/* CRAM-MD5 SASL plugin
* Rob Siemborski
* Tim Martin
* $Id: cram.c,v 1.85 2004/09/08 10:57:56 mel Exp $
*/
/*
* Copyright (c) 1998-2003 Carnegie Mellon University. All rights reserved.
*
* 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.
*
* 3. The name "Carnegie Mellon University" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For permission or any other legal
* details, please contact
* Office of Technology Transfer
* Carnegie Mellon University
* 5000 Forbes Avenue
* Pittsburgh, PA 15213-3890
* (412) 268-4387, fax: (412) 268-7395
* tech-transfer@andrew.cmu.edu
*
* 4. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by Computing Services
* at Carnegie Mellon University (http://www.cmu.edu/computing/)."
*
* CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
* THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
* FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
* AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <config.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#ifndef macintosh
#include <sys/stat.h>
#endif
#include <fcntl.h>
#include <sasl.h>
#include <saslplug.h>
#include <saslutil.h>
#include "plugin_common.h"
#ifdef macintosh
#include <sasl_cram_plugin_decl.h>
#endif
/***************************** Common Section *****************************/
static const char plugin_id[] = "$Id: cram.c,v 1.85 2004/09/08 10:57:56 mel Exp $";
/* convert a string of 8bit chars to it's representation in hex
* using lowercase letters
*/
static char *convert16(unsigned char *in, int inlen, const sasl_utils_t *utils)
{
static char hex[]="0123456789abcdef";
int lup;
char *out;
out = utils->malloc(inlen*2+1);
if (out == NULL) return NULL;
for (lup=0; lup < inlen; lup++) {
out[lup*2] = hex[in[lup] >> 4];
out[lup*2+1] = hex[in[lup] & 15];
}
out[lup*2] = 0;
return out;
}
/***************************** Server Section *****************************/
typedef struct server_context {
int state;
char *challenge;
} server_context_t;
static int
crammd5_server_mech_new(void *glob_context __attribute__((unused)),
sasl_server_params_t *sparams,
const char *challenge __attribute__((unused)),
unsigned challen __attribute__((unused)),
void **conn_context)
{
server_context_t *text;
/* holds state are in */
text = sparams->utils->malloc(sizeof(server_context_t));
if (text == NULL) {
MEMERROR( sparams->utils );
return SASL_NOMEM;
}
memset(text, 0, sizeof(server_context_t));
text->state = 1;
*conn_context = text;
return SASL_OK;
}
/*
* Returns the current time (or part of it) in string form
* maximum length=15
*/
static char *gettime(sasl_server_params_t *sparams)
{
char *ret;
time_t t;
t=time(NULL);
ret= sparams->utils->malloc(15);
if (ret==NULL) return NULL;
/* the bottom bits are really the only random ones so if
we overflow we don't want to loose them */
snprintf(ret,15,"%lu",t%(0xFFFFFF));
return ret;
}
static char *randomdigits(sasl_server_params_t *sparams)
{
unsigned int num;
char *ret;
unsigned char temp[5]; /* random 32-bit number */
sparams->utils->rand(sparams->utils->rpool,(char *) temp,4);
num=(temp[0] * 256 * 256 * 256) +
(temp[1] * 256 * 256) +
(temp[2] * 256) +
(temp[3] );
ret = sparams->utils->malloc(15); /* there's no way an unsigned can be longer than this right? */
if (ret == NULL) return NULL;
sprintf(ret, "%u", num);
return ret;
}
static int
crammd5_server_mech_step1(server_context_t *text,
sasl_server_params_t *sparams,
const char *clientin __attribute__((unused)),
unsigned clientinlen,
const char **serverout,
unsigned *serveroutlen,
sasl_out_params_t *oparams __attribute__((unused)))
{
char *time, *randdigits;
/* we shouldn't have received anything */
if (clientinlen != 0) {
SETERROR(sparams->utils, "CRAM-MD5 does not accpet inital data");
return SASL_BADPROT;
}
/* get time and a random number for the nonce */
time = gettime(sparams);
randdigits = randomdigits(sparams);
if ((time == NULL) || (randdigits == NULL)) {
MEMERROR( sparams->utils );
return SASL_NOMEM;
}
/* allocate some space for the challenge */
text->challenge = sparams->utils->malloc(200 + 1);
if (text->challenge == NULL) {
MEMERROR(sparams->utils);
return SASL_NOMEM;
}
/* create the challenge */
snprintf(text->challenge, 200, "<%s.%s@%s>", randdigits, time,
sparams->serverFQDN);
*serverout = text->challenge;
*serveroutlen = (unsigned) strlen(text->challenge);
/* free stuff */
sparams->utils->free(time);
sparams->utils->free(randdigits);
text->state = 2;
return SASL_CONTINUE;
}
static int
crammd5_server_mech_step2(server_context_t *text,
sasl_server_params_t *sparams,
const char *clientin,
unsigned clientinlen,
const char **serverout __attribute__((unused)),
unsigned *serveroutlen __attribute__((unused)),
sasl_out_params_t *oparams)
{
char *userid = NULL;
sasl_secret_t *sec = NULL;
int pos;
size_t len;
int result = SASL_FAIL;
const char *password_request[] = { SASL_AUX_PASSWORD,
"*cmusaslsecretCRAM-MD5",
NULL };
struct propval auxprop_values[3];
HMAC_MD5_CTX tmphmac;
HMAC_MD5_STATE md5state;
int clear_md5state = 0;
char *digest_str = NULL;
UINT4 digest[4];
/* extract userid; everything before last space */
pos = clientinlen-1;
while ((pos > 0) && (clientin[pos] != ' ')) pos--;
if (pos <= 0) {
SETERROR( sparams->utils,"need authentication name");
return SASL_BADPROT;
}
userid = (char *) sparams->utils->malloc(pos+1);
if (userid == NULL) {
MEMERROR( sparams->utils);
return SASL_NOMEM;
}
/* copy authstr out */
memcpy(userid, clientin, pos);
userid[pos] = '\0';
result = sparams->utils->prop_request(sparams->propctx, password_request);
if (result != SASL_OK) goto done;
/* this will trigger the getting of the aux properties */
result = sparams->canon_user(sparams->utils->conn,
userid, 0, SASL_CU_AUTHID | SASL_CU_AUTHZID,
oparams);
if (result != SASL_OK) goto done;
result = sparams->utils->prop_getnames(sparams->propctx,
password_request,
auxprop_values);
if (result < 0 ||
((!auxprop_values[0].name || !auxprop_values[0].values) &&
(!auxprop_values[1].name || !auxprop_values[1].values))) {
/* We didn't find this username */
sparams->utils->seterror(sparams->utils->conn,0,
"no secret in database");
result = sparams->transition ? SASL_TRANS : SASL_NOUSER;
goto done;
}
if (auxprop_values[0].name && auxprop_values[0].values) {
len = strlen(auxprop_values[0].values[0]);
if (len == 0) {
sparams->utils->seterror(sparams->utils->conn,0,
"empty secret");
result = SASL_FAIL;
goto done;
}
sec = sparams->utils->malloc(sizeof(sasl_secret_t) + len);
if (!sec) goto done;
sec->len = (unsigned) len;
strncpy((char *)sec->data, auxprop_values[0].values[0], len + 1);
clear_md5state = 1;
/* Do precalculation on plaintext secret */
sparams->utils->hmac_md5_precalc(&md5state, /* OUT */
sec->data,
sec->len);
} else if (auxprop_values[1].name && auxprop_values[1].values) {
/* We have a precomputed secret */
memcpy(&md5state, auxprop_values[1].values[0],
sizeof(HMAC_MD5_STATE));
} else {
sparams->utils->seterror(sparams->utils->conn, 0,
"Have neither type of secret");
return SASL_FAIL;
}
/* erase the plaintext password */
sparams->utils->prop_erase(sparams->propctx, password_request[0]);
/* ok this is annoying:
so we have this half-way hmac transform instead of the plaintext
that means we half to:
-import it back into a md5 context
-do an md5update with the nonce
-finalize it
*/
sparams->utils->hmac_md5_import(&tmphmac, (HMAC_MD5_STATE *) &md5state);
sparams->utils->MD5Update(&(tmphmac.ictx),
(const unsigned char *) text->challenge,
(unsigned) strlen(text->challenge));
sparams->utils->hmac_md5_final((unsigned char *) &digest, &tmphmac);
/* convert to base 16 with lower case letters */
digest_str = convert16((unsigned char *) digest, 16, sparams->utils);
/* if same then verified
* - we know digest_str is null terminated but clientin might not be
* - verify the length of clientin anyway!
*/
len = strlen(digest_str);
if (clientinlen-pos-1 < len ||
strncmp(digest_str, clientin+pos+1, len) != 0) {
sparams->utils->seterror(sparams->utils->conn, 0,
"incorrect digest response");
result = SASL_BADAUTH;
goto done;
}
/* set oparams */
oparams->doneflag = 1;
oparams->mech_ssf = 0;
oparams->maxoutbuf = 0;
oparams->encode_context = NULL;
oparams->encode = NULL;
oparams->decode_context = NULL;
oparams->decode = NULL;
oparams->param_version = 0;
result = SASL_OK;
done:
if (userid) sparams->utils->free(userid);
if (sec) _plug_free_secret(sparams->utils, &sec);
if (digest_str) sparams->utils->free(digest_str);
if (clear_md5state) memset(&md5state, 0, sizeof(md5state));
return result;
}
static int crammd5_server_mech_step(void *conn_context,
sasl_server_params_t *sparams,
const char *clientin,
unsigned clientinlen,
const char **serverout,
unsigned *serveroutlen,
sasl_out_params_t *oparams)
{
server_context_t *text = (server_context_t *) conn_context;
*serverout = NULL;
*serveroutlen = 0;
/* this should be well more than is ever needed */
if (clientinlen > 1024) {
SETERROR(sparams->utils, "CRAM-MD5 input longer than 1024 bytes");
return SASL_BADPROT;
}
switch (text->state) {
case 1:
return crammd5_server_mech_step1(text, sparams,
clientin, clientinlen,
serverout, serveroutlen,
oparams);
case 2:
return crammd5_server_mech_step2(text, sparams,
clientin, clientinlen,
serverout, serveroutlen,
oparams);
default: /* should never get here */
sparams->utils->log(NULL, SASL_LOG_ERR,
"Invalid CRAM-MD5 server step %d\n", text->state);
return SASL_FAIL;
}
return SASL_FAIL; /* should never get here */
}
static void crammd5_server_mech_dispose(void *conn_context,
const sasl_utils_t *utils)
{
server_context_t *text = (server_context_t *) conn_context;
if (!text) return;
if (text->challenge) _plug_free_string(utils,&(text->challenge));
utils->free(text);
}
static sasl_server_plug_t crammd5_server_plugins[] =
{
{
"CRAM-MD5", /* mech_name */
0, /* max_ssf */
SASL_SEC_NOPLAINTEXT
| SASL_SEC_NOANONYMOUS, /* security_flags */
SASL_FEAT_SERVER_FIRST, /* features */
NULL, /* glob_context */
&crammd5_server_mech_new, /* mech_new */
&crammd5_server_mech_step, /* mech_step */
&crammd5_server_mech_dispose, /* mech_dispose */
NULL, /* mech_free */
NULL, /* setpass */
NULL, /* user_query */
NULL, /* idle */
NULL, /* mech avail */
NULL /* spare */
}
};
int crammd5_server_plug_init(const sasl_utils_t *utils,
int maxversion,
int *out_version,
sasl_server_plug_t **pluglist,
int *plugcount)
{
if (maxversion < SASL_SERVER_PLUG_VERSION) {
SETERROR( utils, "CRAM version mismatch");
return SASL_BADVERS;
}
*out_version = SASL_SERVER_PLUG_VERSION;
*pluglist = crammd5_server_plugins;
*plugcount = 1;
return SASL_OK;
}
/***************************** Client Section *****************************/
typedef struct client_context {
char *out_buf;
unsigned out_buf_len;
} client_context_t;
static int crammd5_client_mech_new(void *glob_context __attribute__((unused)),
sasl_client_params_t *params,
void **conn_context)
{
client_context_t *text;
/* holds state are in */
text = params->utils->malloc(sizeof(client_context_t));
if (text == NULL) {
MEMERROR(params->utils);
return SASL_NOMEM;
}
memset(text, 0, sizeof(client_context_t));
*conn_context = text;
return SASL_OK;
}
static char *make_hashed(sasl_secret_t *sec, char *nonce, int noncelen,
const sasl_utils_t *utils)
{
unsigned char digest[24];
char *in16;
if (sec == NULL) return NULL;
/* do the hmac md5 hash output 128 bits */
utils->hmac_md5((unsigned char *) nonce, noncelen,
sec->data, sec->len, digest);
/* convert that to hex form */
in16 = convert16(digest, 16, utils);
if (in16 == NULL) return NULL;
return in16;
}
static int crammd5_client_mech_step(void *conn_context,
sasl_client_params_t *params,
const char *serverin,
unsigned serverinlen,
sasl_interact_t **prompt_need,
const char **clientout,
unsigned *clientoutlen,
sasl_out_params_t *oparams)
{
client_context_t *text = (client_context_t *) conn_context;
const char *authid = NULL;
sasl_secret_t *password = NULL;
unsigned int free_password = 0; /* set if we need to free password */
int auth_result = SASL_OK;
int pass_result = SASL_OK;
int result;
size_t maxsize;
char *in16 = NULL;
*clientout = NULL;
*clientoutlen = 0;
/* First check for absurd lengths */
if (serverinlen > 1024) {
params->utils->seterror(params->utils->conn, 0,
"CRAM-MD5 input longer than 1024 bytes");
return SASL_BADPROT;
}
/* check if sec layer strong enough */
if (params->props.min_ssf > params->external_ssf) {
SETERROR( params->utils, "SSF requested of CRAM-MD5 plugin");
return SASL_TOOWEAK;
}
/* try to get the userid */
if (oparams->authid == NULL) {
auth_result=_plug_get_authid(params->utils, &authid, prompt_need);
if ((auth_result != SASL_OK) && (auth_result != SASL_INTERACT))
return auth_result;
}
/* try to get the password */
if (password == NULL) {
pass_result=_plug_get_password(params->utils, &password,
&free_password, prompt_need);
if ((pass_result != SASL_OK) && (pass_result != SASL_INTERACT))
return pass_result;
}
/* free prompts we got */
if (prompt_need && *prompt_need) {
params->utils->free(*prompt_need);
*prompt_need = NULL;
}
/* if there are prompts not filled in */
if ((auth_result == SASL_INTERACT) || (pass_result == SASL_INTERACT)) {
/* make the prompt list */
result =
_plug_make_prompts(params->utils, prompt_need,
NULL, NULL,
auth_result == SASL_INTERACT ?
"Please enter your authentication name" : NULL,
NULL,
pass_result == SASL_INTERACT ?
"Please enter your password" : NULL, NULL,
NULL, NULL, NULL,
NULL, NULL, NULL);
if (result != SASL_OK) goto cleanup;
return SASL_INTERACT;
}
if (!password) {
PARAMERROR(params->utils);
return SASL_BADPARAM;
}
result = params->canon_user(params->utils->conn, authid, 0,
SASL_CU_AUTHID | SASL_CU_AUTHZID, oparams);
if (result != SASL_OK) goto cleanup;
/*
* username SP digest (keyed md5 where key is passwd)
*/
in16 = make_hashed(password, (char *) serverin, serverinlen,
params->utils);
if (in16 == NULL) {
SETERROR(params->utils, "whoops, make_hashed failed us this time");
result = SASL_FAIL;
goto cleanup;
}
maxsize = 32+1+strlen(oparams->authid)+30;
result = _plug_buf_alloc(params->utils, &(text->out_buf),
&(text->out_buf_len), (unsigned) maxsize);
if (result != SASL_OK) goto cleanup;
snprintf(text->out_buf, maxsize, "%s %s", oparams->authid, in16);
*clientout = text->out_buf;
*clientoutlen = (unsigned) strlen(*clientout);
/* set oparams */
oparams->doneflag = 1;
oparams->mech_ssf = 0;
oparams->maxoutbuf = 0;
oparams->encode_context = NULL;
oparams->encode = NULL;
oparams->decode_context = NULL;
oparams->decode = NULL;
oparams->param_version = 0;
result = SASL_OK;
cleanup:
/* get rid of private information */
if (in16) _plug_free_string(params->utils, &in16);
/* get rid of all sensitive info */
if (free_password) _plug_free_secret(params-> utils, &password);
return result;
}
static void crammd5_client_mech_dispose(void *conn_context,
const sasl_utils_t *utils)
{
client_context_t *text = (client_context_t *) conn_context;
if (!text) return;
if (text->out_buf) utils->free(text->out_buf);
utils->free(text);
}
static sasl_client_plug_t crammd5_client_plugins[] =
{
{
"CRAM-MD5", /* mech_name */
0, /* max_ssf */
SASL_SEC_NOPLAINTEXT
| SASL_SEC_NOANONYMOUS, /* security_flags */
SASL_FEAT_SERVER_FIRST, /* features */
NULL, /* required_prompts */
NULL, /* glob_context */
&crammd5_client_mech_new, /* mech_new */
&crammd5_client_mech_step, /* mech_step */
&crammd5_client_mech_dispose, /* mech_dispose */
NULL, /* mech_free */
NULL, /* idle */
NULL, /* spare */
NULL /* spare */
}
};
int crammd5_client_plug_init(const sasl_utils_t *utils,
int maxversion,
int *out_version,
sasl_client_plug_t **pluglist,
int *plugcount)
{
if (maxversion < SASL_CLIENT_PLUG_VERSION) {
SETERROR( utils, "CRAM version mismatch");
return SASL_BADVERS;
}
*out_version = SASL_CLIENT_PLUG_VERSION;
*pluglist = crammd5_client_plugins;
*plugcount = 1;
return SASL_OK;
}
