Annotation of src/usr.bin/ssh/gss-serv.c, Revision 1.18
1.18 ! stevesk 1: /* $OpenBSD: gss-serv.c,v 1.17 2006/03/30 09:58:15 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:
27: #include "includes.h"
28:
29: #ifdef GSSAPI
30:
31: #include "bufaux.h"
32: #include "auth.h"
33: #include "log.h"
34: #include "channels.h"
35: #include "session.h"
36: #include "xmalloc.h"
1.17 djm 37: #include "misc.h"
1.1 markus 38:
39: #include "ssh-gss.h"
40:
41: static ssh_gssapi_client gssapi_client =
42: { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
43: GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}};
44:
45: ssh_gssapi_mech gssapi_null_mech =
46: { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
47:
48: #ifdef KRB5
49: extern ssh_gssapi_mech gssapi_kerberos_mech;
50: #endif
51:
52: ssh_gssapi_mech* supported_mechs[]= {
53: #ifdef KRB5
54: &gssapi_kerberos_mech,
55: #endif
56: &gssapi_null_mech,
57: };
58:
1.11 stevesk 59: /* Unprivileged */
1.1 markus 60: void
61: ssh_gssapi_supported_oids(gss_OID_set *oidset)
62: {
63: int i = 0;
64: OM_uint32 min_status;
65: int present;
66: gss_OID_set supported;
67:
68: gss_create_empty_oid_set(&min_status, oidset);
69: gss_indicate_mechs(&min_status, &supported);
70:
71: while (supported_mechs[i]->name != NULL) {
72: if (GSS_ERROR(gss_test_oid_set_member(&min_status,
73: &supported_mechs[i]->oid, supported, &present)))
74: present = 0;
75: if (present)
76: gss_add_oid_set_member(&min_status,
77: &supported_mechs[i]->oid, oidset);
78: i++;
79: }
1.15 djm 80:
81: gss_release_oid_set(&min_status, &supported);
1.1 markus 82: }
83:
84:
85: /* Wrapper around accept_sec_context
86: * Requires that the context contains:
87: * oid
88: * credentials (from ssh_gssapi_acquire_cred)
89: */
1.11 stevesk 90: /* Privileged */
1.1 markus 91: OM_uint32
92: ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok,
93: gss_buffer_desc *send_tok, OM_uint32 *flags)
94: {
95: OM_uint32 status;
96: gss_OID mech;
97:
98: ctx->major = gss_accept_sec_context(&ctx->minor,
99: &ctx->context, ctx->creds, recv_tok,
100: GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
101: send_tok, flags, NULL, &ctx->client_creds);
102:
103: if (GSS_ERROR(ctx->major))
104: ssh_gssapi_error(ctx);
105:
106: if (ctx->client_creds)
107: debug("Received some client credentials");
108: else
109: debug("Got no client credentials");
110:
111: status = ctx->major;
112:
113: /* Now, if we're complete and we have the right flags, then
114: * we flag the user as also having been authenticated
115: */
116:
117: if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) &&
118: (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
119: if (ssh_gssapi_getclient(ctx, &gssapi_client))
120: fatal("Couldn't convert client name");
121: }
122:
123: return (status);
124: }
125:
126: /*
127: * This parses an exported name, extracting the mechanism specific portion
128: * to use for ACL checking. It verifies that the name belongs the mechanism
129: * originally selected.
130: */
131: static OM_uint32
132: ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
133: {
1.6 djm 134: u_char *tok;
1.1 markus 135: OM_uint32 offset;
136: OM_uint32 oidl;
1.3 markus 137:
1.13 stevesk 138: tok = ename->value;
1.3 markus 139:
140: /*
141: * Check that ename is long enough for all of the fixed length
1.1 markus 142: * header, and that the initial ID bytes are correct
143: */
144:
1.13 stevesk 145: if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0)
1.1 markus 146: return GSS_S_FAILURE;
147:
148: /*
149: * Extract the OID, and check it. Here GSSAPI breaks with tradition
150: * and does use the OID type and length bytes. To confuse things
151: * there are two lengths - the first including these, and the
152: * second without.
153: */
154:
1.17 djm 155: oidl = get_u16(tok+2); /* length including next two bytes */
1.1 markus 156: oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
157:
158: /*
159: * Check the BER encoding for correct type and length, that the
160: * string is long enough and that the OID matches that in our context
161: */
162: if (tok[4] != 0x06 || tok[5] != oidl ||
1.3 markus 163: ename->length < oidl+6 ||
1.13 stevesk 164: !ssh_gssapi_check_oid(ctx, tok+6, oidl))
1.1 markus 165: return GSS_S_FAILURE;
166:
167: offset = oidl+6;
1.3 markus 168:
1.1 markus 169: if (ename->length < offset+4)
170: return GSS_S_FAILURE;
1.3 markus 171:
1.17 djm 172: name->length = get_u32(tok+offset);
1.1 markus 173: offset += 4;
1.3 markus 174:
1.1 markus 175: if (ename->length < offset+name->length)
1.3 markus 176: return GSS_S_FAILURE;
177:
1.2 markus 178: name->value = xmalloc(name->length+1);
1.14 stevesk 179: memcpy(name->value, tok+offset, name->length);
1.2 markus 180: ((char *)name->value)[name->length] = 0;
181:
1.1 markus 182: return GSS_S_COMPLETE;
1.3 markus 183: }
1.1 markus 184:
185: /* Extract the client details from a given context. This can only reliably
186: * be called once for a context */
187:
1.11 stevesk 188: /* Privileged (called from accept_secure_ctx) */
1.1 markus 189: OM_uint32
190: ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
191: {
192: int i = 0;
193:
194: gss_buffer_desc ename;
1.3 markus 195:
1.1 markus 196: client->mech = NULL;
197:
198: while (supported_mechs[i]->name != NULL) {
199: if (supported_mechs[i]->oid.length == ctx->oid->length &&
200: (memcmp(supported_mechs[i]->oid.elements,
201: ctx->oid->elements, ctx->oid->length) == 0))
202: client->mech = supported_mechs[i];
203: i++;
204: }
205:
1.3 markus 206: if (client->mech == NULL)
1.1 markus 207: return GSS_S_FAILURE;
1.3 markus 208:
209: if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
1.1 markus 210: &client->displayname, NULL))) {
1.3 markus 211: ssh_gssapi_error(ctx);
212: return (ctx->major);
1.1 markus 213: }
1.3 markus 214:
215: if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
1.1 markus 216: &ename))) {
217: ssh_gssapi_error(ctx);
218: return (ctx->major);
219: }
1.3 markus 220:
1.1 markus 221: if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
222: &client->exportedname))) {
223: return (ctx->major);
224: }
225:
226: /* We can't copy this structure, so we just move the pointer to it */
227: client->creds = ctx->client_creds;
228: ctx->client_creds = GSS_C_NO_CREDENTIAL;
229: return (ctx->major);
230: }
231:
1.4 markus 232: /* As user - called on fatal/exit */
1.1 markus 233: void
1.4 markus 234: ssh_gssapi_cleanup_creds(void)
1.1 markus 235: {
236: if (gssapi_client.store.filename != NULL) {
237: /* Unlink probably isn't sufficient */
1.14 stevesk 238: debug("removing gssapi cred file\"%s\"",
239: gssapi_client.store.filename);
1.1 markus 240: unlink(gssapi_client.store.filename);
241: }
242: }
243:
244: /* As user */
245: void
246: ssh_gssapi_storecreds(void)
247: {
248: if (gssapi_client.mech && gssapi_client.mech->storecreds) {
249: (*gssapi_client.mech->storecreds)(&gssapi_client);
250: } else
251: debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
252: }
253:
254: /* This allows GSSAPI methods to do things to the childs environment based
255: * on the passed authentication process and credentials.
256: */
257: /* As user */
258: void
259: ssh_gssapi_do_child(char ***envp, u_int *envsizep)
260: {
261:
262: if (gssapi_client.store.envvar != NULL &&
263: gssapi_client.store.envval != NULL) {
264: debug("Setting %s to %s", gssapi_client.store.envvar,
1.13 stevesk 265: gssapi_client.store.envval);
1.1 markus 266: child_set_env(envp, envsizep, gssapi_client.store.envvar,
1.7 djm 267: gssapi_client.store.envval);
1.1 markus 268: }
269: }
270:
1.9 djm 271: /* Privileged */
1.1 markus 272: int
273: ssh_gssapi_userok(char *user)
274: {
1.8 djm 275: OM_uint32 lmin;
276:
1.1 markus 277: if (gssapi_client.exportedname.length == 0 ||
278: gssapi_client.exportedname.value == NULL) {
279: debug("No suitable client data");
280: return 0;
281: }
282: if (gssapi_client.mech && gssapi_client.mech->userok)
1.8 djm 283: if ((*gssapi_client.mech->userok)(&gssapi_client, user))
284: return 1;
285: else {
286: /* Destroy delegated credentials if userok fails */
287: gss_release_buffer(&lmin, &gssapi_client.displayname);
288: gss_release_buffer(&lmin, &gssapi_client.exportedname);
289: gss_release_cred(&lmin, &gssapi_client.creds);
290: memset(&gssapi_client, 0, sizeof(ssh_gssapi_client));
291: return 0;
292: }
1.1 markus 293: else
294: debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
295: return (0);
1.5 markus 296: }
297:
1.11 stevesk 298: /* Privileged */
1.5 markus 299: OM_uint32
300: ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
301: {
302: ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
303: gssbuf, gssmic, NULL);
304:
305: return (ctx->major);
1.1 markus 306: }
307:
308: #endif
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