| 1 | /* |
| 2 | * Platform-independent bits of X11 forwarding. |
| 3 | */ |
| 4 | |
| 5 | #include <stdio.h> |
| 6 | #include <stdlib.h> |
| 7 | #include <assert.h> |
| 8 | #include <time.h> |
| 9 | |
| 10 | #include "putty.h" |
| 11 | #include "ssh.h" |
| 12 | #include "tree234.h" |
| 13 | |
| 14 | #define GET_16BIT(endian, cp) \ |
| 15 | (endian=='B' ? GET_16BIT_MSB_FIRST(cp) : GET_16BIT_LSB_FIRST(cp)) |
| 16 | |
| 17 | #define PUT_16BIT(endian, cp, val) \ |
| 18 | (endian=='B' ? PUT_16BIT_MSB_FIRST(cp, val) : PUT_16BIT_LSB_FIRST(cp, val)) |
| 19 | |
| 20 | const char *const x11_authnames[] = { |
| 21 | "", "MIT-MAGIC-COOKIE-1", "XDM-AUTHORIZATION-1" |
| 22 | }; |
| 23 | |
| 24 | struct XDMSeen { |
| 25 | unsigned int time; |
| 26 | unsigned char clientid[6]; |
| 27 | }; |
| 28 | |
| 29 | struct X11Private { |
| 30 | const struct plug_function_table *fn; |
| 31 | /* the above variable absolutely *must* be the first in this structure */ |
| 32 | unsigned char firstpkt[12]; /* first X data packet */ |
| 33 | struct X11Display *disp; |
| 34 | char *auth_protocol; |
| 35 | unsigned char *auth_data; |
| 36 | int data_read, auth_plen, auth_psize, auth_dlen, auth_dsize; |
| 37 | int verified; |
| 38 | int throttled, throttle_override; |
| 39 | unsigned long peer_ip; |
| 40 | int peer_port; |
| 41 | void *c; /* data used by ssh.c */ |
| 42 | Socket s; |
| 43 | }; |
| 44 | |
| 45 | static int xdmseen_cmp(void *a, void *b) |
| 46 | { |
| 47 | struct XDMSeen *sa = a, *sb = b; |
| 48 | return sa->time > sb->time ? 1 : |
| 49 | sa->time < sb->time ? -1 : |
| 50 | memcmp(sa->clientid, sb->clientid, sizeof(sa->clientid)); |
| 51 | } |
| 52 | |
| 53 | /* Do-nothing "plug" implementation, used by x11_setup_display() when it |
| 54 | * creates a trial connection (and then immediately closes it). |
| 55 | * XXX: bit out of place here, could in principle live in a platform- |
| 56 | * independent network.c or something */ |
| 57 | static void dummy_plug_log(Plug p, int type, SockAddr addr, int port, |
| 58 | const char *error_msg, int error_code) { } |
| 59 | static int dummy_plug_closing |
| 60 | (Plug p, const char *error_msg, int error_code, int calling_back) |
| 61 | { return 1; } |
| 62 | static int dummy_plug_receive(Plug p, int urgent, char *data, int len) |
| 63 | { return 1; } |
| 64 | static void dummy_plug_sent(Plug p, int bufsize) { } |
| 65 | static int dummy_plug_accepting(Plug p, OSSocket sock) { return 1; } |
| 66 | static const struct plug_function_table dummy_plug = { |
| 67 | dummy_plug_log, dummy_plug_closing, dummy_plug_receive, |
| 68 | dummy_plug_sent, dummy_plug_accepting |
| 69 | }; |
| 70 | |
| 71 | struct X11Display *x11_setup_display(char *display, int authtype, Conf *conf) |
| 72 | { |
| 73 | struct X11Display *disp = snew(struct X11Display); |
| 74 | char *localcopy; |
| 75 | int i; |
| 76 | |
| 77 | if (!display || !*display) { |
| 78 | localcopy = platform_get_x_display(); |
| 79 | if (!localcopy || !*localcopy) { |
| 80 | sfree(localcopy); |
| 81 | localcopy = dupstr(":0"); /* plausible default for any platform */ |
| 82 | } |
| 83 | } else |
| 84 | localcopy = dupstr(display); |
| 85 | |
| 86 | /* |
| 87 | * Parse the display name. |
| 88 | * |
| 89 | * We expect this to have one of the following forms: |
| 90 | * |
| 91 | * - the standard X format which looks like |
| 92 | * [ [ protocol '/' ] host ] ':' displaynumber [ '.' screennumber ] |
| 93 | * (X11 also permits a double colon to indicate DECnet, but |
| 94 | * that's not our problem, thankfully!) |
| 95 | * |
| 96 | * - only seen in the wild on MacOS (so far): a pathname to a |
| 97 | * Unix-domain socket, which will typically and confusingly |
| 98 | * end in ":0", and which I'm currently distinguishing from |
| 99 | * the standard scheme by noting that it starts with '/'. |
| 100 | */ |
| 101 | if (localcopy[0] == '/') { |
| 102 | disp->unixsocketpath = localcopy; |
| 103 | disp->unixdomain = TRUE; |
| 104 | disp->hostname = NULL; |
| 105 | disp->displaynum = -1; |
| 106 | disp->screennum = 0; |
| 107 | disp->addr = NULL; |
| 108 | } else { |
| 109 | char *colon, *dot, *slash; |
| 110 | char *protocol, *hostname; |
| 111 | |
| 112 | colon = strrchr(localcopy, ':'); |
| 113 | if (!colon) { |
| 114 | sfree(disp); |
| 115 | sfree(localcopy); |
| 116 | return NULL; /* FIXME: report a specific error? */ |
| 117 | } |
| 118 | |
| 119 | *colon++ = '\0'; |
| 120 | dot = strchr(colon, '.'); |
| 121 | if (dot) |
| 122 | *dot++ = '\0'; |
| 123 | |
| 124 | disp->displaynum = atoi(colon); |
| 125 | if (dot) |
| 126 | disp->screennum = atoi(dot); |
| 127 | else |
| 128 | disp->screennum = 0; |
| 129 | |
| 130 | protocol = NULL; |
| 131 | hostname = localcopy; |
| 132 | if (colon > localcopy) { |
| 133 | slash = strchr(localcopy, '/'); |
| 134 | if (slash) { |
| 135 | *slash++ = '\0'; |
| 136 | protocol = localcopy; |
| 137 | hostname = slash; |
| 138 | } |
| 139 | } |
| 140 | |
| 141 | disp->hostname = *hostname ? dupstr(hostname) : NULL; |
| 142 | |
| 143 | if (protocol) |
| 144 | disp->unixdomain = (!strcmp(protocol, "local") || |
| 145 | !strcmp(protocol, "unix")); |
| 146 | else if (!*hostname || !strcmp(hostname, "unix")) |
| 147 | disp->unixdomain = platform_uses_x11_unix_by_default; |
| 148 | else |
| 149 | disp->unixdomain = FALSE; |
| 150 | |
| 151 | if (!disp->hostname && !disp->unixdomain) |
| 152 | disp->hostname = dupstr("localhost"); |
| 153 | |
| 154 | disp->unixsocketpath = NULL; |
| 155 | disp->addr = NULL; |
| 156 | |
| 157 | sfree(localcopy); |
| 158 | } |
| 159 | |
| 160 | /* |
| 161 | * Look up the display hostname, if we need to. |
| 162 | */ |
| 163 | if (!disp->unixdomain) { |
| 164 | const char *err; |
| 165 | |
| 166 | disp->port = 6000 + disp->displaynum; |
| 167 | disp->addr = name_lookup(disp->hostname, disp->port, |
| 168 | &disp->realhost, conf, ADDRTYPE_UNSPEC); |
| 169 | |
| 170 | if ((err = sk_addr_error(disp->addr)) != NULL) { |
| 171 | sk_addr_free(disp->addr); |
| 172 | sfree(disp->hostname); |
| 173 | sfree(disp->unixsocketpath); |
| 174 | return NULL; /* FIXME: report an error */ |
| 175 | } |
| 176 | } |
| 177 | |
| 178 | /* |
| 179 | * Try upgrading an IP-style localhost display to a Unix-socket |
| 180 | * display (as the standard X connection libraries do). |
| 181 | */ |
| 182 | if (!disp->unixdomain && sk_address_is_local(disp->addr)) { |
| 183 | SockAddr ux = platform_get_x11_unix_address(NULL, disp->displaynum); |
| 184 | const char *err = sk_addr_error(ux); |
| 185 | if (!err) { |
| 186 | /* Create trial connection to see if there is a useful Unix-domain |
| 187 | * socket */ |
| 188 | const struct plug_function_table *dummy = &dummy_plug; |
| 189 | Socket s = sk_new(sk_addr_dup(ux), 0, 0, 0, 0, 0, (Plug)&dummy); |
| 190 | err = sk_socket_error(s); |
| 191 | sk_close(s); |
| 192 | } |
| 193 | if (err) { |
| 194 | sk_addr_free(ux); |
| 195 | } else { |
| 196 | sk_addr_free(disp->addr); |
| 197 | disp->unixdomain = TRUE; |
| 198 | disp->addr = ux; |
| 199 | /* Fill in the rest in a moment */ |
| 200 | } |
| 201 | } |
| 202 | |
| 203 | if (disp->unixdomain) { |
| 204 | if (!disp->addr) |
| 205 | disp->addr = platform_get_x11_unix_address(disp->unixsocketpath, |
| 206 | disp->displaynum); |
| 207 | if (disp->unixsocketpath) |
| 208 | disp->realhost = dupstr(disp->unixsocketpath); |
| 209 | else |
| 210 | disp->realhost = dupprintf("unix:%d", disp->displaynum); |
| 211 | disp->port = 0; |
| 212 | } |
| 213 | |
| 214 | /* |
| 215 | * Invent the remote authorisation details. |
| 216 | */ |
| 217 | if (authtype == X11_MIT) { |
| 218 | disp->remoteauthproto = X11_MIT; |
| 219 | |
| 220 | /* MIT-MAGIC-COOKIE-1. Cookie size is 128 bits (16 bytes). */ |
| 221 | disp->remoteauthdata = snewn(16, unsigned char); |
| 222 | for (i = 0; i < 16; i++) |
| 223 | disp->remoteauthdata[i] = random_byte(); |
| 224 | disp->remoteauthdatalen = 16; |
| 225 | |
| 226 | disp->xdmseen = NULL; |
| 227 | } else { |
| 228 | assert(authtype == X11_XDM); |
| 229 | disp->remoteauthproto = X11_XDM; |
| 230 | |
| 231 | /* XDM-AUTHORIZATION-1. Cookie size is 16 bytes; byte 8 is zero. */ |
| 232 | disp->remoteauthdata = snewn(16, unsigned char); |
| 233 | for (i = 0; i < 16; i++) |
| 234 | disp->remoteauthdata[i] = (i == 8 ? 0 : random_byte()); |
| 235 | disp->remoteauthdatalen = 16; |
| 236 | |
| 237 | disp->xdmseen = newtree234(xdmseen_cmp); |
| 238 | } |
| 239 | disp->remoteauthprotoname = dupstr(x11_authnames[disp->remoteauthproto]); |
| 240 | disp->remoteauthdatastring = snewn(disp->remoteauthdatalen * 2 + 1, char); |
| 241 | for (i = 0; i < disp->remoteauthdatalen; i++) |
| 242 | sprintf(disp->remoteauthdatastring + i*2, "%02x", |
| 243 | disp->remoteauthdata[i]); |
| 244 | |
| 245 | /* |
| 246 | * Fetch the local authorisation details. |
| 247 | */ |
| 248 | disp->localauthproto = X11_NO_AUTH; |
| 249 | disp->localauthdata = NULL; |
| 250 | disp->localauthdatalen = 0; |
| 251 | platform_get_x11_auth(disp, conf); |
| 252 | |
| 253 | return disp; |
| 254 | } |
| 255 | |
| 256 | void x11_free_display(struct X11Display *disp) |
| 257 | { |
| 258 | if (disp->xdmseen != NULL) { |
| 259 | struct XDMSeen *seen; |
| 260 | while ((seen = delpos234(disp->xdmseen, 0)) != NULL) |
| 261 | sfree(seen); |
| 262 | freetree234(disp->xdmseen); |
| 263 | } |
| 264 | sfree(disp->hostname); |
| 265 | sfree(disp->unixsocketpath); |
| 266 | if (disp->localauthdata) |
| 267 | smemclr(disp->localauthdata, disp->localauthdatalen); |
| 268 | sfree(disp->localauthdata); |
| 269 | if (disp->remoteauthdata) |
| 270 | smemclr(disp->remoteauthdata, disp->remoteauthdatalen); |
| 271 | sfree(disp->remoteauthdata); |
| 272 | sfree(disp->remoteauthprotoname); |
| 273 | sfree(disp->remoteauthdatastring); |
| 274 | sk_addr_free(disp->addr); |
| 275 | sfree(disp); |
| 276 | } |
| 277 | |
| 278 | #define XDM_MAXSKEW 20*60 /* 20 minute clock skew should be OK */ |
| 279 | |
| 280 | static char *x11_verify(unsigned long peer_ip, int peer_port, |
| 281 | struct X11Display *disp, char *proto, |
| 282 | unsigned char *data, int dlen) |
| 283 | { |
| 284 | if (strcmp(proto, x11_authnames[disp->remoteauthproto]) != 0) |
| 285 | return "wrong authorisation protocol attempted"; |
| 286 | if (disp->remoteauthproto == X11_MIT) { |
| 287 | if (dlen != disp->remoteauthdatalen) |
| 288 | return "MIT-MAGIC-COOKIE-1 data was wrong length"; |
| 289 | if (memcmp(disp->remoteauthdata, data, dlen) != 0) |
| 290 | return "MIT-MAGIC-COOKIE-1 data did not match"; |
| 291 | } |
| 292 | if (disp->remoteauthproto == X11_XDM) { |
| 293 | unsigned long t; |
| 294 | time_t tim; |
| 295 | int i; |
| 296 | struct XDMSeen *seen, *ret; |
| 297 | |
| 298 | if (dlen != 24) |
| 299 | return "XDM-AUTHORIZATION-1 data was wrong length"; |
| 300 | if (peer_port == -1) |
| 301 | return "cannot do XDM-AUTHORIZATION-1 without remote address data"; |
| 302 | des_decrypt_xdmauth(disp->remoteauthdata+9, data, 24); |
| 303 | if (memcmp(disp->remoteauthdata, data, 8) != 0) |
| 304 | return "XDM-AUTHORIZATION-1 data failed check"; /* cookie wrong */ |
| 305 | if (GET_32BIT_MSB_FIRST(data+8) != peer_ip) |
| 306 | return "XDM-AUTHORIZATION-1 data failed check"; /* IP wrong */ |
| 307 | if ((int)GET_16BIT_MSB_FIRST(data+12) != peer_port) |
| 308 | return "XDM-AUTHORIZATION-1 data failed check"; /* port wrong */ |
| 309 | t = GET_32BIT_MSB_FIRST(data+14); |
| 310 | for (i = 18; i < 24; i++) |
| 311 | if (data[i] != 0) /* zero padding wrong */ |
| 312 | return "XDM-AUTHORIZATION-1 data failed check"; |
| 313 | tim = time(NULL); |
| 314 | if (abs(t - tim) > XDM_MAXSKEW) |
| 315 | return "XDM-AUTHORIZATION-1 time stamp was too far out"; |
| 316 | seen = snew(struct XDMSeen); |
| 317 | seen->time = t; |
| 318 | memcpy(seen->clientid, data+8, 6); |
| 319 | assert(disp->xdmseen != NULL); |
| 320 | ret = add234(disp->xdmseen, seen); |
| 321 | if (ret != seen) { |
| 322 | sfree(seen); |
| 323 | return "XDM-AUTHORIZATION-1 data replayed"; |
| 324 | } |
| 325 | /* While we're here, purge entries too old to be replayed. */ |
| 326 | for (;;) { |
| 327 | seen = index234(disp->xdmseen, 0); |
| 328 | assert(seen != NULL); |
| 329 | if (t - seen->time <= XDM_MAXSKEW) |
| 330 | break; |
| 331 | sfree(delpos234(disp->xdmseen, 0)); |
| 332 | } |
| 333 | } |
| 334 | /* implement other protocols here if ever required */ |
| 335 | return NULL; |
| 336 | } |
| 337 | |
| 338 | void x11_get_auth_from_authfile(struct X11Display *disp, |
| 339 | const char *authfilename) |
| 340 | { |
| 341 | FILE *authfp; |
| 342 | char *buf, *ptr, *str[4]; |
| 343 | int len[4]; |
| 344 | int family, protocol; |
| 345 | int ideal_match = FALSE; |
| 346 | char *ourhostname = get_hostname(); |
| 347 | |
| 348 | /* |
| 349 | * Normally we should look for precisely the details specified in |
| 350 | * `disp'. However, there's an oddity when the display is local: |
| 351 | * displays like "localhost:0" usually have their details stored |
| 352 | * in a Unix-domain-socket record (even if there isn't actually a |
| 353 | * real Unix-domain socket available, as with OpenSSH's proxy X11 |
| 354 | * server). |
| 355 | * |
| 356 | * This is apparently a fudge to get round the meaninglessness of |
| 357 | * "localhost" in a shared-home-directory context -- xauth entries |
| 358 | * for Unix-domain sockets already disambiguate this by storing |
| 359 | * the *local* hostname in the conveniently-blank hostname field, |
| 360 | * but IP "localhost" records couldn't do this. So, typically, an |
| 361 | * IP "localhost" entry in the auth database isn't present and if |
| 362 | * it were it would be ignored. |
| 363 | * |
| 364 | * However, we don't entirely trust that (say) Windows X servers |
| 365 | * won't rely on a straight "localhost" entry, bad idea though |
| 366 | * that is; so if we can't find a Unix-domain-socket entry we'll |
| 367 | * fall back to an IP-based entry if we can find one. |
| 368 | */ |
| 369 | int localhost = !disp->unixdomain && sk_address_is_local(disp->addr); |
| 370 | |
| 371 | authfp = fopen(authfilename, "rb"); |
| 372 | if (!authfp) |
| 373 | return; |
| 374 | |
| 375 | /* Records in .Xauthority contain four strings of up to 64K each */ |
| 376 | buf = snewn(65537 * 4, char); |
| 377 | |
| 378 | while (!ideal_match) { |
| 379 | int c, i, j, match = FALSE; |
| 380 | |
| 381 | #define GET do { c = fgetc(authfp); if (c == EOF) goto done; c = (unsigned char)c; } while (0) |
| 382 | /* Expect a big-endian 2-byte number giving address family */ |
| 383 | GET; family = c; |
| 384 | GET; family = (family << 8) | c; |
| 385 | /* Then expect four strings, each composed of a big-endian 2-byte |
| 386 | * length field followed by that many bytes of data */ |
| 387 | ptr = buf; |
| 388 | for (i = 0; i < 4; i++) { |
| 389 | GET; len[i] = c; |
| 390 | GET; len[i] = (len[i] << 8) | c; |
| 391 | str[i] = ptr; |
| 392 | for (j = 0; j < len[i]; j++) { |
| 393 | GET; *ptr++ = c; |
| 394 | } |
| 395 | *ptr++ = '\0'; |
| 396 | } |
| 397 | #undef GET |
| 398 | |
| 399 | /* |
| 400 | * Now we have a full X authority record in memory. See |
| 401 | * whether it matches the display we're trying to |
| 402 | * authenticate to. |
| 403 | * |
| 404 | * The details we've just read should be interpreted as |
| 405 | * follows: |
| 406 | * |
| 407 | * - 'family' is the network address family used to |
| 408 | * connect to the display. 0 means IPv4; 6 means IPv6; |
| 409 | * 256 means Unix-domain sockets. |
| 410 | * |
| 411 | * - str[0] is the network address itself. For IPv4 and |
| 412 | * IPv6, this is a string of binary data of the |
| 413 | * appropriate length (respectively 4 and 16 bytes) |
| 414 | * representing the address in big-endian format, e.g. |
| 415 | * 7F 00 00 01 means IPv4 localhost. For Unix-domain |
| 416 | * sockets, this is the host name of the machine on |
| 417 | * which the Unix-domain display resides (so that an |
| 418 | * .Xauthority file on a shared file system can contain |
| 419 | * authority entries for Unix-domain displays on |
| 420 | * several machines without them clashing). |
| 421 | * |
| 422 | * - str[1] is the display number. I've no idea why |
| 423 | * .Xauthority stores this as a string when it has a |
| 424 | * perfectly good integer format, but there we go. |
| 425 | * |
| 426 | * - str[2] is the authorisation method, encoded as its |
| 427 | * canonical string name (i.e. "MIT-MAGIC-COOKIE-1", |
| 428 | * "XDM-AUTHORIZATION-1" or something we don't |
| 429 | * recognise). |
| 430 | * |
| 431 | * - str[3] is the actual authorisation data, stored in |
| 432 | * binary form. |
| 433 | */ |
| 434 | |
| 435 | if (disp->displaynum < 0 || disp->displaynum != atoi(str[1])) |
| 436 | continue; /* not the one */ |
| 437 | |
| 438 | for (protocol = 1; protocol < lenof(x11_authnames); protocol++) |
| 439 | if (!strcmp(str[2], x11_authnames[protocol])) |
| 440 | break; |
| 441 | if (protocol == lenof(x11_authnames)) |
| 442 | continue; /* don't recognise this protocol, look for another */ |
| 443 | |
| 444 | switch (family) { |
| 445 | case 0: /* IPv4 */ |
| 446 | if (!disp->unixdomain && |
| 447 | sk_addrtype(disp->addr) == ADDRTYPE_IPV4) { |
| 448 | char buf[4]; |
| 449 | sk_addrcopy(disp->addr, buf); |
| 450 | if (len[0] == 4 && !memcmp(str[0], buf, 4)) { |
| 451 | match = TRUE; |
| 452 | /* If this is a "localhost" entry, note it down |
| 453 | * but carry on looking for a Unix-domain entry. */ |
| 454 | ideal_match = !localhost; |
| 455 | } |
| 456 | } |
| 457 | break; |
| 458 | case 6: /* IPv6 */ |
| 459 | if (!disp->unixdomain && |
| 460 | sk_addrtype(disp->addr) == ADDRTYPE_IPV6) { |
| 461 | char buf[16]; |
| 462 | sk_addrcopy(disp->addr, buf); |
| 463 | if (len[0] == 16 && !memcmp(str[0], buf, 16)) { |
| 464 | match = TRUE; |
| 465 | ideal_match = !localhost; |
| 466 | } |
| 467 | } |
| 468 | break; |
| 469 | case 256: /* Unix-domain / localhost */ |
| 470 | if ((disp->unixdomain || localhost) |
| 471 | && ourhostname && !strcmp(ourhostname, str[0])) |
| 472 | /* A matching Unix-domain socket is always the best |
| 473 | * match. */ |
| 474 | match = ideal_match = TRUE; |
| 475 | break; |
| 476 | } |
| 477 | |
| 478 | if (match) { |
| 479 | /* Current best guess -- may be overridden if !ideal_match */ |
| 480 | disp->localauthproto = protocol; |
| 481 | sfree(disp->localauthdata); /* free previous guess, if any */ |
| 482 | disp->localauthdata = snewn(len[3], unsigned char); |
| 483 | memcpy(disp->localauthdata, str[3], len[3]); |
| 484 | disp->localauthdatalen = len[3]; |
| 485 | } |
| 486 | } |
| 487 | |
| 488 | done: |
| 489 | fclose(authfp); |
| 490 | smemclr(buf, 65537 * 4); |
| 491 | sfree(buf); |
| 492 | sfree(ourhostname); |
| 493 | } |
| 494 | |
| 495 | static void x11_log(Plug p, int type, SockAddr addr, int port, |
| 496 | const char *error_msg, int error_code) |
| 497 | { |
| 498 | /* We have no interface to the logging module here, so we drop these. */ |
| 499 | } |
| 500 | |
| 501 | static int x11_closing(Plug plug, const char *error_msg, int error_code, |
| 502 | int calling_back) |
| 503 | { |
| 504 | struct X11Private *pr = (struct X11Private *) plug; |
| 505 | |
| 506 | if (error_msg) { |
| 507 | /* |
| 508 | * Socket error. Slam the connection instantly shut. |
| 509 | */ |
| 510 | sshfwd_unclean_close(pr->c); |
| 511 | } else { |
| 512 | /* |
| 513 | * Ordinary EOF received on socket. Send an EOF on the SSH |
| 514 | * channel. |
| 515 | */ |
| 516 | if (pr->c) |
| 517 | sshfwd_write_eof(pr->c); |
| 518 | } |
| 519 | |
| 520 | return 1; |
| 521 | } |
| 522 | |
| 523 | static int x11_receive(Plug plug, int urgent, char *data, int len) |
| 524 | { |
| 525 | struct X11Private *pr = (struct X11Private *) plug; |
| 526 | |
| 527 | if (sshfwd_write(pr->c, data, len) > 0) { |
| 528 | pr->throttled = 1; |
| 529 | sk_set_frozen(pr->s, 1); |
| 530 | } |
| 531 | |
| 532 | return 1; |
| 533 | } |
| 534 | |
| 535 | static void x11_sent(Plug plug, int bufsize) |
| 536 | { |
| 537 | struct X11Private *pr = (struct X11Private *) plug; |
| 538 | |
| 539 | sshfwd_unthrottle(pr->c, bufsize); |
| 540 | } |
| 541 | |
| 542 | /* |
| 543 | * When setting up X forwarding, we should send the screen number |
| 544 | * from the specified local display. This function extracts it from |
| 545 | * the display string. |
| 546 | */ |
| 547 | int x11_get_screen_number(char *display) |
| 548 | { |
| 549 | int n; |
| 550 | |
| 551 | n = strcspn(display, ":"); |
| 552 | if (!display[n]) |
| 553 | return 0; |
| 554 | n = strcspn(display, "."); |
| 555 | if (!display[n]) |
| 556 | return 0; |
| 557 | return atoi(display + n + 1); |
| 558 | } |
| 559 | |
| 560 | /* |
| 561 | * Called to set up the raw connection. |
| 562 | * |
| 563 | * Returns an error message, or NULL on success. |
| 564 | * also, fills the SocketsStructure |
| 565 | */ |
| 566 | extern const char *x11_init(Socket *s, struct X11Display *disp, void *c, |
| 567 | const char *peeraddr, int peerport, Conf *conf) |
| 568 | { |
| 569 | static const struct plug_function_table fn_table = { |
| 570 | x11_log, |
| 571 | x11_closing, |
| 572 | x11_receive, |
| 573 | x11_sent, |
| 574 | NULL |
| 575 | }; |
| 576 | |
| 577 | const char *err; |
| 578 | struct X11Private *pr; |
| 579 | |
| 580 | /* |
| 581 | * Open socket. |
| 582 | */ |
| 583 | pr = snew(struct X11Private); |
| 584 | pr->fn = &fn_table; |
| 585 | pr->auth_protocol = NULL; |
| 586 | pr->disp = disp; |
| 587 | pr->verified = 0; |
| 588 | pr->data_read = 0; |
| 589 | pr->throttled = pr->throttle_override = 0; |
| 590 | pr->c = c; |
| 591 | |
| 592 | pr->s = *s = new_connection(sk_addr_dup(disp->addr), |
| 593 | disp->realhost, disp->port, |
| 594 | 0, 1, 0, 0, (Plug) pr, conf); |
| 595 | if ((err = sk_socket_error(*s)) != NULL) { |
| 596 | sfree(pr); |
| 597 | return err; |
| 598 | } |
| 599 | |
| 600 | /* |
| 601 | * See if we can make sense of the peer address we were given. |
| 602 | */ |
| 603 | { |
| 604 | int i[4]; |
| 605 | if (peeraddr && |
| 606 | 4 == sscanf(peeraddr, "%d.%d.%d.%d", i+0, i+1, i+2, i+3)) { |
| 607 | pr->peer_ip = (i[0] << 24) | (i[1] << 16) | (i[2] << 8) | i[3]; |
| 608 | pr->peer_port = peerport; |
| 609 | } else { |
| 610 | pr->peer_ip = 0; |
| 611 | pr->peer_port = -1; |
| 612 | } |
| 613 | } |
| 614 | |
| 615 | sk_set_private_ptr(*s, pr); |
| 616 | return NULL; |
| 617 | } |
| 618 | |
| 619 | void x11_close(Socket s) |
| 620 | { |
| 621 | struct X11Private *pr; |
| 622 | if (!s) |
| 623 | return; |
| 624 | pr = (struct X11Private *) sk_get_private_ptr(s); |
| 625 | if (pr->auth_protocol) { |
| 626 | sfree(pr->auth_protocol); |
| 627 | sfree(pr->auth_data); |
| 628 | } |
| 629 | |
| 630 | sfree(pr); |
| 631 | |
| 632 | sk_close(s); |
| 633 | } |
| 634 | |
| 635 | void x11_unthrottle(Socket s) |
| 636 | { |
| 637 | struct X11Private *pr; |
| 638 | if (!s) |
| 639 | return; |
| 640 | pr = (struct X11Private *) sk_get_private_ptr(s); |
| 641 | |
| 642 | pr->throttled = 0; |
| 643 | sk_set_frozen(s, pr->throttled || pr->throttle_override); |
| 644 | } |
| 645 | |
| 646 | void x11_override_throttle(Socket s, int enable) |
| 647 | { |
| 648 | struct X11Private *pr; |
| 649 | if (!s) |
| 650 | return; |
| 651 | pr = (struct X11Private *) sk_get_private_ptr(s); |
| 652 | |
| 653 | pr->throttle_override = enable; |
| 654 | sk_set_frozen(s, pr->throttled || pr->throttle_override); |
| 655 | } |
| 656 | |
| 657 | /* |
| 658 | * Called to send data down the raw connection. |
| 659 | */ |
| 660 | int x11_send(Socket s, char *data, int len) |
| 661 | { |
| 662 | struct X11Private *pr; |
| 663 | if (!s) |
| 664 | return 0; |
| 665 | pr = (struct X11Private *) sk_get_private_ptr(s); |
| 666 | |
| 667 | /* |
| 668 | * Read the first packet. |
| 669 | */ |
| 670 | while (len > 0 && pr->data_read < 12) |
| 671 | pr->firstpkt[pr->data_read++] = (unsigned char) (len--, *data++); |
| 672 | if (pr->data_read < 12) |
| 673 | return 0; |
| 674 | |
| 675 | /* |
| 676 | * If we have not allocated the auth_protocol and auth_data |
| 677 | * strings, do so now. |
| 678 | */ |
| 679 | if (!pr->auth_protocol) { |
| 680 | pr->auth_plen = GET_16BIT(pr->firstpkt[0], pr->firstpkt + 6); |
| 681 | pr->auth_dlen = GET_16BIT(pr->firstpkt[0], pr->firstpkt + 8); |
| 682 | pr->auth_psize = (pr->auth_plen + 3) & ~3; |
| 683 | pr->auth_dsize = (pr->auth_dlen + 3) & ~3; |
| 684 | /* Leave room for a terminating zero, to make our lives easier. */ |
| 685 | pr->auth_protocol = snewn(pr->auth_psize + 1, char); |
| 686 | pr->auth_data = snewn(pr->auth_dsize, unsigned char); |
| 687 | } |
| 688 | |
| 689 | /* |
| 690 | * Read the auth_protocol and auth_data strings. |
| 691 | */ |
| 692 | while (len > 0 && pr->data_read < 12 + pr->auth_psize) |
| 693 | pr->auth_protocol[pr->data_read++ - 12] = (len--, *data++); |
| 694 | while (len > 0 && pr->data_read < 12 + pr->auth_psize + pr->auth_dsize) |
| 695 | pr->auth_data[pr->data_read++ - 12 - |
| 696 | pr->auth_psize] = (unsigned char) (len--, *data++); |
| 697 | if (pr->data_read < 12 + pr->auth_psize + pr->auth_dsize) |
| 698 | return 0; |
| 699 | |
| 700 | /* |
| 701 | * If we haven't verified the authorisation, do so now. |
| 702 | */ |
| 703 | if (!pr->verified) { |
| 704 | char *err; |
| 705 | |
| 706 | pr->auth_protocol[pr->auth_plen] = '\0'; /* ASCIZ */ |
| 707 | err = x11_verify(pr->peer_ip, pr->peer_port, |
| 708 | pr->disp, pr->auth_protocol, |
| 709 | pr->auth_data, pr->auth_dlen); |
| 710 | |
| 711 | /* |
| 712 | * If authorisation failed, construct and send an error |
| 713 | * packet, then terminate the connection. |
| 714 | */ |
| 715 | if (err) { |
| 716 | char *message; |
| 717 | int msglen, msgsize; |
| 718 | unsigned char *reply; |
| 719 | |
| 720 | message = dupprintf("%s X11 proxy: %s", appname, err); |
| 721 | msglen = strlen(message); |
| 722 | reply = snewn(8 + msglen+1 + 4, unsigned char); /* include zero */ |
| 723 | msgsize = (msglen + 3) & ~3; |
| 724 | reply[0] = 0; /* failure */ |
| 725 | reply[1] = msglen; /* length of reason string */ |
| 726 | memcpy(reply + 2, pr->firstpkt + 2, 4); /* major/minor proto vsn */ |
| 727 | PUT_16BIT(pr->firstpkt[0], reply + 6, msgsize >> 2);/* data len */ |
| 728 | memset(reply + 8, 0, msgsize); |
| 729 | memcpy(reply + 8, message, msglen); |
| 730 | sshfwd_write(pr->c, (char *)reply, 8 + msgsize); |
| 731 | sshfwd_write_eof(pr->c); |
| 732 | sfree(reply); |
| 733 | sfree(message); |
| 734 | return 0; |
| 735 | } |
| 736 | |
| 737 | /* |
| 738 | * Now we know we're going to accept the connection. Strip |
| 739 | * the fake auth data, and optionally put real auth data in |
| 740 | * instead. |
| 741 | */ |
| 742 | { |
| 743 | char realauthdata[64]; |
| 744 | int realauthlen = 0; |
| 745 | int authstrlen = strlen(x11_authnames[pr->disp->localauthproto]); |
| 746 | int buflen = 0; /* initialise to placate optimiser */ |
| 747 | static const char zeroes[4] = { 0,0,0,0 }; |
| 748 | void *buf; |
| 749 | |
| 750 | if (pr->disp->localauthproto == X11_MIT) { |
| 751 | assert(pr->disp->localauthdatalen <= lenof(realauthdata)); |
| 752 | realauthlen = pr->disp->localauthdatalen; |
| 753 | memcpy(realauthdata, pr->disp->localauthdata, realauthlen); |
| 754 | } else if (pr->disp->localauthproto == X11_XDM && |
| 755 | pr->disp->localauthdatalen == 16 && |
| 756 | ((buf = sk_getxdmdata(s, &buflen))!=0)) { |
| 757 | time_t t; |
| 758 | realauthlen = (buflen+12+7) & ~7; |
| 759 | assert(realauthlen <= lenof(realauthdata)); |
| 760 | memset(realauthdata, 0, realauthlen); |
| 761 | memcpy(realauthdata, pr->disp->localauthdata, 8); |
| 762 | memcpy(realauthdata+8, buf, buflen); |
| 763 | t = time(NULL); |
| 764 | PUT_32BIT_MSB_FIRST(realauthdata+8+buflen, t); |
| 765 | des_encrypt_xdmauth(pr->disp->localauthdata+9, |
| 766 | (unsigned char *)realauthdata, |
| 767 | realauthlen); |
| 768 | sfree(buf); |
| 769 | } |
| 770 | /* implement other auth methods here if required */ |
| 771 | |
| 772 | PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 6, authstrlen); |
| 773 | PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 8, realauthlen); |
| 774 | |
| 775 | sk_write(s, (char *)pr->firstpkt, 12); |
| 776 | |
| 777 | if (authstrlen) { |
| 778 | sk_write(s, x11_authnames[pr->disp->localauthproto], |
| 779 | authstrlen); |
| 780 | sk_write(s, zeroes, 3 & (-authstrlen)); |
| 781 | } |
| 782 | if (realauthlen) { |
| 783 | sk_write(s, realauthdata, realauthlen); |
| 784 | sk_write(s, zeroes, 3 & (-realauthlen)); |
| 785 | } |
| 786 | } |
| 787 | pr->verified = 1; |
| 788 | } |
| 789 | |
| 790 | /* |
| 791 | * After initialisation, just copy data simply. |
| 792 | */ |
| 793 | |
| 794 | return sk_write(s, data, len); |
| 795 | } |
| 796 | |
| 797 | void x11_send_eof(Socket s) |
| 798 | { |
| 799 | sk_write_eof(s); |
| 800 | } |