diff options
Diffstat (limited to 'ssh2userauth.c')
| -rw-r--r-- | ssh2userauth.c | 1973 |
1 files changed, 0 insertions, 1973 deletions
diff --git a/ssh2userauth.c b/ssh2userauth.c deleted file mode 100644 index 451d5abe..00000000 --- a/ssh2userauth.c +++ /dev/null @@ -1,1973 +0,0 @@ -/* - * Packet protocol layer for the client side of the SSH-2 userauth - * protocol (RFC 4252). - */ - -#include <assert.h> - -#include "putty.h" -#include "ssh.h" -#include "sshbpp.h" -#include "sshppl.h" -#include "sshcr.h" - -#ifndef NO_GSSAPI -#include "sshgssc.h" -#include "sshgss.h" -#endif - -#define BANNER_LIMIT 131072 - -typedef struct agent_key { - strbuf *blob, *comment; - ptrlen algorithm; -} agent_key; - -struct ssh2_userauth_state { - int crState; - - PacketProtocolLayer *transport_layer, *successor_layer; - Filename *keyfile; - bool show_banner, tryagent, notrivialauth, change_username; - char *hostname, *fullhostname; - char *default_username; - bool try_ki_auth, try_gssapi_auth, try_gssapi_kex_auth, gssapi_fwd; - - ptrlen session_id; - enum { - AUTH_TYPE_NONE, - AUTH_TYPE_PUBLICKEY, - AUTH_TYPE_PUBLICKEY_OFFER_LOUD, - AUTH_TYPE_PUBLICKEY_OFFER_QUIET, - AUTH_TYPE_PASSWORD, - AUTH_TYPE_GSSAPI, /* always QUIET */ - AUTH_TYPE_KEYBOARD_INTERACTIVE, - AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET - } type; - bool need_pw, can_pubkey, can_passwd, can_keyb_inter; - int userpass_ret; - bool tried_pubkey_config, done_agent; - struct ssh_connection_shared_gss_state *shgss; -#ifndef NO_GSSAPI - bool can_gssapi; - bool can_gssapi_keyex_auth; - bool tried_gssapi; - bool tried_gssapi_keyex_auth; - time_t gss_cred_expiry; - Ssh_gss_buf gss_buf; - Ssh_gss_buf gss_rcvtok, gss_sndtok; - Ssh_gss_stat gss_stat; -#endif - bool suppress_wait_for_response_packet; - strbuf *last_methods_string; - bool kbd_inter_refused; - prompts_t *cur_prompt; - uint32_t num_prompts; - const char *username; - char *locally_allocated_username; - char *password; - bool got_username; - strbuf *publickey_blob; - bool privatekey_available, privatekey_encrypted; - char *publickey_algorithm; - char *publickey_comment; - void *agent_response_to_free; - ptrlen agent_response; - BinarySource asrc[1]; /* for reading SSH agent response */ - size_t agent_keys_len; - agent_key *agent_keys; - size_t agent_key_index, agent_key_limit; - ptrlen agent_keyalg; - unsigned signflags; - int len; - PktOut *pktout; - bool want_user_input; - bool is_trivial_auth; - - agent_pending_query *auth_agent_query; - bufchain banner; - bufchain_sink banner_bs; - StripCtrlChars *banner_scc; - bool banner_scc_initialised; - - StripCtrlChars *ki_scc; - bool ki_scc_initialised; - bool ki_printed_header; - - PacketProtocolLayer ppl; -}; - -static void ssh2_userauth_free(PacketProtocolLayer *); -static void ssh2_userauth_process_queue(PacketProtocolLayer *); -static bool ssh2_userauth_get_specials( - PacketProtocolLayer *ppl, add_special_fn_t add_special, void *ctx); -static void ssh2_userauth_special_cmd(PacketProtocolLayer *ppl, - SessionSpecialCode code, int arg); -static bool ssh2_userauth_want_user_input(PacketProtocolLayer *ppl); -static void ssh2_userauth_got_user_input(PacketProtocolLayer *ppl); -static void ssh2_userauth_reconfigure(PacketProtocolLayer *ppl, Conf *conf); - -static void ssh2_userauth_agent_query(struct ssh2_userauth_state *, strbuf *); -static void ssh2_userauth_agent_callback(void *, void *, int); -static void ssh2_userauth_add_sigblob( - struct ssh2_userauth_state *s, PktOut *pkt, ptrlen pkblob, ptrlen sigblob); -static void ssh2_userauth_add_session_id( - struct ssh2_userauth_state *s, strbuf *sigdata); -#ifndef NO_GSSAPI -static PktOut *ssh2_userauth_gss_packet( - struct ssh2_userauth_state *s, const char *authtype); -#endif -static void ssh2_userauth_antispoof_msg( - struct ssh2_userauth_state *s, const char *msg); - -static const PacketProtocolLayerVtable ssh2_userauth_vtable = { - .free = ssh2_userauth_free, - .process_queue = ssh2_userauth_process_queue, - .get_specials = ssh2_userauth_get_specials, - .special_cmd = ssh2_userauth_special_cmd, - .want_user_input = ssh2_userauth_want_user_input, - .got_user_input = ssh2_userauth_got_user_input, - .reconfigure = ssh2_userauth_reconfigure, - .queued_data_size = ssh_ppl_default_queued_data_size, - .name = "ssh-userauth", -}; - -PacketProtocolLayer *ssh2_userauth_new( - PacketProtocolLayer *successor_layer, - const char *hostname, const char *fullhostname, - Filename *keyfile, bool show_banner, bool tryagent, bool notrivialauth, - const char *default_username, bool change_username, - bool try_ki_auth, bool try_gssapi_auth, bool try_gssapi_kex_auth, - bool gssapi_fwd, struct ssh_connection_shared_gss_state *shgss) -{ - struct ssh2_userauth_state *s = snew(struct ssh2_userauth_state); - memset(s, 0, sizeof(*s)); - s->ppl.vt = &ssh2_userauth_vtable; - - s->successor_layer = successor_layer; - s->hostname = dupstr(hostname); - s->fullhostname = dupstr(fullhostname); - s->keyfile = filename_copy(keyfile); - s->show_banner = show_banner; - s->tryagent = tryagent; - s->notrivialauth = notrivialauth; - s->default_username = dupstr(default_username); - s->change_username = change_username; - s->try_ki_auth = try_ki_auth; - s->try_gssapi_auth = try_gssapi_auth; - s->try_gssapi_kex_auth = try_gssapi_kex_auth; - s->gssapi_fwd = gssapi_fwd; - s->shgss = shgss; - s->last_methods_string = strbuf_new(); - s->is_trivial_auth = true; - bufchain_init(&s->banner); - bufchain_sink_init(&s->banner_bs, &s->banner); - - return &s->ppl; -} - -void ssh2_userauth_set_transport_layer(PacketProtocolLayer *userauth, - PacketProtocolLayer *transport) -{ - struct ssh2_userauth_state *s = - container_of(userauth, struct ssh2_userauth_state, ppl); - s->transport_layer = transport; -} - -static void ssh2_userauth_free(PacketProtocolLayer *ppl) -{ - struct ssh2_userauth_state *s = - container_of(ppl, struct ssh2_userauth_state, ppl); - bufchain_clear(&s->banner); - - if (s->successor_layer) - ssh_ppl_free(s->successor_layer); - - if (s->agent_keys) { - for (size_t i = 0; i < s->agent_keys_len; i++) { - strbuf_free(s->agent_keys[i].blob); - strbuf_free(s->agent_keys[i].comment); - } - sfree(s->agent_keys); - } - sfree(s->agent_response_to_free); - if (s->auth_agent_query) - agent_cancel_query(s->auth_agent_query); - filename_free(s->keyfile); - sfree(s->default_username); - sfree(s->locally_allocated_username); - sfree(s->hostname); - sfree(s->fullhostname); - sfree(s->publickey_comment); - sfree(s->publickey_algorithm); - if (s->publickey_blob) - strbuf_free(s->publickey_blob); - strbuf_free(s->last_methods_string); - if (s->banner_scc) - stripctrl_free(s->banner_scc); - if (s->ki_scc) - stripctrl_free(s->ki_scc); - sfree(s); -} - -static void ssh2_userauth_filter_queue(struct ssh2_userauth_state *s) -{ - PktIn *pktin; - ptrlen string; - - while ((pktin = pq_peek(s->ppl.in_pq)) != NULL) { - switch (pktin->type) { - case SSH2_MSG_USERAUTH_BANNER: - if (!s->show_banner) { - pq_pop(s->ppl.in_pq); - break; - } - - string = get_string(pktin); - if (string.len > BANNER_LIMIT - bufchain_size(&s->banner)) - string.len = BANNER_LIMIT - bufchain_size(&s->banner); - if (!s->banner_scc_initialised) { - s->banner_scc = seat_stripctrl_new( - s->ppl.seat, BinarySink_UPCAST(&s->banner_bs), SIC_BANNER); - if (s->banner_scc) - stripctrl_enable_line_limiting(s->banner_scc); - s->banner_scc_initialised = true; - } - if (s->banner_scc) - put_datapl(s->banner_scc, string); - else - put_datapl(&s->banner_bs, string); - pq_pop(s->ppl.in_pq); - break; - - default: - return; - } - } -} - -static PktIn *ssh2_userauth_pop(struct ssh2_userauth_state *s) -{ - ssh2_userauth_filter_queue(s); - return pq_pop(s->ppl.in_pq); -} - -static void ssh2_userauth_process_queue(PacketProtocolLayer *ppl) -{ - struct ssh2_userauth_state *s = - container_of(ppl, struct ssh2_userauth_state, ppl); - PktIn *pktin; - - ssh2_userauth_filter_queue(s); /* no matter why we were called */ - - crBegin(s->crState); - -#ifndef NO_GSSAPI - s->tried_gssapi = false; - s->tried_gssapi_keyex_auth = false; -#endif - - /* - * Misc one-time setup for authentication. - */ - s->publickey_blob = NULL; - s->session_id = ssh2_transport_get_session_id(s->transport_layer); - - /* - * Load the public half of any configured public key file for - * later use. - */ - if (!filename_is_null(s->keyfile)) { - int keytype; - ppl_logevent("Reading key file \"%s\"", - filename_to_str(s->keyfile)); - keytype = key_type(s->keyfile); - if (keytype == SSH_KEYTYPE_SSH2 || - keytype == SSH_KEYTYPE_SSH2_PUBLIC_RFC4716 || - keytype == SSH_KEYTYPE_SSH2_PUBLIC_OPENSSH) { - const char *error; - s->publickey_blob = strbuf_new(); - if (ppk_loadpub_f(s->keyfile, &s->publickey_algorithm, - BinarySink_UPCAST(s->publickey_blob), - &s->publickey_comment, &error)) { - s->privatekey_available = (keytype == SSH_KEYTYPE_SSH2); - if (!s->privatekey_available) - ppl_logevent("Key file contains public key only"); - s->privatekey_encrypted = ppk_encrypted_f(s->keyfile, NULL); - } else { - ppl_logevent("Unable to load key (%s)", error); - ppl_printf("Unable to load key file \"%s\" (%s)\r\n", - filename_to_str(s->keyfile), error); - strbuf_free(s->publickey_blob); - s->publickey_blob = NULL; - } - } else { - ppl_logevent("Unable to use this key file (%s)", - key_type_to_str(keytype)); - ppl_printf("Unable to use key file \"%s\" (%s)\r\n", - filename_to_str(s->keyfile), - key_type_to_str(keytype)); - s->publickey_blob = NULL; - } - } - - /* - * Find out about any keys Pageant has (but if there's a public - * key configured, filter out all others). - */ - if (s->tryagent && agent_exists()) { - ppl_logevent("Pageant is running. Requesting keys."); - - /* Request the keys held by the agent. */ - { - strbuf *request = strbuf_new_for_agent_query(); - put_byte(request, SSH2_AGENTC_REQUEST_IDENTITIES); - ssh2_userauth_agent_query(s, request); - strbuf_free(request); - crWaitUntilV(!s->auth_agent_query); - } - BinarySource_BARE_INIT_PL(s->asrc, s->agent_response); - - get_uint32(s->asrc); /* skip length field */ - if (get_byte(s->asrc) == SSH2_AGENT_IDENTITIES_ANSWER) { - size_t nkeys = get_uint32(s->asrc); - size_t origpos = s->asrc->pos; - - /* - * Check that the agent response is well formed. - */ - for (size_t i = 0; i < nkeys; i++) { - get_string(s->asrc); /* blob */ - get_string(s->asrc); /* comment */ - if (get_err(s->asrc)) { - ppl_logevent("Pageant's response was truncated"); - goto done_agent_query; - } - } - - /* - * Copy the list of public-key blobs out of the Pageant - * response. - */ - BinarySource_REWIND_TO(s->asrc, origpos); - s->agent_keys_len = nkeys; - s->agent_keys = snewn(s->agent_keys_len, agent_key); - for (size_t i = 0; i < nkeys; i++) { - s->agent_keys[i].blob = strbuf_new(); - put_datapl(s->agent_keys[i].blob, get_string(s->asrc)); - s->agent_keys[i].comment = strbuf_new(); - put_datapl(s->agent_keys[i].comment, get_string(s->asrc)); - - /* Also, extract the algorithm string from the start - * of the public-key blob. */ - BinarySource src[1]; - BinarySource_BARE_INIT_PL(src, ptrlen_from_strbuf( - s->agent_keys[i].blob)); - s->agent_keys[i].algorithm = get_string(src); - } - - ppl_logevent("Pageant has %"SIZEu" SSH-2 keys", nkeys); - - if (s->publickey_blob) { - /* - * If we've been given a specific public key blob, - * filter the list of keys to try from the agent down - * to only that one, or none if it's not there. - */ - ptrlen our_blob = ptrlen_from_strbuf(s->publickey_blob); - size_t i; - - for (i = 0; i < nkeys; i++) { - if (ptrlen_eq_ptrlen(our_blob, ptrlen_from_strbuf( - s->agent_keys[i].blob))) - break; - } - - if (i < nkeys) { - ppl_logevent("Pageant key #%"SIZEu" matches " - "configured key file", i); - s->agent_key_index = i; - s->agent_key_limit = i+1; - } else { - ppl_logevent("Configured key file not in Pageant"); - s->agent_key_index = 0; - s->agent_key_limit = 0; - } - } else { - /* - * Otherwise, try them all. - */ - s->agent_key_index = 0; - s->agent_key_limit = nkeys; - } - } else { - ppl_logevent("Failed to get reply from Pageant"); - } - done_agent_query:; - } - - /* - * We repeat this whole loop, including the username prompt, - * until we manage a successful authentication. If the user - * types the wrong _password_, they can be sent back to the - * beginning to try another username, if this is configured on. - * (If they specify a username in the config, they are never - * asked, even if they do give a wrong password.) - * - * I think this best serves the needs of - * - * - the people who have no configuration, no keys, and just - * want to try repeated (username,password) pairs until they - * type both correctly - * - * - people who have keys and configuration but occasionally - * need to fall back to passwords - * - * - people with a key held in Pageant, who might not have - * logged in to a particular machine before; so they want to - * type a username, and then _either_ their key will be - * accepted, _or_ they will type a password. If they mistype - * the username they will want to be able to get back and - * retype it! - */ - s->got_username = false; - while (1) { - /* - * Get a username. - */ - if (s->got_username && !s->change_username) { - /* - * We got a username last time round this loop, and - * with change_username turned off we don't try to get - * it again. - */ - } else if ((s->username = s->default_username) == NULL) { - s->cur_prompt = new_prompts(); - s->cur_prompt->to_server = true; - s->cur_prompt->from_server = false; - s->cur_prompt->name = dupstr("SSH login name"); - add_prompt(s->cur_prompt, dupstr("login as: "), true); - s->userpass_ret = seat_get_userpass_input( - s->ppl.seat, s->cur_prompt, NULL); - while (1) { - while (s->userpass_ret < 0 && - bufchain_size(s->ppl.user_input) > 0) - s->userpass_ret = seat_get_userpass_input( - s->ppl.seat, s->cur_prompt, s->ppl.user_input); - - if (s->userpass_ret >= 0) - break; - - s->want_user_input = true; - crReturnV; - s->want_user_input = false; - } - if (!s->userpass_ret) { - /* - * seat_get_userpass_input() failed to get a username. - * Terminate. - */ - free_prompts(s->cur_prompt); - ssh_user_close(s->ppl.ssh, "No username provided"); - return; - } - sfree(s->locally_allocated_username); /* for change_username */ - s->username = s->locally_allocated_username = - prompt_get_result(s->cur_prompt->prompts[0]); - free_prompts(s->cur_prompt); - } else { - if (seat_verbose(s->ppl.seat) || seat_interactive(s->ppl.seat)) - ppl_printf("Using username \"%s\".\r\n", s->username); - } - s->got_username = true; - - /* - * Send an authentication request using method "none": (a) - * just in case it succeeds, and (b) so that we know what - * authentication methods we can usefully try next. - */ - s->ppl.bpp->pls->actx = SSH2_PKTCTX_NOAUTH; - - s->pktout = ssh_bpp_new_pktout(s->ppl.bpp, SSH2_MSG_USERAUTH_REQUEST); - put_stringz(s->pktout, s->username); - put_stringz(s->pktout, s->successor_layer->vt->name); - put_stringz(s->pktout, "none"); /* method */ - pq_push(s->ppl.out_pq, s->pktout); - s->type = AUTH_TYPE_NONE; - - s->tried_pubkey_config = false; - s->kbd_inter_refused = false; - s->done_agent = false; - - while (1) { - /* - * Wait for the result of the last authentication request, - * unless the request terminated for some reason on our - * own side. - */ - if (s->suppress_wait_for_response_packet) { - pktin = NULL; - s->suppress_wait_for_response_packet = false; - } else { - crMaybeWaitUntilV((pktin = ssh2_userauth_pop(s)) != NULL); - } - - /* - * Now is a convenient point to spew any banner material - * that we've accumulated. (This should ensure that when - * we exit the auth loop, we haven't any left to deal - * with.) - * - * Don't show the banner if we're operating in non-verbose - * non-interactive mode. (It's probably a script, which - * means nobody will read the banner _anyway_, and - * moreover the printing of the banner will screw up - * processing on the output of (say) plink.) - * - * The banner data has been sanitised already by this - * point, but we still need to precede and follow it with - * anti-spoofing header lines. - */ - if (bufchain_size(&s->banner) && - (seat_verbose(s->ppl.seat) || seat_interactive(s->ppl.seat))) { - if (s->banner_scc) { - ssh2_userauth_antispoof_msg( - s, "Pre-authentication banner message from server:"); - seat_set_trust_status(s->ppl.seat, false); - } - - bool mid_line = false; - while (bufchain_size(&s->banner) > 0) { - ptrlen data = bufchain_prefix(&s->banner); - seat_stderr_pl(s->ppl.seat, data); - mid_line = - (((const char *)data.ptr)[data.len-1] != '\n'); - bufchain_consume(&s->banner, data.len); - } - bufchain_clear(&s->banner); - - if (mid_line) - seat_stderr_pl(s->ppl.seat, PTRLEN_LITERAL("\r\n")); - - if (s->banner_scc) { - seat_set_trust_status(s->ppl.seat, true); - ssh2_userauth_antispoof_msg( - s, "End of banner message from server"); - } - } - - if (pktin && pktin->type == SSH2_MSG_USERAUTH_SUCCESS) { - ppl_logevent("Access granted"); - goto userauth_success; - } - - if (pktin && pktin->type != SSH2_MSG_USERAUTH_FAILURE && - s->type != AUTH_TYPE_GSSAPI) { - ssh_proto_error(s->ppl.ssh, "Received unexpected packet " - "in response to authentication request, " - "type %d (%s)", pktin->type, - ssh2_pkt_type(s->ppl.bpp->pls->kctx, - s->ppl.bpp->pls->actx, - pktin->type)); - return; - } - - /* - * OK, we're now sitting on a USERAUTH_FAILURE message, so - * we can look at the string in it and know what we can - * helpfully try next. - */ - if (pktin && pktin->type == SSH2_MSG_USERAUTH_FAILURE) { - ptrlen methods = get_string(pktin); - bool partial_success = get_bool(pktin); - - if (!partial_success) { - /* - * We have received an unequivocal Access - * Denied. This can translate to a variety of - * messages, or no message at all. - * - * For forms of authentication which are attempted - * implicitly, by which I mean without printing - * anything in the window indicating that we're - * trying them, we should never print 'Access - * denied'. - * - * If we do print a message saying that we're - * attempting some kind of authentication, it's OK - * to print a followup message saying it failed - - * but the message may sometimes be more specific - * than simply 'Access denied'. - * - * Additionally, if we'd just tried password - * authentication, we should break out of this - * whole loop so as to go back to the username - * prompt (iff we're configured to allow - * username change attempts). - */ - if (s->type == AUTH_TYPE_NONE) { - /* do nothing */ - } else if (s->type == AUTH_TYPE_PUBLICKEY_OFFER_LOUD || - s->type == AUTH_TYPE_PUBLICKEY_OFFER_QUIET) { - if (s->type == AUTH_TYPE_PUBLICKEY_OFFER_LOUD) - ppl_printf("Server refused our key\r\n"); - ppl_logevent("Server refused our key"); - } else if (s->type == AUTH_TYPE_PUBLICKEY) { - /* This _shouldn't_ happen except by a - * protocol bug causing client and server to - * disagree on what is a correct signature. */ - ppl_printf("Server refused public-key signature" - " despite accepting key!\r\n"); - ppl_logevent("Server refused public-key signature" - " despite accepting key!"); - } else if (s->type==AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET) { - /* quiet, so no ppl_printf */ - ppl_logevent("Server refused keyboard-interactive " - "authentication"); - } else if (s->type==AUTH_TYPE_GSSAPI) { - /* always quiet, so no ppl_printf */ - /* also, the code down in the GSSAPI block has - * already logged this in the Event Log */ - } else if (s->type == AUTH_TYPE_KEYBOARD_INTERACTIVE) { - ppl_logevent("Keyboard-interactive authentication " - "failed"); - ppl_printf("Access denied\r\n"); - } else { - assert(s->type == AUTH_TYPE_PASSWORD); - ppl_logevent("Password authentication failed"); - ppl_printf("Access denied\r\n"); - - if (s->change_username) { - /* XXX perhaps we should allow - * keyboard-interactive to do this too? */ - goto try_new_username; - } - } - } else { - ppl_printf("Further authentication required\r\n"); - ppl_logevent("Further authentication required"); - } - - /* - * Save the methods string for use in error messages. - */ - strbuf_clear(s->last_methods_string); - put_datapl(s->last_methods_string, methods); - - /* - * Scan it for method identifiers we know about. - */ - bool srv_pubkey = false, srv_passwd = false; - bool srv_keyb_inter = false; -#ifndef NO_GSSAPI - bool srv_gssapi = false, srv_gssapi_keyex_auth = false; -#endif - - for (ptrlen method; get_commasep_word(&methods, &method) ;) { - if (ptrlen_eq_string(method, "publickey")) - srv_pubkey = true; - else if (ptrlen_eq_string(method, "password")) - srv_passwd = true; - else if (ptrlen_eq_string(method, "keyboard-interactive")) - srv_keyb_inter = true; -#ifndef NO_GSSAPI - else if (ptrlen_eq_string(method, "gssapi-with-mic")) - srv_gssapi = true; - else if (ptrlen_eq_string(method, "gssapi-keyex")) - srv_gssapi_keyex_auth = true; -#endif - } - - /* - * And combine those flags with our own configuration - * and context to set the main can_foo variables. - */ - s->can_pubkey = srv_pubkey; - s->can_passwd = srv_passwd; - s->can_keyb_inter = s->try_ki_auth && srv_keyb_inter; -#ifndef NO_GSSAPI - s->can_gssapi = s->try_gssapi_auth && srv_gssapi && - s->shgss->libs->nlibraries > 0; - s->can_gssapi_keyex_auth = s->try_gssapi_kex_auth && - srv_gssapi_keyex_auth && - s->shgss->libs->nlibraries > 0 && s->shgss->ctx; -#endif - } - - s->ppl.bpp->pls->actx = SSH2_PKTCTX_NOAUTH; - -#ifndef NO_GSSAPI - if (s->can_gssapi_keyex_auth && !s->tried_gssapi_keyex_auth) { - - /* gssapi-keyex authentication */ - - s->type = AUTH_TYPE_GSSAPI; - s->tried_gssapi_keyex_auth = true; - s->ppl.bpp->pls->actx = SSH2_PKTCTX_GSSAPI; - - if (s->shgss->lib->gsslogmsg) - ppl_logevent("%s", s->shgss->lib->gsslogmsg); - - ppl_logevent("Trying gssapi-keyex..."); - s->pktout = ssh2_userauth_gss_packet(s, "gssapi-keyex"); - pq_push(s->ppl.out_pq, s->pktout); - s->shgss->lib->release_cred(s->shgss->lib, &s->shgss->ctx); - s->shgss->ctx = NULL; - - continue; - } else -#endif /* NO_GSSAPI */ - - if (s->can_pubkey && !s->done_agent && - s->agent_key_index < s->agent_key_limit) { - - /* - * Attempt public-key authentication using a key from Pageant. - */ - s->agent_keyalg = s->agent_keys[s->agent_key_index].algorithm; - s->signflags = 0; - if (ptrlen_eq_string(s->agent_keyalg, "ssh-rsa")) { - /* Try to upgrade ssh-rsa to one of the rsa-sha2-* family, - * if the server has announced support for them. */ - if (s->ppl.bpp->ext_info_rsa_sha512_ok) { - s->agent_keyalg = PTRLEN_LITERAL("rsa-sha2-512"); - s->signflags = SSH_AGENT_RSA_SHA2_512; - } else if (s->ppl.bpp->ext_info_rsa_sha256_ok) { - s->agent_keyalg = PTRLEN_LITERAL("rsa-sha2-256"); - s->signflags = SSH_AGENT_RSA_SHA2_256; - } - } - - s->ppl.bpp->pls->actx = SSH2_PKTCTX_PUBLICKEY; - - ppl_logevent("Trying Pageant key #%"SIZEu, s->agent_key_index); - - /* See if server will accept it */ - s->pktout = ssh_bpp_new_pktout( - s->ppl.bpp, SSH2_MSG_USERAUTH_REQUEST); - put_stringz(s->pktout, s->username); - put_stringz(s->pktout, s->successor_layer->vt->name); - put_stringz(s->pktout, "publickey"); - /* method */ - put_bool(s->pktout, false); /* no signature included */ - put_stringpl(s->pktout, s->agent_keyalg); - put_stringpl(s->pktout, ptrlen_from_strbuf( - s->agent_keys[s->agent_key_index].blob)); - pq_push(s->ppl.out_pq, s->pktout); - s->type = AUTH_TYPE_PUBLICKEY_OFFER_QUIET; - - crMaybeWaitUntilV((pktin = ssh2_userauth_pop(s)) != NULL); - if (pktin->type != SSH2_MSG_USERAUTH_PK_OK) { - - /* Offer of key refused, presumably via - * USERAUTH_FAILURE. Requeue for the next iteration. */ - pq_push_front(s->ppl.in_pq, pktin); - - } else { - strbuf *agentreq, *sigdata; - ptrlen comment = ptrlen_from_strbuf( - s->agent_keys[s->agent_key_index].comment); - - if (seat_verbose(s->ppl.seat)) - ppl_printf("Authenticating with public key " - "\"%.*s\" from agent\r\n", - PTRLEN_PRINTF(comment)); - - /* - * Server is willing to accept the key. - * Construct a SIGN_REQUEST. - */ - s->pktout = ssh_bpp_new_pktout( - s->ppl.bpp, SSH2_MSG_USERAUTH_REQUEST); - put_stringz(s->pktout, s->username); - put_stringz(s->pktout, s->successor_layer->vt->name); - put_stringz(s->pktout, "publickey"); - /* method */ - put_bool(s->pktout, true); /* signature included */ - put_stringpl(s->pktout, s->agent_keyalg); - put_stringpl(s->pktout, ptrlen_from_strbuf( - s->agent_keys[s->agent_key_index].blob)); - - /* Ask agent for signature. */ - agentreq = strbuf_new_for_agent_query(); - put_byte(agentreq, SSH2_AGENTC_SIGN_REQUEST); - put_stringpl(agentreq, ptrlen_from_strbuf( - s->agent_keys[s->agent_key_index].blob)); - /* Now the data to be signed... */ - sigdata = strbuf_new(); - ssh2_userauth_add_session_id(s, sigdata); - put_data(sigdata, s->pktout->data + 5, - s->pktout->length - 5); - put_stringsb(agentreq, sigdata); - /* And finally the flags word. */ - put_uint32(agentreq, s->signflags); - ssh2_userauth_agent_query(s, agentreq); - strbuf_free(agentreq); - crWaitUntilV(!s->auth_agent_query); - - if (s->agent_response.ptr) { - ptrlen sigblob; - BinarySource src[1]; - BinarySource_BARE_INIT(src, s->agent_response.ptr, - s->agent_response.len); - get_uint32(src); /* skip length field */ - if (get_byte(src) == SSH2_AGENT_SIGN_RESPONSE && - (sigblob = get_string(src), !get_err(src))) { - ppl_logevent("Sending Pageant's response"); - ssh2_userauth_add_sigblob( - s, s->pktout, - ptrlen_from_strbuf( - s->agent_keys[s->agent_key_index].blob), - sigblob); - pq_push(s->ppl.out_pq, s->pktout); - s->type = AUTH_TYPE_PUBLICKEY; - s->is_trivial_auth = false; - } else { - ppl_logevent("Pageant refused signing request"); - ppl_printf("Pageant failed to " - "provide a signature\r\n"); - s->suppress_wait_for_response_packet = true; - ssh_free_pktout(s->pktout); - } - } else { - ppl_logevent("Pageant failed to respond to " - "signing request"); - ppl_printf("Pageant failed to " - "respond to signing request\r\n"); - s->suppress_wait_for_response_packet = true; - ssh_free_pktout(s->pktout); - } - } - - /* Do we have any keys left to try? */ - if (++s->agent_key_index >= s->agent_key_limit) - s->done_agent = true; - - } else if (s->can_pubkey && s->publickey_blob && - s->privatekey_available && !s->tried_pubkey_config) { - - ssh2_userkey *key; /* not live over crReturn */ - char *passphrase; /* not live over crReturn */ - - s->ppl.bpp->pls->actx = SSH2_PKTCTX_PUBLICKEY; - - s->tried_pubkey_config = true; - - /* - * Try the public key supplied in the configuration. - * - * First, try to upgrade its algorithm. - */ - if (!strcmp(s->publickey_algorithm, "ssh-rsa")) { - /* Try to upgrade ssh-rsa to one of the rsa-sha2-* family, - * if the server has announced support for them. */ - if (s->ppl.bpp->ext_info_rsa_sha512_ok) { - sfree(s->publickey_algorithm); - s->publickey_algorithm = dupstr("rsa-sha2-512"); - s->signflags = SSH_AGENT_RSA_SHA2_512; - } else if (s->ppl.bpp->ext_info_rsa_sha256_ok) { - sfree(s->publickey_algorithm); - s->publickey_algorithm = dupstr("rsa-sha2-256"); - s->signflags = SSH_AGENT_RSA_SHA2_256; - } - } - - /* - * Offer the public blob to see if the server is willing to - * accept it. - */ - s->pktout = ssh_bpp_new_pktout( - s->ppl.bpp, SSH2_MSG_USERAUTH_REQUEST); - put_stringz(s->pktout, s->username); - put_stringz(s->pktout, s->successor_layer->vt->name); - put_stringz(s->pktout, "publickey"); /* method */ - put_bool(s->pktout, false); - /* no signature included */ - put_stringz(s->pktout, s->publickey_algorithm); - put_string(s->pktout, s->publickey_blob->s, - s->publickey_blob->len); - pq_push(s->ppl.out_pq, s->pktout); - ppl_logevent("Offered public key"); - - crMaybeWaitUntilV((pktin = ssh2_userauth_pop(s)) != NULL); - if (pktin->type != SSH2_MSG_USERAUTH_PK_OK) { - /* Key refused. Give up. */ - pq_push_front(s->ppl.in_pq, pktin); - s->type = AUTH_TYPE_PUBLICKEY_OFFER_LOUD; - continue; /* process this new message */ - } - ppl_logevent("Offer of public key accepted"); - - /* - * Actually attempt a serious authentication using - * the key. - */ - if (seat_verbose(s->ppl.seat)) - ppl_printf("Authenticating with public key \"%s\"\r\n", - s->publickey_comment); - - key = NULL; - while (!key) { - const char *error; /* not live over crReturn */ - if (s->privatekey_encrypted) { - /* - * Get a passphrase from the user. - */ - s->cur_prompt = new_prompts(); - s->cur_prompt->to_server = false; - s->cur_prompt->from_server = false; - s->cur_prompt->name = dupstr("SSH key passphrase"); - add_prompt(s->cur_prompt, - dupprintf("Passphrase for key \"%s\": ", - s->publickey_comment), - false); - s->userpass_ret = seat_get_userpass_input( - s->ppl.seat, s->cur_prompt, NULL); - while (1) { - while (s->userpass_ret < 0 && - bufchain_size(s->ppl.user_input) > 0) - s->userpass_ret = seat_get_userpass_input( - s->ppl.seat, s->cur_prompt, - s->ppl.user_input); - - if (s->userpass_ret >= 0) - break; - - s->want_user_input = true; - crReturnV; - s->want_user_input = false; - } - if (!s->userpass_ret) { - /* Failed to get a passphrase. Terminate. */ - free_prompts(s->cur_prompt); - ssh_bpp_queue_disconnect( - s->ppl.bpp, "Unable to authenticate", - SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER); - ssh_user_close(s->ppl.ssh, "User aborted at " - "passphrase prompt"); - return; - } - passphrase = - prompt_get_result(s->cur_prompt->prompts[0]); - free_prompts(s->cur_prompt); - } else { - passphrase = NULL; /* no passphrase needed */ - } - - /* - * Try decrypting the key. - */ - key = ppk_load_f(s->keyfile, passphrase, &error); - if (passphrase) { - /* burn the evidence */ - smemclr(passphrase, strlen(passphrase)); - sfree(passphrase); - } - if (key == SSH2_WRONG_PASSPHRASE || key == NULL) { - if (passphrase && - (key == SSH2_WRONG_PASSPHRASE)) { - ppl_printf("Wrong passphrase\r\n"); - key = NULL; - /* and loop again */ - } else { - ppl_printf("Unable to load private key (%s)\r\n", - error); - key = NULL; - s->suppress_wait_for_response_packet = true; - break; /* try something else */ - } - } else { - /* FIXME: if we ever support variable signature - * flags, this is somewhere they'll need to be - * put */ - char *invalid = ssh_key_invalid(key->key, 0); - if (invalid) { - ppl_printf("Cannot use this private key (%s)\r\n", - invalid); - ssh_key_free(key->key); - sfree(key->comment); - sfree(key); - sfree(invalid); - key = NULL; - s->suppress_wait_for_response_packet = true; - break; /* try something else */ - } - } - } - - if (key) { - strbuf *pkblob, *sigdata, *sigblob; - - /* - * We have loaded the private key and the server - * has announced that it's willing to accept it. - * Hallelujah. Generate a signature and send it. - */ - s->pktout = ssh_bpp_new_pktout( - s->ppl.bpp, SSH2_MSG_USERAUTH_REQUEST); - put_stringz(s->pktout, s->username); - put_stringz(s->pktout, s->successor_layer->vt->name); - put_stringz(s->pktout, "publickey"); /* method */ - put_bool(s->pktout, true); /* signature follows */ - put_stringz(s->pktout, s->publickey_algorithm); - pkblob = strbuf_new(); - ssh_key_public_blob(key->key, BinarySink_UPCAST(pkblob)); - put_string(s->pktout, pkblob->s, pkblob->len); - - /* - * The data to be signed is: - * - * string session-id - * - * followed by everything so far placed in the - * outgoing packet. - */ - sigdata = strbuf_new(); - ssh2_userauth_add_session_id(s, sigdata); - put_data(sigdata, s->pktout->data + 5, - s->pktout->length - 5); - sigblob = strbuf_new(); - ssh_key_sign(key->key, ptrlen_from_strbuf(sigdata), - s->signflags, BinarySink_UPCAST(sigblob)); - strbuf_free(sigdata); - ssh2_userauth_add_sigblob( - s, s->pktout, ptrlen_from_strbuf(pkblob), - ptrlen_from_strbuf(sigblob)); - strbuf_free(pkblob); - strbuf_free(sigblob); - - pq_push(s->ppl.out_pq, s->pktout); - ppl_logevent("Sent public key signature"); - s->type = AUTH_TYPE_PUBLICKEY; - ssh_key_free(key->key); - sfree(key->comment); - sfree(key); - s->is_trivial_auth = false; - } - -#ifndef NO_GSSAPI - } else if (s->can_gssapi && !s->tried_gssapi) { - - /* gssapi-with-mic authentication */ - - ptrlen data; - - s->type = AUTH_TYPE_GSSAPI; - s->tried_gssapi = true; - s->ppl.bpp->pls->actx = SSH2_PKTCTX_GSSAPI; - - if (s->shgss->lib->gsslogmsg) - ppl_logevent("%s", s->shgss->lib->gsslogmsg); - - /* Sending USERAUTH_REQUEST with "gssapi-with-mic" method */ - ppl_logevent("Trying gssapi-with-mic..."); - s->pktout = ssh_bpp_new_pktout( - s->ppl.bpp, SSH2_MSG_USERAUTH_REQUEST); - put_stringz(s->pktout, s->username); - put_stringz(s->pktout, s->successor_layer->vt->name); - put_stringz(s->pktout, "gssapi-with-mic"); - ppl_logevent("Attempting GSSAPI authentication"); - - /* add mechanism info */ - s->shgss->lib->indicate_mech(s->shgss->lib, &s->gss_buf); - - /* number of GSSAPI mechanisms */ - put_uint32(s->pktout, 1); - - /* length of OID + 2 */ - put_uint32(s->pktout, s->gss_buf.length + 2); - put_byte(s->pktout, SSH2_GSS_OIDTYPE); - - /* length of OID */ - put_byte(s->pktout, s->gss_buf.length); - - put_data(s->pktout, s->gss_buf.value, s->gss_buf.length); - pq_push(s->ppl.out_pq, s->pktout); - crMaybeWaitUntilV((pktin = ssh2_userauth_pop(s)) != NULL); - if (pktin->type != SSH2_MSG_USERAUTH_GSSAPI_RESPONSE) { - ppl_logevent("GSSAPI authentication request refused"); - pq_push_front(s->ppl.in_pq, pktin); - continue; - } - - /* check returned packet ... */ - - data = get_string(pktin); - s->gss_rcvtok.value = (char *)data.ptr; - s->gss_rcvtok.length = data.len; - if (s->gss_rcvtok.length != s->gss_buf.length + 2 || - ((char *)s->gss_rcvtok.value)[0] != SSH2_GSS_OIDTYPE || - ((char *)s->gss_rcvtok.value)[1] != s->gss_buf.length || - memcmp((char *)s->gss_rcvtok.value + 2, - s->gss_buf.value,s->gss_buf.length) ) { - ppl_logevent("GSSAPI authentication - wrong response " - "from server"); - continue; - } - - /* Import server name if not cached from KEX */ - if (s->shgss->srv_name == GSS_C_NO_NAME) { - s->gss_stat = s->shgss->lib->import_name( - s->shgss->lib, s->fullhostname, &s->shgss->srv_name); - if (s->gss_stat != SSH_GSS_OK) { - if (s->gss_stat == SSH_GSS_BAD_HOST_NAME) - ppl_logevent("GSSAPI import name failed -" - " Bad service name"); - else - ppl_logevent("GSSAPI import name failed"); - continue; - } - } - - /* Allocate our gss_ctx */ - s->gss_stat = s->shgss->lib->acquire_cred( - s->shgss->lib, &s->shgss->ctx, NULL); - if (s->gss_stat != SSH_GSS_OK) { - ppl_logevent("GSSAPI authentication failed to get " - "credentials"); - /* The failure was on our side, so the server - * won't be sending a response packet indicating - * failure. Avoid waiting for it next time round - * the loop. */ - s->suppress_wait_for_response_packet = true; - continue; - } - - /* initial tokens are empty */ - SSH_GSS_CLEAR_BUF(&s->gss_rcvtok); - SSH_GSS_CLEAR_BUF(&s->gss_sndtok); - - /* now enter the loop */ - do { - /* - * When acquire_cred yields no useful expiration, go with - * the service ticket expiration. - */ - s->gss_stat = s->shgss->lib->init_sec_context - (s->shgss->lib, - &s->shgss->ctx, - s->shgss->srv_name, - s->gssapi_fwd, - &s->gss_rcvtok, - &s->gss_sndtok, - NULL, - NULL); - - if (s->gss_stat!=SSH_GSS_S_COMPLETE && - s->gss_stat!=SSH_GSS_S_CONTINUE_NEEDED) { - ppl_logevent("GSSAPI authentication initialisation " - "failed"); - - if (s->shgss->lib->display_status(s->shgss->lib, - s->shgss->ctx, &s->gss_buf) == SSH_GSS_OK) { - ppl_logevent("%s", (char *)s->gss_buf.value); - sfree(s->gss_buf.value); - } - - pq_push_front(s->ppl.in_pq, pktin); - break; - } - ppl_logevent("GSSAPI authentication initialised"); - - /* - * Client and server now exchange tokens until GSSAPI - * no longer says CONTINUE_NEEDED - */ - if (s->gss_sndtok.length != 0) { - s->is_trivial_auth = false; - s->pktout = - ssh_bpp_new_pktout( - s->ppl.bpp, SSH2_MSG_USERAUTH_GSSAPI_TOKEN); - put_string(s->pktout, - s->gss_sndtok.value, s->gss_sndtok.length); - pq_push(s->ppl.out_pq, s->pktout); - s->shgss->lib->free_tok(s->shgss->lib, &s->gss_sndtok); - } - - if (s->gss_stat == SSH_GSS_S_CONTINUE_NEEDED) { - crMaybeWaitUntilV((pktin = ssh2_userauth_pop(s)) != NULL); - - if (pktin->type == SSH2_MSG_USERAUTH_GSSAPI_ERRTOK) { - /* - * Per RFC 4462 section 3.9, this packet - * type MUST immediately precede an - * ordinary USERAUTH_FAILURE. - * - * We currently don't know how to do - * anything with the GSSAPI error token - * contained in this packet, so we ignore - * it and just wait for the following - * FAILURE. - */ - crMaybeWaitUntilV( - (pktin = ssh2_userauth_pop(s)) != NULL); - if (pktin->type != SSH2_MSG_USERAUTH_FAILURE) { - ssh_proto_error( - s->ppl.ssh, "Received unexpected packet " - "after SSH_MSG_USERAUTH_GSSAPI_ERRTOK " - "(expected SSH_MSG_USERAUTH_FAILURE): " - "type %d (%s)", pktin->type, - ssh2_pkt_type(s->ppl.bpp->pls->kctx, - s->ppl.bpp->pls->actx, - pktin->type)); - return; - } - } - - if (pktin->type == SSH2_MSG_USERAUTH_FAILURE) { - ppl_logevent("GSSAPI authentication failed"); - s->gss_stat = SSH_GSS_FAILURE; - pq_push_front(s->ppl.in_pq, pktin); - break; - } else if (pktin->type != - SSH2_MSG_USERAUTH_GSSAPI_TOKEN) { - ppl_logevent("GSSAPI authentication -" - " bad server response"); - s->gss_stat = SSH_GSS_FAILURE; - break; - } - data = get_string(pktin); - s->gss_rcvtok.value = (char *)data.ptr; - s->gss_rcvtok.length = data.len; - } - } while (s-> gss_stat == SSH_GSS_S_CONTINUE_NEEDED); - - if (s->gss_stat != SSH_GSS_OK) { - s->shgss->lib->release_cred(s->shgss->lib, &s->shgss->ctx); - continue; - } - ppl_logevent("GSSAPI authentication loop finished OK"); - - /* Now send the MIC */ - - s->pktout = ssh2_userauth_gss_packet(s, "gssapi-with-mic"); - pq_push(s->ppl.out_pq, s->pktout); - - s->shgss->lib->release_cred(s->shgss->lib, &s->shgss->ctx); - continue; -#endif - } else if (s->can_keyb_inter && !s->kbd_inter_refused) { - - /* - * Keyboard-interactive authentication. - */ - - s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE; - - s->ppl.bpp->pls->actx = SSH2_PKTCTX_KBDINTER; - - s->pktout = ssh_bpp_new_pktout( - s->ppl.bpp, SSH2_MSG_USERAUTH_REQUEST); - put_stringz(s->pktout, s->username); - put_stringz(s->pktout, s->successor_layer->vt->name); - put_stringz(s->pktout, "keyboard-interactive"); - /* method */ - put_stringz(s->pktout, ""); /* lang */ - put_stringz(s->pktout, ""); /* submethods */ - pq_push(s->ppl.out_pq, s->pktout); - - ppl_logevent("Attempting keyboard-interactive authentication"); - - if (!s->ki_scc_initialised) { - s->ki_scc = seat_stripctrl_new( - s->ppl.seat, NULL, SIC_KI_PROMPTS); - if (s->ki_scc) - stripctrl_enable_line_limiting(s->ki_scc); - s->ki_scc_initialised = true; - } - - crMaybeWaitUntilV((pktin = ssh2_userauth_pop(s)) != NULL); - if (pktin->type != SSH2_MSG_USERAUTH_INFO_REQUEST) { - /* Server is not willing to do keyboard-interactive - * at all (or, bizarrely but legally, accepts the - * user without actually issuing any prompts). - * Give up on it entirely. */ - pq_push_front(s->ppl.in_pq, pktin); - s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET; - s->kbd_inter_refused = true; /* don't try it again */ - continue; - } - - s->ki_printed_header = false; - - /* - * Loop while the server continues to send INFO_REQUESTs. - */ - while (pktin->type == SSH2_MSG_USERAUTH_INFO_REQUEST) { - ptrlen name, inst; - strbuf *sb; - - /* - * We've got a fresh USERAUTH_INFO_REQUEST. - * Get the preamble and start building a prompt. - */ - name = get_string(pktin); - inst = get_string(pktin); - get_string(pktin); /* skip language tag */ - s->cur_prompt = new_prompts(); - s->cur_prompt->to_server = true; - s->cur_prompt->from_server = true; - - /* - * Get any prompt(s) from the packet. - */ - s->num_prompts = get_uint32(pktin); - for (uint32_t i = 0; i < s->num_prompts; i++) { - s->is_trivial_auth = false; - ptrlen prompt = get_string(pktin); - bool echo = get_bool(pktin); - - if (get_err(pktin)) { - ssh_proto_error( - s->ppl.ssh, "Server sent truncated " - "SSH_MSG_USERAUTH_INFO_REQUEST packet"); - return; - } - - sb = strbuf_new(); - if (!prompt.len) { - put_datapl(sb, PTRLEN_LITERAL( - "<server failed to send prompt>: ")); - } else if (s->ki_scc) { - stripctrl_retarget( - s->ki_scc, BinarySink_UPCAST(sb)); - put_datapl(s->ki_scc, prompt); - stripctrl_retarget(s->ki_scc, NULL); - } else { - put_datapl(sb, prompt); - } - add_prompt(s->cur_prompt, strbuf_to_str(sb), echo); - } - - /* - * Make the header strings. This includes the - * 'name' (optional dialog-box title) and - * 'instruction' from the server. - * - * First, display our disambiguating header line - * if this is the first time round the loop - - * _unless_ the server has sent a completely empty - * k-i packet with no prompts _or_ text, which - * apparently some do. In that situation there's - * no need to alert the user that the following - * text is server- supplied, because, well, _what_ - * text? - * - * We also only do this if we got a stripctrl, - * because if we didn't, that suggests this is all - * being done via dialog boxes anyway. - */ - if (!s->ki_printed_header && s->ki_scc && - (s->num_prompts || name.len || inst.len)) { - ssh2_userauth_antispoof_msg( - s, "Keyboard-interactive authentication " - "prompts from server:"); - s->ki_printed_header = true; - seat_set_trust_status(s->ppl.seat, false); - } - - sb = strbuf_new(); - if (name.len) { - if (s->ki_scc) { - stripctrl_retarget(s->ki_scc, - BinarySink_UPCAST(sb)); - put_datapl(s->ki_scc, name); - stripctrl_retarget(s->ki_scc, NULL); - } else { - put_datapl(sb, name); - } - s->cur_prompt->name_reqd = true; - } else { - put_datapl(sb, PTRLEN_LITERAL( - "SSH server authentication")); - s->cur_prompt->name_reqd = false; - } - s->cur_prompt->name = strbuf_to_str(sb); - - sb = strbuf_new(); - if (inst.len) { - if (s->ki_scc) { - stripctrl_retarget(s->ki_scc, - BinarySink_UPCAST(sb)); - put_datapl(s->ki_scc, inst); - stripctrl_retarget(s->ki_scc, NULL); - } else { - put_datapl(sb, inst); - } - s->cur_prompt->instr_reqd = true; - } else { - s->cur_prompt->instr_reqd = false; - } - if (sb->len) - s->cur_prompt->instruction = strbuf_to_str(sb); - else - strbuf_free(sb); - - /* - * Our prompts_t is fully constructed now. Get the - * user's response(s). - */ - s->userpass_ret = seat_get_userpass_input( - s->ppl.seat, s->cur_prompt, NULL); - while (1) { - while (s->userpass_ret < 0 && - bufchain_size(s->ppl.user_input) > 0) - s->userpass_ret = seat_get_userpass_input( - s->ppl.seat, s->cur_prompt, s->ppl.user_input); - - if (s->userpass_ret >= 0) - break; - - s->want_user_input = true; - crReturnV; - s->want_user_input = false; - } - if (!s->userpass_ret) { - /* - * Failed to get responses. Terminate. - */ - free_prompts(s->cur_prompt); - ssh_bpp_queue_disconnect( - s->ppl.bpp, "Unable to authenticate", - SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER); - ssh_user_close(s->ppl.ssh, "User aborted during " - "keyboard-interactive authentication"); - return; - } - - /* - * Send the response(s) to the server. - */ - s->pktout = ssh_bpp_new_pktout( - s->ppl.bpp, SSH2_MSG_USERAUTH_INFO_RESPONSE); - put_uint32(s->pktout, s->num_prompts); - for (uint32_t i = 0; i < s->num_prompts; i++) { - put_stringz(s->pktout, prompt_get_result_ref( - s->cur_prompt->prompts[i])); - } - s->pktout->minlen = 256; - pq_push(s->ppl.out_pq, s->pktout); - - /* - * Free the prompts structure from this iteration. - * If there's another, a new one will be allocated - * when we return to the top of this while loop. - */ - free_prompts(s->cur_prompt); - - /* - * Get the next packet in case it's another - * INFO_REQUEST. - */ - crMaybeWaitUntilV((pktin = ssh2_userauth_pop(s)) != NULL); - - } - - /* - * Print our trailer line, if we printed a header. - */ - if (s->ki_printed_header) { - seat_set_trust_status(s->ppl.seat, true); - ssh2_userauth_antispoof_msg( - s, "End of keyboard-interactive prompts from server"); - } - - /* - * We should have SUCCESS or FAILURE now. - */ - pq_push_front(s->ppl.in_pq, pktin); - - } else if (s->can_passwd) { - s->is_trivial_auth = false; - /* - * Plain old password authentication. - */ - bool changereq_first_time; /* not live over crReturn */ - - s->ppl.bpp->pls->actx = SSH2_PKTCTX_PASSWORD; - - s->cur_prompt = new_prompts(); - s->cur_prompt->to_server = true; - s->cur_prompt->from_server = false; - s->cur_prompt->name = dupstr("SSH password"); - add_prompt(s->cur_prompt, dupprintf("%s@%s's password: ", - s->username, s->hostname), - false); - - s->userpass_ret = seat_get_userpass_input( - s->ppl.seat, s->cur_prompt, NULL); - while (1) { - while (s->userpass_ret < 0 && - bufchain_size(s->ppl.user_input) > 0) - s->userpass_ret = seat_get_userpass_input( - s->ppl.seat, s->cur_prompt, s->ppl.user_input); - - if (s->userpass_ret >= 0) - break; - - s->want_user_input = true; - crReturnV; - s->want_user_input = false; - } - if (!s->userpass_ret) { - /* - * Failed to get responses. Terminate. - */ - free_prompts(s->cur_prompt); - ssh_bpp_queue_disconnect( - s->ppl.bpp, "Unable to authenticate", - SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER); - ssh_user_close(s->ppl.ssh, "User aborted during password " - "authentication"); - return; - } - /* - * Squirrel away the password. (We may need it later if - * asked to change it.) - */ - s->password = prompt_get_result(s->cur_prompt->prompts[0]); - free_prompts(s->cur_prompt); - - /* - * Send the password packet. - * - * We pad out the password packet to 256 bytes to make - * it harder for an attacker to find the length of the - * user's password. - * - * Anyone using a password longer than 256 bytes - * probably doesn't have much to worry about from - * people who find out how long their password is! - */ - s->pktout = ssh_bpp_new_pktout( - s->ppl.bpp, SSH2_MSG_USERAUTH_REQUEST); - put_stringz(s->pktout, s->username); - put_stringz(s->pktout, s->successor_layer->vt->name); - put_stringz(s->pktout, "password"); - put_bool(s->pktout, false); - put_stringz(s->pktout, s->password); - s->pktout->minlen = 256; - pq_push(s->ppl.out_pq, s->pktout); - ppl_logevent("Sent password"); - s->type = AUTH_TYPE_PASSWORD; - - /* - * Wait for next packet, in case it's a password change - * request. - */ - crMaybeWaitUntilV((pktin = ssh2_userauth_pop(s)) != NULL); - changereq_first_time = true; - - while (pktin->type == SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ) { - - /* - * We're being asked for a new password - * (perhaps not for the first time). - * Loop until the server accepts it. - */ - - bool got_new = false; /* not live over crReturn */ - ptrlen prompt; /* not live over crReturn */ - - { - const char *msg; - if (changereq_first_time) - msg = "Server requested password change"; - else - msg = "Server rejected new password"; - ppl_logevent("%s", msg); - ppl_printf("%s\r\n", msg); - } - - prompt = get_string(pktin); - - s->cur_prompt = new_prompts(); - s->cur_prompt->to_server = true; - s->cur_prompt->from_server = false; - s->cur_prompt->name = dupstr("New SSH password"); - s->cur_prompt->instruction = mkstr(prompt); - s->cur_prompt->instr_reqd = true; - /* - * There's no explicit requirement in the protocol - * for the "old" passwords in the original and - * password-change messages to be the same, and - * apparently some Cisco kit supports password change - * by the user entering a blank password originally - * and the real password subsequently, so, - * reluctantly, we prompt for the old password again. - * - * (On the other hand, some servers don't even bother - * to check this field.) - */ - add_prompt(s->cur_prompt, - dupstr("Current password (blank for previously entered password): "), - false); - add_prompt(s->cur_prompt, dupstr("Enter new password: "), - false); - add_prompt(s->cur_prompt, dupstr("Confirm new password: "), - false); - - /* - * Loop until the user manages to enter the same - * password twice. - */ - while (!got_new) { - s->userpass_ret = seat_get_userpass_input( - s->ppl.seat, s->cur_prompt, NULL); - while (1) { - while (s->userpass_ret < 0 && - bufchain_size(s->ppl.user_input) > 0) - s->userpass_ret = seat_get_userpass_input( - s->ppl.seat, s->cur_prompt, - s->ppl.user_input); - - if (s->userpass_ret >= 0) - break; - - s->want_user_input = true; - crReturnV; - s->want_user_input = false; - } - if (!s->userpass_ret) { - /* - * Failed to get responses. Terminate. - */ - /* burn the evidence */ - free_prompts(s->cur_prompt); - smemclr(s->password, strlen(s->password)); - sfree(s->password); - ssh_bpp_queue_disconnect( - s->ppl.bpp, "Unable to authenticate", - SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER); - ssh_user_close(s->ppl.ssh, "User aborted during " - "password changing"); - return; - } - - /* - * If the user specified a new original password - * (IYSWIM), overwrite any previously specified - * one. - * (A side effect is that the user doesn't have to - * re-enter it if they louse up the new password.) - */ - if (s->cur_prompt->prompts[0]->result->s[0]) { - smemclr(s->password, strlen(s->password)); - /* burn the evidence */ - sfree(s->password); - s->password = prompt_get_result( - s->cur_prompt->prompts[0]); - } - - /* - * Check the two new passwords match. - */ - got_new = !strcmp( - prompt_get_result_ref(s->cur_prompt->prompts[1]), - prompt_get_result_ref(s->cur_prompt->prompts[2])); - if (!got_new) - /* They don't. Silly user. */ - ppl_printf("Passwords do not match\r\n"); - - } - - /* - * Send the new password (along with the old one). - * (see above for padding rationale) - */ - s->pktout = ssh_bpp_new_pktout( - s->ppl.bpp, SSH2_MSG_USERAUTH_REQUEST); - put_stringz(s->pktout, s->username); - put_stringz(s->pktout, s->successor_layer->vt->name); - put_stringz(s->pktout, "password"); - put_bool(s->pktout, true); - put_stringz(s->pktout, s->password); - put_stringz(s->pktout, prompt_get_result_ref( - s->cur_prompt->prompts[1])); - free_prompts(s->cur_prompt); - s->pktout->minlen = 256; - pq_push(s->ppl.out_pq, s->pktout); - ppl_logevent("Sent new password"); - - /* - * Now see what the server has to say about it. - * (If it's CHANGEREQ again, it's not happy with the - * new password.) - */ - crMaybeWaitUntilV((pktin = ssh2_userauth_pop(s)) != NULL); - changereq_first_time = false; - - } - - /* - * We need to reexamine the current pktin at the top - * of the loop. Either: - * - we weren't asked to change password at all, in - * which case it's a SUCCESS or FAILURE with the - * usual meaning - * - we sent a new password, and the server was - * either OK with it (SUCCESS or FAILURE w/partial - * success) or unhappy with the _old_ password - * (FAILURE w/o partial success) - * In any of these cases, we go back to the top of - * the loop and start again. - */ - pq_push_front(s->ppl.in_pq, pktin); - - /* - * We don't need the old password any more, in any - * case. Burn the evidence. - */ - smemclr(s->password, strlen(s->password)); - sfree(s->password); - - } else { - ssh_bpp_queue_disconnect( - s->ppl.bpp, - "No supported authentication methods available", - SSH2_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE); - ssh_sw_abort(s->ppl.ssh, "No supported authentication methods " - "available (server sent: %s)", - s->last_methods_string->s); - return; - } - - } - try_new_username:; - } - - userauth_success: - if (s->notrivialauth && s->is_trivial_auth) { - ssh_proto_error(s->ppl.ssh, "Authentication was trivial! " - "Abandoning session as specified in configuration."); - return; - } - - /* - * We've just received USERAUTH_SUCCESS, and we haven't sent - * any packets since. Signal the transport layer to consider - * doing an immediate rekey, if it has any reason to want to. - */ - ssh2_transport_notify_auth_done(s->transport_layer); - - /* - * Finally, hand over to our successor layer, and return - * immediately without reaching the crFinishV: ssh_ppl_replace - * will have freed us, so crFinishV's zeroing-out of crState would - * be a use-after-free bug. - */ - { - PacketProtocolLayer *successor = s->successor_layer; - s->successor_layer = NULL; /* avoid freeing it ourself */ - ssh_ppl_replace(&s->ppl, successor); - return; /* we've just freed s, so avoid even touching s->crState */ - } - - crFinishV; -} - -static void ssh2_userauth_add_session_id( - struct ssh2_userauth_state *s, strbuf *sigdata) -{ - if (s->ppl.remote_bugs & BUG_SSH2_PK_SESSIONID) { - put_datapl(sigdata, s->session_id); - } else { - put_stringpl(sigdata, s->session_id); - } -} - -static void ssh2_userauth_agent_query( - struct ssh2_userauth_state *s, strbuf *req) -{ - void *response; - int response_len; - - sfree(s->agent_response_to_free); - s->agent_response_to_free = NULL; - - s->auth_agent_query = agent_query(req, &response, &response_len, - ssh2_userauth_agent_callback, s); - if (!s->auth_agent_query) - ssh2_userauth_agent_callback(s, response, response_len); -} - -static void ssh2_userauth_agent_callback(void *uav, void *reply, int replylen) -{ - struct ssh2_userauth_state *s = (struct ssh2_userauth_state *)uav; - - s->auth_agent_query = NULL; - s->agent_response_to_free = reply; - s->agent_response = make_ptrlen(reply, replylen); - - queue_idempotent_callback(&s->ppl.ic_process_queue); -} - -/* - * Helper function to add an SSH-2 signature blob to a packet. Expects - * to be shown the public key blob as well as the signature blob. - * Normally just appends the sig blob unmodified as a string, except - * that it optionally breaks it open and fiddle with it to work around - * BUG_SSH2_RSA_PADDING. - */ -static void ssh2_userauth_add_sigblob( - struct ssh2_userauth_state *s, PktOut *pkt, ptrlen pkblob, ptrlen sigblob) -{ - BinarySource pk[1], sig[1]; - BinarySource_BARE_INIT_PL(pk, pkblob); - BinarySource_BARE_INIT_PL(sig, sigblob); - - /* dmemdump(pkblob, pkblob_len); */ - /* dmemdump(sigblob, sigblob_len); */ - - /* - * See if this is in fact an ssh-rsa signature and a buggy - * server; otherwise we can just do this the easy way. - */ - if ((s->ppl.remote_bugs & BUG_SSH2_RSA_PADDING) && - ptrlen_eq_string(get_string(pk), "ssh-rsa") && - ptrlen_eq_string(get_string(sig), "ssh-rsa")) { - ptrlen mod_mp, sig_mp; - size_t sig_prefix_len; - - /* - * Find the modulus and signature integers. - */ - get_string(pk); /* skip over exponent */ - mod_mp = get_string(pk); /* remember modulus */ - sig_prefix_len = sig->pos; - sig_mp = get_string(sig); - if (get_err(pk) || get_err(sig)) - goto give_up; - - /* - * Find the byte length of the modulus, not counting leading - * zeroes. - */ - while (mod_mp.len > 0 && *(const char *)mod_mp.ptr == 0) { - mod_mp.len--; - mod_mp.ptr = (const char *)mod_mp.ptr + 1; - } - - /* debug("modulus length is %d\n", len); */ - /* debug("signature length is %d\n", siglen); */ - - if (mod_mp.len > sig_mp.len) { - strbuf *substr = strbuf_new(); - put_data(substr, sigblob.ptr, sig_prefix_len); - put_uint32(substr, mod_mp.len); - put_padding(substr, mod_mp.len - sig_mp.len, 0); - put_datapl(substr, sig_mp); - put_stringsb(pkt, substr); - return; - } - - /* Otherwise fall through and do it the easy way. We also come - * here as a fallback if we discover above that the key blob - * is misformatted in some way. */ - give_up:; - } - - put_stringpl(pkt, sigblob); -} - -#ifndef NO_GSSAPI -static PktOut *ssh2_userauth_gss_packet( - struct ssh2_userauth_state *s, const char *authtype) -{ - strbuf *sb; - PktOut *p; - Ssh_gss_buf buf; - Ssh_gss_buf mic; - - /* - * The mic is computed over the session id + intended - * USERAUTH_REQUEST packet. - */ - sb = strbuf_new(); - put_stringpl(sb, s->session_id); - put_byte(sb, SSH2_MSG_USERAUTH_REQUEST); - put_stringz(sb, s->username); - put_stringz(sb, s->successor_layer->vt->name); - put_stringz(sb, authtype); - - /* Compute the mic */ - buf.value = sb->s; - buf.length = sb->len; - s->shgss->lib->get_mic(s->shgss->lib, s->shgss->ctx, &buf, &mic); - strbuf_free(sb); - - /* Now we can build the real packet */ - if (strcmp(authtype, "gssapi-with-mic") == 0) { - p = ssh_bpp_new_pktout(s->ppl.bpp, SSH2_MSG_USERAUTH_GSSAPI_MIC); - } else { - p = ssh_bpp_new_pktout(s->ppl.bpp, SSH2_MSG_USERAUTH_REQUEST); - put_stringz(p, s->username); - put_stringz(p, s->successor_layer->vt->name); - put_stringz(p, authtype); - } - put_string(p, mic.value, mic.length); - - return p; -} -#endif - -static bool ssh2_userauth_get_specials( - PacketProtocolLayer *ppl, add_special_fn_t add_special, void *ctx) -{ - /* No specials provided by this layer. */ - return false; -} - -static void ssh2_userauth_special_cmd(PacketProtocolLayer *ppl, - SessionSpecialCode code, int arg) -{ - /* No specials provided by this layer. */ -} - -static bool ssh2_userauth_want_user_input(PacketProtocolLayer *ppl) -{ - struct ssh2_userauth_state *s = - container_of(ppl, struct ssh2_userauth_state, ppl); - return s->want_user_input; -} - -static void ssh2_userauth_got_user_input(PacketProtocolLayer *ppl) -{ - struct ssh2_userauth_state *s = - container_of(ppl, struct ssh2_userauth_state, ppl); - if (s->want_user_input) - queue_idempotent_callback(&s->ppl.ic_process_queue); -} - -static void ssh2_userauth_reconfigure(PacketProtocolLayer *ppl, Conf *conf) -{ - struct ssh2_userauth_state *s = - container_of(ppl, struct ssh2_userauth_state, ppl); - ssh_ppl_reconfigure(s->successor_layer, conf); -} - -static void ssh2_userauth_antispoof_msg( - struct ssh2_userauth_state *s, const char *msg) -{ - strbuf *sb = strbuf_new(); - if (seat_set_trust_status(s->ppl.seat, true)) { - /* - * If the seat can directly indicate that this message is - * generated by the client, then we can just use the message - * unmodified as an unspoofable header. - */ - put_datapl(sb, ptrlen_from_asciz(msg)); - } else { - /* - * Otherwise, add enough padding around it that the server - * wouldn't be able to mimic it within our line-length - * constraint. - */ - strbuf_catf(sb, "-- %s ", msg); - while (sb->len < 78) - put_byte(sb, '-'); - } - put_datapl(sb, PTRLEN_LITERAL("\r\n")); - seat_stderr_pl(s->ppl.seat, ptrlen_from_strbuf(sb)); - strbuf_free(sb); -} |