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206 lines
4.0 KiB
C
206 lines
4.0 KiB
C
/*
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* ASN.1 DER parsing
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* Copyright (c) 2006, Jouni Malinen <j@w1.fi>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Alternatively, this software may be distributed under the terms of BSD
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* license.
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*
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* See README and COPYING for more details.
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*/
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#include "includes.h"
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#include "common.h"
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#ifdef CONFIG_INTERNAL_X509
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#include "asn1.h"
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int asn1_get_next(const u8 *buf, size_t len, struct asn1_hdr *hdr)
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{
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const u8 *pos, *end;
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u8 tmp;
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os_memset(hdr, 0, sizeof(*hdr));
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pos = buf;
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end = buf + len;
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hdr->identifier = *pos++;
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hdr->class = hdr->identifier >> 6;
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hdr->constructed = !!(hdr->identifier & (1 << 5));
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if ((hdr->identifier & 0x1f) == 0x1f) {
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hdr->tag = 0;
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do {
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if (pos >= end) {
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wpa_printf(MSG_DEBUG, "ASN.1: Identifier "
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"underflow");
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return -1;
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}
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tmp = *pos++;
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wpa_printf(MSG_MSGDUMP, "ASN.1: Extended tag data: "
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"0x%02x", tmp);
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hdr->tag = (hdr->tag << 7) | (tmp & 0x7f);
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} while (tmp & 0x80);
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} else
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hdr->tag = hdr->identifier & 0x1f;
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tmp = *pos++;
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if (tmp & 0x80) {
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if (tmp == 0xff) {
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wpa_printf(MSG_DEBUG, "ASN.1: Reserved length "
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"value 0xff used");
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return -1;
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}
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tmp &= 0x7f; /* number of subsequent octets */
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hdr->length = 0;
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while (tmp--) {
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if (pos >= end) {
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wpa_printf(MSG_DEBUG, "ASN.1: Length "
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"underflow");
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return -1;
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}
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hdr->length = (hdr->length << 8) | *pos++;
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}
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} else {
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/* Short form - length 0..127 in one octet */
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hdr->length = tmp;
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}
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if (pos + hdr->length > end) {
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wpa_printf(MSG_DEBUG, "ASN.1: Contents underflow");
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return -1;
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}
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hdr->payload = pos;
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return 0;
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}
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int asn1_get_oid(const u8 *buf, size_t len, struct asn1_oid *oid,
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const u8 **next)
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{
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struct asn1_hdr hdr;
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const u8 *pos, *end;
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unsigned long val;
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u8 tmp;
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os_memset(oid, 0, sizeof(*oid));
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if (asn1_get_next(buf, len, &hdr) < 0 || hdr.length == 0)
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return -1;
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if (hdr.class != ASN1_CLASS_UNIVERSAL || hdr.tag != ASN1_TAG_OID) {
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wpa_printf(MSG_DEBUG, "ASN.1: Expected OID - found class %d "
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"tag 0x%x", hdr.class, hdr.tag);
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return -1;
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}
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pos = hdr.payload;
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end = hdr.payload + hdr.length;
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*next = end;
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while (pos < end) {
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val = 0;
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do {
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if (pos >= end)
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return -1;
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tmp = *pos++;
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val = (val << 7) | (tmp & 0x7f);
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} while (tmp & 0x80);
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if (oid->len >= ASN1_MAX_OID_LEN) {
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wpa_printf(MSG_DEBUG, "ASN.1: Too long OID value");
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return -1;
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}
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if (oid->len == 0) {
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/*
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* The first octet encodes the first two object
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* identifier components in (X*40) + Y formula.
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* X = 0..2.
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*/
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oid->oid[0] = val / 40;
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if (oid->oid[0] > 2)
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oid->oid[0] = 2;
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oid->oid[1] = val - oid->oid[0] * 40;
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oid->len = 2;
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} else
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oid->oid[oid->len++] = val;
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}
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return 0;
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}
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void asn1_oid_to_str(struct asn1_oid *oid, char *buf, size_t len)
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{
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char *pos = buf;
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size_t i;
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int ret;
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if (len == 0)
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return;
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buf[0] = '\0';
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for (i = 0; i < oid->len; i++) {
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ret = os_snprintf(pos, buf + len - pos,
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"%s%lu",
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i == 0 ? "" : ".", oid->oid[i]);
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if (ret < 0 || ret >= buf + len - pos)
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break;
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pos += ret;
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}
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buf[len - 1] = '\0';
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}
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static u8 rotate_bits(u8 octet)
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{
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int i;
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u8 res;
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res = 0;
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for (i = 0; i < 8; i++) {
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res <<= 1;
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if (octet & 1)
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res |= 1;
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octet >>= 1;
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}
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return res;
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}
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unsigned long asn1_bit_string_to_long(const u8 *buf, size_t len)
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{
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unsigned long val = 0;
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const u8 *pos = buf;
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/* BER requires that unused bits are zero, so we can ignore the number
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* of unused bits */
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pos++;
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if (len >= 2)
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val |= rotate_bits(*pos++);
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if (len >= 3)
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val |= ((unsigned long) rotate_bits(*pos++)) << 8;
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if (len >= 4)
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val |= ((unsigned long) rotate_bits(*pos++)) << 16;
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if (len >= 5)
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val |= ((unsigned long) rotate_bits(*pos++)) << 24;
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if (len >= 6)
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wpa_printf(MSG_DEBUG, "X509: %s - some bits ignored "
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"(BIT STRING length %lu)",
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__func__, (unsigned long) len);
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return val;
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}
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#endif /* CONFIG_INTERNAL_X509 */
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