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curl/lib/curl_sasl.c
Daniel Stenberg 365c5ba395 formpost: better random boundaries 
When doing multi-part formposts, libcurl used a pseudo-random value that
was seeded with time(). This turns out to be bad for users who formpost
data that is provided with users who then can guess how the boundary
string will look like and then they can forge a different formpost part
and trick the receiver.

My advice to such implementors is (still even after this change) to not
rely on the boundary strings being cryptographically strong. Fix your
code and logic to not depend on them that much!

I moved the Curl_rand() function into the sslgen.c source file now to be
able to take advantage of the SSL library's random function if it
provides one. If not, try to use the RANDOM_FILE for seeding and as a
last resort keep the old logic, just modified to also add microseconds
which makes it harder to properly guess the exact seed.

The formboundary() function in formdata.c is now using 64 bit entropy
for the boundary and therefore the string of dashes was reduced by 4
letters and there are 16 hex digits following it. The total length is
thus still the same.

Bug: http://curl.haxx.se/bug/view.cgi?id=1251
Reported-by: "Floris"
2013-06-25 09:55:49 +02:00

498 lines
16 KiB
C
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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 2012 - 2013, Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at http://curl.haxx.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
* RFC2195 CRAM-MD5 authentication
* RFC2831 DIGEST-MD5 authentication
* RFC4422 Simple Authentication and Security Layer (SASL)
* RFC4616 PLAIN authentication
*
***************************************************************************/
#include "curl_setup.h"
#include <curl/curl.h>
#include "urldata.h"
#include "curl_base64.h"
#include "curl_md5.h"
#include "sslgen.h"
#include "curl_hmac.h"
#include "curl_ntlm_msgs.h"
#include "curl_sasl.h"
#include "warnless.h"
#include "curl_memory.h"
#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>
/* The last #include file should be: */
#include "memdebug.h"
#ifndef CURL_DISABLE_CRYPTO_AUTH
/* Retrieves the value for a corresponding key from the challenge string
* returns TRUE if the key could be found, FALSE if it does not exists
*/
static bool sasl_digest_get_key_value(const unsigned char *chlg,
const char *key,
char *value,
size_t max_val_len,
char end_char)
{
char *find_pos;
size_t i;
find_pos = strstr((const char *) chlg, key);
if(!find_pos)
return FALSE;
find_pos += strlen(key);
for(i = 0; *find_pos && *find_pos != end_char && i < max_val_len - 1; ++i)
value[i] = *find_pos++;
value[i] = '\0';
return TRUE;
}
#endif
/*
* Curl_sasl_create_plain_message()
*
* This is used to generate an already encoded PLAIN message ready
* for sending to the recipient.
*
* Parameters:
*
* data [in] - The session handle.
* userp [in] - The user name.
* passdwp [in] - The user's password.
* outptr [in/out] - The address where a pointer to newly allocated memory
* holding the result will be stored upon completion.
* outlen [out] - The length of the output message.
*
* Returns CURLE_OK on success.
*/
CURLcode Curl_sasl_create_plain_message(struct SessionHandle *data,
const char *userp,
const char *passwdp,
char **outptr, size_t *outlen)
{
char plainauth[2 * MAX_CURL_USER_LENGTH + MAX_CURL_PASSWORD_LENGTH];
size_t ulen;
size_t plen;
ulen = strlen(userp);
plen = strlen(passwdp);
if(2 * ulen + plen + 2 > sizeof(plainauth)) {
*outlen = 0;
*outptr = NULL;
/* Plainauth too small */
return CURLE_OUT_OF_MEMORY;
}
/* Calculate the reply */
memcpy(plainauth, userp, ulen);
plainauth[ulen] = '\0';
memcpy(plainauth + ulen + 1, userp, ulen);
plainauth[2 * ulen + 1] = '\0';
memcpy(plainauth + 2 * ulen + 2, passwdp, plen);
/* Base64 encode the reply */
return Curl_base64_encode(data, plainauth, 2 * ulen + plen + 2, outptr,
outlen);
}
/*
* Curl_sasl_create_login_message()
*
* This is used to generate an already encoded LOGIN message containing the
* user name or password ready for sending to the recipient.
*
* Parameters:
*
* data [in] - The session handle.
* valuep [in] - The user name or user's password.
* outptr [in/out] - The address where a pointer to newly allocated memory
* holding the result will be stored upon completion.
* outlen [out] - The length of the output message.
*
* Returns CURLE_OK on success.
*/
CURLcode Curl_sasl_create_login_message(struct SessionHandle *data,
const char *valuep, char **outptr,
size_t *outlen)
{
size_t vlen = strlen(valuep);
if(!vlen) {
/* Calculate an empty reply */
*outptr = strdup("=");
if(*outptr) {
*outlen = (size_t) 1;
return CURLE_OK;
}
*outlen = 0;
return CURLE_OUT_OF_MEMORY;
}
/* Base64 encode the value */
return Curl_base64_encode(data, valuep, vlen, outptr, outlen);
}
#ifndef CURL_DISABLE_CRYPTO_AUTH
/*
* Curl_sasl_create_cram_md5_message()
*
* This is used to generate an already encoded CRAM-MD5 response message ready
* for sending to the recipient.
*
* Parameters:
*
* data [in] - The session handle.
* chlg64 [in] - Pointer to the base64 encoded challenge buffer.
* userp [in] - The user name.
* passdwp [in] - The user's password.
* outptr [in/out] - The address where a pointer to newly allocated memory
* holding the result will be stored upon completion.
* outlen [out] - The length of the output message.
*
* Returns CURLE_OK on success.
*/
CURLcode Curl_sasl_create_cram_md5_message(struct SessionHandle *data,
const char *chlg64,
const char *userp,
const char *passwdp,
char **outptr, size_t *outlen)
{
CURLcode result = CURLE_OK;
size_t chlg64len = strlen(chlg64);
unsigned char *chlg = (unsigned char *) NULL;
size_t chlglen = 0;
HMAC_context *ctxt;
unsigned char digest[MD5_DIGEST_LEN];
char response[MAX_CURL_USER_LENGTH + 2 * MD5_DIGEST_LEN + 1];
/* Decode the challenge if necessary */
if(chlg64len && *chlg64 != '=') {
result = Curl_base64_decode(chlg64, &chlg, &chlglen);
if(result)
return result;
}
/* Compute the digest using the password as the key */
ctxt = Curl_HMAC_init(Curl_HMAC_MD5,
(const unsigned char *) passwdp,
curlx_uztoui(strlen(passwdp)));
if(!ctxt) {
Curl_safefree(chlg);
return CURLE_OUT_OF_MEMORY;
}
/* Update the digest with the given challenge */
if(chlglen > 0)
Curl_HMAC_update(ctxt, chlg, curlx_uztoui(chlglen));
Curl_safefree(chlg);
/* Finalise the digest */
Curl_HMAC_final(ctxt, digest);
/* Prepare the response */
snprintf(response, sizeof(response),
"%s %02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
userp, digest[0], digest[1], digest[2], digest[3], digest[4],
digest[5], digest[6], digest[7], digest[8], digest[9], digest[10],
digest[11], digest[12], digest[13], digest[14], digest[15]);
/* Base64 encode the reply */
return Curl_base64_encode(data, response, 0, outptr, outlen);
}
/*
* Curl_sasl_create_digest_md5_message()
*
* This is used to generate an already encoded DIGEST-MD5 response message
* ready for sending to the recipient.
*
* Parameters:
*
* data [in] - The session handle.
* chlg64 [in] - Pointer to the base64 encoded challenge buffer.
* userp [in] - The user name.
* passdwp [in] - The user's password.
* service [in] - The service type such as www, smtp or pop
* outptr [in/out] - The address where a pointer to newly allocated memory
* holding the result will be stored upon completion.
* outlen [out] - The length of the output message.
*
* Returns CURLE_OK on success.
*/
CURLcode Curl_sasl_create_digest_md5_message(struct SessionHandle *data,
const char *chlg64,
const char *userp,
const char *passwdp,
const char *service,
char **outptr, size_t *outlen)
{
static const char table16[] = "0123456789abcdef";
CURLcode result = CURLE_OK;
unsigned char *chlg = (unsigned char *) NULL;
size_t chlglen = 0;
size_t i;
MD5_context *ctxt;
unsigned char digest[MD5_DIGEST_LEN];
char HA1_hex[2 * MD5_DIGEST_LEN + 1];
char HA2_hex[2 * MD5_DIGEST_LEN + 1];
char resp_hash_hex[2 * MD5_DIGEST_LEN + 1];
char nonce[64];
char realm[128];
char alg[64];
char nonceCount[] = "00000001";
char cnonce[] = "12345678"; /* will be changed */
char method[] = "AUTHENTICATE";
char qop[] = "auth";
char uri[128];
char response[512];
result = Curl_base64_decode(chlg64, &chlg, &chlglen);
if(result)
return result;
if(!chlg)
return CURLE_LOGIN_DENIED;
/* Retrieve nonce string from the challenge */
if(!sasl_digest_get_key_value(chlg, "nonce=\"", nonce,
sizeof(nonce), '\"')) {
Curl_safefree(chlg);
return CURLE_LOGIN_DENIED;
}
/* Retrieve realm string from the challenge */
if(!sasl_digest_get_key_value(chlg, "realm=\"", realm,
sizeof(realm), '\"')) {
/* Challenge does not have a realm, set empty string [RFC2831] page 6 */
strcpy(realm, "");
}
/* Retrieve algorithm string from the challenge */
if(!sasl_digest_get_key_value(chlg, "algorithm=", alg, sizeof(alg), ',')) {
Curl_safefree(chlg);
return CURLE_LOGIN_DENIED;
}
Curl_safefree(chlg);
/* We do not support other algorithms */
if(strcmp(alg, "md5-sess") != 0)
return CURLE_LOGIN_DENIED;
/* Generate 64 bits of random data */
for(i = 0; i < 8; i++)
cnonce[i] = table16[Curl_rand(data)%16];
/* So far so good, now calculate A1 and H(A1) according to RFC 2831 */
ctxt = Curl_MD5_init(Curl_DIGEST_MD5);
if(!ctxt)
return CURLE_OUT_OF_MEMORY;
Curl_MD5_update(ctxt, (const unsigned char *) userp,
curlx_uztoui(strlen(userp)));
Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
Curl_MD5_update(ctxt, (const unsigned char *) realm,
curlx_uztoui(strlen(realm)));
Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
Curl_MD5_update(ctxt, (const unsigned char *) passwdp,
curlx_uztoui(strlen(passwdp)));
Curl_MD5_final(ctxt, digest);
ctxt = Curl_MD5_init(Curl_DIGEST_MD5);
if(!ctxt)
return CURLE_OUT_OF_MEMORY;
Curl_MD5_update(ctxt, (const unsigned char *) digest, MD5_DIGEST_LEN);
Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
Curl_MD5_update(ctxt, (const unsigned char *) nonce,
curlx_uztoui(strlen(nonce)));
Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
Curl_MD5_update(ctxt, (const unsigned char *) cnonce,
curlx_uztoui(strlen(cnonce)));
Curl_MD5_final(ctxt, digest);
/* Convert calculated 16 octet hex into 32 bytes string */
for(i = 0; i < MD5_DIGEST_LEN; i++)
snprintf(&HA1_hex[2 * i], 3, "%02x", digest[i]);
/* Prepare the URL string */
snprintf(uri, sizeof(uri), "%s/%s", service, realm);
/* Calculate H(A2) */
ctxt = Curl_MD5_init(Curl_DIGEST_MD5);
if(!ctxt)
return CURLE_OUT_OF_MEMORY;
Curl_MD5_update(ctxt, (const unsigned char *) method,
curlx_uztoui(strlen(method)));
Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
Curl_MD5_update(ctxt, (const unsigned char *) uri,
curlx_uztoui(strlen(uri)));
Curl_MD5_final(ctxt, digest);
for(i = 0; i < MD5_DIGEST_LEN; i++)
snprintf(&HA2_hex[2 * i], 3, "%02x", digest[i]);
/* Now calculate the response hash */
ctxt = Curl_MD5_init(Curl_DIGEST_MD5);
if(!ctxt)
return CURLE_OUT_OF_MEMORY;
Curl_MD5_update(ctxt, (const unsigned char *) HA1_hex, 2 * MD5_DIGEST_LEN);
Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
Curl_MD5_update(ctxt, (const unsigned char *) nonce,
curlx_uztoui(strlen(nonce)));
Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
Curl_MD5_update(ctxt, (const unsigned char *) nonceCount,
curlx_uztoui(strlen(nonceCount)));
Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
Curl_MD5_update(ctxt, (const unsigned char *) cnonce,
curlx_uztoui(strlen(cnonce)));
Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
Curl_MD5_update(ctxt, (const unsigned char *) qop,
curlx_uztoui(strlen(qop)));
Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
Curl_MD5_update(ctxt, (const unsigned char *) HA2_hex, 2 * MD5_DIGEST_LEN);
Curl_MD5_final(ctxt, digest);
for(i = 0; i < MD5_DIGEST_LEN; i++)
snprintf(&resp_hash_hex[2 * i], 3, "%02x", digest[i]);
snprintf(response, sizeof(response),
"username=\"%s\",realm=\"%s\",nonce=\"%s\","
"cnonce=\"%s\",nc=\"%s\",digest-uri=\"%s\",response=%s",
userp, realm, nonce,
cnonce, nonceCount, uri, resp_hash_hex);
/* Base64 encode the reply */
return Curl_base64_encode(data, response, 0, outptr, outlen);
}
#endif
#ifdef USE_NTLM
/*
* Curl_sasl_create_ntlm_type1_message()
*
* This is used to generate an already encoded NTLM type-1 message ready for
* sending to the recipient.
*
* Note: This is a simple wrapper of the NTLM function which means that any
* SASL based protocols don't have to include the NTLM functions directly.
*
* Parameters:
*
* userp [in] - The user name in the format User or Domain\User.
* passdwp [in] - The user's password.
* ntlm [in/out] - The ntlm data struct being used and modified.
* outptr [in/out] - The address where a pointer to newly allocated memory
* holding the result will be stored upon completion.
* outlen [out] - The length of the output message.
*
* Returns CURLE_OK on success.
*/
CURLcode Curl_sasl_create_ntlm_type1_message(const char *userp,
const char *passwdp,
struct ntlmdata *ntlm,
char **outptr, size_t *outlen)
{
return Curl_ntlm_create_type1_message(userp, passwdp, ntlm, outptr,
outlen);
}
/*
* Curl_sasl_create_ntlm_type3_message()
*
* This is used to generate an already encoded NTLM type-3 message ready for
* sending to the recipient.
*
* Parameters:
*
* data [in] - Pointer to session handle.
* header [in] - Pointer to the base64 encoded type-2 message buffer.
* userp [in] - The user name in the format User or Domain\User.
* passdwp [in] - The user's password.
* ntlm [in/out] - The ntlm data struct being used and modified.
* outptr [in/out] - The address where a pointer to newly allocated memory
* holding the result will be stored upon completion.
* outlen [out] - The length of the output message.
*
* Returns CURLE_OK on success.
*/
CURLcode Curl_sasl_create_ntlm_type3_message(struct SessionHandle *data,
const char *header,
const char *userp,
const char *passwdp,
struct ntlmdata *ntlm,
char **outptr, size_t *outlen)
{
CURLcode result = Curl_ntlm_decode_type2_message(data, header, ntlm);
if(!result)
result = Curl_ntlm_create_type3_message(data, userp, passwdp, ntlm,
outptr, outlen);
return result;
}
#endif /* USE_NTLM */
/*
* Curl_sasl_cleanup()
*
* This is used to cleanup any libraries or curl modules used by the sasl
* functions.
*
* Parameters:
*
* conn [in] - Pointer to the connection data.
* authused [in] - The authentication mechanism used.
*/
void Curl_sasl_cleanup(struct connectdata *conn, unsigned int authused)
{
#ifdef USE_NTLM
/* Cleanup the ntlm structure */
if(authused == SASL_MECH_NTLM) {
Curl_ntlm_sspi_cleanup(&conn->ntlm);
}
(void)conn;
#else
/* Reserved for future use */
(void)conn;
(void)authused;
#endif
}
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