su.c (the only user)
[oweals/busybox.git] / loginutils / passwd.c
index 2811ab72eaec10b4c1cc65b7e9960fd14744c269..b447af2f5c39f73b4a324f7f03347774603edabe 100644 (file)
 /*
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  */
-
-#include "busybox.h"
+#include "libbb.h"
 #include <syslog.h>
 
-static char crypt_passwd[128];
-
-static int create_backup(const char *backup, FILE * fp);
-static int new_password(const struct passwd *pw, int amroot, int algo);
-static void set_filesize_limit(int blocks);
-
-
-static int get_algo(char *a)
+static void nuke_str(char *str)
 {
-       int x = 1;                                      /* standard: MD5 */
-
-       if (strcasecmp(a, "des") == 0)
-               x = 0;
-       return x;
+       if (str) memset(str, 0, strlen(str));
 }
 
-
-static int update_passwd(const struct passwd *pw, const char *crypt_pw)
+static char* new_password(const struct passwd *pw, uid_t myuid, int algo)
 {
-       char filename[1024];
-       char buf[1025];
-       char buffer[80];
-       char username[32];
-       char *pw_rest;
-       int mask;
-       int continued;
-       FILE *fp;
-       FILE *out_fp;
-       struct stat sb;
-       struct flock lock;
-
-#if ENABLE_FEATURE_SHADOWPASSWDS
-       if (access(bb_path_shadow_file, F_OK) == 0) {
-               snprintf(filename, sizeof filename, "%s", bb_path_shadow_file);
-       } else
-#endif
-       {
-               snprintf(filename, sizeof filename, "%s", bb_path_passwd_file);
-       }
-
-       fp = fopen(filename, "r+");
-       if (fp == 0 || fstat(fileno(fp), &sb)) {
-               /* return 0; */
-               return 1;
-       }
-
-       /* Lock the password file before updating */
-       lock.l_type = F_WRLCK;
-       lock.l_whence = SEEK_SET;
-       lock.l_start = 0;
-       lock.l_len = 0;
-       if (fcntl(fileno(fp), F_SETLK, &lock) < 0) {
-               bb_perror_msg("%s", filename);
-               return 1;
-       }
-       lock.l_type = F_UNLCK;
-
-       snprintf(buf, sizeof buf, "%s-", filename);
-       if (create_backup(buf, fp)) {
-               fcntl(fileno(fp), F_SETLK, &lock);
-               fclose(fp);
-               return 1;
-       }
-       snprintf(buf, sizeof buf, "%s+", filename);
-       mask = umask(0777);
-       out_fp = fopen(buf, "w");
-       umask(mask);
-       if ((!out_fp) || (fchmod(fileno(out_fp), sb.st_mode & 0777))
-               || (fchown(fileno(out_fp), sb.st_uid, sb.st_gid))) {
-               fcntl(fileno(fp), F_SETLK, &lock);
-               fclose(fp);
-               fclose(out_fp);
-               return 1;
-       }
-
-       continued = 0;
-       snprintf(username, sizeof username, "%s:", pw->pw_name);
-       rewind(fp);
-       while (!feof(fp)) {
-               fgets(buffer, sizeof buffer, fp);
-               if (!continued) { /* Check to see if we're updating this line.  */
-                       if (strncmp(username, buffer, strlen(username)) == 0) {
-                               /* we have a match. */
-                               pw_rest = strchr(buffer, ':');
-                               *pw_rest++ = '\0';
-                               pw_rest = strchr(pw_rest, ':');
-                               fprintf(out_fp, "%s:%s%s", buffer, crypt_pw, pw_rest);
-                       } else {
-                               fputs(buffer, out_fp);
-                       }
-               } else {
-                       fputs(buffer, out_fp);
-               }
-               if (buffer[strlen(buffer) - 1] == '\n') {
-                       continued = 0;
-               } else {
-                       continued = 1;
+       char salt[sizeof("$N$XXXXXXXX")]; /* "$N$XXXXXXXX" or "XX" */
+       char *orig = (char*)"";
+       char *newp = NULL;
+       char *cp = NULL;
+       char *ret = NULL; /* failure so far */
+
+       if (myuid && pw->pw_passwd[0]) {
+               char *encrypted;
+
+               orig = bb_ask_stdin("Old password: "); /* returns ptr to static */
+               if (!orig)
+                       goto err_ret;
+               encrypted = pw_encrypt(orig, pw->pw_passwd, 1); /* returns malloced str */
+               if (strcmp(encrypted, pw->pw_passwd) != 0) {
+                       syslog(LOG_WARNING, "incorrect password for %s",
+                               pw->pw_name);
+                       bb_do_delay(FAIL_DELAY);
+                       puts("Incorrect password");
+                       goto err_ret;
                }
-               memset(buffer, 0, sizeof buffer);
-       }
-
-       if (fflush(out_fp) || fsync(fileno(out_fp)) || fclose(out_fp)) {
-               unlink(buf);
-               fcntl(fileno(fp), F_SETLK, &lock);
-               fclose(fp);
-               return 1;
-       }
-       if (rename(buf, filename) < 0) {
-               fcntl(fileno(fp), F_SETLK, &lock);
-               fclose(fp);
-               return 1;
-       } else {
-               fcntl(fileno(fp), F_SETLK, &lock);
-               fclose(fp);
-               return 0;
-       }
+               if (ENABLE_FEATURE_CLEAN_UP) free(encrypted);
+       }
+       orig = xstrdup(orig); /* or else bb_ask_stdin() will destroy it */
+       newp = bb_ask_stdin("New password: "); /* returns ptr to static */
+       if (!newp)
+               goto err_ret;
+       newp = xstrdup(newp); /* we are going to bb_ask_stdin() again, so save it */
+       if (ENABLE_FEATURE_PASSWD_WEAK_CHECK
+        && obscure(orig, newp, pw) && myuid)
+               goto err_ret; /* non-root is not allowed to have weak passwd */
+
+       cp = bb_ask_stdin("Retype password: ");
+       if (!cp)
+               goto err_ret;
+       if (strcmp(cp, newp)) {
+               puts("Passwords don't match");
+               goto err_ret;
+       }
+
+       crypt_make_salt(salt, 1, 0); /* des */
+       if (algo) { /* MD5 */
+               strcpy(salt, "$1$");
+               crypt_make_salt(salt + 3, 4, 0);
+       }
+       /* pw_encrypt returns malloced str */
+       ret = pw_encrypt(newp, salt, 1);
+       /* whee, success! */
+
+ err_ret:
+       nuke_str(orig);
+       if (ENABLE_FEATURE_CLEAN_UP) free(orig);
+       nuke_str(newp);
+       if (ENABLE_FEATURE_CLEAN_UP) free(newp);
+       nuke_str(cp);
+       return ret;
 }
 
-
-int passwd_main(int argc, char **argv)
+int passwd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int passwd_main(int argc UNUSED_PARAM, char **argv)
 {
        enum {
                OPT_algo = 0x1, /* -a - password algorithm */
@@ -133,244 +78,135 @@ int passwd_main(int argc, char **argv)
                OPT_unlock = 0x4, /* -u - unlock account */
                OPT_delete = 0x8, /* -d - delete password */
                OPT_lud = 0xe,
+               STATE_ALGO_md5 = 0x10,
+               //STATE_ALGO_des = 0x20, not needed yet
        };
        unsigned opt;
-       char *opt_a;
-       int amroot;
-       char *cp;
-       char *np;
-       char *name;
+       int rc;
+       const char *opt_a = "";
+       const char *filename;
        char *myname;
-       int algo = 1;
-       const struct passwd *pw;
+       char *name;
+       char *newp;
+       struct passwd *pw;
+       uid_t myuid;
+       struct rlimit rlimit_fsize;
+       char c;
+#if ENABLE_FEATURE_SHADOWPASSWDS
+       /* Using _r function to avoid pulling in static buffers */
+       struct spwd spw;
+       char buffer[256];
+#endif
 
-       amroot = (getuid() == 0);
-       openlog("passwd", LOG_PID | LOG_CONS | LOG_NOWAIT, LOG_AUTH);
-       opt = getopt32(argc, argv, "a:lud", &opt_a);
-       argc -= optind;
+       logmode = LOGMODE_BOTH;
+       openlog(applet_name, 0, LOG_AUTH);
+       opt = getopt32(argv, "a:lud", &opt_a);
+       //argc -= optind;
        argv += optind;
-       if (opt & OPT_algo) algo = get_algo(opt_a); // -a
-       if ((opt & OPT_lud) && (!argc || !amroot))
+
+       if (strcasecmp(opt_a, "des") != 0) /* -a */
+               opt |= STATE_ALGO_md5;
+       //else
+       //      opt |= STATE_ALGO_des;
+       myuid = getuid();
+       /* -l, -u, -d require root priv and username argument */
+       if ((opt & OPT_lud) && (myuid || !argv[0]))
                bb_show_usage();
 
-       myname = xstrdup(bb_getpwuid(NULL, getuid(), -1));
-       name = myname;
-       if (argc) name = argv[0];
+       /* Will complain and die if username not found */
+       myname = xstrdup(xuid2uname(myuid));
+       name = argv[0] ? argv[0] : myname;
 
-       pw = getpwnam(name);
-       if (!pw) {
-               bb_error_msg_and_die("unknown user %s", name);
+       pw = xgetpwnam(name);
+       if (myuid && pw->pw_uid != myuid) {
+               /* LOGMODE_BOTH */
+               bb_error_msg_and_die("%s can't change password for %s", myname, name);
        }
-       if (!amroot && pw->pw_uid != getuid()) {
-               syslog(LOG_WARNING, "can't change pwd for '%s'", name);
-               bb_error_msg_and_die("permission denied");
+
+#if ENABLE_FEATURE_SHADOWPASSWDS
+       {
+               /* getspnam_r may return 0 yet set result to NULL.
+                * At least glibc 2.4 does this. Be extra paranoid here. */
+               struct spwd *result = NULL;
+               errno = 0;
+               if (getspnam_r(pw->pw_name, &spw, buffer, sizeof(buffer), &result) != 0
+                || !result /* no error, but no record found either */
+                || strcmp(result->sp_namp, pw->pw_name) != 0 /* paranoia */
+               ) {
+                       if (errno != ENOENT) {
+                               /* LOGMODE_BOTH */
+                               bb_perror_msg("no record of %s in %s, using %s",
+                                       name, bb_path_shadow_file,
+                                       bb_path_passwd_file);
+                       }
+                       /* else: /etc/shadow does not exist,
+                        * apparently we are on a shadow-less system,
+                        * no surprise there */
+               } else {
+                       pw->pw_passwd = result->sp_pwdp;
+               }
        }
-       if (ENABLE_FEATURE_SHADOWPASSWDS) {
-               struct spwd *sp = getspnam(name);
-               if (!sp) bb_error_msg_and_die("unknown user %s", name);
-               cp = sp->sp_pwdp;
-       } else cp = pw->pw_passwd;
+#endif
 
-       np = name;
-       safe_strncpy(crypt_passwd, cp, sizeof(crypt_passwd));
+       /* Decide what the new password will be */
+       newp = NULL;
+       c = pw->pw_passwd[0] - '!';
        if (!(opt & OPT_lud)) {
-               if (!amroot) {
-                       if (cp[0] == '!') {
-                               syslog(LOG_WARNING, "password locked for '%s'", np);
-                               bb_error_msg_and_die("the password for %s cannot be changed", np);
-                       }
+               if (myuid && !c) { /* passwd starts with '!' */
+                       /* LOGMODE_BOTH */
+                       bb_error_msg_and_die("can't change "
+                                       "locked password for %s", name);
                }
                printf("Changing password for %s\n", name);
-               if (new_password(pw, amroot, algo)) {
-                       bb_error_msg_and_die("the password for %s is unchanged", name);
+               newp = new_password(pw, myuid, opt & STATE_ALGO_md5);
+               if (!newp) {
+                       logmode = LOGMODE_STDIO;
+                       bb_error_msg_and_die("password for %s is unchanged", name);
                }
        } else if (opt & OPT_lock) {
-               if (crypt_passwd[0] != '!') {
-                       memmove(&crypt_passwd[1], crypt_passwd,
-                                       sizeof crypt_passwd - 1);
-                       crypt_passwd[sizeof crypt_passwd - 1] = '\0';
-                       crypt_passwd[0] = '!';
-               }
+               if (!c) goto skip; /* passwd starts with '!' */
+               newp = xasprintf("!%s", pw->pw_passwd);
        } else if (opt & OPT_unlock) {
-               if (crypt_passwd[0] == '!') {
-                       memmove(crypt_passwd, &crypt_passwd[1],
-                                       sizeof crypt_passwd - 1);
-               }
+               if (c) goto skip; /* not '!' */
+               /* pw->pw_passwd points to static storage,
+                * strdup'ing to avoid nasty surprizes */
+               newp = xstrdup(&pw->pw_passwd[1]);
        } else if (opt & OPT_delete) {
-               crypt_passwd[0] = '\0';
+               //newp = xstrdup("");
+               newp = (char*)"";
        }
-       set_filesize_limit(30000);
-       signal(SIGHUP, SIG_IGN);
-       signal(SIGINT, SIG_IGN);
-       signal(SIGQUIT, SIG_IGN);
+
+       rlimit_fsize.rlim_cur = rlimit_fsize.rlim_max = 512L * 30000;
+       setrlimit(RLIMIT_FSIZE, &rlimit_fsize);
+       bb_signals(0
+               + (1 << SIGHUP)
+               + (1 << SIGINT)
+               + (1 << SIGQUIT)
+               , SIG_IGN);
        umask(077);
        xsetuid(0);
-       if (!update_passwd(pw, crypt_passwd)) {
-               syslog(LOG_INFO, "password for '%s' changed by user '%s'", name,
-                               myname);
-               puts("Password changed");
-       } else {
-               syslog(LOG_WARNING, "cannot update password file");
-               bb_error_msg_and_die("cannot update password file");
-       }
-       if (ENABLE_FEATURE_CLEAN_UP) free(myname);
-       return 0;
-}
-
-
-
-static int create_backup(const char *backup, FILE * fp)
-{
-       struct stat sb;
-       struct utimbuf ub;
-       FILE *bkfp;
-       int c, mask;
-
-       if (fstat(fileno(fp), &sb))
-               /* return -1; */
-               return 1;
-
-       mask = umask(077);
-       bkfp = fopen(backup, "w");
-       umask(mask);
-       if (!bkfp)
-               /* return -1; */
-               return 1;
-
-       /* TODO: faster copy, not one-char-at-a-time.  --marekm */
-       rewind(fp);
-       while ((c = getc(fp)) != EOF) {
-               if (putc(c, bkfp) == EOF)
-                       break;
-       }
-       if (c != EOF || fflush(bkfp)) {
-               fclose(bkfp);
-               /* return -1; */
-               return 1;
-       }
-       if (fclose(bkfp))
-               /* return -1; */
-               return 1;
 
-       ub.actime = sb.st_atime;
-       ub.modtime = sb.st_mtime;
-       utime(backup, &ub);
-       return 0;
-}
-
-static int i64c(int i)
-{
-       if (i <= 0)
-               return '.';
-       if (i == 1)
-               return '/';
-       if (i >= 2 && i < 12)
-               return ('0' - 2 + i);
-       if (i >= 12 && i < 38)
-               return ('A' - 12 + i);
-       if (i >= 38 && i < 63)
-               return ('a' - 38 + i);
-       return 'z';
-}
-
-static char *crypt_make_salt(void)
-{
-       time_t now;
-       static unsigned long x;
-       static char result[3];
-
-       time(&now);
-       x += now + getpid() + clock();
-       result[0] = i64c(((x >> 18) ^ (x >> 6)) & 077);
-       result[1] = i64c(((x >> 12) ^ x) & 077);
-       result[2] = '\0';
-       return result;
-}
-
-
-static int new_password(const struct passwd *pw, int amroot, int algo)
-{
-       char *clear;
-       char *cipher;
-       char *cp;
-       char salt[12]; /* "$N$XXXXXXXX" or "XX" */
-       char orig[200];
-       char pass[200];
-
-       if (!amroot && crypt_passwd[0]) {
-               clear = bb_askpass(0, "Old password:");
-               if (!clear) {
-                       /* return -1; */
-                       return 1;
-               }
-               cipher = pw_encrypt(clear, crypt_passwd);
-               if (strcmp(cipher, crypt_passwd) != 0) {
-                       syslog(LOG_WARNING, "incorrect password for '%s'",
-                                  pw->pw_name);
-                       bb_do_delay(FAIL_DELAY);
-                       puts("Incorrect password");
-                       /* return -1; */
-                       return 1;
-               }
-               safe_strncpy(orig, clear, sizeof(orig));
-               memset(clear, 0, strlen(clear));
-               memset(cipher, 0, strlen(cipher));
-       } else {
-               orig[0] = '\0';
-       }
-       cp = bb_askpass(0, "Enter the new password (minimum of 5 characters).\n"
-                          "Please use a combination of upper and lower case letters and numbers.\n"
-                          "Enter new password: ");
-       if (!cp ) {
-               memset(orig, 0, sizeof orig);
-               /* return -1; */
-               return 1;
-       }
-       safe_strncpy(pass, cp, sizeof(pass));
-       memset(cp, 0, strlen(cp));
-       /* if (!obscure(orig, pass, pw)) { */
-       if (obscure(orig, pass, pw)) {
-               if (amroot) {
-                       puts("\nWarning: weak password (continuing)");
-               } else {
-                       /* return -1; */
-                       return 1;
-               }
-       }
-       cp = bb_askpass(0, "Re-enter new password: ");
-       if (!cp) {
-               memset(orig, 0, sizeof orig);
-               /* return -1; */
-               return 1;
-       }
-       if (strcmp(cp, pass)) {
-               puts("Passwords do not match");
-               /* return -1; */
-               return 1;
+#if ENABLE_FEATURE_SHADOWPASSWDS
+       filename = bb_path_shadow_file;
+       rc = update_passwd(bb_path_shadow_file, name, newp, NULL);
+       if (rc == 0) /* no lines updated, no errors detected */
+#endif
+       {
+               filename = bb_path_passwd_file;
+               rc = update_passwd(bb_path_passwd_file, name, newp, NULL);
        }
-       memset(cp, 0, strlen(cp));
-       memset(orig, 0, sizeof(orig));
-       memset(salt, 0, sizeof(salt));
+       /* LOGMODE_BOTH */
+       if (rc < 0)
+               bb_error_msg_and_die("can't update password file %s",
+                               filename);
+       bb_info_msg("Password for %s changed by %s", name, myname);
 
-       if (algo == 1) {
-               strcpy(salt, "$1$");
-               strcat(salt, crypt_make_salt());
-               strcat(salt, crypt_make_salt());
-               strcat(salt, crypt_make_salt());
+       //if (ENABLE_FEATURE_CLEAN_UP) free(newp);
+ skip:
+       if (!newp) {
+               bb_error_msg_and_die("password for %s is already %slocked",
+                       name, (opt & OPT_unlock) ? "un" : "");
        }
-
-       strcat(salt, crypt_make_salt());
-       cp = pw_encrypt(pass, salt);
-
-       memset(pass, 0, sizeof pass);
-       safe_strncpy(crypt_passwd, cp, sizeof(crypt_passwd));
+       if (ENABLE_FEATURE_CLEAN_UP) free(myname);
        return 0;
 }
-
-static void set_filesize_limit(int blocks)
-{
-       struct rlimit rlimit_fsize;
-
-       rlimit_fsize.rlim_cur = rlimit_fsize.rlim_max = 512L * blocks;
-       setrlimit(RLIMIT_FSIZE, &rlimit_fsize);
-}