1 /*- 2 * Copyright (c) 2002 Networks Associates Technology, Inc. 3 * All rights reserved. 4 * 5 * This software was developed for the FreeBSD Project by ThinkSec AS and 6 * Network Associates Laboratories, the Security Research Division of 7 * Network Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 8 * ("CBOSS"), as part of the DARPA CHATS research program. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. The name of the author may not be used to endorse or promote 19 * products derived from this software without specific prior written 20 * permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * $P4: //depot/projects/openpam/bin/su/su.c#8 $ 35 */ 36 37 #include <sys/param.h> 38 #include <sys/wait.h> 39 40 #include <err.h> 41 #include <pwd.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <string.h> 45 #include <syslog.h> 46 #include <unistd.h> 47 48 #include <security/pam_appl.h> 49 #include <security/openpam.h> /* for openpam_ttyconv() */ 50 51 extern char **environ; 52 53 static pam_handle_t *pamh; 54 static struct pam_conv pamc; 55 56 static void 57 usage(void) 58 { 59 60 fprintf(stderr, "Usage: su [login [args]]\n"); 61 exit(1); 62 } 63 64 int 65 main(int argc, char *argv[]) 66 { 67 char hostname[MAXHOSTNAMELEN]; 68 const char *user, *tty; 69 char **args, **pam_envlist, **pam_env; 70 struct passwd *pwd; 71 int o, pam_err, status; 72 pid_t pid; 73 74 while ((o = getopt(argc, argv, "h")) != -1) 75 switch (o) { 76 case 'h': 77 default: 78 usage(); 79 } 80 81 argc -= optind; 82 argv += optind; 83 84 /* initialize PAM */ 85 pamc.conv = &openpam_ttyconv; 86 pam_start("su", argc ? *argv : "root", &pamc, &pamh); 87 88 /* set some items */ 89 gethostname(hostname, sizeof(hostname)); 90 if ((pam_err = pam_set_item(pamh, PAM_RHOST, hostname)) != PAM_SUCCESS) 91 goto pamerr; 92 user = getlogin(); 93 if ((pam_err = pam_set_item(pamh, PAM_RUSER, user)) != PAM_SUCCESS) 94 goto pamerr; 95 tty = ttyname(STDERR_FILENO); 96 if ((pam_err = pam_set_item(pamh, PAM_TTY, tty)) != PAM_SUCCESS) 97 goto pamerr; 98 99 /* authenticate the applicant */ 100 if ((pam_err = pam_authenticate(pamh, 0)) != PAM_SUCCESS) 101 goto pamerr; 102 if ((pam_err = pam_acct_mgmt(pamh, 0)) == PAM_NEW_AUTHTOK_REQD) 103 pam_err = pam_chauthtok(pamh, PAM_CHANGE_EXPIRED_AUTHTOK); 104 if (pam_err != PAM_SUCCESS) 105 goto pamerr; 106 107 /* establish the requested credentials */ 108 if ((pam_err = pam_setcred(pamh, PAM_ESTABLISH_CRED)) != PAM_SUCCESS) 109 goto pamerr; 110 111 /* authentication succeeded; open a session */ 112 if ((pam_err = pam_open_session(pamh, 0)) != PAM_SUCCESS) 113 goto pamerr; 114 115 /* get mapped user name; PAM may have changed it */ 116 pam_err = pam_get_item(pamh, PAM_USER, (const void **)&user); 117 if (pam_err != PAM_SUCCESS || (pwd = getpwnam(user)) == NULL) 118 goto pamerr; 119 120 /* set uid and groups */ 121 if (initgroups(pwd->pw_name, pwd->pw_gid) == -1) { 122 warn("initgroups()"); 123 goto err; 124 } 125 if (setgid(pwd->pw_gid) == -1) { 126 warn("setgid()"); 127 goto err; 128 } 129 if (setuid(pwd->pw_uid) == -1) { 130 warn("setuid()"); 131 goto err; 132 } 133 134 /* export PAM environment */ 135 if ((pam_envlist = pam_getenvlist(pamh)) != NULL) { 136 for (pam_env = pam_envlist; *pam_env != NULL; ++pam_env) { 137 putenv(*pam_env); 138 free(*pam_env); 139 } 140 free(pam_envlist); 141 } 142 143 /* build argument list */ 144 if ((args = calloc(argc + 2, sizeof *args)) == NULL) { 145 warn("calloc()"); 146 goto err; 147 } 148 *args = pwd->pw_shell; 149 memcpy(args + 1, argv, argc * sizeof *args); 150 151 /* fork and exec */ 152 switch ((pid = fork())) { 153 case -1: 154 warn("fork()"); 155 goto err; 156 case 0: 157 /* child: start a shell */ 158 execve(*args, args, environ); 159 warn("execve()"); 160 _exit(1); 161 default: 162 /* parent: wait for child to exit */ 163 waitpid(pid, &status, 0); 164 165 /* close the session and release PAM resources */ 166 pam_err = pam_close_session(pamh, 0); 167 pam_end(pamh, pam_err); 168 169 exit(WEXITSTATUS(status)); 170 } 171 172 pamerr: 173 pam_end(pamh, pam_err); 174 fprintf(stderr, "Sorry\n"); 175 exit(1); 176 err: 177 pam_end(pamh, pam_err); 178 exit(1); 179 } 180