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/*
* Author: Damien Miller
* Copyright (c) 1999 Damien Miller <djm@mindrot.org>
* All rights reserved
* Created: Thursday December 30 1999
* PAM authentication and session management code.
*/
#include "includes.h"
#ifdef USE_PAM
#include "ssh.h"
#include "xmalloc.h"
#include "servconf.h"
RCSID("$Id: auth-pam.c,v 1.5 2000/05/31 01:20:12 damien Exp $");
#define NEW_AUTHTOK_MSG \
"Warning: You password has expired, please change it now"
/* Callbacks */
static int pamconv(int num_msg, const struct pam_message **msg,
struct pam_response **resp, void *appdata_ptr);
void pam_cleanup_proc(void *context);
void pam_msg_cat(const char *msg);
/* module-local variables */
static struct pam_conv conv = {
pamconv,
NULL
};
static struct pam_handle_t *pamh = NULL;
static const char *pampasswd = NULL;
static char *pam_msg = NULL;
/* PAM conversation function. This is really a kludge to get the password */
/* into PAM and to pick up any messages generated by PAM into pamconv_msg */
static int pamconv(int num_msg, const struct pam_message **msg,
struct pam_response **resp, void *appdata_ptr)
{
struct pam_response *reply;
int count;
/* PAM will free this later */
reply = malloc(num_msg * sizeof(*reply));
if (reply == NULL)
return PAM_CONV_ERR;
for(count = 0; count < num_msg; count++) {
switch (msg[count]->msg_style) {
case PAM_PROMPT_ECHO_OFF:
if (pampasswd == NULL) {
free(reply);
return PAM_CONV_ERR;
}
reply[count].resp_retcode = PAM_SUCCESS;
reply[count].resp = xstrdup(pampasswd);
break;
case PAM_TEXT_INFO:
reply[count].resp_retcode = PAM_SUCCESS;
reply[count].resp = xstrdup("");
if (msg[count]->msg != NULL)
pam_msg_cat(msg[count]->msg);
break;
default:
free(reply);
return PAM_CONV_ERR;
}
}
*resp = reply;
return PAM_SUCCESS;
}
/* Called at exit to cleanly shutdown PAM */
void pam_cleanup_proc(void *context)
{
int pam_retval;
if (pamh != NULL)
{
pam_retval = pam_close_session((pam_handle_t *)pamh, 0);
if (pam_retval != PAM_SUCCESS) {
log("Cannot close PAM session: %.200s",
PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
}
pam_retval = pam_setcred((pam_handle_t *)pamh, PAM_DELETE_CRED);
if (pam_retval != PAM_SUCCESS) {
log("Cannot delete credentials: %.200s",
PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
}
pam_retval = pam_end((pam_handle_t *)pamh, pam_retval);
if (pam_retval != PAM_SUCCESS) {
log("Cannot release PAM authentication: %.200s",
PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
}
}
}
/* Attempt password authentation using PAM */
int auth_pam_password(struct passwd *pw, const char *password)
{
extern ServerOptions options;
int pam_retval;
/* deny if no user. */
if (pw == NULL)
return 0;
if (pw->pw_uid == 0 && options.permit_root_login == 2)
return 0;
if (*password == '\0' && options.permit_empty_passwd == 0)
return 0;
pampasswd = password;
pam_retval = pam_authenticate((pam_handle_t *)pamh, 0);
if (pam_retval == PAM_SUCCESS) {
debug("PAM Password authentication accepted for user \"%.100s\"",
pw->pw_name);
return 1;
} else {
debug("PAM Password authentication for \"%.100s\" failed: %s",
pw->pw_name, PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
return 0;
}
}
/* Do account management using PAM */
int do_pam_account(char *username, char *remote_user)
{
int pam_retval;
debug("PAM setting rhost to \"%.200s\"", get_canonical_hostname());
pam_retval = pam_set_item((pam_handle_t *)pamh, PAM_RHOST,
get_canonical_hostname());
if (pam_retval != PAM_SUCCESS) {
fatal("PAM set rhost failed: %.200s",
PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
}
if (remote_user != NULL) {
debug("PAM setting ruser to \"%.200s\"", remote_user);
pam_retval = pam_set_item((pam_handle_t *)pamh, PAM_RUSER, remote_user);
if (pam_retval != PAM_SUCCESS) {
fatal("PAM set ruser failed: %.200s",
PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
}
}
pam_retval = pam_acct_mgmt((pam_handle_t *)pamh, 0);
switch (pam_retval) {
case PAM_SUCCESS:
/* This is what we want */
break;
case PAM_NEW_AUTHTOK_REQD:
pam_msg_cat(NEW_AUTHTOK_MSG);
break;
default:
log("PAM rejected by account configuration: %.200s",
PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
return(0);
}
return(1);
}
/* Do PAM-specific session initialisation */
void do_pam_session(char *username, const char *ttyname)
{
int pam_retval;
if (ttyname != NULL) {
debug("PAM setting tty to \"%.200s\"", ttyname);
pam_retval = pam_set_item((pam_handle_t *)pamh, PAM_TTY, ttyname);
if (pam_retval != PAM_SUCCESS) {
fatal("PAM set tty failed: %.200s",
PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
}
}
pam_retval = pam_open_session((pam_handle_t *)pamh, 0);
if (pam_retval != PAM_SUCCESS) {
fatal("PAM session setup failed: %.200s",
PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
}
}
/* Set PAM credentials */
void do_pam_setcred()
{
int pam_retval;
debug("PAM establishing creds");
pam_retval = pam_setcred((pam_handle_t *)pamh, PAM_ESTABLISH_CRED);
if (pam_retval != PAM_SUCCESS) {
fatal("PAM setcred failed: %.200s",
PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
}
}
/* Cleanly shutdown PAM */
void finish_pam(void)
{
pam_cleanup_proc(NULL);
fatal_remove_cleanup(&pam_cleanup_proc, NULL);
}
/* Start PAM authentication for specified account */
void start_pam(struct passwd *pw)
{
int pam_retval;
debug("Starting up PAM with username \"%.200s\"", pw->pw_name);
pam_retval = pam_start(SSHD_PAM_SERVICE, pw->pw_name, &conv,
(pam_handle_t**)&pamh);
if (pam_retval != PAM_SUCCESS) {
fatal("PAM initialisation failed: %.200s",
PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
}
fatal_add_cleanup(&pam_cleanup_proc, NULL);
}
/* Return list of PAM enviornment strings */
char **fetch_pam_environment(void)
{
#ifdef HAVE_PAM_GETENVLIST
return(pam_getenvlist((pam_handle_t *)pamh));
#else /* HAVE_PAM_GETENVLIST */
return(NULL);
#endif /* HAVE_PAM_GETENVLIST */
}
/* Print any messages that have been generated during authentication */
/* or account checking to stderr */
void print_pam_messages(void)
{
if (pam_msg != NULL)
fprintf(stderr, pam_msg);
}
/* Append a message to the PAM message buffer */
void pam_msg_cat(const char *msg)
{
char *p;
size_t new_msg_len;
size_t pam_msg_len;
new_msg_len = strlen(msg);
if (pam_msg) {
pam_msg_len = strlen(pam_msg);
pam_msg = xrealloc(pam_msg, new_msg_len + pam_msg_len + 2);
p = pam_msg + pam_msg_len;
} else {
pam_msg = p = xmalloc(new_msg_len + 2);
}
memcpy(p, msg, new_msg_len);
p[new_msg_len] = '\n';
p[new_msg_len + 1] = '\0';
}
#endif /* USE_PAM */
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