X forwarding authentication is now invented on a per-SSH-connection
[u/mdw/putty] / x11fwd.c
CommitLineData
9c964e85 1#include <windows.h>
2#include <stdio.h>
3#include <stdlib.h>
4
5#include "putty.h"
6#include "ssh.h"
7
9c964e85 8#define GET_32BIT_LSB_FIRST(cp) \
9 (((unsigned long)(unsigned char)(cp)[0]) | \
10 ((unsigned long)(unsigned char)(cp)[1] << 8) | \
11 ((unsigned long)(unsigned char)(cp)[2] << 16) | \
12 ((unsigned long)(unsigned char)(cp)[3] << 24))
13
14#define PUT_32BIT_LSB_FIRST(cp, value) ( \
15 (cp)[0] = (value), \
16 (cp)[1] = (value) >> 8, \
17 (cp)[2] = (value) >> 16, \
18 (cp)[3] = (value) >> 24 )
19
20#define GET_16BIT_LSB_FIRST(cp) \
21 (((unsigned long)(unsigned char)(cp)[0]) | \
22 ((unsigned long)(unsigned char)(cp)[1] << 8))
23
24#define PUT_16BIT_LSB_FIRST(cp, value) ( \
25 (cp)[0] = (value), \
26 (cp)[1] = (value) >> 8 )
27
28#define GET_32BIT_MSB_FIRST(cp) \
29 (((unsigned long)(unsigned char)(cp)[0] << 24) | \
30 ((unsigned long)(unsigned char)(cp)[1] << 16) | \
31 ((unsigned long)(unsigned char)(cp)[2] << 8) | \
32 ((unsigned long)(unsigned char)(cp)[3]))
33
34#define PUT_32BIT_MSB_FIRST(cp, value) ( \
35 (cp)[0] = (value) >> 24, \
36 (cp)[1] = (value) >> 16, \
37 (cp)[2] = (value) >> 8, \
38 (cp)[3] = (value) )
39
40#define GET_16BIT_MSB_FIRST(cp) \
41 (((unsigned long)(unsigned char)(cp)[0] << 8) | \
42 ((unsigned long)(unsigned char)(cp)[1]))
43
44#define PUT_16BIT_MSB_FIRST(cp, value) ( \
45 (cp)[0] = (value) >> 8, \
46 (cp)[1] = (value) )
47
48#define GET_16BIT(endian, cp) \
49 (endian=='B' ? GET_16BIT_MSB_FIRST(cp) : GET_16BIT_LSB_FIRST(cp))
50
51#define PUT_16BIT(endian, cp, val) \
52 (endian=='B' ? PUT_16BIT_MSB_FIRST(cp, val) : PUT_16BIT_LSB_FIRST(cp, val))
53
302121de 54struct X11Auth {
55 unsigned char data[64];
56 int len;
57};
58
9c964e85 59struct X11Private {
302121de 60 const struct plug_function_table *fn;
7e78000d 61 /* the above variable absolutely *must* be the first in this structure */
32874aea 62 unsigned char firstpkt[12]; /* first X data packet */
302121de 63 struct X11Auth *auth;
9c964e85 64 char *auth_protocol;
65 unsigned char *auth_data;
66 int data_read, auth_plen, auth_psize, auth_dlen, auth_dsize;
67 int verified;
5471d09a 68 int throttled, throttle_override;
32874aea 69 void *c; /* data used by ssh.c */
7e78000d 70 Socket s;
9c964e85 71};
72
32874aea 73void x11_close(Socket s);
9c964e85 74
302121de 75void *x11_invent_auth(char *proto, int protomaxlen,
32874aea 76 char *data, int datamaxlen)
77{
302121de 78 struct X11Auth *auth = smalloc(sizeof(struct X11Auth));
9c964e85 79 char ourdata[64];
80 int i;
81
82 /* MIT-MAGIC-COOKIE-1. Cookie size is 128 bits (16 bytes). */
302121de 83 auth->len = 16;
9c964e85 84 for (i = 0; i < 16; i++)
302121de 85 auth->data[i] = random_byte();
9c964e85 86
87 /* Now format for the recipient. */
88 strncpy(proto, "MIT-MAGIC-COOKIE-1", protomaxlen);
89 ourdata[0] = '\0';
302121de 90 for (i = 0; i < auth->len; i++)
91 sprintf(ourdata + strlen(ourdata), "%02x", auth->data[i]);
9c964e85 92 strncpy(data, ourdata, datamaxlen);
302121de 93
94 return auth;
9c964e85 95}
96
302121de 97static int x11_verify(struct X11Auth *auth,
98 char *proto, unsigned char *data, int dlen)
32874aea 99{
9c964e85 100 if (strcmp(proto, "MIT-MAGIC-COOKIE-1") != 0)
32874aea 101 return 0; /* wrong protocol attempted */
302121de 102 if (dlen != auth->len)
32874aea 103 return 0; /* cookie was wrong length */
302121de 104 if (memcmp(auth->data, data, dlen) != 0)
32874aea 105 return 0; /* cookie was wrong cookie! */
9c964e85 106 return 1;
107}
108
32874aea 109static int x11_closing(Plug plug, char *error_msg, int error_code,
110 int calling_back)
111{
7e78000d 112 struct X11Private *pr = (struct X11Private *) plug;
113
114 /*
115 * We have no way to communicate down the forwarded connection,
116 * so if an error occurred on the socket, we just ignore it
117 * and treat it like a proper close.
118 */
119 sshfwd_close(pr->c);
120 x11_close(pr->s);
121 return 1;
122}
123
32874aea 124static int x11_receive(Plug plug, int urgent, char *data, int len)
125{
7e78000d 126 struct X11Private *pr = (struct X11Private *) plug;
9c964e85 127
5471d09a 128 if (sshfwd_write(pr->c, data, len) > 0) {
129 pr->throttled = 1;
130 sk_set_frozen(pr->s, 1);
131 }
132
9c964e85 133 return 1;
134}
135
5471d09a 136static void x11_sent(Plug plug, int bufsize)
137{
138 struct X11Private *pr = (struct X11Private *) plug;
139
140 sshfwd_unthrottle(pr->c, bufsize);
141}
142
9c964e85 143/*
144 * Called to set up the raw connection.
145 *
146 * Returns an error message, or NULL on success.
147 * also, fills the SocketsStructure
9c964e85 148 */
302121de 149char *x11_init(Socket * s, char *display, void *c, void *auth)
32874aea 150{
302121de 151 static const struct plug_function_table fn_table = {
7e78000d 152 x11_closing,
5471d09a 153 x11_receive,
154 x11_sent,
155 NULL
7e78000d 156 };
157
9c964e85 158 SockAddr addr;
159 int port;
0c6c9a70 160 char *err, *dummy_realhost;
9c964e85 161 char host[128];
162 int n, displaynum;
163 struct X11Private *pr;
164
165 /*
166 * Split up display name into host and display-number parts.
167 */
168 n = strcspn(display, ":");
169 if (display[n])
32874aea 170 displaynum = atoi(display + n + 1);
9c964e85 171 else
32874aea 172 displaynum = 0; /* sensible default */
173 if (n > sizeof(host) - 1)
174 n = sizeof(host) - 1;
9c964e85 175 strncpy(host, display, n);
176 host[n] = '\0';
177
178 /*
179 * Try to find host.
180 */
0c6c9a70 181 addr = sk_namelookup(host, &dummy_realhost);
32874aea 182 if ((err = sk_addr_error(addr)))
9c964e85 183 return err;
184
185 port = 6000 + displaynum;
186
187 /*
188 * Open socket.
189 */
32874aea 190 pr = (struct X11Private *) smalloc(sizeof(struct X11Private));
7e78000d 191 pr->fn = &fn_table;
9c964e85 192 pr->auth_protocol = NULL;
302121de 193 pr->auth = (struct X11Auth *)auth;
9c964e85 194 pr->verified = 0;
195 pr->data_read = 0;
5471d09a 196 pr->throttled = pr->throttle_override = 0;
9c964e85 197 pr->c = c;
198
8eebd221 199 pr->s = *s = new_connection(addr, dummy_realhost, port, 0, 1, 0, (Plug) pr);
32874aea 200 if ((err = sk_socket_error(*s))) {
201 sfree(pr);
7e78000d 202 return err;
203 }
204
9c964e85 205 sk_set_private_ptr(*s, pr);
206 sk_addr_free(addr);
207 return NULL;
208}
209
32874aea 210void x11_close(Socket s)
211{
212 struct X11Private *pr;
d74d141c 213 if (!s)
214 return;
215 pr = (struct X11Private *) sk_get_private_ptr(s);
9c964e85 216 if (pr->auth_protocol) {
32874aea 217 sfree(pr->auth_protocol);
218 sfree(pr->auth_data);
9c964e85 219 }
220
221 sfree(pr);
222
223 sk_close(s);
224}
225
5471d09a 226void x11_unthrottle(Socket s)
227{
228 struct X11Private *pr;
229 if (!s)
230 return;
231 pr = (struct X11Private *) sk_get_private_ptr(s);
232
233 pr->throttled = 0;
234 sk_set_frozen(s, pr->throttled || pr->throttle_override);
235}
236
237void x11_override_throttle(Socket s, int enable)
238{
239 struct X11Private *pr;
240 if (!s)
241 return;
242 pr = (struct X11Private *) sk_get_private_ptr(s);
243
244 pr->throttle_override = enable;
245 sk_set_frozen(s, pr->throttled || pr->throttle_override);
246}
247
9c964e85 248/*
249 * Called to send data down the raw connection.
250 */
5471d09a 251int x11_send(Socket s, char *data, int len)
32874aea 252{
253 struct X11Private *pr = (struct X11Private *) sk_get_private_ptr(s);
9c964e85 254
255 if (s == NULL)
5471d09a 256 return 0;
9c964e85 257
258 /*
259 * Read the first packet.
260 */
261 while (len > 0 && pr->data_read < 12)
32874aea 262 pr->firstpkt[pr->data_read++] = (unsigned char) (len--, *data++);
9c964e85 263 if (pr->data_read < 12)
5471d09a 264 return 0;
9c964e85 265
266 /*
267 * If we have not allocated the auth_protocol and auth_data
268 * strings, do so now.
269 */
270 if (!pr->auth_protocol) {
32874aea 271 pr->auth_plen = GET_16BIT(pr->firstpkt[0], pr->firstpkt + 6);
272 pr->auth_dlen = GET_16BIT(pr->firstpkt[0], pr->firstpkt + 8);
273 pr->auth_psize = (pr->auth_plen + 3) & ~3;
274 pr->auth_dsize = (pr->auth_dlen + 3) & ~3;
275 /* Leave room for a terminating zero, to make our lives easier. */
276 pr->auth_protocol = (char *) smalloc(pr->auth_psize + 1);
277 pr->auth_data = (char *) smalloc(pr->auth_dsize);
9c964e85 278 }
279
280 /*
281 * Read the auth_protocol and auth_data strings.
282 */
283 while (len > 0 && pr->data_read < 12 + pr->auth_psize)
32874aea 284 pr->auth_protocol[pr->data_read++ - 12] = (len--, *data++);
9c964e85 285 while (len > 0 && pr->data_read < 12 + pr->auth_psize + pr->auth_dsize)
32874aea 286 pr->auth_data[pr->data_read++ - 12 -
287 pr->auth_psize] = (unsigned char) (len--, *data++);
9c964e85 288 if (pr->data_read < 12 + pr->auth_psize + pr->auth_dsize)
5471d09a 289 return 0;
9c964e85 290
291 /*
292 * If we haven't verified the authentication, do so now.
293 */
294 if (!pr->verified) {
32874aea 295 int ret;
296
297 pr->auth_protocol[pr->auth_plen] = '\0'; /* ASCIZ */
302121de 298 ret = x11_verify(pr->auth, pr->auth_protocol,
299 pr->auth_data, pr->auth_dlen);
32874aea 300
301 /*
302 * If authentication failed, construct and send an error
303 * packet, then terminate the connection.
304 */
305 if (!ret) {
306 char message[] = "Authentication failed at PuTTY X11 proxy";
307 unsigned char reply[8 + sizeof(message) + 4];
308 int msglen = sizeof(message) - 1; /* skip zero byte */
309 int msgsize = (msglen + 3) & ~3;
310 reply[0] = 0; /* failure */
311 reply[1] = msglen; /* length of reason string */
312 memcpy(reply + 2, pr->firstpkt + 2, 4); /* major/minor proto vsn */
75105663 313 PUT_16BIT(pr->firstpkt[0], reply + 6, msgsize >> 2);/* data len */
32874aea 314 memset(reply + 8, 0, msgsize);
315 memcpy(reply + 8, message, msglen);
316 sshfwd_write(pr->c, reply, 8 + msgsize);
317 sshfwd_close(pr->c);
318 x11_close(s);
5471d09a 319 return 0;
32874aea 320 }
321
322 /*
323 * Now we know we're going to accept the connection. Strip
324 * the auth data. (TODO: if we ever work out how, we should
325 * replace some real auth data in here.)
326 */
327 PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 6, 0); /* auth proto */
328 PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 8, 0); /* auth data */
329 sk_write(s, pr->firstpkt, 12);
330 pr->verified = 1;
9c964e85 331 }
332
333 /*
334 * After initialisation, just copy data simply.
335 */
336
5471d09a 337 return sk_write(s, data, len);
9c964e85 338}