1/*-
2 * Copyright (c) 2018, Juniper Networks, Inc.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
14 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
15 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
16 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
17 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
18 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
19 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include <sys/cdefs.h>
27#include <libsecureboot.h>
28
29#include "decode.h"
30
31char *
32octets2hex(unsigned char *ptr, size_t n)
33{
34	char *hex;
35	char *cp;
36	size_t i;
37
38	hex = malloc(2 * n + 1);
39	if (hex != NULL) {
40		for (i = 0, cp = hex; i < n; i++) {
41			snprintf(&cp[i*2], 3, "%02X", ptr[i]);
42		}
43	}
44	return (hex);
45}
46
47unsigned char *
48i2octets(int n, size_t i)
49{
50	static unsigned char o[16];
51	int x, j;
52
53	if (n > 15)
54		return (NULL);
55	for (j = 0, x = n - 1; x >= 0; x--, j++) {
56		o[j] = (unsigned char)((i & (0xff << x * 8)) >> x * 8);
57	}
58	return (o);
59}
60
61int
62octets2i(unsigned char *ptr, size_t n)
63{
64	size_t i;
65	int val;
66
67	for (val = i = 0; i < n; i++) {
68		val |= (*ptr++ << ((n - i - 1) * 8));
69	}
70	return (val);
71}
72
73/**
74 * @brief decode packet tag
75 *
76 * Also indicate if new/old and in the later case
77 * the length type
78 *
79 * @sa rfc4880:4.2
80 */
81int
82decode_tag(unsigned char *ptr, int *isnew, int *ltype)
83{
84	int tag;
85
86	if (!ptr || !isnew || !ltype)
87		return (-1);
88	tag = *ptr;
89
90	if (!(tag & OPENPGP_TAG_ISTAG))
91		return (-1);		/* we are lost! */
92	*isnew = tag & OPENPGP_TAG_ISNEW;
93	if (*isnew) {
94		*ltype = -1;		/* irrelevant */
95		tag &= OPENPGP_TAG_NEW_MASK;
96	} else {
97		*ltype = tag & OPENPGP_TAG_OLD_TYPE;
98		tag = (tag & OPENPGP_TAG_OLD_MASK) >> 2;
99	}
100	return (tag);
101}
102
103/**
104 * @brief return packet length
105 *
106 * @sa rfc4880:4.2.2
107 */
108static int
109decode_new_len(unsigned char **pptr)
110{
111	unsigned char *ptr;
112	int len = -1;
113
114	if (pptr == NULL)
115		return (-1);
116	ptr = *pptr;
117
118	if (!(*ptr < 224 || *ptr == 255))
119		return (-1);		/* not supported */
120
121	if (*ptr < 192)
122		len = *ptr++;
123	else if (*ptr < 224) {
124		len = ((*ptr - 192) << 8) + *(ptr+1) + 192;
125		ptr++;
126	} else if (*ptr == 255) {
127		len = (*ptr++ << 24);
128		len |= (*ptr++ << 16);
129		len |= (*ptr++ < 8);
130		len |= *ptr++;
131	}
132
133	*pptr = ptr;
134	return (len);
135}
136
137/**
138 * @brief return packet length
139 *
140 * @sa rfc4880:4.2.1
141 */
142static int
143decode_len(unsigned char **pptr, int ltype)
144{
145	unsigned char *ptr;
146	int len;
147
148	if (ltype < 0)
149		return (decode_new_len(pptr));
150
151	if (pptr == NULL)
152		return (-1);
153
154	ptr = *pptr;
155
156	switch (ltype) {
157	case 0:
158		len = *ptr++;
159		break;
160	case 1:
161		len = (*ptr++ << 8);
162		len |= *ptr++;
163		break;
164	case 2:
165		len =  *ptr++ << 24;
166		len |= *ptr++ << 16;
167		len |= *ptr++ << 8;
168		len |= *ptr++;
169		break;
170	case 3:
171	default:
172		/* Not supported */
173		len = -1;
174	}
175
176	*pptr = ptr;
177	return (len);
178}
179
180/**
181 * @brief return pointer and length of an mpi
182 *
183 * @sa rfc4880:3.2
184 */
185unsigned char *
186decode_mpi(unsigned char **pptr, size_t *sz)
187{
188	unsigned char *data;
189	unsigned char *ptr;
190	size_t mlen;
191
192	if (pptr == NULL || sz == NULL)
193		return (NULL);
194
195	ptr = *pptr;
196
197	mlen = (size_t)(*ptr++ << 8);
198	mlen |= (size_t)*ptr++;		/* number of bits */
199	mlen = (mlen + 7) / 8;		/* number of bytes */
200	*sz = mlen;
201	data = ptr;
202	ptr += mlen;
203	*pptr = ptr;
204	return (data);
205}
206
207/**
208 * @brief return an OpenSSL BIGNUM from mpi
209 *
210 * @sa rfc4880:3.2
211 */
212#ifdef USE_BEARSSL
213unsigned char *
214mpi2bn(unsigned char **pptr, size_t *sz)
215{
216	return (decode_mpi(pptr, sz));
217}
218#else
219BIGNUM *
220mpi2bn(unsigned char **pptr)
221{
222	BIGNUM *bn = NULL;
223	unsigned char *ptr;
224	int mlen;
225
226	if (pptr == NULL)
227		return (NULL);
228
229	ptr = *pptr;
230
231	mlen = (*ptr++ << 8);
232	mlen |= *ptr++;			/* number of bits */
233	mlen = (mlen + 7) / 8;		/* number of bytes */
234	bn = BN_bin2bn(ptr, mlen, NULL);
235	ptr += mlen;
236	*pptr = ptr;
237
238	return (bn);
239}
240#endif
241
242/**
243 * @brief decode a packet
244 *
245 * If want is set, check that the packet tag matches
246 * if all good, call the provided decoder with its arg
247 *
248 * @return count of unconsumed data
249 *
250 * @sa rfc4880:4.2
251 */
252int
253decode_packet(int want, unsigned char **pptr, size_t nbytes,
254    decoder_t decoder, void *decoder_arg)
255{
256	int tag;
257	unsigned char *ptr;
258	unsigned char *nptr;
259	int isnew, ltype;
260	int len;
261	int hlen;
262	int rc = 0;
263
264	nptr = ptr = *pptr;
265
266	tag = decode_tag(ptr, &isnew, &ltype);
267
268	if (want > 0 && tag != want)
269		return (-1);
270	ptr++;
271
272	len = rc = decode_len(&ptr, ltype);
273	hlen = (int)(ptr - nptr);
274	nptr = ptr + len;		/* consume it */
275
276	if (decoder)
277		rc = decoder(tag, &ptr, len, decoder_arg);
278	*pptr = nptr;
279	nbytes -= (size_t)(hlen + len);
280	if (rc < 0)
281		return (rc);		/* error */
282	return ((int)nbytes);		/* unconsumed data */
283}
284
285/**
286 * @brief decode a sub packet
287 *
288 * @sa rfc4880:5.2.3.1
289 */
290unsigned char *
291decode_subpacket(unsigned char **pptr, int *stag, int *sz)
292{
293	unsigned char *ptr;
294	int len;
295
296	ptr = *pptr;
297	len = decode_len(&ptr, -1);
298	*sz = (int)(len + ptr - *pptr);
299	*pptr = ptr + len;
300	*stag = *ptr++;
301	return (ptr);
302}
303