-/* $OpenBSD: bs_ber.c,v 1.4 2015/04/29 02:11:09 doug Exp $ */
+/* $OpenBSD: bs_ber.c,v 1.5 2015/06/15 07:35:49 doug Exp $ */
/*
* Copyright (c) 2014, Google Inc.
*
*/
static const unsigned 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 *out_tag,
+ size_t *out_header_len)
+{
+ return cbs_get_any_asn1_element_internal(cbs, out,
+ out_tag, out_header_len, 0);
+}
+
/*
* cbs_find_ber walks an ASN.1 structure in |orig_in| and sets |*ber_found|
* depending on whether an indefinite length element was found. The value of
unsigned tag;
size_t header_len;
- if (!CBS_get_any_asn1_element(&in, &contents, &tag,
+ 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) {
*ber_found = 1;
/*
* is_eoc returns true if |header_len| and |contents|, as returned by
- * |CBS_get_any_asn1_element|, indicate an "end of contents" (EOC) value.
+ * |cbs_nonstrict_get_any_asn1_element|, indicate an "end of contents" (EOC)
+ * value.
*/
static char
is_eoc(size_t header_len, CBS *contents)
size_t header_len;
CBB *out_contents, out_contents_storage;
- if (!CBS_get_any_asn1_element(in, &contents, &tag, &header_len))
+ if (!cbs_nonstrict_get_any_asn1_element(in, &contents, &tag,
+ &header_len))
return 0;
out_contents = out;
CBS_init(&in_copy, CBS_data(in),
CBS_len(in));
- if (!CBS_get_any_asn1_element(&in_copy,
- &inner_contents, &inner_tag,
- &inner_header_len))
+ if (!cbs_nonstrict_get_any_asn1_element(
+ &in_copy, &inner_contents,
+ &inner_tag, &inner_header_len))
return 0;
if (CBS_len(&inner_contents) >
-/* $OpenBSD: bs_cbs.c,v 1.8 2015/06/13 08:46:00 doug Exp $ */
+/* $OpenBSD: bs_cbs.c,v 1.9 2015/06/15 07:35:49 doug Exp $ */
/*
* Copyright (c) 2014, Google Inc.
*
int
CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag,
size_t *out_header_len)
+{
+ return cbs_get_any_asn1_element_internal(cbs, out, out_tag,
+ out_header_len, 1);
+}
+
+/*
+ * Review X.690 for details on ASN.1 DER encoding.
+ *
+ * If non-strict mode is enabled, then DER rules are relaxed
+ * for indefinite constructs (violates DER but a little closer to BER).
+ * Non-strict mode should only be used by bs_ber.c
+ *
+ * Sections 8, 10 and 11 for DER encoding
+ */
+int
+cbs_get_any_asn1_element_internal(CBS *cbs, CBS *out, unsigned *out_tag,
+ size_t *out_header_len, int strict)
{
uint8_t tag, length_byte;
CBS header = *cbs;
CBS throwaway;
+ size_t len;
if (out == NULL)
out = &throwaway;
+ /*
+ * Get identifier octet and length octet. Only 1 octet for each
+ * is a CBS limitation.
+ */
if (!CBS_get_u8(&header, &tag) || !CBS_get_u8(&header, &length_byte))
return 0;
+ /* CBS limitation: long form tags are not supported. */
if ((tag & 0x1f) == 0x1f)
- /* Long form tags are not supported. */
return 0;
if (out_tag != NULL)
*out_tag = tag;
- size_t len;
if ((length_byte & 0x80) == 0) {
/* Short form length. */
len = ((size_t) length_byte) + 2;
const size_t num_bytes = length_byte & 0x7f;
uint32_t len32;
- if ((tag & CBS_ASN1_CONSTRUCTED) != 0 && num_bytes == 0) {
- /* indefinite length */
- if (out_header_len != NULL)
- *out_header_len = 2;
- return CBS_get_bytes(cbs, out, 2);
+ /* ASN.1 reserved value for future extensions */
+ if (num_bytes == 0x7f)
+ return 0;
+
+ /* Handle indefinite form length */
+ if (num_bytes == 0) {
+ /* DER encoding doesn't allow for indefinite form. */
+ if (strict) {
+ return 0;
+
+ } else {
+ if ((tag & CBS_ASN1_CONSTRUCTED) != 0 &&
+ num_bytes == 0) {
+ /* indefinite length */
+ if (out_header_len != NULL)
+ *out_header_len = 2;
+ return CBS_get_bytes(cbs, out, 2);
+ } else {
+ /* Primitive cannot use indefinite. */
+ return 0;
+ }
+ }
}
- if (num_bytes == 0 || num_bytes > 4)
+ /* CBS limitation. */
+ if (num_bytes > 4)
return 0;
if (!cbs_get_u(&header, &len32, num_bytes))
return 0;
+ /* DER has a minimum length octet requirements. */
if (len32 < 128)
- /* Length should have used short-form encoding. */
+ /* Should have used short form instead */
return 0;
if ((len32 >> ((num_bytes - 1) * 8)) == 0)
out = &throwaway;
if (!CBS_get_any_asn1_element(cbs, out, &tag, &header_len) ||
- tag != tag_value || (header_len > 0 &&
- /*
- * This ensures that the tag is either zero length or
- * indefinite-length.
- */
- CBS_len(out) == header_len &&
- CBS_data(out)[header_len - 1] == 0x80))
+ tag != tag_value)
return 0;
if (skip_header && !CBS_skip(out, header_len)) {
-/* $OpenBSD: bytestring.h,v 1.6 2015/06/13 09:02:45 doug Exp $ */
+/* $OpenBSD: bytestring.h,v 1.7 2015/06/15 07:35:49 doug Exp $ */
/*
* Copyright (c) 2014, Google Inc.
*
/*
* CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from
* |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to
- * the tag number and |*out_header_len| to the length of the ASN.1 header. If
- * the element has indefinite length then |*out| will only contain the
- * header. Each of |out|, |out_tag|, and |out_header_len| may be NULL to ignore
+ * the tag number and |*out_header_len| to the length of the ASN.1 header.
+ * Each of |out|, |out_tag|, and |out_header_len| may be NULL to ignore
* the value.
*
* Tag numbers greater than 30 are not supported (i.e. short form only).
int CBB_add_asn1_uint64(CBB *cbb, uint64_t value);
#ifdef LIBRESSL_INTERNAL
+/*
+ * CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from
+ * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to
+ * the tag number and |*out_header_len| to the length of the ASN.1 header. If
+ * strict mode is disabled and the element has indefinite length then |*out|
+ * will only contain the header. Each of |out|, |out_tag|, and
+ * |out_header_len| may be NULL to ignore the value.
+ *
+ * Tag numbers greater than 30 are not supported (i.e. short form only).
+ */
+int cbs_get_any_asn1_element_internal(CBS *cbs, CBS *out, unsigned *out_tag,
+ size_t *out_header_len, int strict);
+
/*
* CBS_asn1_ber_to_der reads an ASN.1 structure from |in|. If it finds
* indefinite-length elements then it attempts to convert the BER data to DER
-/* $OpenBSD: bs_ber.c,v 1.4 2015/04/29 02:11:09 doug Exp $ */
+/* $OpenBSD: bs_ber.c,v 1.5 2015/06/15 07:35:49 doug Exp $ */
/*
* Copyright (c) 2014, Google Inc.
*
*/
static const unsigned 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 *out_tag,
+ size_t *out_header_len)
+{
+ return cbs_get_any_asn1_element_internal(cbs, out,
+ out_tag, out_header_len, 0);
+}
+
/*
* cbs_find_ber walks an ASN.1 structure in |orig_in| and sets |*ber_found|
* depending on whether an indefinite length element was found. The value of
unsigned tag;
size_t header_len;
- if (!CBS_get_any_asn1_element(&in, &contents, &tag,
+ 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) {
*ber_found = 1;
/*
* is_eoc returns true if |header_len| and |contents|, as returned by
- * |CBS_get_any_asn1_element|, indicate an "end of contents" (EOC) value.
+ * |cbs_nonstrict_get_any_asn1_element|, indicate an "end of contents" (EOC)
+ * value.
*/
static char
is_eoc(size_t header_len, CBS *contents)
size_t header_len;
CBB *out_contents, out_contents_storage;
- if (!CBS_get_any_asn1_element(in, &contents, &tag, &header_len))
+ if (!cbs_nonstrict_get_any_asn1_element(in, &contents, &tag,
+ &header_len))
return 0;
out_contents = out;
CBS_init(&in_copy, CBS_data(in),
CBS_len(in));
- if (!CBS_get_any_asn1_element(&in_copy,
- &inner_contents, &inner_tag,
- &inner_header_len))
+ if (!cbs_nonstrict_get_any_asn1_element(
+ &in_copy, &inner_contents,
+ &inner_tag, &inner_header_len))
return 0;
if (CBS_len(&inner_contents) >
-/* $OpenBSD: bs_cbs.c,v 1.8 2015/06/13 08:46:00 doug Exp $ */
+/* $OpenBSD: bs_cbs.c,v 1.9 2015/06/15 07:35:49 doug Exp $ */
/*
* Copyright (c) 2014, Google Inc.
*
int
CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag,
size_t *out_header_len)
+{
+ return cbs_get_any_asn1_element_internal(cbs, out, out_tag,
+ out_header_len, 1);
+}
+
+/*
+ * Review X.690 for details on ASN.1 DER encoding.
+ *
+ * If non-strict mode is enabled, then DER rules are relaxed
+ * for indefinite constructs (violates DER but a little closer to BER).
+ * Non-strict mode should only be used by bs_ber.c
+ *
+ * Sections 8, 10 and 11 for DER encoding
+ */
+int
+cbs_get_any_asn1_element_internal(CBS *cbs, CBS *out, unsigned *out_tag,
+ size_t *out_header_len, int strict)
{
uint8_t tag, length_byte;
CBS header = *cbs;
CBS throwaway;
+ size_t len;
if (out == NULL)
out = &throwaway;
+ /*
+ * Get identifier octet and length octet. Only 1 octet for each
+ * is a CBS limitation.
+ */
if (!CBS_get_u8(&header, &tag) || !CBS_get_u8(&header, &length_byte))
return 0;
+ /* CBS limitation: long form tags are not supported. */
if ((tag & 0x1f) == 0x1f)
- /* Long form tags are not supported. */
return 0;
if (out_tag != NULL)
*out_tag = tag;
- size_t len;
if ((length_byte & 0x80) == 0) {
/* Short form length. */
len = ((size_t) length_byte) + 2;
const size_t num_bytes = length_byte & 0x7f;
uint32_t len32;
- if ((tag & CBS_ASN1_CONSTRUCTED) != 0 && num_bytes == 0) {
- /* indefinite length */
- if (out_header_len != NULL)
- *out_header_len = 2;
- return CBS_get_bytes(cbs, out, 2);
+ /* ASN.1 reserved value for future extensions */
+ if (num_bytes == 0x7f)
+ return 0;
+
+ /* Handle indefinite form length */
+ if (num_bytes == 0) {
+ /* DER encoding doesn't allow for indefinite form. */
+ if (strict) {
+ return 0;
+
+ } else {
+ if ((tag & CBS_ASN1_CONSTRUCTED) != 0 &&
+ num_bytes == 0) {
+ /* indefinite length */
+ if (out_header_len != NULL)
+ *out_header_len = 2;
+ return CBS_get_bytes(cbs, out, 2);
+ } else {
+ /* Primitive cannot use indefinite. */
+ return 0;
+ }
+ }
}
- if (num_bytes == 0 || num_bytes > 4)
+ /* CBS limitation. */
+ if (num_bytes > 4)
return 0;
if (!cbs_get_u(&header, &len32, num_bytes))
return 0;
+ /* DER has a minimum length octet requirements. */
if (len32 < 128)
- /* Length should have used short-form encoding. */
+ /* Should have used short form instead */
return 0;
if ((len32 >> ((num_bytes - 1) * 8)) == 0)
out = &throwaway;
if (!CBS_get_any_asn1_element(cbs, out, &tag, &header_len) ||
- tag != tag_value || (header_len > 0 &&
- /*
- * This ensures that the tag is either zero length or
- * indefinite-length.
- */
- CBS_len(out) == header_len &&
- CBS_data(out)[header_len - 1] == 0x80))
+ tag != tag_value)
return 0;
if (skip_header && !CBS_skip(out, header_len)) {
-/* $OpenBSD: bytestring.h,v 1.6 2015/06/13 09:02:45 doug Exp $ */
+/* $OpenBSD: bytestring.h,v 1.7 2015/06/15 07:35:49 doug Exp $ */
/*
* Copyright (c) 2014, Google Inc.
*
/*
* CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from
* |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to
- * the tag number and |*out_header_len| to the length of the ASN.1 header. If
- * the element has indefinite length then |*out| will only contain the
- * header. Each of |out|, |out_tag|, and |out_header_len| may be NULL to ignore
+ * the tag number and |*out_header_len| to the length of the ASN.1 header.
+ * Each of |out|, |out_tag|, and |out_header_len| may be NULL to ignore
* the value.
*
* Tag numbers greater than 30 are not supported (i.e. short form only).
int CBB_add_asn1_uint64(CBB *cbb, uint64_t value);
#ifdef LIBRESSL_INTERNAL
+/*
+ * CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from
+ * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to
+ * the tag number and |*out_header_len| to the length of the ASN.1 header. If
+ * strict mode is disabled and the element has indefinite length then |*out|
+ * will only contain the header. Each of |out|, |out_tag|, and
+ * |out_header_len| may be NULL to ignore the value.
+ *
+ * Tag numbers greater than 30 are not supported (i.e. short form only).
+ */
+int cbs_get_any_asn1_element_internal(CBS *cbs, CBS *out, unsigned *out_tag,
+ size_t *out_header_len, int strict);
+
/*
* CBS_asn1_ber_to_der reads an ASN.1 structure from |in|. If it finds
* indefinite-length elements then it attempts to convert the BER data to DER
projects / openbsd / commitdiff