X-Git-Url: https://git.distorted.org.uk/~mdw/sgt/putty/blobdiff_plain/50b1791f4a51423f2d84976d649f4c18083717f2..ddecd643be56256929ae1c45bebb8e39ae032225:/ssh.c diff --git a/ssh.c b/ssh.c index 795dc4f4..08ff8d97 100644 --- a/ssh.c +++ b/ssh.c @@ -68,6 +68,10 @@ #define SSH1_AUTH_TIS 5 /* 0x5 */ #define SSH1_AUTH_CCARD 16 /* 0x10 */ +#define SSH1_PROTOFLAG_SCREEN_NUMBER 1 /* 0x1 */ +/* Mask for protoflags we will echo back to server if seen */ +#define SSH1_PROTOFLAGS_SUPPORTED 0 /* 0x1 */ + #define SSH2_MSG_DISCONNECT 1 /* 0x1 */ #define SSH2_MSG_IGNORE 2 /* 0x2 */ #define SSH2_MSG_UNIMPLEMENTED 3 /* 0x3 */ @@ -114,6 +118,29 @@ #define SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE 9 /* 0x9 */ #define SSH2_DISCONNECT_CONNECTION_LOST 10 /* 0xa */ #define SSH2_DISCONNECT_BY_APPLICATION 11 /* 0xb */ +#define SSH2_DISCONNECT_TOO_MANY_CONNECTIONS 12 /* 0xc */ +#define SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER 13 /* 0xd */ +#define SSH2_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE 14 /* 0xe */ +#define SSH2_DISCONNECT_ILLEGAL_USER_NAME 15 /* 0xf */ + +static const char *const ssh2_disconnect_reasons[] = { + NULL, + "SSH_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT", + "SSH_DISCONNECT_PROTOCOL_ERROR", + "SSH_DISCONNECT_KEY_EXCHANGE_FAILED", + "SSH_DISCONNECT_HOST_AUTHENTICATION_FAILED", + "SSH_DISCONNECT_MAC_ERROR", + "SSH_DISCONNECT_COMPRESSION_ERROR", + "SSH_DISCONNECT_SERVICE_NOT_AVAILABLE", + "SSH_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED", + "SSH_DISCONNECT_HOST_KEY_NOT_VERIFIABLE", + "SSH_DISCONNECT_CONNECTION_LOST", + "SSH_DISCONNECT_BY_APPLICATION", + "SSH_DISCONNECT_TOO_MANY_CONNECTIONS", + "SSH_DISCONNECT_AUTH_CANCELLED_BY_USER", + "SSH_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE", + "SSH_DISCONNECT_ILLEGAL_USER_NAME", +}; #define SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED 1 /* 0x1 */ #define SSH2_OPEN_CONNECT_FAILED 2 /* 0x2 */ @@ -256,6 +283,8 @@ static Socket s = NULL; static unsigned char session_key[32]; static int ssh1_compressing; +static int ssh1_remote_protoflags; +static int ssh1_local_protoflags; static int ssh_agentfwd_enabled; static int ssh_X11_fwd_enabled; static int ssh_remote_bugs; @@ -347,6 +376,16 @@ static void c_write (char *buf, int len) { from_backend(1, buf, len); } +static void c_write_untrusted(char *buf, int len) { + int i; + for (i = 0; i < len; i++) { + if (buf[i] == '\n') + c_write("\r\n", 2); + else if ((buf[i] & 0x60) || (buf[i] == '\r')) + c_write(buf+i, 1); + } +} + static void c_write_str (char *buf) { c_write(buf, strlen(buf)); } @@ -432,11 +471,13 @@ next_packet: unsigned char *decompblk; int decomplen; #if 0 - int i; - debug(("Packet payload pre-decompression:\n")); - for (i = -1; i < pktin.length; i++) - debug((" %02x", (unsigned char)pktin.body[i])); - debug(("\r\n")); + { + int i; + debug(("Packet payload pre-decompression:\n")); + for (i = -1; i < pktin.length; i++) + debug((" %02x", (unsigned char)pktin.body[i])); + debug(("\r\n")); + } #endif zlib_decompress_block(pktin.body-1, pktin.length+1, &decompblk, &decomplen); @@ -453,10 +494,13 @@ next_packet: sfree(decompblk); pktin.length = decomplen-1; #if 0 - debug(("Packet payload post-decompression:\n")); - for (i = -1; i < pktin.length; i++) - debug((" %02x", (unsigned char)pktin.body[i])); - debug(("\r\n")); + { + int i; + debug(("Packet payload post-decompression:\n")); + for (i = -1; i < pktin.length; i++) + debug((" %02x", (unsigned char)pktin.body[i])); + debug(("\r\n")); + } #endif } @@ -489,6 +533,20 @@ next_packet: goto next_packet; } + if (pktin.type == SSH1_MSG_DISCONNECT) { + /* log reason code in disconnect message */ + char buf[256]; + int msglen = GET_32BIT(pktin.body); + int nowlen; + strcpy(buf, "Remote sent disconnect: "); + nowlen = strlen(buf); + if (msglen > sizeof(buf)-nowlen-1) + msglen = sizeof(buf)-nowlen-1; + memcpy(buf+nowlen, pktin.body+4, msglen); + buf[nowlen+msglen] = '\0'; + logevent(buf); + } + crFinish(0); } @@ -628,6 +686,28 @@ next_packet: if (pktin.type == SSH2_MSG_IGNORE || pktin.type == SSH2_MSG_DEBUG) goto next_packet; /* FIXME: print DEBUG message */ + if (pktin.type == SSH2_MSG_DISCONNECT) { + /* log reason code in disconnect message */ + char buf[256]; + int reason = GET_32BIT(pktin.data+6); + int msglen = GET_32BIT(pktin.data+10); + int nowlen; + if (reason > 0 && reason < lenof(ssh2_disconnect_reasons)) { + sprintf(buf, "Received disconnect message (%s)", + ssh2_disconnect_reasons[reason]); + } else { + sprintf(buf, "Received disconnect message (unknown type %d)", reason); + } + logevent(buf); + strcpy(buf, "Disconnection message text: "); + nowlen = strlen(buf); + if (msglen > sizeof(buf)-nowlen-1) + msglen = sizeof(buf)-nowlen-1; + memcpy(buf+nowlen, pktin.data+14, msglen); + buf[nowlen+msglen] = '\0'; + logevent(buf); + } + crFinish(0); } @@ -907,7 +987,7 @@ static void ssh2_pkt_addstring(char *data) { } static char *ssh2_mpint_fmt(Bignum b, int *len) { unsigned char *p; - int i, n = (ssh1_bignum_bitcount(b)+7)/8; + int i, n = (bignum_bitcount(b)+7)/8; p = smalloc(n + 1); if (!p) fatalbox("out of memory"); @@ -1107,7 +1187,9 @@ static void ssh_detect_bugs(char *vstring) { char *imp; /* pointer to implementation part */ imp = vstring; imp += strcspn(imp, "-"); + if (*imp) imp++; imp += strcspn(imp, "-"); + if (*imp) imp++; ssh_remote_bugs = 0; @@ -1135,10 +1217,11 @@ static void ssh_detect_bugs(char *vstring) { } static int do_ssh_init(unsigned char c) { - static char *vsp; + static char vslen; static char version[10]; - static char vstring[80]; - static char vlog[sizeof(vstring)+20]; + static char *vstring; + static int vstrsize; + static char *vlog; static int i; crBegin; @@ -1158,13 +1241,18 @@ static int do_ssh_init(unsigned char c) { crReturn(1); /* get another character */ } + vstring = smalloc(16); + vstrsize = 16; strcpy(vstring, "SSH-"); - vsp = vstring+4; + vslen = 4; i = 0; while (1) { crReturn(1); /* get another char */ - if (vsp < vstring+sizeof(vstring)-1) - *vsp++ = c; + if (vslen >= vstrsize-1) { + vstrsize += 16; + vstring = srealloc(vstring, vstrsize); + } + vstring[vslen++] = c; if (i >= 0) { if (c == '-') { version[i] = '\0'; @@ -1179,11 +1267,13 @@ static int do_ssh_init(unsigned char c) { ssh_agentfwd_enabled = FALSE; rdpkt2_state.incoming_sequence = 0; - *vsp = 0; + vstring[vslen] = 0; + vlog = smalloc(20 + vslen); sprintf(vlog, "Server version: %s", vstring); ssh_detect_bugs(vstring); vlog[strcspn(vlog, "\r\n")] = '\0'; logevent(vlog); + sfree(vlog); /* * Server version "1.99" means we can choose whether we use v1 @@ -1193,18 +1283,19 @@ static int do_ssh_init(unsigned char c) { /* * This is a v2 server. Begin v2 protocol. */ - char *verstring = "SSH-2.0-PuTTY"; + char verstring[80], vlog[100]; + sprintf(verstring, "SSH-2.0-%s", sshver); SHA_Init(&exhashbase); /* * Hash our version string and their version string. */ sha_string(&exhashbase, verstring, strlen(verstring)); sha_string(&exhashbase, vstring, strcspn(vstring, "\r\n")); - sprintf(vstring, "%s\n", verstring); sprintf(vlog, "We claim version: %s", verstring); logevent(vlog); + strcat(verstring, "\n"); logevent("Using SSH protocol version 2"); - sk_write(s, vstring, strlen(vstring)); + sk_write(s, verstring, strlen(verstring)); ssh_protocol = ssh2_protocol; ssh_version = 2; s_rdpkt = ssh2_rdpkt; @@ -1212,19 +1303,23 @@ static int do_ssh_init(unsigned char c) { /* * This is a v1 server. Begin v1 protocol. */ - sprintf(vstring, "SSH-%s-PuTTY\n", - (ssh_versioncmp(version, "1.5") <= 0 ? version : "1.5")); - sprintf(vlog, "We claim version: %s", vstring); - vlog[strcspn(vlog, "\r\n")] = '\0'; + char verstring[80], vlog[100]; + sprintf(verstring, "SSH-%s-%s", + (ssh_versioncmp(version, "1.5") <= 0 ? version : "1.5"), + sshver); + sprintf(vlog, "We claim version: %s", verstring); logevent(vlog); + strcat(verstring, "\n"); logevent("Using SSH protocol version 1"); - sk_write(s, vstring, strlen(vstring)); + sk_write(s, verstring, strlen(verstring)); ssh_protocol = ssh1_protocol; ssh_version = 1; s_rdpkt = ssh1_rdpkt; } ssh_state = SSH_STATE_BEFORE_SIZE; + sfree(vstring); + crFinish(0); } @@ -1406,9 +1501,13 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) logevent(logmsg); } + ssh1_remote_protoflags = GET_32BIT(pktin.body+8+i+j); supported_ciphers_mask = GET_32BIT(pktin.body+12+i+j); supported_auths_mask = GET_32BIT(pktin.body+16+i+j); + ssh1_local_protoflags = ssh1_remote_protoflags & SSH1_PROTOFLAGS_SUPPORTED; + ssh1_local_protoflags |= SSH1_PROTOFLAG_SCREEN_NUMBER; + MD5Init(&md5c); MD5Update(&md5c, keystr2, hostkey.bytes); MD5Update(&md5c, keystr1, servkey.bytes); @@ -1470,6 +1569,11 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) 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")); + crReturn(0); + } } switch (cipher_type) { case SSH_CIPHER_3DES: logevent("Using 3DES encryption"); break; @@ -1482,7 +1586,7 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) PKT_DATA, cookie, 8, PKT_CHAR, (len*8) >> 8, PKT_CHAR, (len*8) & 0xFF, PKT_DATA, rsabuf, len, - PKT_INT, 0, + PKT_INT, ssh1_local_protoflags, PKT_END); logevent("Trying to enable encryption..."); @@ -1608,7 +1712,8 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) request[4] = SSH1_AGENTC_REQUEST_RSA_IDENTITIES; agent_query(request, 5, &r, &responselen); response = (unsigned char *)r; - if (response) { + if (response && responselen >= 5 && + response[4] == SSH1_AGENT_RSA_IDENTITIES_ANSWER) { p = response + 5; nkeys = GET_32BIT(p); p += 4; { char buf[64]; sprintf(buf, "Pageant has %d SSH1 keys", nkeys); @@ -1648,7 +1753,7 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) PUT_32BIT(agentreq, len); q = agentreq + 4; *q++ = SSH1_AGENTC_RSA_CHALLENGE; - PUT_32BIT(q, ssh1_bignum_bitcount(key.modulus)); + PUT_32BIT(q, bignum_bitcount(key.modulus)); q += 4; q += ssh1_write_bignum(q, key.exponent); q += ssh1_write_bignum(q, key.modulus); @@ -2041,10 +2146,16 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) { char proto[20], data[64]; logevent("Requesting X11 forwarding"); x11_invent_auth(proto, sizeof(proto), data, sizeof(data)); - send_packet(SSH1_CMSG_X11_REQUEST_FORWARDING, - PKT_STR, proto, PKT_STR, data, - PKT_INT, 0, - PKT_END); + if (ssh1_local_protoflags & SSH1_PROTOFLAG_SCREEN_NUMBER) { + send_packet(SSH1_CMSG_X11_REQUEST_FORWARDING, + PKT_STR, proto, PKT_STR, data, + PKT_INT, 0, + PKT_END); + } else { + send_packet(SSH1_CMSG_X11_REQUEST_FORWARDING, + PKT_STR, proto, PKT_STR, data, + PKT_END); + } do { crReturnV; } while (!ispkt); if (pktin.type != SSH1_SMSG_SUCCESS && pktin.type != SSH1_SMSG_FAILURE) { bombout(("Protocol confusion")); @@ -2093,8 +2204,8 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) { zlib_decompress_init(); } - if (*cfg.remote_cmd) - send_packet(SSH1_CMSG_EXEC_CMD, PKT_STR, cfg.remote_cmd, PKT_END); + 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"); @@ -2200,7 +2311,8 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) { if (c) { int closetype; closetype = (pktin.type == SSH1_MSG_CHANNEL_CLOSE ? 1 : 2); - send_packet(pktin.type, PKT_INT, c->remoteid, PKT_END); + if (!(c->closes & closetype)) + send_packet(pktin.type, PKT_INT, c->remoteid, PKT_END); if ((c->closes == 0) && (c->type == CHAN_X11)) { logevent("X11 connection closed"); assert(c->u.x11.s != NULL); @@ -2869,7 +2981,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) */ logevent("No username provided. Abandoning session."); ssh_state = SSH_STATE_CLOSED; - crReturn(1); + crReturnV; } } else { c_write_str("login as: "); @@ -2943,7 +3055,21 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) if (!gotit) crWaitUntilV(ispkt); while (pktin.type == SSH2_MSG_USERAUTH_BANNER) { - /* FIXME: should support this */ + char *banner; + int size; + /* + * 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.) + */ + if (flags & (FLAG_VERBOSE | FLAG_INTERACTIVE)) { + ssh2_pkt_getstring(&banner, &size); + if (banner) + c_write_untrusted(banner, size); + } crWaitUntilV(ispkt); } if (pktin.type == SSH2_MSG_USERAUTH_SUCCESS) { @@ -2955,6 +3081,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) if (pktin.type != SSH2_MSG_USERAUTH_FAILURE) { bombout(("Strange packet received during authentication: type %d", pktin.type)); + crReturnV; } gotit = FALSE; @@ -3035,7 +3162,8 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) request[4] = SSH2_AGENTC_REQUEST_IDENTITIES; agent_query(request, 5, &r, &responselen); response = (unsigned char *)r; - if (response) { + if (response && responselen >= 5 && + response[4] == SSH2_AGENT_IDENTITIES_ANSWER) { p = response + 5; nkeys = GET_32BIT(p); p += 4; { char buf[64]; sprintf(buf, "Pageant has %d SSH2 keys", nkeys); @@ -3071,9 +3199,11 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) continue; } - c_write_str("Authenticating with public key \""); - c_write(commentp, commentlen); - c_write_str("\" from agent\r\n"); + if (flags & FLAG_VERBOSE) { + c_write_str("Authenticating with public key \""); + c_write(commentp, commentlen); + c_write_str("\" from agent\r\n"); + } /* * Server is willing to accept the key. @@ -3456,7 +3586,6 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) * Potentially enable agent forwarding. */ if (cfg.agentfwd && agent_exists()) { - char proto[20], data[64]; logevent("Requesting OpenSSH-style agent forwarding"); ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST); ssh2_pkt_adduint32(mainchan->remoteid); @@ -3540,11 +3669,11 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) if (cfg.ssh_subsys) { ssh2_pkt_addstring("subsystem"); ssh2_pkt_addbool(1); /* want reply */ - ssh2_pkt_addstring(cfg.remote_cmd); - } else if (*cfg.remote_cmd) { + 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); + ssh2_pkt_addstring(cfg.remote_cmd_ptr); } else { ssh2_pkt_addstring("shell"); ssh2_pkt_addbool(1); /* want reply */ @@ -3731,7 +3860,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) c = find234(ssh_channels, &i, ssh_channelfind); if (!c) continue; /* nonexistent channel */ - mainchan->v2.remwindow += ssh2_pkt_getuint32(); + c->v2.remwindow += ssh2_pkt_getuint32(); try_send = TRUE; } else if (pktin.type == SSH2_MSG_CHANNEL_OPEN) { char *type;