summaryrefslogtreecommitdiffstats
path: root/net/sunrpc/auth_gss/gss_spkm3_token.c
blob: 3308157436d2931dcef73de989a7ed85ae8824da (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
/*
 *  linux/net/sunrpc/gss_spkm3_token.c
 *
 *  Copyright (c) 2003 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Andy Adamson <andros@umich.edu>
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. Neither the name of the University nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <linux/types.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/sunrpc/gss_spkm3.h>
#include <linux/random.h>
#include <linux/crypto.h>

#ifdef RPC_DEBUG
# define RPCDBG_FACILITY        RPCDBG_AUTH
#endif

/*
 * asn1_bitstring_len()
 *
 * calculate the asn1 bitstring length of the xdr_netobject
 */
void
asn1_bitstring_len(struct xdr_netobj *in, int *enclen, int *zerobits)
{
	int i, zbit = 0,elen = in->len;
	char *ptr;

	ptr = &in->data[in->len -1];

	/* count trailing 0's */
	for(i = in->len; i > 0; i--) {
		if (*ptr == 0) {
			ptr--;
			elen--;
		} else
			break;
	}

	/* count number of 0 bits in final octet */
	ptr = &in->data[elen - 1];
	for(i = 0; i < 8; i++) {
		short mask = 0x01;

		if (!((mask << i) & *ptr))
			zbit++;
		else
			break;
	}
	*enclen = elen;
	*zerobits = zbit;
}

/*
 * decode_asn1_bitstring()
 *
 * decode a bitstring into a buffer of the expected length.
 * enclen = bit string length
 * explen = expected length (define in rfc)
 */
int
decode_asn1_bitstring(struct xdr_netobj *out, char *in, int enclen, int explen)
{
	if (!(out->data = kzalloc(explen,GFP_NOFS)))
		return 0;
	out->len = explen;
	memcpy(out->data, in, enclen);
	return 1;
}

/*
 * SPKMInnerContextToken choice SPKM_MIC asn1 token layout
 *
 * contextid is always 16 bytes plain data. max asn1 bitstring len = 17.
 *
 * tokenlen = pos[0] to end of token (max pos[45] with MD5 cksum)
 *
 * pos  value
 * ----------
 * [0]	a4  SPKM-MIC tag
 * [1]	??  innertoken length  (max 44)
 *
 *
 * tok_hdr piece of checksum data starts here
 *
 * the maximum mic-header len = 9 + 17 = 26
 *	mic-header
 *	----------
 * [2]	30      SEQUENCE tag
 * [3]	??	mic-header length: (max 23) = TokenID + ContextID
 *
 *		TokenID  - all fields constant and can be hardcoded
 *		-------
 * [4]	  02	Type 2
 * [5]	  02	Length 2
 * [6][7] 01 01	TokenID (SPKM_MIC_TOK)
 *
 *		ContextID  - encoded length not constant, calculated
 *		---------
 * [8]	03	Type 3
 * [9]	??	encoded length
 * [10]	??	ctxzbit
 * [11]	 	contextid
 *
 * mic_header piece of checksum data ends here.
 *
 *	int-cksum - encoded length not constant, calculated
 *	---------
 * [??]	03	Type 3
 * [??]	??	encoded length
 * [??]	??	md5zbit
 * [??]	 	int-cksum (NID_md5 = 16)
 *
 * maximum SPKM-MIC innercontext token length =
 *	 10 + encoded contextid_size(17 max) + 2 + encoded
 *       cksum_size (17 maxfor NID_md5) = 46
 */

/*
 * spkm3_mic_header()
 *
 * Prepare the SPKM_MIC_TOK mic-header for check-sum calculation
 * elen: 16 byte context id asn1 bitstring encoded length
 */
void
spkm3_mic_header(unsigned char **hdrbuf, unsigned int *hdrlen, unsigned char *ctxdata, int elen, int zbit)
{
	char *hptr = *hdrbuf;
	char *top = *hdrbuf;

	*(u8 *)hptr++ = 0x30;
	*(u8 *)hptr++ = elen + 7;  /* on the wire header length */

	/* tokenid */
	*(u8 *)hptr++ = 0x02;
	*(u8 *)hptr++ = 0x02;
	*(u8 *)hptr++ = 0x01;
	*(u8 *)hptr++ = 0x01;

	/* coniextid */
	*(u8 *)hptr++ = 0x03;
	*(u8 *)hptr++ = elen + 1; /* add 1 to include zbit */
	*(u8 *)hptr++ = zbit;
	memcpy(hptr, ctxdata, elen);
	hptr += elen;
	*hdrlen = hptr - top;
}

/*
 * spkm3_mic_innercontext_token()
 *
 * *tokp points to the beginning of the SPKM_MIC token  described
 * in rfc 2025, section 3.2.1:
 *
 * toklen is the inner token length
 */
void
spkm3_make_mic_token(unsigned char **tokp, int toklen, struct xdr_netobj *mic_hdr, struct xdr_netobj *md5cksum, int md5elen, int md5zbit)
{
	unsigned char *ict = *tokp;

	*(u8 *)ict++ = 0xa4;
	*(u8 *)ict++ = toklen;
	memcpy(ict, mic_hdr->data, mic_hdr->len);
	ict += mic_hdr->len;

	*(u8 *)ict++ = 0x03;
	*(u8 *)ict++ = md5elen + 1; /* add 1 to include zbit */
	*(u8 *)ict++ = md5zbit;
	memcpy(ict, md5cksum->data, md5elen);
}

u32
spkm3_verify_mic_token(unsigned char **tokp, int *mic_hdrlen, unsigned char **cksum)
{
	struct xdr_netobj       spkm3_ctx_id = {.len =0, .data = NULL};
	unsigned char 		*ptr = *tokp;
	int 			ctxelen;
	u32     		ret = GSS_S_DEFECTIVE_TOKEN;

	/* spkm3 innercontext token preamble */
	if ((ptr[0] != 0xa4) || (ptr[2] != 0x30)) {
		dprintk("RPC:       BAD SPKM ictoken preamble\n");
		goto out;
	}

	*mic_hdrlen = ptr[3];

	/* token type */
	if ((ptr[4] != 0x02) || (ptr[5] != 0x02)) {
		dprintk("RPC:       BAD asn1 SPKM3 token type\n");
		goto out;
	}

	/* only support SPKM_MIC_TOK */
	if((ptr[6] != 0x01) || (ptr[7] != 0x01)) {
		dprintk("RPC:       ERROR unsupported SPKM3 token \n");
		goto out;
	}

	/* contextid */
	if (ptr[8] != 0x03) {
		dprintk("RPC:       BAD SPKM3 asn1 context-id type\n");
		goto out;
	}

	ctxelen = ptr[9];
	if (ctxelen > 17) {  /* length includes asn1 zbit octet */
		dprintk("RPC:       BAD SPKM3 contextid len %d\n", ctxelen);
		goto out;
	}

	/* ignore ptr[10] */

	if(!decode_asn1_bitstring(&spkm3_ctx_id, &ptr[11], ctxelen - 1, 16))
		goto out;

	/*
	* in the current implementation: the optional int-alg is not present
	* so the default int-alg (md5) is used the optional snd-seq field is
	* also not present
	*/

	if (*mic_hdrlen != 6 + ctxelen) {
		dprintk("RPC:       BAD SPKM_ MIC_TOK header len %d: we only "
				"support default int-alg (should be absent) "
				"and do not support snd-seq\n", *mic_hdrlen);
		goto out;
	}
	/* checksum */
	*cksum = (&ptr[10] + ctxelen); /* ctxelen includes ptr[10] */

	ret = GSS_S_COMPLETE;
out:
	kfree(spkm3_ctx_id.data);
	return ret;
}