source: MondoRescue/branches/3.3/mindi-busybox/loginutils/passwd.c@ 3621

/* vi: set sw=4 ts=4: */
/*
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
//config:config PASSWD
//config:   bool "passwd"
//config:   default y
//config:   select FEATURE_SYSLOG
//config:   help
//config:     passwd changes passwords for user and group accounts. A normal user
//config:     may only change the password for his/her own account, the super user
//config:     may change the password for any account. The administrator of a group
//config:     may change the password for the group.
//config:
//config:     Note that Busybox binary must be setuid root for this applet to
//config:     work properly.
//config:
//config:config FEATURE_PASSWD_WEAK_CHECK
//config:   bool "Check new passwords for weakness"
//config:   default y
//config:   depends on PASSWD
//config:   help
//config:     With this option passwd will refuse new passwords which are "weak".

//applet:/* Needs to be run by root or be suid root - needs to change /etc/{passwd,shadow}: */
//applet:IF_PASSWD(APPLET(passwd, BB_DIR_USR_BIN, BB_SUID_REQUIRE))

//kbuild:lib-$(CONFIG_PASSWD) += passwd.o

//usage:#define passwd_trivial_usage
//usage:       "[OPTIONS] [USER]"
//usage:#define passwd_full_usage "\n\n"
//usage:       "Change USER's password (default: current user)"
//usage:     "\n"
//usage:     "\n    -a ALG  Encryption method"
//usage:     "\n    -d  Set password to ''"
//usage:     "\n    -l  Lock (disable) account"
//usage:     "\n    -u  Unlock (enable) account"

#include "libbb.h"
#include <syslog.h>
#include <sys/resource.h> /* setrlimit */

static char* new_password(const struct passwd *pw, uid_t myuid, const char *algo)
{
    char salt[MAX_PW_SALT_LEN];
    char *orig = (char*)"";
    char *newp = NULL;
    char *cp = NULL;
    char *ret = NULL; /* failure so far */

    if (myuid != 0 && 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(LOGIN_FAIL_DELAY);
            puts("Incorrect password");
            goto err_ret;
        }
        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 != 0
    ) {
        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) != 0) {
        puts("Passwords don't match");
        goto err_ret;
    }

    crypt_make_pw_salt(salt, algo);

    /* 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) MAIN_EXTERNALLY_VISIBLE;
int passwd_main(int argc UNUSED_PARAM, char **argv)
{
    enum {
        OPT_algo   = (1 << 0), /* -a - password algorithm */
        OPT_lock   = (1 << 1), /* -l - lock account */
        OPT_unlock = (1 << 2), /* -u - unlock account */
        OPT_delete = (1 << 3), /* -d - delete password */
        OPT_lud    = OPT_lock | OPT_unlock | OPT_delete,
    };
    unsigned opt;
    int rc;
    const char *opt_a = CONFIG_FEATURE_DEFAULT_PASSWD_ALGO;
    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;
    char buffer[256];
#endif

    logmode = LOGMODE_BOTH;
    openlog(applet_name, 0, LOG_AUTH);
    opt = getopt32(argv, "a:lud", &opt_a);
    //argc -= optind;
    argv += optind;

    myuid = getuid();
    /* -l, -u, -d require root priv and username argument */
    if ((opt & OPT_lud) && (myuid != 0 || !argv[0]))
        bb_show_usage();

    /* Will complain and die if username not found */
    myname = xstrdup(xuid2uname(myuid));
    name = argv[0] ? argv[0] : myname;

    pw = xgetpwnam(name);
    if (myuid != 0 && 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 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;
        }
    }
#endif

    /* Decide what the new password will be */
    newp = NULL;
    c = pw->pw_passwd[0] - '!';
    if (!(opt & OPT_lud)) {
        if (myuid != 0 && !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);
        newp = new_password(pw, myuid, opt_a);
        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 points to static storage,
         * strdup'ing to avoid nasty surprizes */
        newp = xstrdup(&pw->pw_passwd[1]);
    } else if (opt & OPT_delete) {
        newp = (char*)"";
    }

    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 ENABLE_FEATURE_SHADOWPASSWDS
    filename = bb_path_shadow_file;
    rc = update_passwd(bb_path_shadow_file, name, newp, NULL);
    if (rc > 0)
        /* password in /etc/shadow was updated */
        newp = (char*) "x";
    if (rc >= 0)
        /* 0 = /etc/shadow missing (not an error), >0 = passwd changed in /etc/shadow */
#endif
    {
        filename = bb_path_passwd_file;
        rc = update_passwd(bb_path_passwd_file, name, newp, NULL);
    }
    /* LOGMODE_BOTH */
    if (rc < 0)
        bb_error_msg_and_die("can't update password file %s", filename);
    bb_error_msg("password for %s changed by %s", name, myname);

    /*if (ENABLE_FEATURE_CLEAN_UP) free(newp); - can't, it may be non-malloced */
 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;
}