X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/6b4e00eed3caa13d4636f5d7bc49e59da6fd3ffc..7e78000d8966255e919e3d8753fd784f4559ee55:/ssh.c diff --git a/ssh.c b/ssh.c index 7c4caa57..3af4ba94 100644 --- a/ssh.c +++ b/ssh.c @@ -19,8 +19,9 @@ if ((flags & FLAG_STDERR) && (flags & FLAG_VERBOSE)) \ fprintf(stderr, "%s\n", s); } -#define bombout(msg) ( ssh_state = SSH_STATE_CLOSED, sk_close(s), \ - s = NULL, connection_fatal msg ) +#define bombout(msg) ( ssh_state = SSH_STATE_CLOSED, \ + (s ? sk_close(s), s = NULL : 0), \ + connection_fatal msg ) #define SSH1_MSG_DISCONNECT 1 /* 0x1 */ #define SSH1_SMSG_PUBLIC_KEY 2 /* 0x2 */ @@ -46,11 +47,17 @@ #define SSH1_MSG_CHANNEL_DATA 23 /* 0x17 */ #define SSH1_MSG_CHANNEL_CLOSE 24 /* 0x18 */ #define SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION 25 /* 0x19 */ +#define SSH1_SMSG_X11_OPEN 27 /* 0x1b */ +#define SSH1_CMSG_PORT_FORWARD_REQUEST 28 /* 0x1c */ +#define SSH1_MSG_PORT_OPEN 29 /* 0x1d */ #define SSH1_CMSG_AGENT_REQUEST_FORWARDING 30 /* 0x1e */ #define SSH1_SMSG_AGENT_OPEN 31 /* 0x1f */ -#define SSH1_CMSG_EXIT_CONFIRMATION 33 /* 0x21 */ #define SSH1_MSG_IGNORE 32 /* 0x20 */ +#define SSH1_CMSG_EXIT_CONFIRMATION 33 /* 0x21 */ +#define SSH1_CMSG_X11_REQUEST_FORWARDING 34 /* 0x22 */ +#define SSH1_CMSG_AUTH_RHOSTS_RSA 35 /* 0x23 */ #define SSH1_MSG_DEBUG 36 /* 0x24 */ +#define SSH1_CMSG_REQUEST_COMPRESSION 37 /* 0x25 */ #define SSH1_CMSG_AUTH_TIS 39 /* 0x27 */ #define SSH1_SMSG_AUTH_TIS_CHALLENGE 40 /* 0x28 */ #define SSH1_CMSG_AUTH_TIS_RESPONSE 41 /* 0x29 */ @@ -61,15 +68,6 @@ #define SSH1_AUTH_TIS 5 /* 0x5 */ #define SSH1_AUTH_CCARD 16 /* 0x10 */ -#define SSH_AGENTC_REQUEST_RSA_IDENTITIES 1 /* 0x1 */ -#define SSH_AGENT_RSA_IDENTITIES_ANSWER 2 /* 0x2 */ -#define SSH_AGENTC_RSA_CHALLENGE 3 /* 0x3 */ -#define SSH_AGENT_RSA_RESPONSE 4 /* 0x4 */ -#define SSH_AGENT_FAILURE 5 /* 0x5 */ -#define SSH_AGENT_SUCCESS 6 /* 0x6 */ -#define SSH_AGENTC_ADD_RSA_IDENTITY 7 /* 0x7 */ -#define SSH_AGENTC_REMOVE_RSA_IDENTITY 8 /* 0x8 */ - #define SSH2_MSG_DISCONNECT 1 /* 0x1 */ #define SSH2_MSG_IGNORE 2 /* 0x2 */ #define SSH2_MSG_UNIMPLEMENTED 3 /* 0x3 */ @@ -80,6 +78,10 @@ #define SSH2_MSG_NEWKEYS 21 /* 0x15 */ #define SSH2_MSG_KEXDH_INIT 30 /* 0x1e */ #define SSH2_MSG_KEXDH_REPLY 31 /* 0x1f */ +#define SSH2_MSG_KEX_DH_GEX_REQUEST 30 /* 0x1e */ +#define SSH2_MSG_KEX_DH_GEX_GROUP 31 /* 0x1f */ +#define SSH2_MSG_KEX_DH_GEX_INIT 32 /* 0x20 */ +#define SSH2_MSG_KEX_DH_GEX_REPLY 33 /* 0x21 */ #define SSH2_MSG_USERAUTH_REQUEST 50 /* 0x32 */ #define SSH2_MSG_USERAUTH_FAILURE 51 /* 0x33 */ #define SSH2_MSG_USERAUTH_SUCCESS 52 /* 0x34 */ @@ -101,6 +103,18 @@ #define SSH2_MSG_CHANNEL_SUCCESS 99 /* 0x63 */ #define SSH2_MSG_CHANNEL_FAILURE 100 /* 0x64 */ +#define SSH2_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT 1 /* 0x1 */ +#define SSH2_DISCONNECT_PROTOCOL_ERROR 2 /* 0x2 */ +#define SSH2_DISCONNECT_KEY_EXCHANGE_FAILED 3 /* 0x3 */ +#define SSH2_DISCONNECT_HOST_AUTHENTICATION_FAILED 4 /* 0x4 */ +#define SSH2_DISCONNECT_MAC_ERROR 5 /* 0x5 */ +#define SSH2_DISCONNECT_COMPRESSION_ERROR 6 /* 0x6 */ +#define SSH2_DISCONNECT_SERVICE_NOT_AVAILABLE 7 /* 0x7 */ +#define SSH2_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED 8 /* 0x8 */ +#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_OPEN_ADMINISTRATIVELY_PROHIBITED 1 /* 0x1 */ #define SSH2_OPEN_CONNECT_FAILED 2 /* 0x2 */ #define SSH2_OPEN_UNKNOWN_CHANNEL_TYPE 3 /* 0x3 */ @@ -108,6 +122,12 @@ #define SSH2_EXTENDED_DATA_STDERR 1 /* 0x1 */ +/* + * Various remote-bug flags. + */ +#define BUG_CHOKES_ON_SSH1_IGNORE 1 +#define BUG_SSH2_HMAC 2 + #define GET_32BIT(cp) \ (((unsigned long)(unsigned char)(cp)[0] << 24) | \ ((unsigned long)(unsigned char)(cp)[1] << 16) | \ @@ -141,11 +161,10 @@ enum { PKT_END, PKT_INT, PKT_CHAR, PKT_DATA, PKT_STR, PKT_BIGNUM }; #define crWaitUntil(c) do { crReturn(0); } while (!(c)) #define crWaitUntilV(c) do { crReturnV; } while (!(c)) -extern const struct ssh_cipher ssh_3des; -extern const struct ssh_cipher ssh_3des_ssh2; -extern const struct ssh_cipher ssh_des; -extern const struct ssh_cipher ssh_blowfish_ssh1; -extern const struct ssh_cipher ssh_blowfish_ssh2; +extern char *x11_init (Socket *, char *, void *); +extern void x11_close (Socket); +extern void x11_send (Socket , char *, int); +extern void x11_invent_auth(char *, int, char *, int); /* * Ciphers for SSH2. We miss out single-DES because it isn't @@ -153,15 +172,17 @@ extern const struct ssh_cipher ssh_blowfish_ssh2; * SSH1. (3DES uses outer chaining; Blowfish has the opposite * endianness and different-sized keys.) */ -const static struct ssh_cipher *ciphers[] = { &ssh_blowfish_ssh2, &ssh_3des_ssh2 }; - -extern const struct ssh_kex ssh_diffiehellman; -const static struct ssh_kex *kex_algs[] = { &ssh_diffiehellman }; +const static struct ssh2_ciphers *ciphers[] = { + &ssh2_aes, + &ssh2_blowfish, + &ssh2_3des, +}; -extern const struct ssh_hostkey ssh_dss; -const static struct ssh_hostkey *hostkey_algs[] = { &ssh_dss }; +const static struct ssh_kex *kex_algs[] = { + &ssh_diffiehellman_gex, + &ssh_diffiehellman }; -extern const struct ssh_mac ssh_md5, ssh_sha1, ssh_sha1_buggy; +const static struct ssh_signkey *hostkey_algs[] = { &ssh_rsa, &ssh_dss }; static void nullmac_key(unsigned char *key) { } static void nullmac_generate(unsigned char *blk, int len, unsigned long seq) { } @@ -174,10 +195,27 @@ const static struct ssh_mac *macs[] = { const static struct ssh_mac *buggymacs[] = { &ssh_sha1_buggy, &ssh_md5, &ssh_mac_none }; +static void ssh_comp_none_init(void) { } +static int ssh_comp_none_block(unsigned char *block, int len, + unsigned char **outblock, int *outlen) { + return 0; +} +static int ssh_comp_none_disable(void) { return 0; } const static struct ssh_compress ssh_comp_none = { - "none" + "none", + ssh_comp_none_init, ssh_comp_none_block, + ssh_comp_none_init, ssh_comp_none_block, + ssh_comp_none_disable +}; +extern const struct ssh_compress ssh_zlib; +const static struct ssh_compress *compressions[] = { + &ssh_zlib, &ssh_comp_none }; + +enum { /* channel types */ + CHAN_MAINSESSION, + CHAN_X11, + CHAN_AGENT, }; -const static struct ssh_compress *compressions[] = { &ssh_comp_none }; /* * 2-3-4 tree storing channels. @@ -186,17 +224,20 @@ 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 ssh_agent_channel { unsigned char *message; unsigned char msglen[4]; int lensofar, totallen; } a; - struct ssh2_data_channel { - unsigned char *outbuffer; - unsigned outbuflen, outbufsize; - unsigned remwindow, remmaxpkt; - } v2; + struct ssh_x11_channel { + Socket s; + } x11; } u; }; @@ -209,46 +250,59 @@ struct Packet { long maxlen; }; -static SHA_State exhash; +static SHA_State exhash, exhashbase; static Socket s = NULL; static unsigned char session_key[32]; +static int ssh1_compressing; +static int ssh_agentfwd_enabled; +static int ssh_X11_fwd_enabled; +static int ssh_remote_bugs; static const struct ssh_cipher *cipher = NULL; -static const struct ssh_cipher *cscipher = NULL; -static const struct ssh_cipher *sccipher = NULL; +static const struct ssh2_cipher *cscipher = NULL; +static const struct ssh2_cipher *sccipher = NULL; static const struct ssh_mac *csmac = NULL; static const struct ssh_mac *scmac = NULL; static const struct ssh_compress *cscomp = NULL; static const struct ssh_compress *sccomp = NULL; static const struct ssh_kex *kex = NULL; -static const struct ssh_hostkey *hostkey = NULL; -int (*ssh_get_password)(const char *prompt, char *str, int maxlen) = 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; static int ssh_send_ok; +static int ssh_echoing, ssh_editing; static tree234 *ssh_channels; /* indexed by local id */ static struct ssh_channel *mainchan; /* primary session channel */ static enum { + SSH_STATE_PREPACKET, SSH_STATE_BEFORE_SIZE, SSH_STATE_INTERMED, SSH_STATE_SESSION, SSH_STATE_CLOSED -} ssh_state = SSH_STATE_BEFORE_SIZE; +} ssh_state = SSH_STATE_PREPACKET; -static int size_needed = FALSE; +static int size_needed = FALSE, eof_needed = FALSE; static struct Packet pktin = { 0, 0, NULL, NULL, 0 }; static struct Packet pktout = { 0, 0, NULL, NULL, 0 }; +static unsigned char *deferred_send_data = NULL; +static int deferred_len = 0, deferred_size = 0; static int ssh_version; 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 void ssh2_add_channel_data(struct ssh_channel *c, char *buf, int len); static int (*s_rdpkt)(unsigned char **data, int *datalen); @@ -293,6 +347,10 @@ static void c_write (char *buf, int len) { from_backend(1, buf, len); } +static void c_write_str (char *buf) { + c_write(buf, strlen(buf)); +} + /* * Collect incoming data in the incoming packet buffer. * Decipher and verify the packet when it is completely read. @@ -331,8 +389,8 @@ next_packet: if (pktin.maxlen < st->biglen) { pktin.maxlen = st->biglen; - pktin.data = (pktin.data == NULL ? malloc(st->biglen+APIEXTRA) : - realloc(pktin.data, st->biglen+APIEXTRA)); + pktin.data = (pktin.data == NULL ? smalloc(st->biglen+APIEXTRA) : + srealloc(pktin.data, st->biglen+APIEXTRA)); if (!pktin.data) fatalbox("Out of memory"); } @@ -361,9 +419,6 @@ next_packet: debug(("\r\n")); #endif - pktin.type = pktin.data[st->pad]; - pktin.body = pktin.data + st->pad + 1; - st->realcrc = crc32(pktin.data, st->biglen-4); st->gotcrc = GET_32BIT(pktin.data+st->biglen-4); if (st->gotcrc != st->realcrc) { @@ -371,6 +426,40 @@ next_packet: crReturn(0); } + pktin.body = pktin.data + st->pad + 1; + + if (ssh1_compressing) { + 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")); +#endif + zlib_decompress_block(pktin.body-1, pktin.length+1, + &decompblk, &decomplen); + + if (pktin.maxlen < st->pad + decomplen) { + pktin.maxlen = st->pad + decomplen; + pktin.data = srealloc(pktin.data, pktin.maxlen+APIEXTRA); + pktin.body = pktin.data + st->pad + 1; + if (!pktin.data) + fatalbox("Out of memory"); + } + + memcpy(pktin.body-1, decompblk, decomplen); + 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")); +#endif + } + if (pktin.type == SSH1_SMSG_STDOUT_DATA || pktin.type == SSH1_SMSG_STDERR_DATA || pktin.type == SSH1_MSG_DEBUG || @@ -383,6 +472,8 @@ next_packet: } } + pktin.type = pktin.body[-1]; + if (pktin.type == SSH1_MSG_DEBUG) { /* log debug message */ char buf[80]; @@ -419,8 +510,8 @@ next_packet: if (pktin.maxlen < st->cipherblk) { pktin.maxlen = st->cipherblk; - pktin.data = (pktin.data == NULL ? malloc(st->cipherblk+APIEXTRA) : - realloc(pktin.data, st->cipherblk+APIEXTRA)); + pktin.data = (pktin.data == NULL ? smalloc(st->cipherblk+APIEXTRA) : + srealloc(pktin.data, st->cipherblk+APIEXTRA)); if (!pktin.data) fatalbox("Out of memory"); } @@ -467,8 +558,8 @@ next_packet: */ if (pktin.maxlen < st->packetlen+st->maclen) { pktin.maxlen = st->packetlen+st->maclen; - pktin.data = (pktin.data == NULL ? malloc(pktin.maxlen+APIEXTRA) : - realloc(pktin.data, pktin.maxlen+APIEXTRA)); + pktin.data = (pktin.data == NULL ? smalloc(pktin.maxlen+APIEXTRA) : + srealloc(pktin.data, pktin.maxlen+APIEXTRA)); if (!pktin.data) fatalbox("Out of memory"); } @@ -503,6 +594,34 @@ next_packet: } st->incoming_sequence++; /* whether or not we MACed */ + /* + * Decompress packet payload. + */ + { + unsigned char *newpayload; + int newlen; + if (sccomp && sccomp->decompress(pktin.data+5, pktin.length-5, + &newpayload, &newlen)) { + if (pktin.maxlen < newlen+5) { + pktin.maxlen = newlen+5; + pktin.data = (pktin.data == NULL ? smalloc(pktin.maxlen+APIEXTRA) : + srealloc(pktin.data, pktin.maxlen+APIEXTRA)); + if (!pktin.data) + fatalbox("Out of memory"); + } + pktin.length = 5 + newlen; + memcpy(pktin.data+5, newpayload, newlen); +#if 0 + debug(("Post-decompression payload:\r\n")); + for (st->i = 0; st->i < newlen; st->i++) + debug((" %02x", (unsigned char)pktin.data[5+st->i])); + debug(("\r\n")); +#endif + + sfree(newpayload); + } + } + pktin.savedpos = 6; pktin.type = pktin.data[5]; @@ -512,7 +631,7 @@ next_packet: crFinish(0); } -static void s_wrpkt_start(int type, int len) { +static void ssh1_pktout_size(int len) { int pad, biglen; len += 5; /* type and CRC */ @@ -525,29 +644,56 @@ static void s_wrpkt_start(int type, int len) { #ifdef MSCRYPTOAPI /* Allocate enough buffer space for extra block * for MS CryptEncrypt() */ - pktout.data = (pktout.data == NULL ? malloc(biglen+12) : - realloc(pktout.data, biglen+12)); + pktout.data = (pktout.data == NULL ? smalloc(biglen+12) : + srealloc(pktout.data, biglen+12)); #else - pktout.data = (pktout.data == NULL ? malloc(biglen+4) : - realloc(pktout.data, biglen+4)); + pktout.data = (pktout.data == NULL ? smalloc(biglen+4) : + srealloc(pktout.data, biglen+4)); #endif if (!pktout.data) fatalbox("Out of memory"); } + pktout.body = pktout.data+4+pad+1; +} +static void s_wrpkt_start(int type, int len) { + ssh1_pktout_size(len); pktout.type = type; - pktout.body = pktout.data+4+pad+1; } -static void s_wrpkt(void) { +static int s_wrpkt_prepare(void) { int pad, len, biglen, i; unsigned long crc; + pktout.body[-1] = pktout.type; + +#if 0 + debug(("Packet payload pre-compression:\n")); + for (i = -1; i < pktout.length; i++) + debug((" %02x", (unsigned char)pktout.body[i])); + debug(("\r\n")); +#endif + + if (ssh1_compressing) { + unsigned char *compblk; + int complen; + zlib_compress_block(pktout.body-1, pktout.length+1, + &compblk, &complen); + ssh1_pktout_size(complen-1); + memcpy(pktout.body-1, compblk, complen); + sfree(compblk); +#if 0 + debug(("Packet payload post-compression:\n")); + for (i = -1; i < pktout.length; i++) + debug((" %02x", (unsigned char)pktout.body[i])); + debug(("\r\n")); +#endif + } + len = pktout.length + 5; /* type and CRC */ pad = 8 - (len%8); biglen = len + pad; - pktout.body[-1] = pktout.type; for (i=0; iencrypt(pktout.data+4, biglen); - sk_write(s, pktout.data, biglen+4); + return biglen+4; +} + +static void s_wrpkt(void) { + int len; + len = s_wrpkt_prepare(); + sk_write(s, pktout.data, len); +} + +static void s_wrpkt_defer(void) { + int len; + len = s_wrpkt_prepare(); + if (deferred_len + len > deferred_size) { + deferred_size = deferred_len + len + 128; + deferred_send_data = srealloc(deferred_send_data, deferred_size); + } + memcpy(deferred_send_data+deferred_len, pktout.data, len); + deferred_len += len; } /* - * Construct a packet with the specified contents and - * send it to the server. + * Construct a packet with the specified contents. */ -static void send_packet(int pkttype, ...) +static void construct_packet(int pkttype, va_list ap1, va_list ap2) { - va_list args; unsigned char *p, *argp, argchar; unsigned long argint; int pktlen, argtype, arglen; Bignum bn; pktlen = 0; - va_start(args, pkttype); - while ((argtype = va_arg(args, int)) != PKT_END) { + while ((argtype = va_arg(ap1, int)) != PKT_END) { switch (argtype) { case PKT_INT: - (void) va_arg(args, int); + (void) va_arg(ap1, int); pktlen += 4; break; case PKT_CHAR: - (void) va_arg(args, char); + (void) va_arg(ap1, char); pktlen++; break; case PKT_DATA: - (void) va_arg(args, unsigned char *); - arglen = va_arg(args, int); + (void) va_arg(ap1, unsigned char *); + arglen = va_arg(ap1, int); pktlen += arglen; break; case PKT_STR: - argp = va_arg(args, unsigned char *); + argp = va_arg(ap1, unsigned char *); arglen = strlen(argp); pktlen += 4 + arglen; break; case PKT_BIGNUM: - bn = va_arg(args, Bignum); + bn = va_arg(ap1, Bignum); pktlen += ssh1_bignum_length(bn); break; default: assert(0); } } - va_end(args); s_wrpkt_start(pkttype, pktlen); p = pktout.body; - va_start(args, pkttype); - while ((argtype = va_arg(args, int)) != PKT_END) { + while ((argtype = va_arg(ap2, int)) != PKT_END) { switch (argtype) { case PKT_INT: - argint = va_arg(args, int); + argint = va_arg(ap2, int); PUT_32BIT(p, argint); p += 4; break; case PKT_CHAR: - argchar = va_arg(args, unsigned char); + argchar = va_arg(ap2, unsigned char); *p = argchar; p++; break; case PKT_DATA: - argp = va_arg(args, unsigned char *); - arglen = va_arg(args, int); + argp = va_arg(ap2, unsigned char *); + arglen = va_arg(ap2, int); memcpy(p, argp, arglen); p += arglen; break; case PKT_STR: - argp = va_arg(args, unsigned char *); + argp = va_arg(ap2, unsigned char *); arglen = strlen(argp); PUT_32BIT(p, arglen); memcpy(p + 4, argp, arglen); p += 4 + arglen; break; case PKT_BIGNUM: - bn = va_arg(args, Bignum); + bn = va_arg(ap2, Bignum); p += ssh1_write_bignum(p, bn); break; } } - va_end(args); +} +static void send_packet(int pkttype, ...) { + va_list ap1, ap2; + va_start(ap1, pkttype); + va_start(ap2, pkttype); + construct_packet(pkttype, ap1, ap2); s_wrpkt(); } +static void defer_packet(int pkttype, ...) { + va_list ap1, ap2; + va_start(ap1, pkttype); + va_start(ap2, pkttype); + construct_packet(pkttype, ap1, ap2); + s_wrpkt_defer(); +} + static int ssh_versioncmp(char *a, char *b) { char *ae, *be; unsigned long av, bv; @@ -667,8 +838,8 @@ static int ssh_versioncmp(char *a, char *b) { /* - * Utility routine for putting an SSH-protocol `string' into a SHA - * state. + * Utility routines for putting an SSH-protocol `string' and + * `uint32' into a SHA state. */ #include static void sha_string(SHA_State *s, void *str, int len) { @@ -678,18 +849,27 @@ static void sha_string(SHA_State *s, void *str, int len) { SHA_Bytes(s, str, len); } +static void sha_uint32(SHA_State *s, unsigned i) { + unsigned char intblk[4]; + PUT_32BIT(intblk, i); + SHA_Bytes(s, intblk, 4); +} + /* * SSH2 packet construction functions. */ -static void ssh2_pkt_adddata(void *data, int len) { - pktout.length += len; - if (pktout.maxlen < pktout.length) { - pktout.maxlen = pktout.length + 256; - pktout.data = (pktout.data == NULL ? malloc(pktout.maxlen+APIEXTRA) : - realloc(pktout.data, pktout.maxlen+APIEXTRA)); +static void ssh2_pkt_ensure(int length) { + if (pktout.maxlen < length) { + pktout.maxlen = length + 256; + pktout.data = (pktout.data == NULL ? smalloc(pktout.maxlen+APIEXTRA) : + srealloc(pktout.data, pktout.maxlen+APIEXTRA)); if (!pktout.data) fatalbox("Out of memory"); } +} +static void ssh2_pkt_adddata(void *data, int len) { + pktout.length += len; + ssh2_pkt_ensure(pktout.length); memcpy(pktout.data+pktout.length-len, data, len); } static void ssh2_pkt_addbyte(unsigned char byte) { @@ -727,20 +907,18 @@ static void ssh2_pkt_addstring(char *data) { } static char *ssh2_mpint_fmt(Bignum b, int *len) { unsigned char *p; - int i, n = b[0]; - p = malloc(n * 2 + 1); + int i, n = (ssh1_bignum_bitcount(b)+7)/8; + p = smalloc(n + 1); if (!p) fatalbox("out of memory"); p[0] = 0; - for (i = 0; i < n; i++) { - p[i*2+1] = (b[n-i] >> 8) & 0xFF; - p[i*2+2] = (b[n-i] ) & 0xFF; - } + for (i = 1; i <= n; i++) + p[i] = bignum_byte(b, n-i); i = 0; - while (p[i] == 0 && (p[i+1] & 0x80) == 0) + while (i <= n && p[i] == 0 && (p[i+1] & 0x80) == 0) i++; - memmove(p, p+i, n*2+1-i); - *len = n*2+1-i; + memmove(p, p+i, n+1-i); + *len = n+1-i; return p; } static void ssh2_pkt_addmp(Bignum b) { @@ -749,20 +927,48 @@ static void ssh2_pkt_addmp(Bignum b) { p = ssh2_mpint_fmt(b, &len); ssh2_pkt_addstring_start(); ssh2_pkt_addstring_data(p, len); - free(p); + sfree(p); } -static void ssh2_pkt_send(void) { + +/* + * Construct an SSH2 final-form packet: compress it, encrypt it, + * put the MAC on it. Final packet, ready to be sent, is stored in + * pktout.data. Total length is returned. + */ +static int ssh2_pkt_construct(void) { int cipherblk, maclen, padding, i; static unsigned long outgoing_sequence = 0; /* + * Compress packet payload. + */ +#if 0 + debug(("Pre-compression payload:\r\n")); + for (i = 5; i < pktout.length; i++) + debug((" %02x", (unsigned char)pktout.data[i])); + debug(("\r\n")); +#endif + { + unsigned char *newpayload; + int newlen; + if (cscomp && cscomp->compress(pktout.data+5, pktout.length-5, + &newpayload, &newlen)) { + pktout.length = 5; + ssh2_pkt_adddata(newpayload, newlen); + sfree(newpayload); + } + } + + /* * Add padding. At least four bytes, and must also bring total * length (minus MAC) up to a multiple of the block size. */ - cipherblk = cipher ? cipher->blksize : 8; /* block size */ + cipherblk = cscipher ? cscipher->blksize : 8; /* block size */ cipherblk = cipherblk < 8 ? 8 : cipherblk; /* or 8 if blksize < 8 */ padding = 4; padding += (cipherblk - (pktout.length + padding) % cipherblk) % cipherblk; + maclen = csmac ? csmac->len : 0; + ssh2_pkt_ensure(pktout.length + padding + maclen); pktout.data[4] = padding; for (i = 0; i < padding; i++) pktout.data[pktout.length + i] = random_byte(); @@ -781,9 +987,49 @@ static void ssh2_pkt_send(void) { if (cscipher) cscipher->encrypt(pktout.data, pktout.length + padding); - maclen = csmac ? csmac->len : 0; - sk_write(s, pktout.data, pktout.length + padding + maclen); + /* Ready-to-send packet starts at pktout.data. We return length. */ + return pktout.length + padding + maclen; +} + +/* + * Construct and send an SSH2 packet immediately. + */ +static void ssh2_pkt_send(void) { + int len = ssh2_pkt_construct(); + sk_write(s, pktout.data, len); +} + +/* + * Construct an SSH2 packet and add it to a deferred data block. + * Useful for sending multiple packets in a single sk_write() call, + * to prevent a traffic-analysing listener from being able to work + * out the length of any particular packet (such as the password + * packet). + * + * Note that because SSH2 sequence-numbers its packets, this can + * NOT be used as an m4-style `defer' allowing packets to be + * constructed in one order and sent in another. + */ +static void ssh2_pkt_defer(void) { + int len = ssh2_pkt_construct(); + if (deferred_len + len > deferred_size) { + deferred_size = deferred_len + len + 128; + deferred_send_data = srealloc(deferred_send_data, deferred_size); + } + memcpy(deferred_send_data+deferred_len, pktout.data, len); + deferred_len += len; +} + +/* + * Send the whole deferred data block constructed by + * ssh2_pkt_defer() or SSH1's defer_packet(). + */ +static void ssh_pkt_defersend(void) { + sk_write(s, deferred_send_data, deferred_len); + deferred_len = deferred_size = 0; + sfree(deferred_send_data); + deferred_send_data = NULL; } #if 0 @@ -795,7 +1041,7 @@ void bndebug(char *string, Bignum b) { for (i = 0; i < len; i++) debug((" %02x", p[i])); debug(("\r\n")); - free(p); + sfree(p); } #endif @@ -804,7 +1050,7 @@ static void sha_mpint(SHA_State *s, Bignum b) { int len; p = ssh2_mpint_fmt(b, &len); sha_string(s, p, len); - free(p); + sfree(p); } /* @@ -818,6 +1064,14 @@ static unsigned long ssh2_pkt_getuint32(void) { pktin.savedpos += 4; return value; } +static int ssh2_pkt_getbool(void) { + unsigned long value; + if (pktin.length - pktin.savedpos < 1) + return 0; /* arrgh, no way to decline (FIXME?) */ + value = pktin.data[pktin.savedpos] != 0; + pktin.savedpos++; + return value; +} static void ssh2_pkt_getstring(char **p, int *length) { *p = NULL; if (pktin.length - pktin.savedpos < 4) @@ -831,7 +1085,7 @@ static void ssh2_pkt_getstring(char **p, int *length) { } static Bignum ssh2_pkt_getmp(void) { char *p; - int i, j, length; + int length; Bignum b; ssh2_pkt_getstring(&p, &length); @@ -841,18 +1095,45 @@ static Bignum ssh2_pkt_getmp(void) { bombout(("internal error: Can't handle negative mpints")); return NULL; } - b = newbn((length+1)/2); - for (i = 0; i < length; i++) { - j = length - 1 - i; - if (j & 1) - b[j/2+1] |= ((unsigned char)p[i]) << 8; - else - b[j/2+1] |= ((unsigned char)p[i]); - } - while (b[0] > 1 && b[b[0]] == 0) b[0]--; + b = bignum_from_bytes(p, length); return b; } +/* + * Examine the remote side's version string and compare it against + * a list of known buggy implementations. + */ +static void ssh_detect_bugs(char *vstring) { + char *imp; /* pointer to implementation part */ + imp = vstring; + imp += strcspn(imp, "-"); + imp += strcspn(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")) { + /* + * These versions don't support SSH1_MSG_IGNORE, so we have + * to use a different defence against password length + * sniffing. + */ + ssh_remote_bugs |= BUG_CHOKES_ON_SSH1_IGNORE; + logevent("We believe remote version has SSH1 ignore bug"); + } + + 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)) { + /* + * These versions have the HMAC bug. + */ + ssh_remote_bugs |= BUG_SSH2_HMAC; + logevent("We believe remote version has SSH2 HMAC bug"); + } +} + static int do_ssh_init(unsigned char c) { static char *vsp; static char version[10]; @@ -895,10 +1176,12 @@ static int do_ssh_init(unsigned char c) { break; } + ssh_agentfwd_enabled = FALSE; rdpkt2_state.incoming_sequence = 0; *vsp = 0; sprintf(vlog, "Server version: %s", vstring); + ssh_detect_bugs(vstring); vlog[strcspn(vlog, "\r\n")] = '\0'; logevent(vlog); @@ -911,12 +1194,12 @@ static int do_ssh_init(unsigned char c) { * This is a v2 server. Begin v2 protocol. */ char *verstring = "SSH-2.0-PuTTY"; - SHA_Init(&exhash); + SHA_Init(&exhashbase); /* * Hash our version string and their version string. */ - sha_string(&exhash, verstring, strlen(verstring)); - sha_string(&exhash, vstring, strcspn(vstring, "\r\n")); + 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); @@ -940,6 +1223,7 @@ static int do_ssh_init(unsigned char c) { ssh_version = 1; s_rdpkt = ssh1_rdpkt; } + ssh_state = SSH_STATE_BEFORE_SIZE; crFinish(0); } @@ -986,13 +1270,20 @@ static void ssh_gotdata(unsigned char *data, int datalen) crFinishV; } -static int ssh_receive(Socket s, int urgent, char *data, int len) { - if (!len) { - /* Connection has closed. */ - sk_close(s); - s = NULL; - return 0; +static int ssh_closing (Plug plug, char *error_msg, int error_code, int calling_back) { + ssh_state = SSH_STATE_CLOSED; + sk_close(s); + s = NULL; + if (error_msg) { + /* A socket error has occurred. */ + connection_fatal (error_msg); + } else { + /* Otherwise, the remote side closed the connection normally. */ } + return 0; +} + +static int ssh_receive(Plug plug, int urgent, char *data, int len) { ssh_gotdata (data, len); if (ssh_state == SSH_STATE_CLOSED) { if (s) { @@ -1011,6 +1302,11 @@ static int ssh_receive(Socket s, int urgent, char *data, int len) { */ static char *connect_to_host(char *host, int port, char **realhost) { + static struct plug_function_table fn_table = { + ssh_closing, + ssh_receive + }, *fn_table_ptr = &fn_table; + SockAddr addr; char *err; #ifdef FWHACK @@ -1018,7 +1314,7 @@ static char *connect_to_host(char *host, int port, char **realhost) int FWport; #endif - savedhost = malloc(1+strlen(host)); + savedhost = smalloc(1+strlen(host)); if (!savedhost) fatalbox("Out of memory"); strcpy(savedhost, host); @@ -1048,7 +1344,7 @@ static char *connect_to_host(char *host, int port, char **realhost) /* * Open socket. */ - s = sk_new(addr, port, ssh_receive); + s = sk_new(addr, port, 0, 1, &fn_table_ptr); if ( (err = sk_socket_error(s)) ) return err; @@ -1124,7 +1420,7 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) len = (hostkey.bytes > servkey.bytes ? hostkey.bytes : servkey.bytes); - rsabuf = malloc(len); + rsabuf = smalloc(len); if (!rsabuf) fatalbox("Out of memory"); @@ -1137,13 +1433,13 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) */ int len = rsastr_len(&hostkey); char fingerprint[100]; - char *keystr = malloc(len); + char *keystr = smalloc(len); if (!keystr) fatalbox("Out of memory"); rsastr_fmt(keystr, &hostkey); rsa_fingerprint(fingerprint, sizeof(fingerprint), &hostkey); verify_ssh_host_key(savedhost, savedport, "rsa", keystr, fingerprint); - free(keystr); + sfree(keystr); } for (i=0; i<32; i++) { @@ -1162,11 +1458,17 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) logevent("Encrypted session key"); - cipher_type = cfg.cipher == CIPHER_BLOWFISH ? SSH_CIPHER_BLOWFISH : - cfg.cipher == CIPHER_DES ? SSH_CIPHER_DES : - SSH_CIPHER_3DES; + 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("Selected cipher not supported, falling back to 3DES\r\n", 53); + c_write_str("Selected cipher not supported, falling back to 3DES\r\n"); cipher_type = SSH_CIPHER_3DES; } switch (cipher_type) { @@ -1185,7 +1487,7 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) logevent("Trying to enable encryption..."); - free(rsabuf); + sfree(rsabuf); cipher = cipher_type == SSH_CIPHER_BLOWFISH ? &ssh_blowfish_ssh1 : cipher_type == SSH_CIPHER_DES ? &ssh_des : @@ -1206,57 +1508,70 @@ 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) { - c_write("login as: ", 10); - ssh_send_ok = 1; - while (pos >= 0) { - crWaitUntil(!ispkt); - while (inlen--) switch (c = *in++) { - case 10: case 13: - username[pos] = 0; - pos = -1; - break; - case 8: case 127: - if (pos > 0) { - c_write("\b \b", 3); - pos--; - } - break; - case 21: case 27: - while (pos > 0) { - c_write("\b \b", 3); - pos--; - } - break; - case 3: case 4: - random_save_seed(); - exit(0); - break; - default: - if (((c >= ' ' && c <= '~') || - ((unsigned char)c >= 160)) && pos < 40) { - username[pos++] = c; - c_write(&c, 1); - } - break; - } - } - c_write("\r\n", 2); - username[strcspn(username, "\n\r")] = '\0'; - } else { - char stuff[200]; + if (ssh_get_line) { + if (!ssh_get_line("login as: ", + username, sizeof(username), FALSE)) { + /* + * get_line failed to get a username. + * Terminate. + */ + logevent("No username provided. Abandoning session."); + ssh_state = SSH_STATE_CLOSED; + crReturn(1); + } + } else { + c_write_str("login as: "); + ssh_send_ok = 1; + while (pos >= 0) { + crWaitUntil(!ispkt); + while (inlen--) switch (c = *in++) { + case 10: case 13: + username[pos] = 0; + pos = -1; + break; + case 8: case 127: + if (pos > 0) { + c_write_str("\b \b"); + pos--; + } + break; + case 21: case 27: + while (pos > 0) { + c_write_str("\b \b"); + pos--; + } + break; + case 3: case 4: + random_save_seed(); + exit(0); + break; + default: + if (((c >= ' ' && c <= '~') || + ((unsigned char)c >= 160)) && pos < 40) { + username[pos++] = c; + c_write(&c, 1); + } + break; + } + } + c_write_str("\r\n"); + username[strcspn(username, "\n\r")] = '\0'; + } + } else { strncpy(username, cfg.username, 99); username[99] = '\0'; - if ((flags & FLAG_VERBOSE) || (flags & FLAG_INTERACTIVE)) { - sprintf(stuff, "Sent username \"%s\".\r\n", username); - c_write(stuff, strlen(stuff)); - } } send_packet(SSH1_CMSG_USER, PKT_STR, username, PKT_END); { - char userlog[20+sizeof(username)]; + char userlog[22+sizeof(username)]; sprintf(userlog, "Sent username \"%s\"", username); logevent(userlog); + if (flags & FLAG_INTERACTIVE && + (!((flags & FLAG_STDERR) && (flags & FLAG_VERBOSE)))) { + strcat(userlog, "\r\n"); + c_write_str(userlog); + } } } @@ -1290,13 +1605,13 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) /* Request the keys held by the agent. */ PUT_32BIT(request, 1); - request[4] = SSH_AGENTC_REQUEST_RSA_IDENTITIES; + request[4] = SSH1_AGENTC_REQUEST_RSA_IDENTITIES; agent_query(request, 5, &r, &responselen); response = (unsigned char *)r; if (response) { p = response + 5; nkeys = GET_32BIT(p); p += 4; - { char buf[64]; sprintf(buf, "Pageant has %d keys", nkeys); + { char buf[64]; sprintf(buf, "Pageant has %d SSH1 keys", nkeys); logevent(buf); } for (i = 0; i < nkeys; i++) { static struct RSAKey key; @@ -1329,10 +1644,10 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) len += ssh1_bignum_length(challenge); len += 16; /* session id */ len += 4; /* response format */ - agentreq = malloc(4 + len); + agentreq = smalloc(4 + len); PUT_32BIT(agentreq, len); q = agentreq + 4; - *q++ = SSH_AGENTC_RSA_CHALLENGE; + *q++ = SSH1_AGENTC_RSA_CHALLENGE; PUT_32BIT(q, ssh1_bignum_bitcount(key.modulus)); q += 4; q += ssh1_write_bignum(q, key.exponent); @@ -1341,28 +1656,27 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) memcpy(q, session_id, 16); q += 16; PUT_32BIT(q, 1); /* response format */ agent_query(agentreq, len+4, &ret, &retlen); - free(agentreq); + sfree(agentreq); if (ret) { - if (ret[4] == SSH_AGENT_RSA_RESPONSE) { + if (ret[4] == SSH1_AGENT_RSA_RESPONSE) { logevent("Sending Pageant's response"); send_packet(SSH1_CMSG_AUTH_RSA_RESPONSE, PKT_DATA, ret+5, 16, PKT_END); - free(ret); + sfree(ret); crWaitUntil(ispkt); if (pktin.type == SSH1_SMSG_SUCCESS) { logevent("Pageant's response accepted"); if (flags & FLAG_VERBOSE) { - c_write("Authenticated using RSA key \"", - 29); + c_write_str("Authenticated using RSA key \""); c_write(commentp, commentlen); - c_write("\" from agent\r\n", 14); + c_write_str("\" from agent\r\n"); } authed = TRUE; } else logevent("Pageant's response not accepted"); } else { logevent("Pageant failed to answer challenge"); - free(ret); + sfree(ret); } } else { logevent("No reply received from Pageant"); @@ -1391,7 +1705,7 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) if (pktin.type != SSH1_SMSG_AUTH_TIS_CHALLENGE) { logevent("TIS authentication declined"); if (flags & FLAG_INTERACTIVE) - c_write("TIS authentication refused.\r\n", 29); + c_write_str("TIS authentication refused.\r\n"); } else { int challengelen = ((pktin.body[0] << 24) | (pktin.body[1] << 16) | @@ -1413,7 +1727,7 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) crWaitUntil(ispkt); if (pktin.type != SSH1_SMSG_AUTH_CCARD_CHALLENGE) { logevent("CryptoCard authentication declined"); - c_write("CryptoCard authentication refused.\r\n", 29); + c_write_str("CryptoCard authentication refused.\r\n"); } else { int challengelen = ((pktin.body[0] << 24) | (pktin.body[1] << 16) | @@ -1435,30 +1749,29 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) if (pwpkt_type == SSH1_CMSG_AUTH_RSA) { char *comment = NULL; if (flags & FLAG_VERBOSE) - c_write("Trying public key authentication.\r\n", 35); + c_write_str("Trying public key authentication.\r\n"); if (!rsakey_encrypted(cfg.keyfile, &comment)) { if (flags & FLAG_VERBOSE) - c_write("No passphrase required.\r\n", 25); + c_write_str("No passphrase required.\r\n"); goto tryauth; } sprintf(prompt, "Passphrase for key \"%.100s\": ", comment); - free(comment); + sfree(comment); } - if (ssh_get_password) { - if (!ssh_get_password(prompt, password, sizeof(password))) { + if (ssh_get_line) { + if (!ssh_get_line(prompt, password, sizeof(password), TRUE)) { /* - * get_password failed to get a password (for - * example because one was supplied on the command - * line which has already failed to work). - * Terminate. + * get_line failed to get a password (for example + * because one was supplied on the command line + * which has already failed to work). Terminate. */ logevent("No more passwords to try"); ssh_state = SSH_STATE_CLOSED; crReturn(1); } } else { - c_write(prompt, strlen(prompt)); + c_write_str(prompt); pos = 0; ssh_send_ok = 1; while (pos >= 0) { @@ -1486,7 +1799,7 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) break; } } - c_write("\r\n", 2); + c_write_str("\r\n"); } tryauth: @@ -1501,15 +1814,15 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) static unsigned char buffer[32]; tried_publickey = 1; - i = loadrsakey(cfg.keyfile, &pubkey, NULL, password); + i = loadrsakey(cfg.keyfile, &pubkey, password); if (i == 0) { - c_write("Couldn't load public key from ", 30); - c_write(cfg.keyfile, strlen(cfg.keyfile)); - c_write(".\r\n", 3); + c_write_str("Couldn't load public key from "); + c_write_str(cfg.keyfile); + c_write_str(".\r\n"); continue; /* go and try password */ } if (i == -1) { - c_write("Wrong passphrase.\r\n", 19); + c_write_str("Wrong passphrase.\r\n"); tried_publickey = 0; continue; /* try again */ } @@ -1522,7 +1835,7 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) crWaitUntil(ispkt); if (pktin.type == SSH1_SMSG_FAILURE) { - c_write("Server refused our public key.\r\n", 32); + c_write_str("Server refused our public key.\r\n"); continue; /* go and try password */ } if (pktin.type != SSH1_SMSG_AUTH_RSA_CHALLENGE) { @@ -1533,9 +1846,8 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) response = rsadecrypt(challenge, &pubkey); freebn(pubkey.private_exponent); /* burn the evidence */ - for (i = 0; i < 32; i += 2) { - buffer[i] = response[16-i/2] >> 8; - buffer[i+1] = response[16-i/2] & 0xFF; + for (i = 0; i < 32; i++) { + buffer[i] = bignum_byte(response, 31-i); } MD5Init(&md5c); @@ -1549,8 +1861,7 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) crWaitUntil(ispkt); if (pktin.type == SSH1_SMSG_FAILURE) { if (flags & FLAG_VERBOSE) - c_write("Failed to authenticate with our public key.\r\n", - 45); + c_write_str("Failed to authenticate with our public key.\r\n"); continue; /* go and try password */ } else if (pktin.type != SSH1_SMSG_SUCCESS) { bombout(("Bizarre response to RSA authentication response")); @@ -1559,14 +1870,101 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) break; /* we're through! */ } else { - send_packet(pwpkt_type, PKT_STR, password, PKT_END); + if (pwpkt_type == SSH1_CMSG_AUTH_PASSWORD) { + /* + * Defence against traffic analysis: we send a + * whole bunch of packets containing strings of + * different lengths. One of these strings is the + * password, in a SSH1_CMSG_AUTH_PASSWORD packet. + * The others are all random data in + * SSH1_MSG_IGNORE packets. This way a passive + * listener can't tell which is the password, and + * hence can't deduce the password length. + * + * Anybody with a password length greater than 16 + * bytes is going to have enough entropy in their + * password that a listener won't find it _that_ + * much help to know how long it is. So what we'll + * do is: + * + * - if password length < 16, we send 15 packets + * containing string lengths 1 through 15 + * + * - otherwise, we let N be the nearest multiple + * of 8 below the password length, and send 8 + * packets containing string lengths N through + * N+7. This won't obscure the order of + * magnitude of the password length, but it will + * introduce a bit of extra uncertainty. + * + * A few servers (the old 1.2.18 through 1.2.22) + * can't deal with SSH1_MSG_IGNORE. For these + * servers, we need an alternative defence. We make + * use of the fact that the password is interpreted + * as a C string: so we can append a NUL, then some + * random data. + */ + 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 { + int bottom, top, pwlen, i; + char *randomstr; + + pwlen = strlen(password); + if (pwlen < 16) { + bottom = 0; /* zero length passwords are OK! :-) */ + top = 15; + } else { + bottom = pwlen &~ 7; + top = bottom + 7; + } + + assert(pwlen >= bottom && pwlen <= top); + + randomstr = smalloc(top+1); + + for (i = bottom; i <= top; i++) { + if (i == pwlen) + defer_packet(pwpkt_type, PKT_STR, password, PKT_END); + else { + for (j = 0; j < i; j++) { + do { + randomstr[j] = random_byte(); + } while (randomstr[j] == '\0'); + } + randomstr[i] = '\0'; + defer_packet(SSH1_MSG_IGNORE, + PKT_STR, randomstr, PKT_END); + } + } + ssh_pkt_defersend(); + } + } else { + send_packet(pwpkt_type, PKT_STR, password, PKT_END); + } } logevent("Sent password"); memset(password, 0, strlen(password)); crWaitUntil(ispkt); if (pktin.type == SSH1_SMSG_FAILURE) { if (flags & FLAG_VERBOSE) - c_write("Access denied\r\n", 15); + c_write_str("Access denied\r\n"); logevent("Authentication refused"); } else if (pktin.type == SSH1_MSG_DISCONNECT) { logevent("Received disconnect request"); @@ -1583,6 +1981,36 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) crFinish(1); } +void sshfwd_close(struct ssh_channel *c) { + if (c) { + 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("X11 connection terminated"); + } + } +} + +void 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); + } else { + ssh2_add_channel_data(c, buf, len); + ssh2_try_send(c); + } +} + static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) { crBegin; @@ -1603,8 +2031,30 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) { crReturnV; } else if (pktin.type == SSH1_SMSG_FAILURE) { logevent("Agent forwarding refused"); - } else + } else { logevent("Agent forwarding enabled"); + ssh_agentfwd_enabled = TRUE; + } + } + + if (cfg.x11_forward) { + 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); + do { crReturnV; } while (!ispkt); + if (pktin.type != SSH1_SMSG_SUCCESS && pktin.type != SSH1_SMSG_FAILURE) { + bombout(("Protocol confusion")); + crReturnV; + } else if (pktin.type == SSH1_SMSG_FAILURE) { + logevent("X11 forwarding refused"); + } else { + logevent("X11 forwarding enabled"); + ssh_X11_fwd_enabled = TRUE; + } } if (!cfg.nopty) { @@ -1620,9 +2070,27 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) { bombout(("Protocol confusion")); crReturnV; } else if (pktin.type == SSH1_SMSG_FAILURE) { - c_write("Server refused to allocate pty\r\n", 32); + c_write_str("Server refused to allocate pty\r\n"); + ssh_editing = ssh_echoing = 1; } logevent("Allocated pty"); + } else { + ssh_editing = ssh_echoing = 1; + } + + if (cfg.compression) { + send_packet(SSH1_CMSG_REQUEST_COMPRESSION, PKT_INT, 6, PKT_END); + do { crReturnV; } while (!ispkt); + if (pktin.type != SSH1_SMSG_SUCCESS && pktin.type != SSH1_SMSG_FAILURE) { + bombout(("Protocol confusion")); + crReturnV; + } else if (pktin.type == SSH1_SMSG_FAILURE) { + c_write_str("Server refused to compress\r\n"); + } + logevent("Started compression"); + ssh1_compressing = TRUE; + zlib_compress_init(); + zlib_decompress_init(); } if (*cfg.remote_cmd) @@ -1634,10 +2102,12 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) { ssh_state = SSH_STATE_SESSION; if (size_needed) ssh_size(); + if (eof_needed) + ssh_special(TS_EOF); + ldisc_send(NULL, 0); /* cause ldisc to notice changes */ ssh_send_ok = 1; ssh_channels = newtree234(ssh_channelcmp); - begin_session(); while (1) { crReturnV; if (ispkt) { @@ -1650,29 +2120,79 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) { ssh_state = SSH_STATE_CLOSED; logevent("Received disconnect request"); crReturnV; + } else if (pktin.type == SSH1_SMSG_X11_OPEN) { + /* Remote side is trying to open a channel to talk to our + * X-Server. Give them back a local channel number. */ + unsigned i; + struct ssh_channel *c, *d; + enum234 e; + + logevent("Received X11 connect request"); + /* Refuse if X11 forwarding is disabled. */ + if (!ssh_X11_fwd_enabled) { + send_packet(SSH1_MSG_CHANNEL_OPEN_FAILURE, + PKT_INT, GET_32BIT(pktin.body), + PKT_END); + logevent("Rejected X11 connect request"); + } else { + c = smalloc(sizeof(struct ssh_channel)); + + if ( x11_init(&c->u.x11.s, cfg.x11_display, c) != NULL ) { + logevent("opening X11 forward connection failed"); + sfree(c); + send_packet(SSH1_MSG_CHANNEL_OPEN_FAILURE, + PKT_INT, GET_32BIT(pktin.body), + PKT_END); + } else { + logevent("opening X11 forward connection succeeded"); + for (i=1, d = first234(ssh_channels, &e); d; d = next234(&e)) { + if (d->localid > i) + break; /* found a free number */ + i = d->localid + 1; + } + c->remoteid = GET_32BIT(pktin.body); + c->localid = i; + c->closes = 0; + c->type = CHAN_X11; /* identify channel type */ + add234(ssh_channels, c); + send_packet(SSH1_MSG_CHANNEL_OPEN_CONFIRMATION, + PKT_INT, c->remoteid, PKT_INT, c->localid, + PKT_END); + logevent("Opened X11 forward channel"); + } + } } else if (pktin.type == SSH1_SMSG_AGENT_OPEN) { /* Remote side is trying to open a channel to talk to our * agent. Give them back a local channel number. */ - unsigned i = 1; + unsigned i; struct ssh_channel *c; enum234 e; - for (c = first234(ssh_channels, &e); c; c = next234(&e)) { - if (c->localid > i) - break; /* found a free number */ - i = c->localid + 1; - } - c = malloc(sizeof(struct ssh_channel)); - c->remoteid = GET_32BIT(pktin.body); - c->localid = i; - c->closes = 0; - c->type = SSH1_SMSG_AGENT_OPEN; /* identify channel type */ - c->u.a.lensofar = 0; - add234(ssh_channels, c); - send_packet(SSH1_MSG_CHANNEL_OPEN_CONFIRMATION, - PKT_INT, c->remoteid, PKT_INT, c->localid, - PKT_END); - } else if (pktin.type == SSH1_MSG_CHANNEL_CLOSE || - pktin.type == SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION) { + + /* Refuse if agent forwarding is disabled. */ + if (!ssh_agentfwd_enabled) { + send_packet(SSH1_MSG_CHANNEL_OPEN_FAILURE, + PKT_INT, GET_32BIT(pktin.body), + PKT_END); + } else { + i = 1; + for (c = first234(ssh_channels, &e); c; c = next234(&e)) { + if (c->localid > i) + break; /* found a free number */ + i = c->localid + 1; + } + c = smalloc(sizeof(struct ssh_channel)); + c->remoteid = GET_32BIT(pktin.body); + c->localid = i; + c->closes = 0; + c->type = CHAN_AGENT; /* identify channel type */ + c->u.a.lensofar = 0; + add234(ssh_channels, c); + send_packet(SSH1_MSG_CHANNEL_OPEN_CONFIRMATION, + PKT_INT, c->remoteid, PKT_INT, c->localid, + PKT_END); + } + } else if (pktin.type == SSH1_MSG_CHANNEL_CLOSE || + pktin.type == SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION) { /* Remote side closes a channel. */ unsigned i = GET_32BIT(pktin.body); struct ssh_channel *c; @@ -1681,10 +2201,16 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) { int closetype; closetype = (pktin.type == SSH1_MSG_CHANNEL_CLOSE ? 1 : 2); 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); + x11_close(c->u.x11.s); + c->u.x11.s = NULL; + } c->closes |= closetype; if (c->closes == 3) { del234(ssh_channels, c); - free(c); + sfree(c); } } } else if (pktin.type == SSH1_MSG_CHANNEL_DATA) { @@ -1696,7 +2222,10 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) { c = find234(ssh_channels, &i, ssh_channelfind); if (c) { switch(c->type) { - case SSH1_SMSG_AGENT_OPEN: + case CHAN_X11: + x11_send(c->u.x11.s, p, len); + break; + case CHAN_AGENT: /* Data for an agent message. Buffer it. */ while (len > 0) { if (c->u.a.lensofar < 4) { @@ -1706,7 +2235,7 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) { } if (c->u.a.lensofar == 4) { c->u.a.totallen = 4 + GET_32BIT(c->u.a.msglen); - c->u.a.message = malloc(c->u.a.totallen); + c->u.a.message = smalloc(c->u.a.totallen); memcpy(c->u.a.message, c->u.a.msglen, 4); } if (c->u.a.lensofar >= 4 && len > 0) { @@ -1732,8 +2261,8 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) { PKT_DATA, sentreply, replylen, PKT_END); if (reply) - free(reply); - free(c->u.a.message); + sfree(reply); + sfree(c->u.a.message); c->u.a.lensofar = 0; } } @@ -1795,14 +2324,14 @@ static int in_commasep_string(char *needle, char *haystack, int haylen) { /* * SSH2 key creation method. */ -static void ssh2_mkkey(Bignum K, char *H, char chr, char *keyspace) { +static void ssh2_mkkey(Bignum K, char *H, char *sessid, char chr, char *keyspace) { SHA_State s; /* First 20 bytes. */ SHA_Init(&s); sha_mpint(&s, K); SHA_Bytes(&s, H, 20); SHA_Bytes(&s, &chr, 1); - SHA_Bytes(&s, H, 20); + SHA_Bytes(&s, sessid, 20); SHA_Final(&s, keyspace); /* Next 20 bytes. */ SHA_Init(&s); @@ -1817,45 +2346,56 @@ static void ssh2_mkkey(Bignum K, char *H, char chr, char *keyspace) { */ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt) { - static int i, len; + static int i, j, len, nbits, pbits; static char *str; - static Bignum e, f, K; + static Bignum p, g, e, f, K; + static int kex_init_value, kex_reply_value; static const struct ssh_mac **maclist; static int nmacs; - static const struct ssh_cipher *cscipher_tobe = NULL; - static const struct ssh_cipher *sccipher_tobe = NULL; + static const struct ssh2_cipher *cscipher_tobe = NULL; + static const struct ssh2_cipher *sccipher_tobe = NULL; static const struct ssh_mac *csmac_tobe = NULL; static const struct ssh_mac *scmac_tobe = NULL; static const struct ssh_compress *cscomp_tobe = NULL; static const struct ssh_compress *sccomp_tobe = NULL; static char *hostkeydata, *sigdata, *keystr, *fingerprint; static int hostkeylen, siglen; + static void *hkey; /* actual host key */ static unsigned char exchange_hash[20]; static unsigned char keyspace[40]; - static const struct ssh_cipher *preferred_cipher; + static const struct ssh2_ciphers *preferred_cipher; + static const struct ssh_compress *preferred_comp; + static int first_kex; crBegin; random_init(); + first_kex = 1; /* - * Set up the preferred cipher. + * Set up the preferred cipher and compression. */ if (cfg.cipher == CIPHER_BLOWFISH) { - preferred_cipher = &ssh_blowfish_ssh2; + preferred_cipher = &ssh2_blowfish; } else if (cfg.cipher == CIPHER_DES) { logevent("Single DES not supported in SSH2; using 3DES"); - preferred_cipher = &ssh_3des_ssh2; + preferred_cipher = &ssh2_3des; } else if (cfg.cipher == CIPHER_3DES) { - preferred_cipher = &ssh_3des_ssh2; + 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 = &ssh_3des_ssh2; + preferred_cipher = &ssh2_3des; } + if (cfg.compression) + preferred_comp = &ssh_zlib; + else + preferred_comp = &ssh_comp_none; /* * Be prepared to work around the buggy MAC problem. */ - if (cfg.buggymac) + if (cfg.buggymac || (ssh_remote_bugs & BUG_SSH2_HMAC)) maclist = buggymacs, nmacs = lenof(buggymacs); else maclist = macs, nmacs = lenof(macs); @@ -1884,18 +2424,22 @@ 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 ssh_cipher *c = i==0 ? preferred_cipher : ciphers[i-1]; - ssh2_pkt_addstring_str(c->name); - if (i < lenof(ciphers)) - ssh2_pkt_addstring_str(","); + const struct ssh2_ciphers *c = i==0 ? preferred_cipher : ciphers[i-1]; + for (j = 0; j < c->nciphers; j++) { + ssh2_pkt_addstring_str(c->list[j]->name); + if (i < lenof(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 ssh_cipher *c = i==0 ? preferred_cipher : ciphers[i-1]; - ssh2_pkt_addstring_str(c->name); - if (i < lenof(ciphers)) - ssh2_pkt_addstring_str(","); + const struct ssh2_ciphers *c = i==0 ? preferred_cipher : ciphers[i-1]; + for (j = 0; j < c->nciphers; j++) { + ssh2_pkt_addstring_str(c->list[j]->name); + if (i < lenof(ciphers) || j < c->nciphers-1) + ssh2_pkt_addstring_str(","); + } } /* List client->server MAC algorithms. */ ssh2_pkt_addstring_start(); @@ -1913,16 +2457,18 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt) } /* List client->server compression algorithms. */ ssh2_pkt_addstring_start(); - for (i = 0; i < lenof(compressions); i++) { - ssh2_pkt_addstring_str(compressions[i]->name); - if (i < lenof(compressions)-1) + for (i = 0; i < lenof(compressions)+1; i++) { + const struct ssh_compress *c = i==0 ? preferred_comp : compressions[i-1]; + ssh2_pkt_addstring_str(c->name); + if (i < lenof(compressions)) ssh2_pkt_addstring_str(","); } /* List server->client compression algorithms. */ ssh2_pkt_addstring_start(); - for (i = 0; i < lenof(compressions); i++) { - ssh2_pkt_addstring_str(compressions[i]->name); - if (i < lenof(compressions)-1) + for (i = 0; i < lenof(compressions)+1; i++) { + const struct ssh_compress *c = i==0 ? preferred_comp : compressions[i-1]; + ssh2_pkt_addstring_str(c->name); + if (i < lenof(compressions)) ssh2_pkt_addstring_str(","); } /* List client->server languages. Empty list. */ @@ -1933,7 +2479,10 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt) ssh2_pkt_addbool(FALSE); /* Reserved. */ ssh2_pkt_adduint32(0); + + exhash = exhashbase; sha_string(&exhash, pktout.data+5, pktout.length-5); + ssh2_pkt_send(); if (!ispkt) crWaitUntil(ispkt); @@ -1966,19 +2515,27 @@ 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 ssh_cipher *c = i==0 ? preferred_cipher : ciphers[i-1]; - if (in_commasep_string(c->name, str, len)) { - cscipher_tobe = c; - break; + 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; + } } + if (cscipher_tobe) + break; } ssh2_pkt_getstring(&str, &len); /* server->client cipher */ for (i = 0; i < lenof(ciphers)+1; i++) { - const struct ssh_cipher *c = i==0 ? preferred_cipher : ciphers[i-1]; - if (in_commasep_string(c->name, str, len)) { - sccipher_tobe = c; - break; + 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; + } } + if (sccipher_tobe) + break; } ssh2_pkt_getstring(&str, &len); /* client->server mac */ for (i = 0; i < nmacs; i++) { @@ -1995,40 +2552,81 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt) } } ssh2_pkt_getstring(&str, &len); /* client->server compression */ - for (i = 0; i < lenof(compressions); i++) { - if (in_commasep_string(compressions[i]->name, str, len)) { - cscomp_tobe = compressions[i]; + for (i = 0; i < lenof(compressions)+1; i++) { + const struct ssh_compress *c = i==0 ? preferred_comp : compressions[i-1]; + if (in_commasep_string(c->name, str, len)) { + cscomp_tobe = c; break; } } ssh2_pkt_getstring(&str, &len); /* server->client compression */ - for (i = 0; i < lenof(compressions); i++) { - if (in_commasep_string(compressions[i]->name, str, len)) { - sccomp_tobe = compressions[i]; + for (i = 0; i < lenof(compressions)+1; i++) { + const struct ssh_compress *c = i==0 ? preferred_comp : compressions[i-1]; + if (in_commasep_string(c->name, str, len)) { + sccomp_tobe = c; break; } } /* - * Currently we only support Diffie-Hellman and DSS, so let's - * bomb out if those aren't selected. + * Work out the number of bits of key we will need from the key + * exchange. We start with the maximum key length of either + * cipher... */ - if (kex != &ssh_diffiehellman || hostkey != &ssh_dss) { - bombout(("internal fault: chaos in SSH 2 transport layer")); - crReturn(0); + { + int csbits, scbits; + + csbits = cscipher_tobe->keylen; + scbits = sccipher_tobe->keylen; + nbits = (csbits > scbits ? csbits : scbits); + } + /* The keys only have 160-bit entropy, since they're based on + * a SHA-1 hash. So cap the key size at 160 bits. */ + if (nbits > 160) nbits = 160; + + /* + * If we're doing Diffie-Hellman group exchange, start by + * requesting a group. + */ + if (kex == &ssh_diffiehellman_gex) { + logevent("Doing Diffie-Hellman group exchange"); + /* + * Work out how big a DH group we will need to allow that + * much data. + */ + pbits = 512 << ((nbits-1) / 64); + ssh2_pkt_init(SSH2_MSG_KEX_DH_GEX_REQUEST); + ssh2_pkt_adduint32(pbits); + ssh2_pkt_send(); + + crWaitUntil(ispkt); + if (pktin.type != SSH2_MSG_KEX_DH_GEX_GROUP) { + bombout(("expected key exchange group packet from server")); + crReturn(0); + } + p = ssh2_pkt_getmp(); + g = ssh2_pkt_getmp(); + dh_setup_group(p, g); + kex_init_value = SSH2_MSG_KEX_DH_GEX_INIT; + kex_reply_value = SSH2_MSG_KEX_DH_GEX_REPLY; + } else { + dh_setup_group1(); + kex_init_value = SSH2_MSG_KEXDH_INIT; + kex_reply_value = SSH2_MSG_KEXDH_REPLY; } + logevent("Doing Diffie-Hellman key exchange"); /* - * Now we begin the fun. Generate and send e for Diffie-Hellman. + * Now generate and send e for Diffie-Hellman. */ - e = dh_create_e(); - ssh2_pkt_init(SSH2_MSG_KEXDH_INIT); + e = dh_create_e(nbits*2); + ssh2_pkt_init(kex_init_value); ssh2_pkt_addmp(e); ssh2_pkt_send(); crWaitUntil(ispkt); - if (pktin.type != SSH2_MSG_KEXDH_REPLY) { - bombout(("expected key exchange packet from server")); + if (pktin.type != kex_reply_value) { + bombout(("expected key exchange reply packet from server")); crReturn(0); } ssh2_pkt_getstring(&hostkeydata, &hostkeylen); @@ -2038,11 +2636,18 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt) K = dh_find_K(f); sha_string(&exhash, hostkeydata, hostkeylen); + if (kex == &ssh_diffiehellman_gex) { + sha_uint32(&exhash, pbits); + sha_mpint(&exhash, p); + sha_mpint(&exhash, g); + } sha_mpint(&exhash, e); sha_mpint(&exhash, f); sha_mpint(&exhash, K); SHA_Final(&exhash, exchange_hash); + dh_cleanup(); + #if 0 debug(("Exchange hash is:\r\n")); for (i = 0; i < 20; i++) @@ -2050,8 +2655,8 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt) debug(("\r\n")); #endif - hostkey->setkey(hostkeydata, hostkeylen); - if (!hostkey->verifysig(sigdata, siglen, exchange_hash, 20)) { + hkey = hostkey->newkey(hostkeydata, hostkeylen); + if (!hostkey->verifysig(hkey, sigdata, siglen, exchange_hash, 20)) { bombout(("Server failed host key check")); crReturn(0); } @@ -2069,14 +2674,17 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt) * Authenticate remote host: verify host key. (We've already * checked the signature of the exchange hash.) */ - keystr = hostkey->fmtkey(); - fingerprint = hostkey->fingerprint(); + keystr = hostkey->fmtkey(hkey); + fingerprint = hostkey->fingerprint(hkey); verify_ssh_host_key(savedhost, savedport, hostkey->keytype, keystr, fingerprint); - logevent("Host key fingerprint is:"); - logevent(fingerprint); - free(fingerprint); - free(keystr); + if (first_kex) { /* don't bother logging this in rekeys */ + logevent("Host key fingerprint is:"); + logevent(fingerprint); + } + sfree(fingerprint); + sfree(keystr); + hostkey->freekey(hkey); /* * Send SSH2_MSG_NEWKEYS. @@ -2093,15 +2701,39 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt) scmac = scmac_tobe; cscomp = cscomp_tobe; sccomp = sccomp_tobe; + cscomp->compress_init(); + sccomp->decompress_init(); + /* + * Set IVs after keys. Here we use the exchange hash from the + * _first_ key exchange. + */ + if (first_kex) + memcpy(ssh2_session_id, exchange_hash, sizeof(exchange_hash)); + ssh2_mkkey(K, exchange_hash, ssh2_session_id, 'C', keyspace); + cscipher->setcskey(keyspace); + ssh2_mkkey(K, exchange_hash, ssh2_session_id, 'D', keyspace); + sccipher->setsckey(keyspace); + ssh2_mkkey(K, exchange_hash, ssh2_session_id, 'A', keyspace); + cscipher->setcsiv(keyspace); + ssh2_mkkey(K, exchange_hash, ssh2_session_id, 'B', keyspace); + sccipher->setsciv(keyspace); + ssh2_mkkey(K, exchange_hash, ssh2_session_id, 'E', keyspace); + csmac->setcskey(keyspace); + ssh2_mkkey(K, exchange_hash, ssh2_session_id, 'F', keyspace); + scmac->setsckey(keyspace); + /* - * Set IVs after keys. + * If this is the first key exchange phase, we must pass the + * SSH2_MSG_NEWKEYS packet to the next layer, not because it + * wants to see it but because it will need time to initialise + * itself before it sees an actual packet. In subsequent key + * exchange phases, we don't pass SSH2_MSG_NEWKEYS on, because + * it would only confuse the layer above. */ - ssh2_mkkey(K, exchange_hash, 'C', keyspace); cscipher->setcskey(keyspace); - ssh2_mkkey(K, exchange_hash, 'D', keyspace); cscipher->setsckey(keyspace); - ssh2_mkkey(K, exchange_hash, 'A', keyspace); cscipher->setcsiv(keyspace); - ssh2_mkkey(K, exchange_hash, 'B', keyspace); sccipher->setsciv(keyspace); - ssh2_mkkey(K, exchange_hash, 'E', keyspace); csmac->setcskey(keyspace); - ssh2_mkkey(K, exchange_hash, 'F', keyspace); scmac->setsckey(keyspace); + if (!first_kex) { + crReturn(0); + } + first_kex = 0; /* * Now we're encrypting. Begin returning 1 to the protocol main @@ -2109,21 +2741,77 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt) * transport. If we ever see a KEXINIT, we must go back to the * start. */ - do { + while (!(ispkt && pktin.type == SSH2_MSG_KEXINIT)) { crReturn(1); - } while (!(ispkt && pktin.type == SSH2_MSG_KEXINIT)); + } + logevent("Server initiated key re-exchange"); goto begin_key_exchange; crFinish(1); } /* + * Add data to an SSH2 channel output buffer. + */ +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; +} + +/* + * Attempt to send data on an SSH2 channel. + */ +static void 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; + 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_send(); + c->v2.outbuflen -= len; + memmove(c->v2.outbuffer, c->v2.outbuffer+len, + c->v2.outbuflen); + c->v2.remwindow -= len; + } +} + +/* * Handle the SSH2 userauth and connection layers. */ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) { static unsigned long remote_winsize; static unsigned long remote_maxpkt; + static enum { + AUTH_INVALID, AUTH_PUBLICKEY_AGENT, AUTH_PUBLICKEY_FILE, AUTH_PASSWORD + } method; + static enum { + AUTH_TYPE_NONE, + AUTH_TYPE_PUBLICKEY, + AUTH_TYPE_PUBLICKEY_OFFER_LOUD, + AUTH_TYPE_PUBLICKEY_OFFER_QUIET, + AUTH_TYPE_PASSWORD + } type; + static int gotit, need_pw, can_pubkey, can_passwd; + static int tried_pubkey_config, tried_agent; + static int we_are_in; + static char username[100]; + static char pwprompt[200]; + static char password[100]; crBegin; @@ -2140,128 +2828,550 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) } /* - * FIXME: currently we support only password authentication. - * (This places us technically in violation of the SSH2 spec. - * We must fix this.) + * We repeat this whole loop, including the username prompt, + * until we manage a successful authentication. If the user + * types the wrong _password_, they are sent back to the + * beginning to try another username. (If they specify a + * username in the config, they are never asked, even if they + * do give a wrong password.) + * + * I think this best serves the needs of + * + * - the people who have no configuration, no keys, and just + * want to try repeated (username,password) pairs until they + * type both correctly + * + * - people who have keys and configuration but occasionally + * need to fall back to passwords + * + * - people with a key held in Pageant, who might not have + * logged in to a particular machine before; so they want to + * type a username, and then _either_ their key will be + * accepted, _or_ they will type a password. If they mistype + * the username they will want to be able to get back and + * retype it! */ - while (1) { - /* - * Get a username and a password. - */ - static char username[100]; - static char password[100]; - static int pos = 0; + do { + static int pos; static char c; + /* + * Get a username. + */ + pos = 0; if ((flags & FLAG_INTERACTIVE) && !*cfg.username) { - c_write("login as: ", 10); - ssh_send_ok = 1; - while (pos >= 0) { - crWaitUntilV(!ispkt); - while (inlen--) switch (c = *in++) { - case 10: case 13: - username[pos] = 0; - pos = -1; - break; - case 8: case 127: - if (pos > 0) { - c_write("\b \b", 3); - pos--; - } - break; - case 21: case 27: - while (pos > 0) { - c_write("\b \b", 3); - pos--; - } - break; - case 3: case 4: - random_save_seed(); - exit(0); - break; - default: - if (((c >= ' ' && c <= '~') || - ((unsigned char)c >= 160)) && pos < 40) { - username[pos++] = c; - c_write(&c, 1); - } - break; - } - } - c_write("\r\n", 2); + if (ssh_get_line) { + if (!ssh_get_line("login as: ", + username, sizeof(username), FALSE)) { + /* + * get_line failed to get a username. + * Terminate. + */ + logevent("No username provided. Abandoning session."); + ssh_state = SSH_STATE_CLOSED; + crReturn(1); + } + } else { + c_write_str("login as: "); + ssh_send_ok = 1; + while (pos >= 0) { + crWaitUntilV(!ispkt); + while (inlen--) switch (c = *in++) { + case 10: case 13: + username[pos] = 0; + pos = -1; + break; + case 8: case 127: + if (pos > 0) { + c_write_str("\b \b"); + pos--; + } + break; + case 21: case 27: + while (pos > 0) { + c_write_str("\b \b"); + pos--; + } + break; + case 3: case 4: + random_save_seed(); + exit(0); + break; + default: + if (((c >= ' ' && c <= '~') || + ((unsigned char)c >= 160)) && pos < 40) { + username[pos++] = c; + c_write(&c, 1); + } + break; + } + } + } + c_write_str("\r\n"); username[strcspn(username, "\n\r")] = '\0'; } else { char stuff[200]; strncpy(username, cfg.username, 99); username[99] = '\0'; - if ((flags & FLAG_VERBOSE) || (flags & FLAG_INTERACTIVE)) { + if ((flags & FLAG_VERBOSE) || (flags & FLAG_INTERACTIVE)) { sprintf(stuff, "Using username \"%s\".\r\n", username); - c_write(stuff, strlen(stuff)); + c_write_str(stuff); } } - if (ssh_get_password) { - char prompt[200]; - sprintf(prompt, "%.90s@%.90s's password: ", username, savedhost); - if (!ssh_get_password(prompt, password, sizeof(password))) { - /* - * get_password failed to get a password (for - * example because one was supplied on the command - * line which has already failed to work). - * Terminate. - */ - logevent("No more passwords to try"); - ssh_state = SSH_STATE_CLOSED; - crReturnV; - } - } else { - c_write("password: ", 10); - ssh_send_ok = 1; + /* + * Send an authentication request using method "none": (a) + * just in case it succeeds, and (b) so that we know what + * authentication methods we can usefully try next. + */ + ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST); + ssh2_pkt_addstring(username); + ssh2_pkt_addstring("ssh-connection"); /* service requested */ + ssh2_pkt_addstring("none"); /* method */ + ssh2_pkt_send(); + type = AUTH_TYPE_NONE; + gotit = FALSE; + we_are_in = FALSE; + + tried_pubkey_config = FALSE; + tried_agent = FALSE; + + while (1) { + /* + * Wait for the result of the last authentication request. + */ + if (!gotit) + crWaitUntilV(ispkt); + while (pktin.type == SSH2_MSG_USERAUTH_BANNER) { + /* FIXME: should support this */ + crWaitUntilV(ispkt); + } + if (pktin.type == SSH2_MSG_USERAUTH_SUCCESS) { + logevent("Access granted"); + we_are_in = TRUE; + break; + } - pos = 0; - while (pos >= 0) { - crWaitUntilV(!ispkt); - while (inlen--) switch (c = *in++) { - case 10: case 13: - password[pos] = 0; - pos = -1; - break; - case 8: case 127: - if (pos > 0) - pos--; - break; - case 21: case 27: - pos = 0; - break; - case 3: case 4: - random_save_seed(); - exit(0); - break; - default: - if (((c >= ' ' && c <= '~') || - ((unsigned char)c >= 160)) && pos < 40) - password[pos++] = c; - break; - } - } - c_write("\r\n", 2); - } + if (pktin.type != SSH2_MSG_USERAUTH_FAILURE) { + bombout(("Strange packet received during authentication: type %d", + pktin.type)); + } - ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST); - ssh2_pkt_addstring(username); - ssh2_pkt_addstring("ssh-connection"); /* service requested */ - ssh2_pkt_addstring("password"); - ssh2_pkt_addbool(FALSE); - ssh2_pkt_addstring(password); - ssh2_pkt_send(); + gotit = FALSE; + + /* + * OK, we're now sitting on a USERAUTH_FAILURE message, so + * we can look at the string in it and know what we can + * helpfully try next. + */ + { + char *methods; + int methlen; + ssh2_pkt_getstring(&methods, &methlen); + if (!ssh2_pkt_getbool()) { + /* + * We have received an unequivocal Access + * Denied. This can translate to a variety of + * messages: + * + * - if we'd just tried "none" authentication, + * it's not worth printing anything at all + * + * - if we'd just tried a public key _offer_, + * the message should be "Server refused our + * key" (or no message at all if the key + * came from Pageant) + * + * - if we'd just tried anything else, the + * message really should be "Access denied". + * + * Additionally, if we'd just tried password + * authentication, we should break out of this + * whole loop so as to go back to the username + * prompt. + */ + if (type == AUTH_TYPE_NONE) { + /* do nothing */ + } else if (type == AUTH_TYPE_PUBLICKEY_OFFER_LOUD || + type == AUTH_TYPE_PUBLICKEY_OFFER_QUIET) { + if (type == AUTH_TYPE_PUBLICKEY_OFFER_LOUD) + c_write_str("Server refused our key\r\n"); + logevent("Server refused public key"); + } else { + c_write_str("Access denied\r\n"); + logevent("Access denied"); + if (type == AUTH_TYPE_PASSWORD) { + we_are_in = FALSE; + break; + } + } + } else { + c_write_str("Further authentication required\r\n"); + logevent("Further authentication required"); + } - crWaitUntilV(ispkt); - if (pktin.type != SSH2_MSG_USERAUTH_SUCCESS) { - c_write("Access denied\r\n", 15); - logevent("Authentication refused"); - } else - break; - } + can_pubkey = in_commasep_string("publickey", methods, methlen); + can_passwd = in_commasep_string("password", methods, methlen); + } + + method = 0; + + if (!method && can_pubkey && agent_exists && !tried_agent) { + /* + * Attempt public-key authentication using Pageant. + */ + static unsigned char request[5], *response, *p; + static int responselen; + static int i, nkeys; + static int authed = FALSE; + void *r; + + tried_agent = TRUE; + + logevent("Pageant is running. Requesting keys."); + + /* Request the keys held by the agent. */ + PUT_32BIT(request, 1); + request[4] = SSH2_AGENTC_REQUEST_IDENTITIES; + agent_query(request, 5, &r, &responselen); + response = (unsigned char *)r; + if (response) { + p = response + 5; + nkeys = GET_32BIT(p); p += 4; + { char buf[64]; sprintf(buf, "Pageant has %d SSH2 keys", nkeys); + logevent(buf); } + for (i = 0; i < nkeys; i++) { + static char *pkblob, *alg, *commentp; + static int pklen, alglen, commentlen; + static int siglen, retlen, len; + static char *q, *agentreq, *ret; + + { char buf[64]; sprintf(buf, "Trying Pageant key #%d", i); + logevent(buf); } + pklen = GET_32BIT(p); p += 4; + pkblob = p; p += pklen; + alglen = GET_32BIT(pkblob); + alg = pkblob + 4; + commentlen = GET_32BIT(p); p += 4; + commentp = p; p += commentlen; + ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST); + ssh2_pkt_addstring(username); + ssh2_pkt_addstring("ssh-connection");/* service requested */ + ssh2_pkt_addstring("publickey");/* method */ + ssh2_pkt_addbool(FALSE); /* no signature included */ + ssh2_pkt_addstring_start(); + ssh2_pkt_addstring_data(alg, alglen); + ssh2_pkt_addstring_start(); + ssh2_pkt_addstring_data(pkblob, pklen); + ssh2_pkt_send(); + + crWaitUntilV(ispkt); + if (pktin.type != SSH2_MSG_USERAUTH_PK_OK) { + logevent("Key refused"); + continue; + } + + 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. + * Construct a SIGN_REQUEST. + */ + ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST); + ssh2_pkt_addstring(username); + ssh2_pkt_addstring("ssh-connection"); /* service requested */ + ssh2_pkt_addstring("publickey"); /* method */ + ssh2_pkt_addbool(TRUE); + ssh2_pkt_addstring_start(); + ssh2_pkt_addstring_data(alg, alglen); + ssh2_pkt_addstring_start(); + ssh2_pkt_addstring_data(pkblob, pklen); + + siglen = pktout.length - 5 + 4 + 20; + len = 1; /* message type */ + len += 4 + pklen; /* key blob */ + len += 4 + siglen; /* data to sign */ + len += 4; /* flags */ + agentreq = smalloc(4 + len); + PUT_32BIT(agentreq, len); + q = agentreq + 4; + *q++ = SSH2_AGENTC_SIGN_REQUEST; + PUT_32BIT(q, pklen); q += 4; + memcpy(q, pkblob, pklen); q += pklen; + PUT_32BIT(q, siglen); q += 4; + /* Now the data to be signed... */ + PUT_32BIT(q, 20); q += 4; + memcpy(q, ssh2_session_id, 20); q += 20; + memcpy(q, pktout.data+5, pktout.length-5); + q += pktout.length-5; + /* And finally the (zero) flags word. */ + PUT_32BIT(q, 0); + agent_query(agentreq, len+4, &ret, &retlen); + sfree(agentreq); + 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_pkt_send(); + authed = TRUE; + break; + } else { + logevent("Pageant failed to answer challenge"); + sfree(ret); + } + } + } + if (authed) + continue; + } + } + + if (!method && can_pubkey && *cfg.keyfile && !tried_pubkey_config) { + unsigned char *pub_blob; + char *algorithm, *comment; + int pub_blob_len; + + tried_pubkey_config = TRUE; + + /* + * Try the public key supplied in the configuration. + * + * First, offer the public blob to see if the server is + * willing to accept it. + */ + pub_blob = ssh2_userkey_loadpub(cfg.keyfile, &algorithm, + &pub_blob_len); + if (pub_blob) { + ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST); + ssh2_pkt_addstring(username); + ssh2_pkt_addstring("ssh-connection"); /* service requested */ + ssh2_pkt_addstring("publickey");/* method */ + ssh2_pkt_addbool(FALSE); /* no signature included */ + ssh2_pkt_addstring(algorithm); + ssh2_pkt_addstring_start(); + ssh2_pkt_addstring_data(pub_blob, pub_blob_len); + ssh2_pkt_send(); + logevent("Offered public key"); /* FIXME */ + + crWaitUntilV(ispkt); + if (pktin.type != SSH2_MSG_USERAUTH_PK_OK) { + gotit = TRUE; + type = AUTH_TYPE_PUBLICKEY_OFFER_LOUD; + continue; /* key refused; give up on it */ + } + + logevent("Offer of public key accepted"); + /* + * Actually attempt a serious authentication using + * the key. + */ + if (ssh2_userkey_encrypted(cfg.keyfile, &comment)) { + sprintf(pwprompt, "Passphrase for key \"%.100s\": ", comment); + need_pw = TRUE; + } else { + need_pw = FALSE; + } + c_write_str("Authenticating with public key \""); + c_write_str(comment); + c_write_str("\"\r\n"); + method = AUTH_PUBLICKEY_FILE; + } + } + + if (!method && can_passwd) { + method = AUTH_PASSWORD; + sprintf(pwprompt, "%.90s@%.90s's password: ", username, savedhost); + need_pw = TRUE; + } + + if (need_pw) { + if (ssh_get_line) { + if (!ssh_get_line(pwprompt, password, + sizeof(password), TRUE)) { + /* + * get_line failed to get a password (for + * example because one was supplied on the + * command line which has already failed to + * work). Terminate. + */ + logevent("No more passwords to try"); + ssh_state = SSH_STATE_CLOSED; + crReturnV; + } + } else { + static int pos = 0; + static char c; + + c_write_str(pwprompt); + ssh_send_ok = 1; + + pos = 0; + while (pos >= 0) { + crWaitUntilV(!ispkt); + while (inlen--) switch (c = *in++) { + case 10: case 13: + password[pos] = 0; + pos = -1; + break; + case 8: case 127: + if (pos > 0) + pos--; + break; + case 21: case 27: + pos = 0; + break; + case 3: case 4: + random_save_seed(); + exit(0); + break; + default: + if (((c >= ' ' && c <= '~') || + ((unsigned char)c >= 160)) && pos < 40) + password[pos++] = c; + break; + } + } + c_write_str("\r\n"); + } + } + + if (method == AUTH_PUBLICKEY_FILE) { + /* + * We have our passphrase. Now try the actual authentication. + */ + struct ssh2_userkey *key; + + key = ssh2_load_userkey(cfg.keyfile, password); + if (key == SSH2_WRONG_PASSPHRASE || key == NULL) { + if (key == SSH2_WRONG_PASSPHRASE) { + c_write_str("Wrong passphrase\r\n"); + tried_pubkey_config = FALSE; + } else { + c_write_str("Unable to load private key\r\n"); + tried_pubkey_config = TRUE; + } + /* Send a spurious AUTH_NONE to return to the top. */ + ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST); + ssh2_pkt_addstring(username); + ssh2_pkt_addstring("ssh-connection"); /* service requested */ + ssh2_pkt_addstring("none"); /* method */ + ssh2_pkt_send(); + type = AUTH_TYPE_NONE; + } else { + unsigned char *blob, *sigdata; + int blob_len, sigdata_len; + + /* + * We have loaded the private key and the server + * has announced that it's willing to accept it. + * Hallelujah. Generate a signature and send it. + */ + ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST); + ssh2_pkt_addstring(username); + ssh2_pkt_addstring("ssh-connection"); /* service requested */ + ssh2_pkt_addstring("publickey"); /* method */ + ssh2_pkt_addbool(TRUE); + ssh2_pkt_addstring(key->alg->name); + blob = key->alg->public_blob(key->data, &blob_len); + ssh2_pkt_addstring_start(); + ssh2_pkt_addstring_data(blob, blob_len); + sfree(blob); + + /* + * The data to be signed is: + * + * string session-id + * + * followed by everything so far placed in the + * outgoing packet. + */ + sigdata_len = pktout.length - 5 + 4 + 20; + sigdata = smalloc(sigdata_len); + PUT_32BIT(sigdata, 20); + 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); + sfree(sigdata); + + ssh2_pkt_send(); + type = AUTH_TYPE_PUBLICKEY; + } + } else if (method == AUTH_PASSWORD) { + /* + * We send the password packet lumped tightly together with + * an SSH_MSG_IGNORE packet. The IGNORE packet contains a + * string long enough to make the total length of the two + * packets constant. This should ensure that a passive + * listener doing traffic analyis can't work out the length + * of the password. + * + * For this to work, we need an assumption about the + * maximum length of the password packet. I think 256 is + * pretty conservative. Anyone using a password longer than + * that probably doesn't have much to worry about from + * people who find out how long their password is! + */ + ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST); + ssh2_pkt_addstring(username); + ssh2_pkt_addstring("ssh-connection"); /* service requested */ + ssh2_pkt_addstring("password"); + ssh2_pkt_addbool(FALSE); + ssh2_pkt_addstring(password); + ssh2_pkt_defer(); + /* + * We'll include a string that's an exact multiple of the + * cipher block size. If the cipher is NULL for some + * reason, we don't do this trick at all because we gain + * nothing by it. + */ + if (cscipher) { + int stringlen, i; + + stringlen = (256 - deferred_len); + stringlen += cscipher->blksize - 1; + stringlen -= (stringlen % cscipher->blksize); + if (cscomp) { + /* + * Temporarily disable actual compression, + * so we can guarantee to get this string + * exactly the length we want it. The + * compression-disabling routine should + * return an integer indicating how many + * bytes we should adjust our string length + * by. + */ + stringlen -= cscomp->disable_compression(); + } + ssh2_pkt_init(SSH2_MSG_IGNORE); + ssh2_pkt_addstring_start(); + for (i = 0; i < stringlen; i++) { + char c = (char)random_byte(); + ssh2_pkt_addstring_data(&c, 1); + } + ssh2_pkt_defer(); + } + ssh_pkt_defersend(); + logevent("Sent password"); + type = AUTH_TYPE_PASSWORD; + } else { + c_write_str("No supported authentication methods left to try!\r\n"); + logevent("No supported authentications offered. Disconnecting"); + ssh2_pkt_init(SSH2_MSG_DISCONNECT); + ssh2_pkt_adduint32(SSH2_DISCONNECT_BY_APPLICATION); + ssh2_pkt_addstring("No supported authentication methods available"); + ssh2_pkt_addstring("en"); /* language tag */ + ssh2_pkt_send(); + ssh_state = SSH_STATE_CLOSED; + crReturnV; + } + } + } while (!we_are_in); /* * Now we're authenticated for the connection protocol. The @@ -2272,7 +3382,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) /* * So now create a channel with a session in it. */ - mainchan = malloc(sizeof(struct ssh_channel)); + mainchan = smalloc(sizeof(struct ssh_channel)); mainchan->localid = 100; /* as good as any */ ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN); ssh2_pkt_addstring("session"); @@ -2291,13 +3401,95 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) crReturnV; } mainchan->remoteid = ssh2_pkt_getuint32(); - mainchan->u.v2.remwindow = ssh2_pkt_getuint32(); - mainchan->u.v2.remmaxpkt = ssh2_pkt_getuint32(); - mainchan->u.v2.outbuffer = NULL; - mainchan->u.v2.outbuflen = mainchan->u.v2.outbufsize = 0; + 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; + ssh_channels = newtree234(ssh_channelcmp); + add234(ssh_channels, mainchan); logevent("Opened channel for session"); /* + * Potentially enable X11 forwarding. + */ + if (cfg.x11_forward) { + char proto[20], data[64]; + logevent("Requesting X11 forwarding"); + x11_invent_auth(proto, sizeof(proto), data, sizeof(data)); + ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST); + ssh2_pkt_adduint32(mainchan->remoteid); + ssh2_pkt_addstring("x11-req"); + ssh2_pkt_addbool(1); /* want reply */ + ssh2_pkt_addbool(0); /* many connections */ + ssh2_pkt_addstring(proto); + ssh2_pkt_addstring(data); + ssh2_pkt_adduint32(0); /* screen number */ + 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 (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")); + crReturnV; + } + logevent("X11 forwarding refused"); + } else { + logevent("X11 forwarding enabled"); + ssh_X11_fwd_enabled = TRUE; + } + } + + /* + * Potentially enable agent forwarding. + */ + if (cfg.agentfwd && agent_exists()) { + char proto[20], data[64]; + logevent("Requesting OpenSSH-style agent forwarding"); + x11_invent_auth(proto, sizeof(proto), data, sizeof(data)); + ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST); + ssh2_pkt_adduint32(mainchan->remoteid); + ssh2_pkt_addstring("auth-agent-req@openssh.com"); + 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 (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")); + crReturnV; + } + logevent("Agent forwarding refused"); + } else { + logevent("Agent forwarding enabled"); + ssh_agentfwd_enabled = TRUE; + } + } + + /* * Now allocate a pty for the session. */ if (!cfg.nopty) { @@ -2318,10 +3510,12 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) do { crWaitUntilV(ispkt); if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) { - /* FIXME: be able to handle other channels here */ - if (ssh2_pkt_getuint32() != mainchan->localid) - continue; /* wrong channel */ - mainchan->u.v2.remwindow += ssh2_pkt_getuint32(); + 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 (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST); @@ -2330,10 +3524,13 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) bombout(("Server got confused by pty request")); crReturnV; } - c_write("Server refused to allocate pty\r\n", 32); + c_write_str("Server refused to allocate pty\r\n"); + ssh_editing = ssh_echoing = 1; } else { logevent("Allocated pty"); } + } else { + ssh_editing = ssh_echoing = 1; } /* @@ -2341,7 +3538,11 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) */ ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST); ssh2_pkt_adduint32(mainchan->remoteid); /* recipient channel */ - if (*cfg.remote_cmd) { + 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("exec"); ssh2_pkt_addbool(1); /* want reply */ ssh2_pkt_addstring(cfg.remote_cmd); @@ -2353,10 +3554,12 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) do { crWaitUntilV(ispkt); if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) { - /* FIXME: be able to handle other channels here */ - if (ssh2_pkt_getuint32() != mainchan->localid) - continue; /* wrong channel */ - mainchan->u.v2.remwindow += ssh2_pkt_getuint32(); + 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 (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST); if (pktin.type != SSH2_MSG_CHANNEL_SUCCESS) { @@ -2373,12 +3576,14 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) ssh_state = SSH_STATE_SESSION; if (size_needed) ssh_size(); + if (eof_needed) + ssh_special(TS_EOF); /* * Transfer data! */ + ldisc_send(NULL, 0); /* cause ldisc to notice changes */ ssh_send_ok = 1; - begin_session(); while (1) { static int try_send; crReturnV; @@ -2388,23 +3593,71 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) pktin.type == SSH2_MSG_CHANNEL_EXTENDED_DATA) { char *data; int length; - /* FIXME: be able to handle other channels here */ - if (ssh2_pkt_getuint32() != mainchan->localid) - continue; /* wrong channel */ + unsigned i = ssh2_pkt_getuint32(); + struct ssh_channel *c; + c = find234(ssh_channels, &i, ssh_channelfind); + if (!c) + continue; /* nonexistent channel */ if (pktin.type == SSH2_MSG_CHANNEL_EXTENDED_DATA && ssh2_pkt_getuint32() != SSH2_EXTENDED_DATA_STDERR) continue; /* extended but not stderr */ ssh2_pkt_getstring(&data, &length); if (data) { - from_backend(pktin.type == SSH2_MSG_CHANNEL_EXTENDED_DATA, - data, length); + switch (c->type) { + case CHAN_MAINSESSION: + from_backend(pktin.type == SSH2_MSG_CHANNEL_EXTENDED_DATA, + data, length); + break; + case CHAN_X11: + x11_send(c->u.x11.s, data, length); + break; + case CHAN_AGENT: + while (length > 0) { + if (c->u.a.lensofar < 4) { + int l = min(4 - c->u.a.lensofar, length); + memcpy(c->u.a.msglen + c->u.a.lensofar, data, l); + data += l; length -= l; c->u.a.lensofar += l; + } + if (c->u.a.lensofar == 4) { + c->u.a.totallen = 4 + GET_32BIT(c->u.a.msglen); + c->u.a.message = smalloc(c->u.a.totallen); + memcpy(c->u.a.message, c->u.a.msglen, 4); + } + if (c->u.a.lensofar >= 4 && length > 0) { + int l = min(c->u.a.totallen - c->u.a.lensofar, + length); + memcpy(c->u.a.message + c->u.a.lensofar, data, l); + data += l; length -= l; c->u.a.lensofar += l; + } + if (c->u.a.lensofar == c->u.a.totallen) { + void *reply, *sentreply; + int replylen; + agent_query(c->u.a.message, c->u.a.totallen, + &reply, &replylen); + if (reply) + sentreply = reply; + else { + /* Fake SSH_AGENT_FAILURE. */ + sentreply = "\0\0\0\1\5"; + replylen = 5; + } + ssh2_add_channel_data(c, sentreply, replylen); + try_send = TRUE; + if (reply) + sfree(reply); + sfree(c->u.a.message); + c->u.a.lensofar = 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. + * Enlarge the window again at the remote + * side, just in case it ever runs down and + * they fail to send us any more data. */ ssh2_pkt_init(SSH2_MSG_CHANNEL_WINDOW_ADJUST); - ssh2_pkt_adduint32(mainchan->remoteid); + ssh2_pkt_adduint32(c->remoteid); ssh2_pkt_adduint32(length); ssh2_pkt_send(); } @@ -2415,29 +3668,134 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) } else if (pktin.type == SSH2_MSG_CHANNEL_REQUEST) { continue; /* exit status et al; ignore (FIXME?) */ } else if (pktin.type == SSH2_MSG_CHANNEL_EOF) { - continue; /* remote sends EOF; ignore */ + 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_X11) { + /* + * Remote EOF on an X11 channel means we should + * wrap up and close the channel ourselves. + */ + x11_close(c->u.x11.s); + sshfwd_close(c); + } else if (c->type == CHAN_AGENT) { + sshfwd_close(c); + } } else if (pktin.type == SSH2_MSG_CHANNEL_CLOSE) { - /* FIXME: be able to handle other channels here */ - if (ssh2_pkt_getuint32() != mainchan->localid) - continue; /* wrong channel */ - ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE); - ssh2_pkt_adduint32(mainchan->remoteid); - ssh2_pkt_send(); - /* FIXME: mark the channel as closed */ - if (1 /* FIXME: "all channels are closed" */) { + unsigned i = ssh2_pkt_getuint32(); + struct ssh_channel *c; + enum234 e; + + 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: + break; + case CHAN_AGENT: + break; + } + del234(ssh_channels, c); + sfree(c->v2.outbuffer); + sfree(c); + + /* + * See if that was the last channel left open. + */ + c = first234(ssh_channels, &e); + if (!c) { logevent("All channels closed. Disconnecting"); ssh2_pkt_init(SSH2_MSG_DISCONNECT); + ssh2_pkt_adduint32(SSH2_DISCONNECT_BY_APPLICATION); + ssh2_pkt_addstring("All open channels closed"); + ssh2_pkt_addstring("en"); /* language tag */ ssh2_pkt_send(); ssh_state = SSH_STATE_CLOSED; crReturnV; } continue; /* remote sends close; ignore (FIXME) */ } else if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) { - /* FIXME: be able to handle other channels here */ - if (ssh2_pkt_getuint32() != mainchan->localid) - continue; /* wrong channel */ - mainchan->u.v2.remwindow += ssh2_pkt_getuint32(); + unsigned i = ssh2_pkt_getuint32(); + struct ssh_channel *c; + c = find234(ssh_channels, &i, ssh_channelfind); + if (!c) + continue; /* nonexistent channel */ + mainchan->v2.remwindow += ssh2_pkt_getuint32(); try_send = TRUE; + } else if (pktin.type == SSH2_MSG_CHANNEL_OPEN) { + char *type; + int typelen; + char *error = NULL; + struct ssh_channel *c; + ssh2_pkt_getstring(&type, &typelen); + c = smalloc(sizeof(struct ssh_channel)); + + if (typelen == 3 && !memcmp(type, "x11", 3)) { + if (!ssh_X11_fwd_enabled) + error = "X11 forwarding is not enabled"; + else if ( x11_init(&c->u.x11.s, cfg.x11_display, c) != NULL ) { + error = "Unable to open an X11 connection"; + } else { + c->type = CHAN_X11; + } + } else if (typelen == 22 && + !memcmp(type, "auth-agent@openssh.com", 3)) { + if (!ssh_agentfwd_enabled) + error = "Agent forwarding is not enabled"; + else { + c->type = CHAN_AGENT; /* identify channel type */ + c->u.a.lensofar = 0; + } + } else { + error = "Unsupported channel type requested"; + } + + c->remoteid = ssh2_pkt_getuint32(); + if (error) { + ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN_FAILURE); + ssh2_pkt_adduint32(c->remoteid); + ssh2_pkt_adduint32(SSH2_OPEN_CONNECT_FAILED); + ssh2_pkt_addstring(error); + ssh2_pkt_addstring("en"); /* language tag */ + ssh2_pkt_send(); + sfree(c); + } else { + struct ssh_channel *d; + unsigned i; + enum234 e; + + for (i=1, d = first234(ssh_channels, &e); d; + d = next234(&e)) { + if (d->localid > i) + break; /* found a free number */ + i = d->localid + 1; + } + c->localid = i; + 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; + 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(0x4000UL); /* our max pkt size */ + ssh2_pkt_send(); + } } else { bombout(("Strange packet received: type %d", pktin.type)); crReturnV; @@ -2446,40 +3804,17 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) /* * We have spare data. Add it to the channel buffer. */ - if (mainchan->u.v2.outbufsize < - mainchan->u.v2.outbuflen + inlen) { - mainchan->u.v2.outbufsize = - mainchan->u.v2.outbuflen + inlen + 1024; - mainchan->u.v2.outbuffer = srealloc(mainchan->u.v2.outbuffer, - mainchan->u.v2.outbufsize); - } - memcpy(mainchan->u.v2.outbuffer + mainchan->u.v2.outbuflen, - in, inlen); - mainchan->u.v2.outbuflen += inlen; + ssh2_add_channel_data(mainchan, in, inlen); try_send = TRUE; } if (try_send) { + enum234 e; + struct ssh_channel *c; /* - * Try to send data on the channel if we can. (FIXME: - * on _all_ channels.) + * Try to send data on all channels if we can. */ - while (mainchan->u.v2.remwindow > 0 && - mainchan->u.v2.outbuflen > 0) { - unsigned len = mainchan->u.v2.remwindow; - if (len > mainchan->u.v2.outbuflen) - len = mainchan->u.v2.outbuflen; - if (len > mainchan->u.v2.remmaxpkt) - len = mainchan->u.v2.remmaxpkt; - ssh2_pkt_init(SSH2_MSG_CHANNEL_DATA); - ssh2_pkt_adduint32(mainchan->remoteid); - ssh2_pkt_addstring_start(); - ssh2_pkt_addstring_data(mainchan->u.v2.outbuffer, len); - ssh2_pkt_send(); - mainchan->u.v2.outbuflen -= len; - memmove(mainchan->u.v2.outbuffer, mainchan->u.v2.outbuffer+len, - mainchan->u.v2.outbuflen); - mainchan->u.v2.remwindow -= len; - } + for (c = first234(ssh_channels, &e); c; c = next234(&e)) + ssh2_try_send(c); } } @@ -2510,6 +3845,8 @@ static char *ssh_init (char *host, int port, char **realhost) { #endif ssh_send_ok = 0; + ssh_editing = 0; + ssh_echoing = 0; p = connect_to_host(host, port, realhost); if (p != NULL) @@ -2522,7 +3859,7 @@ 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) { - if (s == NULL) + if (s == NULL || ssh_protocol == NULL) return; ssh_protocol(buf, len, 0); @@ -2534,6 +3871,7 @@ static void ssh_send (char *buf, int len) { static void ssh_size(void) { switch (ssh_state) { case SSH_STATE_BEFORE_SIZE: + case SSH_STATE_PREPACKET: case SSH_STATE_CLOSED: break; /* do nothing */ case SSH_STATE_INTERMED: @@ -2557,6 +3895,7 @@ static void ssh_size(void) { ssh2_pkt_send(); } } + break; } } @@ -2567,6 +3906,15 @@ static void ssh_size(void) { */ static void ssh_special (Telnet_Special code) { if (code == TS_EOF) { + if (ssh_state != SSH_STATE_SESSION) { + /* + * Buffer the EOF in case we are pre-SESSION, so we can + * send it as soon as we reach SESSION. + */ + if (code == TS_EOF) + eof_needed = TRUE; + return; + } if (ssh_version == 1) { send_packet(SSH1_CMSG_EOF, PKT_END); } else { @@ -2576,6 +3924,8 @@ static void ssh_special (Telnet_Special code) { } logevent("Sent EOF message"); } else if (code == TS_PING) { + if (ssh_state == SSH_STATE_CLOSED || ssh_state == SSH_STATE_PREPACKET) + return; if (ssh_version == 1) { send_packet(SSH1_MSG_IGNORE, PKT_STR, "", PKT_END); } else { @@ -2592,6 +3942,12 @@ static Socket ssh_socket(void) { return s; } static int ssh_sendok(void) { return ssh_send_ok; } +static int ssh_ldisc(int option) { + if (option == LD_ECHO) return ssh_echoing; + if (option == LD_EDIT) return ssh_editing; + return FALSE; +} + Backend ssh_backend = { ssh_init, ssh_send, @@ -2599,5 +3955,6 @@ Backend ssh_backend = { ssh_special, ssh_socket, ssh_sendok, + ssh_ldisc, 22 };