Annotation of src/usr.bin/ssh/gss-serv.c, Revision 1.21
1.21 ! djm 1: /* $OpenBSD: gss-serv.c,v 1.20 2006/08/03 03:34:42 deraadt 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:
1.20 deraadt 27: #include <sys/types.h>
1.21 ! djm 28: #include <sys/param.h>
1.1 markus 29:
30: #ifdef GSSAPI
1.19 stevesk 31:
32: #include <string.h>
1.1 markus 33:
1.20 deraadt 34: #include "xmalloc.h"
35: #include "buffer.h"
36: #include "key.h"
37: #include "hostfile.h"
1.1 markus 38: #include "auth.h"
39: #include "log.h"
40: #include "channels.h"
41: #include "session.h"
1.17 djm 42: #include "misc.h"
1.1 markus 43:
44: #include "ssh-gss.h"
45:
46: static ssh_gssapi_client gssapi_client =
47: { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
48: GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}};
49:
50: ssh_gssapi_mech gssapi_null_mech =
51: { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
52:
53: #ifdef KRB5
54: extern ssh_gssapi_mech gssapi_kerberos_mech;
55: #endif
56:
57: ssh_gssapi_mech* supported_mechs[]= {
58: #ifdef KRB5
59: &gssapi_kerberos_mech,
60: #endif
61: &gssapi_null_mech,
62: };
1.21 ! djm 63:
! 64:
! 65: /*
! 66: * Acquire credentials for a server running on the current host.
! 67: * Requires that the context structure contains a valid OID
! 68: */
! 69:
! 70: /* Returns a GSSAPI error code */
! 71: /* Privileged (called from ssh_gssapi_server_ctx) */
! 72: static OM_uint32
! 73: ssh_gssapi_acquire_cred(Gssctxt *ctx)
! 74: {
! 75: OM_uint32 status;
! 76: char lname[MAXHOSTNAMELEN];
! 77: gss_OID_set oidset;
! 78:
! 79: gss_create_empty_oid_set(&status, &oidset);
! 80: gss_add_oid_set_member(&status, ctx->oid, &oidset);
! 81:
! 82: if (gethostname(lname, MAXHOSTNAMELEN)) {
! 83: gss_release_oid_set(&status, &oidset);
! 84: return (-1);
! 85: }
! 86:
! 87: if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) {
! 88: gss_release_oid_set(&status, &oidset);
! 89: return (ctx->major);
! 90: }
! 91:
! 92: if ((ctx->major = gss_acquire_cred(&ctx->minor,
! 93: ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds, NULL, NULL)))
! 94: ssh_gssapi_error(ctx);
! 95:
! 96: gss_release_oid_set(&status, &oidset);
! 97: return (ctx->major);
! 98: }
! 99:
! 100: /* Privileged */
! 101: OM_uint32
! 102: ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid)
! 103: {
! 104: if (*ctx)
! 105: ssh_gssapi_delete_ctx(ctx);
! 106: ssh_gssapi_build_ctx(ctx);
! 107: ssh_gssapi_set_oid(*ctx, oid);
! 108: return (ssh_gssapi_acquire_cred(*ctx));
! 109: }
1.1 markus 110:
1.11 stevesk 111: /* Unprivileged */
1.1 markus 112: void
113: ssh_gssapi_supported_oids(gss_OID_set *oidset)
114: {
115: int i = 0;
116: OM_uint32 min_status;
117: int present;
118: gss_OID_set supported;
119:
120: gss_create_empty_oid_set(&min_status, oidset);
121: gss_indicate_mechs(&min_status, &supported);
122:
123: while (supported_mechs[i]->name != NULL) {
124: if (GSS_ERROR(gss_test_oid_set_member(&min_status,
125: &supported_mechs[i]->oid, supported, &present)))
126: present = 0;
127: if (present)
128: gss_add_oid_set_member(&min_status,
129: &supported_mechs[i]->oid, oidset);
130: i++;
131: }
1.15 djm 132:
133: gss_release_oid_set(&min_status, &supported);
1.1 markus 134: }
135:
136:
137: /* Wrapper around accept_sec_context
138: * Requires that the context contains:
139: * oid
140: * credentials (from ssh_gssapi_acquire_cred)
141: */
1.11 stevesk 142: /* Privileged */
1.1 markus 143: OM_uint32
144: ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok,
145: gss_buffer_desc *send_tok, OM_uint32 *flags)
146: {
147: OM_uint32 status;
148: gss_OID mech;
149:
150: ctx->major = gss_accept_sec_context(&ctx->minor,
151: &ctx->context, ctx->creds, recv_tok,
152: GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
153: send_tok, flags, NULL, &ctx->client_creds);
154:
155: if (GSS_ERROR(ctx->major))
156: ssh_gssapi_error(ctx);
157:
158: if (ctx->client_creds)
159: debug("Received some client credentials");
160: else
161: debug("Got no client credentials");
162:
163: status = ctx->major;
164:
165: /* Now, if we're complete and we have the right flags, then
166: * we flag the user as also having been authenticated
167: */
168:
169: if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) &&
170: (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
171: if (ssh_gssapi_getclient(ctx, &gssapi_client))
172: fatal("Couldn't convert client name");
173: }
174:
175: return (status);
176: }
177:
178: /*
179: * This parses an exported name, extracting the mechanism specific portion
180: * to use for ACL checking. It verifies that the name belongs the mechanism
181: * originally selected.
182: */
183: static OM_uint32
184: ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
185: {
1.6 djm 186: u_char *tok;
1.1 markus 187: OM_uint32 offset;
188: OM_uint32 oidl;
1.3 markus 189:
1.13 stevesk 190: tok = ename->value;
1.3 markus 191:
192: /*
193: * Check that ename is long enough for all of the fixed length
1.1 markus 194: * header, and that the initial ID bytes are correct
195: */
196:
1.13 stevesk 197: if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0)
1.1 markus 198: return GSS_S_FAILURE;
199:
200: /*
201: * Extract the OID, and check it. Here GSSAPI breaks with tradition
202: * and does use the OID type and length bytes. To confuse things
203: * there are two lengths - the first including these, and the
204: * second without.
205: */
206:
1.17 djm 207: oidl = get_u16(tok+2); /* length including next two bytes */
1.1 markus 208: oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
209:
210: /*
211: * Check the BER encoding for correct type and length, that the
212: * string is long enough and that the OID matches that in our context
213: */
214: if (tok[4] != 0x06 || tok[5] != oidl ||
1.3 markus 215: ename->length < oidl+6 ||
1.13 stevesk 216: !ssh_gssapi_check_oid(ctx, tok+6, oidl))
1.1 markus 217: return GSS_S_FAILURE;
218:
219: offset = oidl+6;
1.3 markus 220:
1.1 markus 221: if (ename->length < offset+4)
222: return GSS_S_FAILURE;
1.3 markus 223:
1.17 djm 224: name->length = get_u32(tok+offset);
1.1 markus 225: offset += 4;
1.3 markus 226:
1.1 markus 227: if (ename->length < offset+name->length)
1.3 markus 228: return GSS_S_FAILURE;
229:
1.2 markus 230: name->value = xmalloc(name->length+1);
1.14 stevesk 231: memcpy(name->value, tok+offset, name->length);
1.2 markus 232: ((char *)name->value)[name->length] = 0;
233:
1.1 markus 234: return GSS_S_COMPLETE;
1.3 markus 235: }
1.1 markus 236:
237: /* Extract the client details from a given context. This can only reliably
238: * be called once for a context */
239:
1.11 stevesk 240: /* Privileged (called from accept_secure_ctx) */
1.1 markus 241: OM_uint32
242: ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
243: {
244: int i = 0;
245:
246: gss_buffer_desc ename;
1.3 markus 247:
1.1 markus 248: client->mech = NULL;
249:
250: while (supported_mechs[i]->name != NULL) {
251: if (supported_mechs[i]->oid.length == ctx->oid->length &&
252: (memcmp(supported_mechs[i]->oid.elements,
253: ctx->oid->elements, ctx->oid->length) == 0))
254: client->mech = supported_mechs[i];
255: i++;
256: }
257:
1.3 markus 258: if (client->mech == NULL)
1.1 markus 259: return GSS_S_FAILURE;
1.3 markus 260:
261: if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
1.1 markus 262: &client->displayname, NULL))) {
1.3 markus 263: ssh_gssapi_error(ctx);
264: return (ctx->major);
1.1 markus 265: }
1.3 markus 266:
267: if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
1.1 markus 268: &ename))) {
269: ssh_gssapi_error(ctx);
270: return (ctx->major);
271: }
1.3 markus 272:
1.1 markus 273: if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
274: &client->exportedname))) {
275: return (ctx->major);
276: }
277:
278: /* We can't copy this structure, so we just move the pointer to it */
279: client->creds = ctx->client_creds;
280: ctx->client_creds = GSS_C_NO_CREDENTIAL;
281: return (ctx->major);
282: }
283:
1.4 markus 284: /* As user - called on fatal/exit */
1.1 markus 285: void
1.4 markus 286: ssh_gssapi_cleanup_creds(void)
1.1 markus 287: {
288: if (gssapi_client.store.filename != NULL) {
289: /* Unlink probably isn't sufficient */
1.14 stevesk 290: debug("removing gssapi cred file\"%s\"",
291: gssapi_client.store.filename);
1.1 markus 292: unlink(gssapi_client.store.filename);
293: }
294: }
295:
296: /* As user */
297: void
298: ssh_gssapi_storecreds(void)
299: {
300: if (gssapi_client.mech && gssapi_client.mech->storecreds) {
301: (*gssapi_client.mech->storecreds)(&gssapi_client);
302: } else
303: debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
304: }
305:
306: /* This allows GSSAPI methods to do things to the childs environment based
307: * on the passed authentication process and credentials.
308: */
309: /* As user */
310: void
311: ssh_gssapi_do_child(char ***envp, u_int *envsizep)
312: {
313:
314: if (gssapi_client.store.envvar != NULL &&
315: gssapi_client.store.envval != NULL) {
316: debug("Setting %s to %s", gssapi_client.store.envvar,
1.13 stevesk 317: gssapi_client.store.envval);
1.1 markus 318: child_set_env(envp, envsizep, gssapi_client.store.envvar,
1.7 djm 319: gssapi_client.store.envval);
1.1 markus 320: }
321: }
322:
1.9 djm 323: /* Privileged */
1.1 markus 324: int
325: ssh_gssapi_userok(char *user)
326: {
1.8 djm 327: OM_uint32 lmin;
328:
1.1 markus 329: if (gssapi_client.exportedname.length == 0 ||
330: gssapi_client.exportedname.value == NULL) {
331: debug("No suitable client data");
332: return 0;
333: }
334: if (gssapi_client.mech && gssapi_client.mech->userok)
1.8 djm 335: if ((*gssapi_client.mech->userok)(&gssapi_client, user))
336: return 1;
337: else {
338: /* Destroy delegated credentials if userok fails */
339: gss_release_buffer(&lmin, &gssapi_client.displayname);
340: gss_release_buffer(&lmin, &gssapi_client.exportedname);
341: gss_release_cred(&lmin, &gssapi_client.creds);
342: memset(&gssapi_client, 0, sizeof(ssh_gssapi_client));
343: return 0;
344: }
1.1 markus 345: else
346: debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
347: return (0);
1.5 markus 348: }
349:
1.11 stevesk 350: /* Privileged */
1.5 markus 351: OM_uint32
352: ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
353: {
354: ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
355: gssbuf, gssmic, NULL);
356:
357: return (ctx->major);
1.1 markus 358: }
359:
360: #endif
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