| /* 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/buf.h> |
| #include <openssl/mem.h> |
| #include <openssl/bytestring.h> |
| |
| #include <assert.h> |
| #include <string.h> |
| |
| #include "internal.h" |
| |
| |
| void CBS_init(CBS *cbs, const uint8_t *data, size_t len) { |
| cbs->data = data; |
| cbs->len = len; |
| } |
| |
| static int cbs_get(CBS *cbs, const uint8_t **p, size_t n) { |
| if (cbs->len < n) { |
| return 0; |
| } |
| |
| *p = cbs->data; |
| cbs->data += n; |
| cbs->len -= n; |
| return 1; |
| } |
| |
| int CBS_skip(CBS *cbs, size_t len) { |
| const uint8_t *dummy; |
| return cbs_get(cbs, &dummy, len); |
| } |
| |
| const uint8_t *CBS_data(const CBS *cbs) { |
| return cbs->data; |
| } |
| |
| size_t CBS_len(const CBS *cbs) { |
| return cbs->len; |
| } |
| |
| int CBS_stow(const CBS *cbs, uint8_t **out_ptr, size_t *out_len) { |
| OPENSSL_free(*out_ptr); |
| *out_ptr = NULL; |
| *out_len = 0; |
| |
| if (cbs->len == 0) { |
| return 1; |
| } |
| *out_ptr = BUF_memdup(cbs->data, cbs->len); |
| if (*out_ptr == NULL) { |
| return 0; |
| } |
| *out_len = cbs->len; |
| return 1; |
| } |
| |
| int CBS_strdup(const CBS *cbs, char **out_ptr) { |
| if (*out_ptr != NULL) { |
| OPENSSL_free(*out_ptr); |
| } |
| *out_ptr = BUF_strndup((const char*)cbs->data, cbs->len); |
| return (*out_ptr != NULL); |
| } |
| |
| int CBS_contains_zero_byte(const CBS *cbs) { |
| return memchr(cbs->data, 0, cbs->len) != NULL; |
| } |
| |
| int CBS_mem_equal(const CBS *cbs, const uint8_t *data, size_t len) { |
| if (len != cbs->len) { |
| return 0; |
| } |
| return CRYPTO_memcmp(cbs->data, data, len) == 0; |
| } |
| |
| static int cbs_get_u(CBS *cbs, uint32_t *out, size_t len) { |
| uint32_t result = 0; |
| const uint8_t *data; |
| |
| if (!cbs_get(cbs, &data, len)) { |
| return 0; |
| } |
| for (size_t i = 0; i < len; i++) { |
| result <<= 8; |
| result |= data[i]; |
| } |
| *out = result; |
| return 1; |
| } |
| |
| int CBS_get_u8(CBS *cbs, uint8_t *out) { |
| const uint8_t *v; |
| if (!cbs_get(cbs, &v, 1)) { |
| return 0; |
| } |
| *out = *v; |
| return 1; |
| } |
| |
| int CBS_get_u16(CBS *cbs, uint16_t *out) { |
| uint32_t v; |
| if (!cbs_get_u(cbs, &v, 2)) { |
| return 0; |
| } |
| *out = v; |
| return 1; |
| } |
| |
| int CBS_get_u24(CBS *cbs, uint32_t *out) { |
| return cbs_get_u(cbs, out, 3); |
| } |
| |
| int CBS_get_u32(CBS *cbs, uint32_t *out) { |
| return cbs_get_u(cbs, out, 4); |
| } |
| |
| int CBS_get_last_u8(CBS *cbs, uint8_t *out) { |
| if (cbs->len == 0) { |
| return 0; |
| } |
| *out = cbs->data[cbs->len - 1]; |
| cbs->len--; |
| return 1; |
| } |
| |
| int CBS_get_bytes(CBS *cbs, CBS *out, size_t len) { |
| const uint8_t *v; |
| if (!cbs_get(cbs, &v, len)) { |
| return 0; |
| } |
| CBS_init(out, v, len); |
| return 1; |
| } |
| |
| int CBS_copy_bytes(CBS *cbs, uint8_t *out, size_t len) { |
| const uint8_t *v; |
| if (!cbs_get(cbs, &v, len)) { |
| return 0; |
| } |
| memcpy(out, v, len); |
| return 1; |
| } |
| |
| static int cbs_get_length_prefixed(CBS *cbs, CBS *out, size_t len_len) { |
| uint32_t len; |
| if (!cbs_get_u(cbs, &len, len_len)) { |
| return 0; |
| } |
| return CBS_get_bytes(cbs, out, len); |
| } |
| |
| int CBS_get_u8_length_prefixed(CBS *cbs, CBS *out) { |
| return cbs_get_length_prefixed(cbs, out, 1); |
| } |
| |
| int CBS_get_u16_length_prefixed(CBS *cbs, CBS *out) { |
| return cbs_get_length_prefixed(cbs, out, 2); |
| } |
| |
| int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out) { |
| return cbs_get_length_prefixed(cbs, out, 3); |
| } |
| |
| static int cbs_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag, |
| size_t *out_header_len, int ber_ok) { |
| uint8_t tag, length_byte; |
| CBS header = *cbs; |
| CBS throwaway; |
| |
| if (out == NULL) { |
| out = &throwaway; |
| } |
| |
| if (!CBS_get_u8(&header, &tag) || |
| !CBS_get_u8(&header, &length_byte)) { |
| return 0; |
| } |
| |
| /* ITU-T X.690 section 8.1.2.3 specifies the format for identifiers with a tag |
| * number no greater than 30. |
| * |
| * If the number portion is 31 (0x1f, the largest value that fits in the |
| * allotted bits), then the tag is more than one byte long and the |
| * continuation bytes contain the tag number. This parser only supports tag |
| * numbers less than 31 (and thus single-byte tags). */ |
| if ((tag & 0x1f) == 0x1f) { |
| return 0; |
| } |
| |
| if (out_tag != NULL) { |
| *out_tag = tag; |
| } |
| |
| size_t len; |
| /* The format for the length encoding is specified in ITU-T X.690 section |
| * 8.1.3. */ |
| if ((length_byte & 0x80) == 0) { |
| /* Short form length. */ |
| len = ((size_t) length_byte) + 2; |
| if (out_header_len != NULL) { |
| *out_header_len = 2; |
| } |
| } else { |
| /* The high bit indicate that this is the long form, while the next 7 bits |
| * encode the number of subsequent octets used to encode the length (ITU-T |
| * X.690 clause 8.1.3.5.b). */ |
| const size_t num_bytes = length_byte & 0x7f; |
| uint32_t len32; |
| |
| if (ber_ok && (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); |
| } |
| |
| /* ITU-T X.690 clause 8.1.3.5.c specifies that the value 0xff shall not be |
| * used as the first byte of the length. If this parser encounters that |
| * value, num_bytes will be parsed as 127, which will fail the check below. |
| */ |
| if (num_bytes == 0 || num_bytes > 4) { |
| return 0; |
| } |
| if (!cbs_get_u(&header, &len32, num_bytes)) { |
| return 0; |
| } |
| /* ITU-T X.690 section 10.1 (DER length forms) requires encoding the length |
| * with the minimum number of octets. */ |
| if (len32 < 128) { |
| /* Length should have used short-form encoding. */ |
| return 0; |
| } |
| if ((len32 >> ((num_bytes-1)*8)) == 0) { |
| /* Length should have been at least one byte shorter. */ |
| return 0; |
| } |
| len = len32; |
| if (len + 2 + num_bytes < len) { |
| /* Overflow. */ |
| return 0; |
| } |
| len += 2 + num_bytes; |
| if (out_header_len != NULL) { |
| *out_header_len = 2 + num_bytes; |
| } |
| } |
| |
| return CBS_get_bytes(cbs, out, len); |
| } |
| |
| int CBS_get_any_asn1(CBS *cbs, CBS *out, unsigned *out_tag) { |
| size_t header_len; |
| if (!CBS_get_any_asn1_element(cbs, out, out_tag, &header_len)) { |
| return 0; |
| } |
| |
| if (!CBS_skip(out, header_len)) { |
| assert(0); |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| int CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag, |
| size_t *out_header_len) { |
| return cbs_get_any_asn1_element(cbs, out, out_tag, out_header_len, |
| 0 /* DER only */); |
| } |
| |
| int CBS_get_any_ber_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag, |
| size_t *out_header_len) { |
| return cbs_get_any_asn1_element(cbs, out, out_tag, out_header_len, |
| 1 /* BER allowed */); |
| } |
| |
| static int cbs_get_asn1(CBS *cbs, CBS *out, unsigned tag_value, |
| int skip_header) { |
| size_t header_len; |
| unsigned tag; |
| CBS throwaway; |
| |
| if (out == NULL) { |
| out = &throwaway; |
| } |
| |
| if (!CBS_get_any_asn1_element(cbs, out, &tag, &header_len) || |
| tag != tag_value) { |
| return 0; |
| } |
| |
| if (skip_header && !CBS_skip(out, header_len)) { |
| assert(0); |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| int CBS_get_asn1(CBS *cbs, CBS *out, unsigned tag_value) { |
| return cbs_get_asn1(cbs, out, tag_value, 1 /* skip header */); |
| } |
| |
| int CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned tag_value) { |
| return cbs_get_asn1(cbs, out, tag_value, 0 /* include header */); |
| } |
| |
| int CBS_peek_asn1_tag(const CBS *cbs, unsigned tag_value) { |
| if (CBS_len(cbs) < 1) { |
| return 0; |
| } |
| return CBS_data(cbs)[0] == tag_value; |
| } |
| |
| int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out) { |
| CBS bytes; |
| const uint8_t *data; |
| size_t i, len; |
| |
| if (!CBS_get_asn1(cbs, &bytes, CBS_ASN1_INTEGER)) { |
| return 0; |
| } |
| |
| *out = 0; |
| data = CBS_data(&bytes); |
| len = CBS_len(&bytes); |
| |
| if (len == 0) { |
| /* An INTEGER is encoded with at least one octet. */ |
| return 0; |
| } |
| |
| if ((data[0] & 0x80) != 0) { |
| /* Negative number. */ |
| return 0; |
| } |
| |
| if (data[0] == 0 && len > 1 && (data[1] & 0x80) == 0) { |
| /* Extra leading zeros. */ |
| return 0; |
| } |
| |
| for (i = 0; i < len; i++) { |
| if ((*out >> 56) != 0) { |
| /* Too large to represent as a uint64_t. */ |
| return 0; |
| } |
| *out <<= 8; |
| *out |= data[i]; |
| } |
| |
| return 1; |
| } |
| |
| int CBS_get_optional_asn1(CBS *cbs, CBS *out, int *out_present, unsigned tag) { |
| int present = 0; |
| |
| if (CBS_peek_asn1_tag(cbs, tag)) { |
| if (!CBS_get_asn1(cbs, out, tag)) { |
| return 0; |
| } |
| present = 1; |
| } |
| |
| if (out_present != NULL) { |
| *out_present = present; |
| } |
| |
| return 1; |
| } |
| |
| int CBS_get_optional_asn1_octet_string(CBS *cbs, CBS *out, int *out_present, |
| unsigned tag) { |
| CBS child; |
| int present; |
| if (!CBS_get_optional_asn1(cbs, &child, &present, tag)) { |
| return 0; |
| } |
| if (present) { |
| if (!CBS_get_asn1(&child, out, CBS_ASN1_OCTETSTRING) || |
| CBS_len(&child) != 0) { |
| return 0; |
| } |
| } else { |
| CBS_init(out, NULL, 0); |
| } |
| if (out_present) { |
| *out_present = present; |
| } |
| return 1; |
| } |
| |
| int CBS_get_optional_asn1_uint64(CBS *cbs, uint64_t *out, unsigned tag, |
| uint64_t default_value) { |
| CBS child; |
| int present; |
| if (!CBS_get_optional_asn1(cbs, &child, &present, tag)) { |
| return 0; |
| } |
| if (present) { |
| if (!CBS_get_asn1_uint64(&child, out) || |
| CBS_len(&child) != 0) { |
| return 0; |
| } |
| } else { |
| *out = default_value; |
| } |
| return 1; |
| } |
| |
| int CBS_get_optional_asn1_bool(CBS *cbs, int *out, unsigned tag, |
| int default_value) { |
| CBS child, child2; |
| int present; |
| if (!CBS_get_optional_asn1(cbs, &child, &present, tag)) { |
| return 0; |
| } |
| if (present) { |
| uint8_t boolean; |
| |
| if (!CBS_get_asn1(&child, &child2, CBS_ASN1_BOOLEAN) || |
| CBS_len(&child2) != 1 || |
| CBS_len(&child) != 0) { |
| return 0; |
| } |
| |
| boolean = CBS_data(&child2)[0]; |
| if (boolean == 0) { |
| *out = 0; |
| } else if (boolean == 0xff) { |
| *out = 1; |
| } else { |
| return 0; |
| } |
| } else { |
| *out = default_value; |
| } |
| return 1; |
| } |
| |
| int CBS_is_valid_asn1_bitstring(const CBS *cbs) { |
| CBS in = *cbs; |
| uint8_t num_unused_bits; |
| if (!CBS_get_u8(&in, &num_unused_bits) || |
| num_unused_bits > 7) { |
| return 0; |
| } |
| |
| if (num_unused_bits == 0) { |
| return 1; |
| } |
| |
| /* All num_unused_bits bits must exist and be zeros. */ |
| uint8_t last; |
| if (!CBS_get_last_u8(&in, &last) || |
| (last & ((1 << num_unused_bits) - 1)) != 0) { |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| int CBS_asn1_bitstring_has_bit(const CBS *cbs, unsigned bit) { |
| if (!CBS_is_valid_asn1_bitstring(cbs)) { |
| return 0; |
| } |
| |
| const unsigned byte_num = (bit >> 3) + 1; |
| const unsigned bit_num = 7 - (bit & 7); |
| |
| /* Unused bits are zero, and this function does not distinguish between |
| * missing and unset bits. Thus it is sufficient to do a byte-level length |
| * check. */ |
| return byte_num < CBS_len(cbs) && |
| (CBS_data(cbs)[byte_num] & (1 << bit_num)) != 0; |
| } |