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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.
*/
#define _BSD_SOURCE
#include <pwd.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.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
#include <security/pam_modules.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();
}
/* --- authentication management functions (only) --- */
PAM_EXTERN
int pam_sm_authenticate(pam_handle_t *pamh,int flags,int argc
,const char **argv)
{
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 || (strlen(userName) <= 0)) {
/* Don't let them use a NULL username... */
pam_get_user(pamh,&userName,NULL);
if (retval != PAM_SUCCESS)
return PAM_SERVICE_ERR;
}
pw = getpwnam(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;
}
/* There should be no more errors from here on */
retval=PAM_AUTH_ERR;
/* This loop assumes that PAM_SUCCESS == 0
and PAM_AUTH_ERR != 0 */
while((fgets(shellFileLine,255,shellFile) != NULL)
&& retval) {
if (shellFileLine[strlen(shellFileLine) - 1] == '\n')
shellFileLine[strlen(shellFileLine) - 1] = '\0';
retval = strcmp(shellFileLine, userShell);
}
fclose(shellFile);
if(retval)
retval = PAM_AUTH_ERR;
return retval;
}
PAM_EXTERN
int pam_sm_setcred(pam_handle_t *pamh,int flags,int argc
,const char **argv)
{
return PAM_SUCCESS;
}
#ifdef PAM_STATIC
/* static module data */
struct pam_module _pam_shells_modstruct = {
"pam_shells",
pam_sm_authenticate,
pam_sm_setcred,
NULL,
NULL,
NULL,
NULL,
};
#endif
/* end of module definition */
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