blob: 08b88f0dd7d48257c3b4eecb10731e5ddf9946fe [file] [log] [blame] [raw]
/*-
* Copyright (c) 2002 Networks Associates Technology, Inc.
* All rights reserved.
*
* This software was developed for the FreeBSD Project by ThinkSec AS and
* NAI Labs, the Security Research Division of Network Associates, Inc.
* under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
* DARPA CHATS research program.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/* Based on $FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des Exp $ */
#include "includes.h"
RCSID("$Id: auth-pam.c,v 1.68 2003/08/26 01:58:16 dtucker Exp $");
#ifdef USE_PAM
#include <security/pam_appl.h>
#include "auth.h"
#include "auth-pam.h"
#include "buffer.h"
#include "bufaux.h"
#include "canohost.h"
#include "log.h"
#include "monitor_wrap.h"
#include "msg.h"
#include "packet.h"
#include "readpass.h"
#include "servconf.h"
#include "ssh2.h"
#include "xmalloc.h"
#include "auth-options.h"
extern ServerOptions options;
#define __unused
#ifdef USE_POSIX_THREADS
#include <pthread.h>
/*
* Avoid namespace clash when *not* using pthreads for systems *with*
* pthreads, which unconditionally define pthread_t via sys/types.h
* (e.g. Linux)
*/
typedef pthread_t sp_pthread_t;
#else
/*
* Simulate threads with processes.
*/
typedef pid_t sp_pthread_t;
static void
pthread_exit(void *value __unused)
{
_exit(0);
}
static int
pthread_create(sp_pthread_t *thread, const void *attr __unused,
void *(*thread_start)(void *), void *arg)
{
pid_t pid;
switch ((pid = fork())) {
case -1:
error("fork(): %s", strerror(errno));
return (-1);
case 0:
thread_start(arg);
_exit(1);
default:
*thread = pid;
return (0);
}
}
static int
pthread_cancel(sp_pthread_t thread)
{
return (kill(thread, SIGTERM));
}
static int
pthread_join(sp_pthread_t thread, void **value __unused)
{
int status;
waitpid(thread, &status, 0);
return (status);
}
#endif
static pam_handle_t *sshpam_handle;
static int sshpam_err;
static int sshpam_authenticated;
static int sshpam_new_authtok_reqd;
static int sshpam_session_open;
static int sshpam_cred_established;
struct pam_ctxt {
sp_pthread_t pam_thread;
int pam_psock;
int pam_csock;
int pam_done;
};
static void sshpam_free_ctx(void *);
/*
* Conversation function for authentication thread.
*/
static int
sshpam_thread_conv(int n, const struct pam_message **msg,
struct pam_response **resp, void *data)
{
Buffer buffer;
struct pam_ctxt *ctxt;
int i;
ctxt = data;
if (n <= 0 || n > PAM_MAX_NUM_MSG)
return (PAM_CONV_ERR);
*resp = xmalloc(n * sizeof **resp);
buffer_init(&buffer);
for (i = 0; i < n; ++i) {
resp[i]->resp_retcode = 0;
resp[i]->resp = NULL;
switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
case PAM_PROMPT_ECHO_OFF:
buffer_put_cstring(&buffer, PAM_MSG_MEMBER(msg, i, msg));
ssh_msg_send(ctxt->pam_csock,
PAM_MSG_MEMBER(msg, i, msg_style), &buffer);
ssh_msg_recv(ctxt->pam_csock, &buffer);
if (buffer_get_char(&buffer) != PAM_AUTHTOK)
goto fail;
resp[i]->resp = buffer_get_string(&buffer, NULL);
break;
case PAM_PROMPT_ECHO_ON:
buffer_put_cstring(&buffer, PAM_MSG_MEMBER(msg, i, msg));
ssh_msg_send(ctxt->pam_csock,
PAM_MSG_MEMBER(msg, i, msg_style), &buffer);
ssh_msg_recv(ctxt->pam_csock, &buffer);
if (buffer_get_char(&buffer) != PAM_AUTHTOK)
goto fail;
resp[i]->resp = buffer_get_string(&buffer, NULL);
break;
case PAM_ERROR_MSG:
buffer_put_cstring(&buffer, PAM_MSG_MEMBER(msg, i, msg));
ssh_msg_send(ctxt->pam_csock,
PAM_MSG_MEMBER(msg, i, msg_style), &buffer);
break;
case PAM_TEXT_INFO:
buffer_put_cstring(&buffer, PAM_MSG_MEMBER(msg, i, msg));
ssh_msg_send(ctxt->pam_csock,
PAM_MSG_MEMBER(msg, i, msg_style), &buffer);
break;
default:
goto fail;
}
buffer_clear(&buffer);
}
buffer_free(&buffer);
return (PAM_SUCCESS);
fail:
while (i)
xfree(resp[--i]);
xfree(*resp);
*resp = NULL;
buffer_free(&buffer);
return (PAM_CONV_ERR);
}
/*
* Authentication thread.
*/
static void *
sshpam_thread(void *ctxtp)
{
struct pam_ctxt *ctxt = ctxtp;
Buffer buffer;
struct pam_conv sshpam_conv = { sshpam_thread_conv, ctxt };
#ifndef USE_POSIX_THREADS
const char *pam_user;
pam_get_item(sshpam_handle, PAM_USER, (const void **)&pam_user);
setproctitle("%s [pam]", pam_user);
#endif
buffer_init(&buffer);
sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
(const void *)&sshpam_conv);
if (sshpam_err != PAM_SUCCESS)
goto auth_fail;
sshpam_err = pam_authenticate(sshpam_handle, 0);
if (sshpam_err != PAM_SUCCESS)
goto auth_fail;
buffer_put_cstring(&buffer, "OK");
ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
buffer_free(&buffer);
pthread_exit(NULL);
auth_fail:
buffer_put_cstring(&buffer,
pam_strerror(sshpam_handle, sshpam_err));
ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
buffer_free(&buffer);
pthread_exit(NULL);
return (NULL); /* Avoid warning for non-pthread case */
}
static void
sshpam_thread_cleanup(void *ctxtp)
{
struct pam_ctxt *ctxt = ctxtp;
pthread_cancel(ctxt->pam_thread);
pthread_join(ctxt->pam_thread, NULL);
close(ctxt->pam_psock);
close(ctxt->pam_csock);
}
static int
sshpam_null_conv(int n, const struct pam_message **msg,
struct pam_response **resp, void *data)
{
return (PAM_CONV_ERR);
}
static struct pam_conv null_conv = { sshpam_null_conv, NULL };
static void
sshpam_cleanup(void *arg)
{
(void)arg;
debug("PAM: cleanup");
pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
if (sshpam_cred_established) {
pam_setcred(sshpam_handle, PAM_DELETE_CRED);
sshpam_cred_established = 0;
}
if (sshpam_session_open) {
pam_close_session(sshpam_handle, PAM_SILENT);
sshpam_session_open = 0;
}
sshpam_authenticated = sshpam_new_authtok_reqd = 0;
pam_end(sshpam_handle, sshpam_err);
sshpam_handle = NULL;
}
static int
sshpam_init(const char *user)
{
extern u_int utmp_len;
const char *pam_rhost, *pam_user;
if (sshpam_handle != NULL) {
/* We already have a PAM context; check if the user matches */
sshpam_err = pam_get_item(sshpam_handle,
PAM_USER, (const void **)&pam_user);
if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
return (0);
fatal_remove_cleanup(sshpam_cleanup, NULL);
pam_end(sshpam_handle, sshpam_err);
sshpam_handle = NULL;
}
debug("PAM: initializing for \"%s\"", user);
sshpam_err = pam_start("sshd", user, &null_conv, &sshpam_handle);
if (sshpam_err != PAM_SUCCESS) {
pam_end(sshpam_handle, sshpam_err);
sshpam_handle = NULL;
return (-1);
}
pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
if (sshpam_err != PAM_SUCCESS) {
pam_end(sshpam_handle, sshpam_err);
sshpam_handle = NULL;
return (-1);
}
#ifdef PAM_TTY_KLUDGE
/*
* Some silly PAM modules (e.g. pam_time) require a TTY to operate.
* sshd doesn't set the tty until too late in the auth process and
* may not even set one (for tty-less connections)
*/
debug("PAM: setting PAM_TTY to \"ssh\"");
sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
if (sshpam_err != PAM_SUCCESS) {
pam_end(sshpam_handle, sshpam_err);
sshpam_handle = NULL;
return (-1);
}
#endif
fatal_add_cleanup(sshpam_cleanup, NULL);
return (0);
}
static void *
sshpam_init_ctx(Authctxt *authctxt)
{
struct pam_ctxt *ctxt;
int socks[2];
/* Refuse to start if we don't have PAM enabled */
if (!options.use_pam)
return NULL;
/* Initialize PAM */
if (sshpam_init(authctxt->user) == -1) {
error("PAM: initialization failed");
return (NULL);
}
ctxt = xmalloc(sizeof *ctxt);
ctxt->pam_done = 0;
/* Start the authentication thread */
if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
error("PAM: failed create sockets: %s", strerror(errno));
xfree(ctxt);
return (NULL);
}
ctxt->pam_psock = socks[0];
ctxt->pam_csock = socks[1];
if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
error("PAM: failed to start authentication thread: %s",
strerror(errno));
close(socks[0]);
close(socks[1]);
xfree(ctxt);
return (NULL);
}
fatal_add_cleanup(sshpam_thread_cleanup, ctxt);
return (ctxt);
}
static int
sshpam_query(void *ctx, char **name, char **info,
u_int *num, char ***prompts, u_int **echo_on)
{
Buffer buffer;
struct pam_ctxt *ctxt = ctx;
size_t plen;
u_char type;
char *msg;
size_t len;
buffer_init(&buffer);
*name = xstrdup("");
*info = xstrdup("");
*prompts = xmalloc(sizeof(char *));
**prompts = NULL;
plen = 0;
*echo_on = xmalloc(sizeof(u_int));
while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
type = buffer_get_char(&buffer);
msg = buffer_get_string(&buffer, NULL);
switch (type) {
case PAM_PROMPT_ECHO_ON:
case PAM_PROMPT_ECHO_OFF:
*num = 1;
len = plen + strlen(msg) + 1;
**prompts = xrealloc(**prompts, len);
plen += snprintf(**prompts + plen, len, "%s", msg);
**echo_on = (type == PAM_PROMPT_ECHO_ON);
xfree(msg);
return (0);
case PAM_ERROR_MSG:
case PAM_TEXT_INFO:
/* accumulate messages */
len = plen + strlen(msg) + 1;
**prompts = xrealloc(**prompts, len);
plen += snprintf(**prompts + plen, len, "%s", msg);
xfree(msg);
break;
case PAM_SUCCESS:
case PAM_AUTH_ERR:
if (**prompts != NULL) {
/* drain any accumulated messages */
#if 0 /* XXX - not compatible with privsep */
packet_start(SSH2_MSG_USERAUTH_BANNER);
packet_put_cstring(**prompts);
packet_put_cstring("");
packet_send();
packet_write_wait();
#endif
xfree(**prompts);
**prompts = NULL;
}
if (type == PAM_SUCCESS) {
*num = 0;
**echo_on = 0;
ctxt->pam_done = 1;
xfree(msg);
return (0);
}
error("PAM: %s", msg);
default:
*num = 0;
**echo_on = 0;
xfree(msg);
ctxt->pam_done = -1;
return (-1);
}
}
return (-1);
}
/* XXX - see also comment in auth-chall.c:verify_response */
static int
sshpam_respond(void *ctx, u_int num, char **resp)
{
Buffer buffer;
struct pam_ctxt *ctxt = ctx;
debug2("PAM: %s", __func__);
switch (ctxt->pam_done) {
case 1:
sshpam_authenticated = 1;
return (0);
case 0:
break;
default:
return (-1);
}
if (num != 1) {
error("PAM: expected one response, got %u", num);
return (-1);
}
buffer_init(&buffer);
buffer_put_cstring(&buffer, *resp);
ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer);
buffer_free(&buffer);
return (1);
}
static void
sshpam_free_ctx(void *ctxtp)
{
struct pam_ctxt *ctxt = ctxtp;
fatal_remove_cleanup(sshpam_thread_cleanup, ctxt);
sshpam_thread_cleanup(ctxtp);
xfree(ctxt);
/*
* We don't call sshpam_cleanup() here because we may need the PAM
* handle at a later stage, e.g. when setting up a session. It's
* still on the cleanup list, so pam_end() *will* be called before
* the server process terminates.
*/
}
KbdintDevice sshpam_device = {
"pam",
sshpam_init_ctx,
sshpam_query,
sshpam_respond,
sshpam_free_ctx
};
KbdintDevice mm_sshpam_device = {
"pam",
mm_sshpam_init_ctx,
mm_sshpam_query,
mm_sshpam_respond,
mm_sshpam_free_ctx
};
/*
* This replaces auth-pam.c
*/
void
start_pam(const char *user)
{
if (!options.use_pam)
fatal("PAM: initialisation requested when UsePAM=no");
if (sshpam_init(user) == -1)
fatal("PAM: initialisation failed");
}
void
finish_pam(void)
{
fatal_remove_cleanup(sshpam_cleanup, NULL);
sshpam_cleanup(NULL);
}
u_int
do_pam_account(void)
{
sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
debug3("%s: pam_acct_mgmt = %d", __func__, sshpam_err);
if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD)
return (0);
if (sshpam_err == PAM_NEW_AUTHTOK_REQD) {
sshpam_new_authtok_reqd = 1;
/* Prevent forwardings until password changed */
no_port_forwarding_flag |= 2;
no_agent_forwarding_flag |= 2;
no_x11_forwarding_flag |= 2;
}
return (1);
}
void
do_pam_session(const char *user, const char *tty)
{
sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
(const void *)&null_conv);
if (sshpam_err != PAM_SUCCESS)
fatal("PAM: failed to set PAM_CONV: %s",
pam_strerror(sshpam_handle, sshpam_err));
if (tty != NULL) {
debug("PAM: setting PAM_TTY to \"%s\"", tty);
sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
if (sshpam_err != PAM_SUCCESS)
fatal("PAM: failed to set PAM_TTY: %s",
pam_strerror(sshpam_handle, sshpam_err));
}
sshpam_err = pam_open_session(sshpam_handle, 0);
if (sshpam_err != PAM_SUCCESS)
fatal("PAM: pam_open_session(): %s",
pam_strerror(sshpam_handle, sshpam_err));
sshpam_session_open = 1;
}
void
do_pam_setcred(int init)
{
sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
(const void *)&null_conv);
if (sshpam_err != PAM_SUCCESS)
fatal("PAM: failed to set PAM_CONV: %s",
pam_strerror(sshpam_handle, sshpam_err));
if (init) {
debug("PAM: establishing credentials");
sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
} else {
debug("PAM: reinitializing credentials");
sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
}
if (sshpam_err == PAM_SUCCESS) {
sshpam_cred_established = 1;
return;
}
if (sshpam_authenticated)
fatal("PAM: pam_setcred(): %s",
pam_strerror(sshpam_handle, sshpam_err));
else
debug("PAM: pam_setcred(): %s",
pam_strerror(sshpam_handle, sshpam_err));
}
int
is_pam_password_change_required(void)
{
return (sshpam_new_authtok_reqd);
}
static int
pam_chauthtok_conv(int n, const struct pam_message **msg,
struct pam_response **resp, void *data)
{
char input[PAM_MAX_MSG_SIZE];
int i;
if (n <= 0 || n > PAM_MAX_NUM_MSG)
return (PAM_CONV_ERR);
*resp = xmalloc(n * sizeof **resp);
for (i = 0; i < n; ++i) {
switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
case PAM_PROMPT_ECHO_OFF:
resp[i]->resp =
read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
RP_ALLOW_STDIN);
resp[i]->resp_retcode = PAM_SUCCESS;
break;
case PAM_PROMPT_ECHO_ON:
fputs(PAM_MSG_MEMBER(msg, i, msg), stderr);
fgets(input, sizeof input, stdin);
resp[i]->resp = xstrdup(input);
resp[i]->resp_retcode = PAM_SUCCESS;
break;
case PAM_ERROR_MSG:
case PAM_TEXT_INFO:
fputs(PAM_MSG_MEMBER(msg, i, msg), stderr);
resp[i]->resp_retcode = PAM_SUCCESS;
break;
default:
goto fail;
}
}
return (PAM_SUCCESS);
fail:
while (i)
xfree(resp[--i]);
xfree(*resp);
*resp = NULL;
return (PAM_CONV_ERR);
}
/*
* XXX this should be done in the authentication phase, but ssh1 doesn't
* support that
*/
void
do_pam_chauthtok(void)
{
struct pam_conv pam_conv = { pam_chauthtok_conv, NULL };
if (use_privsep)
fatal("Password expired (unable to change with privsep)");
sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
(const void *)&pam_conv);
if (sshpam_err != PAM_SUCCESS)
fatal("PAM: failed to set PAM_CONV: %s",
pam_strerror(sshpam_handle, sshpam_err));
debug("PAM: changing password");
sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
if (sshpam_err != PAM_SUCCESS)
fatal("PAM: pam_chauthtok(): %s",
pam_strerror(sshpam_handle, sshpam_err));
}
/*
* Set a PAM environment string. We need to do this so that the session
* modules can handle things like Kerberos/GSI credentials that appear
* during the ssh authentication process.
*/
int
do_pam_putenv(char *name, char *value)
{
char *compound;
int ret = 1;
#ifdef HAVE_PAM_PUTENV
compound = xmalloc(strlen(name)+strlen(value)+2);
if (compound) {
sprintf(compound,"%s=%s",name,value);
ret = pam_putenv(sshpam_handle,compound);
xfree(compound);
}
#endif
return (ret);
}
void
print_pam_messages(void)
{
/* XXX */
}
char **
fetch_pam_environment(void)
{
#ifdef HAVE_PAM_GETENVLIST
debug("PAM: retrieving environment");
return (pam_getenvlist(sshpam_handle));
#else
return (NULL);
#endif
}
void
free_pam_environment(char **env)
{
char **envp;
if (env == NULL)
return;
for (envp = env; *envp; envp++)
xfree(*envp);
xfree(env);
}
#endif /* USE_PAM */