| /* 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 <openssl/bytestring.h> |
| |
| #include <assert.h> |
| #include <string.h> |
| |
| #include "internal.h" |
| #include "../internal.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 kMaxDepth = 2048; |
| |
| /* is_string_type returns one if |tag| is a string type and zero otherwise. It |
| * ignores the constructed bit. */ |
| static int is_string_type(unsigned tag) { |
| if ((tag & 0xc0) != 0) { |
| return 0; |
| } |
| switch (tag & 0x1f) { |
| case CBS_ASN1_BITSTRING: |
| case CBS_ASN1_OCTETSTRING: |
| case CBS_ASN1_UTF8STRING: |
| case CBS_ASN1_NUMERICSTRING: |
| case CBS_ASN1_PRINTABLESTRING: |
| case CBS_ASN1_T61STRING: |
| case CBS_ASN1_VIDEOTEXSTRING: |
| case CBS_ASN1_IA5STRING: |
| case CBS_ASN1_GRAPHICSTRING: |
| case CBS_ASN1_VISIBLESTRING: |
| case CBS_ASN1_GENERALSTRING: |
| case CBS_ASN1_UNIVERSALSTRING: |
| case CBS_ASN1_BMPSTRING: |
| return 1; |
| default: |
| return 0; |
| } |
| } |
| |
| /* cbs_find_ber walks an ASN.1 structure in |orig_in| and sets |*ber_found| |
| * depending on whether an indefinite length element or constructed string was |
| * found. The value of |orig_in| is not changed. It returns one on success (i.e. |
| * |*ber_found| was set) and zero on error. */ |
| static int cbs_find_ber(const CBS *orig_in, char *ber_found, unsigned depth) { |
| CBS in; |
| |
| if (depth > kMaxDepth) { |
| return 0; |
| } |
| |
| CBS_init(&in, CBS_data(orig_in), CBS_len(orig_in)); |
| *ber_found = 0; |
| |
| while (CBS_len(&in) > 0) { |
| CBS contents; |
| unsigned tag; |
| size_t header_len; |
| |
| if (!CBS_get_any_ber_asn1_element(&in, &contents, &tag, &header_len)) { |
| return 0; |
| } |
| if (CBS_len(&contents) == header_len && |
| header_len > 0 && |
| CBS_data(&contents)[header_len-1] == 0x80) { |
| /* Found an indefinite-length element. */ |
| *ber_found = 1; |
| return 1; |
| } |
| if (tag & CBS_ASN1_CONSTRUCTED) { |
| if (is_string_type(tag)) { |
| /* Constructed strings are only legal in BER and require conversion. */ |
| *ber_found = 1; |
| return 1; |
| } |
| if (!CBS_skip(&contents, header_len) || |
| !cbs_find_ber(&contents, ber_found, depth + 1)) { |
| return 0; |
| } |
| } |
| } |
| |
| return 1; |
| } |
| |
| /* is_eoc returns true if |header_len| and |contents|, as returned by |
| * |CBS_get_any_ber_asn1_element|, indicate an "end of contents" (EOC) value. */ |
| static char is_eoc(size_t header_len, CBS *contents) { |
| return header_len == 2 && CBS_len(contents) == 2 && |
| OPENSSL_memcmp(CBS_data(contents), "\x00\x00", 2) == 0; |
| } |
| |
| /* cbs_convert_ber reads BER data from |in| and writes DER data to |out|. If |
| * |string_tag| is non-zero, then all elements must match |string_tag| up to the |
| * constructed bit and primitive element bodies are written to |out| without |
| * element headers. This is used when concatenating the fragments of a |
| * constructed string. 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_ber(CBS *in, CBB *out, unsigned string_tag, |
| char looking_for_eoc, unsigned depth) { |
| assert(!(string_tag & CBS_ASN1_CONSTRUCTED)); |
| |
| if (depth > kMaxDepth) { |
| return 0; |
| } |
| |
| while (CBS_len(in) > 0) { |
| CBS contents; |
| unsigned tag, child_string_tag = string_tag; |
| size_t header_len; |
| CBB *out_contents, out_contents_storage; |
| |
| if (!CBS_get_any_ber_asn1_element(in, &contents, &tag, &header_len)) { |
| return 0; |
| } |
| |
| if (is_eoc(header_len, &contents)) { |
| return looking_for_eoc; |
| } |
| |
| if (string_tag != 0) { |
| /* This is part of a constructed string. All elements must match |
| * |string_tag| up to the constructed bit and get appended to |out| |
| * without a child element. */ |
| if ((tag & ~CBS_ASN1_CONSTRUCTED) != string_tag) { |
| return 0; |
| } |
| out_contents = out; |
| } else { |
| unsigned out_tag = tag; |
| if ((tag & CBS_ASN1_CONSTRUCTED) && is_string_type(tag)) { |
| /* If a constructed string, clear the constructed bit and inform |
| * children to concatenate bodies. */ |
| out_tag &= ~CBS_ASN1_CONSTRUCTED; |
| child_string_tag = out_tag; |
| } |
| if (!CBB_add_asn1(out, &out_contents_storage, out_tag)) { |
| return 0; |
| } |
| out_contents = &out_contents_storage; |
| } |
| |
| if (CBS_len(&contents) == header_len && header_len > 0 && |
| CBS_data(&contents)[header_len - 1] == 0x80) { |
| /* This is an indefinite length element. */ |
| if (!cbs_convert_ber(in, out_contents, child_string_tag, |
| 1 /* looking for eoc */, depth + 1) || |
| !CBB_flush(out)) { |
| return 0; |
| } |
| continue; |
| } |
| |
| if (!CBS_skip(&contents, header_len)) { |
| return 0; |
| } |
| |
| if (tag & CBS_ASN1_CONSTRUCTED) { |
| /* Recurse into children. */ |
| if (!cbs_convert_ber(&contents, out_contents, child_string_tag, |
| 0 /* not looking for eoc */, depth + 1)) { |
| return 0; |
| } |
| } else { |
| /* Copy primitive contents as-is. */ |
| if (!CBB_add_bytes(out_contents, CBS_data(&contents), |
| CBS_len(&contents))) { |
| return 0; |
| } |
| } |
| |
| if (!CBB_flush(out)) { |
| return 0; |
| } |
| } |
| |
| return looking_for_eoc == 0; |
| } |
| |
| int CBS_asn1_ber_to_der(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_ber(in, &conversion_needed, 0)) { |
| return 0; |
| } |
| |
| if (!conversion_needed) { |
| *out = NULL; |
| *out_len = 0; |
| return 1; |
| } |
| |
| if (!CBB_init(&cbb, CBS_len(in)) || |
| !cbs_convert_ber(in, &cbb, 0, 0, 0) || |
| !CBB_finish(&cbb, out, out_len)) { |
| CBB_cleanup(&cbb); |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| int CBS_get_asn1_implicit_string(CBS *in, CBS *out, uint8_t **out_storage, |
| unsigned outer_tag, unsigned inner_tag) { |
| assert(!(outer_tag & CBS_ASN1_CONSTRUCTED)); |
| assert(!(inner_tag & CBS_ASN1_CONSTRUCTED)); |
| assert(is_string_type(inner_tag)); |
| |
| if (CBS_peek_asn1_tag(in, outer_tag)) { |
| /* Normal implicitly-tagged string. */ |
| *out_storage = NULL; |
| return CBS_get_asn1(in, out, outer_tag); |
| } |
| |
| /* Otherwise, try to parse an implicitly-tagged constructed string. |
| * |CBS_asn1_ber_to_der| is assumed to have run, so only allow one level deep |
| * of nesting. */ |
| CBB result; |
| CBS child; |
| if (!CBB_init(&result, CBS_len(in)) || |
| !CBS_get_asn1(in, &child, outer_tag | CBS_ASN1_CONSTRUCTED)) { |
| goto err; |
| } |
| |
| while (CBS_len(&child) > 0) { |
| CBS chunk; |
| if (!CBS_get_asn1(&child, &chunk, inner_tag) || |
| !CBB_add_bytes(&result, CBS_data(&chunk), CBS_len(&chunk))) { |
| goto err; |
| } |
| } |
| |
| uint8_t *data; |
| size_t len; |
| if (!CBB_finish(&result, &data, &len)) { |
| goto err; |
| } |
| |
| CBS_init(out, data, len); |
| *out_storage = data; |
| return 1; |
| |
| err: |
| CBB_cleanup(&result); |
| return 0; |
| } |