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/** |
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* dh.C: DH-BLOWFISH mechanism provider |
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* |
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* Copyright © 2007 Pippijn van Steenhoven / The Ermyth Team |
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* Rights to this code are as documented in COPYING. |
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* |
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* |
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* Portions of this file were derived from sources bearing the following license: |
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* Copyright © 2006 Atheme Development Group |
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* Rights to this code are as documented in doc/pod/license.pod. |
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* |
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* $Id: dh-blowfish.C,v 1.7 2007-09-16 18:54:44 pippijn Exp $ |
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*/ |
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|
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#include "atheme.h" |
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#include <ermyth/module.h> |
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#include <account/myuser.h> |
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#include <sasl.h> |
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|
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#ifdef HAVE_OPENSSL |
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|
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#include <openssl/bn.h> |
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#include <openssl/dh.h> |
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#include <openssl/blowfish.h> |
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#include <arpa/inet.h> |
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|
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static char const rcsid[] = "$Id: dh-blowfish.C,v 1.7 2007-09-16 18:54:44 pippijn Exp $"; |
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|
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REGISTER_MODULE ("saslserv/dh-blowfish", false, "The Ermyth Team <http://ermyth.xinutec.org>"); |
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|
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E list_t sasl_mechanisms; |
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static node_t *mnode; |
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|
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static int mech_start (sasl_session_t *p, char **out, int *out_len); |
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static int mech_step (sasl_session_t *p, char *message, int len, char **out, int *out_len); |
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static void mech_finish (sasl_session_t *p); |
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static sasl_mechanism_t mech ("DH-BLOWFISH", &mech_start, &mech_step, &mech_finish); |
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|
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bool |
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_modinit (module *m) |
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{ |
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mnode = node_create (); |
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node_add (&mech, mnode, &sasl_mechanisms); |
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|
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return true; |
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} |
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|
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void |
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_moddeinit () |
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{ |
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node_del (mnode, &sasl_mechanisms); |
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node_free (mnode); |
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} |
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|
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static int |
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mech_start (sasl_session_t *p, char **out, int *out_len) |
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{ |
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DH *dh; |
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char *ptr; |
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|
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if ((dh = DH_generate_parameters (256, 5, NULL, NULL)) == NULL) |
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return ASASL_FAIL; |
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|
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if (!DH_generate_key (dh)) |
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{ |
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DH_free (dh); |
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return ASASL_FAIL; |
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} |
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|
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/* Serialize p, g, and pub_key */ |
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*out = salloc<char> (BN_num_bytes (dh->p) + BN_num_bytes (dh->g) + BN_num_bytes (dh->pub_key) + 6); |
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*out_len = BN_num_bytes (dh->p) + BN_num_bytes (dh->g) + BN_num_bytes (dh->pub_key) + 6; |
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ptr = *out; |
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|
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/* p */ |
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*((unsigned int *) ptr) = htons (BN_num_bytes (dh->p)); |
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BN_bn2bin (dh->p, (unsigned char *) ptr + 2); |
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ptr += 2 + BN_num_bytes (dh->p); |
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|
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/* g */ |
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*((unsigned int *) ptr) = htons (BN_num_bytes (dh->g)); |
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BN_bn2bin (dh->g, (unsigned char *) ptr + 2); |
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ptr += 2 + BN_num_bytes (dh->g); |
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|
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/* pub_key */ |
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*((unsigned int *) ptr) = htons (BN_num_bytes (dh->pub_key)); |
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BN_bn2bin (dh->pub_key, (unsigned char *) ptr + 2); |
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ptr += 2 + BN_num_bytes (dh->pub_key); |
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|
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p->mechdata = dh; |
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return ASASL_MORE; |
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} |
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|
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static int |
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mech_step (sasl_session_t *p, char *message, int len, char **out, int *out_len) |
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{ |
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DH *dh = NULL; |
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BF_KEY key; |
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BIGNUM *their_key = NULL; |
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myuser_t *mu; |
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char *ptr, *secret = NULL, *password = NULL; |
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int size, ret = ASASL_FAIL; |
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|
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if (!p->mechdata) |
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return ASASL_FAIL; |
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dh = (DH *) p->mechdata; |
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|
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/* Their pub_key */ |
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if (len < 2) |
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goto end; |
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size = ntohs (*(unsigned int *) message); |
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message += 2; |
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len -= 2; |
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if (size > len) |
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goto end; |
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if ((their_key = BN_bin2bn ((unsigned char *) message, size, NULL)) == NULL) |
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goto end; |
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message += size; |
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len -= size; |
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|
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/* Username */ |
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size = strlen (message); |
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if (size >= NICKLEN) /* our base64 routines null-terminate - how polite */ |
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goto end; |
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p->username = strdup (message); |
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message += size + 1; |
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len -= size + 1; |
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if ((mu = myuser_t::find (p->username)) == NULL) |
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goto end; |
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/* AES-encrypted password remains */ |
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|
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/* Compute shared secret */ |
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secret = salloc<char> (DH_size (dh)); |
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if ((size = DH_compute_key ((unsigned char *) secret, their_key, dh)) == -1) |
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goto end; |
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|
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/* Data must be multiple of block size, and let's be reasonable about size */ |
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if (len == 0 || len % 8 || len > 128) |
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goto end; |
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|
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/* Decrypt! */ |
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BF_set_key (&key, size, (unsigned char *) secret); |
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ptr = password = salloc<char> (len + 1); |
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password[len] = '\0'; |
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while (len) |
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{ |
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BF_ecb_encrypt ((unsigned char *) message, (unsigned char *) ptr, &key, BF_DECRYPT); |
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message += 8; |
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ptr += 8; |
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len -= 8; |
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} |
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|
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if (mu->verify_password (password)) |
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ret = ASASL_DONE; |
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|
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end: |
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if (their_key) |
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BN_free (their_key); |
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sfree (secret); |
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sfree (password); |
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return ret; |
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} |
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|
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static void |
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mech_finish (sasl_session_t *p) |
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{ |
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if (p && p->mechdata) |
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{ |
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DH_free ((DH *) p->mechdata); |
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p->mechdata = NULL; |
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} |
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} |
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|
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#endif /* HAVE_OPENSSL */ |
