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openssl/crypto/asn1/a_int.c

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/*
* Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <stdio.h>
#include "internal/cryptlib.h"
#include "internal/numbers.h"
#include <limits.h>
#include <openssl/asn1.h>
#include <openssl/bn.h>
#include "asn1_local.h"
ASN1_INTEGER *ASN1_INTEGER_dup(const ASN1_INTEGER *x)
{
return ASN1_STRING_dup(x);
}
int ASN1_INTEGER_cmp(const ASN1_INTEGER *x, const ASN1_INTEGER *y)
{
int neg, ret;
/* Compare signs */
neg = x->type & V_ASN1_NEG;
if (neg != (y->type & V_ASN1_NEG)) {
if (neg)
return -1;
else
return 1;
}
ret = ASN1_STRING_cmp(x, y);
if (neg)
return -ret;
else
return ret;
}
/*-
* This converts a big endian buffer and sign into its content encoding.
* This is used for INTEGER and ENUMERATED types.
* The internal representation is an ASN1_STRING whose data is a big endian
* representation of the value, ignoring the sign. The sign is determined by
* the type: if type & V_ASN1_NEG is true it is negative, otherwise positive.
*
* Positive integers are no problem: they are almost the same as the DER
* encoding, except if the first byte is >= 0x80 we need to add a zero pad.
*
* Negative integers are a bit trickier...
* The DER representation of negative integers is in 2s complement form.
* The internal form is converted by complementing each octet and finally
* adding one to the result. This can be done less messily with a little trick.
* If the internal form has trailing zeroes then they will become FF by the
* complement and 0 by the add one (due to carry) so just copy as many trailing
* zeros to the destination as there are in the source. The carry will add one
* to the last none zero octet: so complement this octet and add one and finally
* complement any left over until you get to the start of the string.
*
* Padding is a little trickier too. If the first bytes is > 0x80 then we pad
* with 0xff. However if the first byte is 0x80 and one of the following bytes
* is non-zero we pad with 0xff. The reason for this distinction is that 0x80
* followed by optional zeros isn't padded.
*/
/*
* If |pad| is zero, the operation is effectively reduced to memcpy,
* and if |pad| is 0xff, then it performs two's complement, ~dst + 1.
* Note that in latter case sequence of zeros yields itself, and so
* does 0x80 followed by any number of zeros. These properties are
* used elsewhere below...
*/
static void twos_complement(unsigned char *dst, const unsigned char *src,
size_t len, unsigned char pad)
{
unsigned int carry = pad & 1;
/* Begin at the end of the encoding */
dst += len;
src += len;
/* two's complement value: ~value + 1 */
while (len-- != 0) {
*(--dst) = (unsigned char)(carry += *(--src) ^ pad);
carry >>= 8;
}
}
static size_t i2c_ibuf(const unsigned char *b, size_t blen, int neg,
unsigned char **pp)
{
unsigned int pad = 0;
size_t ret, i;
unsigned char *p, pb = 0;
if (b != NULL && blen) {
ret = blen;
i = b[0];
if (!neg && (i > 127)) {
pad = 1;
pb = 0;
} else if (neg) {
pb = 0xFF;
if (i > 128) {
pad = 1;
} else if (i == 128) {
/*
* Special case [of minimal negative for given length]:
* if any other bytes non zero we pad, otherwise we don't.
*/
for (pad = 0, i = 1; i < blen; i++)
pad |= b[i];
pb = pad != 0 ? 0xffU : 0;
pad = pb & 1;
}
}
ret += pad;
} else {
ret = 1;
blen = 0; /* reduce '(b == NULL || blen == 0)' to '(blen == 0)' */
}
if (pp == NULL || (p = *pp) == NULL)
return ret;
/*
* This magically handles all corner cases, such as '(b == NULL ||
* blen == 0)', non-negative value, "negative" zero, 0x80 followed
* by any number of zeros...
*/
*p = pb;
p += pad; /* yes, p[0] can be written twice, but it's little
* price to pay for eliminated branches */
twos_complement(p, b, blen, pb);
*pp += ret;
return ret;
}
/*
* convert content octets into a big endian buffer. Returns the length
* of buffer or 0 on error: for malformed INTEGER. If output buffer is
* NULL just return length.
*/
static size_t c2i_ibuf(unsigned char *b, int *pneg,
const unsigned char *p, size_t plen)
{
int neg, pad;
/* Zero content length is illegal */
if (plen == 0) {
ASN1err(ASN1_F_C2I_IBUF, ASN1_R_ILLEGAL_ZERO_CONTENT);
return 0;
}
neg = p[0] & 0x80;
if (pneg)
*pneg = neg;
/* Handle common case where length is 1 octet separately */
if (plen == 1) {
if (b != NULL) {
if (neg)
b[0] = (p[0] ^ 0xFF) + 1;
else
b[0] = p[0];
}
return 1;
}
pad = 0;
if (p[0] == 0) {
pad = 1;
} else if (p[0] == 0xFF) {
size_t i;
/*
* Special case [of "one less minimal negative" for given length]:
* if any other bytes non zero it was padded, otherwise not.
*/
for (pad = 0, i = 1; i < plen; i++)
pad |= p[i];
pad = pad != 0 ? 1 : 0;
}
/* reject illegal padding: first two octets MSB can't match */
if (pad && (neg == (p[1] & 0x80))) {
ASN1err(ASN1_F_C2I_IBUF, ASN1_R_ILLEGAL_PADDING);
return 0;
}
/* skip over pad */
p += pad;
plen -= pad;
if (b != NULL)
twos_complement(b, p, plen, neg ? 0xffU : 0);
return plen;
}
int i2c_ASN1_INTEGER(ASN1_INTEGER *a, unsigned char **pp)
{
return i2c_ibuf(a->data, a->length, a->type & V_ASN1_NEG, pp);
}
/* Convert big endian buffer into uint64_t, return 0 on error */
static int asn1_get_uint64(uint64_t *pr, const unsigned char *b, size_t blen)
{
size_t i;
uint64_t r;
if (blen > sizeof(*pr)) {
ASN1err(ASN1_F_ASN1_GET_UINT64, ASN1_R_TOO_LARGE);
return 0;
}
if (b == NULL)
return 0;
for (r = 0, i = 0; i < blen; i++) {
r <<= 8;
r |= b[i];
}
*pr = r;
return 1;
}
/*
* Write uint64_t to big endian buffer and return offset to first
* written octet. In other words it returns offset in range from 0
* to 7, with 0 denoting 8 written octets and 7 - one.
*/
static size_t asn1_put_uint64(unsigned char b[sizeof(uint64_t)], uint64_t r)
{
size_t off = sizeof(uint64_t);
do {
b[--off] = (unsigned char)r;
} while (r >>= 8);
return off;
}
/*
* Absolute value of INT64_MIN: we can't just use -INT64_MIN as gcc produces
* overflow warnings.
*/
#define ABS_INT64_MIN ((uint64_t)INT64_MAX + (-(INT64_MIN + INT64_MAX)))
/* signed version of asn1_get_uint64 */
static int asn1_get_int64(int64_t *pr, const unsigned char *b, size_t blen,
int neg)
{
uint64_t r;
if (asn1_get_uint64(&r, b, blen) == 0)
return 0;
if (neg) {
if (r <= INT64_MAX) {
/* Most significant bit is guaranteed to be clear, negation
* is guaranteed to be meaningful in platform-neutral sense. */
*pr = -(int64_t)r;
} else if (r == ABS_INT64_MIN) {
/* This never happens if INT64_MAX == ABS_INT64_MIN, e.g.
* on ones'-complement system. */
*pr = (int64_t)(0 - r);
} else {
ASN1err(ASN1_F_ASN1_GET_INT64, ASN1_R_TOO_SMALL);
return 0;
}
} else {
if (r <= INT64_MAX) {
*pr = (int64_t)r;
} else {
ASN1err(ASN1_F_ASN1_GET_INT64, ASN1_R_TOO_LARGE);
return 0;
}
}
return 1;
}
/* Convert ASN1 INTEGER content octets to ASN1_INTEGER structure */
ASN1_INTEGER *c2i_ASN1_INTEGER(ASN1_INTEGER **a, const unsigned char **pp,
long len)
{
ASN1_INTEGER *ret = NULL;
size_t r;
int neg;
r = c2i_ibuf(NULL, NULL, *pp, len);
if (r == 0)
return NULL;
if ((a == NULL) || ((*a) == NULL)) {
ret = ASN1_INTEGER_new();
if (ret == NULL)
return NULL;
ret->type = V_ASN1_INTEGER;
} else
ret = *a;
if (ASN1_STRING_set(ret, NULL, r) == 0)
goto err;
c2i_ibuf(ret->data, &neg, *pp, len);
if (neg)
ret->type |= V_ASN1_NEG;
*pp += len;
if (a != NULL)
(*a) = ret;
return ret;
err:
ASN1err(ASN1_F_C2I_ASN1_INTEGER, ERR_R_MALLOC_FAILURE);
if ((a == NULL) || (*a != ret))
ASN1_INTEGER_free(ret);
return NULL;
}
static int asn1_string_get_int64(int64_t *pr, const ASN1_STRING *a, int itype)
{
if (a == NULL) {
ASN1err(ASN1_F_ASN1_STRING_GET_INT64, ERR_R_PASSED_NULL_PARAMETER);
return 0;
}
if ((a->type & ~V_ASN1_NEG) != itype) {
ASN1err(ASN1_F_ASN1_STRING_GET_INT64, ASN1_R_WRONG_INTEGER_TYPE);
return 0;
}
return asn1_get_int64(pr, a->data, a->length, a->type & V_ASN1_NEG);
}
static int asn1_string_set_int64(ASN1_STRING *a, int64_t r, int itype)
{
unsigned char tbuf[sizeof(r)];
size_t off;
a->type = itype;
if (r < 0) {
/* Most obvious '-r' triggers undefined behaviour for most
* common INT64_MIN. Even though below '0 - (uint64_t)r' can
* appear two's-complement centric, it does produce correct/
* expected result even on one's-complement. This is because
* cast to unsigned has to change bit pattern... */
off = asn1_put_uint64(tbuf, 0 - (uint64_t)r);
a->type |= V_ASN1_NEG;
} else {
off = asn1_put_uint64(tbuf, r);
a->type &= ~V_ASN1_NEG;
}
return ASN1_STRING_set(a, tbuf + off, sizeof(tbuf) - off);
}
static int asn1_string_get_uint64(uint64_t *pr, const ASN1_STRING *a,
int itype)
{
if (a == NULL) {
ASN1err(ASN1_F_ASN1_STRING_GET_UINT64, ERR_R_PASSED_NULL_PARAMETER);
return 0;
}
if ((a->type & ~V_ASN1_NEG) != itype) {
ASN1err(ASN1_F_ASN1_STRING_GET_UINT64, ASN1_R_WRONG_INTEGER_TYPE);
return 0;
}
if (a->type & V_ASN1_NEG) {
ASN1err(ASN1_F_ASN1_STRING_GET_UINT64, ASN1_R_ILLEGAL_NEGATIVE_VALUE);
return 0;
}
return asn1_get_uint64(pr, a->data, a->length);
}
static int asn1_string_set_uint64(ASN1_STRING *a, uint64_t r, int itype)
{
unsigned char tbuf[sizeof(r)];
size_t off;
a->type = itype;
off = asn1_put_uint64(tbuf, r);
return ASN1_STRING_set(a, tbuf + off, sizeof(tbuf) - off);
}
/*
* This is a version of d2i_ASN1_INTEGER that ignores the sign bit of ASN1
* integers: some broken software can encode a positive INTEGER with its MSB
* set as negative (it doesn't add a padding zero).
*/
ASN1_INTEGER *d2i_ASN1_UINTEGER(ASN1_INTEGER **a, const unsigned char **pp,
long length)
{
ASN1_INTEGER *ret = NULL;
const unsigned char *p;
unsigned char *s;
long len;
int inf, tag, xclass;
int i;
if ((a == NULL) || ((*a) == NULL)) {
if ((ret = ASN1_INTEGER_new()) == NULL)
return NULL;
ret->type = V_ASN1_INTEGER;
} else
ret = (*a);
p = *pp;
inf = ASN1_get_object(&p, &len, &tag, &xclass, length);
if (inf & 0x80) {
i = ASN1_R_BAD_OBJECT_HEADER;
goto err;
}
if (tag != V_ASN1_INTEGER) {
i = ASN1_R_EXPECTING_AN_INTEGER;
goto err;
}
/*
* We must OPENSSL_malloc stuff, even for 0 bytes otherwise it signifies
* a missing NULL parameter.
*/
s = OPENSSL_malloc((int)len + 1);
if (s == NULL) {
i = ERR_R_MALLOC_FAILURE;
goto err;
}
ret->type = V_ASN1_INTEGER;
if (len) {
if ((*p == 0) && (len != 1)) {
p++;
len--;
}
memcpy(s, p, (int)len);
p += len;
}
OPENSSL_free(ret->data);
ret->data = s;
ret->length = (int)len;
if (a != NULL)
(*a) = ret;
*pp = p;
return ret;
err:
ASN1err(ASN1_F_D2I_ASN1_UINTEGER, i);
if ((a == NULL) || (*a != ret))
ASN1_INTEGER_free(ret);
return NULL;
}
static ASN1_STRING *bn_to_asn1_string(const BIGNUM *bn, ASN1_STRING *ai,
int atype)
{
ASN1_INTEGER *ret;
int len;
if (ai == NULL) {
ret = ASN1_STRING_type_new(atype);
} else {
ret = ai;
ret->type = atype;
}
if (ret == NULL) {
ASN1err(ASN1_F_BN_TO_ASN1_STRING, ERR_R_NESTED_ASN1_ERROR);
goto err;
}
if (BN_is_negative(bn) && !BN_is_zero(bn))
ret->type |= V_ASN1_NEG_INTEGER;
len = BN_num_bytes(bn);
if (len == 0)
len = 1;
if (ASN1_STRING_set(ret, NULL, len) == 0) {
ASN1err(ASN1_F_BN_TO_ASN1_STRING, ERR_R_MALLOC_FAILURE);
goto err;
}
/* Correct zero case */
if (BN_is_zero(bn))
ret->data[0] = 0;
else
len = BN_bn2bin(bn, ret->data);
ret->length = len;
return ret;
err:
if (ret != ai)
ASN1_INTEGER_free(ret);
return NULL;
}
static BIGNUM *asn1_string_to_bn(const ASN1_INTEGER *ai, BIGNUM *bn,
int itype)
{
BIGNUM *ret;
if ((ai->type & ~V_ASN1_NEG) != itype) {
ASN1err(ASN1_F_ASN1_STRING_TO_BN, ASN1_R_WRONG_INTEGER_TYPE);
return NULL;
}
ret = BN_bin2bn(ai->data, ai->length, bn);
if (ret == NULL) {
ASN1err(ASN1_F_ASN1_STRING_TO_BN, ASN1_R_BN_LIB);
return NULL;
}
if (ai->type & V_ASN1_NEG)
BN_set_negative(ret, 1);
return ret;
}
int ASN1_INTEGER_get_int64(int64_t *pr, const ASN1_INTEGER *a)
{
return asn1_string_get_int64(pr, a, V_ASN1_INTEGER);
}
int ASN1_INTEGER_set_int64(ASN1_INTEGER *a, int64_t r)
{
return asn1_string_set_int64(a, r, V_ASN1_INTEGER);
}
int ASN1_INTEGER_get_uint64(uint64_t *pr, const ASN1_INTEGER *a)
{
return asn1_string_get_uint64(pr, a, V_ASN1_INTEGER);
}
int ASN1_INTEGER_set_uint64(ASN1_INTEGER *a, uint64_t r)
{
return asn1_string_set_uint64(a, r, V_ASN1_INTEGER);
}
int ASN1_INTEGER_set(ASN1_INTEGER *a, long v)
{
return ASN1_INTEGER_set_int64(a, v);
}
long ASN1_INTEGER_get(const ASN1_INTEGER *a)
{
int i;
int64_t r;
if (a == NULL)
return 0;
i = ASN1_INTEGER_get_int64(&r, a);
if (i == 0)
return -1;
if (r > LONG_MAX || r < LONG_MIN)
return -1;
return (long)r;
}
ASN1_INTEGER *BN_to_ASN1_INTEGER(const BIGNUM *bn, ASN1_INTEGER *ai)
{
return bn_to_asn1_string(bn, ai, V_ASN1_INTEGER);
}
BIGNUM *ASN1_INTEGER_to_BN(const ASN1_INTEGER *ai, BIGNUM *bn)
{
return asn1_string_to_bn(ai, bn, V_ASN1_INTEGER);
}
int ASN1_ENUMERATED_get_int64(int64_t *pr, const ASN1_ENUMERATED *a)
{
return asn1_string_get_int64(pr, a, V_ASN1_ENUMERATED);
}
int ASN1_ENUMERATED_set_int64(ASN1_ENUMERATED *a, int64_t r)
{
return asn1_string_set_int64(a, r, V_ASN1_ENUMERATED);
}
int ASN1_ENUMERATED_set(ASN1_ENUMERATED *a, long v)
{
return ASN1_ENUMERATED_set_int64(a, v);
}
long ASN1_ENUMERATED_get(const ASN1_ENUMERATED *a)
{
int i;
int64_t r;
if (a == NULL)
return 0;
if ((a->type & ~V_ASN1_NEG) != V_ASN1_ENUMERATED)
return -1;
if (a->length > (int)sizeof(long))
return 0xffffffffL;
i = ASN1_ENUMERATED_get_int64(&r, a);
if (i == 0)
return -1;
if (r > LONG_MAX || r < LONG_MIN)
return -1;
return (long)r;
}
ASN1_ENUMERATED *BN_to_ASN1_ENUMERATED(const BIGNUM *bn, ASN1_ENUMERATED *ai)
{
return bn_to_asn1_string(bn, ai, V_ASN1_ENUMERATED);
}
BIGNUM *ASN1_ENUMERATED_to_BN(const ASN1_ENUMERATED *ai, BIGNUM *bn)
{
return asn1_string_to_bn(ai, bn, V_ASN1_ENUMERATED);
}
/* Internal functions used by x_int64.c */
int c2i_uint64_int(uint64_t *ret, int *neg, const unsigned char **pp, long len)
{
unsigned char buf[sizeof(uint64_t)];
size_t buflen;
buflen = c2i_ibuf(NULL, NULL, *pp, len);
if (buflen == 0)
return 0;
if (buflen > sizeof(uint64_t)) {
ASN1err(ASN1_F_C2I_UINT64_INT, ASN1_R_TOO_LARGE);
return 0;
}
(void)c2i_ibuf(buf, neg, *pp, len);
return asn1_get_uint64(ret, buf, buflen);
}
int i2c_uint64_int(unsigned char *p, uint64_t r, int neg)
{
unsigned char buf[sizeof(uint64_t)];
size_t off;
off = asn1_put_uint64(buf, r);
return i2c_ibuf(buf + off, sizeof(buf) - off, neg, &p);
}
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