int mm_answer_gss_checkmic(int sock, Buffer *m) { gss_buffer_desc gssbuf, mic; OM_uint32 ret; u_int len; gssbuf.value = buffer_get_string(m, &len); gssbuf.length = len; mic.value = buffer_get_string(m, &len); mic.length = len; ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic); xfree(gssbuf.value); xfree(mic.value); buffer_clear(m); buffer_put_int(m, ret); mm_request_send(sock, MONITOR_ANS_GSSCHECKMIC, m); if (!GSS_ERROR(ret)) monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); return (0); }
/* * The 'gssapi_keyex' userauth mechanism. */ static int userauth_gsskeyex(Authctxt *authctxt) { int authenticated = 0; Buffer b; gss_buffer_desc mic, gssbuf; u_int len; mic.value = packet_get_string(&len); mic.length = len; packet_check_eom(); ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service, "gssapi-keyex"); gssbuf.value = buffer_ptr(&b); gssbuf.length = buffer_len(&b); gssapi_set_username(authctxt); /* gss_kex_context is NULL with privsep, so we can't check it here */ if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gss_kex_context, &gssbuf, &mic)))) authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user, authctxt->pw)); buffer_free(&b); xfree(mic.value); return (authenticated); }
int mm_answer_gss_checkmic(int sock, struct sshbuf *m) { gss_buffer_desc gssbuf, mic; OM_uint32 ret; size_t len; int r; u_char *p; if ((r = sshbuf_get_string(m, &p, &len)) != 0) fatal("%s: buffer error: %s", __func__, ssh_err(r)); gssbuf.value = p; gssbuf.length = len; if ((r = sshbuf_get_string(m, &p, &len)) != 0) fatal("%s: buffer error: %s", __func__, ssh_err(r)); mic.value = p; mic.length = len; ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic); free(gssbuf.value); free(mic.value); sshbuf_reset(m); if ((r = sshbuf_put_u32(m, ret)) != 0) fatal("%s: buffer error: %s", __func__, ssh_err(r)); mm_request_send(sock, MONITOR_ANS_GSSCHECKMIC, m); if (!GSS_ERROR(ret)) monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); return 0; }
static int input_gssapi_mic(int type, u_int32_t plen, struct ssh *ssh) { Authctxt *authctxt = ssh->authctxt; Gssctxt *gssctxt; int r, authenticated = 0; struct sshbuf *b; gss_buffer_desc mic, gssbuf; const char *displayname; u_char *p; size_t len; if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) fatal("No authentication or GSSAPI context"); gssctxt = authctxt->methoddata; if ((r = sshpkt_get_string(ssh, &p, &len)) != 0) fatal("%s: %s", __func__, ssh_err(r)); if ((b = sshbuf_new()) == NULL) fatal("%s: sshbuf_new failed", __func__); mic.value = p; mic.length = len; ssh_gssapi_buildmic(b, authctxt->user, authctxt->service, "gssapi-with-mic"); if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) fatal("%s: sshbuf_mutable_ptr failed", __func__); gssbuf.length = sshbuf_len(b); if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic)))) authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); else logit("GSSAPI MIC check failed"); sshbuf_free(b); free(mic.value); if ((!use_privsep || mm_is_monitor()) && (displayname = ssh_gssapi_displayname()) != NULL) auth2_record_info(authctxt, "%s", displayname); authctxt->postponed = 0; ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL); ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); userauth_finish(ssh, authenticated, "gssapi-with-mic", NULL); return 0; }
static int input_gssapi_mic(int type, u_int32_t plen, void *ctxt) { Authctxt *authctxt = ctxt; Gssctxt *gssctxt; int authenticated = 0; Buffer b; gss_buffer_desc mic, gssbuf; u_int len; if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) fatal("No authentication or GSSAPI context"); gssctxt = authctxt->methoddata; mic.value = packet_get_string(&len); mic.length = len; ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service, "gssapi-with-mic"); gssbuf.value = buffer_ptr(&b); gssbuf.length = buffer_len(&b); if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic)))) authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); else logit("GSSAPI MIC check failed"); if (authenticated) authctxt->last_details = ssh_gssapi_get_displayname(); buffer_free(&b); free(mic.value); authctxt->postponed = 0; dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL); dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); userauth_finish(authctxt, authenticated, "gssapi-with-mic", NULL); return 0; }
void kexgss_client(Kex *kex) { gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; gss_buffer_desc recv_tok, gssbuf, msg_tok, *token_ptr; Gssctxt *ctxt; OM_uint32 maj_status, min_status, ret_flags; u_int klen, kout, slen = 0, hashlen, strlen; DH *dh; BIGNUM *dh_server_pub = NULL; BIGNUM *shared_secret = NULL; BIGNUM *p = NULL; BIGNUM *g = NULL; u_char *kbuf, *hash; u_char *serverhostkey = NULL; u_char *empty = ""; char *msg; char *lang; int type = 0; int first = 1; int nbits = 0, min = DH_GRP_MIN, max = DH_GRP_MAX; /* Initialise our GSSAPI world */ ssh_gssapi_build_ctx(&ctxt); if (ssh_gssapi_id_kex(ctxt, kex->name, kex->kex_type) == GSS_C_NO_OID) fatal("Couldn't identify host exchange"); if (ssh_gssapi_import_name(ctxt, kex->gss_host)) fatal("Couldn't import hostname"); if (kex->gss_client && ssh_gssapi_client_identity(ctxt, kex->gss_client)) fatal("Couldn't acquire client credentials"); switch (kex->kex_type) { case KEX_GSS_GRP1_SHA1: dh = dh_new_group1(); break; case KEX_GSS_GRP14_SHA1: dh = dh_new_group14(); break; case KEX_GSS_GEX_SHA1: debug("Doing group exchange\n"); nbits = dh_estimate(kex->we_need * 8); packet_start(SSH2_MSG_KEXGSS_GROUPREQ); packet_put_int(min); packet_put_int(nbits); packet_put_int(max); packet_send(); packet_read_expect(SSH2_MSG_KEXGSS_GROUP); if ((p = BN_new()) == NULL) fatal("BN_new() failed"); packet_get_bignum2(p); if ((g = BN_new()) == NULL) fatal("BN_new() failed"); packet_get_bignum2(g); packet_check_eom(); if (BN_num_bits(p) < min || BN_num_bits(p) > max) fatal("GSSGRP_GEX group out of range: %d !< %d !< %d", min, BN_num_bits(p), max); dh = dh_new_group(g, p); break; default: fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type); } /* Step 1 - e is dh->pub_key */ dh_gen_key(dh, kex->we_need * 8); /* This is f, we initialise it now to make life easier */ dh_server_pub = BN_new(); if (dh_server_pub == NULL) fatal("dh_server_pub == NULL"); token_ptr = GSS_C_NO_BUFFER; do { debug("Calling gss_init_sec_context"); maj_status = ssh_gssapi_init_ctx(ctxt, kex->gss_deleg_creds, token_ptr, &send_tok, &ret_flags); if (GSS_ERROR(maj_status)) { if (send_tok.length != 0) { packet_start(SSH2_MSG_KEXGSS_CONTINUE); packet_put_string(send_tok.value, send_tok.length); } fatal("gss_init_context failed"); } /* If we've got an old receive buffer get rid of it */ if (token_ptr != GSS_C_NO_BUFFER) xfree(recv_tok.value); if (maj_status == GSS_S_COMPLETE) { /* If mutual state flag is not true, kex fails */ if (!(ret_flags & GSS_C_MUTUAL_FLAG)) fatal("Mutual authentication failed"); /* If integ avail flag is not true kex fails */ if (!(ret_flags & GSS_C_INTEG_FLAG)) fatal("Integrity check failed"); } /* * If we have data to send, then the last message that we * received cannot have been a 'complete'. */ if (send_tok.length != 0) { if (first) { packet_start(SSH2_MSG_KEXGSS_INIT); packet_put_string(send_tok.value, send_tok.length); packet_put_bignum2(dh->pub_key); first = 0; } else { packet_start(SSH2_MSG_KEXGSS_CONTINUE); packet_put_string(send_tok.value, send_tok.length); } packet_send(); gss_release_buffer(&min_status, &send_tok); /* If we've sent them data, they should reply */ do { type = packet_read(); if (type == SSH2_MSG_KEXGSS_HOSTKEY) { debug("Received KEXGSS_HOSTKEY"); if (serverhostkey) fatal("Server host key received more than once"); serverhostkey = packet_get_string(&slen); } } while (type == SSH2_MSG_KEXGSS_HOSTKEY); switch (type) { case SSH2_MSG_KEXGSS_CONTINUE: debug("Received GSSAPI_CONTINUE"); if (maj_status == GSS_S_COMPLETE) fatal("GSSAPI Continue received from server when complete"); recv_tok.value = packet_get_string(&strlen); recv_tok.length = strlen; break; case SSH2_MSG_KEXGSS_COMPLETE: debug("Received GSSAPI_COMPLETE"); packet_get_bignum2(dh_server_pub); msg_tok.value = packet_get_string(&strlen); msg_tok.length = strlen; /* Is there a token included? */ if (packet_get_char()) { recv_tok.value= packet_get_string(&strlen); recv_tok.length = strlen; /* If we're already complete - protocol error */ if (maj_status == GSS_S_COMPLETE) packet_disconnect("Protocol error: received token when complete"); } else { /* No token included */ if (maj_status != GSS_S_COMPLETE) packet_disconnect("Protocol error: did not receive final token"); } break; case SSH2_MSG_KEXGSS_ERROR: debug("Received Error"); maj_status = packet_get_int(); min_status = packet_get_int(); msg = packet_get_string(NULL); lang = packet_get_string(NULL); fatal("GSSAPI Error: \n%.400s",msg); default: packet_disconnect("Protocol error: didn't expect packet type %d", type); } token_ptr = &recv_tok; } else { /* No data, and not complete */ if (maj_status != GSS_S_COMPLETE) fatal("Not complete, and no token output"); } } while (maj_status & GSS_S_CONTINUE_NEEDED); /* * We _must_ have received a COMPLETE message in reply from the * server, which will have set dh_server_pub and msg_tok */ if (type != SSH2_MSG_KEXGSS_COMPLETE) fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it"); /* Check f in range [1, p-1] */ if (!dh_pub_is_valid(dh, dh_server_pub)) packet_disconnect("bad server public DH value"); /* compute K=f^x mod p */ klen = DH_size(dh); kbuf = xmalloc(klen); kout = DH_compute_key(kbuf, dh_server_pub, dh); if (kout < 0) fatal("DH_compute_key: failed"); shared_secret = BN_new(); if (shared_secret == NULL) fatal("kexgss_client: BN_new failed"); if (BN_bin2bn(kbuf, kout, shared_secret) == NULL) fatal("kexdh_client: BN_bin2bn failed"); memset(kbuf, 0, klen); xfree(kbuf); switch (kex->kex_type) { case KEX_GSS_GRP1_SHA1: case KEX_GSS_GRP14_SHA1: kex_dh_hash( kex->client_version_string, kex->server_version_string, buffer_ptr(&kex->my), buffer_len(&kex->my), buffer_ptr(&kex->peer), buffer_len(&kex->peer), (serverhostkey ? serverhostkey : empty), slen, dh->pub_key, /* e */ dh_server_pub, /* f */ shared_secret, /* K */ &hash, &hashlen ); break; case KEX_GSS_GEX_SHA1: kexgex_hash( kex->evp_md, kex->client_version_string, kex->server_version_string, buffer_ptr(&kex->my), buffer_len(&kex->my), buffer_ptr(&kex->peer), buffer_len(&kex->peer), (serverhostkey ? serverhostkey : empty), slen, min, nbits, max, dh->p, dh->g, dh->pub_key, dh_server_pub, shared_secret, &hash, &hashlen ); break; default: fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type); } gssbuf.value = hash; gssbuf.length = hashlen; /* Verify that the hash matches the MIC we just got. */ if (GSS_ERROR(ssh_gssapi_checkmic(ctxt, &gssbuf, &msg_tok))) packet_disconnect("Hash's MIC didn't verify"); xfree(msg_tok.value); DH_free(dh); if (serverhostkey) xfree(serverhostkey); BN_clear_free(dh_server_pub); /* save session id */ if (kex->session_id == NULL) { kex->session_id_len = hashlen; kex->session_id = xmalloc(kex->session_id_len); memcpy(kex->session_id, hash, kex->session_id_len); } if (kex->gss_deleg_creds) ssh_gssapi_credentials_updated(ctxt); if (gss_kex_context == NULL) gss_kex_context = ctxt; else ssh_gssapi_delete_ctx(&ctxt); kex_derive_keys(kex, hash, hashlen, shared_secret); BN_clear_free(shared_secret); kex_finish(kex); }