/*- * Copyright (c) 1980, 1987, 1988, 1991, 1993, 1994 * The Regents of the University of California. All rights reserved. * Copyright (c) 2002 Networks Associates Technologies, Inc. * All rights reserved. * * Portions of this software were developed for the FreeBSD Project by * ThinkSec AS and NAI Labs, the Security Research Division of Network * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 * ("CBOSS"), as part of the DARPA CHATS research program. * * 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. */ #if 0 #ifndef lint static char sccsid[] = "@(#)login.c 8.4 (Berkeley) 4/2/94"; #endif #endif #include __FBSDID("$FreeBSD$"); /* * login [ name ] * login -h hostname (for telnetd, etc.) * login -f name (for pre-authenticated login: datakit, xterm, etc.) */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "login.h" #include "pathnames.h" /* wrapper for KAME-special getnameinfo() */ #ifndef NI_WITHSCOPEID #define NI_WITHSCOPEID 0 #endif static int auth_pam(void); static void bail(int, int); static int export(const char *); static void export_pam_environment(void); static int motd(const char *); static void badlogin(char *); static char *getloginname(void); static void pam_syslog(const char *); static void pam_cleanup(void); static void refused(const char *, const char *, int); static const char *stypeof(char *); static void sigint(int); static void timedout(int); static void usage(void); #define TTYGRPNAME "tty" /* group to own ttys */ #define DEFAULT_BACKOFF 3 #define DEFAULT_RETRIES 10 #define DEFAULT_PROMPT "login: " #define DEFAULT_PASSWD_PROMPT "Password:" #define TERM_UNKNOWN "su" #define DEFAULT_WARN (2L * 7L * 86400L) /* Two weeks */ #define NO_SLEEP_EXIT 0 #define SLEEP_EXIT 5 /* * This bounds the time given to login. Not a define so it can * be patched on machines where it's too small. */ static u_int timeout = 300; /* Buffer for signal handling of timeout */ static jmp_buf timeout_buf; struct passwd *pwd; static int failures; static char *envinit[1]; /* empty environment list */ /* * Command line flags and arguments */ static int fflag; /* -f: do not perform authentication */ static int hflag; /* -h: login from remote host */ static char *hostname; /* hostname from command line */ static int pflag; /* -p: preserve environment */ /* * User name */ static char *username; /* user name */ static char *olduser; /* previous user name */ /* * Prompts */ static char default_prompt[] = DEFAULT_PROMPT; static const char *prompt; static char default_passwd_prompt[] = DEFAULT_PASSWD_PROMPT; static const char *passwd_prompt; static char *tty; /* * PAM data */ static pam_handle_t *pamh = NULL; static struct pam_conv pamc = { openpam_ttyconv, NULL }; static int pam_err; static int pam_silent = PAM_SILENT; static int pam_cred_established; static int pam_session_established; int main(int argc, char *argv[]) { struct group *gr; struct stat st; int retries, backoff; int ask, ch, cnt, quietlog, rootlogin, rval; uid_t uid, euid; gid_t egid; char *term; char *p, *ttyn; char tname[sizeof(_PATH_TTY) + 10]; char *arg0; const char *shell = NULL; login_cap_t *lc = NULL; pid_t pid; (void)signal(SIGQUIT, SIG_IGN); (void)signal(SIGINT, SIG_IGN); (void)signal(SIGHUP, SIG_IGN); if (setjmp(timeout_buf)) { if (failures) badlogin(username); (void)fprintf(stderr, "Login timed out after %d seconds\n", timeout); bail(NO_SLEEP_EXIT, 0); } (void)signal(SIGALRM, timedout); (void)alarm(timeout); (void)setpriority(PRIO_PROCESS, 0, 0); openlog("login", LOG_ODELAY, LOG_AUTH); 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 != 0) errx(1, "-h option: %s", strerror(EPERM)); if (strlen(optarg) >= MAXHOSTNAMELEN) errx(1, "-h option: %s: exceeds maximum " "hostname size", optarg); hflag = 1; hostname = optarg; break; case 'p': pflag = 1; break; case '?': default: if (uid == 0) syslog(LOG_ERR, "invalid flag %c", ch); usage(); } argc -= optind; argv += optind; if (argc > 0) { username = strdup(*argv); if (username == NULL) err(1, "strdup()"); ask = 0; } else { ask = 1; } for (cnt = getdtablesize(); cnt > 2; cnt--) (void)close(cnt); /* * Get current TTY */ 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, "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; /* * Try to authenticate the user until we succeed or time out. */ for (cnt = 0;; ask = 1) { if (ask) { fflag = 0; if (olduser != NULL) free(olduser); olduser = username; username = getloginname(); } rootlogin = 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(olduser, username) != 0) { if (failures > (pwd ? 0 : 1)) badlogin(olduser); } /* * Load the PAM policy and set some variables */ pam_err = pam_start("login", username, &pamc, &pamh); if (pam_err != PAM_SUCCESS) { pam_syslog("pam_start()"); bail(NO_SLEEP_EXIT, 1); } pam_err = pam_set_item(pamh, PAM_TTY, tty); if (pam_err != PAM_SUCCESS) { pam_syslog("pam_set_item(PAM_TTY)"); bail(NO_SLEEP_EXIT, 1); } pam_err = pam_set_item(pamh, PAM_RHOST, hostname); if (pam_err != PAM_SUCCESS) { pam_syslog("pam_set_item(PAM_RHOST)"); bail(NO_SLEEP_EXIT, 1); } pwd = getpwnam(username); if (pwd != NULL && pwd->pw_uid == 0) rootlogin = 1; /* * If the -f option was specified and the caller is * root or the caller isn't changing their uid, don't * authenticate. */ if (pwd != NULL && fflag && (uid == (uid_t)0 || uid == (uid_t)pwd->pw_uid)) { /* already authenticated */ rval = 0; } else { fflag = 0; (void)setpriority(PRIO_PROCESS, 0, -4); rval = auth_pam(); (void)setpriority(PRIO_PROCESS, 0, 0); } if (pwd && rval == 0) break; pam_cleanup(); (void)printf("Login incorrect\n"); failures++; /* * Allow up to 'retry' (10) attempts, but start * backing off after 'backoff' (3) attempts. */ if (++cnt > backoff) { if (cnt >= retries) { badlogin(username); bail(SLEEP_EXIT, 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); quietlog = login_getcapbool(lc, "hushlogin", 0); /* * Switching needed for NFS with root access disabled. * * XXX: This change fails to modify the additional groups for the * process, and as such, may restrict rights normally granted * through those groups. */ (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 = strdup("/"); if (pwd->pw_dir == NULL) { syslog(LOG_NOTICE, "strdup(): %m"); bail(SLEEP_EXIT, 1); } } (void)seteuid(euid); (void)setegid(egid); if (!quietlog) quietlog = access(_PATH_HUSHLOGIN, F_OK) == 0; shell = login_getcapstr(lc, "shell", pwd->pw_shell, pwd->pw_shell); if (*pwd->pw_shell == '\0') pwd->pw_shell = strdup(_PATH_BSHELL); if (pwd->pw_shell == NULL) { syslog(LOG_NOTICE, "strdup(): %m"); bail(SLEEP_EXIT, 1); } if (*shell == '\0') /* Not overridden */ shell = pwd->pw_shell; if ((shell = strdup(shell)) == NULL) { syslog(LOG_NOTICE, "strdup(): %m"); bail(SLEEP_EXIT, 1); } /* * 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); /* * Exclude cons/vt/ptys only, assume dialup otherwise * TODO: Make dialup tty determination a library call * for consistency (finger etc.) */ if (hflag && 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 (hflag) syslog(LOG_INFO, "login from %s on %s as %s", 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 (hflag) syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s FROM %s", username, tty, hostname); else syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s", username, tty); } /* * Destroy environment unless user has requested its * preservation - but preserve TERM in all cases */ term = getenv("TERM"); if (!pflag) environ = envinit; if (term != NULL) setenv("TERM", term, 0); /* * 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"); bail(NO_SLEEP_EXIT, 1); } pam_err = pam_setcred(pamh, pam_silent|PAM_ESTABLISH_CRED); if (pam_err != PAM_SUCCESS) { pam_syslog("pam_setcred()"); bail(NO_SLEEP_EXIT, 1); } pam_cred_established = 1; pam_err = pam_open_session(pamh, pam_silent); if (pam_err != PAM_SUCCESS) { pam_syslog("pam_open_session()"); bail(NO_SLEEP_EXIT, 1); } pam_session_established = 1; /* * We must fork() before setuid() because we need to call * pam_close_session() as root. */ pid = fork(); if (pid < 0) { err(1, "fork"); } else if (pid != 0) { /* * Parent: wait for child to finish, then clean up * session. */ wait(NULL); bail(NO_SLEEP_EXIT, 0); } /* * NOTICE: We are now in the child process! */ /* * Add any environment variables the PAM modules may have set. */ export_pam_environment(); /* * We're done with PAM now; our parent will deal with the rest. */ pam_end(pamh, 0); pamh = NULL; /* * We don't need to be root anymore, so set the login name and * the UID. */ if (setlogin(username) != 0) { syslog(LOG_ERR, "setlogin(%s): %m - exiting", username); bail(NO_SLEEP_EXIT, 1); } if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETALL & ~(LOGIN_SETLOGIN|LOGIN_SETGROUP)) != 0) { syslog(LOG_ERR, "setusercontext() failed - exiting"); exit(1); } (void)setenv("SHELL", pwd->pw_shell, 1); (void)setenv("HOME", pwd->pw_dir, 1); (void)setenv("TERM", stypeof(tty), 0); (void)setenv("LOGNAME", username, 1); (void)setenv("USER", username, 1); (void)setenv("PATH", rootlogin ? _PATH_STDPATH : _PATH_DEFPATH, 0); if (!quietlog) { const char *cw; cw = login_getcapstr(lc, "copyright", NULL, NULL); if (cw == NULL || motd(cw) == -1) (void)printf("%s", copyright); (void)printf("\n"); cw = login_getcapstr(lc, "welcome", NULL, NULL); if (cw != NULL && access(cw, F_OK) == 0) motd(cw); else motd(_PATH_MOTDFILE); if (login_getcapbool(lc, "nocheckmail", 0) == 0) { /* $MAIL may have been set by class. */ cw = getenv("MAIL"); if (cw == NULL) { asprintf((char **)&cw, "%s/%s", _PATH_MAILDIR, pwd->pw_name); } if (cw && stat(cw, &st) == 0 && st.st_size != 0) (void)printf("You have %smail.\n", (st.st_mtime > st.st_atime) ? "new " : ""); if (getenv("MAIL") == NULL) free((char *)cw); } } login_close(lc); (void)signal(SIGALRM, SIG_DFL); (void)signal(SIGQUIT, SIG_DFL); (void)signal(SIGINT, SIG_DFL); (void)signal(SIGTSTP, SIG_IGN); /* * Login shells have a leading '-' in front of argv[0] */ p = strrchr(pwd->pw_shell, '/'); if (asprintf(&arg0, "-%s", p ? p + 1 : pwd->pw_shell) >= MAXPATHLEN) { syslog(LOG_ERR, "user: %s: shell exceeds maximum pathname size", username); errx(1, "shell exceeds maximum pathname size"); } else if (arg0 == NULL) { err(1, "asprintf()"); } execlp(shell, arg0, (char *)0); err(1, "%s", shell); /* * That's it, folks! */ } /* * 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; pam_err = pam_authenticate(pamh, pam_silent); switch (pam_err) { 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. */ pam_err = pam_get_item(pamh, PAM_USER, &item); if (pam_err == PAM_SUCCESS) { tmpl_user = (const char *)item; if (strcmp(username, tmpl_user) != 0) pwd = getpwnam(tmpl_user); } else { pam_syslog("pam_get_item(PAM_USER)"); } rval = 0; break; case PAM_AUTH_ERR: case PAM_USER_UNKNOWN: case PAM_MAXTRIES: rval = 1; break; default: pam_syslog("pam_authenticate()"); rval = -1; break; } if (rval == 0) { pam_err = pam_acct_mgmt(pamh, pam_silent); switch (pam_err) { case PAM_SUCCESS: break; case PAM_NEW_AUTHTOK_REQD: pam_err = pam_chauthtok(pamh, pam_silent|PAM_CHANGE_EXPIRED_AUTHTOK); if (pam_err != PAM_SUCCESS) { pam_syslog("pam_chauthtok()"); rval = 1; } break; default: pam_syslog("pam_acct_mgmt()"); rval = 1; break; } } if (rval != 0) { pam_end(pamh, pam_err); pamh = NULL; } return (rval); } /* * Export any environment variables PAM modules may have set */ static void export_pam_environment() { char **pam_env; char **pp; pam_env = pam_getenvlist(pamh); if (pam_env != NULL) { for (pp = pam_env; *pp != NULL; pp++) { (void)export(*pp); free(*pp); } } } /* * Perform sanity checks on an environment variable: * - 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. * Then export it. */ static int 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); } (void)putenv(s); return (1); } static void usage() { (void)fprintf(stderr, "usage: login [-fp] [-h hostname] [username]\n"); exit(1); } /* * Prompt user and read login name from stdin. */ static char * getloginname() { char *nbuf, *p; int ch; nbuf = malloc(MAXLOGNAME); if (nbuf == NULL) err(1, "malloc()"); do { (void)printf("%s", prompt); for (p = nbuf; (ch = getchar()) != '\n'; ) { if (ch == EOF) { badlogin(username); bail(NO_SLEEP_EXIT, 0); } if (p < nbuf + MAXLOGNAME - 1) *p++ = ch; } } while (p == nbuf); *p = '\0'; if (nbuf[0] == '-') { pam_silent = 0; memmove(nbuf, nbuf + 1, strlen(nbuf)); } else { pam_silent = PAM_SILENT; } return nbuf; } /* * SIGINT handler for motd(). */ static volatile int motdinterrupt; static void sigint(int signo __unused) { motdinterrupt = 1; } /* * Display the contents of a file (such as /etc/motd). */ static int motd(const char *motdfile) { sig_t oldint; FILE *f; int ch; if ((f = fopen(motdfile, "r")) == NULL) return (-1); motdinterrupt = 0; oldint = signal(SIGINT, sigint); while ((ch = fgetc(f)) != EOF && !motdinterrupt) putchar(ch); signal(SIGINT, oldint); if (ch != EOF || ferror(f)) { fclose(f); return (-1); } fclose(f); return (0); } /* * SIGALRM handler, to enforce login prompt timeout. * * XXX This can potentially confuse the hell out of PAM. We should * XXX instead implement a conversation function that returns * XXX PAM_CONV_ERR when interrupted by a signal, and have the signal * XXX handler just set a flag. */ static void timedout(int signo __unused) { longjmp(timeout_buf, signo); } void badlogin(char *name) { if (failures == 0) return; if (hflag) { syslog(LOG_NOTICE, "%d LOGIN FAILURE%s FROM %s", failures, failures > 1 ? "S" : "", hostname); syslog(LOG_AUTHPRIV|LOG_NOTICE, "%d LOGIN FAILURE%s FROM %s, %s", failures, failures > 1 ? "S" : "", 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; } const 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 (TERM_UNKNOWN); } void refused(const char *msg, const char *rtype, int lout) { if (msg != NULL) printf("%s.\n", msg); if (hflag) syslog(LOG_NOTICE, "LOGIN %s REFUSED (%s) FROM %s ON TTY %s", pwd->pw_name, rtype, hostname, tty); else syslog(LOG_NOTICE, "LOGIN %s REFUSED (%s) ON TTY %s", pwd->pw_name, rtype, tty); if (lout) bail(SLEEP_EXIT, 1); } /* * Log a PAM error */ void pam_syslog(const char *msg) { syslog(LOG_ERR, "%s: %s", msg, pam_strerror(pamh, pam_err)); } /* * Shut down PAM */ void pam_cleanup() { if (pamh != NULL) { if (pam_session_established) { pam_err = pam_close_session(pamh, 0); if (pam_err != PAM_SUCCESS) pam_syslog("pam_close_session()"); } pam_session_established = 0; if (pam_cred_established) { pam_err = pam_setcred(pamh, pam_silent|PAM_DELETE_CRED); if (pam_err != PAM_SUCCESS) pam_syslog("pam_setcred()"); } pam_cred_established = 0; pam_end(pamh, pam_err); pamh = NULL; } } /* * Exit, optionally after sleeping a few seconds */ void bail(int sec, int eval) { pam_cleanup(); (void)sleep(sec); exit(eval); }