ssi: Convert legacy SSI_SLAVE -> DEVICE casts
[qemu.git] / ui / vnc-auth-sasl.c
blobf3ad75d52bb5e12bef8e9472027fb96eee652c8d
1 /*
2 * QEMU VNC display driver: SASL auth protocol
4 * Copyright (C) 2009 Red Hat, Inc
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
25 #include "vnc.h"
27 /* Max amount of data we send/recv for SASL steps to prevent DOS */
28 #define SASL_DATA_MAX_LEN (1024 * 1024)
31 void vnc_sasl_client_cleanup(VncState *vs)
33 if (vs->sasl.conn) {
34 vs->sasl.runSSF = false;
35 vs->sasl.wantSSF = false;
36 vs->sasl.waitWriteSSF = 0;
37 vs->sasl.encodedLength = vs->sasl.encodedOffset = 0;
38 vs->sasl.encoded = NULL;
39 g_free(vs->sasl.username);
40 g_free(vs->sasl.mechlist);
41 vs->sasl.username = vs->sasl.mechlist = NULL;
42 sasl_dispose(&vs->sasl.conn);
43 vs->sasl.conn = NULL;
48 long vnc_client_write_sasl(VncState *vs)
50 long ret;
52 VNC_DEBUG("Write SASL: Pending output %p size %zd offset %zd "
53 "Encoded: %p size %d offset %d\n",
54 vs->output.buffer, vs->output.capacity, vs->output.offset,
55 vs->sasl.encoded, vs->sasl.encodedLength, vs->sasl.encodedOffset);
57 if (!vs->sasl.encoded) {
58 int err;
59 err = sasl_encode(vs->sasl.conn,
60 (char *)vs->output.buffer,
61 vs->output.offset,
62 (const char **)&vs->sasl.encoded,
63 &vs->sasl.encodedLength);
64 if (err != SASL_OK)
65 return vnc_client_io_error(vs, -1, EIO);
67 vs->sasl.encodedOffset = 0;
70 ret = vnc_client_write_buf(vs,
71 vs->sasl.encoded + vs->sasl.encodedOffset,
72 vs->sasl.encodedLength - vs->sasl.encodedOffset);
73 if (!ret)
74 return 0;
76 vs->sasl.encodedOffset += ret;
77 if (vs->sasl.encodedOffset == vs->sasl.encodedLength) {
78 vs->output.offset = 0;
79 vs->sasl.encoded = NULL;
80 vs->sasl.encodedOffset = vs->sasl.encodedLength = 0;
83 /* Can't merge this block with one above, because
84 * someone might have written more unencrypted
85 * data in vs->output while we were processing
86 * SASL encoded output
88 if (vs->output.offset == 0) {
89 qemu_set_fd_handler2(vs->csock, NULL, vnc_client_read, NULL, vs);
92 return ret;
96 long vnc_client_read_sasl(VncState *vs)
98 long ret;
99 uint8_t encoded[4096];
100 const char *decoded;
101 unsigned int decodedLen;
102 int err;
104 ret = vnc_client_read_buf(vs, encoded, sizeof(encoded));
105 if (!ret)
106 return 0;
108 err = sasl_decode(vs->sasl.conn,
109 (char *)encoded, ret,
110 &decoded, &decodedLen);
112 if (err != SASL_OK)
113 return vnc_client_io_error(vs, -1, -EIO);
114 VNC_DEBUG("Read SASL Encoded %p size %ld Decoded %p size %d\n",
115 encoded, ret, decoded, decodedLen);
116 buffer_reserve(&vs->input, decodedLen);
117 buffer_append(&vs->input, decoded, decodedLen);
118 return decodedLen;
122 static int vnc_auth_sasl_check_access(VncState *vs)
124 const void *val;
125 int err;
126 int allow;
128 err = sasl_getprop(vs->sasl.conn, SASL_USERNAME, &val);
129 if (err != SASL_OK) {
130 VNC_DEBUG("cannot query SASL username on connection %d (%s), denying access\n",
131 err, sasl_errstring(err, NULL, NULL));
132 return -1;
134 if (val == NULL) {
135 VNC_DEBUG("no client username was found, denying access\n");
136 return -1;
138 VNC_DEBUG("SASL client username %s\n", (const char *)val);
140 vs->sasl.username = g_strdup((const char*)val);
142 if (vs->vd->sasl.acl == NULL) {
143 VNC_DEBUG("no ACL activated, allowing access\n");
144 return 0;
147 allow = qemu_acl_party_is_allowed(vs->vd->sasl.acl, vs->sasl.username);
149 VNC_DEBUG("SASL client %s %s by ACL\n", vs->sasl.username,
150 allow ? "allowed" : "denied");
151 return allow ? 0 : -1;
154 static int vnc_auth_sasl_check_ssf(VncState *vs)
156 const void *val;
157 int err, ssf;
159 if (!vs->sasl.wantSSF)
160 return 1;
162 err = sasl_getprop(vs->sasl.conn, SASL_SSF, &val);
163 if (err != SASL_OK)
164 return 0;
166 ssf = *(const int *)val;
167 VNC_DEBUG("negotiated an SSF of %d\n", ssf);
168 if (ssf < 56)
169 return 0; /* 56 is good for Kerberos */
171 /* Only setup for read initially, because we're about to send an RPC
172 * reply which must be in plain text. When the next incoming RPC
173 * arrives, we'll switch on writes too
175 * cf qemudClientReadSASL in qemud.c
177 vs->sasl.runSSF = 1;
179 /* We have a SSF that's good enough */
180 return 1;
184 * Step Msg
186 * Input from client:
188 * u32 clientin-length
189 * u8-array clientin-string
191 * Output to client:
193 * u32 serverout-length
194 * u8-array serverout-strin
195 * u8 continue
198 static int protocol_client_auth_sasl_step_len(VncState *vs, uint8_t *data, size_t len);
200 static int protocol_client_auth_sasl_step(VncState *vs, uint8_t *data, size_t len)
202 uint32_t datalen = len;
203 const char *serverout;
204 unsigned int serveroutlen;
205 int err;
206 char *clientdata = NULL;
208 /* NB, distinction of NULL vs "" is *critical* in SASL */
209 if (datalen) {
210 clientdata = (char*)data;
211 clientdata[datalen-1] = '\0'; /* Wire includes '\0', but make sure */
212 datalen--; /* Don't count NULL byte when passing to _start() */
215 VNC_DEBUG("Step using SASL Data %p (%d bytes)\n",
216 clientdata, datalen);
217 err = sasl_server_step(vs->sasl.conn,
218 clientdata,
219 datalen,
220 &serverout,
221 &serveroutlen);
222 if (err != SASL_OK &&
223 err != SASL_CONTINUE) {
224 VNC_DEBUG("sasl step failed %d (%s)\n",
225 err, sasl_errdetail(vs->sasl.conn));
226 sasl_dispose(&vs->sasl.conn);
227 vs->sasl.conn = NULL;
228 goto authabort;
231 if (serveroutlen > SASL_DATA_MAX_LEN) {
232 VNC_DEBUG("sasl step reply data too long %d\n",
233 serveroutlen);
234 sasl_dispose(&vs->sasl.conn);
235 vs->sasl.conn = NULL;
236 goto authabort;
239 VNC_DEBUG("SASL return data %d bytes, nil; %d\n",
240 serveroutlen, serverout ? 0 : 1);
242 if (serveroutlen) {
243 vnc_write_u32(vs, serveroutlen + 1);
244 vnc_write(vs, serverout, serveroutlen + 1);
245 } else {
246 vnc_write_u32(vs, 0);
249 /* Whether auth is complete */
250 vnc_write_u8(vs, err == SASL_CONTINUE ? 0 : 1);
252 if (err == SASL_CONTINUE) {
253 VNC_DEBUG("%s", "Authentication must continue\n");
254 /* Wait for step length */
255 vnc_read_when(vs, protocol_client_auth_sasl_step_len, 4);
256 } else {
257 if (!vnc_auth_sasl_check_ssf(vs)) {
258 VNC_DEBUG("Authentication rejected for weak SSF %d\n", vs->csock);
259 goto authreject;
262 /* Check username whitelist ACL */
263 if (vnc_auth_sasl_check_access(vs) < 0) {
264 VNC_DEBUG("Authentication rejected for ACL %d\n", vs->csock);
265 goto authreject;
268 VNC_DEBUG("Authentication successful %d\n", vs->csock);
269 vnc_write_u32(vs, 0); /* Accept auth */
271 * Delay writing in SSF encoded mode until pending output
272 * buffer is written
274 if (vs->sasl.runSSF)
275 vs->sasl.waitWriteSSF = vs->output.offset;
276 start_client_init(vs);
279 return 0;
281 authreject:
282 vnc_write_u32(vs, 1); /* Reject auth */
283 vnc_write_u32(vs, sizeof("Authentication failed"));
284 vnc_write(vs, "Authentication failed", sizeof("Authentication failed"));
285 vnc_flush(vs);
286 vnc_client_error(vs);
287 return -1;
289 authabort:
290 vnc_client_error(vs);
291 return -1;
294 static int protocol_client_auth_sasl_step_len(VncState *vs, uint8_t *data, size_t len)
296 uint32_t steplen = read_u32(data, 0);
297 VNC_DEBUG("Got client step len %d\n", steplen);
298 if (steplen > SASL_DATA_MAX_LEN) {
299 VNC_DEBUG("Too much SASL data %d\n", steplen);
300 vnc_client_error(vs);
301 return -1;
304 if (steplen == 0)
305 return protocol_client_auth_sasl_step(vs, NULL, 0);
306 else
307 vnc_read_when(vs, protocol_client_auth_sasl_step, steplen);
308 return 0;
312 * Start Msg
314 * Input from client:
316 * u32 clientin-length
317 * u8-array clientin-string
319 * Output to client:
321 * u32 serverout-length
322 * u8-array serverout-strin
323 * u8 continue
326 #define SASL_DATA_MAX_LEN (1024 * 1024)
328 static int protocol_client_auth_sasl_start(VncState *vs, uint8_t *data, size_t len)
330 uint32_t datalen = len;
331 const char *serverout;
332 unsigned int serveroutlen;
333 int err;
334 char *clientdata = NULL;
336 /* NB, distinction of NULL vs "" is *critical* in SASL */
337 if (datalen) {
338 clientdata = (char*)data;
339 clientdata[datalen-1] = '\0'; /* Should be on wire, but make sure */
340 datalen--; /* Don't count NULL byte when passing to _start() */
343 VNC_DEBUG("Start SASL auth with mechanism %s. Data %p (%d bytes)\n",
344 vs->sasl.mechlist, clientdata, datalen);
345 err = sasl_server_start(vs->sasl.conn,
346 vs->sasl.mechlist,
347 clientdata,
348 datalen,
349 &serverout,
350 &serveroutlen);
351 if (err != SASL_OK &&
352 err != SASL_CONTINUE) {
353 VNC_DEBUG("sasl start failed %d (%s)\n",
354 err, sasl_errdetail(vs->sasl.conn));
355 sasl_dispose(&vs->sasl.conn);
356 vs->sasl.conn = NULL;
357 goto authabort;
359 if (serveroutlen > SASL_DATA_MAX_LEN) {
360 VNC_DEBUG("sasl start reply data too long %d\n",
361 serveroutlen);
362 sasl_dispose(&vs->sasl.conn);
363 vs->sasl.conn = NULL;
364 goto authabort;
367 VNC_DEBUG("SASL return data %d bytes, nil; %d\n",
368 serveroutlen, serverout ? 0 : 1);
370 if (serveroutlen) {
371 vnc_write_u32(vs, serveroutlen + 1);
372 vnc_write(vs, serverout, serveroutlen + 1);
373 } else {
374 vnc_write_u32(vs, 0);
377 /* Whether auth is complete */
378 vnc_write_u8(vs, err == SASL_CONTINUE ? 0 : 1);
380 if (err == SASL_CONTINUE) {
381 VNC_DEBUG("%s", "Authentication must continue\n");
382 /* Wait for step length */
383 vnc_read_when(vs, protocol_client_auth_sasl_step_len, 4);
384 } else {
385 if (!vnc_auth_sasl_check_ssf(vs)) {
386 VNC_DEBUG("Authentication rejected for weak SSF %d\n", vs->csock);
387 goto authreject;
390 /* Check username whitelist ACL */
391 if (vnc_auth_sasl_check_access(vs) < 0) {
392 VNC_DEBUG("Authentication rejected for ACL %d\n", vs->csock);
393 goto authreject;
396 VNC_DEBUG("Authentication successful %d\n", vs->csock);
397 vnc_write_u32(vs, 0); /* Accept auth */
398 start_client_init(vs);
401 return 0;
403 authreject:
404 vnc_write_u32(vs, 1); /* Reject auth */
405 vnc_write_u32(vs, sizeof("Authentication failed"));
406 vnc_write(vs, "Authentication failed", sizeof("Authentication failed"));
407 vnc_flush(vs);
408 vnc_client_error(vs);
409 return -1;
411 authabort:
412 vnc_client_error(vs);
413 return -1;
416 static int protocol_client_auth_sasl_start_len(VncState *vs, uint8_t *data, size_t len)
418 uint32_t startlen = read_u32(data, 0);
419 VNC_DEBUG("Got client start len %d\n", startlen);
420 if (startlen > SASL_DATA_MAX_LEN) {
421 VNC_DEBUG("Too much SASL data %d\n", startlen);
422 vnc_client_error(vs);
423 return -1;
426 if (startlen == 0)
427 return protocol_client_auth_sasl_start(vs, NULL, 0);
429 vnc_read_when(vs, protocol_client_auth_sasl_start, startlen);
430 return 0;
433 static int protocol_client_auth_sasl_mechname(VncState *vs, uint8_t *data, size_t len)
435 char *mechname = g_strndup((const char *) data, len);
436 VNC_DEBUG("Got client mechname '%s' check against '%s'\n",
437 mechname, vs->sasl.mechlist);
439 if (strncmp(vs->sasl.mechlist, mechname, len) == 0) {
440 if (vs->sasl.mechlist[len] != '\0' &&
441 vs->sasl.mechlist[len] != ',') {
442 VNC_DEBUG("One %d", vs->sasl.mechlist[len]);
443 goto fail;
445 } else {
446 char *offset = strstr(vs->sasl.mechlist, mechname);
447 VNC_DEBUG("Two %p\n", offset);
448 if (!offset) {
449 goto fail;
451 VNC_DEBUG("Two '%s'\n", offset);
452 if (offset[-1] != ',' ||
453 (offset[len] != '\0'&&
454 offset[len] != ',')) {
455 goto fail;
459 g_free(vs->sasl.mechlist);
460 vs->sasl.mechlist = mechname;
462 VNC_DEBUG("Validated mechname '%s'\n", mechname);
463 vnc_read_when(vs, protocol_client_auth_sasl_start_len, 4);
464 return 0;
466 fail:
467 vnc_client_error(vs);
468 g_free(mechname);
469 return -1;
472 static int protocol_client_auth_sasl_mechname_len(VncState *vs, uint8_t *data, size_t len)
474 uint32_t mechlen = read_u32(data, 0);
475 VNC_DEBUG("Got client mechname len %d\n", mechlen);
476 if (mechlen > 100) {
477 VNC_DEBUG("Too long SASL mechname data %d\n", mechlen);
478 vnc_client_error(vs);
479 return -1;
481 if (mechlen < 1) {
482 VNC_DEBUG("Too short SASL mechname %d\n", mechlen);
483 vnc_client_error(vs);
484 return -1;
486 vnc_read_when(vs, protocol_client_auth_sasl_mechname,mechlen);
487 return 0;
490 void start_auth_sasl(VncState *vs)
492 const char *mechlist = NULL;
493 sasl_security_properties_t secprops;
494 int err;
495 char *localAddr, *remoteAddr;
496 int mechlistlen;
498 VNC_DEBUG("Initialize SASL auth %d\n", vs->csock);
500 /* Get local & remote client addresses in form IPADDR;PORT */
501 if (!(localAddr = vnc_socket_local_addr("%s;%s", vs->csock)))
502 goto authabort;
504 if (!(remoteAddr = vnc_socket_remote_addr("%s;%s", vs->csock))) {
505 g_free(localAddr);
506 goto authabort;
509 err = sasl_server_new("vnc",
510 NULL, /* FQDN - just delegates to gethostname */
511 NULL, /* User realm */
512 localAddr,
513 remoteAddr,
514 NULL, /* Callbacks, not needed */
515 SASL_SUCCESS_DATA,
516 &vs->sasl.conn);
517 g_free(localAddr);
518 g_free(remoteAddr);
519 localAddr = remoteAddr = NULL;
521 if (err != SASL_OK) {
522 VNC_DEBUG("sasl context setup failed %d (%s)",
523 err, sasl_errstring(err, NULL, NULL));
524 vs->sasl.conn = NULL;
525 goto authabort;
528 #ifdef CONFIG_VNC_TLS
529 /* Inform SASL that we've got an external SSF layer from TLS/x509 */
530 if (vs->auth == VNC_AUTH_VENCRYPT &&
531 vs->subauth == VNC_AUTH_VENCRYPT_X509SASL) {
532 gnutls_cipher_algorithm_t cipher;
533 sasl_ssf_t ssf;
535 cipher = gnutls_cipher_get(vs->tls.session);
536 if (!(ssf = (sasl_ssf_t)gnutls_cipher_get_key_size(cipher))) {
537 VNC_DEBUG("%s", "cannot TLS get cipher size\n");
538 sasl_dispose(&vs->sasl.conn);
539 vs->sasl.conn = NULL;
540 goto authabort;
542 ssf *= 8; /* tls key size is bytes, sasl wants bits */
544 err = sasl_setprop(vs->sasl.conn, SASL_SSF_EXTERNAL, &ssf);
545 if (err != SASL_OK) {
546 VNC_DEBUG("cannot set SASL external SSF %d (%s)\n",
547 err, sasl_errstring(err, NULL, NULL));
548 sasl_dispose(&vs->sasl.conn);
549 vs->sasl.conn = NULL;
550 goto authabort;
552 } else
553 #endif /* CONFIG_VNC_TLS */
554 vs->sasl.wantSSF = 1;
556 memset (&secprops, 0, sizeof secprops);
557 /* Inform SASL that we've got an external SSF layer from TLS */
558 if (strncmp(vs->vd->display, "unix:", 5) == 0
559 #ifdef CONFIG_VNC_TLS
560 /* Disable SSF, if using TLS+x509+SASL only. TLS without x509
561 is not sufficiently strong */
562 || (vs->auth == VNC_AUTH_VENCRYPT &&
563 vs->subauth == VNC_AUTH_VENCRYPT_X509SASL)
564 #endif /* CONFIG_VNC_TLS */
566 /* If we've got TLS or UNIX domain sock, we don't care about SSF */
567 secprops.min_ssf = 0;
568 secprops.max_ssf = 0;
569 secprops.maxbufsize = 8192;
570 secprops.security_flags = 0;
571 } else {
572 /* Plain TCP, better get an SSF layer */
573 secprops.min_ssf = 56; /* Good enough to require kerberos */
574 secprops.max_ssf = 100000; /* Arbitrary big number */
575 secprops.maxbufsize = 8192;
576 /* Forbid any anonymous or trivially crackable auth */
577 secprops.security_flags =
578 SASL_SEC_NOANONYMOUS | SASL_SEC_NOPLAINTEXT;
581 err = sasl_setprop(vs->sasl.conn, SASL_SEC_PROPS, &secprops);
582 if (err != SASL_OK) {
583 VNC_DEBUG("cannot set SASL security props %d (%s)\n",
584 err, sasl_errstring(err, NULL, NULL));
585 sasl_dispose(&vs->sasl.conn);
586 vs->sasl.conn = NULL;
587 goto authabort;
590 err = sasl_listmech(vs->sasl.conn,
591 NULL, /* Don't need to set user */
592 "", /* Prefix */
593 ",", /* Separator */
594 "", /* Suffix */
595 &mechlist,
596 NULL,
597 NULL);
598 if (err != SASL_OK) {
599 VNC_DEBUG("cannot list SASL mechanisms %d (%s)\n",
600 err, sasl_errdetail(vs->sasl.conn));
601 sasl_dispose(&vs->sasl.conn);
602 vs->sasl.conn = NULL;
603 goto authabort;
605 VNC_DEBUG("Available mechanisms for client: '%s'\n", mechlist);
607 vs->sasl.mechlist = g_strdup(mechlist);
608 mechlistlen = strlen(mechlist);
609 vnc_write_u32(vs, mechlistlen);
610 vnc_write(vs, mechlist, mechlistlen);
611 vnc_flush(vs);
613 VNC_DEBUG("Wait for client mechname length\n");
614 vnc_read_when(vs, protocol_client_auth_sasl_mechname_len, 4);
616 return;
618 authabort:
619 vnc_client_error(vs);