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authorcvs2svn <admin@example.com>2015-03-08 16:48:48 +0000
committercvs2svn <admin@example.com>2015-03-08 16:48:48 +0000
commitda1a9ad3a4a867ba6569c05e6fca66d7f296c553 (patch)
tree44872802e872bdfd60730fa9cf01d9d5751251c1 /src/lib/libssl/bs_ber.c
parent973703db67a8e73d70e63afa8f2cde19da09144d (diff)
downloadopenbsd-OPENBSD_5_7_BASE.tar.gz
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This commit was manufactured by cvs2git to create tag 'OPENBSD_5_7_BASE'.OPENBSD_5_7_BASE
Diffstat (limited to 'src/lib/libssl/bs_ber.c')
-rw-r--r--src/lib/libssl/bs_ber.c252
1 files changed, 0 insertions, 252 deletions
diff --git a/src/lib/libssl/bs_ber.c b/src/lib/libssl/bs_ber.c
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index cfc9475f9a..0000000000
--- a/src/lib/libssl/bs_ber.c
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1/* $OpenBSD: bs_ber.c,v 1.2 2015/02/06 22:22:33 doug Exp $ */
2/*
3 * Copyright (c) 2014, Google Inc.
4 *
5 * Permission to use, copy, modify, and/or distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
12 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
14 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
15 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
16
17#include <string.h>
18
19#include <openssl/opensslconf.h>
20
21#include "bytestring.h"
22
23/*
24 * kMaxDepth is a just a sanity limit. The code should be such that the length
25 * of the input being processes always decreases. None the less, a very large
26 * input could otherwise cause the stack to overflow.
27 */
28static const unsigned kMaxDepth = 2048;
29
30/*
31 * cbs_find_ber walks an ASN.1 structure in |orig_in| and sets |*ber_found|
32 * depending on whether an indefinite length element was found. The value of
33 * |in| is not changed. It returns one on success (i.e. |*ber_found| was set)
34 * and zero on error.
35 */
36static int
37cbs_find_ber(CBS *orig_in, char *ber_found, unsigned depth)
38{
39 CBS in;
40
41 if (depth > kMaxDepth)
42 return 0;
43
44 CBS_init(&in, CBS_data(orig_in), CBS_len(orig_in));
45 *ber_found = 0;
46
47 while (CBS_len(&in) > 0) {
48 CBS contents;
49 unsigned tag;
50 size_t header_len;
51
52 if (!CBS_get_any_asn1_element(&in, &contents, &tag,
53 &header_len))
54 return 0;
55
56 if (CBS_len(&contents) == header_len && header_len > 0 &&
57 CBS_data(&contents)[header_len-1] == 0x80) {
58 *ber_found = 1;
59 return 1;
60 }
61 if (tag & CBS_ASN1_CONSTRUCTED) {
62 if (!CBS_skip(&contents, header_len) ||
63 !cbs_find_ber(&contents, ber_found, depth + 1))
64 return 0;
65 }
66 }
67
68 return 1;
69}
70
71/*
72 * is_primitive_type returns true if |tag| likely a primitive type. Normally
73 * one can just test the "constructed" bit in the tag but, in BER, even
74 * primitive tags can have the constructed bit if they have indefinite
75 * length.
76 */
77static char
78is_primitive_type(unsigned tag)
79{
80 return (tag & 0xc0) == 0 &&
81 (tag & 0x1f) != (CBS_ASN1_SEQUENCE & 0x1f) &&
82 (tag & 0x1f) != (CBS_ASN1_SET & 0x1f);
83}
84
85/*
86 * is_eoc returns true if |header_len| and |contents|, as returned by
87 * |CBS_get_any_asn1_element|, indicate an "end of contents" (EOC) value.
88 */
89static char
90is_eoc(size_t header_len, CBS *contents)
91{
92 return header_len == 2 && CBS_len(contents) == 2 &&
93 memcmp(CBS_data(contents), "\x00\x00", 2) == 0;
94}
95
96/*
97 * cbs_convert_ber reads BER data from |in| and writes DER data to |out|. If
98 * |squash_header| is set then the top-level of elements from |in| will not
99 * have their headers written. This is used when concatenating the fragments of
100 * an indefinite length, primitive value. If |looking_for_eoc| is set then any
101 * EOC elements found will cause the function to return after consuming it.
102 * It returns one on success and zero on error.
103 */
104static int
105cbs_convert_ber(CBS *in, CBB *out, char squash_header, char looking_for_eoc,
106 unsigned depth)
107{
108 if (depth > kMaxDepth)
109 return 0;
110
111 while (CBS_len(in) > 0) {
112 CBS contents;
113 unsigned tag;
114 size_t header_len;
115 CBB *out_contents, out_contents_storage;
116
117 if (!CBS_get_any_asn1_element(in, &contents, &tag, &header_len))
118 return 0;
119
120 out_contents = out;
121
122 if (CBS_len(&contents) == header_len) {
123 if (is_eoc(header_len, &contents))
124 return looking_for_eoc;
125
126 if (header_len > 0 &&
127 CBS_data(&contents)[header_len - 1] == 0x80) {
128 /*
129 * This is an indefinite length element. If
130 * it's a SEQUENCE or SET then we just need to
131 * write the out the contents as normal, but
132 * with a concrete length prefix.
133 *
134 * If it's a something else then the contents
135 * will be a series of BER elements of the same
136 * type which need to be concatenated.
137 */
138 const char context_specific = (tag & 0xc0)
139 == 0x80;
140 char squash_child_headers =
141 is_primitive_type(tag);
142
143 /*
144 * This is a hack, but it sufficies to handle
145 * NSS's output. If we find an indefinite
146 * length, context-specific tag with a definite,
147 * primtive tag inside it, then we assume that
148 * the context-specific tag is implicit and the
149 * tags within are fragments of a primitive type
150 * that need to be concatenated.
151 */
152 if (context_specific &&
153 (tag & CBS_ASN1_CONSTRUCTED)) {
154 CBS in_copy, inner_contents;
155 unsigned inner_tag;
156 size_t inner_header_len;
157
158 CBS_init(&in_copy, CBS_data(in),
159 CBS_len(in));
160 if (!CBS_get_any_asn1_element(&in_copy,
161 &inner_contents, &inner_tag,
162 &inner_header_len))
163 return 0;
164
165 if (CBS_len(&inner_contents) >
166 inner_header_len &&
167 is_primitive_type(inner_tag))
168 squash_child_headers = 1;
169 }
170
171 if (!squash_header) {
172 unsigned out_tag = tag;
173
174 if (squash_child_headers)
175 out_tag &=
176 ~CBS_ASN1_CONSTRUCTED;
177
178 if (!CBB_add_asn1(out,
179 &out_contents_storage, out_tag))
180 return 0;
181
182 out_contents = &out_contents_storage;
183 }
184
185 if (!cbs_convert_ber(in, out_contents,
186 squash_child_headers,
187 1 /* looking for eoc */, depth + 1))
188 return 0;
189
190 if (out_contents != out && !CBB_flush(out))
191 return 0;
192
193 continue;
194 }
195 }
196
197 if (!squash_header) {
198 if (!CBB_add_asn1(out, &out_contents_storage, tag))
199 return 0;
200
201 out_contents = &out_contents_storage;
202 }
203
204 if (!CBS_skip(&contents, header_len))
205 return 0;
206
207 if (tag & CBS_ASN1_CONSTRUCTED) {
208 if (!cbs_convert_ber(&contents, out_contents,
209 0 /* don't squash header */,
210 0 /* not looking for eoc */, depth + 1))
211 return 0;
212 } else {
213 if (!CBB_add_bytes(out_contents, CBS_data(&contents),
214 CBS_len(&contents)))
215 return 0;
216 }
217
218 if (out_contents != out && !CBB_flush(out))
219 return 0;
220 }
221
222 return looking_for_eoc == 0;
223}
224
225int
226CBS_asn1_ber_to_der(CBS *in, uint8_t **out, size_t *out_len)
227{
228 CBB cbb;
229
230 /*
231 * First, do a quick walk to find any indefinite-length elements. Most
232 * of the time we hope that there aren't any and thus we can quickly
233 * return.
234 */
235 char conversion_needed;
236 if (!cbs_find_ber(in, &conversion_needed, 0))
237 return 0;
238
239 if (!conversion_needed) {
240 *out = NULL;
241 *out_len = 0;
242 return 1;
243 }
244
245 CBB_init(&cbb, CBS_len(in));
246 if (!cbs_convert_ber(in, &cbb, 0, 0, 0)) {
247 CBB_cleanup(&cbb);
248 return 0;
249 }
250
251 return CBB_finish(&cbb, out, out_len);
252}
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