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/* pam_shells module */
#define SHELL_FILE "/etc/shells"
/*
* by Erik Troan <ewt@redhat.com>, Red Hat Software.
* August 5, 1996.
* This code shamelessly ripped from the pam_securetty module.
*/
#include "config.h"
#include <pwd.h>
#include <stdarg.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <syslog.h>
#include <unistd.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_AUTH
#define PAM_SM_ACCOUNT
#include <security/pam_modules.h>
#include <security/_pam_modutil.h>
/* some syslogging */
static void _pam_log(int err, const char *format, ...)
{
va_list args;
va_start(args, format);
openlog("PAM-shells", LOG_CONS|LOG_PID, LOG_AUTH);
vsyslog(err, format, args);
va_end(args);
closelog();
}
static int perform_check(pam_handle_t *pamh, int flags)
{
int retval = PAM_AUTH_ERR;
const char *userName;
char *userShell;
char shellFileLine[256];
struct stat sb;
struct passwd * pw;
FILE * shellFile;
retval = pam_get_user(pamh, &userName, NULL);
if (retval != PAM_SUCCESS) {
return PAM_SERVICE_ERR;
}
if (!userName || (userName[0] == '\0')) {
/* Don't let them use a NULL username... */
retval = pam_get_user(pamh,&userName,NULL);
if (retval != PAM_SUCCESS)
return PAM_SERVICE_ERR;
/* It could still be NULL the second time. */
if (!userName || (userName[0] == '\0'))
return PAM_SERVICE_ERR;
}
pw = _pammodutil_getpwnam(pamh, userName);
if (!pw) {
return PAM_AUTH_ERR; /* user doesn't exist */
}
userShell = pw->pw_shell;
if (stat(SHELL_FILE,&sb)) {
_pam_log(LOG_ERR, "%s cannot be stat'd (it probably does not exist)",
SHELL_FILE);
return PAM_AUTH_ERR; /* must have /etc/shells */
}
if ((sb.st_mode & S_IWOTH) || !S_ISREG(sb.st_mode)) {
_pam_log(LOG_ERR, "%s is either world writable or not a normal file",
SHELL_FILE);
return PAM_AUTH_ERR;
}
shellFile = fopen(SHELL_FILE,"r");
if (shellFile == NULL) { /* Check that we opened it successfully */
_pam_log(LOG_ERR,
"Error opening %s", SHELL_FILE);
return PAM_SERVICE_ERR;
}
retval = 1;
while(retval && (fgets(shellFileLine, 255, shellFile) != NULL)) {
if (shellFileLine[strlen(shellFileLine) - 1] == '\n')
shellFileLine[strlen(shellFileLine) - 1] = '\0';
retval = strcmp(shellFileLine, userShell);
}
fclose(shellFile);
if (retval) {
return PAM_AUTH_ERR;
} else {
return PAM_SUCCESS;
}
}
/* --- authentication management functions (only) --- */
PAM_EXTERN
int pam_sm_authenticate(pam_handle_t *pamh, int flags, int argc,
const char **argv)
{
return perform_check(pamh, flags);
}
PAM_EXTERN
int pam_sm_setcred(pam_handle_t *pamh, int flags, int argc,const char **argv)
{
return PAM_SUCCESS;
}
/* --- account management functions (only) --- */
PAM_EXTERN
int pam_sm_acct_mgmt(pam_handle_t *pamh, int flags, int argc,
const char **argv)
{
return perform_check(pamh, flags);
}
#ifdef PAM_STATIC
/* static module data */
struct pam_module _pam_shells_modstruct = {
"pam_shells",
pam_sm_authenticate,
pam_sm_setcred,
pam_sm_acct_mgmt,
NULL,
NULL,
NULL,
};
#endif /* PAM_STATIC */
/* end of module definition */
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