X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/231ee168f3732ad79bdc8772ab91393f109b8f53..5a71c4ea7cbe7888e3dc79cea7b06cf56b0fecb5:/ssh.c diff --git a/ssh.c b/ssh.c index d9981ed1..1885088f 100644 --- a/ssh.c +++ b/ssh.c @@ -181,6 +181,7 @@ static const char *const ssh2_disconnect_reasons[] = { #define BUG_SSH2_HMAC 2 #define BUG_NEEDS_SSH1_PLAIN_PASSWORD 4 #define BUG_CHOKES_ON_RSA 8 +#define BUG_SSH2_RSA_PADDING 16 static int ssh_pkt_ctx = 0; @@ -514,8 +515,6 @@ static const struct ssh_compress *sccomp = NULL; static const struct ssh_kex *kex = NULL; static const struct ssh_signkey *hostkey = NULL; static unsigned char ssh2_session_id[20]; -int (*ssh_get_line) (const char *prompt, char *str, int maxlen, - int is_pw) = NULL; static char *savedhost; static int savedport; @@ -1540,6 +1539,7 @@ static int ssh2_pkt_getbool(void) static void ssh2_pkt_getstring(char **p, int *length) { *p = NULL; + *length = 0; if (pktin.length - pktin.savedpos < 4) return; *length = GET_32BIT(pktin.data + pktin.savedpos); @@ -1567,6 +1567,75 @@ static Bignum ssh2_pkt_getmp(void) } /* + * Helper function to add an SSH2 signature blob to a packet. + * Expects to be shown the public key blob as well as the signature + * blob. Normally works just like ssh2_pkt_addstring, but will + * fiddle with the signature packet if necessary for + * BUG_SSH2_RSA_PADDING. + */ +static void ssh2_add_sigblob(void *pkblob_v, int pkblob_len, + void *sigblob_v, int sigblob_len) +{ + unsigned char *pkblob = (unsigned char *)pkblob_v; + unsigned char *sigblob = (unsigned char *)sigblob_v; + + /* 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 ((ssh_remote_bugs & BUG_SSH2_RSA_PADDING) && + (GET_32BIT(pkblob) == 7 && !memcmp(pkblob+4, "ssh-rsa", 7))) { + int pos, len, siglen; + + /* + * Find the byte length of the modulus. + */ + + pos = 4+7; /* skip over "ssh-rsa" */ + pos += 4 + GET_32BIT(pkblob+pos); /* skip over exponent */ + len = GET_32BIT(pkblob+pos); /* find length of modulus */ + pos += 4; /* find modulus itself */ + while (len > 0 && pkblob[pos] == 0) + len--, pos++; + /* debug(("modulus length is %d\n", len)); */ + + /* + * Now find the signature integer. + */ + pos = 4+7; /* skip over "ssh-rsa" */ + siglen = GET_32BIT(sigblob+pos); + /* debug(("signature length is %d\n", siglen)); */ + + if (len != siglen) { + unsigned char newlen[4]; + ssh2_pkt_addstring_start(); + ssh2_pkt_addstring_data(sigblob, pos); + /* dmemdump(sigblob, pos); */ + pos += 4; /* point to start of actual sig */ + PUT_32BIT(newlen, len); + ssh2_pkt_addstring_data(newlen, 4); + /* dmemdump(newlen, 4); */ + newlen[0] = 0; + while (len-- > siglen) { + ssh2_pkt_addstring_data(newlen, 1); + /* dmemdump(newlen, 1); */ + } + ssh2_pkt_addstring_data(sigblob+pos, siglen); + /* dmemdump(sigblob+pos, siglen); */ + return; + } + + /* Otherwise fall through and do it the easy way. */ + } + + ssh2_pkt_addstring_start(); + ssh2_pkt_addstring_data(sigblob, sigblob_len); +} + +/* * Examine the remote side's version string and compare it against * a list of known buggy implementations. */ @@ -1622,6 +1691,15 @@ static void ssh_detect_bugs(char *vstring) ssh_remote_bugs |= BUG_SSH2_HMAC; logevent("We believe remote version has SSH2 HMAC bug"); } + + if ((!strncmp(imp, "OpenSSH_2.", 10) && imp[10]>='5' && imp[10]<='9') || + (!strncmp(imp, "OpenSSH_3.", 10) && imp[10]>='0' && imp[10]<='2')) { + /* + * These versions have the SSH2 RSA padding bug. + */ + ssh_remote_bugs |= BUG_SSH2_RSA_PADDING; + logevent("We believe remote version has SSH2 RSA padding bug"); + } } static int do_ssh_init(unsigned char c) @@ -1722,6 +1800,12 @@ static int do_ssh_init(unsigned char c) sprintf(vlog, "We claim version: %s", verstring); logevent(vlog); strcat(verstring, "\n"); + + if (cfg.sshprot == 3) { + bombout(("SSH protocol version 2 required by user but not provided by server")); + crReturn(0); + } + logevent("Using SSH protocol version 1"); sk_write(s, verstring, strlen(verstring)); ssh_protocol = ssh1_protocol; @@ -2142,7 +2226,7 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) static int pos = 0; static char c; if ((flags & FLAG_INTERACTIVE) && !*cfg.username) { - if (ssh_get_line) { + if (ssh_get_line && !ssh_getline_pw_only) { if (!ssh_get_line("login as: ", username, sizeof(username), FALSE)) { /* @@ -2733,7 +2817,7 @@ void sshfwd_close(struct ssh_channel *c) * on it now, and then when the server acks the channel * open, we can close it then. */ - if (c->remoteid != -1) { + if (((int)c->remoteid) != -1) { if (ssh_version == 1) { send_packet(SSH1_MSG_CHANNEL_CLOSE, PKT_INT, c->remoteid, PKT_END); @@ -3949,7 +4033,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) static int tried_pubkey_config, tried_agent, tried_keyb_inter; static int kbd_inter_running; static int we_are_in; - static int num_prompts, echo; + static int num_prompts, curr_prompt, echo; static char username[100]; static int got_username; static char pwprompt[200]; @@ -4012,7 +4096,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) * it again. */ } else if ((flags & FLAG_INTERACTIVE) && !*cfg.username) { - if (ssh_get_line) { + if (ssh_get_line && !ssh_getline_pw_only) { if (!ssh_get_line("login as: ", username, sizeof(username), FALSE)) { /* @@ -4150,9 +4234,14 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) if (kbd_inter_running && pktin.type == SSH2_MSG_USERAUTH_INFO_REQUEST) { /* - * This is a further prompt in keyboard-interactive - * authentication. Do nothing. + * This is either a further set-of-prompts packet + * in keyboard-interactive authentication, or it's + * the same one and we came back here with `gotit' + * set. In the former case, we must reset the + * curr_prompt variable. */ + if (!gotit) + curr_prompt = 0; } else if (pktin.type != SSH2_MSG_USERAUTH_FAILURE) { bombout(("Strange packet received during authentication: type %d", pktin.type)); @@ -4236,6 +4325,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) static int authed = FALSE; void *r; + ssh_pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK; ssh_pkt_ctx |= SSH2_PKTCTX_PUBLICKEY; tried_agent = TRUE; @@ -4353,10 +4443,8 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) if (ret) { if (ret[4] == SSH2_AGENT_SIGN_RESPONSE) { logevent("Sending Pageant's response"); - ssh2_pkt_addstring_start(); - ssh2_pkt_addstring_data(ret + 9, - GET_32BIT(ret + - 5)); + ssh2_add_sigblob(pkblob, pklen, + ret + 9, GET_32BIT(ret + 5)); ssh2_pkt_send(); authed = TRUE; break; @@ -4380,6 +4468,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) tried_pubkey_config = TRUE; + ssh_pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK; ssh_pkt_ctx |= SSH2_PKTCTX_PUBLICKEY; /* @@ -4434,6 +4523,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) type = AUTH_TYPE_KEYBOARD_INTERACTIVE; tried_keyb_inter = TRUE; + ssh_pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK; ssh_pkt_ctx |= SSH2_PKTCTX_KBDINTER; ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST); @@ -4454,6 +4544,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) } kbd_inter_running = TRUE; + curr_prompt = 0; } if (kbd_inter_running) { @@ -4461,34 +4552,58 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) type = AUTH_TYPE_KEYBOARD_INTERACTIVE; tried_keyb_inter = TRUE; + ssh_pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK; ssh_pkt_ctx |= SSH2_PKTCTX_KBDINTER; - /* We've got packet with that "interactive" info - dump banners, and set its prompt as ours */ - { - char *name, *inst, *lang, *prompt; - int name_len, inst_len, lang_len, prompt_len; + if (curr_prompt == 0) { + /* + * We've got a fresh USERAUTH_INFO_REQUEST. + * Display header data, and start going through + * the prompts. + */ + char *name, *inst, *lang; + int name_len, inst_len, lang_len; + ssh2_pkt_getstring(&name, &name_len); ssh2_pkt_getstring(&inst, &inst_len); ssh2_pkt_getstring(&lang, &lang_len); - if (name_len > 0) + if (name_len > 0) { c_write_untrusted(name, name_len); - if (inst_len > 0) + c_write_str("\n"); + } + if (inst_len > 0) { c_write_untrusted(inst, inst_len); + c_write_str("\n"); + } num_prompts = ssh2_pkt_getuint32(); + } - ssh2_pkt_getstring(&prompt, &prompt_len); - strncpy(pwprompt, prompt, sizeof(pwprompt)); - pwprompt[prompt_len < sizeof(pwprompt) ? - prompt_len : sizeof(pwprompt)-1] = '\0'; - need_pw = TRUE; + /* + * If there are prompts remaining in the packet, + * display one and get a response. + */ + if (curr_prompt < num_prompts) { + char *prompt; + int prompt_len; + ssh2_pkt_getstring(&prompt, &prompt_len); + if (prompt_len > 0) { + strncpy(pwprompt, prompt, sizeof(pwprompt)); + pwprompt[prompt_len < sizeof(pwprompt) ? + prompt_len : sizeof(pwprompt)-1] = '\0'; + } else { + strcpy(pwprompt, + ": "); + } echo = ssh2_pkt_getbool(); - } + need_pw = TRUE; + } else + need_pw = FALSE; } if (!method && can_passwd) { method = AUTH_PASSWORD; + ssh_pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK; ssh_pkt_ctx |= SSH2_PKTCTX_PASSWORD; sprintf(pwprompt, "%.90s@%.90s's password: ", username, savedhost); @@ -4579,8 +4694,8 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) ssh2_pkt_send(); type = AUTH_TYPE_NONE; } else { - unsigned char *blob, *sigdata; - int blob_len, sigdata_len; + unsigned char *pkblob, *sigblob, *sigdata; + int pkblob_len, sigblob_len, sigdata_len; /* * We have loaded the private key and the server @@ -4593,10 +4708,9 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) ssh2_pkt_addstring("publickey"); /* method */ ssh2_pkt_addbool(TRUE); ssh2_pkt_addstring(key->alg->name); - blob = key->alg->public_blob(key->data, &blob_len); + pkblob = key->alg->public_blob(key->data, &pkblob_len); ssh2_pkt_addstring_start(); - ssh2_pkt_addstring_data(blob, blob_len); - sfree(blob); + ssh2_pkt_addstring_data(pkblob, pkblob_len); /* * The data to be signed is: @@ -4612,12 +4726,12 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) memcpy(sigdata + 4, ssh2_session_id, 20); memcpy(sigdata + 24, pktout.data + 5, pktout.length - 5); - blob = - key->alg->sign(key->data, sigdata, sigdata_len, - &blob_len); - ssh2_pkt_addstring_start(); - ssh2_pkt_addstring_data(blob, blob_len); - sfree(blob); + sigblob = key->alg->sign(key->data, sigdata, + sigdata_len, &sigblob_len); + ssh2_add_sigblob(pkblob, pkblob_len, + sigblob, sigblob_len); + sfree(pkblob); + sfree(sigblob); sfree(sigdata); ssh2_pkt_send(); @@ -4681,11 +4795,28 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) logevent("Sent password"); type = AUTH_TYPE_PASSWORD; } else if (method == AUTH_KEYBOARD_INTERACTIVE) { - ssh2_pkt_init(SSH2_MSG_USERAUTH_INFO_RESPONSE); - ssh2_pkt_adduint32(num_prompts); - ssh2_pkt_addstring(password); - memset(password, 0, sizeof(password)); - ssh2_pkt_send(); + if (curr_prompt == 0) { + ssh2_pkt_init(SSH2_MSG_USERAUTH_INFO_RESPONSE); + ssh2_pkt_adduint32(num_prompts); + } + if (need_pw) { /* only add pw if we just got one! */ + ssh2_pkt_addstring(password); + memset(password, 0, sizeof(password)); + curr_prompt++; + } + if (curr_prompt >= num_prompts) { + ssh2_pkt_send(); + } else { + /* + * If there are prompts remaining, we set + * `gotit' so that we won't attempt to get + * another packet. Then we go back round the + * loop and will end up retrieving another + * prompt out of the existing packet. Funky or + * what? + */ + gotit = TRUE; + } type = AUTH_TYPE_KEYBOARD_INTERACTIVE; } else { c_write_str @@ -5275,7 +5406,6 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) c->type = CHAN_SOCKDATA; c->v.v2.remwindow = ssh2_pkt_getuint32(); c->v.v2.remmaxpkt = ssh2_pkt_getuint32(); - bufchain_init(&c->v.v2.outbuffer); if (c->u.pfd.s) pfd_confirm(c->u.pfd.s); if (c->closes) { @@ -5677,6 +5807,7 @@ void *new_sock_channel(Socket s) c->closes = 0; c->type = CHAN_SOCKDATA_DORMANT;/* identify channel type */ c->u.pfd.s = s; + bufchain_init(&c->v.v2.outbuffer); add234(ssh_channels, c); } return c;