#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <assert.h>
#include <winsock.h>
#include "putty.h"
#include "ssh.h"
#include "scp.h"
#ifndef FALSE
#define FALSE 0
#endif
#ifndef TRUE
#define TRUE 1
#endif
#define logevent(s) { logevent(s); \
if (IS_SCP && (scp_flags & SCP_VERBOSE) != 0) \
fprintf(stderr, "%s\n", s); }
#define SSH1_MSG_DISCONNECT 1
#define SSH1_SMSG_PUBLIC_KEY 2
#define SSH1_CMSG_SESSION_KEY 3
#define SSH1_CMSG_USER 4
#define SSH1_CMSG_AUTH_RSA 6
#define SSH1_SMSG_AUTH_RSA_CHALLENGE 7
#define SSH1_CMSG_AUTH_RSA_RESPONSE 8
#define SSH1_CMSG_AUTH_PASSWORD 9
#define SSH1_CMSG_REQUEST_PTY 10
#define SSH1_CMSG_WINDOW_SIZE 11
#define SSH1_CMSG_EXEC_SHELL 12
#define SSH1_CMSG_EXEC_CMD 13
#define SSH1_SMSG_SUCCESS 14
#define SSH1_SMSG_FAILURE 15
#define SSH1_CMSG_STDIN_DATA 16
#define SSH1_SMSG_STDOUT_DATA 17
#define SSH1_SMSG_STDERR_DATA 18
#define SSH1_CMSG_EOF 19
#define SSH1_SMSG_EXIT_STATUS 20
#define SSH1_CMSG_EXIT_CONFIRMATION 33
#define SSH1_MSG_IGNORE 32
#define SSH1_MSG_DEBUG 36
#define SSH1_CMSG_AUTH_TIS 39
#define SSH1_SMSG_AUTH_TIS_CHALLENGE 40
#define SSH1_CMSG_AUTH_TIS_RESPONSE 41
#define SSH1_AUTH_TIS 5
#define SSH2_MSG_DISCONNECT 1
#define SSH2_MSG_IGNORE 2
#define SSH2_MSG_UNIMPLEMENTED 3
#define SSH2_MSG_DEBUG 4
#define SSH2_MSG_SERVICE_REQUEST 5
#define SSH2_MSG_SERVICE_ACCEPT 6
#define SSH2_MSG_KEXINIT 20
#define SSH2_MSG_NEWKEYS 21
#define SSH2_MSG_KEXDH_INIT 30
#define SSH2_MSG_KEXDH_REPLY 31
#define SSH2_MSG_USERAUTH_REQUEST 50
#define SSH2_MSG_USERAUTH_FAILURE 51
#define SSH2_MSG_USERAUTH_SUCCESS 52
#define SSH2_MSG_USERAUTH_BANNER 53
#define SSH2_MSG_USERAUTH_PK_OK 60
#define SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ 60
#define SSH2_MSG_GLOBAL_REQUEST 80
#define SSH2_MSG_REQUEST_SUCCESS 81
#define SSH2_MSG_REQUEST_FAILURE 82
#define SSH2_MSG_CHANNEL_OPEN 90
#define SSH2_MSG_CHANNEL_OPEN_CONFIRMATION 91
#define SSH2_MSG_CHANNEL_OPEN_FAILURE 92
#define SSH2_MSG_CHANNEL_WINDOW_ADJUST 93
#define SSH2_MSG_CHANNEL_DATA 94
#define SSH2_MSG_CHANNEL_EXTENDED_DATA 95
#define SSH2_MSG_CHANNEL_EOF 96
#define SSH2_MSG_CHANNEL_CLOSE 97
#define SSH2_MSG_CHANNEL_REQUEST 98
#define SSH2_MSG_CHANNEL_SUCCESS 99
#define SSH2_MSG_CHANNEL_FAILURE 100
#define SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED 1
#define SSH2_OPEN_CONNECT_FAILED 2
#define SSH2_OPEN_UNKNOWN_CHANNEL_TYPE 3
#define SSH2_OPEN_RESOURCE_SHORTAGE 4
#define SSH2_EXTENDED_DATA_STDERR 1
#define GET_32BIT(cp) \
(((unsigned long)(unsigned char)(cp)[0] << 24) | \
((unsigned long)(unsigned char)(cp)[1] << 16) | \
((unsigned long)(unsigned char)(cp)[2] << 8) | \
((unsigned long)(unsigned char)(cp)[3]))
#define PUT_32BIT(cp, value) { \
(cp)[0] = (unsigned char)((value) >> 24); \
(cp)[1] = (unsigned char)((value) >> 16); \
(cp)[2] = (unsigned char)((value) >> 8); \
(cp)[3] = (unsigned char)(value); }
enum { PKT_END, PKT_INT, PKT_CHAR, PKT_DATA, PKT_STR, PKT_BIGNUM };
/* Coroutine mechanics for the sillier bits of the code */
#define crBegin1 static int crLine = 0;
#define crBegin2 switch(crLine) { case 0:;
#define crBegin crBegin1; crBegin2;
#define crFinish(z) } crLine = 0; return (z)
#define crFinishV } crLine = 0; return
#define crReturn(z) \
do {\
crLine=__LINE__; return (z); case __LINE__:;\
} while (0)
#define crReturnV \
do {\
crLine=__LINE__; return; case __LINE__:;\
} while (0)
#define crStop(z) do{ crLine = 0; return (z); }while(0)
#define crStopV do{ crLine = 0; return; }while(0)
#define crWaitUntil(c) do { crReturn(0); } while (!(c))
#define crWaitUntilV(c) do { crReturnV; } while (!(c))
extern struct ssh_cipher ssh_3des;
extern struct ssh_cipher ssh_3des_ssh2;
extern struct ssh_cipher ssh_des;
extern struct ssh_cipher ssh_blowfish;
/* for ssh 2; we miss out single-DES because it isn't supported */
struct ssh_cipher *ciphers[] = { &ssh_3des_ssh2, &ssh_blowfish };
extern struct ssh_kex ssh_diffiehellman;
struct ssh_kex *kex_algs[] = { &ssh_diffiehellman };
extern struct ssh_hostkey ssh_dss;
struct ssh_hostkey *hostkey_algs[] = { &ssh_dss };
extern struct ssh_mac ssh_sha1;
SHA_State exhash;
static void nullmac_key(unsigned char *key) { }
static void nullmac_generate(unsigned char *blk, int len, unsigned long seq) { }
static int nullmac_verify(unsigned char *blk, int len, unsigned long seq) { return 1; }
struct ssh_mac ssh_mac_none = {
nullmac_key, nullmac_key, nullmac_generate, nullmac_verify, "none", 0
};
struct ssh_mac *macs[] = { &ssh_sha1, &ssh_mac_none };
struct ssh_compress ssh_comp_none = {
"none"
};
struct ssh_compress *compressions[] = { &ssh_comp_none };
static SOCKET s = INVALID_SOCKET;
static unsigned char session_key[32];
static struct ssh_cipher *cipher = NULL;
static struct ssh_cipher *cscipher = NULL;
static struct ssh_cipher *sccipher = NULL;
static struct ssh_mac *csmac = NULL;
static struct ssh_mac *scmac = NULL;
static struct ssh_compress *cscomp = NULL;
static struct ssh_compress *sccomp = NULL;
static struct ssh_kex *kex = NULL;
static struct ssh_hostkey *hostkey = NULL;
int scp_flags = 0;
int (*ssh_get_password)(const char *prompt, char *str, int maxlen) = NULL;
static char *savedhost;
static enum {
SSH_STATE_BEFORE_SIZE,
SSH_STATE_INTERMED,
SSH_STATE_SESSION,
SSH_STATE_CLOSED
} ssh_state = SSH_STATE_BEFORE_SIZE;
static int size_needed = FALSE;
static void s_write (char *buf, int len) {
while (len > 0) {
int i = send (s, buf, len, 0);
if (IS_SCP) {
noise_ultralight(i);
if (i <= 0)
fatalbox("Lost connection while sending");
}
if (i > 0)
len -= i, buf += i;
}
}
static int s_read (char *buf, int len) {
int ret = 0;
while (len > 0) {
int i = recv (s, buf, len, 0);
if (IS_SCP)
noise_ultralight(i);
if (i > 0)
len -= i, buf += i, ret += i;
else
return i;
}
return ret;
}
static void c_write (char *buf, int len) {
if (IS_SCP) {
if (len > 0 && buf[len-1] == '\n') len--;
if (len > 0 && buf[len-1] == '\r') len--;
if (len > 0) { fwrite(buf, len, 1, stderr); fputc('\n', stderr); }
return;
}
while (len--)
c_write1(*buf++);
}
struct Packet {
long length;
int type;
unsigned char *data;
unsigned char *body;
long savedpos;
long maxlen;
};
static struct Packet pktin = { 0, 0, NULL, NULL, 0 };
static struct Packet pktout = { 0, 0, NULL, NULL, 0 };
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 int (*s_rdpkt)(unsigned char **data, int *datalen);
/*
* Collect incoming data in the incoming packet buffer.
* Decipher and verify the packet when it is completely read.
* Drop SSH1_MSG_DEBUG and SSH1_MSG_IGNORE packets.
* Update the *data and *datalen variables.
* Return the additional nr of bytes needed, or 0 when
* a complete packet is available.
*/
static int ssh1_rdpkt(unsigned char **data, int *datalen)
{
static long len, pad, biglen, to_read;
static unsigned long realcrc, gotcrc;
static unsigned char *p;
static int i;
crBegin;
next_packet:
pktin.type = 0;
pktin.length = 0;
for (i = len = 0; i < 4; i++) {
while ((*datalen) == 0)
crReturn(4-i);
len = (len << 8) + **data;
(*data)++, (*datalen)--;
}
#ifdef FWHACK
if (len == 0x52656d6f) { /* "Remo"te server has closed ... */
len = 0x300; /* big enough to carry to end */
}
#endif
pad = 8 - (len % 8);
biglen = len + pad;
pktin.length = len - 5;
if (pktin.maxlen < biglen) {
pktin.maxlen = biglen;
pktin.data = (pktin.data == NULL ? malloc(biglen+APIEXTRA) :
realloc(pktin.data, biglen+APIEXTRA));
if (!pktin.data)
fatalbox("Out of memory");
}
to_read = biglen;
p = pktin.data;
while (to_read > 0) {
static int chunk;
chunk = to_read;
while ((*datalen) == 0)
crReturn(to_read);
if (chunk > (*datalen))
chunk = (*datalen);
memcpy(p, *data, chunk);
*data += chunk;
*datalen -= chunk;
p += chunk;
to_read -= chunk;
}
if (cipher)
cipher->decrypt(pktin.data, biglen);
pktin.type = pktin.data[pad];
pktin.body = pktin.data + pad + 1;
realcrc = crc32(pktin.data, biglen-4);
gotcrc = GET_32BIT(pktin.data+biglen-4);
if (gotcrc != realcrc) {
fatalbox("Incorrect CRC received on packet");
}
if (pktin.type == SSH1_SMSG_STDOUT_DATA ||
pktin.type == SSH1_SMSG_STDERR_DATA ||
pktin.type == SSH1_MSG_DEBUG ||
pktin.type == SSH1_SMSG_AUTH_TIS_CHALLENGE) {
long strlen = GET_32BIT(pktin.body);
if (strlen + 4 != pktin.length)
fatalbox("Received data packet with bogus string length");
}
if (pktin.type == SSH1_MSG_DEBUG) {
/* log debug message */
char buf[80];
int strlen = GET_32BIT(pktin.body);
strcpy(buf, "Remote: ");
if (strlen > 70) strlen = 70;
memcpy(buf+8, pktin.body+4, strlen);
buf[8+strlen] = '\0';
logevent(buf);
goto next_packet;
} else if (pktin.type == SSH1_MSG_IGNORE) {
/* do nothing */
goto next_packet;
}
crFinish(0);
}
static int ssh2_rdpkt(unsigned char **data, int *datalen)
{
static long len, pad, payload, packetlen, maclen;
static int i;
static int cipherblk;
static unsigned long incoming_sequence = 0;
crBegin;
next_packet:
pktin.type = 0;
pktin.length = 0;
if (cipher)
cipherblk = cipher->blksize;
else
cipherblk = 8;
if (cipherblk < 8)
cipherblk = 8;
if (pktin.maxlen < cipherblk) {
pktin.maxlen = cipherblk;
pktin.data = (pktin.data == NULL ? malloc(cipherblk+APIEXTRA) :
realloc(pktin.data, cipherblk+APIEXTRA));
if (!pktin.data)
fatalbox("Out of memory");
}
/*
* Acquire and decrypt the first block of the packet. This will
* contain the length and padding details.
*/
for (i = len = 0; i < cipherblk; i++) {
while ((*datalen) == 0)
crReturn(cipherblk-i);
pktin.data[i] = *(*data)++;
(*datalen)--;
}
#ifdef FWHACK
if (!memcmp(pktin.data, "Remo", 4)) {/* "Remo"te server has closed ... */
/* FIXME */
}
#endif
if (sccipher)
sccipher->decrypt(pktin.data, cipherblk);
/*
* Now get the length and padding figures.
*/
len = GET_32BIT(pktin.data);
pad = pktin.data[4];
/*
* This enables us to deduce the payload length.
*/
payload = len - pad - 1;
pktin.length = payload + 5;
/*
* So now we can work out the total packet length.
*/
packetlen = len + 4;
maclen = scmac ? scmac->len : 0;
/*
* Adjust memory allocation if packet is too big.
*/
if (pktin.maxlen < packetlen) {
pktin.maxlen = packetlen;
pktin.data = (pktin.data == NULL ? malloc(packetlen+APIEXTRA) :
realloc(pktin.data, packetlen+APIEXTRA));
if (!pktin.data)
fatalbox("Out of memory");
}
/*
* Read and decrypt the remainder of the packet.
*/
for (i = cipherblk; i < packetlen + maclen; i++) {
while ((*datalen) == 0)
crReturn(packetlen + maclen - i);
pktin.data[i] = *(*data)++;
(*datalen)--;
}
/* Decrypt everything _except_ the MAC. */
if (sccipher)
sccipher->decrypt(pktin.data + cipherblk, packetlen - cipherblk);
#if 0
debug(("Got packet len=%d pad=%d\r\n", len, pad));
for (i = 0; i < packetlen; i++)
debug((" %02x", (unsigned char)pktin.data[i]));
debug(("\r\n"));
#endif
/*
* Check the MAC.
*/
if (scmac && !scmac->verify(pktin.data, len+4, incoming_sequence))
fatalbox("Incorrect MAC received on packet");
incoming_sequence++; /* whether or not we MACed */
pktin.savedpos = 6;
pktin.type = pktin.data[5];
if (pktin.type == SSH2_MSG_IGNORE || pktin.type == SSH2_MSG_DEBUG)
goto next_packet; /* FIXME: print DEBUG message */
crFinish(0);
}
static void ssh_gotdata(unsigned char *data, int datalen)
{
while (datalen > 0) {
if ( s_rdpkt(&data, &datalen) == 0 ) {
ssh_protocol(NULL, 0, 1);
if (ssh_state == SSH_STATE_CLOSED) {
return;
}
}
}
}
static void s_wrpkt_start(int type, int len) {
int pad, biglen;
len += 5; /* type and CRC */
pad = 8 - (len%8);
biglen = len + pad;
pktout.length = len-5;
if (pktout.maxlen < biglen) {
pktout.maxlen = biglen;
#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));
#else
pktout.data = (pktout.data == NULL ? malloc(biglen+4) :
realloc(pktout.data, biglen+4));
#endif
if (!pktout.data)
fatalbox("Out of memory");
}
pktout.type = type;
pktout.body = pktout.data+4+pad+1;
}
static void s_wrpkt(void) {
int pad, len, biglen, i;
unsigned long crc;
len = pktout.length + 5; /* type and CRC */
pad = 8 - (len%8);
biglen = len + pad;
pktout.body[-1] = pktout.type;
for (i=0; i<pad; i++)
pktout.data[i+4] = random_byte();
crc = crc32(pktout.data+4, biglen-4);
PUT_32BIT(pktout.data+biglen, crc);
PUT_32BIT(pktout.data, len);
if (cipher)
cipher->encrypt(pktout.data+4, biglen);
s_write(pktout.data, biglen+4);
}
/*
* Construct a packet with the specified contents and
* send it to the server.
*/
static void send_packet(int pkttype, ...)
{
va_list args;
unsigned char *p, *argp, argchar;
unsigned long argint;
int pktlen, argtype, arglen;
Bignum bn;
int i;
pktlen = 0;
va_start(args, pkttype);
while ((argtype = va_arg(args, int)) != PKT_END) {
switch (argtype) {
case PKT_INT:
(void) va_arg(args, int);
pktlen += 4;
break;
case PKT_CHAR:
(void) va_arg(args, char);
pktlen++;
break;
case PKT_DATA:
(void) va_arg(args, unsigned char *);
arglen = va_arg(args, int);
pktlen += arglen;
break;
case PKT_STR:
argp = va_arg(args, unsigned char *);
arglen = strlen(argp);
pktlen += 4 + arglen;
break;
case PKT_BIGNUM:
bn = va_arg(args, Bignum);
i = 16 * bn[0] - 1;
while ( i > 0 && (bn[i/16+1] >> (i%16)) == 0 )
i--;
pktlen += 2 + (i+7)/8;
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) {
switch (argtype) {
case PKT_INT:
argint = va_arg(args, int);
PUT_32BIT(p, argint);
p += 4;
break;
case PKT_CHAR:
argchar = va_arg(args, unsigned char);
*p = argchar;
p++;
break;
case PKT_DATA:
argp = va_arg(args, unsigned char *);
arglen = va_arg(args, int);
memcpy(p, argp, arglen);
p += arglen;
break;
case PKT_STR:
argp = va_arg(args, 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);
i = 16 * bn[0] - 1;
while ( i > 0 && (bn[i/16+1] >> (i%16)) == 0 )
i--;
*p++ = (i >> 8) & 0xFF;
*p++ = i & 0xFF;
i = (i + 7) / 8;
while (i-- > 0) {
if (i % 2)
*p++ = bn[i/2+1] >> 8;
else
*p++ = bn[i/2+1] & 0xFF;
}
break;
}
}
va_end(args);
s_wrpkt();
}
/*
* Connect to specified host and port.
* Returns an error message, or NULL on success.
* Also places the canonical host name into `realhost'.
*/
static char *connect_to_host(char *host, int port, char **realhost)
{
SOCKADDR_IN addr;
struct hostent *h;
unsigned long a;
#ifdef FWHACK
char *FWhost;
int FWport;
#endif
savedhost = malloc(1+strlen(host));
if (!savedhost)
fatalbox("Out of memory");
strcpy(savedhost, host);
if (port < 0)
port = 22; /* default ssh port */
#ifdef FWHACK
FWhost = host;
FWport = port;
host = FWSTR;
port = 23;
#endif
/*
* Try to find host.
*/
if ( (a = inet_addr(host)) == (unsigned long) INADDR_NONE) {
if ( (h = gethostbyname(host)) == NULL)
switch (WSAGetLastError()) {
case WSAENETDOWN: return "Network is down";
case WSAHOST_NOT_FOUND: case WSANO_DATA:
return "Host does not exist";
case WSATRY_AGAIN: return "Host not found";
default: return "gethostbyname: unknown error";
}
memcpy (&a, h->h_addr, sizeof(a));
*realhost = h->h_name;
} else
*realhost = host;
#ifdef FWHACK
*realhost = FWhost;
#endif
a = ntohl(a);
/*
* Open socket.
*/
s = socket(AF_INET, SOCK_STREAM, 0);
if (s == INVALID_SOCKET)
switch (WSAGetLastError()) {
case WSAENETDOWN: return "Network is down";
case WSAEAFNOSUPPORT: return "TCP/IP support not present";
default: return "socket(): unknown error";
}
/*
* Bind to local address.
*/
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = htonl(INADDR_ANY);
addr.sin_port = htons(0);
if (bind (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
switch (WSAGetLastError()) {
case WSAENETDOWN: return "Network is down";
default: return "bind(): unknown error";
}
/*
* Connect to remote address.
*/
addr.sin_addr.s_addr = htonl(a);
addr.sin_port = htons((short)port);
if (connect (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
switch (WSAGetLastError()) {
case WSAENETDOWN: return "Network is down";
case WSAECONNREFUSED: return "Connection refused";
case WSAENETUNREACH: return "Network is unreachable";
case WSAEHOSTUNREACH: return "No route to host";
default: return "connect(): unknown error";
}
#ifdef FWHACK
send(s, "connect ", 8, 0);
send(s, FWhost, strlen(FWhost), 0);
{
char buf[20];
sprintf(buf, " %d\n", FWport);
send (s, buf, strlen(buf), 0);
}
#endif
return NULL;
}
static int ssh_versioncmp(char *a, char *b) {
char *ae, *be;
unsigned long av, bv;
av = strtoul(a, &ae, 10);
bv = strtoul(b, &be, 10);
if (av != bv) return (av < bv ? -1 : +1);
if (*ae == '.') ae++;
if (*be == '.') be++;
av = strtoul(ae, &ae, 10);
bv = strtoul(be, &be, 10);
if (av != bv) return (av < bv ? -1 : +1);
return 0;
}
/*
* Utility routine for putting an SSH-protocol `string' into a SHA
* state.
*/
#include <stdio.h>
void sha_string(SHA_State *s, void *str, int len) {
unsigned char lenblk[4];
static FILE *fp;
PUT_32BIT(lenblk, len);
if (!fp) fp = fopen("h:\\statham\\windows\\putty\\data","wb");
fwrite(lenblk, 4, 1, fp);
SHA_Bytes(s, lenblk, 4);
fwrite(str, len, 1, fp);
fflush(fp);
SHA_Bytes(s, str, len);
}
/*
* SSH2 packet construction functions.
*/
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));
if (!pktout.data)
fatalbox("Out of memory");
}
memcpy(pktout.data+pktout.length-len, data, len);
}
void ssh2_pkt_addbyte(unsigned char byte) {
ssh2_pkt_adddata(&byte, 1);
}
void ssh2_pkt_init(int pkt_type) {
pktout.length = 5;
ssh2_pkt_addbyte((unsigned char)pkt_type);
}
void ssh2_pkt_addbool(unsigned char value) {
ssh2_pkt_adddata(&value, 1);
}
void ssh2_pkt_adduint32(unsigned long value) {
unsigned char x[4];
PUT_32BIT(x, value);
ssh2_pkt_adddata(x, 4);
}
void ssh2_pkt_addstring_start(void) {
ssh2_pkt_adduint32(0);
pktout.savedpos = pktout.length;
}
void ssh2_pkt_addstring_str(char *data) {
ssh2_pkt_adddata(data, strlen(data));
PUT_32BIT(pktout.data + pktout.savedpos - 4,
pktout.length - pktout.savedpos);
}
void ssh2_pkt_addstring_data(char *data, int len) {
ssh2_pkt_adddata(data, len);
PUT_32BIT(pktout.data + pktout.savedpos - 4,
pktout.length - pktout.savedpos);
}
void ssh2_pkt_addstring(char *data) {
ssh2_pkt_addstring_start();
ssh2_pkt_addstring_str(data);
}
char *ssh2_mpint_fmt(Bignum b, int *len) {
unsigned char *p;
int i, n = b[0];
p = malloc(n * 2 + 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;
}
i = 0;
while (p[i] == 0 && (p[i+1] & 0x80) == 0)
i++;
memmove(p, p+i, n*2+1-i);
*len = n*2+1-i;
return p;
}
void ssh2_pkt_addmp(Bignum b) {
unsigned char *p;
int len;
p = ssh2_mpint_fmt(b, &len);
ssh2_pkt_addstring_start();
ssh2_pkt_addstring_data(p, len);
free(p);
}
void ssh2_pkt_send(void) {
int cipherblk, maclen, padding, i;
static unsigned long outgoing_sequence = 0;
/*
* 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 = cipherblk < 8 ? 8 : cipherblk; /* or 8 if blksize < 8 */
padding = 4;
padding += (cipherblk - (pktout.length + padding) % cipherblk) % cipherblk;
pktout.data[4] = padding;
for (i = 0; i < padding; i++)
pktout.data[pktout.length + i] = random_byte();
PUT_32BIT(pktout.data, pktout.length + padding - 4);
if (csmac)
csmac->generate(pktout.data, pktout.length + padding,
outgoing_sequence);
outgoing_sequence++; /* whether or not we MACed */
#if 0
debug(("Sending packet len=%d\r\n", pktout.length+padding));
for (i = 0; i < pktout.length+padding; i++)
debug((" %02x", (unsigned char)pktout.data[i]));
debug(("\r\n"));
#endif
if (cscipher)
cscipher->encrypt(pktout.data, pktout.length + padding);
maclen = csmac ? csmac->len : 0;
s_write(pktout.data, pktout.length + padding + maclen);
}
#if 0
void bndebug(char *string, Bignum b) {
unsigned char *p;
int i, len;
p = ssh2_mpint_fmt(b, &len);
debug(("%s", string));
for (i = 0; i < len; i++)
debug((" %02x", p[i]));
debug(("\r\n"));
free(p);
}
#endif
void sha_mpint(SHA_State *s, Bignum b) {
unsigned char *p;
int len;
p = ssh2_mpint_fmt(b, &len);
sha_string(s, p, len);
free(p);
}
/*
* SSH2 packet decode functions.
*/
unsigned long ssh2_pkt_getuint32(void) {
unsigned long value;
if (pktin.length - pktin.savedpos < 4)
return 0; /* arrgh, no way to decline (FIXME?) */
value = GET_32BIT(pktin.data+pktin.savedpos);
pktin.savedpos += 4;
return value;
}
void ssh2_pkt_getstring(char **p, int *length) {
*p = NULL;
if (pktin.length - pktin.savedpos < 4)
return;
*length = GET_32BIT(pktin.data+pktin.savedpos);
pktin.savedpos += 4;
if (pktin.length - pktin.savedpos < *length)
return;
*p = pktin.data+pktin.savedpos;
pktin.savedpos += *length;
}
Bignum ssh2_pkt_getmp(void) {
char *p;
int i, j, length;
Bignum b;
ssh2_pkt_getstring(&p, &length);
if (!p)
return NULL;
if (p[0] & 0x80)
fatalbox("internal error: Can't handle negative mpints");
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]);
}
return b;
}
static int do_ssh_init(void) {
char c, *vsp;
char version[10];
char vstring[80];
char vlog[sizeof(vstring)+20];
int i;
#ifdef FWHACK
i = 0;
while (s_read(&c, 1) == 1) {
if (c == 'S' && i < 2) i++;
else if (c == 'S' && i == 2) i = 2;
else if (c == 'H' && i == 2) break;
else i = 0;
}
#else
if (s_read(&c,1) != 1 || c != 'S') return 0;
if (s_read(&c,1) != 1 || c != 'S') return 0;
if (s_read(&c,1) != 1 || c != 'H') return 0;
#endif
strcpy(vstring, "SSH-");
vsp = vstring+4;
if (s_read(&c,1) != 1 || c != '-') return 0;
i = 0;
while (1) {
if (s_read(&c,1) != 1)
return 0;
if (vsp < vstring+sizeof(vstring)-1)
*vsp++ = c;
if (i >= 0) {
if (c == '-') {
version[i] = '\0';
i = -1;
} else if (i < sizeof(version)-1)
version[i++] = c;
}
else if (c == '\n')
break;
}
*vsp = 0;
sprintf(vlog, "Server version: %s", vstring);
vlog[strcspn(vlog, "\r\n")] = '\0';
logevent(vlog);
if (ssh_versioncmp(version, "2.0" /* FIXME: "1.99" */ ) >= 0) {
/*
* This is a v2 server. Begin v2 protocol.
*/
char *verstring = "SSH-2.0-PuTTY";
SHA_Init(&exhash);
/*
* Hash our version string and their version string.
*/
sha_string(&exhash, verstring, strlen(verstring));
sha_string(&exhash, vstring, strcspn(vstring, "\r\n"));
sprintf(vstring, "%s\n", verstring);
sprintf(vlog, "We claim version: %s", verstring);
logevent(vlog);
logevent("Using SSH protocol version 2");
s_write(vstring, strlen(vstring));
ssh_protocol = ssh2_protocol;
s_rdpkt = ssh2_rdpkt;
} else {
/*
* This is a v1 server. Begin v1 protocol.
*/
sprintf(vstring, "SSH-%s-PuTTY\n",
(ssh_versioncmp(version, "1.5") <= 0 ? version : "1.5"));
sprintf(vlog, "We claim version: %s", vstring);
vlog[strcspn(vlog, "\r\n")] = '\0';
logevent(vlog);
logevent("Using SSH protocol version 1");
s_write(vstring, strlen(vstring));
ssh_protocol = ssh1_protocol;
s_rdpkt = ssh1_rdpkt;
}
return 1;
}
/*
* Handle the key exchange and user authentication phases.
*/
static int do_ssh1_login(unsigned char *in, int inlen, int ispkt)
{
int i, j, len;
unsigned char *rsabuf, *keystr1, *keystr2;
unsigned char cookie[8];
struct RSAKey servkey, hostkey;
struct MD5Context md5c;
static unsigned long supported_ciphers_mask, supported_auths_mask;
static int tried_publickey;
static unsigned char session_id[16];
int cipher_type;
crBegin;
if (!ispkt) crWaitUntil(ispkt);
if (pktin.type != SSH1_SMSG_PUBLIC_KEY)
fatalbox("Public key packet not received");
logevent("Received public keys");
memcpy(cookie, pktin.body, 8);
i = makekey(pktin.body+8, &servkey, &keystr1, 0);
j = makekey(pktin.body+8+i, &hostkey, &keystr2, 0);
/*
* Hash the host key and print the hash in the log box. Just as
* a last resort in case the registry's host key checking is
* compromised, we'll allow the user some ability to verify
* host keys by eye.
*/
MD5Init(&md5c);
MD5Update(&md5c, keystr2, hostkey.bytes);
MD5Final(session_id, &md5c);
{
char logmsg[80];
int i;
logevent("Host key MD5 is:");
strcpy(logmsg, " ");
for (i = 0; i < 16; i++)
sprintf(logmsg+strlen(logmsg), "%02x", session_id[i]);
logevent(logmsg);
}
supported_ciphers_mask = GET_32BIT(pktin.body+12+i+j);
supported_auths_mask = GET_32BIT(pktin.body+16+i+j);
MD5Init(&md5c);
MD5Update(&md5c, keystr2, hostkey.bytes);
MD5Update(&md5c, keystr1, servkey.bytes);
MD5Update(&md5c, pktin.body, 8);
MD5Final(session_id, &md5c);
for (i=0; i<32; i++)
session_key[i] = random_byte();
len = (hostkey.bytes > servkey.bytes ? hostkey.bytes : servkey.bytes);
rsabuf = malloc(len);
if (!rsabuf)
fatalbox("Out of memory");
/*
* Verify the host key.
*/
{
/*
* First format the key into a string.
*/
int len = rsastr_len(&hostkey);
char *keystr = malloc(len);
if (!keystr)
fatalbox("Out of memory");
rsastr_fmt(keystr, &hostkey);
verify_ssh_host_key(savedhost, keystr);
free(keystr);
}
for (i=0; i<32; i++) {
rsabuf[i] = session_key[i];
if (i < 16)
rsabuf[i] ^= session_id[i];
}
if (hostkey.bytes > servkey.bytes) {
rsaencrypt(rsabuf, 32, &servkey);
rsaencrypt(rsabuf, servkey.bytes, &hostkey);
} else {
rsaencrypt(rsabuf, 32, &hostkey);
rsaencrypt(rsabuf, hostkey.bytes, &servkey);
}
logevent("Encrypted session key");
cipher_type = cfg.cipher == CIPHER_BLOWFISH ? SSH_CIPHER_BLOWFISH :
cfg.cipher == CIPHER_DES ? SSH_CIPHER_DES :
SSH_CIPHER_3DES;
if ((supported_ciphers_mask & (1 << cipher_type)) == 0) {
c_write("Selected cipher not supported, falling back to 3DES\r\n", 53);
cipher_type = SSH_CIPHER_3DES;
}
switch (cipher_type) {
case SSH_CIPHER_3DES: logevent("Using 3DES encryption"); break;
case SSH_CIPHER_DES: logevent("Using single-DES encryption"); break;
case SSH_CIPHER_BLOWFISH: logevent("Using Blowfish encryption"); break;
}
send_packet(SSH1_CMSG_SESSION_KEY,
PKT_CHAR, cipher_type,
PKT_DATA, cookie, 8,
PKT_CHAR, (len*8) >> 8, PKT_CHAR, (len*8) & 0xFF,
PKT_DATA, rsabuf, len,
PKT_INT, 0,
PKT_END);
logevent("Trying to enable encryption...");
free(rsabuf);
cipher = cipher_type == SSH_CIPHER_BLOWFISH ? &ssh_blowfish :
cipher_type == SSH_CIPHER_DES ? &ssh_des :
&ssh_3des;
cipher->sesskey(session_key);
crWaitUntil(ispkt);
if (pktin.type != SSH1_SMSG_SUCCESS)
fatalbox("Encryption not successfully enabled");
logevent("Successfully started encryption");
fflush(stdout);
{
static char username[100];
static int pos = 0;
static char c;
if (!IS_SCP && !*cfg.username) {
c_write("login as: ", 10);
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];
strncpy(username, cfg.username, 99);
username[99] = '\0';
if (!IS_SCP) {
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)];
sprintf(userlog, "Sent username \"%s\"", username);
logevent(userlog);
}
}
crWaitUntil(ispkt);
tried_publickey = 0;
while (pktin.type == SSH1_SMSG_FAILURE) {
static char password[100];
static int pos;
static char c;
static int pwpkt_type;
/*
* Show password prompt, having first obtained it via a TIS
* exchange if we're doing TIS authentication.
*/
pwpkt_type = SSH1_CMSG_AUTH_PASSWORD;
if (*cfg.keyfile && !tried_publickey)
pwpkt_type = SSH1_CMSG_AUTH_RSA;
if (pwpkt_type == SSH1_CMSG_AUTH_PASSWORD && IS_SCP) {
char prompt[200];
sprintf(prompt, "%s@%s's password: ", cfg.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;
crReturn(1);
}
} else {
if (pktin.type == SSH1_SMSG_FAILURE &&
cfg.try_tis_auth &&
(supported_auths_mask & (1<<SSH1_AUTH_TIS))) {
pwpkt_type = SSH1_CMSG_AUTH_TIS_RESPONSE;
logevent("Requested TIS authentication");
send_packet(SSH1_CMSG_AUTH_TIS, PKT_END);
crWaitUntil(ispkt);
if (pktin.type != SSH1_SMSG_AUTH_TIS_CHALLENGE) {
logevent("TIS authentication declined");
c_write("TIS authentication refused.\r\n", 29);
} else {
int challengelen = ((pktin.body[0] << 24) |
(pktin.body[1] << 16) |
(pktin.body[2] << 8) |
(pktin.body[3]));
logevent("Received TIS challenge");
c_write(pktin.body+4, challengelen);
}
}
if (pwpkt_type == SSH1_CMSG_AUTH_PASSWORD)
c_write("password: ", 10);
if (pwpkt_type == SSH1_CMSG_AUTH_RSA) {
c_write("Trying public key authentication.\r\n", 35);
if (!rsakey_encrypted(cfg.keyfile)) {
c_write("No passphrase required.\r\n", 25);
goto tryauth;
}
c_write("passphrase: ", 12);
}
pos = 0;
while (pos >= 0) {
crWaitUntil(!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 < sizeof(password))
password[pos++] = c;
break;
}
}
c_write("\r\n", 2);
}
tryauth:
if (pwpkt_type == SSH1_CMSG_AUTH_RSA) {
/*
* Try public key authentication with the specified
* key file.
*/
static struct RSAKey pubkey;
static Bignum challenge, response;
static int i;
static unsigned char buffer[32];
tried_publickey = 1;
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);
continue; /* go and try password */
}
if (i == -1) {
c_write("Wrong passphrase.\r\n", 19);
tried_publickey = 0;
continue; /* try again */
}
/*
* Send a public key attempt.
*/
send_packet(SSH1_CMSG_AUTH_RSA,
PKT_BIGNUM, pubkey.modulus, PKT_END);
crWaitUntil(ispkt);
if (pktin.type == SSH1_SMSG_FAILURE) {
c_write("Server refused our public key.\r\n", 32);
continue; /* go and try password */
}
if (pktin.type != SSH1_SMSG_AUTH_RSA_CHALLENGE)
fatalbox("Bizarre response to offer of public key");
ssh1_read_bignum(pktin.body, &challenge);
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;
}
MD5Init(&md5c);
MD5Update(&md5c, buffer, 32);
MD5Update(&md5c, session_id, 16);
MD5Final(buffer, &md5c);
send_packet(SSH1_CMSG_AUTH_RSA_RESPONSE,
PKT_DATA, buffer, 16, PKT_END);
crWaitUntil(ispkt);
if (pktin.type == SSH1_SMSG_FAILURE) {
c_write("Failed to authenticate with our public key.\r\n", 45);
continue; /* go and try password */
} else if (pktin.type != SSH1_SMSG_SUCCESS) {
fatalbox("Bizarre response to RSA authentication response");
}
break; /* we're through! */
} 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) {
c_write("Access denied\r\n", 15);
logevent("Authentication refused");
} else if (pktin.type == SSH1_MSG_DISCONNECT) {
logevent("Received disconnect request");
ssh_state = SSH_STATE_CLOSED;
crReturn(1);
} else if (pktin.type != SSH1_SMSG_SUCCESS) {
fatalbox("Strange packet received, type %d", pktin.type);
}
}
logevent("Authentication successful");
crFinish(1);
}
static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) {
crBegin;
random_init();
while (!do_ssh1_login(in, inlen, ispkt)) {
crReturnV;
}
if (ssh_state == SSH_STATE_CLOSED)
crReturnV;
if (!cfg.nopty) {
send_packet(SSH1_CMSG_REQUEST_PTY,
PKT_STR, cfg.termtype,
PKT_INT, rows, PKT_INT, cols,
PKT_INT, 0, PKT_INT, 0,
PKT_CHAR, 0,
PKT_END);
ssh_state = SSH_STATE_INTERMED;
do { crReturnV; } while (!ispkt);
if (pktin.type != SSH1_SMSG_SUCCESS && pktin.type != SSH1_SMSG_FAILURE) {
fatalbox("Protocol confusion");
} else if (pktin.type == SSH1_SMSG_FAILURE) {
c_write("Server refused to allocate pty\r\n", 32);
}
logevent("Allocated pty");
}
send_packet(SSH1_CMSG_EXEC_SHELL, PKT_END);
logevent("Started session");
ssh_state = SSH_STATE_SESSION;
if (size_needed)
ssh_size();
while (1) {
crReturnV;
if (ispkt) {
if (pktin.type == SSH1_SMSG_STDOUT_DATA ||
pktin.type == SSH1_SMSG_STDERR_DATA) {
long len = GET_32BIT(pktin.body);
c_write(pktin.body+4, len);
} else if (pktin.type == SSH1_MSG_DISCONNECT) {
ssh_state = SSH_STATE_CLOSED;
logevent("Received disconnect request");
} else if (pktin.type == SSH1_SMSG_SUCCESS) {
/* may be from EXEC_SHELL on some servers */
} else if (pktin.type == SSH1_SMSG_FAILURE) {
/* may be from EXEC_SHELL on some servers
* if no pty is available or in other odd cases. Ignore */
} else if (pktin.type == SSH1_SMSG_EXIT_STATUS) {
send_packet(SSH1_CMSG_EXIT_CONFIRMATION, PKT_END);
} else {
fatalbox("Strange packet received: type %d", pktin.type);
}
} else {
send_packet(SSH1_CMSG_STDIN_DATA,
PKT_INT, inlen, PKT_DATA, in, inlen, PKT_END);
}
}
crFinishV;
}
/*
* Utility routine for decoding comma-separated strings in KEXINIT.
*/
int in_commasep_string(char *needle, char *haystack, int haylen) {
int needlen = strlen(needle);
while (1) {
/*
* Is it at the start of the string?
*/
if (haylen >= needlen && /* haystack is long enough */
!memcmp(needle, haystack, needlen) && /* initial match */
(haylen == needlen || haystack[needlen] == ',')
/* either , or EOS follows */
)
return 1;
/*
* If not, search for the next comma and resume after that.
* If no comma found, terminate.
*/
while (haylen > 0 && *haystack != ',')
haylen--, haystack++;
if (haylen == 0)
return 0;
haylen--, haystack++; /* skip over comma itself */
}
}
/*
* SSH2 key creation method.
*/
void ssh2_mkkey(Bignum K, char *H, 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_Final(&s, keyspace);
/* Next 20 bytes. */
SHA_Init(&s);
sha_mpint(&s, K);
SHA_Bytes(&s, H, 20);
SHA_Bytes(&s, keyspace, 20);
SHA_Final(&s, keyspace+20);
}
/*
* Handle the SSH2 transport layer.
*/
static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
{
static int i, len;
static char *str;
static Bignum e, f, K;
static struct ssh_cipher *cscipher_tobe = NULL;
static struct ssh_cipher *sccipher_tobe = NULL;
static struct ssh_mac *csmac_tobe = NULL;
static struct ssh_mac *scmac_tobe = NULL;
static struct ssh_compress *cscomp_tobe = NULL;
static struct ssh_compress *sccomp_tobe = NULL;
static char *hostkeydata, *sigdata, *keystr;
static int hostkeylen, siglen;
static unsigned char exchange_hash[20];
static unsigned char keyspace[40];
crBegin;
random_init();
begin_key_exchange:
/*
* Construct and send our key exchange packet.
*/
ssh2_pkt_init(SSH2_MSG_KEXINIT);
for (i = 0; i < 16; i++)
ssh2_pkt_addbyte((unsigned char)random_byte());
/* List key exchange algorithms. */
ssh2_pkt_addstring_start();
for (i = 0; i < lenof(kex_algs); i++) {
ssh2_pkt_addstring_str(kex_algs[i]->name);
if (i < lenof(kex_algs)-1)
ssh2_pkt_addstring_str(",");
}
/* List server host key algorithms. */
ssh2_pkt_addstring_start();
for (i = 0; i < lenof(hostkey_algs); i++) {
ssh2_pkt_addstring_str(hostkey_algs[i]->name);
if (i < lenof(hostkey_algs)-1)
ssh2_pkt_addstring_str(",");
}
/* List client->server encryption algorithms. */
ssh2_pkt_addstring_start();
for (i = 0; i < lenof(ciphers); i++) {
ssh2_pkt_addstring_str(ciphers[i]->name);
if (i < lenof(ciphers)-1)
ssh2_pkt_addstring_str(",");
}
/* List server->client encryption algorithms. */
ssh2_pkt_addstring_start();
for (i = 0; i < lenof(ciphers); i++) {
ssh2_pkt_addstring_str(ciphers[i]->name);
if (i < lenof(ciphers)-1)
ssh2_pkt_addstring_str(",");
}
/* List client->server MAC algorithms. */
ssh2_pkt_addstring_start();
for (i = 0; i < lenof(macs); i++) {
ssh2_pkt_addstring_str(macs[i]->name);
if (i < lenof(macs)-1)
ssh2_pkt_addstring_str(",");
}
/* List server->client MAC algorithms. */
ssh2_pkt_addstring_start();
for (i = 0; i < lenof(macs); i++) {
ssh2_pkt_addstring_str(macs[i]->name);
if (i < lenof(macs)-1)
ssh2_pkt_addstring_str(",");
}
/* 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)
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)
ssh2_pkt_addstring_str(",");
}
/* List client->server languages. Empty list. */
ssh2_pkt_addstring_start();
/* List server->client languages. Empty list. */
ssh2_pkt_addstring_start();
/* First KEX packet does _not_ follow, because we're not that brave. */
ssh2_pkt_addbool(FALSE);
/* Reserved. */
ssh2_pkt_adduint32(0);
sha_string(&exhash, pktout.data+5, pktout.length-5);
ssh2_pkt_send();
if (!ispkt) crWaitUntil(ispkt);
sha_string(&exhash, pktin.data+5, pktin.length-5);
/*
* Now examine the other side's KEXINIT to see what we're up
* to.
*/
if (pktin.type != SSH2_MSG_KEXINIT) {
fatalbox("expected key exchange packet from server");
}
kex = NULL; hostkey = NULL; cscipher_tobe = NULL; sccipher_tobe = NULL;
csmac_tobe = NULL; scmac_tobe = NULL; cscomp_tobe = NULL; sccomp_tobe = NULL;
pktin.savedpos += 16; /* skip garbage cookie */
ssh2_pkt_getstring(&str, &len); /* key exchange algorithms */
for (i = 0; i < lenof(kex_algs); i++) {
if (in_commasep_string(kex_algs[i]->name, str, len)) {
kex = kex_algs[i];
break;
}
}
ssh2_pkt_getstring(&str, &len); /* host key algorithms */
for (i = 0; i < lenof(hostkey_algs); i++) {
if (in_commasep_string(hostkey_algs[i]->name, str, len)) {
hostkey = hostkey_algs[i];
break;
}
}
ssh2_pkt_getstring(&str, &len); /* client->server cipher */
for (i = 0; i < lenof(ciphers); i++) {
if (in_commasep_string(ciphers[i]->name, str, len)) {
cscipher_tobe = ciphers[i];
break;
}
}
ssh2_pkt_getstring(&str, &len); /* server->client cipher */
for (i = 0; i < lenof(ciphers); i++) {
if (in_commasep_string(ciphers[i]->name, str, len)) {
sccipher_tobe = ciphers[i];
break;
}
}
ssh2_pkt_getstring(&str, &len); /* client->server mac */
for (i = 0; i < lenof(macs); i++) {
if (in_commasep_string(macs[i]->name, str, len)) {
csmac_tobe = macs[i];
break;
}
}
ssh2_pkt_getstring(&str, &len); /* server->client mac */
for (i = 0; i < lenof(macs); i++) {
if (in_commasep_string(macs[i]->name, str, len)) {
scmac_tobe = macs[i];
break;
}
}
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];
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];
break;
}
}
/*
* Currently we only support Diffie-Hellman and DSS, so let's
* bomb out if those aren't selected.
*/
if (kex != &ssh_diffiehellman || hostkey != &ssh_dss)
fatalbox("internal fault: chaos in SSH 2 transport layer");
/*
* Now we begin the fun. Generate and send e for Diffie-Hellman.
*/
e = dh_create_e();
ssh2_pkt_init(SSH2_MSG_KEXDH_INIT);
ssh2_pkt_addmp(e);
ssh2_pkt_send();
crWaitUntil(ispkt);
if (pktin.type != SSH2_MSG_KEXDH_REPLY) {
fatalbox("expected key exchange packet from server");
}
ssh2_pkt_getstring(&hostkeydata, &hostkeylen);
f = ssh2_pkt_getmp();
ssh2_pkt_getstring(&sigdata, &siglen);
K = dh_find_K(f);
sha_string(&exhash, hostkeydata, hostkeylen);
sha_mpint(&exhash, e);
sha_mpint(&exhash, f);
sha_mpint(&exhash, K);
SHA_Final(&exhash, exchange_hash);
#if 0
debug(("Exchange hash is:\r\n"));
for (i = 0; i < 20; i++)
debug((" %02x", exchange_hash[i]));
debug(("\r\n"));
#endif
hostkey->setkey(hostkeydata, hostkeylen);
if (!hostkey->verifysig(sigdata, siglen, exchange_hash, 20))
fatalbox("Server failed host key check");
/*
* Expect SSH2_MSG_NEWKEYS from server.
*/
crWaitUntil(ispkt);
if (pktin.type != SSH2_MSG_NEWKEYS)
fatalbox("expected new-keys packet from server");
/*
* Authenticate remote host: verify host key. (We've already
* checked the signature of the exchange hash.)
*/
keystr = hostkey->fmtkey();
verify_ssh_host_key(savedhost, keystr);
free(keystr);
/*
* Send SSH2_MSG_NEWKEYS.
*/
ssh2_pkt_init(SSH2_MSG_NEWKEYS);
ssh2_pkt_send();
/*
* Create and initialise session keys.
*/
cscipher = cscipher_tobe;
sccipher = sccipher_tobe;
csmac = csmac_tobe;
scmac = scmac_tobe;
cscomp = cscomp_tobe;
sccomp = sccomp_tobe;
/*
* Set IVs after keys.
*/
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);
/*
* Now we're encrypting. Begin returning 1 to the protocol main
* function so that other things can run on top of the
* transport. If we ever see a KEXINIT, we must go back to the
* start.
*/
do {
crReturn(1);
} while (!(ispkt && pktin.type == SSH2_MSG_KEXINIT));
goto begin_key_exchange;
crFinish(1);
}
/*
* Handle the SSH2 userauth and connection layers.
*/
static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
{
static unsigned long their_channel;
static unsigned long remote_winsize;
static unsigned long remote_maxpkt;
crBegin;
/*
* Request userauth protocol, and await a response to it.
*/
ssh2_pkt_init(SSH2_MSG_SERVICE_REQUEST);
ssh2_pkt_addstring("ssh-userauth");
ssh2_pkt_send();
crWaitUntilV(ispkt);
if (pktin.type != SSH2_MSG_SERVICE_ACCEPT)
fatalbox("Server refused user authentication protocol");
/*
* FIXME: currently we support only password authentication.
* (This places us technically in violation of the SSH2 spec.
* We must fix this.)
*/
while (1) {
/*
* Get a username and a password.
*/
static char username[100];
static char password[100];
static int pos = 0;
static char c;
if (!IS_SCP && !*cfg.username) {
c_write("login as: ", 10);
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);
username[strcspn(username, "\n\r")] = '\0';
} else {
char stuff[200];
strncpy(username, cfg.username, 99);
username[99] = '\0';
if (!IS_SCP) {
sprintf(stuff, "Using username \"%s\".\r\n", username);
c_write(stuff, strlen(stuff));
}
}
if (IS_SCP) {
char prompt[200];
sprintf(prompt, "%s@%s's password: ", cfg.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);
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);
}
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();
crWaitUntilV(ispkt);
if (pktin.type != SSH2_MSG_USERAUTH_SUCCESS) {
c_write("Access denied\r\n", 15);
logevent("Authentication refused");
} else
break;
}
/*
* Now we're authenticated for the connection protocol. The
* connection protocol will automatically have started at this
* point; there's no need to send SERVICE_REQUEST.
*/
/*
* So now create a channel with a session in it.
*/
ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN);
ssh2_pkt_addstring("session");
ssh2_pkt_adduint32(100); /* as good as any */
ssh2_pkt_adduint32(0xFFFFFFFFUL); /* very big window which we ignore */
ssh2_pkt_adduint32(0xFFFFFFFFUL); /* very big max pkt size */
ssh2_pkt_send();
crWaitUntilV(ispkt);
if (pktin.type != SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) {
fatalbox("Server refused to open a session");
/* FIXME: error data comes back in FAILURE packet */
}
if (ssh2_pkt_getuint32() != 100) {
fatalbox("Server's channel confirmation cited wrong channel");
}
their_channel = ssh2_pkt_getuint32();
remote_winsize = ssh2_pkt_getuint32();
remote_maxpkt = ssh2_pkt_getuint32();
logevent("Opened channel for session");
/*
* Now allocate a pty for the session.
*/
ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
ssh2_pkt_adduint32(their_channel); /* recipient channel */
ssh2_pkt_addstring("pty-req");
ssh2_pkt_addbool(1); /* want reply */
ssh2_pkt_addstring(cfg.termtype);
ssh2_pkt_adduint32(cols);
ssh2_pkt_adduint32(rows);
ssh2_pkt_adduint32(0); /* pixel width */
ssh2_pkt_adduint32(0); /* pixel height */
ssh2_pkt_addstring_start();
ssh2_pkt_addstring_data("\0", 1); /* TTY_OP_END, no special options */
ssh2_pkt_send();
do { /* FIXME: pay attention to these */
crWaitUntilV(ispkt);
} while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
if (pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
if (pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
fatalbox("Server got confused by pty request");
}
c_write("Server refused to allocate pty\r\n", 32);
} else {
logevent("Allocated pty");
}
/*
* Start a shell.
*/
ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
ssh2_pkt_adduint32(their_channel); /* recipient channel */
ssh2_pkt_addstring("shell");
ssh2_pkt_addbool(1); /* want reply */
ssh2_pkt_send();
do { /* FIXME: pay attention to these */
crWaitUntilV(ispkt);
} while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
if (pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
if (pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
fatalbox("Server got confused by shell request");
}
fatalbox("Server refused to start a shell");
} else {
logevent("Started a shell");
}
/*
* Transfer data!
*/
while (1) {
crReturnV;
if (ispkt) {
if (pktin.type == SSH2_MSG_CHANNEL_DATA ||
pktin.type == SSH2_MSG_CHANNEL_EXTENDED_DATA) {
char *data;
int length;
if (ssh2_pkt_getuint32() != 100)
continue; /* wrong 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)
c_write(data, length);
} else if (pktin.type == SSH2_MSG_DISCONNECT) {
ssh_state = SSH_STATE_CLOSED;
logevent("Received disconnect request");
} else if (pktin.type == SSH2_MSG_CHANNEL_REQUEST) {
continue; /* exit status et al; ignore (FIXME?) */
} else if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
continue; /* ignore for now (FIXME!) */
} else {
fatalbox("Strange packet received: type %d", pktin.type);
}
} else {
/* FIXME: for now, ignore window size */
ssh2_pkt_init(SSH2_MSG_CHANNEL_DATA);
ssh2_pkt_adduint32(their_channel);
ssh2_pkt_addstring_start();
ssh2_pkt_addstring_data(in, inlen);
ssh2_pkt_send();
}
}
crFinishV;
}
/*
* Handle the top-level SSH2 protocol.
*/
static void ssh2_protocol(unsigned char *in, int inlen, int ispkt)
{
if (do_ssh2_transport(in, inlen, ispkt) == 0)
return;
do_ssh2_authconn(in, inlen, ispkt);
}
/*
* Called to set up the connection. Will arrange for WM_NETEVENT
* messages to be passed to the specified window, whose window
* procedure should then call telnet_msg().
*
* Returns an error message, or NULL on success.
*/
static char *ssh_init (HWND hwnd, char *host, int port, char **realhost) {
char *p;
#ifdef MSCRYPTOAPI
if(crypto_startup() == 0)
return "Microsoft high encryption pack not installed!";
#endif
p = connect_to_host(host, port, realhost);
if (p != NULL)
return p;
if (!do_ssh_init())
return "Protocol initialisation error";
if (WSAAsyncSelect (s, hwnd, WM_NETEVENT, FD_READ | FD_CLOSE) == SOCKET_ERROR)
switch (WSAGetLastError()) {
case WSAENETDOWN: return "Network is down";
default: return "WSAAsyncSelect(): unknown error";
}
return NULL;
}
/*
* Process a WM_NETEVENT message. Will return 0 if the connection
* has closed, or <0 for a socket error.
*/
static int ssh_msg (WPARAM wParam, LPARAM lParam) {
int ret;
char buf[256];
/*
* Because reading less than the whole of the available pending
* data can generate an FD_READ event, we need to allow for the
* possibility that FD_READ may arrive with FD_CLOSE already in
* the queue; so it's possible that we can get here even with s
* invalid. If so, we return 1 and don't worry about it.
*/
if (s == INVALID_SOCKET)
return 1;
if (WSAGETSELECTERROR(lParam) != 0)
return -WSAGETSELECTERROR(lParam);
switch (WSAGETSELECTEVENT(lParam)) {
case FD_READ:
case FD_CLOSE:
ret = recv(s, buf, sizeof(buf), 0);
if (ret < 0 && WSAGetLastError() == WSAEWOULDBLOCK)
return 1;
if (ret < 0) /* any _other_ error */
return -10000-WSAGetLastError();
if (ret == 0) {
s = INVALID_SOCKET;
return 0;
}
ssh_gotdata (buf, ret);
if (ssh_state == SSH_STATE_CLOSED) {
closesocket(s);
s = INVALID_SOCKET;
return 0;
}
return 1;
}
return 1; /* shouldn't happen, but WTF */
}
/*
* Called to send data down the Telnet connection.
*/
static void ssh_send (char *buf, int len) {
if (s == INVALID_SOCKET)
return;
ssh_protocol(buf, len, 0);
}
/*
* Called to set the size of the window from Telnet's POV.
*/
static void ssh_size(void) {
switch (ssh_state) {
case SSH_STATE_BEFORE_SIZE:
case SSH_STATE_CLOSED:
break; /* do nothing */
case SSH_STATE_INTERMED:
size_needed = TRUE; /* buffer for later */
break;
case SSH_STATE_SESSION:
if (!cfg.nopty) {
send_packet(SSH1_CMSG_WINDOW_SIZE,
PKT_INT, rows, PKT_INT, cols,
PKT_INT, 0, PKT_INT, 0, PKT_END);
}
}
}
/*
* (Send Telnet special codes)
*/
static void ssh_special (Telnet_Special code) {
/* do nothing */
}
/*
* Read and decrypt one incoming SSH packet.
* (only used by pSCP)
*/
static void get_packet(void)
{
unsigned char buf[4096], *p;
long to_read;
int len;
assert(IS_SCP);
p = NULL;
len = 0;
while ((to_read = s_rdpkt(&p, &len)) > 0) {
if (to_read > sizeof(buf)) to_read = sizeof(buf);
len = s_read(buf, to_read);
if (len != to_read) {
closesocket(s);
s = INVALID_SOCKET;
return;
}
p = buf;
}
assert(len == 0);
}
/*
* Receive a block of data over the SSH link. Block until
* all data is available. Return nr of bytes read (0 if lost connection).
* (only used by pSCP)
*/
int ssh_scp_recv(unsigned char *buf, int len)
{
static int pending_input_len = 0;
static unsigned char *pending_input_ptr;
int to_read = len;
assert(IS_SCP);
if (pending_input_len >= to_read) {
memcpy(buf, pending_input_ptr, to_read);
pending_input_ptr += to_read;
pending_input_len -= to_read;
return len;
}
if (pending_input_len > 0) {
memcpy(buf, pending_input_ptr, pending_input_len);
buf += pending_input_len;
to_read -= pending_input_len;
pending_input_len = 0;
}
if (s == INVALID_SOCKET)
return 0;
while (to_read > 0) {
get_packet();
if (s == INVALID_SOCKET)
return 0;
if (pktin.type == SSH1_SMSG_STDOUT_DATA) {
int plen = GET_32BIT(pktin.body);
if (plen <= to_read) {
memcpy(buf, pktin.body + 4, plen);
buf += plen;
to_read -= plen;
} else {
memcpy(buf, pktin.body + 4, to_read);
pending_input_len = plen - to_read;
pending_input_ptr = pktin.body + 4 + to_read;
to_read = 0;
}
} else if (pktin.type == SSH1_SMSG_STDERR_DATA) {
int plen = GET_32BIT(pktin.body);
fwrite(pktin.body + 4, plen, 1, stderr);
} else if (pktin.type == SSH1_MSG_DISCONNECT) {
logevent("Received disconnect request");
} else if (pktin.type == SSH1_SMSG_SUCCESS ||
pktin.type == SSH1_SMSG_FAILURE) {
/* ignore */
} else if (pktin.type == SSH1_SMSG_EXIT_STATUS) {
char logbuf[100];
sprintf(logbuf, "Remote exit status: %d", GET_32BIT(pktin.body));
logevent(logbuf);
send_packet(SSH1_CMSG_EXIT_CONFIRMATION, PKT_END);
logevent("Closing connection");
closesocket(s);
s = INVALID_SOCKET;
} else {
fatalbox("Strange packet received: type %d", pktin.type);
}
}
return len;
}
/*
* Send a block of data over the SSH link.
* Block until all data is sent.
* (only used by pSCP)
*/
void ssh_scp_send(unsigned char *buf, int len)
{
assert(IS_SCP);
if (s == INVALID_SOCKET)
return;
send_packet(SSH1_CMSG_STDIN_DATA,
PKT_INT, len, PKT_DATA, buf, len, PKT_END);
}
/*
* Send an EOF notification to the server.
* (only used by pSCP)
*/
void ssh_scp_send_eof(void)
{
assert(IS_SCP);
if (s == INVALID_SOCKET)
return;
send_packet(SSH1_CMSG_EOF, PKT_END);
}
/*
* Set up the connection, login on the remote host and
* start execution of a command.
* Returns an error message, or NULL on success.
* (only used by pSCP)
*/
char *ssh_scp_init(char *host, int port, char *cmd, char **realhost)
{
char buf[160], *p;
assert(IS_SCP);
#ifdef MSCRYPTOAPI
if (crypto_startup() == 0)
return "Microsoft high encryption pack not installed!";
#endif
p = connect_to_host(host, port, realhost);
if (p != NULL)
return p;
random_init();
if (!do_ssh_init())
return "Protocol initialisation error";
/* Exchange keys and login */
do {
get_packet();
if (s == INVALID_SOCKET)
return "Connection closed by remote host";
} while (!do_ssh1_login(NULL, 0, 1));
if (ssh_state == SSH_STATE_CLOSED) {
closesocket(s);
s = INVALID_SOCKET;
return "Session initialisation error";
}
/* Execute command */
sprintf(buf, "Sending command: %.100s", cmd);
logevent(buf);
send_packet(SSH1_CMSG_EXEC_CMD, PKT_STR, cmd, PKT_END);
return NULL;
}
Backend ssh_backend = {
ssh_init,
ssh_msg,
ssh_send,
ssh_size,
ssh_special
};