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NetBSD/usr.bin/login/login.c

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/* $NetBSD: login.c,v 1.105 2014/11/12 22:23:38 aymeric Exp $ */
/*-
* 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. 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.
*/
#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1980, 1987, 1988, 1991, 1993, 1994\
The Regents of the University of California. All rights reserved.");
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)login.c 8.4 (Berkeley) 4/2/94";
#endif
__RCSID("$NetBSD: login.c,v 1.105 2014/11/12 22:23:38 aymeric Exp $");
#endif /* not lint */
/*
* login [ name ]
* login -h hostname (for telnetd, etc.)
* login -f name (for pre-authenticated login: datakit, xterm, etc.)
*/
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/file.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <err.h>
#include <errno.h>
#include <grp.h>
#include <pwd.h>
#include <setjmp.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <time.h>
#include <ttyent.h>
#include <tzfile.h>
#include <unistd.h>
#include <sysexits.h>
#ifdef SUPPORT_UTMP
#include <utmp.h>
#endif
#ifdef SUPPORT_UTMPX
#include <utmpx.h>
#endif
#include <util.h>
#ifdef SKEY
#include <skey.h>
#endif
#ifdef KERBEROS5
#include <krb5/krb5.h>
#include <krb5/com_err.h>
#endif
#ifdef LOGIN_CAP
#include <login_cap.h>
#endif
#include <vis.h>
#include "pathnames.h"
#include "common.h"
#ifdef KERBEROS5
int login_krb5_forwardable_tgt = 0;
static int login_krb5_get_tickets = 1;
static int login_krb5_retain_ccache = 0;
#endif
static void checknologin(char *);
#ifdef KERBEROS5
int k5login(struct passwd *, char *, char *, char *);
void k5destroy(void);
int k5_read_creds(const char *);
int k5_write_creds(void);
#endif
#if defined(KERBEROS5)
static void dofork(void);
#endif
static void usage(void) __attribute__((__noreturn__));
#define TTYGRPNAME "tty" /* name of group to own ttys */
#define DEFAULT_BACKOFF 3
#define DEFAULT_RETRIES 10
#if defined(KERBEROS5)
int has_ccache = 0;
int notickets = 1;
extern krb5_context kcontext;
extern int have_forward;
static char *instance;
extern char *krb5tkfile_env;
extern int krb5_configured;
#endif
#if defined(KERBEROS5)
#define KERBEROS_CONFIGURED krb5_configured
#endif
extern char **environ;
int
main(int argc, char *argv[])
{
struct group *gr;
struct stat st;
int ask, ch, cnt, fflag, hflag, pflag, sflag, quietlog, rootlogin, rval;
uid_t uid, saved_uid;
gid_t saved_gid, saved_gids[NGROUPS_MAX];
int nsaved_gids;
#ifdef notdef
char *domain;
#endif
char *p, *ttyn;
const char *pwprompt;
char tbuf[MAXPATHLEN + 2], tname[sizeof(_PATH_TTY) + 10];
char localhost[MAXHOSTNAMELEN + 1];
int need_chpass, require_chpass;
int login_retries = DEFAULT_RETRIES,
login_backoff = DEFAULT_BACKOFF;
time_t pw_warntime = _PASSWORD_WARNDAYS * SECSPERDAY;
char *loginname = NULL;
#ifdef KERBEROS5
int Fflag;
krb5_error_code kerror;
#endif
#if defined(KERBEROS5)
int got_tickets = 0;
#endif
#ifdef LOGIN_CAP
char *shell = NULL;
login_cap_t *lc = NULL;
#endif
tbuf[0] = '\0';
rval = 0;
pwprompt = NULL;
nested = NULL;
need_chpass = require_chpass = 0;
(void)signal(SIGALRM, timedout);
(void)alarm(timeout);
(void)signal(SIGQUIT, SIG_IGN);
(void)signal(SIGINT, SIG_IGN);
(void)setpriority(PRIO_PROCESS, 0, 0);
openlog("login", 0, 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/utmpx and wtmp/wtmpx
* -a in addition to -h, a server may supply -a to pass the actual
* server address.
* -s is used to force use of S/Key or equivalent.
*/
if (gethostname(localhost, sizeof(localhost)) < 0) {
syslog(LOG_ERR, "couldn't get local hostname: %m");
strcpy(hostname, "amnesiac");
}
#ifdef notdef
domain = strchr(localhost, '.');
#endif
localhost[sizeof(localhost) - 1] = '\0';
fflag = hflag = pflag = sflag = 0;
have_ss = 0;
#ifdef KERBEROS5
Fflag = 0;
have_forward = 0;
#endif
uid = getuid();
while ((ch = getopt(argc, argv, "a:Ffh:ps")) != -1)
switch (ch) {
case 'a':
if (uid)
errx(EXIT_FAILURE, "-a option: %s", strerror(EPERM));
decode_ss(optarg);
#ifdef notdef
(void)sockaddr_snprintf(optarg,
sizeof(struct sockaddr_storage), "%a", (void *)&ss);
#endif
break;
case 'F':
#ifdef KERBEROS5
Fflag = 1;
#endif
/* FALLTHROUGH */
case 'f':
fflag = 1;
break;
case 'h':
if (uid)
errx(EXIT_FAILURE, "-h option: %s", strerror(EPERM));
hflag = 1;
#ifdef notdef
if (domain && (p = strchr(optarg, '.')) != NULL &&
strcasecmp(p, domain) == 0)
*p = '\0';
#endif
hostname = optarg;
break;
case 'p':
pflag = 1;
break;
case 's':
sflag = 1;
break;
default:
case '?':
usage();
break;
}
setproctitle(NULL);
argc -= optind;
argv += optind;
if (*argv) {
username = loginname = *argv;
ask = 0;
} else
ask = 1;
#ifdef F_CLOSEM
(void)fcntl(3, F_CLOSEM, 0);
#else
for (cnt = getdtablesize(); cnt > 2; cnt--)
(void)close(cnt);
#endif
ttyn = ttyname(STDIN_FILENO);
if (ttyn == NULL || *ttyn == '\0') {
(void)snprintf(tname, sizeof(tname), "%s??", _PATH_TTY);
ttyn = tname;
}
if ((tty = strstr(ttyn, "/pts/")) != NULL)
++tty;
else if ((tty = strrchr(ttyn, '/')) != NULL)
++tty;
else
tty = ttyn;
if (issetugid()) {
nested = strdup(user_from_uid(getuid(), 0));
if (nested == NULL) {
syslog(LOG_ERR, "strdup: %m");
sleepexit(EXIT_FAILURE);
}
}
#ifdef LOGIN_CAP
/* Get "login-retries" and "login-backoff" from default class */
if ((lc = login_getclass(NULL)) != NULL) {
login_retries = (int)login_getcapnum(lc, "login-retries",
DEFAULT_RETRIES, DEFAULT_RETRIES);
login_backoff = (int)login_getcapnum(lc, "login-backoff",
DEFAULT_BACKOFF, DEFAULT_BACKOFF);
login_close(lc);
lc = NULL;
}
#endif
#ifdef KERBEROS5
kerror = krb5_init_context(&kcontext);
if (kerror) {
/*
* If Kerberos is not configured, that is, we are
* not using Kerberos, do not log the error message.
* However, if Kerberos is configured, and the
* context init fails for some other reason, we need
* to issue a no tickets warning to the user when the
* login succeeds.
*/
if (kerror != ENXIO) { /* XXX NetBSD-local Heimdal hack */
syslog(LOG_NOTICE,
"%s when initializing Kerberos context",
error_message(kerror));
krb5_configured = 1;
}
login_krb5_get_tickets = 0;
}
#endif /* KERBEROS5 */
for (cnt = 0;; ask = 1) {
#if defined(KERBEROS5)
if (login_krb5_get_tickets)
k5destroy();
#endif
if (ask) {
fflag = 0;
loginname = getloginname();
}
rootlogin = 0;
#ifdef KERBEROS5
if ((instance = strchr(loginname, '/')) != NULL)
*instance++ = '\0';
else
instance = __UNCONST("");
#endif
username = trimloginname(loginname);
/*
* 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);
failures = 0;
}
(void)strlcpy(tbuf, username, sizeof(tbuf));
pwd = getpwnam(username);
#ifdef LOGIN_CAP
/*
* Establish the class now, before we might goto
* within the next block. pwd can be NULL since it
* falls back to the "default" class if it is.
*/
lc = login_getclass(pwd ? pwd->pw_class : NULL);
#endif
/*
* 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) {
if (pwd->pw_uid == 0)
rootlogin = 1;
if (fflag && (uid == 0 || uid == pwd->pw_uid)) {
/* already authenticated */
#ifdef KERBEROS5
if (login_krb5_get_tickets && Fflag)
k5_read_creds(username);
#endif
break;
} else if (pwd->pw_passwd[0] == '\0') {
/* pretend password okay */
rval = 0;
goto ttycheck;
}
}
fflag = 0;
(void)setpriority(PRIO_PROCESS, 0, -4);
#ifdef SKEY
if (skey_haskey(username) == 0) {
static char skprompt[80];
const char *skinfo = skey_keyinfo(username);
(void)snprintf(skprompt, sizeof(skprompt),
"Password [ %s ]:",
skinfo ? skinfo : "error getting challenge");
pwprompt = skprompt;
} else
#endif
pwprompt = "Password:";
p = getpass(pwprompt);
if (pwd == NULL) {
rval = 1;
goto skip;
}
#ifdef KERBEROS5
if (login_krb5_get_tickets &&
k5login(pwd, instance, localhost, p) == 0) {
rval = 0;
got_tickets = 1;
}
#endif
#if defined(KERBEROS5)
if (got_tickets)
goto skip;
#endif
#ifdef SKEY
if (skey_haskey(username) == 0 &&
skey_passcheck(username, p) != -1) {
rval = 0;
goto skip;
}
#endif
if (!sflag && *pwd->pw_passwd != '\0' &&
!strcmp(crypt(p, pwd->pw_passwd), pwd->pw_passwd)) {
rval = 0;
require_chpass = 1;
goto skip;
}
rval = 1;
skip:
memset(p, 0, strlen(p));
(void)setpriority(PRIO_PROCESS, 0, 0);
ttycheck:
/*
* If trying to log in as root without Kerberos,
* but with insecure terminal, refuse the login attempt.
*/
if (pwd && !rval && rootlogin && !rootterm(tty)) {
(void)printf("Login incorrect or refused on this "
"terminal.\n");
if (hostname)
syslog(LOG_NOTICE,
"LOGIN %s REFUSED FROM %s ON TTY %s",
pwd->pw_name, hostname, tty);
else
syslog(LOG_NOTICE,
"LOGIN %s REFUSED ON TTY %s",
pwd->pw_name, tty);
continue;
}
if (pwd && !rval)
break;
(void)printf("Login incorrect or refused on this "
"terminal.\n");
failures++;
cnt++;
/*
* We allow login_retries tries, but after login_backoff
* we start backing off. These default to 10 and 3
* respectively.
*/
if (cnt > login_backoff) {
if (cnt >= login_retries) {
badlogin(username);
sleepexit(EXIT_FAILURE);
}
sleep((u_int)((cnt - login_backoff) * 5));
}
}
/* committed to login -- turn off timeout */
(void)alarm((u_int)0);
endpwent();
/* if user not super-user, check for disabled logins */
#ifdef LOGIN_CAP
if (!login_getcapbool(lc, "ignorenologin", rootlogin))
checknologin(login_getcapstr(lc, "nologin", NULL, NULL));
#else
if (!rootlogin)
checknologin(NULL);
#endif
#ifdef LOGIN_CAP
quietlog = login_getcapbool(lc, "hushlogin", 0);
#else
quietlog = 0;
#endif
/* Temporarily give up special privileges so we can change */
/* into NFS-mounted homes that are exported for non-root */
/* access and have mode 7x0 */
saved_uid = geteuid();
saved_gid = getegid();
nsaved_gids = getgroups(NGROUPS_MAX, saved_gids);
(void)setegid(pwd->pw_gid);
initgroups(username, pwd->pw_gid);
(void)seteuid(pwd->pw_uid);
if (chdir(pwd->pw_dir) < 0) {
#ifdef LOGIN_CAP
if (login_getcapbool(lc, "requirehome", 0)) {
(void)printf("Home directory %s required\n",
pwd->pw_dir);
sleepexit(EXIT_FAILURE);
}
#endif
(void)printf("No home directory %s!\n", pwd->pw_dir);
if (chdir("/") == -1)
exit(EXIT_FAILURE);
pwd->pw_dir = __UNCONST("/");
(void)printf("Logging in with home = \"/\".\n");
}
if (!quietlog)
quietlog = access(_PATH_HUSHLOGIN, F_OK) == 0;
/* regain special privileges */
(void)seteuid(saved_uid);
setgroups(nsaved_gids, saved_gids);
(void)setegid(saved_gid);
#ifdef LOGIN_CAP
pw_warntime = login_getcaptime(lc, "password-warn",
_PASSWORD_WARNDAYS * SECSPERDAY,
_PASSWORD_WARNDAYS * SECSPERDAY);
#endif
(void)gettimeofday(&now, NULL);
if (pwd->pw_expire) {
if (now.tv_sec >= pwd->pw_expire) {
(void)printf("Sorry -- your account has expired.\n");
sleepexit(EXIT_FAILURE);
} else if (pwd->pw_expire - now.tv_sec < pw_warntime &&
!quietlog)
(void)printf("Warning: your account expires on %s",
ctime(&pwd->pw_expire));
}
if (pwd->pw_change) {
if (pwd->pw_change == _PASSWORD_CHGNOW)
need_chpass = 1;
else if (now.tv_sec >= pwd->pw_change) {
(void)printf("Sorry -- your password has expired.\n");
sleepexit(EXIT_FAILURE);
} else if (pwd->pw_change - now.tv_sec < pw_warntime &&
!quietlog)
(void)printf("Warning: your password expires on %s",
ctime(&pwd->pw_change));
}
/* Nothing else left to fail -- really log in. */
update_db(quietlog, rootlogin, fflag);
(void)chown(ttyn, pwd->pw_uid,
(gr = getgrnam(TTYGRPNAME)) ? gr->gr_gid : pwd->pw_gid);
if (ttyaction(ttyn, "login", pwd->pw_name))
(void)printf("Warning: ttyaction failed.\n");
#if defined(KERBEROS5)
/* Fork so that we can call kdestroy */
if (! login_krb5_retain_ccache && has_ccache)
dofork();
#endif
/* Destroy environment unless user has requested its preservation. */
if (!pflag)
environ = envinit;
#ifdef LOGIN_CAP
if (nested == NULL && setusercontext(lc, pwd, pwd->pw_uid,
LOGIN_SETLOGIN) != 0) {
syslog(LOG_ERR, "setusercontext failed");
exit(EXIT_FAILURE);
}
if (setusercontext(lc, pwd, pwd->pw_uid,
(LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETLOGIN))) != 0) {
syslog(LOG_ERR, "setusercontext failed");
exit(EXIT_FAILURE);
}
#else
(void)setgid(pwd->pw_gid);
initgroups(username, pwd->pw_gid);
if (nested == NULL && setlogin(pwd->pw_name) < 0)
syslog(LOG_ERR, "setlogin() failure: %m");
/* Discard permissions last so can't get killed and drop core. */
if (rootlogin)
(void)setuid(0);
else
(void)setuid(pwd->pw_uid);
#endif
if (*pwd->pw_shell == '\0')
pwd->pw_shell = __UNCONST(_PATH_BSHELL);
#ifdef LOGIN_CAP
if ((shell = login_getcapstr(lc, "shell", NULL, NULL)) != NULL) {
if ((shell = strdup(shell)) == NULL) {
syslog(LOG_ERR, "Cannot alloc mem");
sleepexit(EXIT_FAILURE);
}
pwd->pw_shell = shell;
}
#endif
(void)setenv("HOME", pwd->pw_dir, 1);
(void)setenv("SHELL", pwd->pw_shell, 1);
if (term[0] == '\0') {
const char *tt = stypeof(tty);
#ifdef LOGIN_CAP
if (tt == NULL)
tt = login_getcapstr(lc, "term", NULL, NULL);
#endif
/* unknown term -> "su" */
(void)strlcpy(term, tt != NULL ? tt : "su", sizeof(term));
}
(void)setenv("TERM", term, 0);
(void)setenv("LOGNAME", pwd->pw_name, 1);
(void)setenv("USER", pwd->pw_name, 1);
#ifdef LOGIN_CAP
setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETPATH);
#else
(void)setenv("PATH", _PATH_DEFPATH, 0);
#endif
#ifdef KERBEROS5
if (krb5tkfile_env)
(void)setenv("KRB5CCNAME", krb5tkfile_env, 1);
#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, hostname);
else
syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s",
username, tty);
}
#if defined(KERBEROS5)
if (KERBEROS_CONFIGURED && !quietlog && notickets == 1)
(void)printf("Warning: no Kerberos tickets issued.\n");
#endif
if (!quietlog) {
const char *fname;
#ifdef LOGIN_CAP
fname = login_getcapstr(lc, "copyright", NULL, NULL);
if (fname != NULL && access(fname, F_OK) == 0)
motd(fname);
else
#endif
(void)printf("%s", copyrightstr);
#ifdef LOGIN_CAP
fname = login_getcapstr(lc, "welcome", NULL, NULL);
if (fname == NULL || access(fname, F_OK) != 0)
#endif
fname = _PATH_MOTDFILE;
motd(fname);
(void)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 " : "");
}
#ifdef LOGIN_CAP
login_close(lc);
#endif
(void)signal(SIGALRM, SIG_DFL);
(void)signal(SIGQUIT, SIG_DFL);
(void)signal(SIGINT, SIG_DFL);
(void)signal(SIGTSTP, SIG_IGN);
tbuf[0] = '-';
(void)strlcpy(tbuf + 1, (p = strrchr(pwd->pw_shell, '/')) ?
p + 1 : pwd->pw_shell, sizeof(tbuf) - 1);
/* Wait to change password until we're unprivileged */
if (need_chpass) {
if (!require_chpass)
(void)printf(
"Warning: your password has expired. Please change it as soon as possible.\n");
else {
int status;
(void)printf(
"Your password has expired. Please choose a new one.\n");
switch (fork()) {
case -1:
warn("fork");
sleepexit(EXIT_FAILURE);
case 0:
execl(_PATH_BINPASSWD, "passwd", NULL);
_exit(EXIT_FAILURE);
default:
if (wait(&status) == -1 ||
WEXITSTATUS(status))
sleepexit(EXIT_FAILURE);
}
}
}
#ifdef KERBEROS5
if (login_krb5_get_tickets)
k5_write_creds();
#endif
execlp(pwd->pw_shell, tbuf, NULL);
err(EXIT_FAILURE, "%s", pwd->pw_shell);
}
#if defined(KERBEROS5)
/*
* This routine handles cleanup stuff, and the like.
* It exists only in the child process.
*/
static void
dofork(void)
{
pid_t child, wchild;
switch (child = fork()) {
case 0:
return; /* Child process */
case -1:
err(EXIT_FAILURE, "Can't fork");
/*NOTREACHED*/
default:
break;
}
/*
* Setup stuff? This would be things we could do in parallel
* with login
*/
if (chdir("/") == -1) /* Let's not keep the fs busy... */
err(EXIT_FAILURE, "Can't chdir to `/'");
/* If we're the parent, watch the child until it dies */
while ((wchild = wait(NULL)) != child)
if (wchild == -1)
err(EXIT_FAILURE, "Can't wait");
/* Cleanup stuff */
/* Run kdestroy to destroy tickets */
if (login_krb5_get_tickets)
k5destroy();
/* Leave */
exit(EXIT_SUCCESS);
}
#endif
static void
checknologin(char *fname)
{
int fd, nchars;
char tbuf[8192];
if ((fd = open(fname ? fname : _PATH_NOLOGIN, O_RDONLY, 0)) >= 0) {
while ((nchars = read(fd, tbuf, sizeof(tbuf))) > 0)
(void)write(fileno(stdout), tbuf, nchars);
sleepexit(EXIT_SUCCESS);
}
}
static void
usage(void)
{
(void)fprintf(stderr,
"Usage: %s [-Ffps] [-a address] [-h hostname] [username]\n",
getprogname());
exit(EXIT_FAILURE);
}
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