X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/5471d09ad63fc6216fb9c2a3b52ca9c93821a054..fd5e5847eb0f834ce8124f0574bd3cfaf878db53:/ssh.c diff --git a/ssh.c b/ssh.c index be346593..2c538239 100644 --- a/ssh.c +++ b/ssh.c @@ -428,6 +428,13 @@ 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; @@ -1862,31 +1869,45 @@ 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"); @@ -2649,12 +2670,26 @@ 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) @@ -2992,7 +3027,7 @@ 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; @@ -3009,7 +3044,8 @@ 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; @@ -3018,21 +3054,40 @@ 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: + /* Not supported in SSH2; silently drop */ + 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 @@ -3069,23 +3124,23 @@ 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(","); } } @@ -3171,30 +3226,44 @@ 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; + } } 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; + } } ssh2_pkt_getstring(&str, &len); /* client->server mac */ for (i = 0; i < nmacs; i++) { @@ -4444,43 +4513,70 @@ 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->v.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(("Server got confused by shell/command request")); + 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; @@ -4834,6 +4930,7 @@ static char *ssh_init(char *host, int port, char **realhost) ssh_echoing = 0; ssh1_throttle_count = 0; ssh_overall_bufsize = 0; + ssh_fallback_cmd = 0; p = connect_to_host(host, port, realhost); if (p != NULL)