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/*
pam_file - Simple PAM module to check a username in a file
Copyright (C) 2018 Ian Cowburn (ianc@noddybox.co.uk)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#define PAM_SM_AUTH
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <syslog.h>
#include <security/pam_appl.h>
#include <security/pam_modules.h>
static void RemoveNL(char *p)
{
size_t l = strlen(p);
while(l && p[l-1] == '\n')
{
p[--l] = 0;
}
}
PAM_EXTERN int pam_sm_authenticate(pam_handle_t *pam,
int flags,
int argc,
const char *argv[])
{
static const char *file_arg="file=";
static const char *mode_arg="mode=";
static const char *syslog_arg="syslog";
const char *file = NULL;
const char *mode = NULL;
int do_syslog = 0;
const char *user;
char buff[1024];
FILE *fp;
int block;
int result;
int f;
if (pam_get_user(pam, &user, NULL) != PAM_SUCCESS || user == NULL)
{
return PAM_IGNORE;
}
for(f = 0; f < argc; f++)
{
if (strncmp(file_arg, argv[f], strlen(file_arg)) == 0)
{
file = argv[f] + strlen(file_arg);
}
if (strncmp(mode_arg, argv[f], strlen(mode_arg)) == 0)
{
mode = argv[f] + strlen(mode_arg);
}
if (strcmp(syslog_arg, argv[f]) == 0)
{
do_syslog = 1;
}
}
if (!file && !mode)
{
return PAM_IGNORE;
}
block = strcmp(mode, "block") == 0;
if (!(fp = fopen(file, "r")))
{
return PAM_IGNORE;
}
if (block)
{
result = PAM_SUCCESS;
}
else
{
result = PAM_AUTH_ERR;
}
while(fgets(buff, sizeof buff, fp))
{
RemoveNL(buff);
if (strcmp(buff, user) == 0)
{
if (block)
{
result = PAM_AUTH_ERR;
}
else
{
result = PAM_SUCCESS;
}
}
}
if (do_syslog)
{
syslog(LOG_INFO, "pam_file %s user %s",
result == PAM_SUCCESS ? "allowed":"blocked",
user);
}
fclose(fp);
return result;
}
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