/* $NetBSD: login_pam.c,v 1.26 2020/02/08 13:44:35 kamil 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 #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_pam.c,v 1.26 2020/02/08 13:44:35 kamil Exp $"); #endif /* not lint */ /* * 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 #include #include #include "pathnames.h" #include "common.h" #if 0 static int rootterm(char *); #endif static void usage(void) __attribute__((__noreturn__)); static struct pam_conv pamc = { openpam_ttyconv, NULL }; #define TTYGRPNAME "tty" /* name of group to own ttys */ #define DEFAULT_BACKOFF 3 #define DEFAULT_RETRIES 10 static struct passwd pwres; static char pwbuf[1024]; static struct group grs, *grp; static char grbuf[1024]; extern char **environ; int main(int argc, char *argv[]) { struct stat st; int ask, ch, cnt, fflag, pflag, quietlog, rootlogin; int auth_passed; uid_t uid, saved_uid; gid_t saved_gid, saved_gids[NGROUPS_MAX]; int nsaved_gids; char *domain, *p, *ttyn; char tbuf[MAXPATHLEN + 2], tname[sizeof(_PATH_TTY) + 10]; char localhost[MAXHOSTNAMELEN + 1]; int login_retries = DEFAULT_RETRIES, login_backoff = DEFAULT_BACKOFF; char *shell = NULL; login_cap_t *lc = NULL; pam_handle_t *pamh = NULL; int pam_err; sig_t oint, oabrt, oquit, oalrm; const void *newuser; int pam_silent = PAM_SILENT; pid_t xpid, pid; int status; char *saved_term; char **pamenv; tbuf[0] = '\0'; nested = NULL; oabrt = signal(SIGABRT, SIG_IGN); oalrm = signal(SIGALRM, timedout); oint = signal(SIGINT, SIG_IGN); oquit = signal(SIGQUIT, SIG_IGN); (void)alarm(timeout); (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 my supply -a to pass the actual * server address. */ domain = NULL; if (gethostname(localhost, sizeof(localhost)) < 0) syslog(LOG_ERR, "couldn't get local hostname: %m"); else domain = strchr(localhost, '.'); localhost[sizeof(localhost) - 1] = '\0'; fflag = pflag = 0; have_ss = 0; uid = getuid(); while ((ch = getopt(argc, argv, "a:fh:p")) != -1) switch (ch) { case 'a': if (uid) { errno = EPERM; err(EXIT_FAILURE, "-a option"); } decode_ss(optarg); break; case 'f': fflag = 1; break; case 'h': if (uid) { errno = EPERM; err(EXIT_FAILURE, "-h option"); } if (domain && (p = strchr(optarg, '.')) != NULL && strcasecmp(p, domain) == 0) *p = '\0'; hostname = optarg; break; case 'p': pflag = 1; break; default: case '?': usage(); break; } setproctitle(NULL); argc -= optind; argv += optind; if (*argv) { username = trimloginname(*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); } } /* 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; } for (cnt = 0;; ask = 1) { if (ask) { fflag = 0; username = trimloginname(getloginname()); } rootlogin = 0; auth_passed = 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); failures = 0; } #define PAM_END(msg) do { \ syslog(LOG_ERR, "%s: %s", msg, pam_strerror(pamh, pam_err)); \ warnx("%s: %s", msg, pam_strerror(pamh, pam_err)); \ pam_end(pamh, pam_err); \ sleepexit(EXIT_FAILURE); \ } while (/*CONSTCOND*/0) pam_err = pam_start("login", username, &pamc, &pamh); if (pam_err != PAM_SUCCESS) { if (pamh != NULL) PAM_END("pam_start"); /* Things went really bad... */ syslog(LOG_ERR, "pam_start failed: %s", pam_strerror(pamh, pam_err)); errx(EXIT_FAILURE, "pam_start failed"); } #define PAM_SET_ITEM(item, var) do { \ pam_err = pam_set_item(pamh, (item), (var)); \ if (pam_err != PAM_SUCCESS) \ PAM_END("pam_set_item(" # item ")"); \ } while (/*CONSTCOND*/0) /* * Fill hostname tty, and nested user */ PAM_SET_ITEM(PAM_RHOST, hostname); PAM_SET_ITEM(PAM_TTY, tty); if (nested) PAM_SET_ITEM(PAM_NUSER, nested); if (have_ss) PAM_SET_ITEM(PAM_SOCKADDR, &ss); /* * Don't check for errors, because we don't want to give * out any information. */ pwd = NULL; (void)getpwnam_r(username, &pwres, pwbuf, sizeof(pwbuf), &pwd); /* * 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); /* * 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 */ auth_passed = 1; goto skip_auth; } } (void)setpriority(PRIO_PROCESS, 0, -4); switch(pam_err = pam_authenticate(pamh, pam_silent)) { case PAM_SUCCESS: /* * PAM can change the user, refresh * username, pwd, and lc. */ pam_err = pam_get_item(pamh, PAM_USER, &newuser); if (pam_err != PAM_SUCCESS) PAM_END("pam_get_item(PAM_USER)"); username = newuser; /* * Don't check for errors, because we don't want to give * out any information. */ pwd = NULL; (void)getpwnam_r(username, &pwres, pwbuf, sizeof(pwbuf), &pwd); lc = login_getpwclass(pwd); auth_passed = 1; switch (pam_err = pam_acct_mgmt(pamh, pam_silent)) { 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_END("pam_chauthtok"); break; case PAM_AUTH_ERR: case PAM_USER_UNKNOWN: case PAM_MAXTRIES: auth_passed = 0; break; default: PAM_END("pam_acct_mgmt"); break; } break; case PAM_AUTH_ERR: case PAM_USER_UNKNOWN: case PAM_MAXTRIES: auth_passed = 0; break; default: PAM_END("pam_authenticate"); break; } (void)setpriority(PRIO_PROCESS, 0, 0); skip_auth: /* * If the user exists and authentication passed, * get out of the loop and login the user. */ if (pwd && auth_passed) 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); pam_end(pamh, PAM_SUCCESS); sleepexit(EXIT_FAILURE); } sleep((u_int)((cnt - login_backoff) * 5)); } } /* committed to login -- turn off timeout */ (void)alarm((u_int)0); endpwent(); quietlog = login_getcapbool(lc, "hushlogin", 0); /* * 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); if (initgroups(username, pwd->pw_gid) == -1) { syslog(LOG_ERR, "initgroups failed"); pam_end(pamh, PAM_SUCCESS); exit(EXIT_FAILURE); } (void)seteuid(pwd->pw_uid); if (chdir(pwd->pw_dir) != 0) { if (login_getcapbool(lc, "requirehome", 0)) { (void)printf("Home directory %s required\n", pwd->pw_dir); pam_end(pamh, PAM_SUCCESS); exit(EXIT_FAILURE); } (void)printf("No home directory %s!\n", pwd->pw_dir); if (chdir("/") == -1) { pam_end(pamh, PAM_SUCCESS); exit(EXIT_FAILURE); } pwd->pw_dir = __UNCONST("/"); (void)printf("Logging in with home = \"/\".\n"); } if (!quietlog) { quietlog = access(_PATH_HUSHLOGIN, F_OK) == 0; pam_silent = quietlog ? PAM_SILENT : 0; } /* regain special privileges */ (void)setegid(saved_gid); (void)seteuid(saved_uid); if (setgroups(nsaved_gids, saved_gids) == -1) { syslog(LOG_ERR, "setgroups failed: %m"); pam_end(pamh, PAM_SUCCESS); exit(EXIT_FAILURE); } (void)getgrnam_r(TTYGRPNAME, &grs, grbuf, sizeof(grbuf), &grp); (void)chown(ttyn, pwd->pw_uid, (grp != NULL) ? grp->gr_gid : pwd->pw_gid); if (ttyaction(ttyn, "login", pwd->pw_name)) (void)printf("Warning: ttyaction failed.\n"); /* Nothing else left to fail -- really log in. */ update_db(quietlog, rootlogin, fflag); if (nested == NULL && setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETLOGIN) != 0) { syslog(LOG_ERR, "setusercontext failed"); pam_end(pamh, PAM_SUCCESS); exit(EXIT_FAILURE); } /* * Establish groups */ if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) != 0) { syslog(LOG_ERR, "setusercontext failed"); pam_end(pamh, PAM_SUCCESS); exit(EXIT_FAILURE); } pam_err = pam_setcred(pamh, pam_silent|PAM_ESTABLISH_CRED); if (pam_err != PAM_SUCCESS) PAM_END("pam_setcred"); pam_err = pam_open_session(pamh, pam_silent); if (pam_err != PAM_SUCCESS) PAM_END("pam_open_session"); /* * Fork because we need to call pam_closesession as root. * Make sure signals cannot kill the parent. * This has been handled in the begining of main. */ switch(pid = fork()) { case -1: pam_err = pam_close_session(pamh, 0); if (pam_err != PAM_SUCCESS) { syslog(LOG_ERR, "pam_close_session: %s", pam_strerror(pamh, pam_err)); warnx("pam_close_session: %s", pam_strerror(pamh, pam_err)); } syslog(LOG_ERR, "fork failed: %m"); warn("fork failed"); pam_end(pamh, pam_err); exit(EXIT_FAILURE); break; case 0: /* Child */ break; default: /* * Parent: wait for the child to terminate * and call pam_close_session. */ if ((xpid = waitpid(pid, &status, 0)) != pid) { pam_err = pam_close_session(pamh, 0); if (pam_err != PAM_SUCCESS) { syslog(LOG_ERR, "pam_close_session: %s", pam_strerror(pamh, pam_err)); warnx("pam_close_session: %s", pam_strerror(pamh, pam_err)); } pam_end(pamh, pam_err); if (xpid != -1) warnx("wrong PID: %d != %d", pid, xpid); else warn("wait for pid %d failed", pid); exit(EXIT_FAILURE); } (void)signal(SIGABRT, oabrt); (void)signal(SIGALRM, oalrm); (void)signal(SIGINT, oint); (void)signal(SIGQUIT, oquit); if ((pam_err = pam_close_session(pamh, 0)) != PAM_SUCCESS) { syslog(LOG_ERR, "pam_close_session: %s", pam_strerror(pamh, pam_err)); warnx("pam_close_session: %s", pam_strerror(pamh, pam_err)); } pam_end(pamh, PAM_SUCCESS); exit(EXIT_SUCCESS); break; } /* * The child: starting here, we don't have to care about * handling PAM issues if we exit, the parent will do the * job when we exit. * * Destroy environment unless user has requested its preservation. * Try to preserve TERM anyway. */ saved_term = getenv("TERM"); if (!pflag) { environ = envinit; if (saved_term) setenv("TERM", saved_term, 0); } if (*pwd->pw_shell == '\0') pwd->pw_shell = __UNCONST(_PATH_BSHELL); shell = login_getcapstr(lc, "shell", pwd->pw_shell, pwd->pw_shell); if (*shell == '\0') shell = pwd->pw_shell; if ((pwd->pw_shell = strdup(shell)) == NULL) { syslog(LOG_ERR, "Cannot alloc mem"); exit(EXIT_FAILURE); } (void)setenv("HOME", pwd->pw_dir, 1); (void)setenv("SHELL", pwd->pw_shell, 1); if (term[0] == '\0') { const char *tt = stypeof(tty); if (tt == NULL) tt = login_getcapstr(lc, "term", NULL, NULL); /* 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); /* * Add PAM environement */ if ((pamenv = pam_getenvlist(pamh)) != NULL) { char **envitem; for (envitem = pamenv; *envitem; envitem++) { if (putenv(*envitem) == -1) free(*envitem); } free(pamenv); } /* This drops root privs */ if (setusercontext(lc, pwd, pwd->pw_uid, (LOGIN_SETALL & ~LOGIN_SETLOGIN)) != 0) { syslog(LOG_ERR, "setusercontext failed"); exit(EXIT_FAILURE); } if (!quietlog) { const char *fname; fname = login_getcapstr(lc, "copyright", NULL, NULL); if (fname != NULL && access(fname, F_OK) == 0) motd(fname); else (void)printf("%s", copyrightstr); fname = login_getcapstr(lc, "welcome", NULL, NULL); if (fname == NULL || access(fname, F_OK) != 0) 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 " : ""); } login_close(lc); tbuf[0] = '-'; (void)strlcpy(tbuf + 1, (p = strrchr(pwd->pw_shell, '/')) ? p + 1 : pwd->pw_shell, sizeof(tbuf) - 1); (void)signal(SIGABRT, oabrt); (void)signal(SIGALRM, oalrm); (void)signal(SIGINT, oint); (void)signal(SIGQUIT, oquit); (void)signal(SIGTSTP, SIG_IGN); execlp(pwd->pw_shell, tbuf, NULL); err(EXIT_FAILURE, "%s", pwd->pw_shell); } static void usage(void) { (void)fprintf(stderr, "Usage: %s [-fp] [-a address] [-h hostname] [username]\n", getprogname()); exit(EXIT_FAILURE); } #if 0 static int rootterm(char *ttyn) { struct ttyent *t; return ((t = getttynam(ttyn)) && t->ty_status & TTY_SECURE); } #endif