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/* PAM Make Home Dir module
This module will create a users home directory if it does not exist
when the session begins. This allows users to be present in central
database (such as nis, kerb or ldap) without using a distributed
file system or pre-creating a large number of directories.
Here is a sample /etc/pam.d/login file for Debian GNU/Linux
2.1:
auth requisite pam_securetty.so
auth sufficient pam_ldap.so
auth required pam_unix.so
auth optional pam_group.so
auth optional pam_mail.so
account requisite pam_time.so
account sufficient pam_ldap.so
account required pam_unix.so
session required pam_mkhomedir.so skel=/etc/skel/ umask=0022
session required pam_unix.so
session optional pam_lastlog.so
password required pam_unix.so
Released under the GNU LGPL version 2 or later
Copyright (c) Red Hat, Inc. 2009
Originally written by Jason Gunthorpe <jgg@debian.org> Feb 1999
Structure taken from pam_lastlogin by Andrew Morgan
<morgan@parc.power.net> 1996
*/
#include "config.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>
#include <unistd.h>
#include <pwd.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <syslog.h>
#include <signal.h>
/*
* here, we make a definition for the externally accessible function
* in this file (this definition is required for static a module
* but strongly encouraged generally) it is used to instruct the
* modules include file to define the function prototypes.
*/
#define PAM_SM_SESSION
#include <security/pam_modules.h>
#include <security/_pam_macros.h>
#include <security/pam_modutil.h>
#include <security/pam_ext.h>
#include "pam_cc_compat.h"
#include "pam_inline.h"
/* argument parsing */
#define MKHOMEDIR_DEBUG 020 /* be verbose about things */
#define MKHOMEDIR_QUIET 040 /* keep quiet about things */
struct options_t {
int ctrl;
const char *umask;
const char *skeldir;
};
typedef struct options_t options_t;
static void
_pam_parse (const pam_handle_t *pamh, int flags, int argc, const char **argv,
options_t *opt)
{
opt->ctrl = 0;
opt->umask = "0022";
opt->skeldir = "/etc/skel";
/* does the application require quiet? */
if ((flags & PAM_SILENT) == PAM_SILENT)
opt->ctrl |= MKHOMEDIR_QUIET;
/* step through arguments */
for (; argc-- > 0; ++argv)
{
const char *str;
if (!strcmp(*argv, "silent")) {
opt->ctrl |= MKHOMEDIR_QUIET;
} else if (!strcmp(*argv, "debug")) {
opt->ctrl |= MKHOMEDIR_DEBUG;
} else if ((str = pam_str_skip_prefix(*argv, "umask=")) != NULL) {
opt->umask = str;
} else if ((str = pam_str_skip_prefix(*argv, "skel=")) != NULL) {
opt->skeldir = str;
} else {
pam_syslog(pamh, LOG_ERR, "unknown option: %s", *argv);
}
}
}
/* Do the actual work of creating a home dir */
static int
create_homedir (pam_handle_t *pamh, options_t *opt,
const char *user, const char *dir)
{
int retval, child;
struct sigaction newsa, oldsa;
/* Mention what is happening, if the notification fails that is OK */
if (!(opt->ctrl & MKHOMEDIR_QUIET))
pam_info(pamh, _("Creating directory '%s'."), dir);
D(("called."));
/*
* This code arranges that the demise of the child does not cause
* the application to receive a signal it is not expecting - which
* may kill the application or worse.
*/
memset(&newsa, '\0', sizeof(newsa));
newsa.sa_handler = SIG_DFL;
sigaction(SIGCHLD, &newsa, &oldsa);
if (opt->ctrl & MKHOMEDIR_DEBUG) {
pam_syslog(pamh, LOG_DEBUG, "Executing mkhomedir_helper.");
}
/* fork */
child = fork();
if (child == 0) {
static char *envp[] = { NULL };
const char *args[] = { NULL, NULL, NULL, NULL, NULL };
if (pam_modutil_sanitize_helper_fds(pamh, PAM_MODUTIL_PIPE_FD,
PAM_MODUTIL_PIPE_FD,
PAM_MODUTIL_PIPE_FD) < 0)
_exit(PAM_SYSTEM_ERR);
/* exec the mkhomedir helper */
args[0] = MKHOMEDIR_HELPER;
args[1] = user;
args[2] = opt->umask;
args[3] = opt->skeldir;
DIAG_PUSH_IGNORE_CAST_QUAL;
execve(MKHOMEDIR_HELPER, (char **)args, envp);
DIAG_POP_IGNORE_CAST_QUAL;
/* should not get here: exit with error */
D(("helper binary is not available"));
_exit(PAM_SYSTEM_ERR);
} else if (child > 0) {
int rc;
while ((rc=waitpid(child, &retval, 0)) < 0 && errno == EINTR);
if (rc < 0) {
pam_syslog(pamh, LOG_ERR, "waitpid failed: %m");
retval = PAM_SYSTEM_ERR;
} else if (!WIFEXITED(retval)) {
pam_syslog(pamh, LOG_ERR, "mkhomedir_helper abnormal exit: %d", retval);
retval = PAM_SYSTEM_ERR;
} else {
retval = WEXITSTATUS(retval);
}
} else {
D(("fork failed"));
pam_syslog(pamh, LOG_ERR, "fork failed: %m");
retval = PAM_SYSTEM_ERR;
}
sigaction(SIGCHLD, &oldsa, NULL); /* restore old signal handler */
if (opt->ctrl & MKHOMEDIR_DEBUG) {
pam_syslog(pamh, LOG_DEBUG, "mkhomedir_helper returned %d", retval);
}
if (retval != PAM_SUCCESS && !(opt->ctrl & MKHOMEDIR_QUIET)) {
pam_error(pamh, _("Unable to create and initialize directory '%s'."),
dir);
}
D(("returning %d", retval));
return retval;
}
/* --- authentication management functions (only) --- */
int
pam_sm_open_session (pam_handle_t *pamh, int flags, int argc,
const char **argv)
{
int retval;
options_t opt;
const void *user;
const struct passwd *pwd;
struct stat St;
/* Parse the flag values */
_pam_parse(pamh, flags, argc, argv, &opt);
/* Determine the user name so we can get the home directory */
retval = pam_get_item(pamh, PAM_USER, &user);
if (retval != PAM_SUCCESS || user == NULL || *(const char *)user == '\0')
{
pam_syslog(pamh, LOG_NOTICE, "Cannot obtain the user name.");
return PAM_USER_UNKNOWN;
}
/* Get the password entry */
pwd = pam_modutil_getpwnam (pamh, user);
if (pwd == NULL)
{
pam_syslog(pamh, LOG_NOTICE, "User unknown.");
D(("couldn't identify user %s", user));
return PAM_CRED_INSUFFICIENT;
}
/* Stat the home directory, if something exists then we assume it is
correct and return a success*/
if (stat(pwd->pw_dir, &St) == 0) {
if (opt.ctrl & MKHOMEDIR_DEBUG) {
pam_syslog(pamh, LOG_DEBUG, "Home directory %s already exists.",
pwd->pw_dir);
}
return PAM_SUCCESS;
}
return create_homedir(pamh, &opt, user, pwd->pw_dir);
}
/* Ignore */
int pam_sm_close_session (pam_handle_t * pamh UNUSED, int flags UNUSED,
int argc UNUSED, const char **argv UNUSED)
{
return PAM_SUCCESS;
}
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