login.c

Util-linux 软件包包含许多工具。其中比较重要的是加载、卸载、格式化、分区和管理硬盘驱动器

	tty_name = ttyn;

    if (strncmp(ttyn, "/dev/tty", 8) == 0)
	tty_number = ttyn+8;
    else {
	char *p = ttyn;
	while (*p && !isdigit(*p)) p++;
	tty_number = p;
    }

#ifdef CHOWNVCS
    /* find names of Virtual Console devices, for later mode change */
    snprintf(vcsn, sizeof(vcsn), "/dev/vcs%s", tty_number);
    snprintf(vcsan, sizeof(vcsan), "/dev/vcsa%s", tty_number);
#endif

    /* set pgid to pid */
    setpgrp();
    /* this means that setsid() will fail */
    
    {
	struct termios tt, ttt;
	
	tcgetattr(0, &tt);
	ttt = tt;
	ttt.c_cflag &= ~HUPCL;

	/* These can fail, e.g. with ttyn on a read-only filesystem */
	chown(ttyn, 0, 0);
	chmod(ttyn, TTY_MODE);

	/* Kill processes left on this tty */
	tcsetattr(0,TCSAFLUSH,&ttt);
	signal(SIGHUP, SIG_IGN); /* so vhangup() wont kill us */
	vhangup();
	signal(SIGHUP, SIG_DFL);

	/* open stdin,stdout,stderr to the tty */
	opentty(ttyn);
	
	/* restore tty modes */
	tcsetattr(0,TCSAFLUSH,&tt);
    }

    openlog("login", LOG_ODELAY, LOG_AUTHPRIV);

#if 0
    /* other than iso-8859-1 */
    printf("\033(K");
    fprintf(stderr,"\033(K");
#endif

#ifdef USE_PAM
    /*
     * username is initialized to NULL
     * and if specified on the command line it is set.
     * Therefore, we are safe not setting it to anything
     */

    retcode = pam_start("login",username, &conv, &pamh);
    if(retcode != PAM_SUCCESS) {
	fprintf(stderr, _("login: PAM Failure, aborting: %s\n"),
		pam_strerror(pamh, retcode));
	syslog(LOG_ERR, _("Couldn't initialize PAM: %s"),
	       pam_strerror(pamh, retcode));
	exit(99);
    }
    /* hostname & tty are either set to NULL or their correct values,
       depending on how much we know */
    retcode = pam_set_item(pamh, PAM_RHOST, hostname);
    PAM_FAIL_CHECK;
    retcode = pam_set_item(pamh, PAM_TTY, tty_name);
    PAM_FAIL_CHECK;

    /*
     * [e-mail]: Provide a user prompt to PAM
     * so that the "login: " prompt gets localized. Unfortunately,
     * PAM doesn't have an interface to specify the "Password: " string
     * (yet).
     */
    retcode = pam_set_item(pamh, PAM_USER_PROMPT, _("login: "));
    PAM_FAIL_CHECK;

#if 0
    /*
     * other than iso-8859-1
     * one more time due to reset tty by PAM
     */
    printf("\033(K");
    fprintf(stderr,"\033(K");
#endif
	    
    /* if fflag == 1, then the user has already been authenticated */
    if (fflag && (getuid() == 0))
	passwd_req = 0;
    else
	passwd_req = 1;

    if(passwd_req == 1) {
	int failcount=0;

	/* if we didn't get a user on the command line, set it to NULL */
	pam_get_item(pamh,  PAM_USER, (const void **) &username);
	if (!username)
		pam_set_item(pamh, PAM_USER, NULL);

	/* there may be better ways to deal with some of these
	   conditions, but at least this way I don't think we'll
	   be giving away information... */
	/* Perhaps someday we can trust that all PAM modules will
	   pay attention to failure count and get rid of MAX_LOGIN_TRIES? */

	retcode = pam_authenticate(pamh, 0);
	while((failcount++ < PAM_MAX_LOGIN_TRIES) &&
	      ((retcode == PAM_AUTH_ERR) ||
	       (retcode == PAM_USER_UNKNOWN) ||
	       (retcode == PAM_CRED_INSUFFICIENT) ||
	       (retcode == PAM_AUTHINFO_UNAVAIL))) {
	    pam_get_item(pamh, PAM_USER, (const void **) &username);

	    syslog(LOG_NOTICE,_("FAILED LOGIN %d FROM %s FOR %s, %s"),
		   failcount, hostname, username, pam_strerror(pamh, retcode));
	    logbtmp(tty_name, username, hostname);

	    fprintf(stderr,_("Login incorrect\n\n"));
	    pam_set_item(pamh,PAM_USER,NULL);
	    retcode = pam_authenticate(pamh, 0);
	}

	if (retcode != PAM_SUCCESS) {
	    pam_get_item(pamh, PAM_USER, (const void **) &username);

	    if (retcode == PAM_MAXTRIES)
		syslog(LOG_NOTICE,_("TOO MANY LOGIN TRIES (%d) FROM %s FOR "
			"%s, %s"), failcount, hostname, username,
			 pam_strerror(pamh, retcode));
	    else
		syslog(LOG_NOTICE,_("FAILED LOGIN SESSION FROM %s FOR %s, %s"),
			hostname, username, pam_strerror(pamh, retcode));
	    logbtmp(tty_name, username, hostname);

	    fprintf(stderr,_("\nLogin incorrect\n"));
	    pam_end(pamh, retcode);
	    exit(0);
	}

	retcode = pam_acct_mgmt(pamh, 0);

	if(retcode == PAM_NEW_AUTHTOK_REQD) {
	    retcode = pam_chauthtok(pamh, PAM_CHANGE_EXPIRED_AUTHTOK);
	}

	PAM_FAIL_CHECK;
    }

    /*
     * Grab the user information out of the password file for future usage
     * First get the username that we are actually using, though.
     */
    retcode = pam_get_item(pamh, PAM_USER, (const void **) &username);
    PAM_FAIL_CHECK;

    if (!username || !*username) {
	    fprintf(stderr, _("\nSession setup problem, abort.\n"));
	    syslog(LOG_ERR, _("NULL user name in %s:%d. Abort."),
		   __FUNCTION__, __LINE__);
	    pam_end(pamh, PAM_SYSTEM_ERR);
	    exit(1);
    }
    if (!(pwd = getpwnam(username))) {
	    fprintf(stderr, _("\nSession setup problem, abort.\n"));
	    syslog(LOG_ERR, _("Invalid user name \"%s\" in %s:%d. Abort."),
		   username, __FUNCTION__, __LINE__);
	    pam_end(pamh, PAM_SYSTEM_ERR);
	    exit(1);
    }

    /*
     * Create a copy of the pwd struct - otherwise it may get
     * clobbered by PAM
     */
    memcpy(&pwdcopy, pwd, sizeof(*pwd));
    pwd = &pwdcopy;
    pwd->pw_name   = strdup(pwd->pw_name);
    pwd->pw_passwd = strdup(pwd->pw_passwd);
    pwd->pw_gecos  = strdup(pwd->pw_gecos);
    pwd->pw_dir    = strdup(pwd->pw_dir);
    pwd->pw_shell  = strdup(pwd->pw_shell);
    if (!pwd->pw_name || !pwd->pw_passwd || !pwd->pw_gecos ||
	!pwd->pw_dir || !pwd->pw_shell) {
	    fprintf(stderr, _("login: Out of memory\n"));
	    syslog(LOG_ERR, "Out of memory");
	    pam_end(pamh, PAM_SYSTEM_ERR);
	    exit(1);
    }
    username = pwd->pw_name;

    /*
     * Initialize the supplementary group list.
     * This should be done before pam_setcred because
     * the PAM modules might add groups during pam_setcred.
     */
    if (initgroups(username, pwd->pw_gid) < 0) {
	    syslog(LOG_ERR, "initgroups: %m");
	    fprintf(stderr, _("\nSession setup problem, abort.\n"));
	    pam_end(pamh, PAM_SYSTEM_ERR);
	    exit(1);
    }

    retcode = pam_open_session(pamh, 0);
    PAM_FAIL_CHECK;

    retcode = pam_setcred(pamh, PAM_ESTABLISH_CRED);
    PAM_FAIL_CHECK;

#else /* ! USE_PAM */

    for (cnt = 0;; ask = 1) {

	if (ask) {
	    fflag = 0;
	    getloginname();
	}

	/* Dirty patch to fix a gigantic security hole when using 
	   yellow pages. This problem should be solved by the
	   libraries, and not by programs, but this must be fixed
	   urgently! If the first char of the username is '+', we 
	   avoid login success.
	   Feb 95 <[e-mail]> */
	
	if (username[0] == '+') {
	    puts(_("Illegal username"));
	    badlogin(username);
	    sleepexit(1);
	}
	
	/* (void)strcpy(tbuf, username); why was this here? */
	if ((pwd = getpwnam(username))) {
#  ifdef SHADOW_PWD
	    struct spwd *sp;
	    
	    if ((sp = getspnam(username)))
	      pwd->pw_passwd = sp->sp_pwdp;
#  endif
	    salt = pwd->pw_passwd;
	} else
	  salt = "xx";
	
	if (pwd) {
	    initgroups(username, pwd->pw_gid);
	    checktty(username, tty_name, pwd); /* in checktty.c */
	}
	
	/* if user not super-user, check for disabled logins */
	if (pwd == NULL || pwd->pw_uid)
	  checknologin();
	
	/*
	 * Disallow automatic login to root; if not invoked by
	 * root, disallow if the uid's differ.
	 */
	if (fflag && pwd) {
	    int uid = getuid();
	    
	    passwd_req = pwd->pw_uid == 0 ||
	      (uid && uid != pwd->pw_uid);
	}
	
	/*
	 * If trying to log in as root, but with insecure terminal,
	 * refuse the login attempt.
	 */
	if (pwd && pwd->pw_uid == 0 && !rootterm(tty_name)) {
	    fprintf(stderr,
		    _("%s login refused on this terminal.\n"),
		    pwd->pw_name);
	    
	    if (hostname)
	      syslog(LOG_NOTICE,
		     _("LOGIN %s REFUSED FROM %s ON TTY %s"),
		     pwd->pw_name, hostname, tty_name);
	    else
	      syslog(LOG_NOTICE,
		     _("LOGIN %s REFUSED ON TTY %s"),
		     pwd->pw_name, tty_name);
	    continue;
	}

	/*
	 * If no pre-authentication and a password exists
	 * for this user, prompt for one and verify it.
	 */
	if (!passwd_req || (pwd && !*pwd->pw_passwd))
	  break;
	
	setpriority(PRIO_PROCESS, 0, -4);
	pp = getpass(_("Password: "));
	
#  ifdef CRYPTOCARD
	if (strncmp(pp, "CRYPTO", 6) == 0) {
	    if (pwd && cryptocard()) break;
	}
#  endif /* CRYPTOCARD */
	
	p = crypt(pp, salt);
	setpriority(PRIO_PROCESS, 0, 0);

#  ifdef KERBEROS
	/*
	 * If not present in pw file, act as we normally would.
	 * If we aren't Kerberos-authenticated, try the normal
	 * pw file for a password.  If that's ok, log the user
	 * in without issueing any tickets.
	 */
	
	if (pwd && !krb_get_lrealm(realm,1)) {
	    /*
	     * get TGT for local realm; be careful about uid's
	     * here for ticket file ownership
	     */
	    setreuid(geteuid(),pwd->pw_uid);
	    kerror = krb_get_pw_in_tkt(pwd->pw_name, "", realm,
				       "krbtgt", realm, DEFAULT_TKT_LIFE, pp);
	    setuid(0);
	    if (kerror == INTK_OK) {
		memset(pp, 0, strlen(pp));
		notickets = 0;	/* user got ticket */
		break;
	    }
	}
#  endif /* KERBEROS */
	memset(pp, 0, strlen(pp));

	if (pwd && !strcmp(p, pwd->pw_passwd))
	  break;
	
	printf(_("Login incorrect\n"));
	badlogin(username); /* log ALL bad logins */
	failures++;
	
	/* we allow 10 tries, but after 3 we start backing off */
	if (++cnt > 3) {
	    if (cnt >= 10) {
		sleepexit(1);
	    }
	    sleep((unsigned int)((cnt - 3) * 5));
	}
    }
#endif /* !USE_PAM */
    
    /* committed to login -- turn off timeout */
    alarm((unsigned int)0);
    
#ifdef HAVE_QUOTA
    if (quota(Q_SETUID, pwd->pw_uid, 0, 0) < 0 && errno != EINVAL) {
	switch(errno) {
	  case EUSERS:
	    fprintf(stderr,
		    _("Too many users logged on already.\nTry again later.\n"));
	    break;
	  case EPROCLIM:
	    fprintf(stderr,
		    _("You have too many processes running.\n"));
	    break;
	  default:
	    perror("quota (Q_SETUID)");
	}
	sleepexit(0);		/* %% */
    }
#endif
    
    /* paranoia... */
#ifdef SHADOW_PWD
    endspent();
#endif
    endpwent();
    
    /* This requires some explanation: As root we may not be able to
       read the directory of the user if it is on an NFS mounted
       filesystem. We temporarily set our effective uid to the user-uid
       making sure that we keep root privs. in the real uid. 
       
       A portable solution would require a fork(), but we rely on Linux
       having the BSD setreuid() */
    
    {
	char tmpstr[MAXPATHLEN];
	uid_t ruid = getuid();
	gid_t egid = getegid();

	/* avoid snprintf - old systems do not have it, or worse,
	   have a libc in which snprintf is the same as sprintf */
	if (strlen(pwd->pw_dir) + sizeof(_PATH_HUSHLOGIN) + 2 > MAXPATHLEN)
		quietlog = 0;
	else {
		sprintf(tmpstr, "%s/%s", pwd->pw_dir, _PATH_HUSHLOGIN);
		setregid(-1, pwd->pw_gid);
		setreuid(0, pwd->pw_uid);
		quietlog = (access(tmpstr, R_OK) == 0);
		setuid(0); /* setreuid doesn't do it alone! */
		setreuid(ruid, 0);
		setregid(-1, egid);
	}
    }
    
    /* for linux, write entries in utmp and wtmp */
    {
	struct utmp ut;
	struct utmp *utp;
	
	utmpname(_PATH_UTMP);
	setutent();

	/* Find pid in utmp.
login sometimes overwrites the runlevel entry in /var/run/utmp,
confusing sysvinit. I added a test for the entry type, and the problem
was gone. (In a runlevel entry, st_pid is not really a pid but some number
calculated from the previous and current runlevel).
Michael Riepe <[e-mail]>
	*/
	while ((utp = getutent()))
		if (utp->ut_pid == pid
		    && utp->ut_type >= INIT_PROCESS
		    && utp->ut_type <= DEAD_PROCESS)
			break;

	/* If we can't find a pre-existing entry by pid, try by line.
	   BSD network daemons may rely on this. (anonymous) */
	if (utp == NULL) {
	     setutent();
	     ut.ut_type = LOGIN_PROCESS;
	     strncpy(ut.ut_line, tty_name, sizeof(ut.ut_line));
	     utp = getutline(&ut);
	}
	
	if (utp) {
	    memcpy(&ut, utp, sizeof(ut));
	} else {
	    /* some gettys/telnetds don't initialize utmp... */
	    memset(&ut, 0, sizeof(ut));
	}
	
	if (ut.ut_id[0] == 0)
	  strncpy(ut.ut_id, tty_number, sizeof(ut.ut_id));
	
	strncpy(ut.ut_user, username, sizeof(ut.ut_user));
	xstrncpy(ut.ut_line, tty_name, sizeof(ut.ut_line));
#ifdef _HAVE_UT_TV		/* in <utmpbits.h> included by <utmp.h> */
	gettimeofday(&ut.ut_tv, NULL);
#else
	{
	    time_t t;
	    time(&t);
	    ut.ut_time = t;	/* ut_time is not always a time_t */
				/* glibc2 #defines it as ut_tv.tv_sec */
	}
#endif
	ut.ut_type = USER_PROCESS;
	ut.ut_pid = pid;
	if (hostname) {
		xstrncpy(ut.ut_host, hostname, sizeof(ut.ut_host));
		if (hostaddress[0])
			memcpy(&ut.ut_addr, hostaddress, sizeof(ut.ut_addr));
	}
	
	pututline(&ut);
	endutent();

#ifdef HAVE_updwtmp
	updwtmp(_PATH_WTMP, &ut);
#else
#if 0
	/* The O_APPEND open() flag should be enough to guarantee
	   atomic writes at end of file. */
	{