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GCC Code Coverage Report

Directory:	./		Exec	Total	Coverage
File:	lib/libssl/bs_ber.c	Lines:	82	105	78.1 %
Date:	2017-11-07	Branches:	58	90	64.4 %


/*	$OpenBSD: bs_ber.c,v 1.9 2016/12/03 12:34:35 jsing Exp $	*/
/*
 * Copyright (c) 2014, Google Inc.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */

#include <string.h>

#include <openssl/opensslconf.h>

#include "bytestring.h"

/*
 * kMaxDepth is a just a sanity limit. The code should be such that the length
 * of the input being processes always decreases. None the less, a very large
 * input could otherwise cause the stack to overflow.
 */
static const unsigned int kMaxDepth = 2048;

/* Non-strict version that allows a relaxed DER with indefinite form. */
static int
cbs_nonstrict_get_any_asn1_element(CBS *cbs, CBS *out, unsigned int *out_tag,
    size_t *out_header_len)
{
	return cbs_get_any_asn1_element_internal(cbs, out,
	    out_tag, out_header_len, 0);
}

/*
 * cbs_find_indefinite walks an ASN.1 structure in |orig_in| and sets
 * |*indefinite_found| depending on whether an indefinite length element was
 * found. The value of |orig_in| is not modified.
 *
 * Returns one on success (i.e. |*indefinite_found| was set) and zero on error.
 */
static int
cbs_find_indefinite(const CBS *orig_in, char *indefinite_found,
    unsigned int depth)
{
	CBS in;

	if (depth > kMaxDepth)
		return 0;

	CBS_init(&in, CBS_data(orig_in), CBS_len(orig_in));

	while (CBS_len(&in) > 0) {
		CBS contents;
		unsigned int tag;
		size_t header_len;

		if (!cbs_nonstrict_get_any_asn1_element(&in, &contents, &tag,
		    &header_len))
			return 0;

		/* Indefinite form not allowed by DER. */
		if (CBS_len(&contents) == header_len && header_len > 0 &&
		    CBS_data(&contents)[header_len - 1] == 0x80) {
			*indefinite_found = 1;
			return 1;
		}
		if (tag & CBS_ASN1_CONSTRUCTED) {
			if (!CBS_skip(&contents, header_len) ||
			    !cbs_find_indefinite(&contents, indefinite_found,
			    depth + 1))
				return 0;
		}
	}

	*indefinite_found = 0;
	return 1;
}

/*
 * is_primitive_type returns true if |tag| likely a primitive type. Normally
 * one can just test the "constructed" bit in the tag but, in BER, even
 * primitive tags can have the constructed bit if they have indefinite
 * length.
 */
static char
is_primitive_type(unsigned int tag)
{
	return (tag & 0xc0) == 0 &&
	    (tag & 0x1f) != (CBS_ASN1_SEQUENCE & 0x1f) &&
	    (tag & 0x1f) != (CBS_ASN1_SET & 0x1f);
}

/*
 * is_eoc returns true if |header_len| and |contents|, as returned by
 * |cbs_nonstrict_get_any_asn1_element|, indicate an "end of contents" (EOC)
 * value.
 */
static char
is_eoc(size_t header_len, CBS *contents)
{
	const unsigned char eoc[] = {0x0, 0x0};

	return header_len == 2 && CBS_mem_equal(contents, eoc, 2);
}

/*
 * cbs_convert_indefinite reads data with DER encoding (but relaxed to allow
 * indefinite form) from |in| and writes definite form DER data to |out|. If
 * |squash_header| is set then the top-level of elements from |in| will not
 * have their headers written. This is used when concatenating the fragments of
 * an indefinite length, primitive value. If |looking_for_eoc| is set then any
 * EOC elements found will cause the function to return after consuming it.
 * It returns one on success and zero on error.
 */
static int
cbs_convert_indefinite(CBS *in, CBB *out, char squash_header,
    char looking_for_eoc, unsigned int depth)
{
	if (depth > kMaxDepth)
		return 0;

	while (CBS_len(in) > 0) {
		CBS contents;
		unsigned int tag;
		size_t header_len;
		CBB *out_contents, out_contents_storage;

		if (!cbs_nonstrict_get_any_asn1_element(in, &contents, &tag,
		    &header_len))
			return 0;

		out_contents = out;

		if (CBS_len(&contents) == header_len) {
			if (is_eoc(header_len, &contents))
				return looking_for_eoc;

			if (header_len > 0 &&
			    CBS_data(&contents)[header_len - 1] == 0x80) {
				/*
				 * This is an indefinite length element. If
				 * it's a SEQUENCE or SET then we just need to
				 * write the out the contents as normal, but
				 * with a concrete length prefix.
				 *
				 * If it's a something else then the contents
				 * will be a series of DER elements of the same
				 * type which need to be concatenated.
				 */
				const char context_specific = (tag & 0xc0)
				    == 0x80;
				char squash_child_headers =
				    is_primitive_type(tag);

				/*
				 * This is a hack, but it sufficies to handle
				 * NSS's output. If we find an indefinite
				 * length, context-specific tag with a definite,
				 * primtive tag inside it, then we assume that
				 * the context-specific tag is implicit and the
				 * tags within are fragments of a primitive type
				 * that need to be concatenated.
				 */
				if (context_specific &&
				    (tag & CBS_ASN1_CONSTRUCTED)) {
					CBS in_copy, inner_contents;
					unsigned int inner_tag;
					size_t inner_header_len;

					CBS_init(&in_copy, CBS_data(in),
					    CBS_len(in));
					if (!cbs_nonstrict_get_any_asn1_element(
					    &in_copy, &inner_contents,
					    &inner_tag, &inner_header_len))
						return 0;

					if (CBS_len(&inner_contents) >
					    inner_header_len &&
					    is_primitive_type(inner_tag))
						squash_child_headers = 1;
				}

				if (!squash_header) {
					unsigned int out_tag = tag;

					if (squash_child_headers)
						out_tag &=
						    ~CBS_ASN1_CONSTRUCTED;

					if (!CBB_add_asn1(out,
					    &out_contents_storage, out_tag))
						return 0;

					out_contents = &out_contents_storage;
				}

				if (!cbs_convert_indefinite(in, out_contents,
				    squash_child_headers,
				    1 /* looking for eoc */, depth + 1))
					return 0;

				if (out_contents != out && !CBB_flush(out))
					return 0;

				continue;
			}
		}

		if (!squash_header) {
			if (!CBB_add_asn1(out, &out_contents_storage, tag))
				return 0;

			out_contents = &out_contents_storage;
		}

		if (!CBS_skip(&contents, header_len))
			return 0;

		if (tag & CBS_ASN1_CONSTRUCTED) {
			if (!cbs_convert_indefinite(&contents, out_contents,
			    0 /* don't squash header */,
			    0 /* not looking for eoc */, depth + 1))
				return 0;
		} else {
			if (!CBB_add_bytes(out_contents, CBS_data(&contents),
			    CBS_len(&contents)))
				return 0;
		}

		if (out_contents != out && !CBB_flush(out))
			return 0;
	}

	return looking_for_eoc == 0;
}

int
CBS_asn1_indefinite_to_definite(CBS *in, uint8_t **out, size_t *out_len)
{
	CBB cbb;

	/*
	 * First, do a quick walk to find any indefinite-length elements. Most
	 * of the time we hope that there aren't any and thus we can quickly
	 * return.
	 */
	char conversion_needed;
	if (!cbs_find_indefinite(in, &conversion_needed, 0))
		return 0;

	if (!conversion_needed) {
		*out = NULL;
		*out_len = 0;
		return 1;
	}

	if (!CBB_init(&cbb, CBS_len(in)))
		return 0;
	if (!cbs_convert_indefinite(in, &cbb, 0, 0, 0)) {
		CBB_cleanup(&cbb);
		return 0;
	}

	return CBB_finish(&cbb, out, out_len);
}


Generated by: GCOVR (Version 3.3)

Line	Branch	Exec	Source
1			/* $OpenBSD: bs_ber.c,v 1.9 2016/12/03 12:34:35 jsing 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			*/
28			static const unsigned int kMaxDepth = 2048;
29
30			/* Non-strict version that allows a relaxed DER with indefinite form. */
31			static int
32			cbs_nonstrict_get_any_asn1_element(CBS cbs, CBS out, unsigned int *out_tag,
33			size_t *out_header_len)
34			{
35		248	return cbs_get_any_asn1_element_internal(cbs, out,
36			out_tag, out_header_len, 0);
37			}
38
39			/*
40			* cbs_find_indefinite walks an ASN.1 structure in \|orig_in\| and sets
41			* \|*indefinite_found\| depending on whether an indefinite length element was
42			* found. The value of \|orig_in\| is not modified.
43			*
44			* Returns one on success (i.e. \|*indefinite_found\| was set) and zero on error.
45			*/
46			static int
47			cbs_find_indefinite(const CBS orig_in, char indefinite_found,
48			unsigned int depth)
49			{
50		32	CBS in;
51
52	✗✓	16	if (depth > kMaxDepth)
53			return 0;
54
55		16	CBS_init(&in, CBS_data(orig_in), CBS_len(orig_in));
56
57	✓✓	36	while (CBS_len(&in) > 0) {
58		16	CBS contents;
59		16	unsigned int tag;
60		16	size_t header_len;
61
62	✗✓	16	if (!cbs_nonstrict_get_any_asn1_element(&in, &contents, &tag,
63			&header_len))
64			return 0;
65
66			/* Indefinite form not allowed by DER. */
67	✓✓✓✗	28	if (CBS_len(&contents) == header_len && header_len > 0 &&
68		12	CBS_data(&contents)[header_len - 1] == 0x80) {
69		12	*indefinite_found = 1;
70		12	return 1;
71			}
72	✗✓	4	if (tag & CBS_ASN1_CONSTRUCTED) {
73			if (!CBS_skip(&contents, header_len) \|\|
74			!cbs_find_indefinite(&contents, indefinite_found,
75			depth + 1))
76			return 0;
77			}
78	✓✓	20	}
79
80		4	*indefinite_found = 0;
81		4	return 1;
82		16	}
83
84			/*
85			* is_primitive_type returns true if \|tag\| likely a primitive type. Normally
86			* one can just test the "constructed" bit in the tag but, in BER, even
87			* primitive tags can have the constructed bit if they have indefinite
88			* length.
89			*/
90			static char
91			is_primitive_type(unsigned int tag)
92			{
93	✓✓	72	return (tag & 0xc0) == 0 &&
94	✓✓	44	(tag & 0x1f) != (CBS_ASN1_SEQUENCE & 0x1f) &&
95		8	(tag & 0x1f) != (CBS_ASN1_SET & 0x1f);
96			}
97
98			/*
99			* is_eoc returns true if \|header_len\| and \|contents\|, as returned by
100			* \|cbs_nonstrict_get_any_asn1_element\|, indicate an "end of contents" (EOC)
101			* value.
102			*/
103			static char
104			is_eoc(size_t header_len, CBS *contents)
105			{
106			const unsigned char eoc[] = {0x0, 0x0};
107
108	✓✗	208	return header_len == 2 && CBS_mem_equal(contents, eoc, 2);
109			}
110
111			/*
112			* cbs_convert_indefinite reads data with DER encoding (but relaxed to allow
113			* indefinite form) from \|in\| and writes definite form DER data to \|out\|. If
114			* \|squash_header\| is set then the top-level of elements from \|in\| will not
115			* have their headers written. This is used when concatenating the fragments of
116			* an indefinite length, primitive value. If \|looking_for_eoc\| is set then any
117			* EOC elements found will cause the function to return after consuming it.
118			* It returns one on success and zero on error.
119			*/
120			static int
121			cbs_convert_indefinite(CBS in, CBB out, char squash_header,
122			char looking_for_eoc, unsigned int depth)
123			{
124	✗✓	96	if (depth > kMaxDepth)
125			return 0;
126
127	✓✓	128	while (CBS_len(in) > 0) {
128		104	CBS contents;
129		104	unsigned int tag;
130		104	size_t header_len;
131		104	CBB *out_contents, out_contents_storage;
132
133	✗✓	104	if (!cbs_nonstrict_get_any_asn1_element(in, &contents, &tag,
134			&header_len))
135			return 0;
136
137			out_contents = out;
138
139	✓✓	104	if (CBS_len(&contents) == header_len) {
140	✓✓	52	if (is_eoc(header_len, &contents))
141		24	return looking_for_eoc;
142
143	✓✗✓✓	56	if (header_len > 0 &&
144		28	CBS_data(&contents)[header_len - 1] == 0x80) {
145			/*
146			* This is an indefinite length element. If
147			* it's a SEQUENCE or SET then we just need to
148			* write the out the contents as normal, but
149			* with a concrete length prefix.
150			*
151			* If it's a something else then the contents
152			* will be a series of DER elements of the same
153			* type which need to be concatenated.
154			*/
155		48	const char context_specific = (tag & 0xc0)
156		24	== 0x80;
157			char squash_child_headers =
158		24	is_primitive_type(tag);
159
160			/*
161			* This is a hack, but it sufficies to handle
162			* NSS's output. If we find an indefinite
163			* length, context-specific tag with a definite,
164			* primtive tag inside it, then we assume that
165			* the context-specific tag is implicit and the
166			* tags within are fragments of a primitive type
167			* that need to be concatenated.
168			*/
169	✓✓✓✗	28	if (context_specific &&
170		4	(tag & CBS_ASN1_CONSTRUCTED)) {
171		4	CBS in_copy, inner_contents;
172		4	unsigned int inner_tag;
173		4	size_t inner_header_len;
174
175		8	CBS_init(&in_copy, CBS_data(in),
176		4	CBS_len(in));
177	✗✓	4	if (!cbs_nonstrict_get_any_asn1_element(
178			&in_copy, &inner_contents,
179			&inner_tag, &inner_header_len))
180			return 0;
181
182	✗✗	8	if (CBS_len(&inner_contents) >
183	✗✓	8	inner_header_len &&
184			is_primitive_type(inner_tag))
185			squash_child_headers = 1;
186	✓✗	8	}
187
188	✓✗	24	if (!squash_header) {
189		24	unsigned int out_tag = tag;
190
191	✓✓	24	if (squash_child_headers)
192		8	out_tag &=
193			~CBS_ASN1_CONSTRUCTED;
194
195	✗✓	24	if (!CBB_add_asn1(out,
196			&out_contents_storage, out_tag))
197			return 0;
198
199			out_contents = &out_contents_storage;
200	✓✗	24	}
201
202	✗✓	24	if (!cbs_convert_indefinite(in, out_contents,
203			squash_child_headers,
204		24	1 /* looking for eoc */, depth + 1))
205			return 0;
206
207	✓✗✗✓	48	if (out_contents != out && !CBB_flush(out))
208			return 0;
209
210		24	continue;
211			}
212			}
213
214	✓✓	56	if (!squash_header) {
215	✗✓	44	if (!CBB_add_asn1(out, &out_contents_storage, tag))
216			return 0;
217
218			out_contents = &out_contents_storage;
219		44	}
220
221	✗✓	56	if (!CBS_skip(&contents, header_len))
222			return 0;
223
224	✓✓	56	if (tag & CBS_ASN1_CONSTRUCTED) {
225	✗✓	12	if (!cbs_convert_indefinite(&contents, out_contents,
226			0 /* don't squash header */,
227		12	0 /* not looking for eoc */, depth + 1))
228			return 0;
229			} else {
230	✗✓	88	if (!CBB_add_bytes(out_contents, CBS_data(&contents),
231		44	CBS_len(&contents)))
232			return 0;
233			}
234
235	✓✓✗✓	100	if (out_contents != out && !CBB_flush(out))
236			return 0;
237	✓✓	160	}
238
239		24	return looking_for_eoc == 0;
240		48	}
241
242			int
243			CBS_asn1_indefinite_to_definite(CBS in, uint8_t out, size_t out_len)
244			{
245		32	CBB cbb;
246
247			/*
248			* First, do a quick walk to find any indefinite-length elements. Most
249			* of the time we hope that there aren't any and thus we can quickly
250			* return.
251			*/
252		16	char conversion_needed;
253	✗✓	16	if (!cbs_find_indefinite(in, &conversion_needed, 0))
254			return 0;
255
256	✓✓	16	if (!conversion_needed) {
257		4	*out = NULL;
258		4	*out_len = 0;
259		4	return 1;
260			}
261
262	✗✓	12	if (!CBB_init(&cbb, CBS_len(in)))
263			return 0;
264	✗✓	12	if (!cbs_convert_indefinite(in, &cbb, 0, 0, 0)) {
265			CBB_cleanup(&cbb);
266			return 0;
267			}
268
269		12	return CBB_finish(&cbb, out, out_len);
270		16	}