453 lines
14 KiB
C
453 lines
14 KiB
C
/*
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* QEMU Crypto ASN.1 DER decoder
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*
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* Copyright (c) 2022 Bytedance
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* Author: lei he <helei.sig11@bytedance.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include "qemu/osdep.h"
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#include "crypto/der.h"
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typedef struct QCryptoDerEncodeNode {
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uint8_t tag;
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struct QCryptoDerEncodeNode *parent;
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struct QCryptoDerEncodeNode *next;
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/* for constructed type, data is null */
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const uint8_t *data;
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size_t dlen;
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} QCryptoDerEncodeNode;
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typedef struct QCryptoEncodeContext {
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QCryptoDerEncodeNode root;
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QCryptoDerEncodeNode *current_parent;
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QCryptoDerEncodeNode *tail;
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} QCryptoEncodeContext;
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enum QCryptoDERTypeTag {
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QCRYPTO_DER_TYPE_TAG_BOOL = 0x1,
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QCRYPTO_DER_TYPE_TAG_INT = 0x2,
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QCRYPTO_DER_TYPE_TAG_BIT_STR = 0x3,
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QCRYPTO_DER_TYPE_TAG_OCT_STR = 0x4,
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QCRYPTO_DER_TYPE_TAG_NULL = 0x5,
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QCRYPTO_DER_TYPE_TAG_OID = 0x6,
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QCRYPTO_DER_TYPE_TAG_SEQ = 0x10,
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QCRYPTO_DER_TYPE_TAG_SET = 0x11,
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};
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enum QCryptoDERTagClass {
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QCRYPTO_DER_TAG_CLASS_UNIV = 0x0,
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QCRYPTO_DER_TAG_CLASS_APPL = 0x1,
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QCRYPTO_DER_TAG_CLASS_CONT = 0x2,
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QCRYPTO_DER_TAG_CLASS_PRIV = 0x3,
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};
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enum QCryptoDERTagEnc {
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QCRYPTO_DER_TAG_ENC_PRIM = 0x0,
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QCRYPTO_DER_TAG_ENC_CONS = 0x1,
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};
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#define QCRYPTO_DER_TAG_ENC_MASK 0x20
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#define QCRYPTO_DER_TAG_ENC_SHIFT 5
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#define QCRYPTO_DER_TAG_CLASS_MASK 0xc0
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#define QCRYPTO_DER_TAG_CLASS_SHIFT 6
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#define QCRYPTO_DER_TAG_VAL_MASK 0x1f
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#define QCRYPTO_DER_SHORT_LEN_MASK 0x80
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#define QCRYPTO_DER_TAG(class, enc, val) \
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(((class) << QCRYPTO_DER_TAG_CLASS_SHIFT) | \
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((enc) << QCRYPTO_DER_TAG_ENC_SHIFT) | (val))
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/**
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* qcrypto_der_encode_length:
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* @src_len: the length of source data
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* @dst: distination to save the encoded 'length', if dst is NULL, only compute
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* the expected buffer size in bytes.
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* @dst_len: output parameter, indicates how many bytes wrote.
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*
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* Encode the 'length' part of TLV tuple.
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*/
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static void qcrypto_der_encode_length(size_t src_len,
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uint8_t *dst, size_t *dst_len)
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{
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size_t max_length = 0xFF;
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uint8_t length_bytes = 0, header_byte;
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if (src_len < QCRYPTO_DER_SHORT_LEN_MASK) {
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header_byte = src_len;
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*dst_len = 1;
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} else {
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for (length_bytes = 1; max_length < src_len; length_bytes++) {
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max_length = (max_length << 8) + max_length;
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}
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header_byte = length_bytes;
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header_byte |= QCRYPTO_DER_SHORT_LEN_MASK;
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*dst_len = length_bytes + 1;
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}
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if (!dst) {
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return;
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}
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*dst++ = header_byte;
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/* Bigendian length bytes */
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for (; length_bytes > 0; length_bytes--) {
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*dst++ = ((src_len >> (length_bytes - 1) * 8) & 0xFF);
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}
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}
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static uint8_t qcrypto_der_peek_byte(const uint8_t **data, size_t *dlen)
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{
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return **data;
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}
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static void qcrypto_der_cut_nbytes(const uint8_t **data,
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size_t *dlen,
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size_t nbytes)
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{
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*data += nbytes;
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*dlen -= nbytes;
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}
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static uint8_t qcrypto_der_cut_byte(const uint8_t **data, size_t *dlen)
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{
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uint8_t val = qcrypto_der_peek_byte(data, dlen);
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qcrypto_der_cut_nbytes(data, dlen, 1);
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return val;
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}
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static int qcrypto_der_invoke_callback(QCryptoDERDecodeCb cb, void *ctx,
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const uint8_t *value, size_t vlen,
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Error **errp)
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{
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if (!cb) {
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return 0;
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}
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return cb(ctx, value, vlen, errp);
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}
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static int qcrypto_der_extract_definite_data(const uint8_t **data, size_t *dlen,
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QCryptoDERDecodeCb cb, void *ctx,
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Error **errp)
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{
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const uint8_t *value;
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size_t vlen = 0;
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uint8_t byte_count = qcrypto_der_cut_byte(data, dlen);
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/* short format of definite-length */
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if (!(byte_count & QCRYPTO_DER_SHORT_LEN_MASK)) {
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if (byte_count > *dlen) {
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error_setg(errp, "Invalid content length: %u", byte_count);
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return -1;
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}
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value = *data;
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vlen = byte_count;
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qcrypto_der_cut_nbytes(data, dlen, vlen);
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if (qcrypto_der_invoke_callback(cb, ctx, value, vlen, errp) != 0) {
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return -1;
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}
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return vlen;
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}
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/* Ignore highest bit */
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byte_count &= ~QCRYPTO_DER_SHORT_LEN_MASK;
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/*
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* size_t is enough to store the value of length, although the DER
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* encoding standard supports larger length.
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*/
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if (byte_count > sizeof(size_t)) {
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error_setg(errp, "Invalid byte count of content length: %u",
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byte_count);
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return -1;
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}
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if (byte_count > *dlen) {
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error_setg(errp, "Invalid content length: %u", byte_count);
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return -1;
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}
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while (byte_count--) {
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vlen <<= 8;
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vlen += qcrypto_der_cut_byte(data, dlen);
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}
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if (vlen > *dlen) {
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error_setg(errp, "Invalid content length: %zu", vlen);
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return -1;
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}
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value = *data;
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qcrypto_der_cut_nbytes(data, dlen, vlen);
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if (qcrypto_der_invoke_callback(cb, ctx, value, vlen, errp) != 0) {
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return -1;
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}
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return vlen;
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}
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static int qcrypto_der_extract_data(const uint8_t **data, size_t *dlen,
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QCryptoDERDecodeCb cb, void *ctx,
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Error **errp)
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{
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uint8_t val;
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if (*dlen < 1) {
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error_setg(errp, "Need more data");
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return -1;
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}
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val = qcrypto_der_peek_byte(data, dlen);
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/* must use definite length format */
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if (val == QCRYPTO_DER_SHORT_LEN_MASK) {
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error_setg(errp, "Only definite length format is allowed");
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return -1;
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}
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return qcrypto_der_extract_definite_data(data, dlen, cb, ctx, errp);
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}
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static int qcrypto_der_decode_tlv(const uint8_t expected_tag,
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const uint8_t **data, size_t *dlen,
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QCryptoDERDecodeCb cb,
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void *ctx, Error **errp)
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{
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const uint8_t *saved_data = *data;
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size_t saved_dlen = *dlen;
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uint8_t tag;
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int data_length;
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if (*dlen < 1) {
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error_setg(errp, "Need more data");
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return -1;
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}
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tag = qcrypto_der_cut_byte(data, dlen);
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if (tag != expected_tag) {
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error_setg(errp, "Unexpected tag: expected: %u, actual: %u",
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expected_tag, tag);
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goto error;
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}
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data_length = qcrypto_der_extract_data(data, dlen, cb, ctx, errp);
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if (data_length < 0) {
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goto error;
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}
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return data_length;
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error:
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*data = saved_data;
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*dlen = saved_dlen;
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return -1;
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}
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int qcrypto_der_decode_int(const uint8_t **data, size_t *dlen,
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QCryptoDERDecodeCb cb, void *ctx, Error **errp)
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{
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const uint8_t tag = QCRYPTO_DER_TAG(QCRYPTO_DER_TAG_CLASS_UNIV,
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QCRYPTO_DER_TAG_ENC_PRIM,
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QCRYPTO_DER_TYPE_TAG_INT);
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return qcrypto_der_decode_tlv(tag, data, dlen, cb, ctx, errp);
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}
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int qcrypto_der_decode_seq(const uint8_t **data, size_t *dlen,
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QCryptoDERDecodeCb cb, void *ctx, Error **errp)
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{
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uint8_t tag = QCRYPTO_DER_TAG(QCRYPTO_DER_TAG_CLASS_UNIV,
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QCRYPTO_DER_TAG_ENC_CONS,
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QCRYPTO_DER_TYPE_TAG_SEQ);
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return qcrypto_der_decode_tlv(tag, data, dlen, cb, ctx, errp);
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}
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int qcrypto_der_decode_octet_str(const uint8_t **data, size_t *dlen,
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QCryptoDERDecodeCb cb, void *ctx, Error **errp)
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{
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uint8_t tag = QCRYPTO_DER_TAG(QCRYPTO_DER_TAG_CLASS_UNIV,
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QCRYPTO_DER_TAG_ENC_PRIM,
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QCRYPTO_DER_TYPE_TAG_OCT_STR);
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return qcrypto_der_decode_tlv(tag, data, dlen, cb, ctx, errp);
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}
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int qcrypto_der_decode_bit_str(const uint8_t **data, size_t *dlen,
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QCryptoDERDecodeCb cb, void *ctx, Error **errp)
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{
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uint8_t tag = QCRYPTO_DER_TAG(QCRYPTO_DER_TAG_CLASS_UNIV,
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QCRYPTO_DER_TAG_ENC_PRIM,
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QCRYPTO_DER_TYPE_TAG_BIT_STR);
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return qcrypto_der_decode_tlv(tag, data, dlen, cb, ctx, errp);
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}
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int qcrypto_der_decode_oid(const uint8_t **data, size_t *dlen,
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QCryptoDERDecodeCb cb, void *ctx, Error **errp)
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{
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uint8_t tag = QCRYPTO_DER_TAG(QCRYPTO_DER_TAG_CLASS_UNIV,
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QCRYPTO_DER_TAG_ENC_PRIM,
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QCRYPTO_DER_TYPE_TAG_OID);
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return qcrypto_der_decode_tlv(tag, data, dlen, cb, ctx, errp);
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}
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int qcrypto_der_decode_ctx_tag(const uint8_t **data, size_t *dlen, int tag_id,
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QCryptoDERDecodeCb cb, void *ctx, Error **errp)
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{
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uint8_t tag = QCRYPTO_DER_TAG(QCRYPTO_DER_TAG_CLASS_CONT,
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QCRYPTO_DER_TAG_ENC_CONS,
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tag_id);
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return qcrypto_der_decode_tlv(tag, data, dlen, cb, ctx, errp);
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}
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static void qcrypto_der_encode_prim(QCryptoEncodeContext *ctx, uint8_t tag,
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const uint8_t *data, size_t dlen)
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{
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QCryptoDerEncodeNode *node = g_new0(QCryptoDerEncodeNode, 1);
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size_t nbytes_len;
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node->tag = tag;
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node->data = data;
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node->dlen = dlen;
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node->parent = ctx->current_parent;
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qcrypto_der_encode_length(dlen, NULL, &nbytes_len);
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/* 1 byte for Tag, nbyte_len for Length, and dlen for Value */
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node->parent->dlen += 1 + nbytes_len + dlen;
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ctx->tail->next = node;
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ctx->tail = node;
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}
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QCryptoEncodeContext *qcrypto_der_encode_ctx_new(void)
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{
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QCryptoEncodeContext *ctx = g_new0(QCryptoEncodeContext, 1);
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ctx->current_parent = &ctx->root;
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ctx->tail = &ctx->root;
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return ctx;
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}
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static void qcrypto_der_encode_cons_begin(QCryptoEncodeContext *ctx,
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uint8_t tag)
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{
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QCryptoDerEncodeNode *node = g_new0(QCryptoDerEncodeNode, 1);
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node->tag = tag;
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node->parent = ctx->current_parent;
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ctx->current_parent = node;
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ctx->tail->next = node;
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ctx->tail = node;
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}
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static void qcrypto_der_encode_cons_end(QCryptoEncodeContext *ctx)
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{
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QCryptoDerEncodeNode *cons_node = ctx->current_parent;
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size_t nbytes_len;
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qcrypto_der_encode_length(cons_node->dlen, NULL, &nbytes_len);
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/* 1 byte for Tag, nbyte_len for Length, and dlen for Value */
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cons_node->parent->dlen += 1 + nbytes_len + cons_node->dlen;
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ctx->current_parent = cons_node->parent;
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}
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void qcrypto_der_encode_seq_begin(QCryptoEncodeContext *ctx)
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{
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uint8_t tag = QCRYPTO_DER_TAG(QCRYPTO_DER_TAG_CLASS_UNIV,
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QCRYPTO_DER_TAG_ENC_CONS,
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QCRYPTO_DER_TYPE_TAG_SEQ);
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qcrypto_der_encode_cons_begin(ctx, tag);
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}
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void qcrypto_der_encode_seq_end(QCryptoEncodeContext *ctx)
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{
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qcrypto_der_encode_cons_end(ctx);
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}
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void qcrypto_der_encode_oid(QCryptoEncodeContext *ctx,
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const uint8_t *src, size_t src_len)
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{
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uint8_t tag = QCRYPTO_DER_TAG(QCRYPTO_DER_TAG_CLASS_UNIV,
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QCRYPTO_DER_TAG_ENC_PRIM,
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QCRYPTO_DER_TYPE_TAG_OID);
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qcrypto_der_encode_prim(ctx, tag, src, src_len);
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}
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void qcrypto_der_encode_int(QCryptoEncodeContext *ctx,
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const uint8_t *src, size_t src_len)
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{
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uint8_t tag = QCRYPTO_DER_TAG(QCRYPTO_DER_TAG_CLASS_UNIV,
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QCRYPTO_DER_TAG_ENC_PRIM,
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QCRYPTO_DER_TYPE_TAG_INT);
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qcrypto_der_encode_prim(ctx, tag, src, src_len);
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}
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void qcrypto_der_encode_null(QCryptoEncodeContext *ctx)
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{
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uint8_t tag = QCRYPTO_DER_TAG(QCRYPTO_DER_TAG_CLASS_UNIV,
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QCRYPTO_DER_TAG_ENC_PRIM,
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QCRYPTO_DER_TYPE_TAG_NULL);
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qcrypto_der_encode_prim(ctx, tag, NULL, 0);
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}
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void qcrypto_der_encode_octet_str(QCryptoEncodeContext *ctx,
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const uint8_t *src, size_t src_len)
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{
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uint8_t tag = QCRYPTO_DER_TAG(QCRYPTO_DER_TAG_CLASS_UNIV,
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QCRYPTO_DER_TAG_ENC_PRIM,
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QCRYPTO_DER_TYPE_TAG_OCT_STR);
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qcrypto_der_encode_prim(ctx, tag, src, src_len);
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}
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void qcrypto_der_encode_octet_str_begin(QCryptoEncodeContext *ctx)
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{
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uint8_t tag = QCRYPTO_DER_TAG(QCRYPTO_DER_TAG_CLASS_UNIV,
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QCRYPTO_DER_TAG_ENC_PRIM,
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QCRYPTO_DER_TYPE_TAG_OCT_STR);
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qcrypto_der_encode_cons_begin(ctx, tag);
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}
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void qcrypto_der_encode_octet_str_end(QCryptoEncodeContext *ctx)
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{
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qcrypto_der_encode_cons_end(ctx);
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}
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size_t qcrypto_der_encode_ctx_buffer_len(QCryptoEncodeContext *ctx)
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{
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return ctx->root.dlen;
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}
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void qcrypto_der_encode_ctx_flush_and_free(QCryptoEncodeContext *ctx,
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uint8_t *dst)
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{
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QCryptoDerEncodeNode *node, *prev;
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size_t len;
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for (prev = &ctx->root;
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(node = prev->next) && (prev->next = node->next, 1);) {
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/* Tag */
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*dst++ = node->tag;
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/* Length */
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qcrypto_der_encode_length(node->dlen, dst, &len);
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dst += len;
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/* Value */
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if (node->data) {
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memcpy(dst, node->data, node->dlen);
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dst += node->dlen;
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}
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g_free(node);
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}
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g_free(ctx);
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}
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