go-legacy-win7/patches/0001-Switch-ProcessPrng-back-to-RtlGenRandom.patch

From f406141ab7c4861f2738d73ea5b77733ad0aab37 Mon Sep 17 00:00:00 2001
From: Vorapol Rinsatitnon <vorapol.r@pm.me>
Date: Wed, 13 Aug 2025 21:41:22 +0700
Subject: [PATCH] Switch ProcessPrng back to RtlGenRandom

---
 src/crypto/internal/sysrand/rand_windows.go   | 13 +++++++-
 src/crypto/rand/rand.go                       |  2 +-
 .../syscall/windows/syscall_windows.go        |  2 +-
 .../syscall/windows/zsyscall_windows.go       |  7 ++---
 src/runtime/os_windows.go                     | 30 ++++++++++++-------
 5 files changed, 36 insertions(+), 18 deletions(-)

diff --git a/src/crypto/internal/sysrand/rand_windows.go b/src/crypto/internal/sysrand/rand_windows.go
index 91f1490..d23f180 100644
--- a/src/crypto/internal/sysrand/rand_windows.go
+++ b/src/crypto/internal/sysrand/rand_windows.go
@@ -7,5 +7,16 @@ package sysrand
 import "internal/syscall/windows"
 
 func read(b []byte) error {
-	return windows.ProcessPrng(b)
+	const maxChunk = 1<<31 - 1
+	for len(b) > 0 {
+		chunk := b
+		if len(chunk) > maxChunk {
+			chunk = chunk[:maxChunk]
+		}
+		if err := windows.RtlGenRandom(chunk); err != nil {
+			return err
+		}
+		b = b[len(chunk):]
+	}
+	return nil
 }
diff --git a/src/crypto/rand/rand.go b/src/crypto/rand/rand.go
index 1ca16ca..7d5cea8 100644
--- a/src/crypto/rand/rand.go
+++ b/src/crypto/rand/rand.go
@@ -22,7 +22,7 @@ import (
 //   - On legacy Linux (< 3.17), Reader opens /dev/urandom on first use.
 //   - On macOS, iOS, and OpenBSD Reader, uses arc4random_buf(3).
 //   - On NetBSD, Reader uses the kern.arandom sysctl.
-//   - On Windows, Reader uses the ProcessPrng API.
+//   - On Windows, Reader uses the RtlGenRandom API.
 //   - On js/wasm, Reader uses the Web Crypto API.
 //   - On wasip1/wasm, Reader uses random_get.
 //
diff --git a/src/internal/syscall/windows/syscall_windows.go b/src/internal/syscall/windows/syscall_windows.go
index 905cabc..94d280b 100644
--- a/src/internal/syscall/windows/syscall_windows.go
+++ b/src/internal/syscall/windows/syscall_windows.go
@@ -419,7 +419,7 @@ func ErrorLoadingGetTempPath2() error {
 //sys	DestroyEnvironmentBlock(block *uint16) (err error) = userenv.DestroyEnvironmentBlock
 //sys	CreateEvent(eventAttrs *SecurityAttributes, manualReset uint32, initialState uint32, name *uint16) (handle syscall.Handle, err error) = kernel32.CreateEventW
 
-//sys	ProcessPrng(buf []byte) (err error) = bcryptprimitives.ProcessPrng
+//sys	RtlGenRandom(buf []byte) (err error) = advapi32.SystemFunction036
 
 type FILE_ID_BOTH_DIR_INFO struct {
 	NextEntryOffset uint32
diff --git a/src/internal/syscall/windows/zsyscall_windows.go b/src/internal/syscall/windows/zsyscall_windows.go
index 90cf0b9..87d0b9e 100644
--- a/src/internal/syscall/windows/zsyscall_windows.go
+++ b/src/internal/syscall/windows/zsyscall_windows.go
@@ -38,7 +38,6 @@ func errnoErr(e syscall.Errno) error {
 
 var (
 	modadvapi32         = syscall.NewLazyDLL(sysdll.Add("advapi32.dll"))
-	modbcryptprimitives = syscall.NewLazyDLL(sysdll.Add("bcryptprimitives.dll"))
 	modiphlpapi         = syscall.NewLazyDLL(sysdll.Add("iphlpapi.dll"))
 	modkernel32         = syscall.NewLazyDLL(sysdll.Add("kernel32.dll"))
 	modnetapi32         = syscall.NewLazyDLL(sysdll.Add("netapi32.dll"))
@@ -63,7 +62,7 @@ var (
 	procQueryServiceStatus                = modadvapi32.NewProc("QueryServiceStatus")
 	procRevertToSelf                      = modadvapi32.NewProc("RevertToSelf")
 	procSetTokenInformation               = modadvapi32.NewProc("SetTokenInformation")
-	procProcessPrng                       = modbcryptprimitives.NewProc("ProcessPrng")
+	procSystemFunction036                 = modadvapi32.NewProc("SystemFunction036")
 	procGetAdaptersAddresses              = modiphlpapi.NewProc("GetAdaptersAddresses")
 	procCreateEventW                      = modkernel32.NewProc("CreateEventW")
 	procCreateIoCompletionPort            = modkernel32.NewProc("CreateIoCompletionPort")
@@ -242,12 +241,12 @@ func SetTokenInformation(tokenHandle syscall.Token, tokenInformationClass uint32
 	return
 }
 
-func ProcessPrng(buf []byte) (err error) {
+func RtlGenRandom(buf []byte) (err error) {
 	var _p0 *byte
 	if len(buf) > 0 {
 		_p0 = &buf[0]
 	}
-	r1, _, e1 := syscall.Syscall(procProcessPrng.Addr(), 2, uintptr(unsafe.Pointer(_p0)), uintptr(len(buf)), 0)
+	r1, _, e1 := syscall.Syscall(procSystemFunction036.Addr(), 2, uintptr(unsafe.Pointer(_p0)), uintptr(len(buf)), 0)
 	if r1 == 0 {
 		err = errnoErr(e1)
 	}
diff --git a/src/runtime/os_windows.go b/src/runtime/os_windows.go
index 04752f2..a6d3211 100644
--- a/src/runtime/os_windows.go
+++ b/src/runtime/os_windows.go
@@ -127,8 +127,15 @@ var (
 	_WriteFile,
 	_ stdFunction
 
-	// Use ProcessPrng to generate cryptographically random data.
-	_ProcessPrng stdFunction
+	// Use RtlGenRandom to generate cryptographically random data.
+	// This approach has been recommended by Microsoft (see issue
+	// 15589 for details).
+	// The RtlGenRandom is not listed in advapi32.dll, instead
+	// RtlGenRandom function can be found by searching for SystemFunction036.
+	// Also some versions of Mingw cannot link to SystemFunction036
+	// when building executable as Cgo. So load SystemFunction036
+	// manually during runtime startup.
+	_RtlGenRandom stdFunction
 
 	// Load ntdll.dll manually during startup, otherwise Mingw
 	// links wrong printf function to cgo executable (see issue
@@ -146,10 +153,11 @@ var (
 )
 
 var (
-	bcryptprimitivesdll = [...]uint16{'b', 'c', 'r', 'y', 'p', 't', 'p', 'r', 'i', 'm', 'i', 't', 'i', 'v', 'e', 's', '.', 'd', 'l', 'l', 0}
-	ntdlldll            = [...]uint16{'n', 't', 'd', 'l', 'l', '.', 'd', 'l', 'l', 0}
-	powrprofdll         = [...]uint16{'p', 'o', 'w', 'r', 'p', 'r', 'o', 'f', '.', 'd', 'l', 'l', 0}
-	winmmdll            = [...]uint16{'w', 'i', 'n', 'm', 'm', '.', 'd', 'l', 'l', 0}
+	advapi32dll = [...]uint16{'a', 'd', 'v', 'a', 'p', 'i', '3', '2', '.', 'd', 'l', 'l', 0}
+	ntdlldll    = [...]uint16{'n', 't', 'd', 'l', 'l', '.', 'd', 'l', 'l', 0}
+	powrprofdll = [...]uint16{'p', 'o', 'w', 'r', 'p', 'r', 'o', 'f', '.', 'd', 'l', 'l', 0}
+	winmmdll    = [...]uint16{'w', 'i', 'n', 'm', 'm', '.', 'd', 'l', 'l', 0}
+	ws2_32dll   = [...]uint16{'w', 's', '2', '_', '3', '2', '.', 'd', 'l', 'l', 0}
 )
 
 // Function to be called by windows CreateThread
@@ -263,11 +271,11 @@ func windows_QueryPerformanceFrequency() int64 {
 }
 
 func loadOptionalSyscalls() {
-	bcryptPrimitives := windowsLoadSystemLib(bcryptprimitivesdll[:])
-	if bcryptPrimitives == 0 {
-		throw("bcryptprimitives.dll not found")
+	a32 := windowsLoadSystemLib(advapi32dll[:])
+	if a32 == 0 {
+		throw("advapi32.dll not found")
 	}
-	_ProcessPrng = windowsFindfunc(bcryptPrimitives, []byte("ProcessPrng\000"))
+	_RtlGenRandom = windowsFindfunc(a32, []byte("SystemFunction036\000"))
 
 	n32 := windowsLoadSystemLib(ntdlldll[:])
 	if n32 == 0 {
@@ -500,7 +508,7 @@ func osinit() {
 //go:nosplit
 func readRandom(r []byte) int {
 	n := 0
-	if stdcall2(_ProcessPrng, uintptr(unsafe.Pointer(&r[0])), uintptr(len(r)))&0xff != 0 {
+	if stdcall2(_RtlGenRandom, uintptr(unsafe.Pointer(&r[0])), uintptr(len(r)))&0xff != 0 {
 		n = len(r)
 	}
 	return n
-- 
2.39.5