From de40153fa4deeec7df404b53795196d3b7f60653 Mon Sep 17 00:00:00 2001
From: PabloMK7 <hackyglitch2@gmail.com>
Date: Wed, 15 Nov 2023 01:15:50 +0100
Subject: [PATCH] Implement PS:GetRandomBytes and use openssl for random bytes
 (#7164)

---
 src/core/hle/service/ps/ps_ps.cpp  | 17 ++++++++++++-
 src/core/hle/service/ssl/ssl_c.cpp | 38 ++++++++----------------------
 src/core/hle/service/ssl/ssl_c.h   |  5 ++--
 3 files changed, 28 insertions(+), 32 deletions(-)

diff --git a/src/core/hle/service/ps/ps_ps.cpp b/src/core/hle/service/ps/ps_ps.cpp
index 32026fa0cfd..64f0a4355a9 100644
--- a/src/core/hle/service/ps/ps_ps.cpp
+++ b/src/core/hle/service/ps/ps_ps.cpp
@@ -9,6 +9,7 @@
 #include "core/core.h"
 #include "core/hle/ipc_helpers.h"
 #include "core/hle/service/ps/ps_ps.h"
+#include "core/hle/service/ssl/ssl_c.h"
 #include "core/hw/aes/arithmetic128.h"
 #include "core/hw/aes/key.h"
 
@@ -146,6 +147,20 @@ void PS_PS::EncryptDecryptAes(Kernel::HLERequestContext& ctx) {
     rb.PushMappedBuffer(destination);
 }
 
+void PS_PS::GenerateRandomBytes(Kernel::HLERequestContext& ctx) {
+    IPC::RequestParser rp(ctx);
+    const u32 size = rp.Pop<u32>();
+    auto buffer = rp.PopMappedBuffer();
+
+    std::vector<u8> out_data(size);
+    SSL::GenerateRandomData(out_data);
+    buffer.Write(out_data.data(), 0, size);
+
+    IPC::RequestBuilder rb = rp.MakeBuilder(1, 2);
+    rb.Push(RESULT_SUCCESS);
+    rb.PushMappedBuffer(buffer);
+}
+
 PS_PS::PS_PS() : ServiceFramework("ps:ps", DefaultMaxSessions) {
     static const FunctionInfo functions[] = {
         // clang-format off
@@ -160,7 +175,7 @@ PS_PS::PS_PS() : ServiceFramework("ps:ps", DefaultMaxSessions) {
         {0x000A, nullptr, "GetLocalFriendCodeSeed"},
         {0x000B, nullptr, "GetDeviceId"},
         {0x000C, nullptr, "SeedRNG"},
-        {0x000D, nullptr, "GenerateRandomBytes"},
+        {0x000D, &PS_PS::GenerateRandomBytes, "GenerateRandomBytes"},
         {0x000E, nullptr, "InterfaceForPXI_0x04010084"},
         {0x000F, nullptr, "InterfaceForPXI_0x04020082"},
         {0x0010, nullptr, "InterfaceForPXI_0x04030044"},
diff --git a/src/core/hle/service/ssl/ssl_c.cpp b/src/core/hle/service/ssl/ssl_c.cpp
index df95a72aae9..43c2b6e3005 100644
--- a/src/core/hle/service/ssl/ssl_c.cpp
+++ b/src/core/hle/service/ssl/ssl_c.cpp
@@ -2,6 +2,7 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <openssl/rand.h>
 #include "common/archives.h"
 #include "common/common_types.h"
 #include "core/core.h"
@@ -16,10 +17,6 @@ void SSL_C::Initialize(Kernel::HLERequestContext& ctx) {
     IPC::RequestParser rp(ctx);
     rp.PopPID();
 
-    // Seed random number generator when the SSL service is initialized
-    std::random_device rand_device;
-    rand_gen.seed(rand_device());
-
     // Stub, return success
     IPC::RequestBuilder rb = rp.MakeBuilder(1, 0);
     rb.Push(RESULT_SUCCESS);
@@ -27,33 +24,13 @@ void SSL_C::Initialize(Kernel::HLERequestContext& ctx) {
 
 void SSL_C::GenerateRandomData(Kernel::HLERequestContext& ctx) {
     IPC::RequestParser rp(ctx);
-    u32 size = rp.Pop<u32>();
+    const u32 size = rp.Pop<u32>();
     auto buffer = rp.PopMappedBuffer();
 
-    // Fill the output buffer with random data.
-    u32 data = 0;
-    u32 i = 0;
-    while (i < size) {
-        if ((i % 4) == 0) {
-            // The random number generator returns 4 bytes worth of data, so generate new random
-            // data when i == 0 and when i is divisible by 4
-            data = rand_gen();
-        }
-
-        if (size > 4) {
-            // Use up the entire 4 bytes of the random data for as long as possible
-            buffer.Write(&data, i, 4);
-            i += 4;
-        } else if (size == 2) {
-            buffer.Write(&data, i, 2);
-            i += 2;
-        } else {
-            buffer.Write(&data, i, 1);
-            i++;
-        }
-    }
+    std::vector<u8> out_data(size);
+    SSL::GenerateRandomData(out_data);
+    buffer.Write(out_data.data(), 0, size);
 
-    // Stub, return success
     IPC::RequestBuilder rb = rp.MakeBuilder(1, 2);
     rb.Push(RESULT_SUCCESS);
     rb.PushMappedBuffer(buffer);
@@ -96,4 +73,9 @@ void InstallInterfaces(Core::System& system) {
     std::make_shared<SSL_C>()->InstallAsService(service_manager);
 }
 
+void GenerateRandomData(std::vector<u8>& out) {
+    // Fill the output buffer with random data.
+    RAND_bytes(out.data(), static_cast<int>(out.size()));
+}
+
 } // namespace Service::SSL
diff --git a/src/core/hle/service/ssl/ssl_c.h b/src/core/hle/service/ssl/ssl_c.h
index 30b87378a08..d4bcd144913 100644
--- a/src/core/hle/service/ssl/ssl_c.h
+++ b/src/core/hle/service/ssl/ssl_c.h
@@ -21,14 +21,13 @@ class SSL_C final : public ServiceFramework<SSL_C> {
     void Initialize(Kernel::HLERequestContext& ctx);
     void GenerateRandomData(Kernel::HLERequestContext& ctx);
 
-    // TODO: Implement a proper CSPRNG in the future when actual security is needed
-    std::mt19937 rand_gen;
-
     SERVICE_SERIALIZATION_SIMPLE
 };
 
 void InstallInterfaces(Core::System& system);
 
+void GenerateRandomData(std::vector<u8>& out);
+
 } // namespace Service::SSL
 
 BOOST_CLASS_EXPORT_KEY(Service::SSL::SSL_C)