Improve SSHv1 key exchange functions.
git-svn-id: svn+ssh://svn.berlios.de/svnroot/repos/libssh/trunk@426 7dcaeef0-15fb-0310-b436-a5af3365683c
Этот коммит содержится в:
Andreas Schneider
родитель
faa83b2380
Коммит
4f6fd0c451
410
libssh/kex.c
410
libssh/kex.c
@ -472,28 +472,28 @@ error:
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return ret;
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}
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/* TODO FIXME add return value and error checking in callers */
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static void build_session_id1(SSH_SESSION *session, STRING *servern,
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STRING *hostn){
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MD5CTX md5;
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md5 = md5_init();
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if (md5 == NULL) {
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return;
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}
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static int build_session_id1(SSH_SESSION *session, STRING *servern,
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STRING *hostn) {
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MD5CTX md5 = NULL;
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md5 = md5_init();
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if (md5 == NULL) {
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return -1;
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}
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#ifdef DEBUG_CRYPTO
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ssh_print_hexa("host modulus",hostn->string,string_len(hostn));
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ssh_print_hexa("server modulus",servern->string,string_len(servern));
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ssh_print_hexa("host modulus",hostn->string,string_len(hostn));
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ssh_print_hexa("server modulus",servern->string,string_len(servern));
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#endif
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md5_update(md5,hostn->string,string_len(hostn));
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md5_update(md5,servern->string,string_len(servern));
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md5_update(md5,session->server_kex.cookie,8);
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md5_final(session->next_crypto->session_id,md5);
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md5_update(md5,hostn->string,string_len(hostn));
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md5_update(md5,servern->string,string_len(servern));
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md5_update(md5,session->server_kex.cookie,8);
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md5_final(session->next_crypto->session_id,md5);
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#ifdef DEBUG_CRYPTO
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ssh_print_hexa("session_id",session->next_crypto->session_id,MD5_DIGEST_LEN);
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ssh_print_hexa("session_id",session->next_crypto->session_id,MD5_DIGEST_LEN);
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#endif
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return 0;
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}
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/* returns 1 if the modulus of k1 is < than the one of k2 */
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@ -526,41 +526,65 @@ static int modulus_smaller(PUBLIC_KEY *k1, PUBLIC_KEY *k2){
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}
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#define ABS(A) ( (A)<0 ? -(A):(A) )
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static STRING *encrypt_session_key(SSH_SESSION *session, PUBLIC_KEY *svrkey,
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PUBLIC_KEY *hostkey,int slen, int hlen ){
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unsigned char buffer[32];
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int i;
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STRING *data1,*data2;
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/* first, generate a session key */
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ssh_get_random(session->next_crypto->encryptkey,32,1);
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memcpy(buffer,session->next_crypto->encryptkey,32);
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memcpy(session->next_crypto->decryptkey,
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session->next_crypto->encryptkey,32);
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static STRING *encrypt_session_key(SSH_SESSION *session, PUBLIC_KEY *srvkey,
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PUBLIC_KEY *hostkey, int slen, int hlen) {
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unsigned char buffer[32] = {0};
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int i;
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STRING *data1 = NULL;
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STRING *data2 = NULL;
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/* first, generate a session key */
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ssh_get_random(session->next_crypto->encryptkey, 32, 1);
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memcpy(buffer, session->next_crypto->encryptkey, 32);
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memcpy(session->next_crypto->decryptkey, session->next_crypto->encryptkey, 32);
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#ifdef DEBUG_CRYPTO
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ssh_print_hexa("session key",buffer,32);
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ssh_print_hexa("session key",buffer,32);
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#endif
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/* xor session key with session_id */
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for (i=0;i<16;++i)
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buffer[i]^=session->next_crypto->session_id[i];
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data1=string_new(32);
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string_fill(data1,buffer,32);
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if(ABS(hlen-slen)<128){
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ssh_log(session, SSH_LOG_FUNCTIONS,
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"Difference between server modulus and host modulus is only %d. "
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"It's illegal and may not work",
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ABS(hlen-slen));
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/* xor session key with session_id */
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for (i = 0; i < 16; i++) {
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buffer[i] ^= session->next_crypto->session_id[i];
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}
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data1 = string_new(32);
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if (data1 == NULL) {
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return NULL;
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}
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string_fill(data1, buffer, 32);
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if (ABS(hlen - slen) < 128){
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ssh_log(session, SSH_LOG_FUNCTIONS,
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"Difference between server modulus and host modulus is only %d. "
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"It's illegal and may not work",
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ABS(hlen - slen));
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}
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if (modulus_smaller(srvkey, hostkey)) {
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data2 = ssh_encrypt_rsa1(session, data1, srvkey);
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string_free(data1);
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data1 = NULL;
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if (data2 == NULL) {
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return NULL;
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}
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if(modulus_smaller(svrkey,hostkey)){
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data2=ssh_encrypt_rsa1(session,data1,svrkey);
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free(data1);
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data1=ssh_encrypt_rsa1(session,data2,hostkey);
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} else {
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data2=ssh_encrypt_rsa1(session,data1,hostkey);
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free(data1);
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data1=ssh_encrypt_rsa1(session,data2,svrkey);
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data1 = ssh_encrypt_rsa1(session, data2, hostkey);
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string_free(data2);
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if (data1 == NULL) {
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return NULL;
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}
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return data1;
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} else {
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data2 = ssh_encrypt_rsa1(session, data1, hostkey);
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string_free(data1);
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data1 = NULL;
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if (data2 == NULL) {
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return NULL;
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}
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data1 = ssh_encrypt_rsa1(session, data2, srvkey);
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string_free(data2);
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if (data1 == NULL) {
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return NULL;
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}
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}
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return data1;
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}
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@ -579,120 +603,184 @@ static STRING *encrypt_session_key(SSH_SESSION *session, PUBLIC_KEY *svrkey,
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* 32-bit int supported_authentications_mask
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*/
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int ssh_get_kex1(SSH_SESSION *session){
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u32 server_bits, host_bits, protocol_flags,
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supported_ciphers_mask, supported_authentications_mask;
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STRING *server_exp=NULL;
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STRING *server_mod=NULL;
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STRING *host_exp=NULL;
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STRING *host_mod=NULL;
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STRING *serverkey;
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STRING *hostkey;
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STRING *enc_session;
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PUBLIC_KEY *svr,*host;
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int ko;
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u16 bits;
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enter_function();
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ssh_log(session,SSH_LOG_PROTOCOL,"Waiting for a SSH_SMSG_PUBLIC_KEY");
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if(packet_wait(session,SSH_SMSG_PUBLIC_KEY,1)){
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leave_function();
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return -1;
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}
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ssh_log(session,SSH_LOG_PROTOCOL,"Got a SSH_SMSG_PUBLIC_KEY");
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if(buffer_get_data(session->in_buffer,session->server_kex.cookie,8)!=8){
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ssh_set_error(session,SSH_FATAL,"Can't get cookie in buffer");
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leave_function();
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return -1;
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}
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buffer_get_u32(session->in_buffer,&server_bits);
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server_exp=buffer_get_mpint(session->in_buffer);
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server_mod=buffer_get_mpint(session->in_buffer);
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buffer_get_u32(session->in_buffer,&host_bits);
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host_exp=buffer_get_mpint(session->in_buffer);
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host_mod=buffer_get_mpint(session->in_buffer);
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buffer_get_u32(session->in_buffer,&protocol_flags);
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buffer_get_u32(session->in_buffer,&supported_ciphers_mask);
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ko=buffer_get_u32(session->in_buffer,&supported_authentications_mask);
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if((ko!=sizeof(u32)) || !host_mod || !host_exp || !server_mod || !server_exp){
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ssh_log(session,SSH_LOG_RARE,"Invalid SSH_SMSG_PUBLIC_KEY packet");
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ssh_set_error(session,SSH_FATAL,"Invalid SSH_SMSG_PUBLIC_KEY packet");
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if(host_mod)
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free(host_mod);
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if(host_exp)
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free(host_exp);
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if(server_mod)
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free(server_mod);
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if(server_exp)
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free(server_exp);
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leave_function();
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return -1;
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}
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server_bits=ntohl(server_bits);
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host_bits=ntohl(host_bits);
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protocol_flags=ntohl(protocol_flags);
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supported_ciphers_mask=ntohl(supported_ciphers_mask);
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supported_authentications_mask=ntohl(supported_authentications_mask);
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ssh_log(session,SSH_LOG_PROTOCOL,"server bits: %d ; host bits: %d Protocol flags : %.8lx ; "
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"cipher mask : %.8lx ; auth mask: %.8lx",
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server_bits,
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host_bits,
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(unsigned long int) protocol_flags,
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(unsigned long int) supported_ciphers_mask,
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(unsigned long int) supported_authentications_mask);
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serverkey=make_rsa1_string(server_exp,server_mod);
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hostkey=make_rsa1_string(host_exp,host_mod);
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build_session_id1(session,server_mod,host_mod);
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free(server_exp);
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free(server_mod);
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free(host_exp);
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free(host_mod);
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svr=publickey_from_string(session, serverkey);
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host=publickey_from_string(session, hostkey);
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session->next_crypto->server_pubkey=string_copy(hostkey);
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session->next_crypto->server_pubkey_type="ssh-rsa1";
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int ssh_get_kex1(SSH_SESSION *session) {
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STRING *server_exp = NULL;
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STRING *server_mod = NULL;
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STRING *host_exp = NULL;
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STRING *host_mod = NULL;
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STRING *serverkey = NULL;
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STRING *hostkey = NULL;
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STRING *enc_session = NULL;
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PUBLIC_KEY *srv = NULL;
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PUBLIC_KEY *host = NULL;
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u32 server_bits;
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u32 host_bits;
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u32 protocol_flags;
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u32 supported_ciphers_mask;
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u32 supported_authentications_mask;
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u16 bits;
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int rc = -1;
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int ko;
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/* now, we must choose an encryption algo */
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/* hardcode 3des */
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if(!(supported_ciphers_mask & (1<<SSH_CIPHER_3DES))){
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ssh_set_error(session,SSH_FATAL,"Remote server doesn't accept 3des");
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leave_function();
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return -1;
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}
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ssh_log(session,SSH_LOG_PROTOCOL,"sending SSH_CMSG_SESSION_KEY");
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buffer_add_u8(session->out_buffer,SSH_CMSG_SESSION_KEY);
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buffer_add_u8(session->out_buffer,SSH_CIPHER_3DES);
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buffer_add_data(session->out_buffer,session->server_kex.cookie,8);
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enc_session=encrypt_session_key(session,svr,host,server_bits, host_bits);
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bits=string_len(enc_session)*8 - 7;
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ssh_log(session, SSH_LOG_PROTOCOL, "%d bits, %zu bytes encrypted session",
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bits, string_len(enc_session));
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bits=htons(bits);
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/* the encrypted mpint */
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buffer_add_data(session->out_buffer,&bits,sizeof(u16));
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buffer_add_data(session->out_buffer,enc_session->string,
|
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string_len(enc_session));
|
||||
/* the protocol flags */
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||||
buffer_add_u32(session->out_buffer,0);
|
||||
|
||||
packet_send(session);
|
||||
/* we can set encryption */
|
||||
if(crypt_set_algorithms(session)){
|
||||
leave_function();
|
||||
return -1;
|
||||
}
|
||||
session->current_crypto=session->next_crypto;
|
||||
session->next_crypto=NULL;
|
||||
ssh_log(session,SSH_LOG_PROTOCOL,"Waiting for a SSH_SMSG_SUCCESS");
|
||||
if(packet_wait(session,SSH_SMSG_SUCCESS,1)){
|
||||
char buffer[1024];
|
||||
snprintf(buffer,sizeof(buffer),"Key exchange failed : %s",ssh_get_error(session));
|
||||
ssh_set_error(session,SSH_FATAL,"%s",buffer);
|
||||
leave_function();
|
||||
return -1;
|
||||
}
|
||||
ssh_log(session,SSH_LOG_PROTOCOL,"received SSH_SMSG_SUCCESS\n");
|
||||
enter_function();
|
||||
ssh_log(session, SSH_LOG_PROTOCOL, "Waiting for a SSH_SMSG_PUBLIC_KEY");
|
||||
if (packet_wait(session, SSH_SMSG_PUBLIC_KEY, 1)) {
|
||||
leave_function();
|
||||
return 0;
|
||||
|
||||
return -1;
|
||||
}
|
||||
|
||||
ssh_log(session, SSH_LOG_PROTOCOL, "Got a SSH_SMSG_PUBLIC_KEY");
|
||||
if (buffer_get_data(session->in_buffer, session->server_kex.cookie, 8) != 8) {
|
||||
ssh_set_error(session, SSH_FATAL, "Can't get cookie in buffer");
|
||||
leave_function();
|
||||
return -1;
|
||||
}
|
||||
|
||||
buffer_get_u32(session->in_buffer, &server_bits);
|
||||
server_exp = buffer_get_mpint(session->in_buffer);
|
||||
if (server_exp == NULL) {
|
||||
goto error;
|
||||
}
|
||||
server_mod = buffer_get_mpint(session->in_buffer);
|
||||
if (server_mod == NULL) {
|
||||
goto error;
|
||||
}
|
||||
buffer_get_u32(session->in_buffer, &host_bits);
|
||||
host_exp = buffer_get_mpint(session->in_buffer);
|
||||
if (host_exp == NULL) {
|
||||
goto error;
|
||||
}
|
||||
host_mod = buffer_get_mpint(session->in_buffer);
|
||||
if (host_mod == NULL) {
|
||||
goto error;
|
||||
}
|
||||
buffer_get_u32(session->in_buffer, &protocol_flags);
|
||||
buffer_get_u32(session->in_buffer, &supported_ciphers_mask);
|
||||
ko = buffer_get_u32(session->in_buffer, &supported_authentications_mask);
|
||||
|
||||
if ((ko != sizeof(u32)) || !host_mod || !host_exp
|
||||
|| !server_mod || !server_exp) {
|
||||
ssh_log(session, SSH_LOG_RARE, "Invalid SSH_SMSG_PUBLIC_KEY packet");
|
||||
ssh_set_error(session, SSH_FATAL, "Invalid SSH_SMSG_PUBLIC_KEY packet");
|
||||
goto error;
|
||||
}
|
||||
|
||||
server_bits = ntohl(server_bits);
|
||||
host_bits = ntohl(host_bits);
|
||||
protocol_flags = ntohl(protocol_flags);
|
||||
supported_ciphers_mask = ntohl(supported_ciphers_mask);
|
||||
supported_authentications_mask = ntohl(supported_authentications_mask);
|
||||
ssh_log(session, SSH_LOG_PROTOCOL,
|
||||
"Server bits: %d; Host bits: %d; Protocol flags: %.8lx; "
|
||||
"Cipher mask: %.8lx; Auth mask: %.8lx",
|
||||
server_bits,
|
||||
host_bits,
|
||||
(unsigned long int) protocol_flags,
|
||||
(unsigned long int) supported_ciphers_mask,
|
||||
(unsigned long int) supported_authentications_mask);
|
||||
|
||||
serverkey = make_rsa1_string(server_exp, server_mod);
|
||||
if (serverkey == NULL) {
|
||||
goto error;
|
||||
}
|
||||
hostkey = make_rsa1_string(host_exp,host_mod);
|
||||
if (serverkey == NULL) {
|
||||
goto error;
|
||||
}
|
||||
if (build_session_id1(session, server_mod, host_mod) < 0) {
|
||||
goto error;
|
||||
}
|
||||
|
||||
srv = publickey_from_string(session, serverkey);
|
||||
if (srv == NULL) {
|
||||
goto error;
|
||||
}
|
||||
host = publickey_from_string(session, hostkey);
|
||||
if (host == NULL) {
|
||||
goto error;
|
||||
}
|
||||
|
||||
session->next_crypto->server_pubkey = string_copy(hostkey);
|
||||
if (session->next_crypto->server_pubkey == NULL) {
|
||||
goto error;
|
||||
}
|
||||
session->next_crypto->server_pubkey_type = "ssh-rsa1";
|
||||
|
||||
/* now, we must choose an encryption algo */
|
||||
/* hardcode 3des */
|
||||
if (!(supported_ciphers_mask & (1 << SSH_CIPHER_3DES))) {
|
||||
ssh_set_error(session, SSH_FATAL, "Remote server doesn't accept 3DES");
|
||||
goto error;
|
||||
}
|
||||
|
||||
ssh_log(session, SSH_LOG_PROTOCOL, "Sending SSH_CMSG_SESSION_KEY");
|
||||
|
||||
if (buffer_add_u8(session->out_buffer, SSH_CMSG_SESSION_KEY) < 0) {
|
||||
goto error;
|
||||
}
|
||||
if (buffer_add_u8(session->out_buffer, SSH_CIPHER_3DES) < 0) {
|
||||
goto error;
|
||||
}
|
||||
if (buffer_add_data(session->out_buffer, session->server_kex.cookie, 8) < 0) {
|
||||
goto error;
|
||||
}
|
||||
|
||||
enc_session = encrypt_session_key(session, srv, host, server_bits, host_bits);
|
||||
if (enc_session == NULL) {
|
||||
goto error;
|
||||
}
|
||||
|
||||
bits = string_len(enc_session) * 8 - 7;
|
||||
ssh_log(session, SSH_LOG_PROTOCOL, "%d bits, %zu bytes encrypted session",
|
||||
bits, string_len(enc_session));
|
||||
bits = htons(bits);
|
||||
/* the encrypted mpint */
|
||||
if (buffer_add_data(session->out_buffer, &bits, sizeof(u16)) < 0) {
|
||||
goto error;
|
||||
}
|
||||
if (buffer_add_data(session->out_buffer, enc_session->string,
|
||||
string_len(enc_session)) < 0) {
|
||||
goto error;
|
||||
}
|
||||
/* the protocol flags */
|
||||
if (buffer_add_u32(session->out_buffer, 0) < 0) {
|
||||
goto error;
|
||||
}
|
||||
|
||||
if (packet_send(session) != SSH_OK) {
|
||||
goto error;
|
||||
}
|
||||
|
||||
/* we can set encryption */
|
||||
if (crypt_set_algorithms(session)) {
|
||||
goto error;
|
||||
}
|
||||
|
||||
session->current_crypto = session->next_crypto;
|
||||
session->next_crypto = NULL;
|
||||
|
||||
ssh_log(session, SSH_LOG_PROTOCOL, "Waiting for a SSH_SMSG_SUCCESS");
|
||||
if (packet_wait(session,SSH_SMSG_SUCCESS,1)) {
|
||||
char buffer[1024] = {0};
|
||||
snprintf(buffer, sizeof(buffer),
|
||||
"Key exchange failed: %s", ssh_get_error(session));
|
||||
ssh_set_error(session, SSH_FATAL, "%s",buffer);
|
||||
goto error;
|
||||
}
|
||||
ssh_log(session, SSH_LOG_PROTOCOL, "received SSH_SMSG_SUCCESS\n");
|
||||
|
||||
rc = 0;
|
||||
error:
|
||||
string_free(host_mod);
|
||||
string_free(host_exp);
|
||||
string_free(server_mod);
|
||||
string_free(server_exp);
|
||||
string_free(serverkey);
|
||||
string_free(hostkey);
|
||||
|
||||
publickey_free(srv);
|
||||
publickey_free(host);
|
||||
|
||||
leave_function();
|
||||
return -1;
|
||||
}
|
||||
|
||||
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Ссылка в новой задаче
Block a user