1 /*- 2 * Copyright (c) 2002-2003 Networks Associates Technology, Inc. 3 * Copyright (c) 2004-2011 Dag-Erling Smørgrav 4 * All rights reserved. 5 * 6 * This software was developed for the FreeBSD Project by ThinkSec AS and 7 * Network Associates Laboratories, the Security Research Division of 8 * Network Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 9 * ("CBOSS"), as part of the DARPA CHATS research program. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. The name of the author may not be used to endorse or promote 20 * products derived from this software without specific prior written 21 * permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 * 35 * $OpenPAM: openpam_borrow_cred.c 938 2017-04-30 21:34:42Z des $ 36 */ 37 38 #ifdef HAVE_CONFIG_H 39 # include "config.h" 40 #endif 41 42 #include <sys/param.h> 43 44 #include <grp.h> 45 #include <limits.h> 46 #include <pwd.h> 47 #include <stdlib.h> 48 #include <unistd.h> 49 50 #include <security/pam_appl.h> 51 52 #include "openpam_impl.h" 53 #include "openpam_cred.h" 54 55 /* 56 * OpenPAM extension 57 * 58 * Temporarily borrow user credentials 59 */ 60 61 int 62 openpam_borrow_cred(pam_handle_t *pamh, 63 const struct passwd *pwd) 64 { 65 struct pam_saved_cred *scred; 66 const void *scredp; 67 int r; 68 69 ENTERI(pwd->pw_uid); 70 r = pam_get_data(pamh, PAM_SAVED_CRED, &scredp); 71 if (r == PAM_SUCCESS && scredp != NULL) { 72 openpam_log(PAM_LOG_LIBDEBUG, 73 "already operating under borrowed credentials"); 74 RETURNC(PAM_SYSTEM_ERR); 75 } 76 if (geteuid() != 0 && geteuid() != pwd->pw_uid) { 77 openpam_log(PAM_LOG_LIBDEBUG, "called with non-zero euid: %d", 78 (int)geteuid()); 79 RETURNC(PAM_PERM_DENIED); 80 } 81 scred = calloc(1, sizeof *scred); 82 if (scred == NULL) 83 RETURNC(PAM_BUF_ERR); 84 scred->euid = geteuid(); 85 scred->egid = getegid(); 86 r = getgroups(NGROUPS_MAX, scred->groups); 87 if (r < 0) { 88 FREE(scred); 89 RETURNC(PAM_SYSTEM_ERR); 90 } 91 scred->ngroups = r; 92 r = pam_set_data(pamh, PAM_SAVED_CRED, scred, &openpam_free_data); 93 if (r != PAM_SUCCESS) { 94 FREE(scred); 95 RETURNC(r); 96 } 97 if (geteuid() == pwd->pw_uid) 98 RETURNC(PAM_SUCCESS); 99 if (initgroups(pwd->pw_name, pwd->pw_gid) < 0 || 100 setegid(pwd->pw_gid) < 0 || seteuid(pwd->pw_uid) < 0) { 101 openpam_restore_cred(pamh); 102 RETURNC(PAM_SYSTEM_ERR); 103 } 104 RETURNC(PAM_SUCCESS); 105 } 106 107 /* 108 * Error codes: 109 * 110 * =pam_set_data 111 * PAM_SYSTEM_ERR 112 * PAM_BUF_ERR 113 * PAM_PERM_DENIED 114 */ 115 116 /** 117 * The =openpam_borrow_cred function saves the current credentials and 118 * switches to those of the user specified by its =pwd argument. 119 * The affected credentials are the effective UID, the effective GID, and 120 * the group access list. 121 * The original credentials can be restored using =openpam_restore_cred. 122 * 123 * >setegid 2 124 * >seteuid 2 125 * >setgroups 2 126 */ 127