Annotation of src/usr.bin/ssh/gss-serv.c, Revision 1.19
1.19 ! stevesk 1: /* $OpenBSD: gss-serv.c,v 1.18 2006/07/02 18:36:47 stevesk 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
1.19 ! stevesk 30:
! 31: #include <string.h>
1.1 markus 32:
33: #include "bufaux.h"
34: #include "auth.h"
35: #include "log.h"
36: #include "channels.h"
37: #include "session.h"
38: #include "xmalloc.h"
1.17 djm 39: #include "misc.h"
1.1 markus 40:
41: #include "ssh-gss.h"
42:
43: static ssh_gssapi_client gssapi_client =
44: { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
45: GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}};
46:
47: ssh_gssapi_mech gssapi_null_mech =
48: { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
49:
50: #ifdef KRB5
51: extern ssh_gssapi_mech gssapi_kerberos_mech;
52: #endif
53:
54: ssh_gssapi_mech* supported_mechs[]= {
55: #ifdef KRB5
56: &gssapi_kerberos_mech,
57: #endif
58: &gssapi_null_mech,
59: };
60:
1.11 stevesk 61: /* Unprivileged */
1.1 markus 62: void
63: ssh_gssapi_supported_oids(gss_OID_set *oidset)
64: {
65: int i = 0;
66: OM_uint32 min_status;
67: int present;
68: gss_OID_set supported;
69:
70: gss_create_empty_oid_set(&min_status, oidset);
71: gss_indicate_mechs(&min_status, &supported);
72:
73: while (supported_mechs[i]->name != NULL) {
74: if (GSS_ERROR(gss_test_oid_set_member(&min_status,
75: &supported_mechs[i]->oid, supported, &present)))
76: present = 0;
77: if (present)
78: gss_add_oid_set_member(&min_status,
79: &supported_mechs[i]->oid, oidset);
80: i++;
81: }
1.15 djm 82:
83: gss_release_oid_set(&min_status, &supported);
1.1 markus 84: }
85:
86:
87: /* Wrapper around accept_sec_context
88: * Requires that the context contains:
89: * oid
90: * credentials (from ssh_gssapi_acquire_cred)
91: */
1.11 stevesk 92: /* Privileged */
1.1 markus 93: OM_uint32
94: ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok,
95: gss_buffer_desc *send_tok, OM_uint32 *flags)
96: {
97: OM_uint32 status;
98: gss_OID mech;
99:
100: ctx->major = gss_accept_sec_context(&ctx->minor,
101: &ctx->context, ctx->creds, recv_tok,
102: GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
103: send_tok, flags, NULL, &ctx->client_creds);
104:
105: if (GSS_ERROR(ctx->major))
106: ssh_gssapi_error(ctx);
107:
108: if (ctx->client_creds)
109: debug("Received some client credentials");
110: else
111: debug("Got no client credentials");
112:
113: status = ctx->major;
114:
115: /* Now, if we're complete and we have the right flags, then
116: * we flag the user as also having been authenticated
117: */
118:
119: if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) &&
120: (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
121: if (ssh_gssapi_getclient(ctx, &gssapi_client))
122: fatal("Couldn't convert client name");
123: }
124:
125: return (status);
126: }
127:
128: /*
129: * This parses an exported name, extracting the mechanism specific portion
130: * to use for ACL checking. It verifies that the name belongs the mechanism
131: * originally selected.
132: */
133: static OM_uint32
134: ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
135: {
1.6 djm 136: u_char *tok;
1.1 markus 137: OM_uint32 offset;
138: OM_uint32 oidl;
1.3 markus 139:
1.13 stevesk 140: tok = ename->value;
1.3 markus 141:
142: /*
143: * Check that ename is long enough for all of the fixed length
1.1 markus 144: * header, and that the initial ID bytes are correct
145: */
146:
1.13 stevesk 147: if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0)
1.1 markus 148: return GSS_S_FAILURE;
149:
150: /*
151: * Extract the OID, and check it. Here GSSAPI breaks with tradition
152: * and does use the OID type and length bytes. To confuse things
153: * there are two lengths - the first including these, and the
154: * second without.
155: */
156:
1.17 djm 157: oidl = get_u16(tok+2); /* length including next two bytes */
1.1 markus 158: oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
159:
160: /*
161: * Check the BER encoding for correct type and length, that the
162: * string is long enough and that the OID matches that in our context
163: */
164: if (tok[4] != 0x06 || tok[5] != oidl ||
1.3 markus 165: ename->length < oidl+6 ||
1.13 stevesk 166: !ssh_gssapi_check_oid(ctx, tok+6, oidl))
1.1 markus 167: return GSS_S_FAILURE;
168:
169: offset = oidl+6;
1.3 markus 170:
1.1 markus 171: if (ename->length < offset+4)
172: return GSS_S_FAILURE;
1.3 markus 173:
1.17 djm 174: name->length = get_u32(tok+offset);
1.1 markus 175: offset += 4;
1.3 markus 176:
1.1 markus 177: if (ename->length < offset+name->length)
1.3 markus 178: return GSS_S_FAILURE;
179:
1.2 markus 180: name->value = xmalloc(name->length+1);
1.14 stevesk 181: memcpy(name->value, tok+offset, name->length);
1.2 markus 182: ((char *)name->value)[name->length] = 0;
183:
1.1 markus 184: return GSS_S_COMPLETE;
1.3 markus 185: }
1.1 markus 186:
187: /* Extract the client details from a given context. This can only reliably
188: * be called once for a context */
189:
1.11 stevesk 190: /* Privileged (called from accept_secure_ctx) */
1.1 markus 191: OM_uint32
192: ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
193: {
194: int i = 0;
195:
196: gss_buffer_desc ename;
1.3 markus 197:
1.1 markus 198: client->mech = NULL;
199:
200: while (supported_mechs[i]->name != NULL) {
201: if (supported_mechs[i]->oid.length == ctx->oid->length &&
202: (memcmp(supported_mechs[i]->oid.elements,
203: ctx->oid->elements, ctx->oid->length) == 0))
204: client->mech = supported_mechs[i];
205: i++;
206: }
207:
1.3 markus 208: if (client->mech == NULL)
1.1 markus 209: return GSS_S_FAILURE;
1.3 markus 210:
211: if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
1.1 markus 212: &client->displayname, NULL))) {
1.3 markus 213: ssh_gssapi_error(ctx);
214: return (ctx->major);
1.1 markus 215: }
1.3 markus 216:
217: if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
1.1 markus 218: &ename))) {
219: ssh_gssapi_error(ctx);
220: return (ctx->major);
221: }
1.3 markus 222:
1.1 markus 223: if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
224: &client->exportedname))) {
225: return (ctx->major);
226: }
227:
228: /* We can't copy this structure, so we just move the pointer to it */
229: client->creds = ctx->client_creds;
230: ctx->client_creds = GSS_C_NO_CREDENTIAL;
231: return (ctx->major);
232: }
233:
1.4 markus 234: /* As user - called on fatal/exit */
1.1 markus 235: void
1.4 markus 236: ssh_gssapi_cleanup_creds(void)
1.1 markus 237: {
238: if (gssapi_client.store.filename != NULL) {
239: /* Unlink probably isn't sufficient */
1.14 stevesk 240: debug("removing gssapi cred file\"%s\"",
241: gssapi_client.store.filename);
1.1 markus 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: debug("Setting %s to %s", gssapi_client.store.envvar,
1.13 stevesk 267: gssapi_client.store.envval);
1.1 markus 268: child_set_env(envp, envsizep, gssapi_client.store.envvar,
1.7 djm 269: gssapi_client.store.envval);
1.1 markus 270: }
271: }
272:
1.9 djm 273: /* Privileged */
1.1 markus 274: int
275: ssh_gssapi_userok(char *user)
276: {
1.8 djm 277: OM_uint32 lmin;
278:
1.1 markus 279: if (gssapi_client.exportedname.length == 0 ||
280: gssapi_client.exportedname.value == NULL) {
281: debug("No suitable client data");
282: return 0;
283: }
284: if (gssapi_client.mech && gssapi_client.mech->userok)
1.8 djm 285: if ((*gssapi_client.mech->userok)(&gssapi_client, user))
286: return 1;
287: else {
288: /* Destroy delegated credentials if userok fails */
289: gss_release_buffer(&lmin, &gssapi_client.displayname);
290: gss_release_buffer(&lmin, &gssapi_client.exportedname);
291: gss_release_cred(&lmin, &gssapi_client.creds);
292: memset(&gssapi_client, 0, sizeof(ssh_gssapi_client));
293: return 0;
294: }
1.1 markus 295: else
296: debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
297: return (0);
1.5 markus 298: }
299:
1.11 stevesk 300: /* Privileged */
1.5 markus 301: OM_uint32
302: ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
303: {
304: ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
305: gssbuf, gssmic, NULL);
306:
307: return (ctx->major);
1.1 markus 308: }
309:
310: #endif
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