diff options
Diffstat (limited to 'modules/pam_unix/unix_update.c')
| -rw-r--r-- | modules/pam_unix/unix_update.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/modules/pam_unix/unix_update.c b/modules/pam_unix/unix_update.c new file mode 100644 index 0000000..6ea7ea5 --- /dev/null +++ b/modules/pam_unix/unix_update.c @@ -0,0 +1,191 @@ +/* + * This program is designed to run with sufficient privilege + * to read and write all of the unix password databases. + * Its purpose is to allow updating the databases when + * SELinux confinement of the caller domain prevents them to + * do that themselves. + * + * The password is read from the standard input. The exit status of + * this program indicates whether the password was updated or not. + * + * Copyright information is located at the end of the file. + * + */ + +#include "config.h" + +#include <stdarg.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <syslog.h> +#include <unistd.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <pwd.h> +#include <shadow.h> +#include <signal.h> +#include <time.h> +#include <sys/time.h> + +#include <security/_pam_types.h> +#include <security/_pam_macros.h> + +#include "passverify.h" + +static int +set_password(const char *forwho, const char *shadow, const char *remember) +{ + struct passwd *pwd = NULL; + int retval; + char pass[MAXPASS + 1]; + char towhat[MAXPASS + 1]; + int npass = 0; + /* we don't care about number format errors because the helper + should be called internally only */ + int doshadow = atoi(shadow); + int nremember = atoi(remember); + char *passwords[] = { pass, towhat }; + + /* read the password from stdin (a pipe from the pam_unix module) */ + + npass = read_passwords(STDIN_FILENO, 2, passwords); + + if (npass != 2) { /* is it a valid password? */ + if (npass == 1) { + helper_log_err(LOG_DEBUG, "no new password supplied"); + memset(pass, '\0', MAXPASS); + } else { + helper_log_err(LOG_DEBUG, "no valid passwords supplied"); + } + return PAM_AUTHTOK_ERR; + } + + if (lock_pwdf() != PAM_SUCCESS) + return PAM_AUTHTOK_LOCK_BUSY; + + pwd = getpwnam(forwho); + + if (pwd == NULL) { + retval = PAM_USER_UNKNOWN; + goto done; + } + + /* If real caller uid is not root we must verify that + received old pass agrees with the current one. + We always allow change from null pass. */ + if (getuid()) { + retval = helper_verify_password(forwho, pass, 1); + if (retval != PAM_SUCCESS) { + goto done; + } + } + + /* first, save old password */ + if (save_old_password(forwho, pass, nremember)) { + retval = PAM_AUTHTOK_ERR; + goto done; + } + + if (doshadow || is_pwd_shadowed(pwd)) { + retval = unix_update_shadow(forwho, towhat); + if (retval == PAM_SUCCESS) + if (!is_pwd_shadowed(pwd)) + retval = unix_update_passwd(forwho, "x"); + } else { + retval = unix_update_passwd(forwho, towhat); + } + +done: + memset(pass, '\0', MAXPASS); + memset(towhat, '\0', MAXPASS); + + unlock_pwdf(); + + if (retval == PAM_SUCCESS) { + return PAM_SUCCESS; + } else { + return PAM_AUTHTOK_ERR; + } +} + +int main(int argc, char *argv[]) +{ + char *option; + + /* + * Catch or ignore as many signal as possible. + */ + setup_signals(); + + /* + * we establish that this program is running with non-tty stdin. + * this is to discourage casual use. It does *NOT* prevent an + * intruder from repeatadly running this program to determine the + * password of the current user (brute force attack, but one for + * which the attacker must already have gained access to the user's + * account). + */ + + if (isatty(STDIN_FILENO) || argc != 5 ) { + helper_log_err(LOG_NOTICE + ,"inappropriate use of Unix helper binary [UID=%d]" + ,getuid()); + fprintf(stderr + ,"This binary is not designed for running in this way\n" + "-- the system administrator has been informed\n"); + sleep(10); /* this should discourage/annoy the user */ + return PAM_SYSTEM_ERR; + } + + /* We must be root to read/update shadow. + */ + if (geteuid() != 0) { + return PAM_CRED_INSUFFICIENT; + } + + option = argv[2]; + + if (strcmp(option, "update") == 0) { + /* Attempting to change the password */ + return set_password(argv[1], argv[3], argv[4]); + } + + return PAM_SYSTEM_ERR; +} + +/* + * Copyright (c) Andrew G. Morgan, 1996. All rights reserved + * Copyright (c) Red Hat, Inc., 2007, 2008. 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, and the entire permission notice in its entirety, + * including the disclaimer of warranties. + * 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. The name of the author may not be used to endorse or promote + * products derived from this software without specific prior + * written permission. + * + * ALTERNATIVELY, this product may be distributed under the terms of + * the GNU Public License, in which case the provisions of the GPL are + * required INSTEAD OF the above restrictions. (This clause is + * necessary due to a potential bad interaction between the GPL and + * the restrictions contained in a BSD-style copyright.) + * + * THIS SOFTWARE IS PROVIDED ``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 AUTHOR 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. + */ |