1/*
2 *  linux/net/sunrpc/gss_generic_token.c
3 *
4 *  Adapted from MIT Kerberos 5-1.2.1 lib/gssapi/generic/util_token.c
5 *
6 *  Copyright (c) 2000 The Regents of the University of Michigan.
7 *  All rights reserved.
8 *
9 *  Andy Adamson   <andros@umich.edu>
10 */
11
12/*
13 * Copyright 1993 by OpenVision Technologies, Inc.
14 *
15 * Permission to use, copy, modify, distribute, and sell this software
16 * and its documentation for any purpose is hereby granted without fee,
17 * provided that the above copyright notice appears in all copies and
18 * that both that copyright notice and this permission notice appear in
19 * supporting documentation, and that the name of OpenVision not be used
20 * in advertising or publicity pertaining to distribution of the software
21 * without specific, written prior permission. OpenVision makes no
22 * representations about the suitability of this software for any
23 * purpose.  It is provided "as is" without express or implied warranty.
24 *
25 * OPENVISION DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
26 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
27 * EVENT SHALL OPENVISION BE LIABLE FOR ANY SPECIAL, INDIRECT OR
28 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
29 * USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
30 * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
31 * PERFORMANCE OF THIS SOFTWARE.
32 */
33
34#include <linux/types.h>
35#include <linux/module.h>
36#include <linux/string.h>
37#include <linux/sunrpc/sched.h>
38#include <linux/sunrpc/gss_asn1.h>
39
40
41#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
42# define RPCDBG_FACILITY        RPCDBG_AUTH
43#endif
44
45
46/* TWRITE_STR from gssapiP_generic.h */
47#define TWRITE_STR(ptr, str, len) \
48	memcpy((ptr), (char *) (str), (len)); \
49	(ptr) += (len);
50
51/* XXXX this code currently makes the assumption that a mech oid will
52   never be longer than 127 bytes.  This assumption is not inherent in
53   the interfaces, so the code can be fixed if the OSI namespace
54   balloons unexpectedly. */
55
56/* Each token looks like this:
57
580x60				tag for APPLICATION 0, SEQUENCE
59					(constructed, definite-length)
60	<length>		possible multiple bytes, need to parse/generate
61	0x06			tag for OBJECT IDENTIFIER
62		<moid_length>	compile-time constant string (assume 1 byte)
63		<moid_bytes>	compile-time constant string
64	<inner_bytes>		the ANY containing the application token
65					bytes 0,1 are the token type
66					bytes 2,n are the token data
67
68For the purposes of this abstraction, the token "header" consists of
69the sequence tag and length octets, the mech OID DER encoding, and the
70first two inner bytes, which indicate the token type.  The token
71"body" consists of everything else.
72
73*/
74
75static int
76der_length_size( int length)
77{
78	if (length < (1<<7))
79		return 1;
80	else if (length < (1<<8))
81		return 2;
82#if (SIZEOF_INT == 2)
83	else
84		return 3;
85#else
86	else if (length < (1<<16))
87		return 3;
88	else if (length < (1<<24))
89		return 4;
90	else
91		return 5;
92#endif
93}
94
95static void
96der_write_length(unsigned char **buf, int length)
97{
98	if (length < (1<<7)) {
99		*(*buf)++ = (unsigned char) length;
100	} else {
101		*(*buf)++ = (unsigned char) (der_length_size(length)+127);
102#if (SIZEOF_INT > 2)
103		if (length >= (1<<24))
104			*(*buf)++ = (unsigned char) (length>>24);
105		if (length >= (1<<16))
106			*(*buf)++ = (unsigned char) ((length>>16)&0xff);
107#endif
108		if (length >= (1<<8))
109			*(*buf)++ = (unsigned char) ((length>>8)&0xff);
110		*(*buf)++ = (unsigned char) (length&0xff);
111	}
112}
113
114/* returns decoded length, or < 0 on failure.  Advances buf and
115   decrements bufsize */
116
117static int
118der_read_length(unsigned char **buf, int *bufsize)
119{
120	unsigned char sf;
121	int ret;
122
123	if (*bufsize < 1)
124		return -1;
125	sf = *(*buf)++;
126	(*bufsize)--;
127	if (sf & 0x80) {
128		if ((sf &= 0x7f) > ((*bufsize)-1))
129			return -1;
130		if (sf > SIZEOF_INT)
131			return -1;
132		ret = 0;
133		for (; sf; sf--) {
134			ret = (ret<<8) + (*(*buf)++);
135			(*bufsize)--;
136		}
137	} else {
138		ret = sf;
139	}
140
141	return ret;
142}
143
144/* returns the length of a token, given the mech oid and the body size */
145
146int
147g_token_size(struct xdr_netobj *mech, unsigned int body_size)
148{
149	/* set body_size to sequence contents size */
150	body_size += 2 + (int) mech->len;         /* NEED overflow check */
151	return 1 + der_length_size(body_size) + body_size;
152}
153
154EXPORT_SYMBOL_GPL(g_token_size);
155
156/* fills in a buffer with the token header.  The buffer is assumed to
157   be the right size.  buf is advanced past the token header */
158
159void
160g_make_token_header(struct xdr_netobj *mech, int body_size, unsigned char **buf)
161{
162	*(*buf)++ = 0x60;
163	der_write_length(buf, 2 + mech->len + body_size);
164	*(*buf)++ = 0x06;
165	*(*buf)++ = (unsigned char) mech->len;
166	TWRITE_STR(*buf, mech->data, ((int) mech->len));
167}
168
169EXPORT_SYMBOL_GPL(g_make_token_header);
170
171/*
172 * Given a buffer containing a token, reads and verifies the token,
173 * leaving buf advanced past the token header, and setting body_size
174 * to the number of remaining bytes.  Returns 0 on success,
175 * G_BAD_TOK_HEADER for a variety of errors, and G_WRONG_MECH if the
176 * mechanism in the token does not match the mech argument.  buf and
177 * *body_size are left unmodified on error.
178 */
179u32
180g_verify_token_header(struct xdr_netobj *mech, int *body_size,
181		      unsigned char **buf_in, int toksize)
182{
183	unsigned char *buf = *buf_in;
184	int seqsize;
185	struct xdr_netobj toid;
186	int ret = 0;
187
188	if ((toksize-=1) < 0)
189		return G_BAD_TOK_HEADER;
190	if (*buf++ != 0x60)
191		return G_BAD_TOK_HEADER;
192
193	if ((seqsize = der_read_length(&buf, &toksize)) < 0)
194		return G_BAD_TOK_HEADER;
195
196	if (seqsize != toksize)
197		return G_BAD_TOK_HEADER;
198
199	if ((toksize-=1) < 0)
200		return G_BAD_TOK_HEADER;
201	if (*buf++ != 0x06)
202		return G_BAD_TOK_HEADER;
203
204	if ((toksize-=1) < 0)
205		return G_BAD_TOK_HEADER;
206	toid.len = *buf++;
207
208	if ((toksize-=toid.len) < 0)
209		return G_BAD_TOK_HEADER;
210	toid.data = buf;
211	buf+=toid.len;
212
213	if (! g_OID_equal(&toid, mech))
214		ret = G_WRONG_MECH;
215
216   /* G_WRONG_MECH is not returned immediately because it's more important
217      to return G_BAD_TOK_HEADER if the token header is in fact bad */
218
219	if ((toksize-=2) < 0)
220		return G_BAD_TOK_HEADER;
221
222	if (ret)
223		return ret;
224
225	*buf_in = buf;
226	*body_size = toksize;
227
228	return ret;
229}
230
231EXPORT_SYMBOL_GPL(g_verify_token_header);
232