2 * Platform-independent bits of X11 forwarding.
14 #define GET_32BIT_LSB_FIRST(cp) \
15 (((unsigned long)(unsigned char)(cp)[0]) | \
16 ((unsigned long)(unsigned char)(cp)[1] << 8) | \
17 ((unsigned long)(unsigned char)(cp)[2] << 16) | \
18 ((unsigned long)(unsigned char)(cp)[3] << 24))
20 #define PUT_32BIT_LSB_FIRST(cp, value) ( \
21 (cp)[0] = (char)(value), \
22 (cp)[1] = (char)((value) >> 8), \
23 (cp)[2] = (char)((value) >> 16), \
24 (cp)[3] = (char)((value) >> 24) )
26 #define GET_16BIT_LSB_FIRST(cp) \
27 (((unsigned long)(unsigned char)(cp)[0]) | \
28 ((unsigned long)(unsigned char)(cp)[1] << 8))
30 #define PUT_16BIT_LSB_FIRST(cp, value) ( \
31 (cp)[0] = (char)(value), \
32 (cp)[1] = (char)((value) >> 8) )
34 #define GET_32BIT_MSB_FIRST(cp) \
35 (((unsigned long)(unsigned char)(cp)[0] << 24) | \
36 ((unsigned long)(unsigned char)(cp)[1] << 16) | \
37 ((unsigned long)(unsigned char)(cp)[2] << 8) | \
38 ((unsigned long)(unsigned char)(cp)[3]))
40 #define PUT_32BIT_MSB_FIRST(cp, value) ( \
41 (cp)[0] = (char)((value) >> 24), \
42 (cp)[1] = (char)((value) >> 16), \
43 (cp)[2] = (char)((value) >> 8), \
44 (cp)[3] = (char)(value) )
46 #define GET_16BIT_MSB_FIRST(cp) \
47 (((unsigned long)(unsigned char)(cp)[0] << 8) | \
48 ((unsigned long)(unsigned char)(cp)[1]))
50 #define PUT_16BIT_MSB_FIRST(cp, value) ( \
51 (cp)[0] = (char)((value) >> 8), \
52 (cp)[1] = (char)(value) )
54 #define GET_16BIT(endian, cp) \
55 (endian=='B' ? GET_16BIT_MSB_FIRST(cp) : GET_16BIT_LSB_FIRST(cp))
57 #define PUT_16BIT(endian, cp, val) \
58 (endian=='B' ? PUT_16BIT_MSB_FIRST(cp, val) : PUT_16BIT_LSB_FIRST(cp, val))
60 const char *const x11_authnames
[] = {
61 "", "MIT-MAGIC-COOKIE-1", "XDM-AUTHORIZATION-1"
66 unsigned char clientid
[6];
70 unsigned char fakedata
[64], realdata
[64];
71 int fakeproto
, realproto
;
77 const struct plug_function_table
*fn
;
78 /* the above variable absolutely *must* be the first in this structure */
79 unsigned char firstpkt
[12]; /* first X data packet */
82 unsigned char *auth_data
;
83 int data_read
, auth_plen
, auth_psize
, auth_dlen
, auth_dsize
;
85 int throttled
, throttle_override
;
86 unsigned long peer_ip
;
88 void *c
; /* data used by ssh.c */
92 static int xdmseen_cmp(void *a
, void *b
)
94 struct XDMSeen
*sa
= a
, *sb
= b
;
95 return sa
->time
> sb
->time ?
1 :
96 sa
->time
< sb
->time ?
-1 :
97 memcmp(sa
->clientid
, sb
->clientid
, sizeof(sa
->clientid
));
100 void *x11_invent_auth(char *proto
, int protomaxlen
,
101 char *data
, int datamaxlen
, int proto_id
)
103 struct X11Auth
*auth
= snew(struct X11Auth
);
107 if (proto_id
== X11_MIT
) {
108 auth
->fakeproto
= X11_MIT
;
110 /* MIT-MAGIC-COOKIE-1. Cookie size is 128 bits (16 bytes). */
112 for (i
= 0; i
< 16; i
++)
113 auth
->fakedata
[i
] = random_byte();
114 auth
->xdmseen
= NULL
;
116 assert(proto_id
== X11_XDM
);
117 auth
->fakeproto
= X11_XDM
;
119 /* XDM-AUTHORIZATION-1. Cookie size is 16 bytes; byte 8 is zero. */
121 for (i
= 0; i
< 16; i
++)
122 auth
->fakedata
[i
] = (i
== 8 ?
0 : random_byte());
123 auth
->xdmseen
= newtree234(xdmseen_cmp
);
126 /* Now format for the recipient. */
127 strncpy(proto
, x11_authnames
[auth
->fakeproto
], protomaxlen
);
129 for (i
= 0; i
< auth
->fakelen
; i
++)
130 sprintf(ourdata
+ strlen(ourdata
), "%02x", auth
->fakedata
[i
]);
131 strncpy(data
, ourdata
, datamaxlen
);
136 void x11_free_auth(void *authv
)
138 struct X11Auth
*auth
= (struct X11Auth
*)authv
;
139 struct XDMSeen
*seen
;
141 if (auth
->xdmseen
!= NULL
) {
142 while ((seen
= delpos234(auth
->xdmseen
, 0)) != NULL
)
144 freetree234(auth
->xdmseen
);
150 * Fetch the real auth data for a given display string, and store
151 * it in an X11Auth structure. Returns NULL on success, or an error
154 void x11_get_real_auth(void *authv
, char *display
)
156 struct X11Auth
*auth
= (struct X11Auth
*)authv
;
158 auth
->realproto
= X11_NO_AUTH
; /* in case next call does nothing */
160 auth
->reallen
= sizeof(auth
->realdata
);
161 platform_get_x11_auth(display
, &auth
->realproto
,
162 auth
->realdata
, &auth
->reallen
);
165 #define XDM_MAXSKEW 20*60 /* 20 minute clock skew should be OK */
167 static char *x11_verify(unsigned long peer_ip
, int peer_port
,
168 struct X11Auth
*auth
, char *proto
,
169 unsigned char *data
, int dlen
)
171 if (strcmp(proto
, x11_authnames
[auth
->fakeproto
]) != 0)
172 return "wrong authentication protocol attempted";
173 if (auth
->fakeproto
== X11_MIT
) {
174 if (dlen
!= auth
->fakelen
)
175 return "MIT-MAGIC-COOKIE-1 data was wrong length";
176 if (memcmp(auth
->fakedata
, data
, dlen
) != 0)
177 return "MIT-MAGIC-COOKIE-1 data did not match";
179 if (auth
->fakeproto
== X11_XDM
) {
183 struct XDMSeen
*seen
, *ret
;
186 return "XDM-AUTHORIZATION-1 data was wrong length";
188 return "cannot do XDM-AUTHORIZATION-1 without remote address data";
189 des_decrypt_xdmauth(auth
->fakedata
+9, data
, 24);
190 if (memcmp(auth
->fakedata
, data
, 8) != 0)
191 return "XDM-AUTHORIZATION-1 data failed check"; /* cookie wrong */
192 if (GET_32BIT_MSB_FIRST(data
+8) != peer_ip
)
193 return "XDM-AUTHORIZATION-1 data failed check"; /* IP wrong */
194 if ((int)GET_16BIT_MSB_FIRST(data
+12) != peer_port
)
195 return "XDM-AUTHORIZATION-1 data failed check"; /* port wrong */
196 t
= GET_32BIT_MSB_FIRST(data
+14);
197 for (i
= 18; i
< 24; i
++)
198 if (data
[i
] != 0) /* zero padding wrong */
199 return "XDM-AUTHORIZATION-1 data failed check";
201 if (abs(t
- tim
) > XDM_MAXSKEW
)
202 return "XDM-AUTHORIZATION-1 time stamp was too far out";
203 seen
= snew(struct XDMSeen
);
205 memcpy(seen
->clientid
, data
+8, 6);
206 assert(auth
->xdmseen
!= NULL
);
207 ret
= add234(auth
->xdmseen
, seen
);
210 return "XDM-AUTHORIZATION-1 data replayed";
212 /* While we're here, purge entries too old to be replayed. */
214 seen
= index234(auth
->xdmseen
, 0);
215 assert(seen
!= NULL
);
216 if (t
- seen
->time
<= XDM_MAXSKEW
)
218 sfree(delpos234(auth
->xdmseen
, 0));
221 /* implement other protocols here if ever required */
225 static void x11_log(Plug p
, int type
, SockAddr addr
, int port
,
226 const char *error_msg
, int error_code
)
228 /* We have no interface to the logging module here, so we drop these. */
231 static int x11_closing(Plug plug
, const char *error_msg
, int error_code
,
234 struct X11Private
*pr
= (struct X11Private
*) plug
;
237 * We have no way to communicate down the forwarded connection,
238 * so if an error occurred on the socket, we just ignore it
239 * and treat it like a proper close.
246 static int x11_receive(Plug plug
, int urgent
, char *data
, int len
)
248 struct X11Private
*pr
= (struct X11Private
*) plug
;
250 if (sshfwd_write(pr
->c
, data
, len
) > 0) {
252 sk_set_frozen(pr
->s
, 1);
258 static void x11_sent(Plug plug
, int bufsize
)
260 struct X11Private
*pr
= (struct X11Private
*) plug
;
262 sshfwd_unthrottle(pr
->c
, bufsize
);
266 * When setting up X forwarding, we should send the screen number
267 * from the specified local display. This function extracts it from
268 * the display string.
270 int x11_get_screen_number(char *display
)
274 n
= strcspn(display
, ":");
277 n
= strcspn(display
, ".");
280 return atoi(display
+ n
+ 1);
283 /* Find the right display, returns an allocated string */
284 char *x11_display(const char *display
) {
286 if(!display
|| !*display
) {
287 /* try to find platform-specific local display */
288 if((ret
= platform_get_x_display())==0)
289 /* plausible default for all platforms */
292 ret
= dupstr(display
);
294 /* no transport specified, use whatever we think is best */
295 char *s
= dupcat(platform_x11_best_transport
, ret
, (char *)0);
303 * Called to set up the raw connection.
305 * Returns an error message, or NULL on success.
306 * also, fills the SocketsStructure
308 const char *x11_init(Socket
* s
, char *display
, void *c
, void *auth
,
309 const char *peeraddr
, int peerport
, const Config
*cfg
)
311 static const struct plug_function_table fn_table
= {
322 char *dummy_realhost
;
325 struct X11Private
*pr
;
327 /* default display */
328 display
= x11_display(display
);
330 * Split up display name into host and display-number parts.
332 n
= strcspn(display
, ":");
333 assert(n
!= 0); /* x11_display() promises this */
335 displaynum
= atoi(display
+ n
+ 1);
337 displaynum
= 0; /* sensible default */
338 if (n
> sizeof(host
) - 1)
339 n
= sizeof(host
) - 1;
340 strncpy(host
, display
, n
);
344 if(!strcmp(host
, "unix")) {
345 /* use AF_UNIX sockets (doesn't make sense on all platforms) */
346 addr
= platform_get_x11_unix_address(displaynum
,
348 port
= 0; /* to show we are not confused */
350 port
= 6000 + displaynum
;
355 addr
= name_lookup(host
, port
, &dummy_realhost
, cfg
, ADDRTYPE_UNSPEC
);
356 if ((err
= sk_addr_error(addr
)) != NULL
) {
365 pr
= snew(struct X11Private
);
367 pr
->auth_protocol
= NULL
;
368 pr
->auth
= (struct X11Auth
*)auth
;
371 pr
->throttled
= pr
->throttle_override
= 0;
374 pr
->s
= *s
= new_connection(addr
, dummy_realhost
, port
,
375 0, 1, 0, 0, (Plug
) pr
, cfg
);
376 if ((err
= sk_socket_error(*s
)) != NULL
) {
382 * See if we can make sense of the peer address we were given.
387 4 == sscanf(peeraddr
, "%d.%d.%d.%d", i
+0, i
+1, i
+2, i
+3)) {
388 pr
->peer_ip
= (i
[0] << 24) | (i
[1] << 16) | (i
[2] << 8) | i
[3];
389 pr
->peer_port
= peerport
;
396 sk_set_private_ptr(*s
, pr
);
400 void x11_close(Socket s
)
402 struct X11Private
*pr
;
405 pr
= (struct X11Private
*) sk_get_private_ptr(s
);
406 if (pr
->auth_protocol
) {
407 sfree(pr
->auth_protocol
);
408 sfree(pr
->auth_data
);
416 void x11_unthrottle(Socket s
)
418 struct X11Private
*pr
;
421 pr
= (struct X11Private
*) sk_get_private_ptr(s
);
424 sk_set_frozen(s
, pr
->throttled
|| pr
->throttle_override
);
427 void x11_override_throttle(Socket s
, int enable
)
429 struct X11Private
*pr
;
432 pr
= (struct X11Private
*) sk_get_private_ptr(s
);
434 pr
->throttle_override
= enable
;
435 sk_set_frozen(s
, pr
->throttled
|| pr
->throttle_override
);
439 * Called to send data down the raw connection.
441 int x11_send(Socket s
, char *data
, int len
)
443 struct X11Private
*pr
;
446 pr
= (struct X11Private
*) sk_get_private_ptr(s
);
449 * Read the first packet.
451 while (len
> 0 && pr
->data_read
< 12)
452 pr
->firstpkt
[pr
->data_read
++] = (unsigned char) (len
--, *data
++);
453 if (pr
->data_read
< 12)
457 * If we have not allocated the auth_protocol and auth_data
458 * strings, do so now.
460 if (!pr
->auth_protocol
) {
461 pr
->auth_plen
= GET_16BIT(pr
->firstpkt
[0], pr
->firstpkt
+ 6);
462 pr
->auth_dlen
= GET_16BIT(pr
->firstpkt
[0], pr
->firstpkt
+ 8);
463 pr
->auth_psize
= (pr
->auth_plen
+ 3) & ~3;
464 pr
->auth_dsize
= (pr
->auth_dlen
+ 3) & ~3;
465 /* Leave room for a terminating zero, to make our lives easier. */
466 pr
->auth_protocol
= snewn(pr
->auth_psize
+ 1, char);
467 pr
->auth_data
= snewn(pr
->auth_dsize
, unsigned char);
471 * Read the auth_protocol and auth_data strings.
473 while (len
> 0 && pr
->data_read
< 12 + pr
->auth_psize
)
474 pr
->auth_protocol
[pr
->data_read
++ - 12] = (len
--, *data
++);
475 while (len
> 0 && pr
->data_read
< 12 + pr
->auth_psize
+ pr
->auth_dsize
)
476 pr
->auth_data
[pr
->data_read
++ - 12 -
477 pr
->auth_psize
] = (unsigned char) (len
--, *data
++);
478 if (pr
->data_read
< 12 + pr
->auth_psize
+ pr
->auth_dsize
)
482 * If we haven't verified the authentication, do so now.
487 pr
->auth_protocol
[pr
->auth_plen
] = '\0'; /* ASCIZ */
488 err
= x11_verify(pr
->peer_ip
, pr
->peer_port
,
489 pr
->auth
, pr
->auth_protocol
,
490 pr
->auth_data
, pr
->auth_dlen
);
493 * If authentication failed, construct and send an error
494 * packet, then terminate the connection.
499 unsigned char *reply
;
501 message
= dupprintf("PuTTY X11 proxy: %s", err
);
502 msglen
= strlen(message
);
503 reply
= snewn(8 + msglen
+1 + 4, unsigned char); /* include zero */
504 msgsize
= (msglen
+ 3) & ~3;
505 reply
[0] = 0; /* failure */
506 reply
[1] = msglen
; /* length of reason string */
507 memcpy(reply
+ 2, pr
->firstpkt
+ 2, 4); /* major/minor proto vsn */
508 PUT_16BIT(pr
->firstpkt
[0], reply
+ 6, msgsize
>> 2);/* data len */
509 memset(reply
+ 8, 0, msgsize
);
510 memcpy(reply
+ 8, message
, msglen
);
511 sshfwd_write(pr
->c
, (char *)reply
, 8 + msgsize
);
520 * Now we know we're going to accept the connection. Strip
521 * the fake auth data, and optionally put real auth data in
525 char realauthdata
[64];
527 int authstrlen
= strlen(x11_authnames
[pr
->auth
->realproto
]);
529 static const char zeroes
[4] = { 0,0,0,0 };
532 if (pr
->auth
->realproto
== X11_MIT
) {
533 assert(pr
->auth
->reallen
<= lenof(realauthdata
));
534 realauthlen
= pr
->auth
->reallen
;
535 memcpy(realauthdata
, pr
->auth
->realdata
, realauthlen
);
536 } else if (pr
->auth
->realproto
== X11_XDM
&&
537 pr
->auth
->reallen
== 16 &&
538 ((buf
= sk_getxdmdata(s
, &buflen
))!=0)) {
540 realauthlen
= (buflen
+12+7) & ~7;
541 assert(realauthlen
<= lenof(realauthdata
));
542 memset(realauthdata
, 0, realauthlen
);
543 memcpy(realauthdata
, pr
->auth
->realdata
, 8);
544 memcpy(realauthdata
+8, buf
, buflen
);
546 PUT_32BIT_MSB_FIRST(realauthdata
+8+buflen
, t
);
547 des_encrypt_xdmauth(pr
->auth
->realdata
+9,
548 (unsigned char *)realauthdata
,
552 /* implement other auth methods here if required */
554 PUT_16BIT(pr
->firstpkt
[0], pr
->firstpkt
+ 6, authstrlen
);
555 PUT_16BIT(pr
->firstpkt
[0], pr
->firstpkt
+ 8, realauthlen
);
557 sk_write(s
, (char *)pr
->firstpkt
, 12);
560 sk_write(s
, x11_authnames
[pr
->auth
->realproto
], authstrlen
);
561 sk_write(s
, zeroes
, 3 & (-authstrlen
));
564 sk_write(s
, realauthdata
, realauthlen
);
565 sk_write(s
, zeroes
, 3 & (-realauthlen
));
572 * After initialisation, just copy data simply.
575 return sk_write(s
, data
, len
);