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src: refactor DH groups to delete crypto_groups.h
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Rewrite FindDiffieHellmanGroup() using OpenSSL helper functions to
obtain the required constants directly, instead of loading them from
our own crypto_groups.h and converting them to BIGNUMs.

This also removes the need for the struct modp_group, so we can delete
crypto_groups.h altogether.

PR-URL: #43896
Reviewed-By: Filip Skokan <panva.ip@gmail.com>
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tniessen authored Jul 25, 2022
1 parent 771e509 commit 3e6e908
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Showing 4 changed files with 39 additions and 432 deletions.
52 changes: 37 additions & 15 deletions src/crypto/crypto_dh.cc
Original file line number Diff line number Diff line change
@@ -1,7 +1,6 @@
#include "crypto/crypto_dh.h"
#include "async_wrap-inl.h"
#include "base_object-inl.h"
#include "crypto/crypto_groups.h"
#include "crypto/crypto_keys.h"
#include "env-inl.h"
#include "memory_tracker-inl.h"
Expand Down Expand Up @@ -138,6 +137,15 @@ void DiffieHellman::MemoryInfo(MemoryTracker* tracker) const {
tracker->TrackFieldWithSize("dh", dh_ ? kSizeOf_DH : 0);
}

bool DiffieHellman::Init(BignumPointer&& bn_p, int g) {
dh_.reset(DH_new());
CHECK_GE(g, 2);
BignumPointer bn_g(BN_new());
return bn_g && BN_set_word(bn_g.get(), g) &&
DH_set0_pqg(dh_.get(), bn_p.release(), nullptr, bn_g.release()) &&
VerifyContext();
}

bool DiffieHellman::Init(const char* p, int p_len, int g) {
dh_.reset(DH_new());
if (p_len <= 0) {
Expand Down Expand Up @@ -192,11 +200,29 @@ bool DiffieHellman::Init(const char* p, int p_len, const char* g, int g_len) {
return VerifyContext();
}

inline const modp_group* FindDiffieHellmanGroup(const char* name) {
for (const modp_group& group : modp_groups) {
if (StringEqualNoCase(name, group.name))
return &group;
}
constexpr int kStandardizedGenerator = 2;

template <BIGNUM* (*p)(BIGNUM*)>
BignumPointer InstantiateStandardizedGroup() {
return BignumPointer(p(nullptr));
}

typedef BignumPointer (*StandardizedGroupInstantiator)();

// Returns a function that can be used to create an instance of a standardized
// Diffie-Hellman group. The generator is always kStandardizedGenerator.
inline StandardizedGroupInstantiator FindDiffieHellmanGroup(const char* name) {
#define V(n, p) \
if (StringEqualNoCase(name, n)) return InstantiateStandardizedGroup<p>
V("modp1", BN_get_rfc2409_prime_768);
V("modp2", BN_get_rfc2409_prime_1024);
V("modp5", BN_get_rfc3526_prime_1536);
V("modp14", BN_get_rfc3526_prime_2048);
V("modp15", BN_get_rfc3526_prime_3072);
V("modp16", BN_get_rfc3526_prime_4096);
V("modp17", BN_get_rfc3526_prime_6144);
V("modp18", BN_get_rfc3526_prime_8192);
#undef V
return nullptr;
}

Expand All @@ -211,13 +237,11 @@ void DiffieHellman::DiffieHellmanGroup(
bool initialized = false;

const node::Utf8Value group_name(env->isolate(), args[0]);
const modp_group* group = FindDiffieHellmanGroup(*group_name);
auto group = FindDiffieHellmanGroup(*group_name);
if (group == nullptr)
return THROW_ERR_CRYPTO_UNKNOWN_DH_GROUP(env);

initialized = diffieHellman->Init(group->prime,
group->prime_size,
group->gen);
initialized = diffieHellman->Init(group(), kStandardizedGenerator);
if (!initialized)
THROW_ERR_CRYPTO_INITIALIZATION_FAILED(env);
}
Expand Down Expand Up @@ -480,16 +504,14 @@ Maybe<bool> DhKeyGenTraits::AdditionalConfig(

if (args[*offset]->IsString()) {
Utf8Value group_name(env->isolate(), args[*offset]);
const modp_group* group = FindDiffieHellmanGroup(*group_name);
auto group = FindDiffieHellmanGroup(*group_name);
if (group == nullptr) {
THROW_ERR_CRYPTO_UNKNOWN_DH_GROUP(env);
return Nothing<bool>();
}

params->params.prime = BignumPointer(
BN_bin2bn(reinterpret_cast<const unsigned char*>(group->prime),
group->prime_size, nullptr));
params->params.generator = group->gen;
params->params.prime = group();
params->params.generator = kStandardizedGenerator;
*offset += 1;
} else {
if (args[*offset]->IsInt32()) {
Expand Down
1 change: 1 addition & 0 deletions src/crypto/crypto_dh.h
Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@ class DiffieHellman : public BaseObject {
static void RegisterExternalReferences(ExternalReferenceRegistry* registry);

bool Init(int primeLength, int g);
bool Init(BignumPointer&& bn_p, int g);
bool Init(const char* p, int p_len, int g);
bool Init(const char* p, int p_len, const char* g, int g_len);

Expand Down
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