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https://git.tartarus.org/simon/putty.git
synced 2025-01-09 17:38:00 +00:00
Reworking of packet delivery to coroutines in SSH-2.
Before, NULL in the dispatch table meant "send to the appropriate one of do_ssh2_transport() and do_ssh2_authconn()". Now those (via small shims) are specified directly in the dispatch table, so ssh2_protocol() is much simpler. In the process, this has somewhat centralised the handling of gross server protocol violations. PuTTY will now disconnect with a rude message when (e.g.) OpenSSH sends us an SSH_MSG_UNIMPLEMENTED when we try to KEXINIT during authentication. [originally from svn r9609]
This commit is contained in:
Ben Harris
parent
4e5012aeda
commit
8e0ab8be59
176
ssh.c
176
ssh.c
@ -960,6 +960,7 @@ struct ssh_tag {
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* indications from a request.
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*/
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struct queued_handler *qhead, *qtail;
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handler_fn_t q_saved_handler1, q_saved_handler2;
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/*
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* This module deals with sending keepalives.
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@ -4353,27 +4354,26 @@ static void ssh_queueing_handler(Ssh ssh, struct Packet *pktin)
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if (qh->msg1 > 0) {
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assert(ssh->packet_dispatch[qh->msg1] == ssh_queueing_handler);
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ssh->packet_dispatch[qh->msg1] = NULL;
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ssh->packet_dispatch[qh->msg1] = ssh->q_saved_handler1;
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}
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if (qh->msg2 > 0) {
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assert(ssh->packet_dispatch[qh->msg2] == ssh_queueing_handler);
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ssh->packet_dispatch[qh->msg2] = NULL;
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ssh->packet_dispatch[qh->msg2] = ssh->q_saved_handler2;
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}
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if (qh->next) {
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ssh->qhead = qh->next;
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if (ssh->qhead->msg1 > 0) {
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assert(ssh->packet_dispatch[ssh->qhead->msg1] == NULL);
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ssh->q_saved_handler1 = ssh->packet_dispatch[ssh->qhead->msg1];
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ssh->packet_dispatch[ssh->qhead->msg1] = ssh_queueing_handler;
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}
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if (ssh->qhead->msg2 > 0) {
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assert(ssh->packet_dispatch[ssh->qhead->msg2] == NULL);
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ssh->q_saved_handler2 = ssh->packet_dispatch[ssh->qhead->msg2];
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ssh->packet_dispatch[ssh->qhead->msg2] = ssh_queueing_handler;
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}
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} else {
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ssh->qhead = ssh->qtail = NULL;
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ssh->packet_dispatch[pktin->type] = NULL;
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}
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qh->handler(ssh, pktin, qh->ctx);
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@ -4397,11 +4397,11 @@ static void ssh_queue_handler(Ssh ssh, int msg1, int msg2,
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ssh->qhead = qh;
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if (qh->msg1 > 0) {
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assert(ssh->packet_dispatch[qh->msg1] == NULL);
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ssh->q_saved_handler1 = ssh->packet_dispatch[ssh->qhead->msg1];
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ssh->packet_dispatch[qh->msg1] = ssh_queueing_handler;
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}
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if (qh->msg2 > 0) {
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assert(ssh->packet_dispatch[qh->msg2] == NULL);
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ssh->q_saved_handler2 = ssh->packet_dispatch[ssh->qhead->msg2];
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ssh->packet_dispatch[qh->msg2] = ssh_queueing_handler;
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}
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} else {
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@ -6409,19 +6409,6 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
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ssh->next_rekey = schedule_timer(conf_get_int(ssh->conf, CONF_ssh_rekey_time)*60*TICKSPERSEC,
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ssh2_timer, ssh);
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/*
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* If this is the first key exchange phase, we must pass the
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* SSH2_MSG_NEWKEYS packet to the next layer, not because it
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* wants to see it but because it will need time to initialise
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* itself before it sees an actual packet. In subsequent key
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* exchange phases, we don't pass SSH2_MSG_NEWKEYS on, because
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* it would only confuse the layer above.
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*/
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if (s->activated_authconn) {
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crReturn(0);
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}
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s->activated_authconn = TRUE;
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/*
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* Now we're encrypting. Begin returning 1 to the protocol main
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* function so that other things can run on top of the
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@ -6440,6 +6427,13 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
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while (!((pktin && pktin->type == SSH2_MSG_KEXINIT) ||
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(!pktin && inlen < 0))) {
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wait_for_rekey:
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if (!ssh->protocol_initial_phase_done) {
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ssh->protocol_initial_phase_done = TRUE;
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/*
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* Allow authconn to initialise itself.
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*/
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do_ssh2_authconn(ssh, NULL, 0, NULL);
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}
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crReturn(1);
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}
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if (pktin) {
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@ -7474,6 +7468,11 @@ static void ssh2_send_ttymode(void *data, char *mode, char *val)
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/*
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* Handle the SSH-2 userauth and connection layers.
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*/
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static void ssh2_msg_authconn(Ssh ssh, struct Packet *pktin)
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{
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do_ssh2_authconn(ssh, NULL, 0, pktin);
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}
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static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
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struct Packet *pktin)
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{
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@ -7536,6 +7535,31 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
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crBeginState;
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/* Register as a handler for all the messages this coroutine handles. */
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ssh->packet_dispatch[SSH2_MSG_SERVICE_ACCEPT] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_REQUEST] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_FAILURE] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_SUCCESS] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_BANNER] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_PK_OK] = ssh2_msg_authconn;
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/* ssh->packet_dispatch[SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ] = ssh2_msg_authconn; duplicate case value */
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/* ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_REQUEST] = ssh2_msg_authconn; duplicate case value */
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_RESPONSE] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_GLOBAL_REQUEST] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_REQUEST_SUCCESS] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_REQUEST_FAILURE] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_CONFIRMATION] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_FAILURE] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_WINDOW_ADJUST] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_DATA] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_EXTENDED_DATA] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_EOF] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_CLOSE] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_REQUEST] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_SUCCESS] = ssh2_msg_authconn;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_FAILURE] = ssh2_msg_authconn;
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s->done_service_req = FALSE;
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s->we_are_in = s->userauth_success = FALSE;
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#ifndef NO_GSSAPI
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@ -9367,6 +9391,24 @@ static void ssh2_msg_debug(Ssh ssh, struct Packet *pktin)
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logeventf(ssh, "Remote debug message: %.*s", msglen, msg);
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}
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static void ssh2_msg_transport(Ssh ssh, struct Packet *pktin)
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{
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do_ssh2_transport(ssh, NULL, 0, pktin);
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}
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/*
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* Called if we receive a packet that isn't allowed by the protocol.
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* This only applies to packets whose meaning PuTTY understands.
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* Entirely unknown packets are handled below.
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*/
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static void ssh2_msg_unexpected(Ssh ssh, struct Packet *pktin)
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{
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char *buf = dupprintf("Server protocol violation: unexpected %s packet",
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ssh2_pkt_type(ssh->pkt_kctx, ssh->pkt_actx,
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pktin->type));
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ssh_disconnect(ssh, NULL, buf, SSH2_DISCONNECT_PROTOCOL_ERROR, FALSE);
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}
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static void ssh2_msg_something_unimplemented(Ssh ssh, struct Packet *pktin)
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{
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struct Packet *pktout;
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@ -9393,45 +9435,47 @@ static void ssh2_protocol_setup(Ssh ssh)
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ssh->packet_dispatch[i] = ssh2_msg_something_unimplemented;
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/*
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* Any message we actually understand, we set to NULL so that
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* the coroutines will get it.
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* Initially, we only accept transport messages (and a few generic
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* ones). do_ssh2_authconn will add more when it starts.
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* Messages that are understood but not currently acceptable go to
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* ssh2_msg_unexpected.
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*/
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ssh->packet_dispatch[SSH2_MSG_UNIMPLEMENTED] = NULL;
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ssh->packet_dispatch[SSH2_MSG_SERVICE_REQUEST] = NULL;
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ssh->packet_dispatch[SSH2_MSG_SERVICE_ACCEPT] = NULL;
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ssh->packet_dispatch[SSH2_MSG_KEXINIT] = NULL;
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ssh->packet_dispatch[SSH2_MSG_NEWKEYS] = NULL;
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ssh->packet_dispatch[SSH2_MSG_KEXDH_INIT] = NULL;
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ssh->packet_dispatch[SSH2_MSG_KEXDH_REPLY] = NULL;
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/* ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_REQUEST] = NULL; duplicate case value */
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/* ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_GROUP] = NULL; duplicate case value */
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ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_INIT] = NULL;
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ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_REPLY] = NULL;
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_REQUEST] = NULL;
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_FAILURE] = NULL;
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_SUCCESS] = NULL;
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_BANNER] = NULL;
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_PK_OK] = NULL;
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/* ssh->packet_dispatch[SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ] = NULL; duplicate case value */
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/* ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_REQUEST] = NULL; duplicate case value */
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_RESPONSE] = NULL;
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ssh->packet_dispatch[SSH2_MSG_GLOBAL_REQUEST] = NULL;
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ssh->packet_dispatch[SSH2_MSG_REQUEST_SUCCESS] = NULL;
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ssh->packet_dispatch[SSH2_MSG_REQUEST_FAILURE] = NULL;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN] = NULL;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_CONFIRMATION] = NULL;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_FAILURE] = NULL;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_WINDOW_ADJUST] = NULL;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_DATA] = NULL;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_EXTENDED_DATA] = NULL;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_EOF] = NULL;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_CLOSE] = NULL;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_REQUEST] = NULL;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_SUCCESS] = NULL;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_FAILURE] = NULL;
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ssh->packet_dispatch[SSH2_MSG_UNIMPLEMENTED] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_SERVICE_REQUEST] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_SERVICE_ACCEPT] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_KEXINIT] = ssh2_msg_transport;
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ssh->packet_dispatch[SSH2_MSG_NEWKEYS] = ssh2_msg_transport;
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ssh->packet_dispatch[SSH2_MSG_KEXDH_INIT] = ssh2_msg_transport;
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ssh->packet_dispatch[SSH2_MSG_KEXDH_REPLY] = ssh2_msg_transport;
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/* ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_REQUEST] = ssh2_msg_transport; duplicate case value */
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/* ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_GROUP] = ssh2_msg_transport; duplicate case value */
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ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_INIT] = ssh2_msg_transport;
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ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_REPLY] = ssh2_msg_transport;
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_REQUEST] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_FAILURE] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_SUCCESS] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_BANNER] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_PK_OK] = ssh2_msg_unexpected;
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/* ssh->packet_dispatch[SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ] = ssh2_msg_unexpected; duplicate case value */
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/* ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_REQUEST] = ssh2_msg_unexpected; duplicate case value */
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ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_RESPONSE] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_GLOBAL_REQUEST] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_REQUEST_SUCCESS] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_REQUEST_FAILURE] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_CONFIRMATION] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_FAILURE] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_WINDOW_ADJUST] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_DATA] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_EXTENDED_DATA] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_EOF] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_CLOSE] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_REQUEST] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_SUCCESS] = ssh2_msg_unexpected;
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ssh->packet_dispatch[SSH2_MSG_CHANNEL_FAILURE] = ssh2_msg_unexpected;
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/*
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* These special message types we install handlers for.
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* These messages have a special handler from the start.
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*/
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ssh->packet_dispatch[SSH2_MSG_DISCONNECT] = ssh2_msg_disconnect;
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ssh->packet_dispatch[SSH2_MSG_IGNORE] = ssh_msg_ignore; /* shared with SSH-1 */
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@ -9466,24 +9510,12 @@ static void ssh2_protocol(Ssh ssh, void *vin, int inlen,
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do_ssh2_transport(ssh, "too much data received", -1, NULL);
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}
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if (pktin && ssh->packet_dispatch[pktin->type]) {
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if (pktin)
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ssh->packet_dispatch[pktin->type](ssh, pktin);
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return;
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}
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if (!ssh->protocol_initial_phase_done ||
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(pktin && pktin->type >= 20 && pktin->type < 50)) {
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if (do_ssh2_transport(ssh, in, inlen, pktin) &&
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!ssh->protocol_initial_phase_done) {
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ssh->protocol_initial_phase_done = TRUE;
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/*
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* Allow authconn to initialise itself.
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*/
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do_ssh2_authconn(ssh, NULL, 0, NULL);
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}
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} else {
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else if (!ssh->protocol_initial_phase_done)
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do_ssh2_transport(ssh, in, inlen, pktin);
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else
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do_ssh2_authconn(ssh, in, inlen, pktin);
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}
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}
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static void ssh_cache_conf_values(Ssh ssh)
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