X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/c1f5f956448a2bd052e71ee1a57f48d9327f2741..8ce72d2c1c7651def2425be607ef623e6b0b9bd2:/ssh.c diff --git a/ssh.c b/ssh.c index 633453d6..d3df6bcb 100644 --- a/ssh.c +++ b/ssh.c @@ -13,6 +13,28 @@ #include "ssh.h" +#define SSH_MSG_DISCONNECT 1 +#define SSH_SMSG_PUBLIC_KEY 2 +#define SSH_CMSG_SESSION_KEY 3 +#define SSH_CMSG_USER 4 +#define SSH_CMSG_AUTH_PASSWORD 9 +#define SSH_CMSG_REQUEST_PTY 10 +#define SSH_CMSG_EXEC_SHELL 12 +#define SSH_CMSG_STDIN_DATA 16 +#define SSH_SMSG_STDOUT_DATA 17 +#define SSH_SMSG_STDERR_DATA 18 +#define SSH_SMSG_SUCCESS 14 +#define SSH_SMSG_FAILURE 15 +#define SSH_SMSG_EXITSTATUS 20 +#define SSH_MSG_IGNORE 32 +#define SSH_CMSG_EXIT_CONFIRMATION 33 +#define SSH_MSG_DEBUG 36 +#define SSH_CMSG_AUTH_TIS 39 +#define SSH_SMSG_AUTH_TIS_CHALLENGE 40 +#define SSH_CMSG_AUTH_TIS_RESPONSE 41 + +#define SSH_AUTH_TIS 5 + /* Coroutine mechanics for the sillier bits of the code */ #define crBegin1 static int crLine = 0; #define crBegin2 switch(crLine) { case 0:; @@ -47,7 +69,8 @@ static char *savedhost; static enum { SSH_STATE_BEFORE_SIZE, SSH_STATE_INTERMED, - SSH_STATE_SESSION + SSH_STATE_SESSION, + SSH_STATE_CLOSED } ssh_state = SSH_STATE_BEFORE_SIZE; static int size_needed = FALSE; @@ -75,7 +98,6 @@ static int s_read (char *buf, int len) { static void c_write (char *buf, int len) { while (len--) { int new_head = (inbuf_head + 1) & INBUF_MASK; - int c = (unsigned char) *buf; if (new_head != inbuf_reap) { inbuf[inbuf_head] = *buf++; inbuf_head = new_head; @@ -100,10 +122,8 @@ static void ssh_size(void); static void ssh_gotdata(unsigned char *data, int datalen) { static long len, biglen, to_read; - static unsigned char c, *p; + static unsigned char *p; static int i, pad; - static char padding[8]; - static unsigned char word[4]; crBegin; while (1) { @@ -156,8 +176,10 @@ static void ssh_gotdata(unsigned char *data, int datalen) { pktin.type = pktin.data[pad]; pktin.body = pktin.data+pad+1; - if (pktin.type == 36) { /* SSH_MSG_DEBUG */ + if (pktin.type == SSH_MSG_DEBUG) { /* FIXME: log it */ + } else if (pktin.type == SSH_MSG_IGNORE) { + /* do nothing */; } else ssh_protocol(NULL, 0, 1); } @@ -213,10 +235,26 @@ static void s_wrpkt(void) { s_write(pktout.data, biglen+4); } +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; +} + static int do_ssh_init(void) { - char c; + char c, *vsp; char version[10]; - char vstring[40]; + char vstring[80]; + char vlog[sizeof(vstring)+20]; int i; #ifdef FWHACK @@ -232,11 +270,15 @@ static int do_ssh_init(void) { 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'; @@ -248,8 +290,16 @@ static int do_ssh_init(void) { break; } - sprintf(vstring, "SSH-%s-7.7.7\n", - (strcmp(version, "1.5") <= 0 ? version : "1.5")); + *vsp = 0; + sprintf(vlog, "Server version: %s", vstring); + vlog[strcspn(vlog, "\r\n")] = '\0'; + logevent(vlog); + + 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); s_write(vstring, strlen(vstring)); return 1; } @@ -261,8 +311,12 @@ static void ssh_protocol(unsigned char *in, int inlen, int ispkt) { unsigned char cookie[8]; struct RSAKey servkey, hostkey; struct MD5Context md5c; + static unsigned long supported_ciphers_mask, supported_auths_mask; + int cipher_type; extern struct ssh_cipher ssh_3des; + extern struct ssh_cipher ssh_des; + extern struct ssh_cipher ssh_blowfish; crBegin; @@ -271,17 +325,48 @@ static void ssh_protocol(unsigned char *in, int inlen, int ispkt) { while (!ispkt) crReturnV; - if (pktin.type != 2) + if (pktin.type != SSH_SMSG_PUBLIC_KEY) fatalbox("Public key packet not received"); - memcpy(cookie, pktin.body, 8); + logevent("Received public keys"); - MD5Init(&md5c); + memcpy(cookie, pktin.body, 8); i = makekey(pktin.body+8, &servkey, &keystr1); j = makekey(pktin.body+8+i, &hostkey, &keystr2); + /* + * 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 = ((pktin.body[12+i+j] << 24) | + (pktin.body[13+i+j] << 16) | + (pktin.body[14+i+j] << 8) | + (pktin.body[15+i+j])); + + supported_auths_mask = ((pktin.body[16+i+j] << 24) | + (pktin.body[17+i+j] << 16) | + (pktin.body[18+i+j] << 8) | + (pktin.body[19+i+j])); + + MD5Init(&md5c); + MD5Update(&md5c, keystr2, hostkey.bytes); MD5Update(&md5c, keystr1, servkey.bytes); MD5Update(&md5c, pktin.body, 8); @@ -313,8 +398,23 @@ static void ssh_protocol(unsigned char *in, int inlen, int ispkt) { rsaencrypt(rsabuf, hostkey.bytes, &servkey); } - s_wrpkt_start(3, len+15); - pktout.body[0] = 3; /* SSH_CIPHER_3DES */ + 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; + } + + s_wrpkt_start(SSH_CMSG_SESSION_KEY, len+15); + pktout.body[0] = cipher_type; memcpy(pktout.body+1, cookie, 8); pktout.body[9] = (len*8) >> 8; pktout.body[10] = (len*8) & 0xFF; @@ -322,17 +422,22 @@ static void ssh_protocol(unsigned char *in, int inlen, int ispkt) { pktout.body[len+11] = pktout.body[len+12] = 0; /* protocol flags */ pktout.body[len+13] = pktout.body[len+14] = 0; s_wrpkt(); + logevent("Trying to enable encryption..."); free(rsabuf); - cipher = &ssh_3des; + cipher = cipher_type == SSH_CIPHER_BLOWFISH ? &ssh_blowfish : + cipher_type == SSH_CIPHER_DES ? &ssh_des : + &ssh_3des; cipher->sesskey(session_key); do { crReturnV; } while (!ispkt); - if (pktin.type != 14) + if (pktin.type != SSH_SMSG_SUCCESS) fatalbox("Encryption not successfully enabled"); + logevent("Successfully started encryption"); + fflush(stdout); { static char username[100]; @@ -380,7 +485,12 @@ static void ssh_protocol(unsigned char *in, int inlen, int ispkt) { sprintf(stuff, "Sent username \"%s\".\r\n", username); c_write(stuff, strlen(stuff)); } - s_wrpkt_start(4, 4+strlen(username)); + s_wrpkt_start(SSH_CMSG_USER, 4+strlen(username)); + { + char userlog[20+sizeof(username)]; + sprintf(userlog, "Sent username \"%s\"", username); + logevent(userlog); + } pktout.body[0] = pktout.body[1] = pktout.body[2] = 0; pktout.body[3] = strlen(username); memcpy(pktout.body+4, username, strlen(username)); @@ -389,11 +499,40 @@ static void ssh_protocol(unsigned char *in, int inlen, int ispkt) { do { crReturnV; } while (!ispkt); - while (pktin.type == 15) { + while (pktin.type == SSH_SMSG_FAILURE) { static char password[100]; static int pos; static char c; - c_write("password: ", 10); + static int pwpkt_type; + + /* + * Show password prompt, having first obtained it via a TIS + * exchange if we're doing TIS authentication. + */ + pwpkt_type = SSH_CMSG_AUTH_PASSWORD; + if (pktin.type == SSH_SMSG_FAILURE && + cfg.try_tis_auth && + (supported_auths_mask & (1<= 0) { do { crReturnV; } while (ispkt); @@ -420,23 +559,27 @@ static void ssh_protocol(unsigned char *in, int inlen, int ispkt) { } } c_write("\r\n", 2); - s_wrpkt_start(9, 4+strlen(password)); + s_wrpkt_start(pwpkt_type, 4+strlen(password)); pktout.body[0] = pktout.body[1] = pktout.body[2] = 0; pktout.body[3] = strlen(password); memcpy(pktout.body+4, password, strlen(password)); s_wrpkt(); + logevent("Sent password"); memset(password, 0, strlen(password)); do { crReturnV; } while (!ispkt); if (pktin.type == 15) { c_write("Access denied\r\n", 15); + logevent("Authentication refused"); } else if (pktin.type != 14) { fatalbox("Strange packet received, type %d", pktin.type); } } + logevent("Authentication successful"); + if (!cfg.nopty) { i = strlen(cfg.termtype); - s_wrpkt_start(10, i+5*4+1); + s_wrpkt_start(SSH_CMSG_REQUEST_PTY, i+5*4+1); pktout.body[0] = (i >> 24) & 0xFF; pktout.body[1] = (i >> 16) & 0xFF; pktout.body[2] = (i >> 8) & 0xFF; @@ -455,15 +598,17 @@ static void ssh_protocol(unsigned char *in, int inlen, int ispkt) { s_wrpkt(); ssh_state = SSH_STATE_INTERMED; do { crReturnV; } while (!ispkt); - if (pktin.type != 14 && pktin.type != 15) { + if (pktin.type != SSH_SMSG_SUCCESS && pktin.type != SSH_SMSG_FAILURE) { fatalbox("Protocol confusion"); - } else if (pktin.type == 15) { + } else if (pktin.type == SSH_SMSG_FAILURE) { c_write("Server refused to allocate pty\r\n", 32); } + logevent("Allocated pty"); } - s_wrpkt_start(12, 0); + s_wrpkt_start(SSH_CMSG_EXEC_SHELL, 0); s_wrpkt(); + logevent("Started session"); ssh_state = SSH_STATE_SESSION; if (size_needed) @@ -472,27 +617,28 @@ static void ssh_protocol(unsigned char *in, int inlen, int ispkt) { while (1) { crReturnV; if (ispkt) { - if (pktin.type == 17 || pktin.type == 18) { + if (pktin.type == SSH_SMSG_STDOUT_DATA || + pktin.type == SSH_SMSG_STDERR_DATA) { long len = 0; for (i = 0; i < 4; i++) len = (len << 8) + pktin.body[i]; c_write(pktin.body+4, len); - } else if (pktin.type == 1) { - /* SSH_MSG_DISCONNECT: do nothing */ - } else if (pktin.type == 14) { - /* SSH_MSG_SUCCESS: may be from EXEC_SHELL on some servers */ - } else if (pktin.type == 15) { - /* SSH_MSG_FAILURE: may be from EXEC_SHELL on some servers + } else if (pktin.type == SSH_MSG_DISCONNECT) { + ssh_state = SSH_STATE_CLOSED; + logevent("Received disconnect request"); + } else if (pktin.type == SSH_SMSG_SUCCESS) { + /* may be from EXEC_SHELL on some servers */ + } else if (pktin.type == SSH_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 == 20) { - /* EXITSTATUS */ - s_wrpkt_start(33, 0); + } else if (pktin.type == SSH_SMSG_EXITSTATUS) { + s_wrpkt_start(SSH_CMSG_EXIT_CONFIRMATION, 0); s_wrpkt(); } else { fatalbox("Strange packet received: type %d", pktin.type); } } else { - s_wrpkt_start(16, 4+inlen); + s_wrpkt_start(SSH_CMSG_STDIN_DATA, 4+inlen); pktout.body[0] = (inlen >> 24) & 0xFF; pktout.body[1] = (inlen >> 16) & 0xFF; pktout.body[2] = (inlen >> 8) & 0xFF; @@ -626,14 +772,22 @@ static int ssh_msg (WPARAM wParam, LPARAM lParam) { int ret; char buf[256]; - if (s == INVALID_SOCKET) /* how the hell did we get here?! */ - return -5000; + /* + * 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; @@ -641,13 +795,10 @@ static int ssh_msg (WPARAM wParam, LPARAM lParam) { return -10000-WSAGetLastError(); if (ret == 0) { s = INVALID_SOCKET; - return 0; /* can't happen, in theory */ + return 0; } ssh_gotdata (buf, ret); return 1; - case FD_CLOSE: - s = INVALID_SOCKET; - return 0; } return 1; /* shouldn't happen, but WTF */ } @@ -668,6 +819,7 @@ static void ssh_send (char *buf, int len) { static void ssh_size(void) { switch (ssh_state) { case SSH_STATE_BEFORE_SIZE: + case SSH_STATE_CLOSED: break; /* do nothing */ case SSH_STATE_INTERMED: size_needed = TRUE; /* buffer for later */