Merge tag 'qemu-macppc-20230206' of https://github.com/mcayland/qemu into staging
[qemu.git] / ui / vnc-auth-sasl.c
blob47fdae5b215b93b7ea3c9c52ce7bdeee051e9dfc
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 "qemu/osdep.h"
26 #include "qapi/error.h"
27 #include "authz/base.h"
28 #include "vnc.h"
29 #include "trace.h"
32 * Apple has deprecated sasl.h functions in OS X 10.11. Therefore,
33 * files that use SASL API need to disable -Wdeprecated-declarations.
35 #ifdef CONFIG_DARWIN
36 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
37 #endif
39 /* Max amount of data we send/recv for SASL steps to prevent DOS */
40 #define SASL_DATA_MAX_LEN (1024 * 1024)
43 bool vnc_sasl_server_init(Error **errp)
45 int saslErr = sasl_server_init(NULL, "qemu");
47 if (saslErr != SASL_OK) {
48 error_setg(errp, "Failed to initialize SASL auth: %s",
49 sasl_errstring(saslErr, NULL, NULL));
50 return false;
52 return true;
55 void vnc_sasl_client_cleanup(VncState *vs)
57 if (vs->sasl.conn) {
58 vs->sasl.runSSF = false;
59 vs->sasl.wantSSF = false;
60 vs->sasl.waitWriteSSF = 0;
61 vs->sasl.encodedLength = vs->sasl.encodedOffset = 0;
62 vs->sasl.encoded = NULL;
63 g_free(vs->sasl.username);
64 g_free(vs->sasl.mechlist);
65 vs->sasl.username = vs->sasl.mechlist = NULL;
66 sasl_dispose(&vs->sasl.conn);
67 vs->sasl.conn = NULL;
72 size_t vnc_client_write_sasl(VncState *vs)
74 size_t ret;
76 VNC_DEBUG("Write SASL: Pending output %p size %zd offset %zd "
77 "Encoded: %p size %d offset %d\n",
78 vs->output.buffer, vs->output.capacity, vs->output.offset,
79 vs->sasl.encoded, vs->sasl.encodedLength, vs->sasl.encodedOffset);
81 if (!vs->sasl.encoded) {
82 int err;
83 err = sasl_encode(vs->sasl.conn,
84 (char *)vs->output.buffer,
85 vs->output.offset,
86 (const char **)&vs->sasl.encoded,
87 &vs->sasl.encodedLength);
88 if (err != SASL_OK)
89 return vnc_client_io_error(vs, -1, NULL);
91 vs->sasl.encodedRawLength = vs->output.offset;
92 vs->sasl.encodedOffset = 0;
95 ret = vnc_client_write_buf(vs,
96 vs->sasl.encoded + vs->sasl.encodedOffset,
97 vs->sasl.encodedLength - vs->sasl.encodedOffset);
98 if (!ret)
99 return 0;
101 vs->sasl.encodedOffset += ret;
102 if (vs->sasl.encodedOffset == vs->sasl.encodedLength) {
103 bool throttled = vs->force_update_offset != 0;
104 size_t offset;
105 if (vs->sasl.encodedRawLength >= vs->force_update_offset) {
106 vs->force_update_offset = 0;
107 } else {
108 vs->force_update_offset -= vs->sasl.encodedRawLength;
110 if (throttled && vs->force_update_offset == 0) {
111 trace_vnc_client_unthrottle_forced(vs, vs->ioc);
113 offset = vs->output.offset;
114 buffer_advance(&vs->output, vs->sasl.encodedRawLength);
115 if (offset >= vs->throttle_output_offset &&
116 vs->output.offset < vs->throttle_output_offset) {
117 trace_vnc_client_unthrottle_incremental(vs, vs->ioc,
118 vs->output.offset);
120 vs->sasl.encoded = NULL;
121 vs->sasl.encodedOffset = vs->sasl.encodedLength = 0;
124 /* Can't merge this block with one above, because
125 * someone might have written more unencrypted
126 * data in vs->output while we were processing
127 * SASL encoded output
129 if (vs->output.offset == 0) {
130 if (vs->ioc_tag) {
131 g_source_remove(vs->ioc_tag);
133 vs->ioc_tag = qio_channel_add_watch(
134 vs->ioc, G_IO_IN | G_IO_HUP | G_IO_ERR,
135 vnc_client_io, vs, NULL);
138 return ret;
142 size_t vnc_client_read_sasl(VncState *vs)
144 size_t ret;
145 uint8_t encoded[4096];
146 const char *decoded;
147 unsigned int decodedLen;
148 int err;
150 ret = vnc_client_read_buf(vs, encoded, sizeof(encoded));
151 if (!ret)
152 return 0;
154 err = sasl_decode(vs->sasl.conn,
155 (char *)encoded, ret,
156 &decoded, &decodedLen);
158 if (err != SASL_OK)
159 return vnc_client_io_error(vs, -1, NULL);
160 VNC_DEBUG("Read SASL Encoded %p size %ld Decoded %p size %d\n",
161 encoded, ret, decoded, decodedLen);
162 buffer_reserve(&vs->input, decodedLen);
163 buffer_append(&vs->input, decoded, decodedLen);
164 return decodedLen;
168 static int vnc_auth_sasl_check_access(VncState *vs)
170 const void *val;
171 int rv;
172 Error *err = NULL;
173 bool allow;
175 rv = sasl_getprop(vs->sasl.conn, SASL_USERNAME, &val);
176 if (rv != SASL_OK) {
177 trace_vnc_auth_fail(vs, vs->auth, "Cannot fetch SASL username",
178 sasl_errstring(rv, NULL, NULL));
179 return -1;
181 if (val == NULL) {
182 trace_vnc_auth_fail(vs, vs->auth, "No SASL username set", "");
183 return -1;
186 vs->sasl.username = g_strdup((const char*)val);
187 trace_vnc_auth_sasl_username(vs, vs->sasl.username);
189 if (vs->vd->sasl.authzid == NULL) {
190 trace_vnc_auth_sasl_acl(vs, 1);
191 return 0;
194 allow = qauthz_is_allowed_by_id(vs->vd->sasl.authzid,
195 vs->sasl.username, &err);
196 if (err) {
197 trace_vnc_auth_fail(vs, vs->auth, "Error from authz",
198 error_get_pretty(err));
199 error_free(err);
200 return -1;
203 trace_vnc_auth_sasl_acl(vs, allow);
204 return allow ? 0 : -1;
207 static int vnc_auth_sasl_check_ssf(VncState *vs)
209 const void *val;
210 int err, ssf;
212 if (!vs->sasl.wantSSF)
213 return 1;
215 err = sasl_getprop(vs->sasl.conn, SASL_SSF, &val);
216 if (err != SASL_OK)
217 return 0;
219 ssf = *(const int *)val;
221 trace_vnc_auth_sasl_ssf(vs, ssf);
223 if (ssf < 56)
224 return 0; /* 56 is good for Kerberos */
226 /* Only setup for read initially, because we're about to send an RPC
227 * reply which must be in plain text. When the next incoming RPC
228 * arrives, we'll switch on writes too
230 * cf qemudClientReadSASL in qemud.c
232 vs->sasl.runSSF = 1;
234 /* We have a SSF that's good enough */
235 return 1;
239 * Step Msg
241 * Input from client:
243 * u32 clientin-length
244 * u8-array clientin-string
246 * Output to client:
248 * u32 serverout-length
249 * u8-array serverout-strin
250 * u8 continue
253 static int protocol_client_auth_sasl_step_len(VncState *vs, uint8_t *data, size_t len);
255 static int protocol_client_auth_sasl_step(VncState *vs, uint8_t *data, size_t len)
257 uint32_t datalen = len;
258 const char *serverout;
259 unsigned int serveroutlen;
260 int err;
261 char *clientdata = NULL;
263 /* NB, distinction of NULL vs "" is *critical* in SASL */
264 if (datalen) {
265 clientdata = (char*)data;
266 clientdata[datalen-1] = '\0'; /* Wire includes '\0', but make sure */
267 datalen--; /* Don't count NULL byte when passing to _start() */
270 err = sasl_server_step(vs->sasl.conn,
271 clientdata,
272 datalen,
273 &serverout,
274 &serveroutlen);
275 trace_vnc_auth_sasl_step(vs, data, len, serverout, serveroutlen, err);
276 if (err != SASL_OK &&
277 err != SASL_CONTINUE) {
278 trace_vnc_auth_fail(vs, vs->auth, "Cannot step SASL auth",
279 sasl_errdetail(vs->sasl.conn));
280 sasl_dispose(&vs->sasl.conn);
281 vs->sasl.conn = NULL;
282 goto authabort;
285 if (serveroutlen > SASL_DATA_MAX_LEN) {
286 trace_vnc_auth_fail(vs, vs->auth, "SASL data too long", "");
287 sasl_dispose(&vs->sasl.conn);
288 vs->sasl.conn = NULL;
289 goto authabort;
292 if (serveroutlen) {
293 vnc_write_u32(vs, serveroutlen + 1);
294 vnc_write(vs, serverout, serveroutlen + 1);
295 } else {
296 vnc_write_u32(vs, 0);
299 /* Whether auth is complete */
300 vnc_write_u8(vs, err == SASL_CONTINUE ? 0 : 1);
302 if (err == SASL_CONTINUE) {
303 /* Wait for step length */
304 vnc_read_when(vs, protocol_client_auth_sasl_step_len, 4);
305 } else {
306 if (!vnc_auth_sasl_check_ssf(vs)) {
307 trace_vnc_auth_fail(vs, vs->auth, "SASL SSF too weak", "");
308 goto authreject;
311 /* Check the username access control list */
312 if (vnc_auth_sasl_check_access(vs) < 0) {
313 goto authreject;
316 trace_vnc_auth_pass(vs, vs->auth);
317 vnc_write_u32(vs, 0); /* Accept auth */
319 * Delay writing in SSF encoded mode until pending output
320 * buffer is written
322 if (vs->sasl.runSSF)
323 vs->sasl.waitWriteSSF = vs->output.offset;
324 start_client_init(vs);
327 return 0;
329 authreject:
330 vnc_write_u32(vs, 1); /* Reject auth */
331 vnc_write_u32(vs, sizeof("Authentication failed"));
332 vnc_write(vs, "Authentication failed", sizeof("Authentication failed"));
333 vnc_flush(vs);
334 vnc_client_error(vs);
335 return -1;
337 authabort:
338 vnc_client_error(vs);
339 return -1;
342 static int protocol_client_auth_sasl_step_len(VncState *vs, uint8_t *data, size_t len)
344 uint32_t steplen = read_u32(data, 0);
346 if (steplen > SASL_DATA_MAX_LEN) {
347 trace_vnc_auth_fail(vs, vs->auth, "SASL step len too large", "");
348 vnc_client_error(vs);
349 return -1;
352 if (steplen == 0)
353 return protocol_client_auth_sasl_step(vs, NULL, 0);
354 else
355 vnc_read_when(vs, protocol_client_auth_sasl_step, steplen);
356 return 0;
360 * Start Msg
362 * Input from client:
364 * u32 clientin-length
365 * u8-array clientin-string
367 * Output to client:
369 * u32 serverout-length
370 * u8-array serverout-strin
371 * u8 continue
374 #define SASL_DATA_MAX_LEN (1024 * 1024)
376 static int protocol_client_auth_sasl_start(VncState *vs, uint8_t *data, size_t len)
378 uint32_t datalen = len;
379 const char *serverout;
380 unsigned int serveroutlen;
381 int err;
382 char *clientdata = NULL;
384 /* NB, distinction of NULL vs "" is *critical* in SASL */
385 if (datalen) {
386 clientdata = (char*)data;
387 clientdata[datalen-1] = '\0'; /* Should be on wire, but make sure */
388 datalen--; /* Don't count NULL byte when passing to _start() */
391 err = sasl_server_start(vs->sasl.conn,
392 vs->sasl.mechlist,
393 clientdata,
394 datalen,
395 &serverout,
396 &serveroutlen);
397 trace_vnc_auth_sasl_start(vs, data, len, serverout, serveroutlen, err);
398 if (err != SASL_OK &&
399 err != SASL_CONTINUE) {
400 trace_vnc_auth_fail(vs, vs->auth, "Cannot start SASL auth",
401 sasl_errdetail(vs->sasl.conn));
402 sasl_dispose(&vs->sasl.conn);
403 vs->sasl.conn = NULL;
404 goto authabort;
406 if (serveroutlen > SASL_DATA_MAX_LEN) {
407 trace_vnc_auth_fail(vs, vs->auth, "SASL data too long", "");
408 sasl_dispose(&vs->sasl.conn);
409 vs->sasl.conn = NULL;
410 goto authabort;
413 if (serveroutlen) {
414 vnc_write_u32(vs, serveroutlen + 1);
415 vnc_write(vs, serverout, serveroutlen + 1);
416 } else {
417 vnc_write_u32(vs, 0);
420 /* Whether auth is complete */
421 vnc_write_u8(vs, err == SASL_CONTINUE ? 0 : 1);
423 if (err == SASL_CONTINUE) {
424 /* Wait for step length */
425 vnc_read_when(vs, protocol_client_auth_sasl_step_len, 4);
426 } else {
427 if (!vnc_auth_sasl_check_ssf(vs)) {
428 trace_vnc_auth_fail(vs, vs->auth, "SASL SSF too weak", "");
429 goto authreject;
432 /* Check the username access control list */
433 if (vnc_auth_sasl_check_access(vs) < 0) {
434 goto authreject;
437 trace_vnc_auth_pass(vs, vs->auth);
438 vnc_write_u32(vs, 0); /* Accept auth */
439 start_client_init(vs);
442 return 0;
444 authreject:
445 vnc_write_u32(vs, 1); /* Reject auth */
446 vnc_write_u32(vs, sizeof("Authentication failed"));
447 vnc_write(vs, "Authentication failed", sizeof("Authentication failed"));
448 vnc_flush(vs);
449 vnc_client_error(vs);
450 return -1;
452 authabort:
453 vnc_client_error(vs);
454 return -1;
457 static int protocol_client_auth_sasl_start_len(VncState *vs, uint8_t *data, size_t len)
459 uint32_t startlen = read_u32(data, 0);
461 if (startlen > SASL_DATA_MAX_LEN) {
462 trace_vnc_auth_fail(vs, vs->auth, "SASL start len too large", "");
463 vnc_client_error(vs);
464 return -1;
467 if (startlen == 0)
468 return protocol_client_auth_sasl_start(vs, NULL, 0);
470 vnc_read_when(vs, protocol_client_auth_sasl_start, startlen);
471 return 0;
474 static int protocol_client_auth_sasl_mechname(VncState *vs, uint8_t *data, size_t len)
476 char *mechname = g_strndup((const char *) data, len);
477 trace_vnc_auth_sasl_mech_choose(vs, mechname);
479 if (strncmp(vs->sasl.mechlist, mechname, len) == 0) {
480 if (vs->sasl.mechlist[len] != '\0' &&
481 vs->sasl.mechlist[len] != ',') {
482 goto fail;
484 } else {
485 char *offset = strstr(vs->sasl.mechlist, mechname);
486 if (!offset) {
487 goto fail;
489 if (offset[-1] != ',' ||
490 (offset[len] != '\0'&&
491 offset[len] != ',')) {
492 goto fail;
496 g_free(vs->sasl.mechlist);
497 vs->sasl.mechlist = mechname;
499 vnc_read_when(vs, protocol_client_auth_sasl_start_len, 4);
500 return 0;
502 fail:
503 trace_vnc_auth_fail(vs, vs->auth, "Unsupported mechname", mechname);
504 vnc_client_error(vs);
505 g_free(mechname);
506 return -1;
509 static int protocol_client_auth_sasl_mechname_len(VncState *vs, uint8_t *data, size_t len)
511 uint32_t mechlen = read_u32(data, 0);
513 if (mechlen > 100) {
514 trace_vnc_auth_fail(vs, vs->auth, "SASL mechname too long", "");
515 vnc_client_error(vs);
516 return -1;
518 if (mechlen < 1) {
519 trace_vnc_auth_fail(vs, vs->auth, "SASL mechname too short", "");
520 vnc_client_error(vs);
521 return -1;
523 vnc_read_when(vs, protocol_client_auth_sasl_mechname,mechlen);
524 return 0;
527 static char *
528 vnc_socket_ip_addr_string(QIOChannelSocket *ioc,
529 bool local,
530 Error **errp)
532 SocketAddress *addr;
533 char *ret;
535 if (local) {
536 addr = qio_channel_socket_get_local_address(ioc, errp);
537 } else {
538 addr = qio_channel_socket_get_remote_address(ioc, errp);
540 if (!addr) {
541 return NULL;
544 if (addr->type != SOCKET_ADDRESS_TYPE_INET) {
545 error_setg(errp, "Not an inet socket type");
546 qapi_free_SocketAddress(addr);
547 return NULL;
549 ret = g_strdup_printf("%s;%s", addr->u.inet.host, addr->u.inet.port);
550 qapi_free_SocketAddress(addr);
551 return ret;
554 void start_auth_sasl(VncState *vs)
556 const char *mechlist = NULL;
557 sasl_security_properties_t secprops;
558 int err;
559 Error *local_err = NULL;
560 char *localAddr, *remoteAddr;
561 int mechlistlen;
563 /* Get local & remote client addresses in form IPADDR;PORT */
564 localAddr = vnc_socket_ip_addr_string(vs->sioc, true, &local_err);
565 if (!localAddr) {
566 trace_vnc_auth_fail(vs, vs->auth, "Cannot format local IP",
567 error_get_pretty(local_err));
568 goto authabort;
571 remoteAddr = vnc_socket_ip_addr_string(vs->sioc, false, &local_err);
572 if (!remoteAddr) {
573 trace_vnc_auth_fail(vs, vs->auth, "Cannot format remote IP",
574 error_get_pretty(local_err));
575 g_free(localAddr);
576 goto authabort;
579 err = sasl_server_new("vnc",
580 NULL, /* FQDN - just delegates to gethostname */
581 NULL, /* User realm */
582 localAddr,
583 remoteAddr,
584 NULL, /* Callbacks, not needed */
585 SASL_SUCCESS_DATA,
586 &vs->sasl.conn);
587 g_free(localAddr);
588 g_free(remoteAddr);
589 localAddr = remoteAddr = NULL;
591 if (err != SASL_OK) {
592 trace_vnc_auth_fail(vs, vs->auth, "SASL context setup failed",
593 sasl_errstring(err, NULL, NULL));
594 vs->sasl.conn = NULL;
595 goto authabort;
598 /* Inform SASL that we've got an external SSF layer from TLS/x509 */
599 if (vs->auth == VNC_AUTH_VENCRYPT &&
600 vs->subauth == VNC_AUTH_VENCRYPT_X509SASL) {
601 int keysize;
602 sasl_ssf_t ssf;
604 keysize = qcrypto_tls_session_get_key_size(vs->tls,
605 &local_err);
606 if (keysize < 0) {
607 trace_vnc_auth_fail(vs, vs->auth, "cannot TLS get cipher size",
608 error_get_pretty(local_err));
609 sasl_dispose(&vs->sasl.conn);
610 vs->sasl.conn = NULL;
611 goto authabort;
613 ssf = keysize * CHAR_BIT; /* tls key size is bytes, sasl wants bits */
615 err = sasl_setprop(vs->sasl.conn, SASL_SSF_EXTERNAL, &ssf);
616 if (err != SASL_OK) {
617 trace_vnc_auth_fail(vs, vs->auth, "cannot set SASL external SSF",
618 sasl_errstring(err, NULL, NULL));
619 sasl_dispose(&vs->sasl.conn);
620 vs->sasl.conn = NULL;
621 goto authabort;
623 } else {
624 vs->sasl.wantSSF = 1;
627 memset (&secprops, 0, sizeof secprops);
628 /* Inform SASL that we've got an external SSF layer from TLS.
630 * Disable SSF, if using TLS+x509+SASL only. TLS without x509
631 * is not sufficiently strong
633 if (vs->vd->is_unix ||
634 (vs->auth == VNC_AUTH_VENCRYPT &&
635 vs->subauth == VNC_AUTH_VENCRYPT_X509SASL)) {
636 /* If we've got TLS or UNIX domain sock, we don't care about SSF */
637 secprops.min_ssf = 0;
638 secprops.max_ssf = 0;
639 secprops.maxbufsize = 8192;
640 secprops.security_flags = 0;
641 } else {
642 /* Plain TCP, better get an SSF layer */
643 secprops.min_ssf = 56; /* Good enough to require kerberos */
644 secprops.max_ssf = 100000; /* Arbitrary big number */
645 secprops.maxbufsize = 8192;
646 /* Forbid any anonymous or trivially crackable auth */
647 secprops.security_flags =
648 SASL_SEC_NOANONYMOUS | SASL_SEC_NOPLAINTEXT;
651 err = sasl_setprop(vs->sasl.conn, SASL_SEC_PROPS, &secprops);
652 if (err != SASL_OK) {
653 trace_vnc_auth_fail(vs, vs->auth, "cannot set SASL security props",
654 sasl_errstring(err, NULL, NULL));
655 sasl_dispose(&vs->sasl.conn);
656 vs->sasl.conn = NULL;
657 goto authabort;
660 err = sasl_listmech(vs->sasl.conn,
661 NULL, /* Don't need to set user */
662 "", /* Prefix */
663 ",", /* Separator */
664 "", /* Suffix */
665 &mechlist,
666 NULL,
667 NULL);
668 if (err != SASL_OK) {
669 trace_vnc_auth_fail(vs, vs->auth, "cannot list SASL mechanisms",
670 sasl_errdetail(vs->sasl.conn));
671 sasl_dispose(&vs->sasl.conn);
672 vs->sasl.conn = NULL;
673 goto authabort;
675 trace_vnc_auth_sasl_mech_list(vs, mechlist);
677 vs->sasl.mechlist = g_strdup(mechlist);
678 mechlistlen = strlen(mechlist);
679 vnc_write_u32(vs, mechlistlen);
680 vnc_write(vs, mechlist, mechlistlen);
681 vnc_flush(vs);
683 vnc_read_when(vs, protocol_client_auth_sasl_mechname_len, 4);
685 return;
687 authabort:
688 error_free(local_err);
689 vnc_client_error(vs);