Annotation of src/usr.bin/ssh/auth2-gss.c, Revision 1.34
1.34 ! djm 1: /* $OpenBSD: auth2-gss.c,v 1.33 2021/12/19 22:12:07 djm Exp $ */
1.1 markus 2:
3: /*
4: * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
5: *
6: * Redistribution and use in source and binary forms, with or without
7: * modification, are permitted provided that the following conditions
8: * are met:
9: * 1. Redistributions of source code must retain the above copyright
10: * notice, this list of conditions and the following disclaimer.
11: * 2. Redistributions in binary form must reproduce the above copyright
12: * notice, this list of conditions and the following disclaimer in the
13: * documentation and/or other materials provided with the distribution.
14: *
15: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AS IS'' AND ANY EXPRESS OR
16: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25: */
26:
1.16 dtucker 27: #ifdef GSSAPI
28:
1.15 deraadt 29: #include <sys/types.h>
1.1 markus 30:
1.15 deraadt 31: #include "xmalloc.h"
1.27 markus 32: #include "sshkey.h"
1.15 deraadt 33: #include "hostfile.h"
1.1 markus 34: #include "auth.h"
35: #include "ssh2.h"
36: #include "log.h"
37: #include "dispatch.h"
1.27 markus 38: #include "sshbuf.h"
39: #include "ssherr.h"
1.1 markus 40: #include "servconf.h"
41: #include "packet.h"
1.32 djm 42: #include "kex.h"
1.15 deraadt 43: #include "ssh-gss.h"
1.1 markus 44: #include "monitor_wrap.h"
45:
1.34 ! djm 46: #define SSH_GSSAPI_MAX_MECHS 2048
! 47:
1.1 markus 48: extern ServerOptions options;
49:
1.24 markus 50: static int input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh);
51: static int input_gssapi_mic(int type, u_int32_t plen, struct ssh *ssh);
52: static int input_gssapi_exchange_complete(int type, u_int32_t plen, struct ssh *ssh);
53: static int input_gssapi_errtok(int, u_int32_t, struct ssh *);
1.1 markus 54:
55: /*
56: * We only support those mechanisms that we know about (ie ones that we know
1.12 stevesk 57: * how to check local user kuserok and the like)
1.1 markus 58: */
59: static int
1.33 djm 60: userauth_gssapi(struct ssh *ssh, const char *method)
1.1 markus 61: {
1.25 markus 62: Authctxt *authctxt = ssh->authctxt;
1.8 avsm 63: gss_OID_desc goid = {0, NULL};
1.1 markus 64: Gssctxt *ctxt = NULL;
1.27 markus 65: int r, present;
66: u_int mechs;
1.1 markus 67: OM_uint32 ms;
1.27 markus 68: size_t len;
1.9 djm 69: u_char *doid = NULL;
1.1 markus 70:
1.27 markus 71: if ((r = sshpkt_get_u32(ssh, &mechs)) != 0)
1.30 djm 72: fatal_fr(r, "parse packet");
1.27 markus 73:
1.1 markus 74: if (mechs == 0) {
1.34 ! djm 75: logit_f("mechanism negotiation is not supported");
! 76: return (0);
! 77: } else if (mechs > SSH_GSSAPI_MAX_MECHS) {
! 78: logit_f("too many mechanisms requested %u > %u", mechs,
! 79: SSH_GSSAPI_MAX_MECHS);
1.1 markus 80: return (0);
81: }
82:
83: do {
84: mechs--;
85:
1.20 djm 86: free(doid);
1.1 markus 87:
1.5 markus 88: present = 0;
1.27 markus 89: if ((r = sshpkt_get_string(ssh, &doid, &len)) != 0)
1.30 djm 90: fatal_fr(r, "parse oid");
1.1 markus 91:
1.10 djm 92: if (len > 2 && doid[0] == SSH_GSS_OIDTYPE &&
93: doid[1] == len - 2) {
1.8 avsm 94: goid.elements = doid + 2;
95: goid.length = len - 2;
1.21 djm 96: ssh_gssapi_test_oid_supported(&ms, &goid, &present);
1.1 markus 97: } else {
1.34 ! djm 98: logit_f("badly formed OID received");
1.1 markus 99: }
100: } while (mechs > 0 && !present);
101:
102: if (!present) {
1.20 djm 103: free(doid);
1.17 djm 104: authctxt->server_caused_failure = 1;
1.29 djm 105: return (0);
106: }
107:
108: if (!authctxt->valid || authctxt->user == NULL) {
1.30 djm 109: debug2_f("disabled because of invalid user");
1.29 djm 110: free(doid);
1.1 markus 111: return (0);
112: }
113:
1.8 avsm 114: if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
1.13 djm 115: if (ctxt != NULL)
116: ssh_gssapi_delete_ctx(&ctxt);
1.20 djm 117: free(doid);
1.17 djm 118: authctxt->server_caused_failure = 1;
1.1 markus 119: return (0);
1.3 markus 120: }
1.1 markus 121:
1.12 stevesk 122: authctxt->methoddata = (void *)ctxt;
1.1 markus 123:
1.5 markus 124: /* Return the OID that we received */
1.27 markus 125: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE)) != 0 ||
126: (r = sshpkt_put_string(ssh, doid, len)) != 0 ||
127: (r = sshpkt_send(ssh)) != 0)
1.30 djm 128: fatal_fr(r, "send packet");
1.1 markus 129:
1.20 djm 130: free(doid);
1.1 markus 131:
1.25 markus 132: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
133: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
1.1 markus 134: authctxt->postponed = 1;
135:
136: return (0);
137: }
138:
1.22 markus 139: static int
1.24 markus 140: input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh)
1.1 markus 141: {
1.23 markus 142: Authctxt *authctxt = ssh->authctxt;
1.1 markus 143: Gssctxt *gssctxt;
144: gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
145: gss_buffer_desc recv_tok;
1.6 markus 146: OM_uint32 maj_status, min_status, flags;
1.27 markus 147: u_char *p;
148: size_t len;
149: int r;
1.1 markus 150:
151: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
152: fatal("No authentication or GSSAPI context");
153:
154: gssctxt = authctxt->methoddata;
1.27 markus 155: if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
156: (r = sshpkt_get_end(ssh)) != 0)
1.30 djm 157: fatal_fr(r, "parse packet");
1.1 markus 158:
1.27 markus 159: recv_tok.value = p;
160: recv_tok.length = len;
1.1 markus 161: maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
1.6 markus 162: &send_tok, &flags));
1.1 markus 163:
1.27 markus 164: free(p);
1.1 markus 165:
166: if (GSS_ERROR(maj_status)) {
167: if (send_tok.length != 0) {
1.27 markus 168: if ((r = sshpkt_start(ssh,
169: SSH2_MSG_USERAUTH_GSSAPI_ERRTOK)) != 0 ||
170: (r = sshpkt_put_string(ssh, send_tok.value,
171: send_tok.length)) != 0 ||
172: (r = sshpkt_send(ssh)) != 0)
1.30 djm 173: fatal_fr(r, "send ERRTOK packet");
1.1 markus 174: }
175: authctxt->postponed = 0;
1.25 markus 176: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
177: userauth_finish(ssh, 0, "gssapi-with-mic", NULL);
1.1 markus 178: } else {
179: if (send_tok.length != 0) {
1.27 markus 180: if ((r = sshpkt_start(ssh,
181: SSH2_MSG_USERAUTH_GSSAPI_TOKEN)) != 0 ||
182: (r = sshpkt_put_string(ssh, send_tok.value,
183: send_tok.length)) != 0 ||
184: (r = sshpkt_send(ssh)) != 0)
1.30 djm 185: fatal_fr(r, "send TOKEN packet");
1.1 markus 186: }
187: if (maj_status == GSS_S_COMPLETE) {
1.25 markus 188: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
1.6 markus 189: if (flags & GSS_C_INTEG_FLAG)
1.25 markus 190: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_MIC,
1.6 markus 191: &input_gssapi_mic);
192: else
1.25 markus 193: ssh_dispatch_set(ssh,
1.6 markus 194: SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
195: &input_gssapi_exchange_complete);
1.1 markus 196: }
197: }
198:
199: gss_release_buffer(&min_status, &send_tok);
1.22 markus 200: return 0;
1.1 markus 201: }
202:
1.22 markus 203: static int
1.24 markus 204: input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh)
1.1 markus 205: {
1.23 markus 206: Authctxt *authctxt = ssh->authctxt;
1.1 markus 207: Gssctxt *gssctxt;
208: gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
209: gss_buffer_desc recv_tok;
210: OM_uint32 maj_status;
1.27 markus 211: int r;
1.28 djm 212: u_char *p;
213: size_t len;
1.1 markus 214:
215: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
216: fatal("No authentication or GSSAPI context");
217:
218: gssctxt = authctxt->methoddata;
1.28 djm 219: if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
1.27 markus 220: (r = sshpkt_get_end(ssh)) != 0)
1.30 djm 221: fatal_fr(r, "parse packet");
1.28 djm 222: recv_tok.value = p;
223: recv_tok.length = len;
1.1 markus 224:
225: /* Push the error token into GSSAPI to see what it says */
226: maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
227: &send_tok, NULL));
228:
1.20 djm 229: free(recv_tok.value);
1.1 markus 230:
231: /* We can't return anything to the client, even if we wanted to */
1.25 markus 232: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
233: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
1.1 markus 234:
235: /* The client will have already moved on to the next auth */
236:
237: gss_release_buffer(&maj_status, &send_tok);
1.22 markus 238: return 0;
1.1 markus 239: }
240:
241: /*
242: * This is called when the client thinks we've completed authentication.
243: * It should only be enabled in the dispatch handler by the function above,
244: * which only enables it once the GSSAPI exchange is complete.
245: */
246:
1.22 markus 247: static int
1.24 markus 248: input_gssapi_exchange_complete(int type, u_int32_t plen, struct ssh *ssh)
1.1 markus 249: {
1.23 markus 250: Authctxt *authctxt = ssh->authctxt;
1.28 djm 251: int r, authenticated;
1.26 djm 252: const char *displayname;
1.1 markus 253:
254: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
255: fatal("No authentication or GSSAPI context");
256:
257: /*
1.6 markus 258: * We don't need to check the status, because we're only enabled in
259: * the dispatcher once the exchange is complete
1.1 markus 260: */
261:
1.27 markus 262: if ((r = sshpkt_get_end(ssh)) != 0)
1.30 djm 263: fatal_fr(r, "parse packet");
1.1 markus 264:
265: authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
266:
1.26 djm 267: if ((!use_privsep || mm_is_monitor()) &&
268: (displayname = ssh_gssapi_displayname()) != NULL)
269: auth2_record_info(authctxt, "%s", displayname);
270:
1.1 markus 271: authctxt->postponed = 0;
1.25 markus 272: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
273: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
274: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
275: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
276: userauth_finish(ssh, authenticated, "gssapi-with-mic", NULL);
1.22 markus 277: return 0;
1.6 markus 278: }
279:
1.22 markus 280: static int
1.24 markus 281: input_gssapi_mic(int type, u_int32_t plen, struct ssh *ssh)
1.6 markus 282: {
1.23 markus 283: Authctxt *authctxt = ssh->authctxt;
1.6 markus 284: Gssctxt *gssctxt;
1.27 markus 285: int r, authenticated = 0;
286: struct sshbuf *b;
1.6 markus 287: gss_buffer_desc mic, gssbuf;
1.26 djm 288: const char *displayname;
1.28 djm 289: u_char *p;
290: size_t len;
1.7 djm 291:
1.6 markus 292: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
293: fatal("No authentication or GSSAPI context");
1.7 djm 294:
1.6 markus 295: gssctxt = authctxt->methoddata;
1.7 djm 296:
1.28 djm 297: if ((r = sshpkt_get_string(ssh, &p, &len)) != 0)
1.30 djm 298: fatal_fr(r, "parse packet");
1.27 markus 299: if ((b = sshbuf_new()) == NULL)
1.30 djm 300: fatal_f("sshbuf_new failed");
1.28 djm 301: mic.value = p;
302: mic.length = len;
1.27 markus 303: ssh_gssapi_buildmic(b, authctxt->user, authctxt->service,
1.31 djm 304: "gssapi-with-mic", ssh->kex->session_id);
1.7 djm 305:
1.27 markus 306: if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL)
1.30 djm 307: fatal_f("sshbuf_mutable_ptr failed");
1.27 markus 308: gssbuf.length = sshbuf_len(b);
1.7 djm 309:
1.6 markus 310: if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
311: authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
312: else
313: logit("GSSAPI MIC check failed");
314:
1.27 markus 315: sshbuf_free(b);
1.20 djm 316: free(mic.value);
1.26 djm 317:
318: if ((!use_privsep || mm_is_monitor()) &&
319: (displayname = ssh_gssapi_displayname()) != NULL)
320: auth2_record_info(authctxt, "%s", displayname);
1.7 djm 321:
1.6 markus 322: authctxt->postponed = 0;
1.25 markus 323: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
324: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
325: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
326: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
327: userauth_finish(ssh, authenticated, "gssapi-with-mic", NULL);
1.22 markus 328: return 0;
1.1 markus 329: }
330:
331: Authmethod method_gssapi = {
1.6 markus 332: "gssapi-with-mic",
1.33 djm 333: NULL,
1.1 markus 334: userauth_gssapi,
335: &options.gss_authentication
336: };
1.16 dtucker 337: #endif
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