Annotation of src/usr.bin/ssh/gss-serv.c, Revision 1.5
1.5 ! markus 1: /* $OpenBSD: gss-serv.c,v 1.4 2003/09/23 20:17:11 markus 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:
27: #include "includes.h"
28:
29: #ifdef GSSAPI
30:
31: #include "bufaux.h"
32: #include "compat.h"
33: #include "auth.h"
34: #include "log.h"
35: #include "channels.h"
36: #include "session.h"
37: #include "servconf.h"
38: #include "monitor_wrap.h"
39: #include "xmalloc.h"
40: #include "getput.h"
41:
42: #include "ssh-gss.h"
43:
44: extern ServerOptions options;
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: };
63:
64: /* Unpriviledged */
65: void
66: ssh_gssapi_supported_oids(gss_OID_set *oidset)
67: {
68: int i = 0;
69: OM_uint32 min_status;
70: int present;
71: gss_OID_set supported;
72:
73: gss_create_empty_oid_set(&min_status, oidset);
74: gss_indicate_mechs(&min_status, &supported);
75:
76: while (supported_mechs[i]->name != NULL) {
77: if (GSS_ERROR(gss_test_oid_set_member(&min_status,
78: &supported_mechs[i]->oid, supported, &present)))
79: present = 0;
80: if (present)
81: gss_add_oid_set_member(&min_status,
82: &supported_mechs[i]->oid, oidset);
83: i++;
84: }
85: }
86:
87:
88: /* Wrapper around accept_sec_context
89: * Requires that the context contains:
90: * oid
91: * credentials (from ssh_gssapi_acquire_cred)
92: */
93: /* Priviledged */
94: OM_uint32
95: ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok,
96: gss_buffer_desc *send_tok, OM_uint32 *flags)
97: {
98: OM_uint32 status;
99: gss_OID mech;
100:
101: ctx->major = gss_accept_sec_context(&ctx->minor,
102: &ctx->context, ctx->creds, recv_tok,
103: GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
104: send_tok, flags, NULL, &ctx->client_creds);
105:
106: if (GSS_ERROR(ctx->major))
107: ssh_gssapi_error(ctx);
108:
109: if (ctx->client_creds)
110: debug("Received some client credentials");
111: else
112: debug("Got no client credentials");
113:
114: status = ctx->major;
115:
116: /* Now, if we're complete and we have the right flags, then
117: * we flag the user as also having been authenticated
118: */
119:
120: if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) &&
121: (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
122: if (ssh_gssapi_getclient(ctx, &gssapi_client))
123: fatal("Couldn't convert client name");
124: }
125:
126: return (status);
127: }
128:
129: /*
130: * This parses an exported name, extracting the mechanism specific portion
131: * to use for ACL checking. It verifies that the name belongs the mechanism
132: * originally selected.
133: */
134: static OM_uint32
135: ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
136: {
137: char *tok;
138: OM_uint32 offset;
139: OM_uint32 oidl;
1.3 markus 140:
1.1 markus 141: tok=ename->value;
1.3 markus 142:
143: /*
144: * Check that ename is long enough for all of the fixed length
1.1 markus 145: * header, and that the initial ID bytes are correct
146: */
147:
1.3 markus 148: if (ename->length<6 || memcmp(tok,"\x04\x01", 2)!=0)
1.1 markus 149: return GSS_S_FAILURE;
150:
151: /*
152: * Extract the OID, and check it. Here GSSAPI breaks with tradition
153: * and does use the OID type and length bytes. To confuse things
154: * there are two lengths - the first including these, and the
155: * second without.
156: */
157:
158: oidl = GET_16BIT(tok+2); /* length including next two bytes */
159: oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
160:
161: /*
162: * Check the BER encoding for correct type and length, that the
163: * string is long enough and that the OID matches that in our context
164: */
165: if (tok[4] != 0x06 || tok[5] != oidl ||
1.3 markus 166: ename->length < oidl+6 ||
1.1 markus 167: !ssh_gssapi_check_oid(ctx,tok+6,oidl))
168: return GSS_S_FAILURE;
169:
170: offset = oidl+6;
1.3 markus 171:
1.1 markus 172: if (ename->length < offset+4)
173: return GSS_S_FAILURE;
1.3 markus 174:
1.1 markus 175: name->length = GET_32BIT(tok+offset);
176: offset += 4;
1.3 markus 177:
1.1 markus 178: if (ename->length < offset+name->length)
1.3 markus 179: return GSS_S_FAILURE;
180:
1.2 markus 181: name->value = xmalloc(name->length+1);
1.1 markus 182: memcpy(name->value,tok+offset,name->length);
1.2 markus 183: ((char *)name->value)[name->length] = 0;
184:
1.1 markus 185: return GSS_S_COMPLETE;
1.3 markus 186: }
1.1 markus 187:
188: /* Extract the client details from a given context. This can only reliably
189: * be called once for a context */
190:
191: /* Priviledged (called from accept_secure_ctx) */
192: OM_uint32
193: ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
194: {
195: int i = 0;
196:
197: gss_buffer_desc ename;
1.3 markus 198:
1.1 markus 199: client->mech = NULL;
200:
201: while (supported_mechs[i]->name != NULL) {
202: if (supported_mechs[i]->oid.length == ctx->oid->length &&
203: (memcmp(supported_mechs[i]->oid.elements,
204: ctx->oid->elements, ctx->oid->length) == 0))
205: client->mech = supported_mechs[i];
206: i++;
207: }
208:
1.3 markus 209: if (client->mech == NULL)
1.1 markus 210: return GSS_S_FAILURE;
1.3 markus 211:
212: if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
1.1 markus 213: &client->displayname, NULL))) {
1.3 markus 214: ssh_gssapi_error(ctx);
215: return (ctx->major);
1.1 markus 216: }
1.3 markus 217:
218: if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
1.1 markus 219: &ename))) {
220: ssh_gssapi_error(ctx);
221: return (ctx->major);
222: }
1.3 markus 223:
1.1 markus 224: if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
225: &client->exportedname))) {
226: return (ctx->major);
227: }
228:
229: /* We can't copy this structure, so we just move the pointer to it */
230: client->creds = ctx->client_creds;
231: ctx->client_creds = GSS_C_NO_CREDENTIAL;
232: return (ctx->major);
233: }
234:
1.4 markus 235: /* As user - called on fatal/exit */
1.1 markus 236: void
1.4 markus 237: ssh_gssapi_cleanup_creds(void)
1.1 markus 238: {
239: if (gssapi_client.store.filename != NULL) {
240: /* Unlink probably isn't sufficient */
241: debug("removing gssapi cred file\"%s\"", gssapi_client.store.filename);
242: unlink(gssapi_client.store.filename);
243: }
244: }
245:
246: /* As user */
247: void
248: ssh_gssapi_storecreds(void)
249: {
250: if (gssapi_client.mech && gssapi_client.mech->storecreds) {
251: (*gssapi_client.mech->storecreds)(&gssapi_client);
252: } else
253: debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
254: }
255:
256: /* This allows GSSAPI methods to do things to the childs environment based
257: * on the passed authentication process and credentials.
258: */
259: /* As user */
260: void
261: ssh_gssapi_do_child(char ***envp, u_int *envsizep)
262: {
263:
264: if (gssapi_client.store.envvar != NULL &&
265: gssapi_client.store.envval != NULL) {
266:
267: debug("Setting %s to %s", gssapi_client.store.envvar,
268: gssapi_client.store.envval);
269: child_set_env(envp, envsizep, gssapi_client.store.envvar,
270: gssapi_client.store.envval);
271: }
272: }
273:
274: /* Priviledged */
275: int
276: ssh_gssapi_userok(char *user)
277: {
278: if (gssapi_client.exportedname.length == 0 ||
279: gssapi_client.exportedname.value == NULL) {
280: debug("No suitable client data");
281: return 0;
282: }
283: if (gssapi_client.mech && gssapi_client.mech->userok)
284: return ((*gssapi_client.mech->userok)(&gssapi_client, user));
285: else
286: debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
287: return (0);
1.5 ! markus 288: }
! 289:
! 290: /* Priviledged */
! 291: OM_uint32
! 292: ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
! 293: {
! 294: ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
! 295: gssbuf, gssmic, NULL);
! 296:
! 297: return (ctx->major);
1.1 markus 298: }
299:
300: #endif
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