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https://github.com/RGBCube/serenity
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LibCrypto: Make a better ASN.1 parser
And use it to parse RSA keys. As a bonus, this one shouldn't be reading out of bounds or messing with the stack (as much) anymore.
This commit is contained in:
AnotherTest
Andreas Kling
parent
4d40864b9d
commit
3fe7ac0924
13 changed files with 893 additions and 624 deletions
300
Userland/Libraries/LibCrypto/ASN1/DER.cpp
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300
Userland/Libraries/LibCrypto/ASN1/DER.cpp
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/*
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* Copyright (c) 2021, the SerenityOS developers.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <AK/Bitmap.h>
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#include <AK/Utf8View.h>
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#include <LibCrypto/ASN1/DER.h>
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namespace Crypto::ASN1 {
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Result<Tag, DecodeError> Decoder::read_tag()
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{
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auto byte_or_error = read_byte();
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if (byte_or_error.is_error())
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return byte_or_error.error();
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auto byte = byte_or_error.value();
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u8 class_ = byte & 0xc0;
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u8 type = byte & 0x20;
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u8 kind = byte & 0x1f;
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if (kind == 0x1f) {
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kind = 0;
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while (byte & 0x80) {
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auto byte_or_error = read_byte();
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if (byte_or_error.is_error())
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return byte_or_error.error();
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byte = byte_or_error.value();
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kind = (kind << 7) | (byte & 0x7f);
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}
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}
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return Tag { (Kind)kind, (Class)class_, (Type)type };
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}
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Result<size_t, DecodeError> Decoder::read_length()
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{
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auto byte_or_error = read_byte();
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if (byte_or_error.is_error())
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return byte_or_error.error();
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auto byte = byte_or_error.value();
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size_t length = byte;
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if (byte & 0x80) {
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auto count = byte & 0x7f;
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if (count == 0x7f)
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return DecodeError::InvalidInputFormat;
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auto data_or_error = read_bytes(count);
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if (data_or_error.is_error())
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return data_or_error.error();
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auto data = data_or_error.value();
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length = 0;
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if (data.size() > sizeof(size_t))
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return DecodeError::Overflow;
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for (auto&& byte : data)
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length = (length << 8) | (size_t)byte;
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}
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return length;
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}
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Result<u8, DecodeError> Decoder::read_byte()
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{
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if (m_stack.is_empty())
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return DecodeError::NoInput;
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auto& entry = m_stack.last();
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if (entry.is_empty())
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return DecodeError::NotEnoughData;
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auto byte = entry[0];
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entry = entry.slice(1);
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return byte;
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}
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Result<ReadonlyBytes, DecodeError> Decoder::read_bytes(size_t length)
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{
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if (m_stack.is_empty())
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return DecodeError::NoInput;
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auto& entry = m_stack.last();
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if (entry.size() < length)
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return DecodeError::NotEnoughData;
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auto bytes = entry.slice(0, length);
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entry = entry.slice(length);
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return bytes;
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}
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Result<bool, DecodeError> Decoder::decode_boolean(ReadonlyBytes data)
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{
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if (data.size() != 1)
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return DecodeError::InvalidInputFormat;
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return data[0] == 0;
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}
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Result<UnsignedBigInteger, DecodeError> Decoder::decode_arbitrary_sized_integer(ReadonlyBytes data)
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{
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if (data.size() < 1)
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return DecodeError::NotEnoughData;
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if (data.size() > 1
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&& ((data[0] == 0xff && data[1] & 0x80)
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|| (data[0] == 0x00 && !(data[1] & 0x80)))) {
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return DecodeError::InvalidInputFormat;
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}
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bool is_negative = data[0] & 0x80;
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if (is_negative)
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return DecodeError::UnsupportedFormat;
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return UnsignedBigInteger::import_data(data.data(), data.size());
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}
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Result<StringView, DecodeError> Decoder::decode_octet_string(ReadonlyBytes bytes)
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{
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return StringView { bytes.data(), bytes.size() };
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}
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Result<std::nullptr_t, DecodeError> Decoder::decode_null(ReadonlyBytes data)
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{
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if (data.size() != 0)
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return DecodeError::InvalidInputFormat;
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return nullptr;
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}
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Result<Vector<int>, DecodeError> Decoder::decode_object_identifier(ReadonlyBytes data)
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{
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Vector<int> result;
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result.append(0); // Reserved space.
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u32 value = 0;
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for (auto&& byte : data) {
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if (value == 0 && byte == 0x80)
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return DecodeError::InvalidInputFormat;
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value = (value << 7) | (byte & 0x7f);
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if (!(byte & 0x80)) {
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result.append(value);
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value = 0;
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}
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}
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if (result.size() == 1 || result[1] >= 1600)
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return DecodeError::InvalidInputFormat;
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result[0] = result[1] / 40;
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result[1] = result[1] % 40;
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return result;
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}
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Result<StringView, DecodeError> Decoder::decode_printable_string(ReadonlyBytes data)
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{
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Utf8View view { data };
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if (!view.validate())
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return DecodeError::InvalidInputFormat;
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return StringView { data };
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}
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Result<Bitmap, DecodeError> Decoder::decode_bit_string(ReadonlyBytes data)
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{
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if (data.size() < 1)
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return DecodeError::InvalidInputFormat;
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auto unused_bits = data[0];
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// FIXME: It's rather annoying that `Bitmap` is always mutable.
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return Bitmap::wrap(const_cast<u8*>(data.offset_pointer(1)), data.size() * 8 - unused_bits);
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}
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Result<Tag, DecodeError> Decoder::peek()
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{
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if (m_stack.is_empty())
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return DecodeError::NoInput;
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if (eof())
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return DecodeError::EndOfStream;
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if (m_current_tag.has_value())
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return m_current_tag.value();
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auto tag_or_error = read_tag();
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if (tag_or_error.is_error())
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return tag_or_error.error();
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m_current_tag = tag_or_error.value();
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return m_current_tag.value();
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}
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bool Decoder::eof() const
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{
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return m_stack.is_empty() || m_stack.last().is_empty();
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}
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Optional<DecodeError> Decoder::enter()
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{
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if (m_stack.is_empty())
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return DecodeError::NoInput;
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auto tag_or_error = peek();
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if (tag_or_error.is_error())
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return tag_or_error.error();
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auto tag = tag_or_error.value();
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if (tag.type != Type::Constructed)
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return DecodeError::EnteringNonConstructedTag;
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auto length_or_error = read_length();
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if (length_or_error.is_error())
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return length_or_error.error();
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auto length = length_or_error.value();
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auto data_or_error = read_bytes(length);
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if (data_or_error.is_error())
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return data_or_error.error();
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m_current_tag.clear();
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auto data = data_or_error.value();
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m_stack.append(data);
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return {};
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}
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Optional<DecodeError> Decoder::leave()
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{
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if (m_stack.is_empty())
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return DecodeError::NoInput;
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if (m_stack.size() == 1)
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return DecodeError::LeavingMainContext;
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m_stack.take_last();
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m_current_tag.clear();
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return {};
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}
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}
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void AK::Formatter<Crypto::ASN1::DecodeError>::format(FormatBuilder& fmtbuilder, Crypto::ASN1::DecodeError error)
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{
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using Crypto::ASN1::DecodeError;
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switch (error) {
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case DecodeError::NoInput:
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return Formatter<StringView>::format(fmtbuilder, "DecodeError(No input provided)");
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case DecodeError::NonConformingType:
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return Formatter<StringView>::format(fmtbuilder, "DecodeError(Tried to read with a non-conforming type)");
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case DecodeError::EndOfStream:
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return Formatter<StringView>::format(fmtbuilder, "DecodeError(End of stream)");
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case DecodeError::NotEnoughData:
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return Formatter<StringView>::format(fmtbuilder, "DecodeError(Not enough data)");
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case DecodeError::EnteringNonConstructedTag:
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return Formatter<StringView>::format(fmtbuilder, "DecodeError(Tried to enter a primitive tag)");
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case DecodeError::LeavingMainContext:
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return Formatter<StringView>::format(fmtbuilder, "DecodeError(Tried to leave the main context)");
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case DecodeError::InvalidInputFormat:
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return Formatter<StringView>::format(fmtbuilder, "DecodeError(Input data contained invalid syntax/data)");
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case DecodeError::Overflow:
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return Formatter<StringView>::format(fmtbuilder, "DecodeError(Construction would overflow)");
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case DecodeError::UnsupportedFormat:
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return Formatter<StringView>::format(fmtbuilder, "DecodeError(Input data format not supported by this parser)");
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default:
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return Formatter<StringView>::format(fmtbuilder, "DecodeError(Unknown)");
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}
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}
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