X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/b3186d641ae97703a794cc1e6e29eac80ad5781b..2184a5d91ffbcf2de2f730c83dda2d9443035f50:/ssh.c diff --git a/ssh.c b/ssh.c index c75c8fe9..2163e211 100644 --- a/ssh.c +++ b/ssh.c @@ -159,6 +159,8 @@ static const char *const ssh2_disconnect_reasons[] = { */ #define BUG_CHOKES_ON_SSH1_IGNORE 1 #define BUG_SSH2_HMAC 2 +#define BUG_NEEDS_SSH1_PLAIN_PASSWORD 4 + #define GET_32BIT(cp) \ (((unsigned long)(unsigned char)(cp)[0] << 24) | \ @@ -195,25 +197,52 @@ enum { PKT_END, PKT_INT, PKT_CHAR, PKT_DATA, PKT_STR, PKT_BIGNUM }; extern char *x11_init(Socket *, char *, void *); extern void x11_close(Socket); -extern void x11_send(Socket, char *, int); +extern int x11_send(Socket, char *, int); extern void x11_invent_auth(char *, int, char *, int); +extern void x11_unthrottle(Socket s); +extern void x11_override_throttle(Socket s, int enable); extern char *pfd_newconnect(Socket * s, char *hostname, int port, void *c); extern char *pfd_addforward(char *desthost, int destport, int port); extern void pfd_close(Socket s); -extern void pfd_send(Socket s, char *data, int len); +extern int pfd_send(Socket s, char *data, int len); extern void pfd_confirm(Socket s); +extern void pfd_unthrottle(Socket s); +extern void pfd_override_throttle(Socket s, int enable); + +/* + * Buffer management constants. There are several of these for + * various different purposes: + * + * - SSH1_BUFFER_LIMIT is the amount of backlog that must build up + * on a local data stream before we throttle the whole SSH + * connection (in SSH1 only). Throttling the whole connection is + * pretty drastic so we set this high in the hope it won't + * happen very often. + * + * - SSH_MAX_BACKLOG is the amount of backlog that must build up + * on the SSH connection itself before we defensively throttle + * _all_ local data streams. This is pretty drastic too (though + * thankfully unlikely in SSH2 since the window mechanism should + * ensure that the server never has any need to throttle its end + * of the connection), so we set this high as well. + * + * - OUR_V2_WINSIZE is the maximum window size we present on SSH2 + * channels. + */ + +#define SSH1_BUFFER_LIMIT 32768 +#define SSH_MAX_BACKLOG 32768 +#define OUR_V2_WINSIZE 16384 /* - * Ciphers for SSH2. We miss out single-DES because it isn't - * supported; also 3DES and Blowfish are both done differently from - * SSH1. (3DES uses outer chaining; Blowfish has the opposite - * endianness and different-sized keys.) + * Ciphers for SSH2. */ const static struct ssh2_ciphers *ciphers[] = { &ssh2_aes, &ssh2_blowfish, &ssh2_3des, + &ssh2_des, }; const static struct ssh_kex *kex_algs[] = { @@ -282,11 +311,16 @@ struct ssh_channel { unsigned remoteid, localid; int type; int closes; - struct ssh2_data_channel { - unsigned char *outbuffer; - unsigned outbuflen, outbufsize; - unsigned remwindow, remmaxpkt; - } v2; + union { + struct ssh1_data_channel { + int throttling; + } v1; + struct ssh2_data_channel { + bufchain outbuffer; + unsigned remwindow, remmaxpkt; + unsigned locwindow; + } v2; + } v; union { struct ssh_agent_channel { unsigned char *message; @@ -394,17 +428,30 @@ static struct Packet pktout = { 0, 0, NULL, NULL, 0 }; static unsigned char *deferred_send_data = NULL; static int deferred_len = 0, deferred_size = 0; +/* + * Gross hack: pscp will try to start SFTP but fall back to scp1 if + * that fails. This variable is the means by which scp.c can reach + * into the SSH code and find out which one it got. + */ +int ssh_fallback_cmd = 0; + static int ssh_version; +static int ssh1_throttle_count; +static int ssh_overall_bufsize; +static int ssh_throttled_all; +static int ssh1_stdout_throttling; static void (*ssh_protocol) (unsigned char *in, int inlen, int ispkt); static void ssh1_protocol(unsigned char *in, int inlen, int ispkt); static void ssh2_protocol(unsigned char *in, int inlen, int ispkt); static void ssh_size(void); static void ssh_special(Telnet_Special); -static void ssh2_try_send(struct ssh_channel *c); +static int ssh2_try_send(struct ssh_channel *c); static void ssh2_add_channel_data(struct ssh_channel *c, char *buf, int len); - +static void ssh_throttle_all(int enable, int bufsize); +static void ssh2_set_window(struct ssh_channel *c, unsigned newwin); static int (*s_rdpkt) (unsigned char **data, int *datalen); +static int ssh_sendbuffer(void); static struct rdpkt1_state_tag { long len, pad, biglen, to_read; @@ -460,7 +507,7 @@ static int ssh_rportcmp_ssh2(void *av, void *bv) { struct ssh_rportfwd *a = (struct ssh_rportfwd *) av; struct ssh_rportfwd *b = (struct ssh_rportfwd *) bv; - int i; + if (a->sport > b->sport) return +1; if (a->sport < b->sport) @@ -560,12 +607,6 @@ static int ssh1_rdpkt(unsigned char **data, int *datalen) (*data)++, (*datalen)--; } -#ifdef FWHACK - if (st->len == 0x52656d6f) { /* "Remo"te server has closed ... */ - st->len = 0x300; /* big enough to carry to end */ - } -#endif - st->pad = 8 - (st->len % 8); st->biglen = st->len + st->pad; pktin.length = st->len - 5; @@ -678,6 +719,8 @@ static int ssh1_rdpkt(unsigned char **data, int *datalen) memcpy(buf + nowlen, pktin.body + 4, msglen); buf[nowlen + msglen] = '\0'; logevent(buf); + bombout(("Server sent disconnect message:\n\"%s\"", buf+nowlen)); + crReturn(0); } crFinish(0); @@ -721,11 +764,7 @@ static int ssh2_rdpkt(unsigned char **data, int *datalen) pktin.data[st->i] = *(*data)++; (*datalen)--; } -#ifdef FWHACK - if (!memcmp(pktin.data, "Remo", 4)) { /* "Remo"te server has closed ... */ - /* FIXME */ - } -#endif + if (sccipher) sccipher->decrypt(pktin.data, st->cipherblk); @@ -851,6 +890,12 @@ static int ssh2_rdpkt(unsigned char **data, int *datalen) memcpy(buf + nowlen, pktin.data + 14, msglen); buf[nowlen + msglen] = '\0'; logevent(buf); + bombout(("Server sent disconnect message\ntype %d (%s):\n\"%s\"", + reason, + (reason > 0 && reason < lenof(ssh2_disconnect_reasons)) ? + ssh2_disconnect_reasons[reason] : "unknown", + buf+nowlen)); + crReturn(0); } crFinish(0); @@ -895,23 +940,18 @@ static int s_wrpkt_prepare(void) pktout.body[-1] = pktout.type; -#ifdef DUMP_PACKETS - debug(("Packet payload pre-compression:\n")); - dmemdump(pktout.body - 1, pktout.length + 1); -#endif - if (ssh1_compressing) { unsigned char *compblk; int complen; +#ifdef DUMP_PACKETS + debug(("Packet payload pre-compression:\n")); + dmemdump(pktout.body - 1, pktout.length + 1); +#endif zlib_compress_block(pktout.body - 1, pktout.length + 1, &compblk, &complen); ssh1_pktout_size(complen - 1); memcpy(pktout.body - 1, compblk, complen); sfree(compblk); -#ifdef DUMP_PACKETS - debug(("Packet payload post-compression:\n")); - dmemdump(pktout.body - 1, pktout.length + 1); -#endif } len = pktout.length + 5; /* type and CRC */ @@ -936,9 +976,11 @@ static int s_wrpkt_prepare(void) static void s_wrpkt(void) { - int len; + int len, backlog; len = s_wrpkt_prepare(); - sk_write(s, pktout.data, len); + backlog = sk_write(s, pktout.data, len); + if (backlog > SSH_MAX_BACKLOG) + ssh_throttle_all(1, backlog); } static void s_wrpkt_defer(void) @@ -1192,13 +1234,15 @@ static int ssh2_pkt_construct(void) /* * Compress packet payload. */ -#ifdef DUMP_PACKETS - debug(("Pre-compression payload:\n")); - dmemdump(pktout.data + 5, pktout.length - 5); -#endif { unsigned char *newpayload; int newlen; +#ifdef DUMP_PACKETS + if (cscomp && cscomp != &ssh_comp_none) { + debug(("Pre-compression payload:\n")); + dmemdump(pktout.data + 5, pktout.length - 5); + } +#endif if (cscomp && cscomp->compress(pktout.data + 5, pktout.length - 5, &newpayload, &newlen)) { pktout.length = 5; @@ -1244,8 +1288,12 @@ static int ssh2_pkt_construct(void) */ static void ssh2_pkt_send(void) { - int len = ssh2_pkt_construct(); - sk_write(s, pktout.data, len); + int len; + int backlog; + len = ssh2_pkt_construct(); + backlog = sk_write(s, pktout.data, len); + if (backlog > SSH_MAX_BACKLOG) + ssh_throttle_all(1, backlog); } /* @@ -1276,10 +1324,13 @@ static void ssh2_pkt_defer(void) */ static void ssh_pkt_defersend(void) { - sk_write(s, deferred_send_data, deferred_len); + int backlog; + backlog = sk_write(s, deferred_send_data, deferred_len); deferred_len = deferred_size = 0; sfree(deferred_send_data); deferred_send_data = NULL; + if (backlog > SSH_MAX_BACKLOG) + ssh_throttle_all(1, backlog); } #if 0 @@ -1364,17 +1415,15 @@ static void ssh_detect_bugs(char *vstring) char *imp; /* pointer to implementation part */ imp = vstring; imp += strcspn(imp, "-"); - if (*imp) - imp++; + if (*imp) imp++; imp += strcspn(imp, "-"); - if (*imp) - imp++; + if (*imp) imp++; ssh_remote_bugs = 0; if (!strcmp(imp, "1.2.18") || !strcmp(imp, "1.2.19") || !strcmp(imp, "1.2.20") || !strcmp(imp, "1.2.21") || - !strcmp(imp, "1.2.22")) { + !strcmp(imp, "1.2.22") || !strcmp(imp, "Cisco-1.25")) { /* * These versions don't support SSH1_MSG_IGNORE, so we have * to use a different defence against password length @@ -1384,6 +1433,16 @@ static void ssh_detect_bugs(char *vstring) logevent("We believe remote version has SSH1 ignore bug"); } + if (!strcmp(imp, "Cisco-1.25")) { + /* + * These versions need a plain password sent; they can't + * handle having a null and a random length of data after + * the password. + */ + ssh_remote_bugs |= BUG_NEEDS_SSH1_PLAIN_PASSWORD; + logevent("We believe remote version needs a plain SSH1 password"); + } + if (!strncmp(imp, "2.1.0", 5) || !strncmp(imp, "2.0.", 4) || !strncmp(imp, "2.2.0", 5) || !strncmp(imp, "2.3.0", 5) || !strncmp(imp, "2.1 ", 4)) { @@ -1425,8 +1484,8 @@ static int do_ssh_init(unsigned char c) crReturn(1); /* get another character */ } - vstring = smalloc(16); vstrsize = 16; + vstring = smalloc(vstrsize); strcpy(vstring, "SSH-"); vslen = 4; i = 0; @@ -1452,10 +1511,10 @@ static int do_ssh_init(unsigned char c) vstring[vslen] = 0; vlog = smalloc(20 + vslen); + vstring[strcspn (vstring, "\r\n")] = '\0'; /* remove end-of-line chars */ sprintf(vlog, "Server version: %s", vstring); - ssh_detect_bugs(vstring); - vlog[strcspn(vlog, "\r\n")] = '\0'; logevent(vlog); + ssh_detect_bugs(vstring); sfree(vlog); /* @@ -1538,6 +1597,9 @@ static void ssh_gotdata(unsigned char *data, int datalen) while (1) { while (datalen > 0) { if (s_rdpkt(&data, &datalen) == 0) { + if (ssh_state == SSH_STATE_CLOSED) { + return; + } ssh_protocol(NULL, 0, 1); if (ssh_state == SSH_STATE_CLOSED) { return; @@ -1579,17 +1641,29 @@ static int ssh_receive(Plug plug, int urgent, char *data, int len) return 1; } +static void ssh_sent(Plug plug, int bufsize) +{ + /* + * If the send backlog on the SSH socket itself clears, we + * should unthrottle the whole world if it was throttled. + */ + if (bufsize < SSH_MAX_BACKLOG) + ssh_throttle_all(0, bufsize); +} + /* * Connect to specified host and port. * Returns an error message, or NULL on success. * Also places the canonical host name into `realhost'. It must be * freed by the caller. */ -static char *connect_to_host(char *host, int port, char **realhost) +static char *connect_to_host(char *host, int port, char **realhost, int nodelay) { static struct plug_function_table fn_table = { ssh_closing, - ssh_receive + ssh_receive, + ssh_sent, + NULL }, *fn_table_ptr = &fn_table; SockAddr addr; @@ -1618,6 +1692,11 @@ static char *connect_to_host(char *host, int port, char **realhost) /* * Try to find host. */ + { + char buf[200]; + sprintf(buf, "Looking up host \"%.170s\"", host); + logevent(buf); + } addr = sk_namelookup(host, realhost); if ((err = sk_addr_error(addr))) return err; @@ -1629,7 +1708,13 @@ static char *connect_to_host(char *host, int port, char **realhost) /* * Open socket. */ - s = sk_new(addr, port, 0, 1, &fn_table_ptr); + { + char buf[200], addrbuf[100]; + sk_getaddr(addr, addrbuf, 100); + sprintf(buf, "Connecting to %.100s port %d", addrbuf, port); + logevent(buf); + } + s = sk_new(addr, port, 0, 1, nodelay, &fn_table_ptr); if ((err = sk_socket_error(s))) return err; @@ -1647,6 +1732,56 @@ static char *connect_to_host(char *host, int port, char **realhost) } /* + * Throttle or unthrottle the SSH connection. + */ +static void ssh1_throttle(int adjust) +{ + int old_count = ssh1_throttle_count; + ssh1_throttle_count += adjust; + assert(ssh1_throttle_count >= 0); + if (ssh1_throttle_count && !old_count) { + sk_set_frozen(s, 1); + } else if (!ssh1_throttle_count && old_count) { + sk_set_frozen(s, 0); + } +} + +/* + * Throttle or unthrottle _all_ local data streams (for when sends + * on the SSH connection itself back up). + */ +static void ssh_throttle_all(int enable, int bufsize) +{ + int i; + struct ssh_channel *c; + + if (enable == ssh_throttled_all) + return; + ssh_throttled_all = enable; + ssh_overall_bufsize = bufsize; + if (!ssh_channels) + return; + for (i = 0; NULL != (c = index234(ssh_channels, i)); i++) { + switch (c->type) { + case CHAN_MAINSESSION: + /* + * This is treated separately, outside the switch. + */ + break; + case CHAN_X11: + x11_override_throttle(c->u.x11.s, enable); + break; + case CHAN_AGENT: + /* Agent channels require no buffer management. */ + break; + case CHAN_SOCKDATA: + pfd_override_throttle(c->u.x11.s, enable); + break; + } + } +} + +/* * Handle the key exchange and user authentication phases. */ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) @@ -1659,6 +1794,7 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) struct MD5Context md5c; static unsigned long supported_ciphers_mask, supported_auths_mask; static int tried_publickey; + static int tis_auth_refused, ccard_auth_refused; static unsigned char session_id[16]; static int cipher_type; static char username[100]; @@ -1751,31 +1887,45 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) logevent("Encrypted session key"); - switch (cfg.cipher) { - case CIPHER_BLOWFISH: - cipher_type = SSH_CIPHER_BLOWFISH; - break; - case CIPHER_DES: - cipher_type = SSH_CIPHER_DES; - break; - case CIPHER_3DES: - cipher_type = SSH_CIPHER_3DES; - break; - case CIPHER_AES: - c_write_str("AES not supported in SSH1, falling back to 3DES\r\n"); - cipher_type = SSH_CIPHER_3DES; - break; - } - if ((supported_ciphers_mask & (1 << cipher_type)) == 0) { - c_write_str - ("Selected cipher not supported, falling back to 3DES\r\n"); - cipher_type = SSH_CIPHER_3DES; - if ((supported_ciphers_mask & (1 << cipher_type)) == 0) { - bombout(("Server violates SSH 1 protocol by " - "not supporting 3DES encryption")); + { + int cipher_chosen = 0, warn = 0; + char *cipher_string = NULL; + for (i = 0; !cipher_chosen && i < CIPHER_MAX; i++) { + int next_cipher = cfg.ssh_cipherlist[i]; + if (next_cipher == CIPHER_WARN) { + /* If/when we choose a cipher, warn about it */ + warn = 1; + } else if (next_cipher == CIPHER_AES) { + /* XXX Probably don't need to mention this. */ + logevent("AES not supported in SSH1, skipping"); + } else { + switch (next_cipher) { + case CIPHER_3DES: cipher_type = SSH_CIPHER_3DES; + cipher_string = "3DES"; break; + case CIPHER_BLOWFISH: cipher_type = SSH_CIPHER_BLOWFISH; + cipher_string = "Blowfish"; break; + case CIPHER_DES: cipher_type = SSH_CIPHER_DES; + cipher_string = "single-DES"; break; + } + if (supported_ciphers_mask & (1 << cipher_type)) + cipher_chosen = 1; + } + } + if (!cipher_chosen) { + if ((supported_ciphers_mask & (1 << SSH_CIPHER_3DES)) == 0) + bombout(("Server violates SSH 1 protocol by not " + "supporting 3DES encryption")); + else + /* shouldn't happen */ + bombout(("No supported ciphers found")); crReturn(0); } + + /* Warn about chosen cipher if necessary. */ + if (warn) + askcipher(cipher_string, 0); } + switch (cipher_type) { case SSH_CIPHER_3DES: logevent("Using 3DES encryption"); @@ -1893,6 +2043,7 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) crWaitUntil(ispkt); tried_publickey = 0; + tis_auth_refused = ccard_auth_refused = 0; while (pktin.type == SSH1_SMSG_FAILURE) { static char password[100]; @@ -1900,12 +2051,8 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) static int pos; static char c; static int pwpkt_type; - /* - * Show password prompt, having first obtained it via a TIS - * or CryptoCard exchange if we're doing TIS or CryptoCard - * authentication. - */ pwpkt_type = SSH1_CMSG_AUTH_PASSWORD; + if (agent_exists()) { /* * Attempt RSA authentication using Pageant. @@ -2028,9 +2175,9 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) if (*cfg.keyfile && !tried_publickey) pwpkt_type = SSH1_CMSG_AUTH_RSA; - if (pktin.type == SSH1_SMSG_FAILURE && - cfg.try_tis_auth && - (supported_auths_mask & (1 << SSH1_AUTH_TIS))) { + if (cfg.try_tis_auth && + (supported_auths_mask & (1 << SSH1_AUTH_TIS)) && + !tis_auth_refused) { pwpkt_type = SSH1_CMSG_AUTH_TIS_RESPONSE; logevent("Requested TIS authentication"); send_packet(SSH1_CMSG_AUTH_TIS, PKT_END); @@ -2039,6 +2186,8 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) logevent("TIS authentication declined"); if (flags & FLAG_INTERACTIVE) c_write_str("TIS authentication refused.\r\n"); + tis_auth_refused = 1; + continue; } else { int challengelen = ((pktin.body[0] << 24) | (pktin.body[1] << 16) | @@ -2048,12 +2197,17 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) if (challengelen > sizeof(prompt) - 1) challengelen = sizeof(prompt) - 1; /* prevent overrun */ memcpy(prompt, pktin.body + 4, challengelen); - prompt[challengelen] = '\0'; + /* Prompt heuristic comes from OpenSSH */ + strncpy(prompt + challengelen, + memchr(prompt, '\n', challengelen) ? + "": "\r\nResponse: ", + (sizeof prompt) - challengelen); + prompt[(sizeof prompt) - 1] = '\0'; } } - if (pktin.type == SSH1_SMSG_FAILURE && - cfg.try_tis_auth && - (supported_auths_mask & (1 << SSH1_AUTH_CCARD))) { + if (cfg.try_tis_auth && + (supported_auths_mask & (1 << SSH1_AUTH_CCARD)) && + !ccard_auth_refused) { pwpkt_type = SSH1_CMSG_AUTH_CCARD_RESPONSE; logevent("Requested CryptoCard authentication"); send_packet(SSH1_CMSG_AUTH_CCARD, PKT_END); @@ -2061,6 +2215,8 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) if (pktin.type != SSH1_SMSG_AUTH_CCARD_CHALLENGE) { logevent("CryptoCard authentication declined"); c_write_str("CryptoCard authentication refused.\r\n"); + ccard_auth_refused = 1; + continue; } else { int challengelen = ((pktin.body[0] << 24) | (pktin.body[1] << 16) | @@ -2070,7 +2226,9 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) if (challengelen > sizeof(prompt) - 1) challengelen = sizeof(prompt) - 1; /* prevent overrun */ memcpy(prompt, pktin.body + 4, challengelen); - strncpy(prompt + challengelen, "\r\nResponse : ", + strncpy(prompt + challengelen, + memchr(prompt, '\n', challengelen) ? + "" : "\r\nResponse: ", sizeof(prompt) - challengelen); prompt[sizeof(prompt) - 1] = '\0'; } @@ -2092,6 +2250,11 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) sfree(comment); } + /* + * Show password prompt, having first obtained it via a TIS + * or CryptoCard exchange if we're doing TIS or CryptoCard + * authentication. + */ if (ssh_get_line) { if (!ssh_get_line(prompt, password, sizeof(password), TRUE)) { /* @@ -2107,7 +2270,9 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) crReturn(1); } } else { - c_write_str(prompt); + /* Prompt may have come from server. We've munged it a bit, so + * we know it to be zero-terminated at least once. */ + c_write_untrusted(prompt, strlen(prompt)); pos = 0; ssh_send_ok = 1; while (pos >= 0) { @@ -2156,7 +2321,7 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) tried_publickey = 1; i = loadrsakey(cfg.keyfile, &pubkey, password); if (i == 0) { - c_write_str("Couldn't load public key from "); + c_write_str("Couldn't load private key from "); c_write_str(cfg.keyfile); c_write_str(".\r\n"); continue; /* go and try password */ @@ -2245,26 +2410,17 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) * use of the fact that the password is interpreted * as a C string: so we can append a NUL, then some * random data. + * + * One server (a Cisco one) can deal with neither + * SSH1_MSG_IGNORE _nor_ a padded password string. + * For this server we are left with no defences + * against password length sniffing. */ - if (ssh_remote_bugs & BUG_CHOKES_ON_SSH1_IGNORE) { - char string[64]; - char *s; - int len; - - len = strlen(password); - if (len < sizeof(string)) { - s = string; - strcpy(string, password); - len++; /* cover the zero byte */ - while (len < sizeof(string)) { - string[len++] = (char) random_byte(); - } - } else { - s = password; - } - send_packet(pwpkt_type, PKT_INT, len, - PKT_DATA, s, len, PKT_END); - } else { + if (!(ssh_remote_bugs & BUG_CHOKES_ON_SSH1_IGNORE)) { + /* + * The server can deal with SSH1_MSG_IGNORE, so + * we can use the primary defence. + */ int bottom, top, pwlen, i; char *randomstr; @@ -2296,7 +2452,45 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) PKT_STR, randomstr, PKT_END); } } + logevent("Sending password with camouflage packets"); ssh_pkt_defersend(); + } + else if (!(ssh_remote_bugs & BUG_NEEDS_SSH1_PLAIN_PASSWORD)) { + /* + * The server can't deal with SSH1_MSG_IGNORE + * but can deal with padded passwords, so we + * can use the secondary defence. + */ + char string[64]; + char *s; + int len; + + len = strlen(password); + if (len < sizeof(string)) { + s = string; + strcpy(string, password); + len++; /* cover the zero byte */ + while (len < sizeof(string)) { + string[len++] = (char) random_byte(); + } + } else { + s = password; + } + logevent("Sending length-padded password"); + send_packet(pwpkt_type, PKT_INT, len, + PKT_DATA, s, len, PKT_END); + } else { + /* + * The server has _both_ + * BUG_CHOKES_ON_SSH1_IGNORE and + * BUG_NEEDS_SSH1_PLAIN_PASSWORD. There is + * therefore nothing we can do. + */ + int len; + len = strlen(password); + logevent("Sending unpadded password"); + send_packet(pwpkt_type, PKT_INT, len, + PKT_DATA, password, len, PKT_END); } } else { send_packet(pwpkt_type, PKT_STR, password, PKT_END); @@ -2327,34 +2521,64 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) void sshfwd_close(struct ssh_channel *c) { if (c && !c->closes) { - if (ssh_version == 1) { - send_packet(SSH1_MSG_CHANNEL_CLOSE, PKT_INT, c->remoteid, - PKT_END); - } else { - ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE); - ssh2_pkt_adduint32(c->remoteid); - ssh2_pkt_send(); + /* + * If the channel's remoteid is -1, we have sent + * CHANNEL_OPEN for this channel, but it hasn't even been + * acknowledged by the server. So we must set a close flag + * on it now, and then when the server acks the channel + * open, we can close it then. + */ + if (c->remoteid != -1) { + if (ssh_version == 1) { + send_packet(SSH1_MSG_CHANNEL_CLOSE, PKT_INT, c->remoteid, + PKT_END); + } else { + ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE); + ssh2_pkt_adduint32(c->remoteid); + ssh2_pkt_send(); + } } c->closes = 1; if (c->type == CHAN_X11) { c->u.x11.s = NULL; logevent("Forwarded X11 connection terminated"); - } else if (c->type == CHAN_SOCKDATA) { + } else if (c->type == CHAN_SOCKDATA || + c->type == CHAN_SOCKDATA_DORMANT) { c->u.pfd.s = NULL; logevent("Forwarded port closed"); } } } -void sshfwd_write(struct ssh_channel *c, char *buf, int len) +int sshfwd_write(struct ssh_channel *c, char *buf, int len) { if (ssh_version == 1) { send_packet(SSH1_MSG_CHANNEL_DATA, PKT_INT, c->remoteid, PKT_INT, len, PKT_DATA, buf, len, PKT_END); + /* + * In SSH1 we can return 0 here - implying that forwarded + * connections are never individually throttled - because + * the only circumstance that can cause throttling will be + * the whole SSH connection backing up, in which case + * _everything_ will be throttled as a whole. + */ + return 0; } else { ssh2_add_channel_data(c, buf, len); - ssh2_try_send(c); + return ssh2_try_send(c); + } +} + +void sshfwd_unthrottle(struct ssh_channel *c, int bufsize) +{ + if (ssh_version == 1) { + if (c->v.v1.throttling && bufsize < SSH1_BUFFER_LIMIT) { + c->v.v1.throttling = 0; + ssh1_throttle(-1); + } + } else { + ssh2_set_window(c, OUR_V2_WINSIZE - bufsize); } } @@ -2518,12 +2742,26 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) zlib_decompress_init(); } - if (*cfg.remote_cmd_ptr) - send_packet(SSH1_CMSG_EXEC_CMD, PKT_STR, cfg.remote_cmd_ptr, - PKT_END); - else - send_packet(SSH1_CMSG_EXEC_SHELL, PKT_END); - logevent("Started session"); + /* + * Start the shell or command. + * + * Special case: if the first-choice command is an SSH2 + * subsystem (hence not usable here) and the second choice + * exists, we fall straight back to that. + */ + { + char *cmd = cfg.remote_cmd_ptr; + + if (cfg.ssh_subsys && cfg.remote_cmd_ptr2) { + cmd = cfg.remote_cmd_ptr2; + ssh_fallback_cmd = TRUE; + } + if (*cmd) + send_packet(SSH1_CMSG_EXEC_CMD, PKT_STR, cmd, PKT_END); + else + send_packet(SSH1_CMSG_EXEC_SHELL, PKT_END); + logevent("Started session"); + } ssh_state = SSH_STATE_SESSION; if (size_needed) @@ -2531,7 +2769,7 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) if (eof_needed) ssh_special(TS_EOF); - ldisc_send(NULL, 0); /* cause ldisc to notice changes */ + ldisc_send(NULL, 0, 0); /* cause ldisc to notice changes */ ssh_send_ok = 1; ssh_channels = newtree234(ssh_channelcmp); while (1) { @@ -2540,8 +2778,13 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) if (pktin.type == SSH1_SMSG_STDOUT_DATA || pktin.type == SSH1_SMSG_STDERR_DATA) { long len = GET_32BIT(pktin.body); - from_backend(pktin.type == SSH1_SMSG_STDERR_DATA, - pktin.body + 4, len); + int bufsize = + from_backend(pktin.type == SSH1_SMSG_STDERR_DATA, + pktin.body + 4, len); + if (!ssh1_stdout_throttling && bufsize > SSH1_BUFFER_LIMIT) { + ssh1_stdout_throttling = 1; + ssh1_throttle(+1); + } } else if (pktin.type == SSH1_MSG_DISCONNECT) { ssh_state = SSH_STATE_CLOSED; logevent("Received disconnect request"); @@ -2572,6 +2815,7 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) c->remoteid = GET_32BIT(pktin.body); c->localid = alloc_channel_id(); c->closes = 0; + c->v.v1.throttling = 0; c->type = CHAN_X11; /* identify channel type */ add234(ssh_channels, c); send_packet(SSH1_MSG_CHANNEL_OPEN_CONFIRMATION, @@ -2594,6 +2838,7 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) c->remoteid = GET_32BIT(pktin.body); c->localid = alloc_channel_id(); c->closes = 0; + c->v.v1.throttling = 0; c->type = CHAN_AGENT; /* identify channel type */ c->u.a.lensofar = 0; add234(ssh_channels, c); @@ -2646,6 +2891,7 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) c->remoteid = GET_32BIT(pktin.body); c->localid = alloc_channel_id(); c->closes = 0; + c->v.v1.throttling = 0; c->type = CHAN_SOCKDATA; /* identify channel type */ add234(ssh_channels, c); send_packet(SSH1_MSG_CHANNEL_OPEN_CONFIRMATION, @@ -2664,9 +2910,34 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) if (c && c->type == CHAN_SOCKDATA_DORMANT) { c->remoteid = localid; c->type = CHAN_SOCKDATA; + c->v.v1.throttling = 0; pfd_confirm(c->u.pfd.s); } + if (c && c->closes) { + /* + * We have a pending close on this channel, + * which we decided on before the server acked + * the channel open. So now we know the + * remoteid, we can close it again. + */ + send_packet(SSH1_MSG_CHANNEL_CLOSE, PKT_INT, c->remoteid, + PKT_END); + } + + } else if (pktin.type == SSH1_MSG_CHANNEL_OPEN_FAILURE) { + unsigned int remoteid = GET_32BIT(pktin.body); + unsigned int localid = GET_32BIT(pktin.body+4); + struct ssh_channel *c; + + c = find234(ssh_channels, &remoteid, ssh_channelfind); + if (c && c->type == CHAN_SOCKDATA_DORMANT) { + logevent("Forwarded connection refused by server"); + pfd_close(c->u.pfd.s); + del234(ssh_channels, c); + sfree(c); + } + } else if (pktin.type == SSH1_MSG_CHANNEL_CLOSE || pktin.type == SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION) { /* Remote side closes a channel. */ @@ -2706,12 +2977,13 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) struct ssh_channel *c; c = find234(ssh_channels, &i, ssh_channelfind); if (c) { + int bufsize; switch (c->type) { case CHAN_X11: - x11_send(c->u.x11.s, p, len); + bufsize = x11_send(c->u.x11.s, p, len); break; case CHAN_SOCKDATA: - pfd_send(c->u.pfd.s, p, len); + bufsize = pfd_send(c->u.pfd.s, p, len); break; case CHAN_AGENT: /* Data for an agent message. Buffer it. */ @@ -2764,8 +3036,13 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) c->u.a.lensofar = 0; } } + bufsize = 0; /* agent channels never back up */ break; } + if (!c->v.v1.throttling && bufsize > SSH1_BUFFER_LIMIT) { + c->v.v1.throttling = 1; + ssh1_throttle(+1); + } } } else if (pktin.type == SSH1_SMSG_SUCCESS) { /* may be from EXEC_SHELL on some servers */ @@ -2774,6 +3051,15 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) * if no pty is available or in other odd cases. Ignore */ } else if (pktin.type == SSH1_SMSG_EXIT_STATUS) { send_packet(SSH1_CMSG_EXIT_CONFIRMATION, PKT_END); + /* + * In case `helpful' firewalls or proxies tack + * extra human-readable text on the end of the + * session which we might mistake for another + * encrypted packet, we close the session once + * we've sent EXIT_CONFIRMATION. + */ + ssh_state = SSH_STATE_CLOSED; + crReturnV; } else { bombout(("Strange packet received: type %d", pktin.type)); crReturnV; @@ -2847,7 +3133,7 @@ static void ssh2_mkkey(Bignum K, char *H, char *sessid, char chr, */ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt) { - static int i, j, len, nbits, pbits; + static int i, j, len, nbits, pbits, warn; static char *str; static Bignum p, g, e, f, K; static int kex_init_value, kex_reply_value; @@ -2864,7 +3150,8 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt) static void *hkey; /* actual host key */ static unsigned char exchange_hash[20]; static unsigned char keyspace[40]; - static const struct ssh2_ciphers *preferred_cipher; + static int n_preferred_ciphers; + static const struct ssh2_ciphers *preferred_ciphers[CIPHER_MAX]; static const struct ssh_compress *preferred_comp; static int first_kex; @@ -2873,21 +3160,41 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt) first_kex = 1; /* - * Set up the preferred cipher and compression. + * Set up the preferred ciphers. (NULL => warn below here) */ - if (cfg.cipher == CIPHER_BLOWFISH) { - preferred_cipher = &ssh2_blowfish; - } else if (cfg.cipher == CIPHER_DES) { - logevent("Single DES not supported in SSH2; using 3DES"); - preferred_cipher = &ssh2_3des; - } else if (cfg.cipher == CIPHER_3DES) { - preferred_cipher = &ssh2_3des; - } else if (cfg.cipher == CIPHER_AES) { - preferred_cipher = &ssh2_aes; - } else { - /* Shouldn't happen, but we do want to initialise to _something_. */ - preferred_cipher = &ssh2_3des; + n_preferred_ciphers = 0; + for (i = 0; i < CIPHER_MAX; i++) { + switch (cfg.ssh_cipherlist[i]) { + case CIPHER_BLOWFISH: + preferred_ciphers[n_preferred_ciphers] = &ssh2_blowfish; + n_preferred_ciphers++; + break; + case CIPHER_DES: + preferred_ciphers[n_preferred_ciphers] = &ssh2_des; + n_preferred_ciphers++; + break; + case CIPHER_3DES: + preferred_ciphers[n_preferred_ciphers] = &ssh2_3des; + n_preferred_ciphers++; + break; + case CIPHER_AES: + preferred_ciphers[n_preferred_ciphers] = &ssh2_aes; + n_preferred_ciphers++; + break; + case CIPHER_WARN: + /* Flag for later. Don't bother if it's the last in + * the list. */ + if (i < CIPHER_MAX - 1) { + preferred_ciphers[n_preferred_ciphers] = NULL; + n_preferred_ciphers++; + } + break; + } } + + /* + * Set up preferred compression. + */ if (cfg.compression) preferred_comp = &ssh_zlib; else @@ -2924,23 +3231,23 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt) } /* List client->server encryption algorithms. */ ssh2_pkt_addstring_start(); - for (i = 0; i < lenof(ciphers) + 1; i++) { - const struct ssh2_ciphers *c = - i == 0 ? preferred_cipher : ciphers[i - 1]; + for (i = 0; i < n_preferred_ciphers; i++) { + const struct ssh2_ciphers *c = preferred_ciphers[i]; + if (!c) continue; /* warning flag */ for (j = 0; j < c->nciphers; j++) { ssh2_pkt_addstring_str(c->list[j]->name); - if (i < lenof(ciphers) || j < c->nciphers - 1) + if (i < n_preferred_ciphers || j < c->nciphers - 1) ssh2_pkt_addstring_str(","); } } /* List server->client encryption algorithms. */ ssh2_pkt_addstring_start(); - for (i = 0; i < lenof(ciphers) + 1; i++) { - const struct ssh2_ciphers *c = - i == 0 ? preferred_cipher : ciphers[i - 1]; + for (i = 0; i < n_preferred_ciphers; i++) { + const struct ssh2_ciphers *c = preferred_ciphers[i]; + if (!c) continue; /* warning flag */ for (j = 0; j < c->nciphers; j++) { ssh2_pkt_addstring_str(c->list[j]->name); - if (i < lenof(ciphers) || j < c->nciphers - 1) + if (i < n_preferred_ciphers || j < c->nciphers - 1) ssh2_pkt_addstring_str(","); } } @@ -3026,31 +3333,55 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt) } } ssh2_pkt_getstring(&str, &len); /* client->server cipher */ - for (i = 0; i < lenof(ciphers) + 1; i++) { - const struct ssh2_ciphers *c = - i == 0 ? preferred_cipher : ciphers[i - 1]; - for (j = 0; j < c->nciphers; j++) { - if (in_commasep_string(c->list[j]->name, str, len)) { - cscipher_tobe = c->list[j]; - break; + warn = 0; + for (i = 0; i < n_preferred_ciphers; i++) { + const struct ssh2_ciphers *c = preferred_ciphers[i]; + if (!c) { + warn = 1; + } else { + for (j = 0; j < c->nciphers; j++) { + if (in_commasep_string(c->list[j]->name, str, len)) { + cscipher_tobe = c->list[j]; + break; + } } } - if (cscipher_tobe) + if (cscipher_tobe) { + if (warn) + askcipher(cscipher_tobe->name, 1); break; + } + } + if (!cscipher_tobe) { + bombout(("Couldn't agree a client-to-server cipher (available: %s)", str)); + crReturn(0); } + ssh2_pkt_getstring(&str, &len); /* server->client cipher */ - for (i = 0; i < lenof(ciphers) + 1; i++) { - const struct ssh2_ciphers *c = - i == 0 ? preferred_cipher : ciphers[i - 1]; - for (j = 0; j < c->nciphers; j++) { - if (in_commasep_string(c->list[j]->name, str, len)) { - sccipher_tobe = c->list[j]; - break; + warn = 0; + for (i = 0; i < n_preferred_ciphers; i++) { + const struct ssh2_ciphers *c = preferred_ciphers[i]; + if (!c) { + warn = 1; + } else { + for (j = 0; j < c->nciphers; j++) { + if (in_commasep_string(c->list[j]->name, str, len)) { + sccipher_tobe = c->list[j]; + break; + } } } - if (sccipher_tobe) + if (sccipher_tobe) { + if (warn) + askcipher(sccipher_tobe->name, 2); break; + } + } + if (!sccipher_tobe) { + bombout(("Couldn't agree a server-to-client cipher (available: %s)", str)); + crReturn(0); } + ssh2_pkt_getstring(&str, &len); /* client->server mac */ for (i = 0; i < nmacs; i++) { if (in_commasep_string(maclist[i]->name, str, len)) { @@ -3178,15 +3509,6 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt) } /* - * Expect SSH2_MSG_NEWKEYS from server. - */ - crWaitUntil(ispkt); - if (pktin.type != SSH2_MSG_NEWKEYS) { - bombout(("expected new-keys packet from server")); - crReturn(0); - } - - /* * Authenticate remote host: verify host key. (We've already * checked the signature of the exchange hash.) */ @@ -3209,6 +3531,15 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt) ssh2_pkt_send(); /* + * Expect SSH2_MSG_NEWKEYS from server. + */ + crWaitUntil(ispkt); + if (pktin.type != SSH2_MSG_NEWKEYS) { + bombout(("expected new-keys packet from server")); + crReturn(0); + } + + /* * Create and initialise session keys. */ cscipher = cscipher_tobe; @@ -3272,33 +3603,49 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt) static void ssh2_add_channel_data(struct ssh_channel *c, char *buf, int len) { - if (c->v2.outbufsize < c->v2.outbuflen + len) { - c->v2.outbufsize = c->v2.outbuflen + len + 1024; - c->v2.outbuffer = srealloc(c->v2.outbuffer, c->v2.outbufsize); - } - memcpy(c->v2.outbuffer + c->v2.outbuflen, buf, len); - c->v2.outbuflen += len; + bufchain_add(&c->v.v2.outbuffer, buf, len); } /* * Attempt to send data on an SSH2 channel. */ -static void ssh2_try_send(struct ssh_channel *c) +static int ssh2_try_send(struct ssh_channel *c) { - while (c->v2.remwindow > 0 && c->v2.outbuflen > 0) { - unsigned len = c->v2.remwindow; - if (len > c->v2.outbuflen) - len = c->v2.outbuflen; - if (len > c->v2.remmaxpkt) - len = c->v2.remmaxpkt; + while (c->v.v2.remwindow > 0 && bufchain_size(&c->v.v2.outbuffer) > 0) { + int len; + void *data; + bufchain_prefix(&c->v.v2.outbuffer, &data, &len); + if ((unsigned)len > c->v.v2.remwindow) + len = c->v.v2.remwindow; + if ((unsigned)len > c->v.v2.remmaxpkt) + len = c->v.v2.remmaxpkt; ssh2_pkt_init(SSH2_MSG_CHANNEL_DATA); ssh2_pkt_adduint32(c->remoteid); ssh2_pkt_addstring_start(); - ssh2_pkt_addstring_data(c->v2.outbuffer, len); + ssh2_pkt_addstring_data(data, len); + ssh2_pkt_send(); + bufchain_consume(&c->v.v2.outbuffer, len); + c->v.v2.remwindow -= len; + } + + /* + * After having sent as much data as we can, return the amount + * still buffered. + */ + return bufchain_size(&c->v.v2.outbuffer); +} + +/* + * Potentially enlarge the window on an SSH2 channel. + */ +static void ssh2_set_window(struct ssh_channel *c, unsigned newwin) +{ + if (newwin > c->v.v2.locwindow) { + ssh2_pkt_init(SSH2_MSG_CHANNEL_WINDOW_ADJUST); + ssh2_pkt_adduint32(c->remoteid); + ssh2_pkt_adduint32(newwin - c->v.v2.locwindow); ssh2_pkt_send(); - c->v2.outbuflen -= len; - memmove(c->v2.outbuffer, c->v2.outbuffer + len, c->v2.outbuflen); - c->v2.remwindow -= len; + c->v.v2.locwindow = newwin; } } @@ -3497,7 +3844,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) * This is a further prompt in keyboard-interactive * authentication. Do nothing. */ - } else if (!pktin.type != SSH2_MSG_USERAUTH_FAILURE) { + } else if (pktin.type != SSH2_MSG_USERAUTH_FAILURE) { bombout(("Strange packet received during authentication: type %d", pktin.type)); crReturnV; @@ -3563,66 +3910,12 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) in_commasep_string("publickey", methods, methlen); can_passwd = in_commasep_string("password", methods, methlen); - can_passwd = - in_commasep_string("password", methods, methlen); - can_keyb_inter = + can_keyb_inter = cfg.try_ki_auth && in_commasep_string("keyboard-interactive", methods, methlen); } method = 0; - if (!method && can_keyb_inter && !tried_keyb_inter) { - method = AUTH_KEYBOARD_INTERACTIVE; - type = AUTH_TYPE_KEYBOARD_INTERACTIVE; - tried_keyb_inter = TRUE; - - ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST); - ssh2_pkt_addstring(username); - ssh2_pkt_addstring("ssh-connection"); /* service requested */ - ssh2_pkt_addstring("keyboard-interactive"); /* method */ - ssh2_pkt_addstring(""); /* lang */ - ssh2_pkt_addstring(""); - ssh2_pkt_send(); - - crWaitUntilV(ispkt); - if (pktin.type != SSH2_MSG_USERAUTH_INFO_REQUEST) { - if (pktin.type == SSH2_MSG_USERAUTH_FAILURE) - gotit = TRUE; - logevent("Keyboard-interactive authentication refused"); - type = AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET; - continue; - } - - kbd_inter_running = TRUE; - } - - if (kbd_inter_running) { - method = AUTH_KEYBOARD_INTERACTIVE; - type = AUTH_TYPE_KEYBOARD_INTERACTIVE; - tried_keyb_inter = TRUE; - - /* 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; - ssh2_pkt_getstring(&name, &name_len); - ssh2_pkt_getstring(&inst, &inst_len); - ssh2_pkt_getstring(&lang, &lang_len); - if (name_len > 0) - c_write_untrusted(name, name_len); - if (inst_len > 0) - c_write_untrusted(inst, inst_len); - num_prompts = ssh2_pkt_getuint32(); - - ssh2_pkt_getstring(&prompt, &prompt_len); - strncpy(pwprompt, prompt, sizeof(pwprompt)); - need_pw = TRUE; - - echo = ssh2_pkt_getbool(); - } - } - if (!method && can_pubkey && agent_exists() && !tried_agent) { /* * Attempt public-key authentication using Pageant. @@ -3816,6 +4109,60 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) } } + if (!method && can_keyb_inter && !tried_keyb_inter) { + method = AUTH_KEYBOARD_INTERACTIVE; + type = AUTH_TYPE_KEYBOARD_INTERACTIVE; + tried_keyb_inter = TRUE; + + ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST); + ssh2_pkt_addstring(username); + ssh2_pkt_addstring("ssh-connection"); /* service requested */ + ssh2_pkt_addstring("keyboard-interactive"); /* method */ + ssh2_pkt_addstring(""); /* lang */ + ssh2_pkt_addstring(""); + ssh2_pkt_send(); + + crWaitUntilV(ispkt); + if (pktin.type != SSH2_MSG_USERAUTH_INFO_REQUEST) { + if (pktin.type == SSH2_MSG_USERAUTH_FAILURE) + gotit = TRUE; + logevent("Keyboard-interactive authentication refused"); + type = AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET; + continue; + } + + kbd_inter_running = TRUE; + } + + if (kbd_inter_running) { + method = AUTH_KEYBOARD_INTERACTIVE; + type = AUTH_TYPE_KEYBOARD_INTERACTIVE; + tried_keyb_inter = TRUE; + + /* 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; + ssh2_pkt_getstring(&name, &name_len); + ssh2_pkt_getstring(&inst, &inst_len); + ssh2_pkt_getstring(&lang, &lang_len); + if (name_len > 0) + c_write_untrusted(name, name_len); + if (inst_len > 0) + c_write_untrusted(inst, inst_len); + 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; + + echo = ssh2_pkt_getbool(); + } + } + if (!method && can_passwd) { method = AUTH_PASSWORD; sprintf(pwprompt, "%.90s@%.90s's password: ", username, @@ -4047,7 +4394,8 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN); ssh2_pkt_addstring("session"); ssh2_pkt_adduint32(mainchan->localid); - ssh2_pkt_adduint32(0x8000UL); /* our window size */ + mainchan->v.v2.locwindow = OUR_V2_WINSIZE; + ssh2_pkt_adduint32(mainchan->v.v2.locwindow); /* our window size */ ssh2_pkt_adduint32(0x4000UL); /* our max pkt size */ ssh2_pkt_send(); crWaitUntilV(ispkt); @@ -4063,10 +4411,9 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) mainchan->remoteid = ssh2_pkt_getuint32(); mainchan->type = CHAN_MAINSESSION; mainchan->closes = 0; - mainchan->v2.remwindow = ssh2_pkt_getuint32(); - mainchan->v2.remmaxpkt = ssh2_pkt_getuint32(); - mainchan->v2.outbuffer = NULL; - mainchan->v2.outbuflen = mainchan->v2.outbufsize = 0; + mainchan->v.v2.remwindow = ssh2_pkt_getuint32(); + mainchan->v.v2.remmaxpkt = ssh2_pkt_getuint32(); + bufchain_init(&mainchan->v.v2.outbuffer); add234(ssh_channels, mainchan); logevent("Opened channel for session"); @@ -4095,13 +4442,14 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) c = find234(ssh_channels, &i, ssh_channelfind); if (!c) continue; /* nonexistent channel */ - c->v2.remwindow += ssh2_pkt_getuint32(); + c->v.v2.remwindow += ssh2_pkt_getuint32(); } } while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST); if (pktin.type != SSH2_MSG_CHANNEL_SUCCESS) { if (pktin.type != SSH2_MSG_CHANNEL_FAILURE) { - bombout(("Server got confused by X11 forwarding request")); + bombout(("Unexpected response to X11 forwarding request:" + " packet type %d", pktin.type)); crReturnV; } logevent("X11 forwarding refused"); @@ -4183,13 +4531,15 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) c = find234(ssh_channels, &i, ssh_channelfind); if (!c) continue;/* nonexistent channel */ - c->v2.remwindow += ssh2_pkt_getuint32(); + c->v.v2.remwindow += ssh2_pkt_getuint32(); } } while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST); if (pktin.type != SSH2_MSG_REQUEST_SUCCESS) { if (pktin.type != SSH2_MSG_REQUEST_FAILURE) { - bombout(("Server got confused by port forwarding request")); + bombout(("Unexpected response to port " + "forwarding request: packet type %d", + pktin.type)); crReturnV; } logevent("Server refused this port forwarding"); @@ -4221,14 +4571,14 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) c = find234(ssh_channels, &i, ssh_channelfind); if (!c) continue; /* nonexistent channel */ - c->v2.remwindow += ssh2_pkt_getuint32(); + c->v.v2.remwindow += ssh2_pkt_getuint32(); } } while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST); if (pktin.type != SSH2_MSG_CHANNEL_SUCCESS) { if (pktin.type != SSH2_MSG_CHANNEL_FAILURE) { - bombout( - ("Server got confused by agent forwarding request")); + bombout(("Unexpected response to agent forwarding request:" + " packet type %d", pktin.type)); crReturnV; } logevent("Agent forwarding refused"); @@ -4264,13 +4614,14 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) c = find234(ssh_channels, &i, ssh_channelfind); if (!c) continue; /* nonexistent channel */ - c->v2.remwindow += ssh2_pkt_getuint32(); + c->v.v2.remwindow += ssh2_pkt_getuint32(); } } while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST); if (pktin.type != SSH2_MSG_CHANNEL_SUCCESS) { if (pktin.type != SSH2_MSG_CHANNEL_FAILURE) { - bombout(("Server got confused by pty request")); + bombout(("Unexpected response to pty request:" + " packet type %d", pktin.type)); crReturnV; } c_write_str("Server refused to allocate pty\r\n"); @@ -4283,43 +4634,71 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) } /* - * Start a shell or a remote command. + * Start a shell or a remote command. We may have to attempt + * this twice if the config data has provided a second choice + * of command. */ - ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST); - ssh2_pkt_adduint32(mainchan->remoteid); /* recipient channel */ - if (cfg.ssh_subsys) { - ssh2_pkt_addstring("subsystem"); - ssh2_pkt_addbool(1); /* want reply */ - ssh2_pkt_addstring(cfg.remote_cmd_ptr); - } else if (*cfg.remote_cmd_ptr) { - ssh2_pkt_addstring("exec"); - ssh2_pkt_addbool(1); /* want reply */ - ssh2_pkt_addstring(cfg.remote_cmd_ptr); - } else { - ssh2_pkt_addstring("shell"); - ssh2_pkt_addbool(1); /* want reply */ - } - ssh2_pkt_send(); - do { - crWaitUntilV(ispkt); - if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) { - unsigned i = ssh2_pkt_getuint32(); - struct ssh_channel *c; - c = find234(ssh_channels, &i, ssh_channelfind); - if (!c) - continue; /* nonexistent channel */ - c->v2.remwindow += ssh2_pkt_getuint32(); + while (1) { + int subsys; + char *cmd; + + if (ssh_fallback_cmd) { + subsys = cfg.ssh_subsys2; + cmd = cfg.remote_cmd_ptr2; + } else { + subsys = cfg.ssh_subsys; + cmd = cfg.remote_cmd_ptr; } - } while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST); - if (pktin.type != SSH2_MSG_CHANNEL_SUCCESS) { - if (pktin.type != SSH2_MSG_CHANNEL_FAILURE) { - bombout(("Server got confused by shell/command request")); + + ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST); + ssh2_pkt_adduint32(mainchan->remoteid); /* recipient channel */ + if (subsys) { + ssh2_pkt_addstring("subsystem"); + ssh2_pkt_addbool(1); /* want reply */ + ssh2_pkt_addstring(cmd); + } else if (*cmd) { + ssh2_pkt_addstring("exec"); + ssh2_pkt_addbool(1); /* want reply */ + ssh2_pkt_addstring(cmd); + } else { + ssh2_pkt_addstring("shell"); + ssh2_pkt_addbool(1); /* want reply */ + } + ssh2_pkt_send(); + do { + crWaitUntilV(ispkt); + if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) { + unsigned i = ssh2_pkt_getuint32(); + struct ssh_channel *c; + c = find234(ssh_channels, &i, ssh_channelfind); + if (!c) + continue; /* nonexistent channel */ + c->v.v2.remwindow += ssh2_pkt_getuint32(); + } + } while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST); + if (pktin.type != SSH2_MSG_CHANNEL_SUCCESS) { + if (pktin.type != SSH2_MSG_CHANNEL_FAILURE) { + bombout(("Unexpected response to shell/command request:" + " packet type %d", pktin.type)); + crReturnV; + } + /* + * We failed to start the command. If this is the + * fallback command, we really are finished; if it's + * not, and if the fallback command exists, try falling + * back to it before complaining. + */ + if (!ssh_fallback_cmd && cfg.remote_cmd_ptr2 != NULL) { + logevent("Primary command failed; attempting fallback"); + ssh_fallback_cmd = TRUE; + continue; + } + bombout(("Server refused to start a shell/command")); crReturnV; + } else { + logevent("Started a shell/command"); } - bombout(("Server refused to start a shell/command")); - crReturnV; - } else { - logevent("Started a shell/command"); + break; } ssh_state = SSH_STATE_SESSION; @@ -4331,7 +4710,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) /* * Transfer data! */ - ldisc_send(NULL, 0); /* cause ldisc to notice changes */ + ldisc_send(NULL, 0, 0); /* cause ldisc to notice changes */ ssh_send_ok = 1; while (1) { static int try_send; @@ -4352,17 +4731,20 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) continue; /* extended but not stderr */ ssh2_pkt_getstring(&data, &length); if (data) { + int bufsize; + c->v.v2.locwindow -= length; switch (c->type) { case CHAN_MAINSESSION: - from_backend(pktin.type == - SSH2_MSG_CHANNEL_EXTENDED_DATA, data, - length); + bufsize = + from_backend(pktin.type == + SSH2_MSG_CHANNEL_EXTENDED_DATA, + data, length); break; case CHAN_X11: - x11_send(c->u.x11.s, data, length); + bufsize = x11_send(c->u.x11.s, data, length); break; case CHAN_SOCKDATA: - pfd_send(c->u.pfd.s, data, length); + bufsize = pfd_send(c->u.pfd.s, data, length); break; case CHAN_AGENT: while (length > 0) { @@ -4412,24 +4794,20 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) c->u.a.lensofar = 0; } } + bufsize = 0; break; } /* - * Enlarge the window again at the remote - * side, just in case it ever runs down and - * they fail to send us any more data. + * If we are not buffering too much data, + * enlarge the window again at the remote side. */ - ssh2_pkt_init(SSH2_MSG_CHANNEL_WINDOW_ADJUST); - ssh2_pkt_adduint32(c->remoteid); - ssh2_pkt_adduint32(length); - ssh2_pkt_send(); + if (bufsize < OUR_V2_WINSIZE) + ssh2_set_window(c, OUR_V2_WINSIZE - bufsize); } } else if (pktin.type == SSH2_MSG_DISCONNECT) { ssh_state = SSH_STATE_CLOSED; logevent("Received disconnect message"); crReturnV; - } else if (pktin.type == SSH2_MSG_CHANNEL_REQUEST) { - continue; /* exit status et al; ignore (FIXME?) */ } else if (pktin.type == SSH2_MSG_CHANNEL_EOF) { unsigned i = ssh2_pkt_getuint32(); struct ssh_channel *c; @@ -4458,24 +4836,31 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) c = find234(ssh_channels, &i, ssh_channelfind); if (!c) continue; /* nonexistent channel */ - if (c->closes == 0) { - ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE); - ssh2_pkt_adduint32(c->remoteid); - ssh2_pkt_send(); - } /* Do pre-close processing on the channel. */ switch (c->type) { case CHAN_MAINSESSION: break; /* nothing to see here, move along */ case CHAN_X11: + if (c->u.x11.s != NULL) + x11_close(c->u.x11.s); + sshfwd_close(c); break; case CHAN_AGENT: + sshfwd_close(c); break; case CHAN_SOCKDATA: + if (c->u.pfd.s != NULL) + pfd_close(c->u.pfd.s); + sshfwd_close(c); break; } + if (c->closes == 0) { + ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE); + ssh2_pkt_adduint32(c->remoteid); + ssh2_pkt_send(); + } del234(ssh_channels, c); - sfree(c->v2.outbuffer); + bufchain_clear(&c->v.v2.outbuffer); sfree(c); /* @@ -4498,7 +4883,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) c = find234(ssh_channels, &i, ssh_channelfind); if (!c) continue; /* nonexistent channel */ - c->v2.remwindow += ssh2_pkt_getuint32(); + c->v.v2.remwindow += ssh2_pkt_getuint32(); try_send = TRUE; } else if (pktin.type == SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) { unsigned i = ssh2_pkt_getuint32(); @@ -4510,12 +4895,77 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) continue; /* dunno why they're confirming this */ c->remoteid = ssh2_pkt_getuint32(); c->type = CHAN_SOCKDATA; - c->closes = 0; - c->v2.remwindow = ssh2_pkt_getuint32(); - c->v2.remmaxpkt = ssh2_pkt_getuint32(); - c->v2.outbuffer = NULL; - c->v2.outbuflen = c->v2.outbufsize = 0; - pfd_confirm(c->u.pfd.s); + 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) { + /* + * We have a pending close on this channel, + * which we decided on before the server acked + * the channel open. So now we know the + * remoteid, we can close it again. + */ + ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE); + ssh2_pkt_adduint32(c->remoteid); + ssh2_pkt_send(); + } + } else if (pktin.type == SSH2_MSG_CHANNEL_OPEN_FAILURE) { + unsigned i = ssh2_pkt_getuint32(); + struct ssh_channel *c; + c = find234(ssh_channels, &i, ssh_channelfind); + if (!c) + continue; /* nonexistent channel */ + if (c->type != CHAN_SOCKDATA_DORMANT) + continue; /* dunno why they're failing this */ + + logevent("Forwarded connection refused by server"); + + pfd_close(c->u.pfd.s); + + del234(ssh_channels, c); + sfree(c); + } else if (pktin.type == SSH2_MSG_CHANNEL_REQUEST) { + unsigned localid; + char *type; + int typelen, want_reply; + struct ssh_channel *c; + + localid = ssh2_pkt_getuint32(); + ssh2_pkt_getstring(&type, &typelen); + want_reply = ssh2_pkt_getbool(); + + /* + * First, check that the channel exists. Otherwise, + * we can instantly disconnect with a rude message. + */ + c = find234(ssh_channels, &localid, ssh_channelfind); + if (!c) { + char buf[80]; + sprintf(buf, "Received channel request for nonexistent" + " channel %d", localid); + logevent(buf); + ssh2_pkt_init(SSH2_MSG_DISCONNECT); + ssh2_pkt_adduint32(SSH2_DISCONNECT_BY_APPLICATION); + ssh2_pkt_addstring(buf); + ssh2_pkt_addstring("en"); /* language tag */ + ssh2_pkt_send(); + connection_fatal(buf); + ssh_state = SSH_STATE_CLOSED; + crReturnV; + } + + /* + * We don't recognise any form of channel request, + * so we now either ignore the request or respond + * with CHANNEL_FAILURE, depending on want_reply. + */ + if (want_reply) { + ssh2_pkt_init(SSH2_MSG_CHANNEL_FAILURE); + ssh2_pkt_adduint32(c->remoteid); + ssh2_pkt_send(); + } } else if (pktin.type == SSH2_MSG_CHANNEL_OPEN) { char *type; int typelen; @@ -4588,15 +5038,15 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) } else { c->localid = alloc_channel_id(); c->closes = 0; - c->v2.remwindow = winsize; - c->v2.remmaxpkt = pktsize; - c->v2.outbuffer = NULL; - c->v2.outbuflen = c->v2.outbufsize = 0; + c->v.v2.locwindow = OUR_V2_WINSIZE; + c->v.v2.remwindow = winsize; + c->v.v2.remmaxpkt = pktsize; + bufchain_init(&c->v.v2.outbuffer); add234(ssh_channels, c); ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); ssh2_pkt_adduint32(c->remoteid); ssh2_pkt_adduint32(c->localid); - ssh2_pkt_adduint32(0x8000UL); /* our window size */ + ssh2_pkt_adduint32(c->v.v2.locwindow); ssh2_pkt_adduint32(0x4000UL); /* our max pkt size */ ssh2_pkt_send(); } @@ -4617,8 +5067,27 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) /* * Try to send data on all channels if we can. */ - for (i = 0; NULL != (c = index234(ssh_channels, i)); i++) - ssh2_try_send(c); + for (i = 0; NULL != (c = index234(ssh_channels, i)); i++) { + int bufsize = ssh2_try_send(c); + if (bufsize == 0) { + switch (c->type) { + case CHAN_MAINSESSION: + /* stdin need not receive an unthrottle + * notification since it will be polled */ + break; + case CHAN_X11: + x11_unthrottle(c->u.x11.s); + break; + case CHAN_AGENT: + /* agent sockets are request/response and need no + * buffer management */ + break; + case CHAN_SOCKDATA: + pfd_unthrottle(c->u.pfd.s); + break; + } + } + } } } @@ -4640,7 +5109,7 @@ static void ssh2_protocol(unsigned char *in, int inlen, int ispkt) * * Returns an error message, or NULL on success. */ -static char *ssh_init(char *host, int port, char **realhost) +static char *ssh_init(char *host, int port, char **realhost, int nodelay) { char *p; @@ -4652,8 +5121,11 @@ static char *ssh_init(char *host, int port, char **realhost) ssh_send_ok = 0; ssh_editing = 0; ssh_echoing = 0; + ssh1_throttle_count = 0; + ssh_overall_bufsize = 0; + ssh_fallback_cmd = 0; - p = connect_to_host(host, port, realhost); + p = connect_to_host(host, port, realhost, nodelay); if (p != NULL) return p; @@ -4663,12 +5135,44 @@ static char *ssh_init(char *host, int port, char **realhost) /* * Called to send data down the Telnet connection. */ -static void ssh_send(char *buf, int len) +static int ssh_send(char *buf, int len) { if (s == NULL || ssh_protocol == NULL) - return; + return 0; ssh_protocol(buf, len, 0); + + return ssh_sendbuffer(); +} + +/* + * Called to query the current amount of buffered stdin data. + */ +static int ssh_sendbuffer(void) +{ + int override_value; + + if (s == NULL || ssh_protocol == NULL) + return 0; + + /* + * If the SSH socket itself has backed up, add the total backup + * size on that to any individual buffer on the stdin channel. + */ + override_value = 0; + if (ssh_throttled_all) + override_value = ssh_overall_bufsize; + + if (ssh_version == 1) { + return override_value; + } else if (ssh_version == 2) { + if (!mainchan || mainchan->closes > 0) + return override_value; + else + return override_value + bufchain_size(&mainchan->v.v2.outbuffer); + } + + return 0; } /* @@ -4762,6 +5266,23 @@ void *new_sock_channel(Socket s) return c; } +/* + * This is called when stdout/stderr (the entity to which + * from_backend sends data) manages to clear some backlog. + */ +void ssh_unthrottle(int bufsize) +{ + if (ssh_version == 1) { + if (ssh1_stdout_throttling && bufsize < SSH1_BUFFER_LIMIT) { + ssh1_stdout_throttling = 0; + ssh1_throttle(-1); + } + } else { + if (mainchan && mainchan->closes == 0) + ssh2_set_window(mainchan, OUR_V2_WINSIZE - bufsize); + } +} + void ssh_send_port_open(void *channel, char *hostname, int port, char *org) { struct ssh_channel *c = (struct ssh_channel *)channel; @@ -4781,7 +5302,8 @@ void ssh_send_port_open(void *channel, char *hostname, int port, char *org) ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN); ssh2_pkt_addstring("direct-tcpip"); ssh2_pkt_adduint32(c->localid); - ssh2_pkt_adduint32(0x8000UL); /* our window size */ + c->v.v2.locwindow = OUR_V2_WINSIZE; + ssh2_pkt_adduint32(c->v.v2.locwindow);/* our window size */ ssh2_pkt_adduint32(0x4000UL); /* our max pkt size */ ssh2_pkt_addstring(hostname); ssh2_pkt_adduint32(port); @@ -4820,10 +5342,12 @@ static int ssh_ldisc(int option) Backend ssh_backend = { ssh_init, ssh_send, + ssh_sendbuffer, ssh_size, ssh_special, ssh_socket, ssh_sendok, ssh_ldisc, + ssh_unthrottle, 22 };