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LibTLS: Always send the signature_algorithms extension

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At some point since Sep 2018, OpenSSL added a ~~bug~~ feature that makes
the default set of signature algorithms defined in TLSv1.2 unusable
without reducing what they call the "security level", which caused
communication with servers using more recent versions of openssl to
fail with "internal error".
This commit makes LibTLS always send its supported sigalgs, making the
server not default to the insecure defaults, and thus enabling us to
talk to such servers.
This commit is contained in:
Ali Mohammad Pur 2021-05-12 05:22:18 +04:30 • committed by Linus Groh
parent 0ed46103ed
commit afa98fcb55
2 changed files with 41 additions and 0 deletions
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15
Userland/Libraries/LibTLS/Handshake.cpp
View file

@ -67,6 +67,9 @@ ByteBuffer TLSv12::build_hello()
if (!m_context.extensions.SNI.is_null() && m_context.options.use_sni)
sni_length = m_context.extensions.SNI.length();
// signature_algorithms: 2b extension ID, 2b extension length, 2b vector length, 2xN signatures and hashes
extension_length += 2 + 2 + 2 + 2 * m_context.options.supported_signature_algorithms.size();
if (sni_length)
extension_length += sni_length + 9;
@ -86,6 +89,18 @@ ByteBuffer TLSv12::build_hello()
builder.append((const u8*)m_context.extensions.SNI.characters(), sni_length);
}
// signature_algorithms extension
builder.append((u16)HandshakeExtension::SignatureAlgorithms);
// Extension length
builder.append((u16)(2 + 2 * m_context.options.supported_signature_algorithms.size()));
// Vector count
builder.append((u16)(m_context.options.supported_signature_algorithms.size() * 2));
// Entries
for (auto& entry : m_context.options.supported_signature_algorithms) {
builder.append((u8)entry.hash);
builder.append((u8)entry.signature);
}
if (alpn_length) {
// TODO
VERIFY_NOT_REACHED();

26
Userland/Libraries/LibTLS/TLSv12.h
View file

@ -179,6 +179,28 @@ enum ClientVerificationStaus {
VerificationNeeded,
};
enum class HashAlgorithm : u8 {
None = 0,
MD5 = 1,
SHA1 = 2,
SHA224 = 3,
SHA256 = 4,
SHA384 = 5,
SHA512 = 6,
};
enum class SignatureAlgorithm : u8 {
Anonymous = 0,
RSA = 1,
DSA = 2,
ECDSA = 3,
};
struct SignatureAndHashAlgorithm {
HashAlgorithm hash;
SignatureAlgorithm signature;
};
struct Options {
#define OPTION_WITH_DEFAULTS(typ, name, ...) \
static typ default_##name() { return typ { __VA_ARGS__ }; } \
@ -192,6 +214,10 @@ struct Options {
CipherSuite::RSA_WITH_AES_128_GCM_SHA256)
OPTION_WITH_DEFAULTS(Version, version, Version::V12)
OPTION_WITH_DEFAULTS(Vector<SignatureAndHashAlgorithm>, supported_signature_algorithms,
{ HashAlgorithm::SHA512, SignatureAlgorithm::RSA },
{ HashAlgorithm::SHA256, SignatureAlgorithm::RSA },
{ HashAlgorithm::SHA1, SignatureAlgorithm::RSA });
OPTION_WITH_DEFAULTS(bool, use_sni, true)
OPTION_WITH_DEFAULTS(bool, use_compression, false)