Annotation of src/usr.bin/ssh/gss-serv.c, Revision 1.14
1.14 ! stevesk 1: /* $OpenBSD: gss-serv.c,v 1.13 2005/10/13 22:24:31 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
30:
31: #include "bufaux.h"
32: #include "auth.h"
33: #include "log.h"
34: #include "channels.h"
35: #include "session.h"
36: #include "servconf.h"
37: #include "xmalloc.h"
38: #include "getput.h"
39:
40: #include "ssh-gss.h"
41:
42: static ssh_gssapi_client gssapi_client =
43: { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
44: GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}};
45:
46: ssh_gssapi_mech gssapi_null_mech =
47: { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
48:
49: #ifdef KRB5
50: extern ssh_gssapi_mech gssapi_kerberos_mech;
51: #endif
52:
53: ssh_gssapi_mech* supported_mechs[]= {
54: #ifdef KRB5
55: &gssapi_kerberos_mech,
56: #endif
57: &gssapi_null_mech,
58: };
59:
1.11 stevesk 60: /* Unprivileged */
1.1 markus 61: void
62: ssh_gssapi_supported_oids(gss_OID_set *oidset)
63: {
64: int i = 0;
65: OM_uint32 min_status;
66: int present;
67: gss_OID_set supported;
68:
69: gss_create_empty_oid_set(&min_status, oidset);
70: gss_indicate_mechs(&min_status, &supported);
71:
72: while (supported_mechs[i]->name != NULL) {
73: if (GSS_ERROR(gss_test_oid_set_member(&min_status,
74: &supported_mechs[i]->oid, supported, &present)))
75: present = 0;
76: if (present)
77: gss_add_oid_set_member(&min_status,
78: &supported_mechs[i]->oid, oidset);
79: i++;
80: }
81: }
82:
83:
84: /* Wrapper around accept_sec_context
85: * Requires that the context contains:
86: * oid
87: * credentials (from ssh_gssapi_acquire_cred)
88: */
1.11 stevesk 89: /* Privileged */
1.1 markus 90: OM_uint32
91: ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok,
92: gss_buffer_desc *send_tok, OM_uint32 *flags)
93: {
94: OM_uint32 status;
95: gss_OID mech;
96:
97: ctx->major = gss_accept_sec_context(&ctx->minor,
98: &ctx->context, ctx->creds, recv_tok,
99: GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
100: send_tok, flags, NULL, &ctx->client_creds);
101:
102: if (GSS_ERROR(ctx->major))
103: ssh_gssapi_error(ctx);
104:
105: if (ctx->client_creds)
106: debug("Received some client credentials");
107: else
108: debug("Got no client credentials");
109:
110: status = ctx->major;
111:
112: /* Now, if we're complete and we have the right flags, then
113: * we flag the user as also having been authenticated
114: */
115:
116: if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) &&
117: (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
118: if (ssh_gssapi_getclient(ctx, &gssapi_client))
119: fatal("Couldn't convert client name");
120: }
121:
122: return (status);
123: }
124:
125: /*
126: * This parses an exported name, extracting the mechanism specific portion
127: * to use for ACL checking. It verifies that the name belongs the mechanism
128: * originally selected.
129: */
130: static OM_uint32
131: ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
132: {
1.6 djm 133: u_char *tok;
1.1 markus 134: OM_uint32 offset;
135: OM_uint32 oidl;
1.3 markus 136:
1.13 stevesk 137: tok = ename->value;
1.3 markus 138:
139: /*
140: * Check that ename is long enough for all of the fixed length
1.1 markus 141: * header, and that the initial ID bytes are correct
142: */
143:
1.13 stevesk 144: if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0)
1.1 markus 145: return GSS_S_FAILURE;
146:
147: /*
148: * Extract the OID, and check it. Here GSSAPI breaks with tradition
149: * and does use the OID type and length bytes. To confuse things
150: * there are two lengths - the first including these, and the
151: * second without.
152: */
153:
154: oidl = GET_16BIT(tok+2); /* length including next two bytes */
155: oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
156:
157: /*
158: * Check the BER encoding for correct type and length, that the
159: * string is long enough and that the OID matches that in our context
160: */
161: if (tok[4] != 0x06 || tok[5] != oidl ||
1.3 markus 162: ename->length < oidl+6 ||
1.13 stevesk 163: !ssh_gssapi_check_oid(ctx, tok+6, oidl))
1.1 markus 164: return GSS_S_FAILURE;
165:
166: offset = oidl+6;
1.3 markus 167:
1.1 markus 168: if (ename->length < offset+4)
169: return GSS_S_FAILURE;
1.3 markus 170:
1.1 markus 171: name->length = GET_32BIT(tok+offset);
172: offset += 4;
1.3 markus 173:
1.1 markus 174: if (ename->length < offset+name->length)
1.3 markus 175: return GSS_S_FAILURE;
176:
1.2 markus 177: name->value = xmalloc(name->length+1);
1.14 ! stevesk 178: memcpy(name->value, tok+offset, name->length);
1.2 markus 179: ((char *)name->value)[name->length] = 0;
180:
1.1 markus 181: return GSS_S_COMPLETE;
1.3 markus 182: }
1.1 markus 183:
184: /* Extract the client details from a given context. This can only reliably
185: * be called once for a context */
186:
1.11 stevesk 187: /* Privileged (called from accept_secure_ctx) */
1.1 markus 188: OM_uint32
189: ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
190: {
191: int i = 0;
192:
193: gss_buffer_desc ename;
1.3 markus 194:
1.1 markus 195: client->mech = NULL;
196:
197: while (supported_mechs[i]->name != NULL) {
198: if (supported_mechs[i]->oid.length == ctx->oid->length &&
199: (memcmp(supported_mechs[i]->oid.elements,
200: ctx->oid->elements, ctx->oid->length) == 0))
201: client->mech = supported_mechs[i];
202: i++;
203: }
204:
1.3 markus 205: if (client->mech == NULL)
1.1 markus 206: return GSS_S_FAILURE;
1.3 markus 207:
208: if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
1.1 markus 209: &client->displayname, NULL))) {
1.3 markus 210: ssh_gssapi_error(ctx);
211: return (ctx->major);
1.1 markus 212: }
1.3 markus 213:
214: if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
1.1 markus 215: &ename))) {
216: ssh_gssapi_error(ctx);
217: return (ctx->major);
218: }
1.3 markus 219:
1.1 markus 220: if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
221: &client->exportedname))) {
222: return (ctx->major);
223: }
224:
225: /* We can't copy this structure, so we just move the pointer to it */
226: client->creds = ctx->client_creds;
227: ctx->client_creds = GSS_C_NO_CREDENTIAL;
228: return (ctx->major);
229: }
230:
1.4 markus 231: /* As user - called on fatal/exit */
1.1 markus 232: void
1.4 markus 233: ssh_gssapi_cleanup_creds(void)
1.1 markus 234: {
235: if (gssapi_client.store.filename != NULL) {
236: /* Unlink probably isn't sufficient */
1.14 ! stevesk 237: debug("removing gssapi cred file\"%s\"",
! 238: gssapi_client.store.filename);
1.1 markus 239: unlink(gssapi_client.store.filename);
240: }
241: }
242:
243: /* As user */
244: void
245: ssh_gssapi_storecreds(void)
246: {
247: if (gssapi_client.mech && gssapi_client.mech->storecreds) {
248: (*gssapi_client.mech->storecreds)(&gssapi_client);
249: } else
250: debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
251: }
252:
253: /* This allows GSSAPI methods to do things to the childs environment based
254: * on the passed authentication process and credentials.
255: */
256: /* As user */
257: void
258: ssh_gssapi_do_child(char ***envp, u_int *envsizep)
259: {
260:
261: if (gssapi_client.store.envvar != NULL &&
262: gssapi_client.store.envval != NULL) {
263: debug("Setting %s to %s", gssapi_client.store.envvar,
1.13 stevesk 264: gssapi_client.store.envval);
1.1 markus 265: child_set_env(envp, envsizep, gssapi_client.store.envvar,
1.7 djm 266: gssapi_client.store.envval);
1.1 markus 267: }
268: }
269:
1.9 djm 270: /* Privileged */
1.1 markus 271: int
272: ssh_gssapi_userok(char *user)
273: {
1.8 djm 274: OM_uint32 lmin;
275:
1.1 markus 276: if (gssapi_client.exportedname.length == 0 ||
277: gssapi_client.exportedname.value == NULL) {
278: debug("No suitable client data");
279: return 0;
280: }
281: if (gssapi_client.mech && gssapi_client.mech->userok)
1.8 djm 282: if ((*gssapi_client.mech->userok)(&gssapi_client, user))
283: return 1;
284: else {
285: /* Destroy delegated credentials if userok fails */
286: gss_release_buffer(&lmin, &gssapi_client.displayname);
287: gss_release_buffer(&lmin, &gssapi_client.exportedname);
288: gss_release_cred(&lmin, &gssapi_client.creds);
289: memset(&gssapi_client, 0, sizeof(ssh_gssapi_client));
290: return 0;
291: }
1.1 markus 292: else
293: debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
294: return (0);
1.5 markus 295: }
296:
1.11 stevesk 297: /* Privileged */
1.5 markus 298: OM_uint32
299: ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
300: {
301: ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
302: gssbuf, gssmic, NULL);
303:
304: return (ctx->major);
1.1 markus 305: }
306:
307: #endif
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