blob: 25d087ce577074a21cd0e84c55590df5a5d9d74b [file] [log] [blame]
/* 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 <limits.h>
#include <string.h>
#include <openssl/mem.h>
#include "../internal.h"
void CBB_zero(CBB *cbb) {
OPENSSL_memset(cbb, 0, sizeof(CBB));
}
static int cbb_init(CBB *cbb, uint8_t *buf, size_t cap) {
// This assumes that |cbb| has already been zeroed.
struct cbb_buffer_st *base;
base = OPENSSL_malloc(sizeof(struct cbb_buffer_st));
if (base == NULL) {
return 0;
}
base->buf = buf;
base->len = 0;
base->cap = cap;
base->can_resize = 1;
base->error = 0;
cbb->base = base;
cbb->is_child = 0;
return 1;
}
int CBB_init(CBB *cbb, size_t initial_capacity) {
CBB_zero(cbb);
uint8_t *buf = OPENSSL_malloc(initial_capacity);
if (initial_capacity > 0 && buf == NULL) {
return 0;
}
if (!cbb_init(cbb, buf, initial_capacity)) {
OPENSSL_free(buf);
return 0;
}
return 1;
}
int CBB_init_fixed(CBB *cbb, uint8_t *buf, size_t len) {
CBB_zero(cbb);
if (!cbb_init(cbb, buf, len)) {
return 0;
}
cbb->base->can_resize = 0;
return 1;
}
void CBB_cleanup(CBB *cbb) {
// Child |CBB|s are non-owning. They are implicitly discarded and should not
// be used with |CBB_cleanup| or |ScopedCBB|.
assert(!cbb->is_child);
if (cbb->is_child) {
return;
}
if (cbb->base) {
if (cbb->base->can_resize) {
OPENSSL_free(cbb->base->buf);
}
OPENSSL_free(cbb->base);
}
cbb->base = NULL;
}
static int cbb_buffer_reserve(struct cbb_buffer_st *base, uint8_t **out,
size_t len) {
size_t newlen;
if (base == NULL) {
return 0;
}
newlen = base->len + len;
if (newlen < base->len) {
// Overflow
goto err;
}
if (newlen > base->cap) {
size_t newcap = base->cap * 2;
uint8_t *newbuf;
if (!base->can_resize) {
goto err;
}
if (newcap < base->cap || newcap < newlen) {
newcap = newlen;
}
newbuf = OPENSSL_realloc(base->buf, newcap);
if (newbuf == NULL) {
goto err;
}
base->buf = newbuf;
base->cap = newcap;
}
if (out) {
*out = base->buf + base->len;
}
return 1;
err:
base->error = 1;
return 0;
}
static int cbb_buffer_add(struct cbb_buffer_st *base, uint8_t **out,
size_t len) {
if (!cbb_buffer_reserve(base, out, len)) {
return 0;
}
// This will not overflow or |cbb_buffer_reserve| would have failed.
base->len += len;
return 1;
}
static int cbb_buffer_add_u(struct cbb_buffer_st *base, uint64_t v,
size_t len_len) {
if (len_len == 0) {
return 1;
}
uint8_t *buf;
if (!cbb_buffer_add(base, &buf, len_len)) {
return 0;
}
for (size_t i = len_len - 1; i < len_len; i--) {
buf[i] = v;
v >>= 8;
}
if (v != 0) {
base->error = 1;
return 0;
}
return 1;
}
int CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len) {
if (cbb->is_child) {
return 0;
}
if (!CBB_flush(cbb)) {
return 0;
}
if (cbb->base->can_resize && (out_data == NULL || out_len == NULL)) {
// |out_data| and |out_len| can only be NULL if the CBB is fixed.
return 0;
}
if (out_data != NULL) {
*out_data = cbb->base->buf;
}
if (out_len != NULL) {
*out_len = cbb->base->len;
}
cbb->base->buf = NULL;
CBB_cleanup(cbb);
return 1;
}
// CBB_flush recurses and then writes out any pending length prefix. The
// current length of the underlying base is taken to be the length of the
// length-prefixed data.
int CBB_flush(CBB *cbb) {
size_t child_start, i, len;
// If |cbb->base| has hit an error, the buffer is in an undefined state, so
// fail all following calls. In particular, |cbb->child| may point to invalid
// memory.
if (cbb->base == NULL || cbb->base->error) {
return 0;
}
if (cbb->child == NULL || cbb->child->pending_len_len == 0) {
return 1;
}
child_start = cbb->child->offset + cbb->child->pending_len_len;
if (!CBB_flush(cbb->child) ||
child_start < cbb->child->offset ||
cbb->base->len < child_start) {
goto err;
}
len = cbb->base->len - child_start;
if (cbb->child->pending_is_asn1) {
// For ASN.1 we assume that we'll only need a single byte for the length.
// If that turned out to be incorrect, we have to move the contents along
// in order to make space.
uint8_t len_len;
uint8_t initial_length_byte;
assert (cbb->child->pending_len_len == 1);
if (len > 0xfffffffe) {
// Too large.
goto err;
} else if (len > 0xffffff) {
len_len = 5;
initial_length_byte = 0x80 | 4;
} else if (len > 0xffff) {
len_len = 4;
initial_length_byte = 0x80 | 3;
} else if (len > 0xff) {
len_len = 3;
initial_length_byte = 0x80 | 2;
} else if (len > 0x7f) {
len_len = 2;
initial_length_byte = 0x80 | 1;
} else {
len_len = 1;
initial_length_byte = (uint8_t)len;
len = 0;
}
if (len_len != 1) {
// We need to move the contents along in order to make space.
size_t extra_bytes = len_len - 1;
if (!cbb_buffer_add(cbb->base, NULL, extra_bytes)) {
goto err;
}
OPENSSL_memmove(cbb->base->buf + child_start + extra_bytes,
cbb->base->buf + child_start, len);
}
cbb->base->buf[cbb->child->offset++] = initial_length_byte;
cbb->child->pending_len_len = len_len - 1;
}
for (i = cbb->child->pending_len_len - 1; i < cbb->child->pending_len_len;
i--) {
cbb->base->buf[cbb->child->offset + i] = (uint8_t)len;
len >>= 8;
}
if (len != 0) {
goto err;
}
cbb->child->base = NULL;
cbb->child = NULL;
return 1;
err:
cbb->base->error = 1;
return 0;
}
const uint8_t *CBB_data(const CBB *cbb) {
assert(cbb->child == NULL);
return cbb->base->buf + cbb->offset + cbb->pending_len_len;
}
size_t CBB_len(const CBB *cbb) {
assert(cbb->child == NULL);
assert(cbb->offset + cbb->pending_len_len <= cbb->base->len);
return cbb->base->len - cbb->offset - cbb->pending_len_len;
}
static int cbb_add_length_prefixed(CBB *cbb, CBB *out_contents,
uint8_t len_len) {
uint8_t *prefix_bytes;
if (!CBB_flush(cbb)) {
return 0;
}
size_t offset = cbb->base->len;
if (!cbb_buffer_add(cbb->base, &prefix_bytes, len_len)) {
return 0;
}
OPENSSL_memset(prefix_bytes, 0, len_len);
OPENSSL_memset(out_contents, 0, sizeof(CBB));
out_contents->base = cbb->base;
out_contents->is_child = 1;
cbb->child = out_contents;
cbb->child->offset = offset;
cbb->child->pending_len_len = len_len;
cbb->child->pending_is_asn1 = 0;
return 1;
}
int CBB_add_u8_length_prefixed(CBB *cbb, CBB *out_contents) {
return cbb_add_length_prefixed(cbb, out_contents, 1);
}
int CBB_add_u16_length_prefixed(CBB *cbb, CBB *out_contents) {
return cbb_add_length_prefixed(cbb, out_contents, 2);
}
int CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents) {
return cbb_add_length_prefixed(cbb, out_contents, 3);
}
// add_base128_integer encodes |v| as a big-endian base-128 integer where the
// high bit of each byte indicates where there is more data. This is the
// encoding used in DER for both high tag number form and OID components.
static int add_base128_integer(CBB *cbb, uint64_t v) {
unsigned len_len = 0;
uint64_t copy = v;
while (copy > 0) {
len_len++;
copy >>= 7;
}
if (len_len == 0) {
len_len = 1; // Zero is encoded with one byte.
}
for (unsigned i = len_len - 1; i < len_len; i--) {
uint8_t byte = (v >> (7 * i)) & 0x7f;
if (i != 0) {
// The high bit denotes whether there is more data.
byte |= 0x80;
}
if (!CBB_add_u8(cbb, byte)) {
return 0;
}
}
return 1;
}
int CBB_add_asn1(CBB *cbb, CBB *out_contents, unsigned tag) {
if (!CBB_flush(cbb)) {
return 0;
}
// Split the tag into leading bits and tag number.
uint8_t tag_bits = (tag >> CBS_ASN1_TAG_SHIFT) & 0xe0;
unsigned tag_number = tag & CBS_ASN1_TAG_NUMBER_MASK;
if (tag_number >= 0x1f) {
// Set all the bits in the tag number to signal high tag number form.
if (!CBB_add_u8(cbb, tag_bits | 0x1f) ||
!add_base128_integer(cbb, tag_number)) {
return 0;
}
} else if (!CBB_add_u8(cbb, tag_bits | tag_number)) {
return 0;
}
size_t offset = cbb->base->len;
if (!CBB_add_u8(cbb, 0)) {
return 0;
}
OPENSSL_memset(out_contents, 0, sizeof(CBB));
out_contents->base = cbb->base;
out_contents->is_child = 1;
cbb->child = out_contents;
cbb->child->offset = offset;
cbb->child->pending_len_len = 1;
cbb->child->pending_is_asn1 = 1;
return 1;
}
int CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len) {
uint8_t *dest;
if (!CBB_flush(cbb) ||
!cbb_buffer_add(cbb->base, &dest, len)) {
return 0;
}
OPENSSL_memcpy(dest, data, len);
return 1;
}
int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len) {
if (!CBB_flush(cbb) ||
!cbb_buffer_add(cbb->base, out_data, len)) {
return 0;
}
return 1;
}
int CBB_reserve(CBB *cbb, uint8_t **out_data, size_t len) {
if (!CBB_flush(cbb) ||
!cbb_buffer_reserve(cbb->base, out_data, len)) {
return 0;
}
return 1;
}
int CBB_did_write(CBB *cbb, size_t len) {
size_t newlen = cbb->base->len + len;
if (cbb->child != NULL ||
newlen < cbb->base->len ||
newlen > cbb->base->cap) {
return 0;
}
cbb->base->len = newlen;
return 1;
}
int CBB_add_u8(CBB *cbb, uint8_t value) {
if (!CBB_flush(cbb)) {
return 0;
}
return cbb_buffer_add_u(cbb->base, value, 1);
}
int CBB_add_u16(CBB *cbb, uint16_t value) {
if (!CBB_flush(cbb)) {
return 0;
}
return cbb_buffer_add_u(cbb->base, value, 2);
}
int CBB_add_u24(CBB *cbb, uint32_t value) {
if (!CBB_flush(cbb)) {
return 0;
}
return cbb_buffer_add_u(cbb->base, value, 3);
}
int CBB_add_u32(CBB *cbb, uint32_t value) {
if (!CBB_flush(cbb)) {
return 0;
}
return cbb_buffer_add_u(cbb->base, value, 4);
}
int CBB_add_u64(CBB *cbb, uint64_t value) {
if (!CBB_flush(cbb)) {
return 0;
}
return cbb_buffer_add_u(cbb->base, value, 8);
}
void CBB_discard_child(CBB *cbb) {
if (cbb->child == NULL) {
return;
}
cbb->base->len = cbb->child->offset;
cbb->child->base = NULL;
cbb->child = NULL;
}
int CBB_add_asn1_uint64(CBB *cbb, uint64_t value) {
CBB child;
int started = 0;
if (!CBB_add_asn1(cbb, &child, CBS_ASN1_INTEGER)) {
return 0;
}
for (size_t i = 0; i < 8; i++) {
uint8_t byte = (value >> 8*(7-i)) & 0xff;
if (!started) {
if (byte == 0) {
// Don't encode leading zeros.
continue;
}
// If the high bit is set, add a padding byte to make it
// unsigned.
if ((byte & 0x80) && !CBB_add_u8(&child, 0)) {
return 0;
}
started = 1;
}
if (!CBB_add_u8(&child, byte)) {
return 0;
}
}
// 0 is encoded as a single 0, not the empty string.
if (!started && !CBB_add_u8(&child, 0)) {
return 0;
}
return CBB_flush(cbb);
}
int CBB_add_asn1_octet_string(CBB *cbb, const uint8_t *data, size_t data_len) {
CBB child;
if (!CBB_add_asn1(cbb, &child, CBS_ASN1_OCTETSTRING) ||
!CBB_add_bytes(&child, data, data_len) ||
!CBB_flush(cbb)) {
return 0;
}
return 1;
}
int CBB_add_asn1_bool(CBB *cbb, int value) {
CBB child;
if (!CBB_add_asn1(cbb, &child, CBS_ASN1_BOOLEAN) ||
!CBB_add_u8(&child, value != 0 ? 0xff : 0) ||
!CBB_flush(cbb)) {
return 0;
}
return 1;
}
// parse_dotted_decimal parses one decimal component from |cbs|, where |cbs| is
// an OID literal, e.g., "1.2.840.113554.4.1.72585". It consumes both the
// component and the dot, so |cbs| may be passed into the function again for the
// next value.
static int parse_dotted_decimal(CBS *cbs, uint64_t *out) {
*out = 0;
int seen_digit = 0;
for (;;) {
// Valid terminators for a component are the end of the string or a
// non-terminal dot. If the string ends with a dot, this is not a valid OID
// string.
uint8_t u;
if (!CBS_get_u8(cbs, &u) ||
(u == '.' && CBS_len(cbs) > 0)) {
break;
}
if (u < '0' || u > '9' ||
// Forbid stray leading zeros.
(seen_digit && *out == 0) ||
// Check for overflow.
*out > UINT64_MAX / 10 ||
*out * 10 > UINT64_MAX - (u - '0')) {
return 0;
}
*out = *out * 10 + (u - '0');
seen_digit = 1;
}
// The empty string is not a legal OID component.
return seen_digit;
}
int CBB_add_asn1_oid_from_text(CBB *cbb, const char *text, size_t len) {
if (!CBB_flush(cbb)) {
return 0;
}
CBS cbs;
CBS_init(&cbs, (const uint8_t *)text, len);
// OIDs must have at least two components.
uint64_t a, b;
if (!parse_dotted_decimal(&cbs, &a) ||
!parse_dotted_decimal(&cbs, &b)) {
return 0;
}
// The first component is encoded as 40 * |a| + |b|. This assumes that |a| is
// 0, 1, or 2 and that, when it is 0 or 1, |b| is at most 39.
if (a > 2 ||
(a < 2 && b > 39) ||
b > UINT64_MAX - 80 ||
!add_base128_integer(cbb, 40u * a + b)) {
return 0;
}
// The remaining components are encoded unmodified.
while (CBS_len(&cbs) > 0) {
if (!parse_dotted_decimal(&cbs, &a) ||
!add_base128_integer(cbb, a)) {
return 0;
}
}
return 1;
}
static int compare_set_of_element(const void *a_ptr, const void *b_ptr) {
// See X.690, section 11.6 for the ordering. They are sorted in ascending
// order by their DER encoding.
const CBS *a = a_ptr, *b = b_ptr;
size_t a_len = CBS_len(a), b_len = CBS_len(b);
size_t min_len = a_len < b_len ? a_len : b_len;
int ret = OPENSSL_memcmp(CBS_data(a), CBS_data(b), min_len);
if (ret != 0) {
return ret;
}
if (a_len == b_len) {
return 0;
}
// If one is a prefix of the other, the shorter one sorts first. (This is not
// actually reachable. No DER encoding is a prefix of another DER encoding.)
return a_len < b_len ? -1 : 1;
}
int CBB_flush_asn1_set_of(CBB *cbb) {
if (!CBB_flush(cbb)) {
return 0;
}
CBS cbs;
size_t num_children = 0;
CBS_init(&cbs, CBB_data(cbb), CBB_len(cbb));
while (CBS_len(&cbs) != 0) {
if (!CBS_get_any_asn1_element(&cbs, NULL, NULL, NULL)) {
return 0;
}
num_children++;
}
if (num_children < 2) {
return 1; // Nothing to do. This is the common case for X.509.
}
if (num_children > ((size_t)-1) / sizeof(CBS)) {
return 0; // Overflow.
}
// Parse out the children and sort. We alias them into a copy of so they
// remain valid as we rewrite |cbb|.
int ret = 0;
size_t buf_len = CBB_len(cbb);
uint8_t *buf = OPENSSL_memdup(CBB_data(cbb), buf_len);
CBS *children = OPENSSL_malloc(num_children * sizeof(CBS));
if (buf == NULL || children == NULL) {
goto err;
}
CBS_init(&cbs, buf, buf_len);
for (size_t i = 0; i < num_children; i++) {
if (!CBS_get_any_asn1_element(&cbs, &children[i], NULL, NULL)) {
goto err;
}
}
qsort(children, num_children, sizeof(CBS), compare_set_of_element);
// Rewind |cbb| and write the contents back in the new order.
cbb->base->len = cbb->offset + cbb->pending_len_len;
for (size_t i = 0; i < num_children; i++) {
if (!CBB_add_bytes(cbb, CBS_data(&children[i]), CBS_len(&children[i]))) {
goto err;
}
}
assert(CBB_len(cbb) == buf_len);
ret = 1;
err:
OPENSSL_free(buf);
OPENSSL_free(children);
return ret;
}