Annotation of src/usr.bin/ssh/gss-serv.c, Revision 1.20
1.20 ! deraadt 1: /* $OpenBSD: gss-serv.c,v 1.19 2006/07/22 20:48:23 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:
1.20 ! deraadt 27: #include <sys/types.h>
1.1 markus 28:
29: #ifdef GSSAPI
1.19 stevesk 30:
31: #include <string.h>
1.1 markus 32:
1.20 ! deraadt 33: #include "xmalloc.h"
! 34: #include "buffer.h"
! 35: #include "key.h"
! 36: #include "hostfile.h"
1.1 markus 37: #include "auth.h"
38: #include "log.h"
39: #include "channels.h"
40: #include "session.h"
1.17 djm 41: #include "misc.h"
1.1 markus 42:
43: #include "ssh-gss.h"
44:
45: static ssh_gssapi_client gssapi_client =
46: { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
47: GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}};
48:
49: ssh_gssapi_mech gssapi_null_mech =
50: { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
51:
52: #ifdef KRB5
53: extern ssh_gssapi_mech gssapi_kerberos_mech;
54: #endif
55:
56: ssh_gssapi_mech* supported_mechs[]= {
57: #ifdef KRB5
58: &gssapi_kerberos_mech,
59: #endif
60: &gssapi_null_mech,
61: };
62:
1.11 stevesk 63: /* Unprivileged */
1.1 markus 64: void
65: ssh_gssapi_supported_oids(gss_OID_set *oidset)
66: {
67: int i = 0;
68: OM_uint32 min_status;
69: int present;
70: gss_OID_set supported;
71:
72: gss_create_empty_oid_set(&min_status, oidset);
73: gss_indicate_mechs(&min_status, &supported);
74:
75: while (supported_mechs[i]->name != NULL) {
76: if (GSS_ERROR(gss_test_oid_set_member(&min_status,
77: &supported_mechs[i]->oid, supported, &present)))
78: present = 0;
79: if (present)
80: gss_add_oid_set_member(&min_status,
81: &supported_mechs[i]->oid, oidset);
82: i++;
83: }
1.15 djm 84:
85: gss_release_oid_set(&min_status, &supported);
1.1 markus 86: }
87:
88:
89: /* Wrapper around accept_sec_context
90: * Requires that the context contains:
91: * oid
92: * credentials (from ssh_gssapi_acquire_cred)
93: */
1.11 stevesk 94: /* Privileged */
1.1 markus 95: OM_uint32
96: ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok,
97: gss_buffer_desc *send_tok, OM_uint32 *flags)
98: {
99: OM_uint32 status;
100: gss_OID mech;
101:
102: ctx->major = gss_accept_sec_context(&ctx->minor,
103: &ctx->context, ctx->creds, recv_tok,
104: GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
105: send_tok, flags, NULL, &ctx->client_creds);
106:
107: if (GSS_ERROR(ctx->major))
108: ssh_gssapi_error(ctx);
109:
110: if (ctx->client_creds)
111: debug("Received some client credentials");
112: else
113: debug("Got no client credentials");
114:
115: status = ctx->major;
116:
117: /* Now, if we're complete and we have the right flags, then
118: * we flag the user as also having been authenticated
119: */
120:
121: if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) &&
122: (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
123: if (ssh_gssapi_getclient(ctx, &gssapi_client))
124: fatal("Couldn't convert client name");
125: }
126:
127: return (status);
128: }
129:
130: /*
131: * This parses an exported name, extracting the mechanism specific portion
132: * to use for ACL checking. It verifies that the name belongs the mechanism
133: * originally selected.
134: */
135: static OM_uint32
136: ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
137: {
1.6 djm 138: u_char *tok;
1.1 markus 139: OM_uint32 offset;
140: OM_uint32 oidl;
1.3 markus 141:
1.13 stevesk 142: tok = ename->value;
1.3 markus 143:
144: /*
145: * Check that ename is long enough for all of the fixed length
1.1 markus 146: * header, and that the initial ID bytes are correct
147: */
148:
1.13 stevesk 149: if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0)
1.1 markus 150: return GSS_S_FAILURE;
151:
152: /*
153: * Extract the OID, and check it. Here GSSAPI breaks with tradition
154: * and does use the OID type and length bytes. To confuse things
155: * there are two lengths - the first including these, and the
156: * second without.
157: */
158:
1.17 djm 159: oidl = get_u16(tok+2); /* length including next two bytes */
1.1 markus 160: oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
161:
162: /*
163: * Check the BER encoding for correct type and length, that the
164: * string is long enough and that the OID matches that in our context
165: */
166: if (tok[4] != 0x06 || tok[5] != oidl ||
1.3 markus 167: ename->length < oidl+6 ||
1.13 stevesk 168: !ssh_gssapi_check_oid(ctx, tok+6, oidl))
1.1 markus 169: return GSS_S_FAILURE;
170:
171: offset = oidl+6;
1.3 markus 172:
1.1 markus 173: if (ename->length < offset+4)
174: return GSS_S_FAILURE;
1.3 markus 175:
1.17 djm 176: name->length = get_u32(tok+offset);
1.1 markus 177: offset += 4;
1.3 markus 178:
1.1 markus 179: if (ename->length < offset+name->length)
1.3 markus 180: return GSS_S_FAILURE;
181:
1.2 markus 182: name->value = xmalloc(name->length+1);
1.14 stevesk 183: memcpy(name->value, tok+offset, name->length);
1.2 markus 184: ((char *)name->value)[name->length] = 0;
185:
1.1 markus 186: return GSS_S_COMPLETE;
1.3 markus 187: }
1.1 markus 188:
189: /* Extract the client details from a given context. This can only reliably
190: * be called once for a context */
191:
1.11 stevesk 192: /* Privileged (called from accept_secure_ctx) */
1.1 markus 193: OM_uint32
194: ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
195: {
196: int i = 0;
197:
198: gss_buffer_desc ename;
1.3 markus 199:
1.1 markus 200: client->mech = NULL;
201:
202: while (supported_mechs[i]->name != NULL) {
203: if (supported_mechs[i]->oid.length == ctx->oid->length &&
204: (memcmp(supported_mechs[i]->oid.elements,
205: ctx->oid->elements, ctx->oid->length) == 0))
206: client->mech = supported_mechs[i];
207: i++;
208: }
209:
1.3 markus 210: if (client->mech == NULL)
1.1 markus 211: return GSS_S_FAILURE;
1.3 markus 212:
213: if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
1.1 markus 214: &client->displayname, NULL))) {
1.3 markus 215: ssh_gssapi_error(ctx);
216: return (ctx->major);
1.1 markus 217: }
1.3 markus 218:
219: if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
1.1 markus 220: &ename))) {
221: ssh_gssapi_error(ctx);
222: return (ctx->major);
223: }
1.3 markus 224:
1.1 markus 225: if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
226: &client->exportedname))) {
227: return (ctx->major);
228: }
229:
230: /* We can't copy this structure, so we just move the pointer to it */
231: client->creds = ctx->client_creds;
232: ctx->client_creds = GSS_C_NO_CREDENTIAL;
233: return (ctx->major);
234: }
235:
1.4 markus 236: /* As user - called on fatal/exit */
1.1 markus 237: void
1.4 markus 238: ssh_gssapi_cleanup_creds(void)
1.1 markus 239: {
240: if (gssapi_client.store.filename != NULL) {
241: /* Unlink probably isn't sufficient */
1.14 stevesk 242: debug("removing gssapi cred file\"%s\"",
243: gssapi_client.store.filename);
1.1 markus 244: unlink(gssapi_client.store.filename);
245: }
246: }
247:
248: /* As user */
249: void
250: ssh_gssapi_storecreds(void)
251: {
252: if (gssapi_client.mech && gssapi_client.mech->storecreds) {
253: (*gssapi_client.mech->storecreds)(&gssapi_client);
254: } else
255: debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
256: }
257:
258: /* This allows GSSAPI methods to do things to the childs environment based
259: * on the passed authentication process and credentials.
260: */
261: /* As user */
262: void
263: ssh_gssapi_do_child(char ***envp, u_int *envsizep)
264: {
265:
266: if (gssapi_client.store.envvar != NULL &&
267: gssapi_client.store.envval != NULL) {
268: debug("Setting %s to %s", gssapi_client.store.envvar,
1.13 stevesk 269: gssapi_client.store.envval);
1.1 markus 270: child_set_env(envp, envsizep, gssapi_client.store.envvar,
1.7 djm 271: gssapi_client.store.envval);
1.1 markus 272: }
273: }
274:
1.9 djm 275: /* Privileged */
1.1 markus 276: int
277: ssh_gssapi_userok(char *user)
278: {
1.8 djm 279: OM_uint32 lmin;
280:
1.1 markus 281: if (gssapi_client.exportedname.length == 0 ||
282: gssapi_client.exportedname.value == NULL) {
283: debug("No suitable client data");
284: return 0;
285: }
286: if (gssapi_client.mech && gssapi_client.mech->userok)
1.8 djm 287: if ((*gssapi_client.mech->userok)(&gssapi_client, user))
288: return 1;
289: else {
290: /* Destroy delegated credentials if userok fails */
291: gss_release_buffer(&lmin, &gssapi_client.displayname);
292: gss_release_buffer(&lmin, &gssapi_client.exportedname);
293: gss_release_cred(&lmin, &gssapi_client.creds);
294: memset(&gssapi_client, 0, sizeof(ssh_gssapi_client));
295: return 0;
296: }
1.1 markus 297: else
298: debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
299: return (0);
1.5 markus 300: }
301:
1.11 stevesk 302: /* Privileged */
1.5 markus 303: OM_uint32
304: ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
305: {
306: ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
307: gssbuf, gssmic, NULL);
308:
309: return (ctx->major);
1.1 markus 310: }
311:
312: #endif
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