source: MondoRescue/branches/stable/mindi-busybox/loginutils/passwd.c

/* vi: set sw=4 ts=4: */
/*
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include "libbb.h"
#include <syslog.h>


static void nuke_str(char *str)
{
    if (str) memset(str, 0, strlen(str));
}

static char* new_password(const struct passwd *pw, uid_t myuid, int algo)
{
    char salt[sizeof("$N$XXXXXXXX")]; /* "$N$XXXXXXXX" or "XX" */
    char *orig = (char*)"";
    char *newp = NULL;
    char *cipher = NULL;
    char *cp = NULL;
    char *ret = NULL; /* failure so far */

    if (myuid && pw->pw_passwd[0]) {
        orig = bb_askpass(0, "Old password:"); /* returns ptr to static */
        if (!orig)
            goto err_ret;
        cipher = pw_encrypt(orig, pw->pw_passwd); /* returns ptr to static */
        if (strcmp(cipher, 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;
        }
    }
    orig = xstrdup(orig); /* or else bb_askpass() will destroy it */
    newp = bb_askpass(0, "New password:"); /* returns ptr to static */
    if (!newp)
        goto err_ret;
    newp = xstrdup(newp); /* we are going to bb_askpass() 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_askpass(0, "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 ptr to static */
    ret = xstrdup(pw_encrypt(newp, salt));
    /* 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(cipher);
    nuke_str(cp);
    return ret;
}

int passwd_main(int argc, char **argv);
int passwd_main(int argc, char **argv)
{
    enum {
        OPT_algo = 0x1, /* -a - password algorithm */
        OPT_lock = 0x2, /* -l - lock account */
        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;
    int rc;
    const char *opt_a = "";
    const char *filename;
    char *myname;
    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;
    struct spwd *result;
    char buffer[256];
#endif

    logmode = LOGMODE_BOTH;
    openlog(applet_name, LOG_NOWAIT, LOG_AUTH);
    opt = getopt32(argv, "a:lud", &opt_a);
    //argc -= optind;
    argv += optind;

    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();

    /* Will complain and die if username not found */
    myname = xstrdup(bb_getpwuid(NULL, -1, myuid));
    name = argv[0] ? argv[0] : myname;

    pw = getpwnam(name);
    if (!pw) bb_error_msg_and_die("unknown user %s", name);
    if (myuid && pw->pw_uid != myuid) {
        /* LOGMODE_BOTH */
        bb_error_msg_and_die("%s can't change password for %s", myname, name);
    }

#if ENABLE_FEATURE_SHADOWPASSWDS
    /* getspnam_r() can lie! Even if user isn't in shadow, it can
     * return success (pwd field was seen set to "!" in this case) */
    if (getspnam_r(pw->pw_name, &spw, buffer, sizeof(buffer), &result)
     || LONE_CHAR(spw.sp_pwdp, '!')) {
        /* LOGMODE_BOTH */
        bb_error_msg("no record of %s in %s, using %s",
                name, bb_path_shadow_file,
                bb_path_passwd_file);
    } else {
        pw->pw_passwd = spw.sp_pwdp;
    }
#endif

    /* Decide what the new password will be */
    newp = NULL;
    c = pw->pw_passwd[0] - '!';
    if (!(opt & OPT_lud)) {
        if (myuid && !c) { /* passwd starts with '!' */
            /* LOGMODE_BOTH */
            bb_error_msg_and_die("cannot change "
                    "locked password for %s", name);
        }
        printf("Changing password for %s\n", 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 (!c) goto skip; /* passwd starts with '!' */
        newp = xasprintf("!%s", pw->pw_passwd);
    } else if (opt & OPT_unlock) {
        if (c) goto skip; /* not '!' */
        /* pw->pw_passwd pints to static storage,
         * strdup'ing to avoid nasty surprizes */
        newp = xstrdup(&pw->pw_passwd[1]);
    } else if (opt & OPT_delete) {
        //newp = xstrdup("");
        newp = (char*)"";
    }

    rlimit_fsize.rlim_cur = rlimit_fsize.rlim_max = 512L * 30000;
    setrlimit(RLIMIT_FSIZE, &rlimit_fsize);
    signal(SIGHUP, SIG_IGN);
    signal(SIGINT, SIG_IGN);
    signal(SIGQUIT, SIG_IGN);
    umask(077);
    xsetuid(0);

#if ENABLE_FEATURE_SHADOWPASSWDS
    filename = bb_path_shadow_file;
    rc = update_passwd(bb_path_shadow_file, name, newp);
    if (rc == 0) /* no lines updated, no errors detected */
#endif
    {
        filename = bb_path_passwd_file;
        rc = update_passwd(bb_path_passwd_file, name, newp);
    }
    /* LOGMODE_BOTH */
    if (rc < 0)
        bb_error_msg_and_die("cannot update password file %s",
                filename);
    bb_info_msg("Password for %s changed by %s", name, myname);

    //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" : "");
    }
    if (ENABLE_FEATURE_CLEAN_UP) free(myname);
    return 0;
}