acl/lib_tls/tls/tls_dh.c

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/*++
2014-11-19 00:25:21 +08:00
* NAME
* tls_dh
* SUMMARY
* Diffie-Hellman parameter support
* SYNOPSIS
* #include <tls.h>
* #include <tls_private.h>
*
* void tls_set_dh_from_file(path, bits)
* const char *path;
* int bits;
*
* int tls_set_eecdh_curve(server_ctx, grade)
* SSL_CTX *server_ctx;
* const char *grade;
*
* DH *tls_tmp_dh_cb(ssl, export, keylength)
* SSL *ssl; acl_unused
* int export;
* int keylength;
* DESCRIPTION
* This module maintains parameters for Diffie-Hellman key generation.
*
* tls_tmp_dh_cb() is a call-back routine for the
* SSL_CTX_set_tmp_dh_callback() function.
*
* tls_set_dh_from_file() overrides compiled-in DH parameters
* with those specified in the named files. The file format
* is as expected by the PEM_read_DHparams() routine. The
* "bits" argument must be 512 or 1024.
*
* tls_set_eecdh_curve() enables ephemeral Elliptic-Curve DH
* key exchange algorithms by instantiating in the server SSL
* context a suitable curve (corresponding to the specified
* EECDH security grade) from the set of named curves in RFC
* 4492 Section 5.1.1. Errors generate warnings, but do not
* disable TLS, rather we continue without EECDH. A zero
* result indicates that the grade is invalid or the corresponding
* curve could not be used.
* DIAGNOSTICS
* In case of error, tls_set_dh_from_file() logs a warning and
* ignores the request.
* LICENSE
* .ad
* .fi
* This software is free. You can do with it whatever you want.
* The original author kindly requests that you acknowledge
* the use of his software.
* AUTHOR(S)
* Originally written by:
* Lutz Jaenicke
* BTU Cottbus
* Allgemeine Elektrotechnik
* Universitaetsplatz 3-4
* D-03044 Cottbus, Germany
*
* Updated by:
* Wietse Venema
* IBM T.J. Watson Research
* P.O. Box 704
* Yorktown Heights, NY 10598, USA
*--*/
#include "StdAfx.h"
#ifdef USE_TLS
#include <stdio.h>
/* TLS library. */
#include "tls.h"
#include "tls_params.h"
#include "tls_private.h"
/* Application-specific. */
/*
* Compiled-in EDH primes (the compiled-in generator is always 2). These are
* used when no parameters are explicitly loaded from a site-specific file.
*
* 512-bit parameters are used for export ciphers, and 1024-bit parameters are
* used for non-export ciphers. An ~80-bit strong EDH key exchange is really
* too weak to protect 128+ bit keys, but larger DH primes are
* computationally expensive. When greater security is required, use EECDH.
*/
/*
* Generated via "openssl dhparam -2 -noout -C 512 2>/dev/null" TODO:
* generate at compile-time.
*/
static unsigned char dh512_p[] = {
0x88, 0x3F, 0x00, 0xAF, 0xFC, 0x0C, 0x8A, 0xB8, 0x35, 0xCD, 0xE5, 0xC2,
0x0F, 0x55, 0xDF, 0x06, 0x3F, 0x16, 0x07, 0xBF, 0xCE, 0x13, 0x35, 0xE4,
0x1C, 0x1E, 0x03, 0xF3, 0xAB, 0x17, 0xF6, 0x63, 0x50, 0x63, 0x67, 0x3E,
0x10, 0xD7, 0x3E, 0xB4, 0xEB, 0x46, 0x8C, 0x40, 0x50, 0xE6, 0x91, 0xA5,
0x6E, 0x01, 0x45, 0xDE, 0xC9, 0xB1, 0x1F, 0x64, 0x54, 0xFA, 0xD9, 0xAB,
0x4F, 0x70, 0xBA, 0x5B,
};
/*
* Generated via "openssl dhparam -2 -noout -C 1024 2>/dev/null" TODO:
* generate at compile-time.
*/
static unsigned char dh1024_p[] = {
0xB0, 0xFE, 0xB4, 0xCF, 0xD4, 0x55, 0x07, 0xE7, 0xCC, 0x88, 0x59, 0x0D,
0x17, 0x26, 0xC5, 0x0C, 0xA5, 0x4A, 0x92, 0x23, 0x81, 0x78, 0xDA, 0x88,
0xAA, 0x4C, 0x13, 0x06, 0xBF, 0x5D, 0x2F, 0x9E, 0xBC, 0x96, 0xB8, 0x51,
0x00, 0x9D, 0x0C, 0x0D, 0x75, 0xAD, 0xFD, 0x3B, 0xB1, 0x7E, 0x71, 0x4F,
0x3F, 0x91, 0x54, 0x14, 0x44, 0xB8, 0x30, 0x25, 0x1C, 0xEB, 0xDF, 0x72,
0x9C, 0x4C, 0xF1, 0x89, 0x0D, 0x68, 0x3F, 0x94, 0x8E, 0xA4, 0xFB, 0x76,
0x89, 0x18, 0xB2, 0x91, 0x16, 0x90, 0x01, 0x99, 0x66, 0x8C, 0x53, 0x81,
0x4E, 0x27, 0x3D, 0x99, 0xE7, 0x5A, 0x7A, 0xAF, 0xD5, 0xEC, 0xE2, 0x7E,
0xFA, 0xED, 0x01, 0x18, 0xC2, 0x78, 0x25, 0x59, 0x06, 0x5C, 0x39, 0xF6,
0xCD, 0x49, 0x54, 0xAF, 0xC1, 0xB1, 0xEA, 0x4A, 0xF9, 0x53, 0xD0, 0xDF,
0x6D, 0xAF, 0xD4, 0x93, 0xE7, 0xBA, 0xAE, 0x9B,
};
/*
* Cached results.
*/
static __thread DH *dh_1024 = 0;
static __thread DH *dh_512 = 0;
/* free_dh_cb - call-back for free DH */
static void free_dh_cb(void *arg)
{
DH *dh_tmp = (DH*) arg;
DH_free(dh_tmp);
}
/* tls_set_dh_from_file - set Diffie-Hellman parameters from file */
void tls_set_dh_from_file(const char *path, int bits)
{
const char *myname = "tls_set_dh_from_file";
FILE *paramfile;
DH **dhPtr = 0;
switch (bits) {
case 512:
dhPtr = &dh_512;
break;
case 1024:
dhPtr = &dh_1024;
break;
default:
acl_msg_panic("Invalid DH parameters size %d, file %s", bits, path);
}
if (*dhPtr != 0)
return;
if ((paramfile = fopen(path, "r")) != 0) {
if ((*dhPtr = PEM_read_DHparams(paramfile, 0, 0, 0)) == 0) {
acl_msg_warn("%s: cannot load %d-bit DH parameters from file %s"
" -- using compiled-in defaults", myname, bits, path);
tls_print_errors();
}
(void) fclose(paramfile); /* 200411 */
} else {
acl_msg_warn("%s: cannot load %d-bit DH parameters from file %s: %s"
" -- using compiled-in defaults", myname, bits, path, acl_last_serror());
}
}
/* tls_get_dh - get compiled-in DH parameters */
static DH *tls_get_dh(const unsigned char *p, int plen)
{
const char *myname = "tls_get_dh";
DH *dh;
static unsigned char g[] = {0x02,};
/* Use the compiled-in parameters. */
if ((dh = DH_new()) == 0) {
acl_msg_warn("%s: cannot create DH parameter set: %s",
myname, acl_last_serror()); /* 200411 */
return (0);
}
dh->p = BN_bin2bn(p, plen, (BIGNUM *) 0);
dh->g = BN_bin2bn(g, 1, (BIGNUM *) 0);
if ((dh->p == 0) || (dh->g == 0)) {
acl_msg_warn("%s: cannot load compiled-in DH parameters", myname); /* 200411 */
DH_free(dh); /* 200411 */
return (0);
}
return (dh);
}
/* tls_tmp_dh_cb - call-back for Diffie-Hellman parameters */
DH *tls_tmp_dh_cb(SSL *unused_ssl acl_unused, int export, int keylength)
{
DH *dh_tmp;
if (export && keylength == 512) { /* 40-bit export cipher */
if (dh_512 == 0) {
dh_512 = tls_get_dh(dh512_p, (int) sizeof(dh512_p));
if (dh_512)
acl_pthread_atexit_add(dh_512, free_dh_cb);
}
dh_tmp = dh_512;
} else { /* ADH, DHE-RSA or DSA */
if (dh_1024 == 0) {
dh_1024 = tls_get_dh(dh1024_p, (int) sizeof(dh1024_p));
if (dh_1024)
acl_pthread_atexit_add(dh_1024, free_dh_cb);
}
dh_tmp = dh_1024;
}
return (dh_tmp);
}
int tls_set_eecdh_curve(SSL_CTX *server_ctx acl_unused, const char *grade acl_unused)
{
#if OPENSSL_VERSION_NUMBER >= 0x00909000 && !defined(OPENSSL_NO_ECDH)
const char *myname = "tls_set_eecdh_curve";
int nid;
EC_KEY *ecdh;
const char *curve;
int g;
#define TLS_EECDH_INVALID 0
#define TLS_EECDH_NONE 1
#define TLS_EECDH_STRONG 2
#define TLS_EECDH_ULTRA 3
static NAME_CODE eecdh_table[] = {
"none", TLS_EECDH_NONE,
"strong", TLS_EECDH_STRONG,
"ultra", TLS_EECDH_ULTRA,
0, TLS_EECDH_INVALID,
};
switch (g = name_code(eecdh_table, NAME_CODE_FLAG_NONE, grade)) {
default:
acl_msg_panic("%s: Invalid eecdh grade code: %d", myname, g);
case TLS_EECDH_INVALID:
acl_msg_warn("%s: Invalid TLS eecdh grade \"%s\": EECDH disabled", myname, grade);
return (0);
case TLS_EECDH_NONE:
return (1);
case TLS_EECDH_STRONG:
curve = var_tls_eecdh_strong;
break;
case TLS_EECDH_ULTRA:
curve = var_tls_eecdh_ultra;
break;
}
/*
* Elliptic-Curve Diffie-Hellman parameters are either "named curves"
* from RFC 4492 section 5.1.1, or explicitly described curves over
* binary fields. OpenSSL only supports the "named curves", which provide
* maximum interoperability. The recommended curve for 128-bit
* work-factor key exchange is "prime256v1" a.k.a. "secp256r1" from
* Section 2.7 of http://www.secg.org/download/aid-386/sec2_final.pdf
*/
if ((nid = OBJ_sn2nid(curve)) == NID_undef) {
acl_msg_warn("%s: unknown curve \"%s\": disabling EECDH support", myname, curve);
return (0);
}
ERR_clear_error();
if ((ecdh = EC_KEY_new_by_curve_name(nid)) == 0
|| SSL_CTX_set_tmp_ecdh(server_ctx, ecdh) == 0) {
acl_msg_warn("%s: unable to use curve \"%s\": disabling EECDH support", myname, curve);
tls_print_errors();
return (0);
}
#endif
return (1);
}
#ifdef TEST
int main(int unused_argc, char **unused_argv)
{
tls_tmp_dh_cb(0, 1, 512);
tls_tmp_dh_cb(0, 1, 1024);
tls_tmp_dh_cb(0, 1, 2048);
tls_tmp_dh_cb(0, 0, 512);
return (0);
}
#endif
#endif