From: ben Date: Tue, 21 Aug 2012 22:04:56 +0000 (+0000) Subject: Reworking of packet delivery to coroutines in SSH-2. X-Git-Url: https://git.distorted.org.uk/~mdw/sgt/putty/commitdiff_plain/bc0741471148b6f7227e73367f0bdaba12e23804 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. git-svn-id: svn://svn.tartarus.org/sgt/putty@9609 cda61777-01e9-0310-a592-d414129be87e --- diff --git a/ssh.c b/ssh.c index 1ef80b06..ae49ba1d 100644 --- a/ssh.c +++ b/ssh.c @@ -960,6 +960,7 @@ struct ssh_tag { * indications from a request. */ struct queued_handler *qhead, *qtail; + handler_fn_t q_saved_handler1, q_saved_handler2; /* * This module deals with sending keepalives. @@ -4353,27 +4354,26 @@ static void ssh_queueing_handler(Ssh ssh, struct Packet *pktin) if (qh->msg1 > 0) { assert(ssh->packet_dispatch[qh->msg1] == ssh_queueing_handler); - ssh->packet_dispatch[qh->msg1] = NULL; + ssh->packet_dispatch[qh->msg1] = ssh->q_saved_handler1; } if (qh->msg2 > 0) { assert(ssh->packet_dispatch[qh->msg2] == ssh_queueing_handler); - ssh->packet_dispatch[qh->msg2] = NULL; + ssh->packet_dispatch[qh->msg2] = ssh->q_saved_handler2; } if (qh->next) { ssh->qhead = qh->next; if (ssh->qhead->msg1 > 0) { - assert(ssh->packet_dispatch[ssh->qhead->msg1] == NULL); + ssh->q_saved_handler1 = ssh->packet_dispatch[ssh->qhead->msg1]; ssh->packet_dispatch[ssh->qhead->msg1] = ssh_queueing_handler; } if (ssh->qhead->msg2 > 0) { - assert(ssh->packet_dispatch[ssh->qhead->msg2] == NULL); + ssh->q_saved_handler2 = ssh->packet_dispatch[ssh->qhead->msg2]; ssh->packet_dispatch[ssh->qhead->msg2] = ssh_queueing_handler; } } else { ssh->qhead = ssh->qtail = NULL; - ssh->packet_dispatch[pktin->type] = NULL; } qh->handler(ssh, pktin, qh->ctx); @@ -4397,11 +4397,11 @@ static void ssh_queue_handler(Ssh ssh, int msg1, int msg2, ssh->qhead = qh; if (qh->msg1 > 0) { - assert(ssh->packet_dispatch[qh->msg1] == NULL); + ssh->q_saved_handler1 = ssh->packet_dispatch[ssh->qhead->msg1]; ssh->packet_dispatch[qh->msg1] = ssh_queueing_handler; } if (qh->msg2 > 0) { - assert(ssh->packet_dispatch[qh->msg2] == NULL); + ssh->q_saved_handler2 = ssh->packet_dispatch[ssh->qhead->msg2]; ssh->packet_dispatch[qh->msg2] = ssh_queueing_handler; } } else { @@ -6410,19 +6410,6 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen, ssh2_timer, ssh); /* - * If this is the first key exchange phase, we must pass the - * SSH2_MSG_NEWKEYS packet to the next layer, not because it - * wants to see it but because it will need time to initialise - * itself before it sees an actual packet. In subsequent key - * exchange phases, we don't pass SSH2_MSG_NEWKEYS on, because - * it would only confuse the layer above. - */ - if (s->activated_authconn) { - crReturn(0); - } - s->activated_authconn = TRUE; - - /* * Now we're encrypting. Begin returning 1 to the protocol main * function so that other things can run on top of the * transport. If we ever see a KEXINIT, we must go back to the @@ -6440,6 +6427,13 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen, while (!((pktin && pktin->type == SSH2_MSG_KEXINIT) || (!pktin && inlen < 0))) { wait_for_rekey: + if (!ssh->protocol_initial_phase_done) { + ssh->protocol_initial_phase_done = TRUE; + /* + * Allow authconn to initialise itself. + */ + do_ssh2_authconn(ssh, NULL, 0, NULL); + } crReturn(1); } if (pktin) { @@ -7474,6 +7468,11 @@ static void ssh2_send_ttymode(void *data, char *mode, char *val) /* * Handle the SSH-2 userauth and connection layers. */ +static void ssh2_msg_authconn(Ssh ssh, struct Packet *pktin) +{ + do_ssh2_authconn(ssh, NULL, 0, pktin); +} + static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, struct Packet *pktin) { @@ -7536,6 +7535,31 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, crBeginState; + /* Register as a handler for all the messages this coroutine handles. */ + ssh->packet_dispatch[SSH2_MSG_SERVICE_ACCEPT] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_USERAUTH_REQUEST] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_USERAUTH_FAILURE] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_USERAUTH_SUCCESS] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_USERAUTH_BANNER] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_USERAUTH_PK_OK] = ssh2_msg_authconn; + /* ssh->packet_dispatch[SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ] = ssh2_msg_authconn; duplicate case value */ + /* ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_REQUEST] = ssh2_msg_authconn; duplicate case value */ + ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_RESPONSE] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_GLOBAL_REQUEST] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_REQUEST_SUCCESS] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_REQUEST_FAILURE] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_CONFIRMATION] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_FAILURE] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_WINDOW_ADJUST] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_DATA] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_EXTENDED_DATA] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_EOF] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_CLOSE] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_REQUEST] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_SUCCESS] = ssh2_msg_authconn; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_FAILURE] = ssh2_msg_authconn; + s->done_service_req = FALSE; s->we_are_in = s->userauth_success = FALSE; #ifndef NO_GSSAPI @@ -9367,6 +9391,24 @@ static void ssh2_msg_debug(Ssh ssh, struct Packet *pktin) logeventf(ssh, "Remote debug message: %.*s", msglen, msg); } +static void ssh2_msg_transport(Ssh ssh, struct Packet *pktin) +{ + do_ssh2_transport(ssh, NULL, 0, pktin); +} + +/* + * Called if we receive a packet that isn't allowed by the protocol. + * This only applies to packets whose meaning PuTTY understands. + * Entirely unknown packets are handled below. + */ +static void ssh2_msg_unexpected(Ssh ssh, struct Packet *pktin) +{ + char *buf = dupprintf("Server protocol violation: unexpected %s packet", + ssh2_pkt_type(ssh->pkt_kctx, ssh->pkt_actx, + pktin->type)); + ssh_disconnect(ssh, NULL, buf, SSH2_DISCONNECT_PROTOCOL_ERROR, FALSE); +} + static void ssh2_msg_something_unimplemented(Ssh ssh, struct Packet *pktin) { struct Packet *pktout; @@ -9393,45 +9435,47 @@ static void ssh2_protocol_setup(Ssh ssh) ssh->packet_dispatch[i] = ssh2_msg_something_unimplemented; /* - * Any message we actually understand, we set to NULL so that - * the coroutines will get it. + * Initially, we only accept transport messages (and a few generic + * ones). do_ssh2_authconn will add more when it starts. + * Messages that are understood but not currently acceptable go to + * ssh2_msg_unexpected. */ - ssh->packet_dispatch[SSH2_MSG_UNIMPLEMENTED] = NULL; - ssh->packet_dispatch[SSH2_MSG_SERVICE_REQUEST] = NULL; - ssh->packet_dispatch[SSH2_MSG_SERVICE_ACCEPT] = NULL; - ssh->packet_dispatch[SSH2_MSG_KEXINIT] = NULL; - ssh->packet_dispatch[SSH2_MSG_NEWKEYS] = NULL; - ssh->packet_dispatch[SSH2_MSG_KEXDH_INIT] = NULL; - ssh->packet_dispatch[SSH2_MSG_KEXDH_REPLY] = NULL; - /* ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_REQUEST] = NULL; duplicate case value */ - /* ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_GROUP] = NULL; duplicate case value */ - ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_INIT] = NULL; - ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_REPLY] = NULL; - ssh->packet_dispatch[SSH2_MSG_USERAUTH_REQUEST] = NULL; - ssh->packet_dispatch[SSH2_MSG_USERAUTH_FAILURE] = NULL; - ssh->packet_dispatch[SSH2_MSG_USERAUTH_SUCCESS] = NULL; - ssh->packet_dispatch[SSH2_MSG_USERAUTH_BANNER] = NULL; - ssh->packet_dispatch[SSH2_MSG_USERAUTH_PK_OK] = NULL; - /* ssh->packet_dispatch[SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ] = NULL; duplicate case value */ - /* ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_REQUEST] = NULL; duplicate case value */ - ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_RESPONSE] = NULL; - ssh->packet_dispatch[SSH2_MSG_GLOBAL_REQUEST] = NULL; - ssh->packet_dispatch[SSH2_MSG_REQUEST_SUCCESS] = NULL; - ssh->packet_dispatch[SSH2_MSG_REQUEST_FAILURE] = NULL; - ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN] = NULL; - ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_CONFIRMATION] = NULL; - ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_FAILURE] = NULL; - ssh->packet_dispatch[SSH2_MSG_CHANNEL_WINDOW_ADJUST] = NULL; - ssh->packet_dispatch[SSH2_MSG_CHANNEL_DATA] = NULL; - ssh->packet_dispatch[SSH2_MSG_CHANNEL_EXTENDED_DATA] = NULL; - ssh->packet_dispatch[SSH2_MSG_CHANNEL_EOF] = NULL; - ssh->packet_dispatch[SSH2_MSG_CHANNEL_CLOSE] = NULL; - ssh->packet_dispatch[SSH2_MSG_CHANNEL_REQUEST] = NULL; - ssh->packet_dispatch[SSH2_MSG_CHANNEL_SUCCESS] = NULL; - ssh->packet_dispatch[SSH2_MSG_CHANNEL_FAILURE] = NULL; + ssh->packet_dispatch[SSH2_MSG_UNIMPLEMENTED] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_SERVICE_REQUEST] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_SERVICE_ACCEPT] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_KEXINIT] = ssh2_msg_transport; + ssh->packet_dispatch[SSH2_MSG_NEWKEYS] = ssh2_msg_transport; + ssh->packet_dispatch[SSH2_MSG_KEXDH_INIT] = ssh2_msg_transport; + ssh->packet_dispatch[SSH2_MSG_KEXDH_REPLY] = ssh2_msg_transport; + /* ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_REQUEST] = ssh2_msg_transport; duplicate case value */ + /* ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_GROUP] = ssh2_msg_transport; duplicate case value */ + ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_INIT] = ssh2_msg_transport; + ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_REPLY] = ssh2_msg_transport; + ssh->packet_dispatch[SSH2_MSG_USERAUTH_REQUEST] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_USERAUTH_FAILURE] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_USERAUTH_SUCCESS] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_USERAUTH_BANNER] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_USERAUTH_PK_OK] = ssh2_msg_unexpected; + /* ssh->packet_dispatch[SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ] = ssh2_msg_unexpected; duplicate case value */ + /* ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_REQUEST] = ssh2_msg_unexpected; duplicate case value */ + ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_RESPONSE] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_GLOBAL_REQUEST] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_REQUEST_SUCCESS] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_REQUEST_FAILURE] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_CONFIRMATION] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_FAILURE] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_WINDOW_ADJUST] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_DATA] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_EXTENDED_DATA] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_EOF] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_CLOSE] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_REQUEST] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_SUCCESS] = ssh2_msg_unexpected; + ssh->packet_dispatch[SSH2_MSG_CHANNEL_FAILURE] = ssh2_msg_unexpected; /* - * These special message types we install handlers for. + * These messages have a special handler from the start. */ ssh->packet_dispatch[SSH2_MSG_DISCONNECT] = ssh2_msg_disconnect; ssh->packet_dispatch[SSH2_MSG_IGNORE] = ssh_msg_ignore; /* shared with SSH-1 */ @@ -9466,24 +9510,12 @@ static void ssh2_protocol(Ssh ssh, void *vin, int inlen, do_ssh2_transport(ssh, "too much data received", -1, NULL); } - if (pktin && ssh->packet_dispatch[pktin->type]) { + if (pktin) ssh->packet_dispatch[pktin->type](ssh, pktin); - return; - } - - if (!ssh->protocol_initial_phase_done || - (pktin && pktin->type >= 20 && pktin->type < 50)) { - if (do_ssh2_transport(ssh, in, inlen, pktin) && - !ssh->protocol_initial_phase_done) { - ssh->protocol_initial_phase_done = TRUE; - /* - * Allow authconn to initialise itself. - */ - do_ssh2_authconn(ssh, NULL, 0, NULL); - } - } else { + else if (!ssh->protocol_initial_phase_done) + do_ssh2_transport(ssh, in, inlen, pktin); + else do_ssh2_authconn(ssh, in, inlen, pktin); - } } static void ssh_cache_conf_values(Ssh ssh)