/** ssl_rec.c Copyright (C) 1999-2000 RTFM, Inc. All Rights Reserved This package is a SSLv3/TLS protocol analyzer written by Eric Rescorla and licensed by RTFM, Inc. 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. All advertising materials mentioning features or use of this software must display the following acknowledgement: This product includes software developed by Eric Rescorla for RTFM, Inc. 4. Neither the name of RTFM, Inc. nor the name of Eric Rescorla may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY ERIC RESCORLA AND RTFM, INC. ``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 REGENTS 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 SUCH DAMAGE. $Id: ssl_rec.c,v 1.3 2000/11/03 06:38:06 ekr Exp $ ekr@rtfm.com Wed Aug 18 15:46:57 1999 */ static char *RCSSTRING="$Id: ssl_rec.c,v 1.3 2000/11/03 06:38:06 ekr Exp $"; #include "network.h" #include "ssl_h.h" #include "sslprint.h" #include "ssl.enums.h" #ifdef OPENSSL #include #include #include #endif #include "ssldecode.h" #include "ssl_rec.h" struct ssl_rec_decoder_ { SSL_CipherSuite *cs; Data *mac_key; #ifdef OPENSSL EVP_CIPHER_CTX *evp; #endif UINT4 seq; }; static char *digests[]={ "MD5", "SHA1" }; static char *ciphers[]={ "DES", "DES3", "RC4", "RC2", "IDEA", "AES128", "AES256" }; static int tls_check_mac PROTO_LIST((ssl_rec_decoder *d,int ct, int ver,UCHAR *data,UINT4 datalen,UCHAR *mac)); static int fmt_seq PROTO_LIST((UINT4 num,UCHAR *buf)); int ssl_create_rec_decoder(dp,cs,mk,sk,iv) ssl_rec_decoder **dp; SSL_CipherSuite *cs; UCHAR *mk; UCHAR *sk; UCHAR *iv; { int r,_status; ssl_rec_decoder *dec=0; #ifdef OPENSSL const EVP_CIPHER *ciph=0; /* Find the SSLeay cipher */ if(cs->enc!=ENC_NULL){ ciph=(EVP_CIPHER *)EVP_get_cipherbyname(ciphers[cs->enc-0x30]); if(!ciph) ABORT(R_INTERNAL); } else { ciph=EVP_enc_null(); } if(!(dec=(ssl_rec_decoder *)calloc(sizeof(ssl_rec_decoder),1))) ABORT(R_NO_MEMORY); dec->cs=cs; if(r=r_data_create(&dec->mac_key,mk,cs->dig_len)) ABORT(r); if(!(dec->evp=(EVP_CIPHER_CTX *)malloc(sizeof(EVP_CIPHER_CTX)))) ABORT(R_NO_MEMORY); EVP_CIPHER_CTX_init(dec->evp); EVP_CipherInit(dec->evp,ciph,sk,iv,0); #endif *dp=dec; _status=0; abort: if(_status){ ssl_destroy_rec_decoder(&dec); } return(_status); } int ssl_destroy_rec_decoder(dp) ssl_rec_decoder **dp; { ssl_rec_decoder *d; if(!dp || !*dp) return(0); d=*dp; r_data_destroy(&d->mac_key); #ifdef OPENSSL if(d->evp){ EVP_CIPHER_CTX_cleanup(d->evp); free(d->evp); } free(*dp); #endif *dp=0; return(0); } int ssl_decode_rec_data(ssl,d,ct,version,in,inl,out,outl) ssl_obj *ssl; ssl_rec_decoder *d; int ct; int version; UCHAR *in; int inl; UCHAR *out; int *outl; { #ifdef OPENSSL int pad; int r; UCHAR *mac; CRDUMP("Ciphertext",in,inl); /* First decrypt*/ EVP_Cipher(d->evp,out,in,inl); CRDUMP("Plaintext",out,inl); *outl=inl; /* Now strip off the padding*/ if(d->cs->block>1){ pad=out[inl-1]; *outl-=(pad+1); } /* And the MAC */ *outl-=d->cs->dig_len; mac=out+(*outl); CRDUMP("Record data",out,*outl); /* Now check the MAC */ if(ssl->version==0x300){ if(r=ssl3_check_mac(d,ct,version,out,*outl,mac)) ERETURN(r); } else{ if(r=tls_check_mac(d,ct,version,out,*outl,mac)) ERETURN(r); } #endif return(0); } #define MSB(a) ((a>>8)&0xff) #define LSB(a) (a&0xff) #ifdef OPENSSL /* This should go to 2^128, but we're never really going to see more than 2^64, so we cheat*/ static int fmt_seq(num,buf) UINT4 num; UCHAR *buf; { UINT4 netnum; memset(buf,0,8); netnum=htonl(num); memcpy(buf+4,&netnum,4); return(0); } static int tls_check_mac(d,ct,ver,data,datalen,mac) ssl_rec_decoder *d; int ct; int ver; UCHAR *data; UINT4 datalen; UCHAR *mac; { HMAC_CTX hm; const EVP_MD *md; UINT4 l; UCHAR buf[20]; md=EVP_get_digestbyname(digests[d->cs->dig-0x40]); HMAC_Init(&hm,d->mac_key->data,d->mac_key->len,md); fmt_seq(d->seq,buf); d->seq++; HMAC_Update(&hm,buf,8); buf[0]=ct; HMAC_Update(&hm,buf,1); buf[0]=MSB(ver); buf[1]=LSB(ver); HMAC_Update(&hm,buf,2); buf[0]=MSB(datalen); buf[1]=LSB(datalen); HMAC_Update(&hm,buf,2); HMAC_Update(&hm,data,datalen); HMAC_Final(&hm,buf,&l); if(memcmp(mac,buf,l)) ERETURN(SSL_BAD_MAC); HMAC_cleanup(&hm); return(0); } int ssl3_check_mac(d,ct,ver,data,datalen,mac) ssl_rec_decoder *d; int ct; int ver; UCHAR *data; UINT4 datalen; UCHAR *mac; { EVP_MD_CTX mc; const EVP_MD *md; UINT4 l; UCHAR buf[64],dgst[20]; int pad_ct; pad_ct=(d->cs->dig==DIG_SHA)?40:48; md=EVP_get_digestbyname(digests[d->cs->dig-0x40]); EVP_DigestInit(&mc,md); EVP_DigestUpdate(&mc,d->mac_key->data,d->mac_key->len); memset(buf,0x36,pad_ct); EVP_DigestUpdate(&mc,buf,pad_ct); fmt_seq(d->seq,buf); d->seq++; EVP_DigestUpdate(&mc,buf,8); buf[0]=ct; EVP_DigestUpdate(&mc,buf,1); buf[0]=MSB(datalen); buf[1]=LSB(datalen); EVP_DigestUpdate(&mc,buf,2); EVP_DigestUpdate(&mc,data,datalen); EVP_DigestFinal(&mc,dgst,&l); EVP_DigestInit(&mc,md); EVP_DigestUpdate(&mc,d->mac_key->data,d->mac_key->len); memset(buf,0x5c,pad_ct); EVP_DigestUpdate(&mc,buf,pad_ct); EVP_DigestUpdate(&mc,dgst,l); EVP_DigestFinal(&mc,dgst,&l); if(memcmp(mac,dgst,l)) ERETURN(SSL_BAD_MAC); return(0); } #endif