MFC r1.6 r1.30 r1.28 (HEAD):

[dragonfly.git] / usr.bin / login / login.c

/*-
 * Copyright (c) 1980, 1987, 1988, 1991, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * @(#)login.c  8.4 (Berkeley) 4/2/94
 * $FreeBSD: src/usr.bin/login/login.c,v 1.51.2.15 2003/04/29 14:10:41 des Exp $
 * $DragonFly: src/usr.bin/login/login.c,v 1.6 2006/01/12 13:43:11 corecode Exp $
 */

#if 0
static char copyright[] =
"@(#) Copyright (c) 1980, 1987, 1988, 1991, 1993, 1994\n\
        The Regents of the University of California.  All rights reserved.\n";
#endif

/*
 * login [ name ]
 * login -h hostname    (for telnetd, etc.)
 * login -f name        (for pre-authenticated login: datakit, xterm, etc.)
 */

#include <sys/copyright.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/file.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <err.h>
#include <errno.h>
#include <grp.h>
#include <libutil.h>
#include <login_cap.h>
#include <netdb.h>
#include <pwd.h>
#include <setjmp.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <ttyent.h>
#include <unistd.h>
#include <utmp.h>

#ifdef USE_PAM
#include <security/pam_appl.h>
#include <security/pam_types.h>
#include <security/openpam.h>
#include <sys/wait.h>
#endif /* USE_PAM */

#include "pathnames.h"

/* wrapper for KAME-special getnameinfo() */
#ifndef NI_WITHSCOPEID
#define NI_WITHSCOPEID  0
#endif

void     badlogin(char *);
void     checknologin(void);
void     dolastlog(int);
void     getloginname(void);
void     motd(char *);
int      rootterm(char *);
void     sigint(int);
void     sleepexit(int);
void     refused(char *,char *,int);
char    *stypeof(char *);
void     timedout(int);
int      login_access(char *, char *);
void     login_fbtab(char *, uid_t, gid_t);

#ifdef USE_PAM
static int auth_pam(void);
static int export_pam_environment(void);
static int ok_to_export(const char *);

static pam_handle_t *pamh = NULL;
static char **environ_pam;

#define PAM_END { \
        if ((e = pam_setcred(pamh, PAM_DELETE_CRED)) != PAM_SUCCESS) \
                syslog(LOG_ERR, "pam_setcred: %s", pam_strerror(pamh, e)); \
        if ((e = pam_close_session(pamh,0)) != PAM_SUCCESS) \
                syslog(LOG_ERR, "pam_close_session: %s", pam_strerror(pamh, e)); \
        if ((e = pam_end(pamh, e)) != PAM_SUCCESS) \
                syslog(LOG_ERR, "pam_end: %s", pam_strerror(pamh, e)); \
}
#endif /* USE_PAM */
static int auth_traditional(void);
extern void login(struct utmp *);
static void usage(void);

#define TTYGRPNAME      "tty"           /* name of group to own ttys */
#define DEFAULT_BACKOFF 3
#define DEFAULT_RETRIES 10
#define DEFAULT_PROMPT          "login: "
#define DEFAULT_PASSWD_PROMPT   "Password:"

/*
 * This bounds the time given to login.  Not a define so it can
 * be patched on machines where it's too small.
 */
u_int   timeout = 300;

/* Buffer for signal handling of timeout */
jmp_buf timeout_buf;

struct  passwd *pwd;
int     failures;
char    *term, *envinit[1], *hostname, *passwd_prompt, *prompt, *tty, *username;
char    full_hostname[MAXHOSTNAMELEN];

int
main(int argc, char **argv)
{
        extern char **environ;
        struct group *gr;
        struct stat st;
        struct timeval tp;
        struct utmp utmp;
        int rootok, retries, backoff;
        int ask, ch, cnt, fflag, hflag, pflag, quietlog, rootlogin, rval;
        int changepass;
        time_t warntime;
        uid_t uid, euid;
        gid_t egid;
        char *p, *ttyn;
        char tbuf[MAXPATHLEN + 2];
        char tname[sizeof(_PATH_TTY) + 10];
        char *shell = NULL;
        login_cap_t *lc = NULL;
#ifdef USE_PAM
        pid_t pid;
        int e;
#endif /* USE_PAM */

        (void)signal(SIGQUIT, SIG_IGN);
        (void)signal(SIGINT, SIG_IGN);
        (void)signal(SIGHUP, SIG_IGN);
        if (setjmp(timeout_buf)) {
                if (failures)
                        badlogin(tbuf);
                (void)fprintf(stderr, "Login timed out after %d seconds\n",
                    timeout);
                exit(0);
        }
        (void)signal(SIGALRM, timedout);
        (void)alarm(timeout);
        (void)setpriority(PRIO_PROCESS, 0, 0);

        openlog("login", LOG_ODELAY, LOG_AUTH);

        /*
         * -p is used by getty to tell login not to destroy the environment
         * -f is used to skip a second login authentication
         * -h is used by other servers to pass the name of the remote
         *    host to login so that it may be placed in utmp and wtmp
         */
        *full_hostname = '\0';
        term = NULL;

        fflag = hflag = pflag = 0;
        uid = getuid();
        euid = geteuid();
        egid = getegid();
        while ((ch = getopt(argc, argv, "fh:p")) != -1)
                switch (ch) {
                case 'f':
                        fflag = 1;
                        break;
                case 'h':
                        if (uid)
                                errx(1, "-h option: %s", strerror(EPERM));
                        hflag = 1;
                        if (strlcpy(full_hostname, optarg,
                            sizeof(full_hostname)) >= sizeof(full_hostname))
                                errx(1, "-h option: %s: exceeds maximum "
                                    "hostname size", optarg);

                        trimdomain(optarg, UT_HOSTSIZE);

                        if (strlen(optarg) > UT_HOSTSIZE) {
                                struct addrinfo hints, *res;
                                int ga_err;
                                
                                memset(&hints, 0, sizeof(hints));
                                hints.ai_family = AF_UNSPEC;
                                ga_err = getaddrinfo(optarg, NULL, &hints,
                                    &res);
                                if (ga_err == 0) {
                                        char hostbuf[MAXHOSTNAMELEN];

                                        getnameinfo(res->ai_addr,
                                            res->ai_addrlen,
                                            hostbuf,
                                            sizeof(hostbuf), NULL, 0,
                                            NI_NUMERICHOST|
                                            NI_WITHSCOPEID);
                                        optarg = strdup(hostbuf);
                                        if (optarg == NULL) {
                                                syslog(LOG_NOTICE,
                                                    "strdup(): %m");
                                                sleepexit(1);
                                        }
                                } else
                                        optarg = "invalid hostname";
                                if (res != NULL)
                                        freeaddrinfo(res);
                        }
                        hostname = optarg;
                        break;
                case 'p':
                        pflag = 1;
                        break;
                case '?':
                default:
                        if (!uid)
                                syslog(LOG_ERR, "invalid flag %c", ch);
                        usage();
                }
        argc -= optind;
        argv += optind;

        if (*argv) {
                username = *argv;
                ask = 0;
        } else
                ask = 1;

        setproctitle("-%s", getprogname());

        for (cnt = getdtablesize(); cnt > 2; cnt--)
                (void)close(cnt);

        ttyn = ttyname(STDIN_FILENO);
        if (ttyn == NULL || *ttyn == '\0') {
                (void)snprintf(tname, sizeof(tname), "%s??", _PATH_TTY);
                ttyn = tname;
        }
        if ((tty = strrchr(ttyn, '/')) != NULL)
                ++tty;
        else
                tty = ttyn;

        /*
         * Get "login-retries" & "login-backoff" from default class
         */
        lc = login_getclass(NULL);
        prompt = login_getcapstr(lc, "login_prompt",
            DEFAULT_PROMPT, DEFAULT_PROMPT);
        passwd_prompt = login_getcapstr(lc, "passwd_prompt",
            DEFAULT_PASSWD_PROMPT, DEFAULT_PASSWD_PROMPT);
        retries = login_getcapnum(lc, "login-retries", DEFAULT_RETRIES,
            DEFAULT_RETRIES);
        backoff = login_getcapnum(lc, "login-backoff", DEFAULT_BACKOFF,
            DEFAULT_BACKOFF);
        login_close(lc);
        lc = NULL;

        for (cnt = 0;; ask = 1) {
                if (ask) {
                        fflag = 0;
                        getloginname();
                }
                rootlogin = 0;
                rootok = rootterm(tty); /* Default (auth may change) */

                if (strlen(username) > UT_NAMESIZE)
                        username[UT_NAMESIZE] = '\0';

                /*
                 * Note if trying multiple user names; log failures for
                 * previous user name, but don't bother logging one failure
                 * for nonexistent name (mistyped username).
                 */
                if (failures && strcmp(tbuf, username)) {
                        if (failures > (pwd ? 0 : 1))
                                badlogin(tbuf);
                }
                (void)strlcpy(tbuf, username, sizeof(tbuf));

                pwd = getpwnam(username);

                /*
                 * if we have a valid account name, and it doesn't have a
                 * password, or the -f option was specified and the caller
                 * is root or the caller isn't changing their uid, don't
                 * authenticate.
                 */
                if (pwd != NULL) {
                        if (pwd->pw_uid == 0)
                                rootlogin = 1;

                        if (fflag && (uid == (uid_t)0 ||
                            uid == (uid_t)pwd->pw_uid)) {
                                /* already authenticated */
                                break;
                        } else if (pwd->pw_passwd[0] == '\0') {
                                if (!rootlogin || rootok) {
                                        /* pretend password okay */
                                        rval = 0;
                                        goto ttycheck;
                                }
                        }
                }

                fflag = 0;

                (void)setpriority(PRIO_PROCESS, 0, -4);

#ifdef USE_PAM
                /*
                 * Try to authenticate using PAM.  If a PAM system error
                 * occurs, perhaps because of a botched configuration,
                 * then fall back to using traditional Unix authentication.
                 */
                if ((rval = auth_pam()) == -1)
#endif /* USE_PAM */
                        rval = auth_traditional();

                (void)setpriority(PRIO_PROCESS, 0, 0);

#ifdef USE_PAM
                /*
                 * PAM authentication may have changed "pwd" to the
                 * entry for the template user.  Check again to see if
                 * this is a root login after all.
                 */
                if (pwd != NULL && pwd->pw_uid == 0)
                        rootlogin = 1;
#endif /* USE_PAM */

        ttycheck:
                /*
                 * If trying to log in as root without Kerberos,
                 * but with insecure terminal, refuse the login attempt.
                 */
                if (pwd && !rval) {
                        if (rootlogin && !rootok)
                                refused(NULL, "NOROOT", 0);
                        else    /* valid password & authenticated */
                                break;
                }

                (void)printf("Login incorrect\n");
                failures++;

                /*
                 * we allow up to 'retry' (10) tries,
                 * but after 'backoff' (3) we start backing off
                 */
                if (++cnt > backoff) {
                        if (cnt >= retries) {
                                badlogin(username);
                                sleepexit(1);
                        }
                        sleep((u_int)((cnt - backoff) * 5));
                }
        }

        /* committed to login -- turn off timeout */
        (void)alarm((u_int)0);
        (void)signal(SIGHUP, SIG_DFL);

        endpwent();

        /*
         * Establish the login class.
         */
        lc = login_getpwclass(pwd);

        /* if user not super-user, check for disabled logins */
        if (!rootlogin)
                auth_checknologin(lc);

        quietlog = login_getcapbool(lc, "hushlogin", 0);
        /* Switching needed for NFS with root access disabled */
        (void)setegid(pwd->pw_gid);
        (void)seteuid(rootlogin ? 0 : pwd->pw_uid);
        if (!*pwd->pw_dir || chdir(pwd->pw_dir) < 0) {
                if (login_getcapbool(lc, "requirehome", 0))
                        refused("Home directory not available", "HOMEDIR", 1);
                if (chdir("/") < 0) 
                        refused("Cannot find root directory", "ROOTDIR", 1);
                if (!quietlog || *pwd->pw_dir)
                        printf("No home directory.\nLogging in with home = \"/\".\n");
                pwd->pw_dir = "/";
        }
        (void)seteuid(euid);
        (void)setegid(egid);
        if (!quietlog)
                quietlog = access(_PATH_HUSHLOGIN, F_OK) == 0;

        if (pwd->pw_change || pwd->pw_expire)
                (void)gettimeofday(&tp, (struct timezone *)NULL);

#define DEFAULT_WARN  (2L * 7L * 86400L)  /* Two weeks */

        warntime = login_getcaptime(lc, "warnexpire", DEFAULT_WARN,
            DEFAULT_WARN);

        if (pwd->pw_expire) {
                if (tp.tv_sec >= pwd->pw_expire) {
                        refused("Sorry -- your account has expired", "EXPIRED",
                            1);
                } else if (pwd->pw_expire - tp.tv_sec < warntime && !quietlog)
                        (void)printf("Warning: your account expires on %s",
                            ctime(&pwd->pw_expire));
        }

        warntime = login_getcaptime(lc, "warnpassword", DEFAULT_WARN,
            DEFAULT_WARN);

        changepass = 0;
        if (pwd->pw_change) {
                if (tp.tv_sec >= pwd->pw_change) {
                        (void)printf("Sorry -- your password has expired.\n");
                        changepass = 1;
                        syslog(LOG_INFO, "%s Password expired - forcing change",
                            pwd->pw_name);
                } else if (pwd->pw_change - tp.tv_sec < warntime && !quietlog)
                        (void)printf("Warning: your password expires on %s",
                            ctime(&pwd->pw_change));
        }

        if (lc != NULL) {
                if (hostname) {
                        struct addrinfo hints, *res;
                        int ga_err;

                        memset(&hints, 0, sizeof(hints));
                        hints.ai_family = AF_UNSPEC;
                        ga_err = getaddrinfo(full_hostname, NULL, &hints,
                                             &res);
                        if (ga_err == 0) {
                                char hostbuf[MAXHOSTNAMELEN];

                                getnameinfo(res->ai_addr, res->ai_addrlen,
                                    hostbuf, sizeof(hostbuf), NULL, 0,
                                    NI_NUMERICHOST|NI_WITHSCOPEID);
                                if ((optarg = strdup(hostbuf)) == NULL) {
                                        syslog(LOG_NOTICE, "strdup(): %m");
                                        sleepexit(1);
                                }
                        } else
                                optarg = NULL;
                        if (res != NULL)
                                freeaddrinfo(res);
                        if (!auth_hostok(lc, full_hostname, optarg))
                                refused("Permission denied", "HOST", 1);
                }

                if (!auth_ttyok(lc, tty))
                        refused("Permission denied", "TTY", 1);

                if (!auth_timeok(lc, time(NULL)))
                        refused("Logins not available right now", "TIME", 1);
        }
        shell = login_getcapstr(lc, "shell", pwd->pw_shell, pwd->pw_shell);
        if (*pwd->pw_shell == '\0')
                pwd->pw_shell = _PATH_BSHELL;
        if (*shell == '\0')   /* Not overridden */
                shell = pwd->pw_shell;
        if ((shell = strdup(shell)) == NULL) {
                syslog(LOG_NOTICE, "strdup(): %m");
                sleepexit(1);
        }

#ifdef LOGIN_ACCESS
        if (login_access(pwd->pw_name, hostname ? full_hostname : tty) == 0)
                refused("Permission denied", "ACCESS", 1);
#endif /* LOGIN_ACCESS */

        /* Nothing else left to fail -- really log in. */
        memset((void *)&utmp, 0, sizeof(utmp));
        (void)time(&utmp.ut_time);
        (void)strncpy(utmp.ut_name, username, sizeof(utmp.ut_name));
        if (hostname)
                (void)strncpy(utmp.ut_host, hostname, sizeof(utmp.ut_host));
        (void)strncpy(utmp.ut_line, tty, sizeof(utmp.ut_line));
        login(&utmp);

        dolastlog(quietlog);

        /*
         * Set device protections, depending on what terminal the
         * user is logged in. This feature is used on Suns to give
         * console users better privacy.
         */
        login_fbtab(tty, pwd->pw_uid, pwd->pw_gid);

        /*
         * Clear flags of the tty.  None should be set, and when the
         * user sets them otherwise, this can cause the chown to fail.
         * Since it isn't clear that flags are useful on character
         * devices, we just clear them.
         */
        if (ttyn != tname && chflags(ttyn, 0) && errno != EOPNOTSUPP)
                syslog(LOG_ERR, "chflags(%s): %m", ttyn);
        if (ttyn != tname && chown(ttyn, pwd->pw_uid,
            (gr = getgrnam(TTYGRPNAME)) ? gr->gr_gid : pwd->pw_gid))
                syslog(LOG_ERR, "chmod(%s): %m", ttyn);


        /*
         * Preserve TERM if it happens to be already set.
         */
        if ((term = getenv("TERM")) != NULL) {
                if ((term = strdup(term)) == NULL) {
                        syslog(LOG_NOTICE,
                            "strdup(): %m");
                        sleepexit(1);
                }
        }

        /*
         * Exclude cons/vt/ptys only, assume dialup otherwise
         * TODO: Make dialup tty determination a library call
         * for consistency (finger etc.)
         */
        if (hostname==NULL && isdialuptty(tty))
                syslog(LOG_INFO, "DIALUP %s, %s", tty, pwd->pw_name);

#ifdef LOGALL
        /*
         * Syslog each successful login, so we don't have to watch hundreds
         * of wtmp or lastlogin files.
         */
        if (hostname)
                syslog(LOG_INFO, "login from %s on %s as %s",
                       full_hostname, tty, pwd->pw_name);
        else
                syslog(LOG_INFO, "login on %s as %s",
                       tty, pwd->pw_name);
#endif

        /*
         * If fflag is on, assume caller/authenticator has logged root login.
         */
        if (rootlogin && fflag == 0)
        {
                if (hostname)
                        syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s FROM %s",
                            username, tty, full_hostname);
                else
                        syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s",
                            username, tty);
        }

        /*
         * Destroy environment unless user has requested its preservation.
         * We need to do this before setusercontext() because that may
         * set or reset some environment variables.
         */
        if (!pflag)
                environ = envinit;

        /*
         * PAM modules might add supplementary groups during pam_setcred().
         */
        if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) != 0) {
                syslog(LOG_ERR, "setusercontext() failed - exiting");
                exit(1);
        }

#ifdef USE_PAM
        if (pamh) {
                if ((e = pam_open_session(pamh, 0)) != PAM_SUCCESS) {
                        syslog(LOG_ERR, "pam_open_session: %s",
                            pam_strerror(pamh, e));
                } else if ((e = pam_setcred(pamh, PAM_ESTABLISH_CRED))
                    != PAM_SUCCESS) {
                        syslog(LOG_ERR, "pam_setcred: %s",
                            pam_strerror(pamh, e));
                }

                /*
                 * Add any environmental variables that the
                 * PAM modules may have set.
                 * Call *after* opening session!
                 */
                if (pamh) {
                  environ_pam = pam_getenvlist(pamh);
                  if (environ_pam)
                        export_pam_environment();
                }

                /*
                 * We must fork() before setuid() because we need to call
                 * pam_close_session() as root.
                 */
                pid = fork();
                if (pid < 0) {
                        err(1, "fork");
                        PAM_END;
                        exit(0);
                } else if (pid) {
                        /* parent - wait for child to finish, then cleanup
                           session */
                        setproctitle("-%s [pam]", getprogname());
                        wait(NULL);
                        PAM_END;
                        exit(0);
                } else {
                        if ((e = pam_end(pamh, PAM_SILENT)) != PAM_SUCCESS)
                                syslog(LOG_ERR, "pam_end: %s",
                                    pam_strerror(pamh, e));
                }
        }
#endif /* USE_PAM */

        /*
         * We don't need to be root anymore, so
         * set the user and session context
         */
        if (setlogin(username) != 0) {
                syslog(LOG_ERR, "setlogin(%s): %m - exiting", username);
                exit(1);
        }
        if (setusercontext(lc, pwd, pwd->pw_uid,
            LOGIN_SETALL & ~(LOGIN_SETLOGIN|LOGIN_SETGROUP)) != 0) {
                syslog(LOG_ERR, "setusercontext() failed - exiting");
                exit(1);
        }

        if (setenv("SHELL", pwd->pw_shell, 1) == -1)
                err(1, "setenv: cannot set SHELL=%s", pwd->pw_shell);
        if (setenv("HOME", pwd->pw_dir, 1) == -1)
                err(1, "setenv: cannot set HOME=%s", pwd->pw_dir);
        if (term != NULL && *term != '\0') {
                if (setenv("TERM", term, 1) == -1)              /* Preset overrides */
                        err(1, "setenv: cannot set TERM=%s", term);
        }
        else {
                if (setenv("TERM", stypeof(tty), 0) == -1)      /* Fallback doesn't */
                        err(1, "setenv: cannot set TERM=%s", stypeof(tty));
        }
        if (setenv("LOGNAME", username, 1) == -1)
                err(1, "setenv: cannot set LOGNAME=%s", username);
        if (setenv("USER", username, 1) == -1)
                err(1, "setenv: cannot set USER=%s", username);
        if (setenv("PATH", rootlogin ? _PATH_STDPATH : _PATH_DEFPATH, 0) == -1)
                err(1, "setenv: cannot set PATH=%s", rootlogin ? _PATH_STDPATH : _PATH_DEFPATH);

        if (!quietlog) {
                char    *cw;

                cw = login_getcapstr(lc, "copyright", NULL, NULL);
                if (cw != NULL && access(cw, F_OK) == 0)
                        motd(cw);
                else
                    (void)printf("%s\n\t%s %s\n",
        "Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994",
        "The Regents of the University of California. ",
        "All rights reserved.");

                (void)printf("\n");

                cw = login_getcapstr(lc, "welcome", NULL, NULL);
                if (cw == NULL || access(cw, F_OK) != 0)
                        cw = _PATH_MOTDFILE;
                motd(cw);

                cw = getenv("MAIL");    /* $MAIL may have been set by class */
                if (cw != NULL)
                        strlcpy(tbuf, cw, sizeof(tbuf));
                else
                        snprintf(tbuf, sizeof(tbuf), "%s/%s", _PATH_MAILDIR,
                            pwd->pw_name);
                if (stat(tbuf, &st) == 0 && st.st_size != 0)
                        (void)printf("You have %smail.\n",
                            (st.st_mtime > st.st_atime) ? "new " : "");
        }

        login_close(lc);

        (void)signal(SIGALRM, SIG_DFL);
        (void)signal(SIGQUIT, SIG_DFL);
        (void)signal(SIGINT, SIG_DFL);
        (void)signal(SIGTSTP, SIG_IGN);

        if (changepass) {
                if (system(_PATH_CHPASS) != 0)
                        sleepexit(1);
        }

        /*
         * Login shells have a leading '-' in front of argv[0]
         */
        if (snprintf(tbuf, sizeof(tbuf), "-%s",
            (p = strrchr(pwd->pw_shell, '/')) ? p + 1 : pwd->pw_shell) >=
            sizeof(tbuf)) {
                syslog(LOG_ERR, "user: %s: shell exceeds maximum pathname size",
                    username);
                errx(1, "shell exceeds maximum pathname size");
        }

        execlp(shell, tbuf, (char *)0);
        err(1, "%s", shell);
}

static int
auth_traditional(void)
{
        int rval;
        char *p;
        char *ep;
        char *salt;

        rval = 1;
        salt = pwd != NULL ? pwd->pw_passwd : "xx";

        p = getpass(passwd_prompt);
        ep = crypt(p, salt);

        if (pwd) {
                if (!p[0] && pwd->pw_passwd[0])
                        ep = ":";
                if (strcmp(ep, pwd->pw_passwd) == 0)
                        rval = 0;
        }

        /* clear entered password */
        memset(p, 0, strlen(p));
        return rval;
}

#ifdef USE_PAM
/*
 * Attempt to authenticate the user using PAM.  Returns 0 if the user is
 * authenticated, or 1 if not authenticated.  If some sort of PAM system
 * error occurs (e.g., the "/etc/pam.conf" file is missing) then this
 * function returns -1.  This can be used as an indication that we should
 * fall back to a different authentication mechanism.
 */
static int
auth_pam(void)
{
        const char *tmpl_user;
        const void *item;
        int rval;
        int e;
        static struct pam_conv conv;

        conv.conv = &openpam_ttyconv;

        if ((e = pam_start("login", username, &conv, &pamh)) != PAM_SUCCESS) {
                syslog(LOG_ERR, "pam_start: %s", pam_strerror(pamh, e));
                return -1;
        }
        if ((e = pam_set_item(pamh, PAM_TTY, tty)) != PAM_SUCCESS) {
                syslog(LOG_ERR, "pam_set_item(PAM_TTY): %s",
                    pam_strerror(pamh, e));
                return -1;
        }
        if (hostname != NULL &&
            (e = pam_set_item(pamh, PAM_RHOST, full_hostname)) != PAM_SUCCESS) {
                syslog(LOG_ERR, "pam_set_item(PAM_RHOST): %s",
                    pam_strerror(pamh, e));
                return -1;
        }
        e = pam_authenticate(pamh, 0);
        switch (e) {

        case PAM_SUCCESS:
                /*
                 * With PAM we support the concept of a "template"
                 * user.  The user enters a login name which is
                 * authenticated by PAM, usually via a remote service
                 * such as RADIUS or TACACS+.  If authentication
                 * succeeds, a different but related "template" name
                 * is used for setting the credentials, shell, and
                 * home directory.  The name the user enters need only
                 * exist on the remote authentication server, but the
                 * template name must be present in the local password
                 * database.
                 *
                 * This is supported by two various mechanisms in the
                 * individual modules.  However, from the application's
                 * point of view, the template user is always passed
                 * back as a changed value of the PAM_USER item.
                 */
                if ((e = pam_get_item(pamh, PAM_USER, &item)) ==
                    PAM_SUCCESS) {
                        tmpl_user = (const char *) item;
                        if (strcmp(username, tmpl_user) != 0)
                                pwd = getpwnam(tmpl_user);
                } else
                        syslog(LOG_ERR, "Couldn't get PAM_USER: %s",
                            pam_strerror(pamh, e));
                rval = 0;
                break;

        case PAM_AUTH_ERR:
        case PAM_USER_UNKNOWN:
        case PAM_MAXTRIES:
                rval = 1;
                break;

        default:
                syslog(LOG_ERR, "pam_authenticate: %s", pam_strerror(pamh, e));
                rval = -1;
                break;
        }

        if (rval == 0) {
                e = pam_acct_mgmt(pamh, 0);
                if (e == PAM_NEW_AUTHTOK_REQD) {
                        e = pam_chauthtok(pamh, PAM_CHANGE_EXPIRED_AUTHTOK);
                        if (e != PAM_SUCCESS) {
                                syslog(LOG_ERR, "pam_chauthtok: %s",
                                    pam_strerror(pamh, e));
                                rval = 1;
                        }
                } else if (e != PAM_SUCCESS) {
                        rval = 1;
                }
        }

        if (rval != 0) {
                if ((e = pam_end(pamh, e)) != PAM_SUCCESS) {
                        syslog(LOG_ERR, "pam_end: %s", pam_strerror(pamh, e));
                }
                pamh = NULL;
        }
        return rval;
}

static int
export_pam_environment(void)
{
        char    **pp;

        for (pp = environ_pam; *pp != NULL; pp++) {
                if (ok_to_export(*pp)) {
                        if (putenv(*pp) == -1)
                                err(1, "putenv: cannot set %s", *pp);
                }
                free(*pp);
        }
        return PAM_SUCCESS;
}

/*
 * Sanity checks on PAM environmental variables:
 * - Make sure there is an '=' in the string.
 * - Make sure the string doesn't run on too long.
 * - Do not export certain variables.  This list was taken from the
 *   Solaris pam_putenv(3) man page.
 */
static int
ok_to_export(const char *s)
{
        static const char *noexport[] = {
                "SHELL", "HOME", "LOGNAME", "MAIL", "CDPATH",
                "IFS", "PATH", NULL
        };
        const char **pp;
        size_t n;

        if (strlen(s) > 1024 || strchr(s, '=') == NULL)
                return 0;
        if (strncmp(s, "LD_", 3) == 0)
                return 0;
        for (pp = noexport; *pp != NULL; pp++) {
                n = strlen(*pp);
                if (s[n] == '=' && strncmp(s, *pp, n) == 0)
                        return 0;
        }
        return 1;
}
#endif /* USE_PAM */

static void
usage(void)
{

        (void)fprintf(stderr, "usage: login [-fp] [-h hostname] [username]\n");
        exit(1);
}

/*
 * Allow for authentication style and/or kerberos instance
 */

#define NBUFSIZ         UT_NAMESIZE + 64

void
getloginname(void)
{
        int ch;
        char *p;
        static char nbuf[NBUFSIZ];

        for (;;) {
                (void)printf("%s", prompt);
                for (p = nbuf; (ch = getchar()) != '\n'; ) {
                        if (ch == EOF) {
                                badlogin(username);
                                exit(0);
                        }
                        if (p < nbuf + (NBUFSIZ - 1))
                                *p++ = ch;
                }
                if (p > nbuf) {
                        if (nbuf[0] == '-')
                                (void)fprintf(stderr,
                                    "login names may not start with '-'.\n");
                        else {
                                *p = '\0';
                                username = nbuf;
                                break;
                        }
                }
        }
}

int
rootterm(char *ttyn)
{
        struct ttyent *t;

        return ((t = getttynam(ttyn)) && t->ty_status & TTY_SECURE);
}

volatile int motdinterrupt;

void
sigint(int signo __unused)
{
        motdinterrupt = 1;
}

void
motd(char *motdfile)
{
        int fd, nchars;
        sig_t oldint;
        char tbuf[256];

        if ((fd = open(motdfile, O_RDONLY, 0)) < 0)
                return;
        motdinterrupt = 0;
        oldint = signal(SIGINT, sigint);
        while ((nchars = read(fd, tbuf, sizeof(tbuf))) > 0 && !motdinterrupt)
                (void)write(fileno(stdout), tbuf, nchars);
        (void)signal(SIGINT, oldint);
        (void)close(fd);
}

/* ARGSUSED */
void
timedout(int signo)
{

        longjmp(timeout_buf, signo);
}


void
dolastlog(int quiet)
{
        struct lastlog ll;
        int fd;

        if ((fd = open(_PATH_LASTLOG, O_RDWR, 0)) >= 0) {
                (void)lseek(fd, (off_t)pwd->pw_uid * sizeof(ll), L_SET);
                if (!quiet) {
                        if (read(fd, (char *)&ll, sizeof(ll)) == sizeof(ll) &&
                            ll.ll_time != 0) {
                                (void)printf("Last login: %.*s ",
                                    24-5, (char *)ctime(&ll.ll_time));
                                if (*ll.ll_host != '\0')
                                        (void)printf("from %.*s\n",
                                            (int)sizeof(ll.ll_host),
                                            ll.ll_host);
                                else
                                        (void)printf("on %.*s\n",
                                            (int)sizeof(ll.ll_line),
                                            ll.ll_line);
                        }
                        (void)lseek(fd, (off_t)pwd->pw_uid * sizeof(ll), L_SET);
                }
                memset((void *)&ll, 0, sizeof(ll));
                (void)time(&ll.ll_time);
                (void)strncpy(ll.ll_line, tty, sizeof(ll.ll_line));
                if (hostname)
                        (void)strncpy(ll.ll_host, hostname, sizeof(ll.ll_host));
                (void)write(fd, (char *)&ll, sizeof(ll));
                (void)close(fd);
        } else {
                syslog(LOG_ERR, "cannot open %s: %m", _PATH_LASTLOG);
        }
}

void
badlogin(char *name)
{

        if (failures == 0)
                return;
        if (hostname) {
                syslog(LOG_NOTICE, "%d LOGIN FAILURE%s FROM %s",
                    failures, failures > 1 ? "S" : "", full_hostname);
                syslog(LOG_AUTHPRIV|LOG_NOTICE,
                    "%d LOGIN FAILURE%s FROM %s, %s",
                    failures, failures > 1 ? "S" : "", full_hostname, name);
        } else {
                syslog(LOG_NOTICE, "%d LOGIN FAILURE%s ON %s",
                    failures, failures > 1 ? "S" : "", tty);
                syslog(LOG_AUTHPRIV|LOG_NOTICE,
                    "%d LOGIN FAILURE%s ON %s, %s",
                    failures, failures > 1 ? "S" : "", tty, name);
        }
        failures = 0;
}

#undef  UNKNOWN
#define UNKNOWN "su"

char *
stypeof(char *ttyid)
{
        struct ttyent *t;

        if (ttyid != NULL && *ttyid != '\0') {
                t = getttynam(ttyid);
                if (t != NULL && t->ty_type != NULL)
                        return (t->ty_type);
        }
        return (UNKNOWN);
}

void
refused(char *msg, char *rtype, int lout)
{

        if (msg != NULL)
            printf("%s.\n", msg);
        if (hostname)
                syslog(LOG_NOTICE, "LOGIN %s REFUSED (%s) FROM %s ON TTY %s",
                    pwd->pw_name, rtype, full_hostname, tty);
        else
                syslog(LOG_NOTICE, "LOGIN %s REFUSED (%s) ON TTY %s",
                    pwd->pw_name, rtype, tty);
        if (lout)
                sleepexit(1);
}

void
sleepexit(int eval)
{

        (void)sleep(5);
        exit(eval);
}