Annotation of src/usr.bin/ssh/gss-genr.c, Revision 1.29
1.29 ! djm 1: /* $OpenBSD: gss-genr.c,v 1.28 2021/01/27 10:05:28 djm Exp $ */
1.1 markus 2:
3: /*
1.19 dtucker 4: * Copyright (c) 2001-2007 Simon Wilkinson. All rights reserved.
1.1 markus 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: #ifdef GSSAPI
1.12 stevesk 28:
1.11 stevesk 29:
1.20 dtucker 30: #include <stdarg.h>
1.11 stevesk 31: #include <string.h>
1.23 deraadt 32: #include <limits.h>
1.1 markus 33:
34: #include "xmalloc.h"
1.25 markus 35: #include "ssherr.h"
36: #include "sshbuf.h"
1.1 markus 37: #include "log.h"
1.2 markus 38: #include "ssh2.h"
1.1 markus 39:
40: #include "ssh-gss.h"
41:
1.26 djm 42: /* sshbuf_get for gss_buffer_desc */
43: int
44: ssh_gssapi_get_buffer_desc(struct sshbuf *b, gss_buffer_desc *g)
45: {
46: int r;
47: u_char *p;
48: size_t len;
49:
50: if ((r = sshbuf_get_string(b, &p, &len)) != 0)
51: return r;
52: g->value = p;
53: g->length = len;
54: return 0;
55: }
1.1 markus 56:
57: /* Check that the OID in a data stream matches that in the context */
58: int
59: ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len)
60: {
61: return (ctx != NULL && ctx->oid != GSS_C_NO_OID &&
62: ctx->oid->length == len &&
63: memcmp(ctx->oid->elements, data, len) == 0);
64: }
65:
66: /* Set the contexts OID from a data stream */
67: void
68: ssh_gssapi_set_oid_data(Gssctxt *ctx, void *data, size_t len)
69: {
70: if (ctx->oid != GSS_C_NO_OID) {
1.21 djm 71: free(ctx->oid->elements);
72: free(ctx->oid);
1.1 markus 73: }
1.22 djm 74: ctx->oid = xcalloc(1, sizeof(gss_OID_desc));
1.1 markus 75: ctx->oid->length = len;
76: ctx->oid->elements = xmalloc(len);
77: memcpy(ctx->oid->elements, data, len);
78: }
79:
80: /* Set the contexts OID */
81: void
82: ssh_gssapi_set_oid(Gssctxt *ctx, gss_OID oid)
83: {
84: ssh_gssapi_set_oid_data(ctx, oid->elements, oid->length);
85: }
86:
87: /* All this effort to report an error ... */
88: void
89: ssh_gssapi_error(Gssctxt *ctxt)
90: {
1.7 djm 91: char *s;
92:
93: s = ssh_gssapi_last_error(ctxt, NULL, NULL);
94: debug("%s", s);
1.21 djm 95: free(s);
1.1 markus 96: }
97:
98: char *
1.4 djm 99: ssh_gssapi_last_error(Gssctxt *ctxt, OM_uint32 *major_status,
100: OM_uint32 *minor_status)
1.1 markus 101: {
102: OM_uint32 lmin;
103: gss_buffer_desc msg = GSS_C_EMPTY_BUFFER;
104: OM_uint32 ctx;
1.25 markus 105: struct sshbuf *b;
1.1 markus 106: char *ret;
1.25 markus 107: int r;
1.1 markus 108:
1.25 markus 109: if ((b = sshbuf_new()) == NULL)
1.27 djm 110: fatal_f("sshbuf_new failed");
1.1 markus 111:
112: if (major_status != NULL)
113: *major_status = ctxt->major;
114: if (minor_status != NULL)
115: *minor_status = ctxt->minor;
116:
117: ctx = 0;
118: /* The GSSAPI error */
119: do {
120: gss_display_status(&lmin, ctxt->major,
1.19 dtucker 121: GSS_C_GSS_CODE, ctxt->oid, &ctx, &msg);
1.1 markus 122:
1.25 markus 123: if ((r = sshbuf_put(b, msg.value, msg.length)) != 0 ||
124: (r = sshbuf_put_u8(b, '\n')) != 0)
1.27 djm 125: fatal_fr(r, "assemble GSS_CODE");
1.1 markus 126:
127: gss_release_buffer(&lmin, &msg);
128: } while (ctx != 0);
129:
130: /* The mechanism specific error */
131: do {
132: gss_display_status(&lmin, ctxt->minor,
1.19 dtucker 133: GSS_C_MECH_CODE, ctxt->oid, &ctx, &msg);
1.1 markus 134:
1.25 markus 135: if ((r = sshbuf_put(b, msg.value, msg.length)) != 0 ||
136: (r = sshbuf_put_u8(b, '\n')) != 0)
1.27 djm 137: fatal_fr(r, "assemble MECH_CODE");
1.1 markus 138:
139: gss_release_buffer(&lmin, &msg);
140: } while (ctx != 0);
141:
1.25 markus 142: if ((r = sshbuf_put_u8(b, '\n')) != 0)
1.27 djm 143: fatal_fr(r, "assemble newline");
1.25 markus 144: ret = xstrdup((const char *)sshbuf_ptr(b));
145: sshbuf_free(b);
1.1 markus 146: return (ret);
147: }
148:
149: /*
150: * Initialise our GSSAPI context. We use this opaque structure to contain all
151: * of the data which both the client and server need to persist across
152: * {accept,init}_sec_context calls, so that when we do it from the userauth
153: * stuff life is a little easier
154: */
155: void
156: ssh_gssapi_build_ctx(Gssctxt **ctx)
157: {
1.8 djm 158: *ctx = xcalloc(1, sizeof (Gssctxt));
1.1 markus 159: (*ctx)->context = GSS_C_NO_CONTEXT;
160: (*ctx)->name = GSS_C_NO_NAME;
161: (*ctx)->oid = GSS_C_NO_OID;
162: (*ctx)->creds = GSS_C_NO_CREDENTIAL;
163: (*ctx)->client = GSS_C_NO_NAME;
164: (*ctx)->client_creds = GSS_C_NO_CREDENTIAL;
165: }
166:
167: /* Delete our context, providing it has been built correctly */
168: void
169: ssh_gssapi_delete_ctx(Gssctxt **ctx)
170: {
171: OM_uint32 ms;
172:
173: if ((*ctx) == NULL)
174: return;
175: if ((*ctx)->context != GSS_C_NO_CONTEXT)
176: gss_delete_sec_context(&ms, &(*ctx)->context, GSS_C_NO_BUFFER);
177: if ((*ctx)->name != GSS_C_NO_NAME)
178: gss_release_name(&ms, &(*ctx)->name);
179: if ((*ctx)->oid != GSS_C_NO_OID) {
1.21 djm 180: free((*ctx)->oid->elements);
181: free((*ctx)->oid);
1.1 markus 182: (*ctx)->oid = GSS_C_NO_OID;
183: }
184: if ((*ctx)->creds != GSS_C_NO_CREDENTIAL)
185: gss_release_cred(&ms, &(*ctx)->creds);
186: if ((*ctx)->client != GSS_C_NO_NAME)
187: gss_release_name(&ms, &(*ctx)->client);
188: if ((*ctx)->client_creds != GSS_C_NO_CREDENTIAL)
189: gss_release_cred(&ms, &(*ctx)->client_creds);
190:
1.21 djm 191: free(*ctx);
1.1 markus 192: *ctx = NULL;
193: }
194:
195: /*
196: * Wrapper to init_sec_context
197: * Requires that the context contains:
198: * oid
199: * server name (from ssh_gssapi_import_name)
200: */
201: OM_uint32
202: ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok,
203: gss_buffer_desc* send_tok, OM_uint32 *flags)
204: {
205: int deleg_flag = 0;
206:
207: if (deleg_creds) {
208: deleg_flag = GSS_C_DELEG_FLAG;
209: debug("Delegating credentials");
210: }
211:
212: ctx->major = gss_init_sec_context(&ctx->minor,
213: GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid,
214: GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag,
215: 0, NULL, recv_tok, NULL, send_tok, flags, NULL);
216:
217: if (GSS_ERROR(ctx->major))
218: ssh_gssapi_error(ctx);
219:
220: return (ctx->major);
221: }
222:
223: /* Create a service name for the given host */
224: OM_uint32
225: ssh_gssapi_import_name(Gssctxt *ctx, const char *host)
226: {
227: gss_buffer_desc gssbuf;
1.10 djm 228: char *val;
1.1 markus 229:
1.10 djm 230: xasprintf(&val, "host@%s", host);
231: gssbuf.value = val;
232: gssbuf.length = strlen(gssbuf.value);
1.1 markus 233:
234: if ((ctx->major = gss_import_name(&ctx->minor,
235: &gssbuf, GSS_C_NT_HOSTBASED_SERVICE, &ctx->name)))
236: ssh_gssapi_error(ctx);
237:
1.21 djm 238: free(gssbuf.value);
1.1 markus 239: return (ctx->major);
240: }
241:
1.2 markus 242: OM_uint32
243: ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash)
244: {
245: if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context,
246: GSS_C_QOP_DEFAULT, buffer, hash)))
247: ssh_gssapi_error(ctx);
1.3 djm 248:
1.2 markus 249: return (ctx->major);
250: }
251:
252: void
1.25 markus 253: ssh_gssapi_buildmic(struct sshbuf *b, const char *user, const char *service,
1.28 djm 254: const char *context, const struct sshbuf *session_id)
1.3 djm 255: {
1.25 markus 256: int r;
257:
258: sshbuf_reset(b);
1.28 djm 259: if ((r = sshbuf_put_stringb(b, session_id)) != 0 ||
1.25 markus 260: (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
261: (r = sshbuf_put_cstring(b, user)) != 0 ||
262: (r = sshbuf_put_cstring(b, service)) != 0 ||
263: (r = sshbuf_put_cstring(b, context)) != 0)
1.27 djm 264: fatal_fr(r, "assemble buildmic");
1.14 djm 265: }
266:
267: int
1.15 djm 268: ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host)
1.14 djm 269: {
270: gss_buffer_desc token = GSS_C_EMPTY_BUFFER;
271: OM_uint32 major, minor;
272: gss_OID_desc spnego_oid = {6, (void *)"\x2B\x06\x01\x05\x05\x02"};
273:
274: /* RFC 4462 says we MUST NOT do SPNEGO */
1.29 ! djm 275: if (oid->length == spnego_oid.length &&
1.14 djm 276: (memcmp(oid->elements, spnego_oid.elements, oid->length) == 0))
1.16 djm 277: return 0; /* false */
1.14 djm 278:
279: ssh_gssapi_build_ctx(ctx);
280: ssh_gssapi_set_oid(*ctx, oid);
281: major = ssh_gssapi_import_name(*ctx, host);
282: if (!GSS_ERROR(major)) {
1.29 ! djm 283: major = ssh_gssapi_init_ctx(*ctx, 0, GSS_C_NO_BUFFER, &token,
1.14 djm 284: NULL);
285: gss_release_buffer(&minor, &token);
1.17 dtucker 286: if ((*ctx)->context != GSS_C_NO_CONTEXT)
287: gss_delete_sec_context(&minor, &(*ctx)->context,
288: GSS_C_NO_BUFFER);
1.14 djm 289: }
290:
1.29 ! djm 291: if (GSS_ERROR(major))
1.14 djm 292: ssh_gssapi_delete_ctx(ctx);
293:
294: return (!GSS_ERROR(major));
1.1 markus 295: }
296:
297: #endif /* GSSAPI */
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