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/*
* Generic ASN.1 parsing
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
*/
#include "common.h"
#if defined(MBEDTLS_ASN1_PARSE_C)
#include "mbedtls/asn1.h"
#include "mbedtls/platform_util.h"
#include "mbedtls/error.h"
#include <string.h>
#if defined(MBEDTLS_BIGNUM_C)
#include "mbedtls/bignum.h"
#endif
#include "mbedtls/platform.h"
/*
* ASN.1 DER decoding routines
*/
int mbedtls_asn1_get_len(unsigned char **p,
const unsigned char *end,
size_t *len)
{
if ((end - *p) < 1) {
return MBEDTLS_ERR_ASN1_OUT_OF_DATA;
}
if ((**p & 0x80) == 0) {
*len = *(*p)++;
} else {
switch (**p & 0x7F) {
case 1:
if ((end - *p) < 2) {
return MBEDTLS_ERR_ASN1_OUT_OF_DATA;
}
*len = (*p)[1];
(*p) += 2;
break;
case 2:
if ((end - *p) < 3) {
return MBEDTLS_ERR_ASN1_OUT_OF_DATA;
}
*len = ((size_t) (*p)[1] << 8) | (*p)[2];
(*p) += 3;
break;
case 3:
if ((end - *p) < 4) {
return MBEDTLS_ERR_ASN1_OUT_OF_DATA;
}
*len = ((size_t) (*p)[1] << 16) |
((size_t) (*p)[2] << 8) | (*p)[3];
(*p) += 4;
break;
case 4:
if ((end - *p) < 5) {
return MBEDTLS_ERR_ASN1_OUT_OF_DATA;
}
*len = ((size_t) (*p)[1] << 24) | ((size_t) (*p)[2] << 16) |
((size_t) (*p)[3] << 8) | (*p)[4];
(*p) += 5;
break;
default:
return MBEDTLS_ERR_ASN1_INVALID_LENGTH;
}
}
if (*len > (size_t) (end - *p)) {
return MBEDTLS_ERR_ASN1_OUT_OF_DATA;
}
return 0;
}
int mbedtls_asn1_get_tag(unsigned char **p,
const unsigned char *end,
size_t *len, int tag)
{
if ((end - *p) < 1) {
return MBEDTLS_ERR_ASN1_OUT_OF_DATA;
}
if (**p != tag) {
return MBEDTLS_ERR_ASN1_UNEXPECTED_TAG;
}
(*p)++;
return mbedtls_asn1_get_len(p, end, len);
}
int mbedtls_asn1_get_bool(unsigned char **p,
const unsigned char *end,
int *val)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len;
if ((ret = mbedtls_asn1_get_tag(p, end, &len, MBEDTLS_ASN1_BOOLEAN)) != 0) {
return ret;
}
if (len != 1) {
return MBEDTLS_ERR_ASN1_INVALID_LENGTH;
}
*val = (**p != 0) ? 1 : 0;
(*p)++;
return 0;
}
static int asn1_get_tagged_int(unsigned char **p,
const unsigned char *end,
int tag, int *val)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len;
if ((ret = mbedtls_asn1_get_tag(p, end, &len, tag)) != 0) {
return ret;
}
/*
* len==0 is malformed (0 must be represented as 020100 for INTEGER,
* or 0A0100 for ENUMERATED tags
*/
if (len == 0) {
return MBEDTLS_ERR_ASN1_INVALID_LENGTH;
}
/* This is a cryptography library. Reject negative integers. */
if ((**p & 0x80) != 0) {
return MBEDTLS_ERR_ASN1_INVALID_LENGTH;
}
/* Skip leading zeros. */
while (len > 0 && **p == 0) {
++(*p);
--len;
}
/* Reject integers that don't fit in an int. This code assumes that
* the int type has no padding bit. */
if (len > sizeof(int)) {
return MBEDTLS_ERR_ASN1_INVALID_LENGTH;
}
if (len == sizeof(int) && (**p & 0x80) != 0) {
return MBEDTLS_ERR_ASN1_INVALID_LENGTH;
}
*val = 0;
while (len-- > 0) {
*val = (*val << 8) | **p;
(*p)++;
}
return 0;
}
int mbedtls_asn1_get_int(unsigned char **p,
const unsigned char *end,
int *val)
{
return asn1_get_tagged_int(p, end, MBEDTLS_ASN1_INTEGER, val);
}
int mbedtls_asn1_get_enum(unsigned char **p,
const unsigned char *end,
int *val)
{
return asn1_get_tagged_int(p, end, MBEDTLS_ASN1_ENUMERATED, val);
}
#if defined(MBEDTLS_BIGNUM_C)
int mbedtls_asn1_get_mpi(unsigned char **p,
const unsigned char *end,
mbedtls_mpi *X)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len;
if ((ret = mbedtls_asn1_get_tag(p, end, &len, MBEDTLS_ASN1_INTEGER)) != 0) {
return ret;
}
ret = mbedtls_mpi_read_binary(X, *p, len);
*p += len;
return ret;
}
#endif /* MBEDTLS_BIGNUM_C */
int mbedtls_asn1_get_bitstring(unsigned char **p, const unsigned char *end,
mbedtls_asn1_bitstring *bs)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
/* Certificate type is a single byte bitstring */
if ((ret = mbedtls_asn1_get_tag(p, end, &bs->len, MBEDTLS_ASN1_BIT_STRING)) != 0) {
return ret;
}
/* Check length, subtract one for actual bit string length */
if (bs->len < 1) {
return MBEDTLS_ERR_ASN1_OUT_OF_DATA;
}
bs->len -= 1;
/* Get number of unused bits, ensure unused bits <= 7 */
bs->unused_bits = **p;
if (bs->unused_bits > 7) {
return MBEDTLS_ERR_ASN1_INVALID_LENGTH;
}
(*p)++;
/* Get actual bitstring */
bs->p = *p;
*p += bs->len;
if (*p != end) {
return MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
}
return 0;
}
/*
* Traverse an ASN.1 "SEQUENCE OF <tag>"
* and call a callback for each entry found.
*/
int mbedtls_asn1_traverse_sequence_of(
unsigned char **p,
const unsigned char *end,
unsigned char tag_must_mask, unsigned char tag_must_val,
unsigned char tag_may_mask, unsigned char tag_may_val,
int (*cb)(void *ctx, int tag,
unsigned char *start, size_t len),
void *ctx)
{
int ret;
size_t len;
/* Get main sequence tag */
if ((ret = mbedtls_asn1_get_tag(p, end, &len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) != 0) {
return ret;
}
if (*p + len != end) {
return MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
}
while (*p < end) {
unsigned char const tag = *(*p)++;
if ((tag & tag_must_mask) != tag_must_val) {
return MBEDTLS_ERR_ASN1_UNEXPECTED_TAG;
}
if ((ret = mbedtls_asn1_get_len(p, end, &len)) != 0) {
return ret;
}
if ((tag & tag_may_mask) == tag_may_val) {
if (cb != NULL) {
ret = cb(ctx, tag, *p, len);
if (ret != 0) {
return ret;
}
}
}
*p += len;
}
return 0;
}
/*
* Get a bit string without unused bits
*/
int mbedtls_asn1_get_bitstring_null(unsigned char **p, const unsigned char *end,
size_t *len)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
if ((ret = mbedtls_asn1_get_tag(p, end, len, MBEDTLS_ASN1_BIT_STRING)) != 0) {
return ret;
}
if (*len == 0) {
return MBEDTLS_ERR_ASN1_INVALID_DATA;
}
--(*len);
if (**p != 0) {
return MBEDTLS_ERR_ASN1_INVALID_DATA;
}
++(*p);
return 0;
}
void mbedtls_asn1_sequence_free(mbedtls_asn1_sequence *seq)
{
while (seq != NULL) {
mbedtls_asn1_sequence *next = seq->next;
mbedtls_platform_zeroize(seq, sizeof(*seq));
mbedtls_free(seq);
seq = next;
}
}
typedef struct {
int tag;
mbedtls_asn1_sequence *cur;
} asn1_get_sequence_of_cb_ctx_t;
static int asn1_get_sequence_of_cb(void *ctx,
int tag,
unsigned char *start,
size_t len)
{
asn1_get_sequence_of_cb_ctx_t *cb_ctx =
(asn1_get_sequence_of_cb_ctx_t *) ctx;
mbedtls_asn1_sequence *cur =
cb_ctx->cur;
if (cur->buf.p != NULL) {
cur->next =
mbedtls_calloc(1, sizeof(mbedtls_asn1_sequence));
if (cur->next == NULL) {
return MBEDTLS_ERR_ASN1_ALLOC_FAILED;
}
cur = cur->next;
}
cur->buf.p = start;
cur->buf.len = len;
cur->buf.tag = tag;
cb_ctx->cur = cur;
return 0;
}
/*
* Parses and splits an ASN.1 "SEQUENCE OF <tag>"
*/
int mbedtls_asn1_get_sequence_of(unsigned char **p,
const unsigned char *end,
mbedtls_asn1_sequence *cur,
int tag)
{
asn1_get_sequence_of_cb_ctx_t cb_ctx = { tag, cur };
memset(cur, 0, sizeof(mbedtls_asn1_sequence));
return mbedtls_asn1_traverse_sequence_of(
p, end, 0xFF, tag, 0, 0,
asn1_get_sequence_of_cb, &cb_ctx);
}
int mbedtls_asn1_get_alg(unsigned char **p,
const unsigned char *end,
mbedtls_asn1_buf *alg, mbedtls_asn1_buf *params)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len;
if ((ret = mbedtls_asn1_get_tag(p, end, &len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) != 0) {
return ret;
}
if ((end - *p) < 1) {
return MBEDTLS_ERR_ASN1_OUT_OF_DATA;
}
alg->tag = **p;
end = *p + len;
if ((ret = mbedtls_asn1_get_tag(p, end, &alg->len, MBEDTLS_ASN1_OID)) != 0) {
return ret;
}
alg->p = *p;
*p += alg->len;
if (*p == end) {
mbedtls_platform_zeroize(params, sizeof(mbedtls_asn1_buf));
return 0;
}
params->tag = **p;
(*p)++;
if ((ret = mbedtls_asn1_get_len(p, end, ¶ms->len)) != 0) {
return ret;
}
params->p = *p;
*p += params->len;
if (*p != end) {
return MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
}
return 0;
}
int mbedtls_asn1_get_alg_null(unsigned char **p,
const unsigned char *end,
mbedtls_asn1_buf *alg)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_asn1_buf params;
memset(¶ms, 0, sizeof(mbedtls_asn1_buf));
if ((ret = mbedtls_asn1_get_alg(p, end, alg, ¶ms)) != 0) {
return ret;
}
if ((params.tag != MBEDTLS_ASN1_NULL && params.tag != 0) || params.len != 0) {
return MBEDTLS_ERR_ASN1_INVALID_DATA;
}
return 0;
}
void mbedtls_asn1_free_named_data(mbedtls_asn1_named_data *cur)
{
if (cur == NULL) {
return;
}
mbedtls_free(cur->oid.p);
mbedtls_free(cur->val.p);
mbedtls_platform_zeroize(cur, sizeof(mbedtls_asn1_named_data));
}
void mbedtls_asn1_free_named_data_list(mbedtls_asn1_named_data **head)
{
mbedtls_asn1_named_data *cur;
while ((cur = *head) != NULL) {
*head = cur->next;
mbedtls_asn1_free_named_data(cur);
mbedtls_free(cur);
}
}
mbedtls_asn1_named_data *mbedtls_asn1_find_named_data(mbedtls_asn1_named_data *list,
const char *oid, size_t len)
{
while (list != NULL) {
if (list->oid.len == len &&
memcmp(list->oid.p, oid, len) == 0) {
break;
}
list = list->next;
}
return list;
}
#endif /* MBEDTLS_ASN1_PARSE_C */
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