[release-branch.go1.20] crypto/rand,runtime: switch RtlGenRandom for ProcessPrng

RtlGenRandom is a semi-undocumented API, also known as
SystemFunction036, which we use to generate random data on Windows.
It's definition, in cryptbase.dll, is an opaque wrapper for the
documented API ProcessPrng. Instead of using RtlGenRandom, switch to
using ProcessPrng, since the former is simply a wrapper for the latter,
there should be no practical change on the user side, other than a minor
change in the DLLs we load.

Updates #53192
Fixes #64412

Change-Id: Ie6891bf97b1d47f5368cccbe92f374dba2c2672a
Reviewed-on: https://go-review.googlesource.com/c/go/+/536235
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Quim Muntal <quimmuntal@gmail.com>
Auto-Submit: Roland Shoemaker <roland@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
(cherry picked from commit 693def151adff1af707d82d28f55dba81ceb08e1)
Reviewed-on: https://go-review.googlesource.com/c/go/+/545356
Auto-Submit: Dmitri Shuralyov <dmitshur@google.com>

diff --git a/src/crypto/rand/rand.go b/src/crypto/rand/rand.go
index af85b966df6e43fe35964b3b79c61fb415ab4e46..0f3dca4e0ee5370a31c190a6142a8ac1f94a4a4c 100644 (file)
--- a/src/crypto/rand/rand.go
+++ b/src/crypto/rand/rand.go
@@ -15,7 +15,7 @@ import "io"
 // available, /dev/urandom otherwise.
 // On OpenBSD and macOS, Reader uses getentropy(2).
 // On other Unix-like systems, Reader reads from /dev/urandom.
-// On Windows systems, Reader uses the RtlGenRandom API.
+// On Windows systems, Reader uses the ProcessPrng API.
 // On Wasm, Reader uses the Web Crypto API.
 var Reader io.Reader
 

diff --git a/src/crypto/rand/rand_windows.go b/src/crypto/rand/rand_windows.go
index 6c0655c72b692ae444a85025ecc3d27d65107404..7380f1f0f1e6e6ee21a912318fdefdf1655e1a0c 100644 (file)
--- a/src/crypto/rand/rand_windows.go
+++ b/src/crypto/rand/rand_windows.go
@@ -15,11 +15,8 @@ func init() { Reader = &rngReader{} }
 
 type rngReader struct{}
 
-func (r *rngReader) Read(b []byte) (n int, err error) {
-       // RtlGenRandom only returns 1<<32-1 bytes at a time. We only read at
-       // most 1<<31-1 bytes at a time so that  this works the same on 32-bit
-       // and 64-bit systems.
-       if err := batched(windows.RtlGenRandom, 1<<31-1)(b); err != nil {
+func (r *rngReader) Read(b []byte) (int, error) {
+       if err := windows.ProcessPrng(b); err != nil {
                return 0, err
        }
        return len(b), nil

diff --git a/src/internal/syscall/windows/syscall_windows.go b/src/internal/syscall/windows/syscall_windows.go
index 8ace2a27e79fcb5f84fa87b959469468050de263..b7bf886f3896302c9a37540b7e7f4195a1b3e5c4 100644 (file)
--- a/src/internal/syscall/windows/syscall_windows.go
+++ b/src/internal/syscall/windows/syscall_windows.go
@@ -366,4 +366,4 @@ func LoadGetFinalPathNameByHandle() error {
 //sys  CreateEnvironmentBlock(block **uint16, token syscall.Token, inheritExisting bool) (err error) = userenv.CreateEnvironmentBlock
 //sys  DestroyEnvironmentBlock(block *uint16) (err error) = userenv.DestroyEnvironmentBlock
 
-//sys  RtlGenRandom(buf []byte) (err error) = advapi32.SystemFunction036
+//sys  ProcessPrng(buf []byte) (err error) = bcryptprimitives.ProcessPrng

diff --git a/src/internal/syscall/windows/zsyscall_windows.go b/src/internal/syscall/windows/zsyscall_windows.go
index afd64e318e516daea2e2d429bd172a934b252200..7ed6234451fa2b27b294b8a13e6dc7b441fd34e8 100644 (file)
--- a/src/internal/syscall/windows/zsyscall_windows.go
+++ b/src/internal/syscall/windows/zsyscall_windows.go
@@ -37,13 +37,14 @@ func errnoErr(e syscall.Errno) error {
 }
 
 var (
-       modadvapi32 = syscall.NewLazyDLL(sysdll.Add("advapi32.dll"))
-       modiphlpapi = syscall.NewLazyDLL(sysdll.Add("iphlpapi.dll"))
-       modkernel32 = syscall.NewLazyDLL(sysdll.Add("kernel32.dll"))
-       modnetapi32 = syscall.NewLazyDLL(sysdll.Add("netapi32.dll"))
-       modpsapi    = syscall.NewLazyDLL(sysdll.Add("psapi.dll"))
-       moduserenv  = syscall.NewLazyDLL(sysdll.Add("userenv.dll"))
-       modws2_32   = syscall.NewLazyDLL(sysdll.Add("ws2_32.dll"))
+       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"))
+       modpsapi            = syscall.NewLazyDLL(sysdll.Add("psapi.dll"))
+       moduserenv          = syscall.NewLazyDLL(sysdll.Add("userenv.dll"))
+       modws2_32           = syscall.NewLazyDLL(sysdll.Add("ws2_32.dll"))
 
        procAdjustTokenPrivileges        = modadvapi32.NewProc("AdjustTokenPrivileges")
        procDuplicateTokenEx             = modadvapi32.NewProc("DuplicateTokenEx")
@@ -52,7 +53,7 @@ var (
        procOpenThreadToken              = modadvapi32.NewProc("OpenThreadToken")
        procRevertToSelf                 = modadvapi32.NewProc("RevertToSelf")
        procSetTokenInformation          = modadvapi32.NewProc("SetTokenInformation")
-       procSystemFunction036            = modadvapi32.NewProc("SystemFunction036")
+       procProcessPrng                  = modbcryptprimitives.NewProc("ProcessPrng")
        procGetAdaptersAddresses         = modiphlpapi.NewProc("GetAdaptersAddresses")
        procGetACP                       = modkernel32.NewProc("GetACP")
        procGetComputerNameExW           = modkernel32.NewProc("GetComputerNameExW")
@@ -144,12 +145,12 @@ func SetTokenInformation(tokenHandle syscall.Token, tokenInformationClass uint32
        return
 }
 
-func RtlGenRandom(buf []byte) (err error) {
+func ProcessPrng(buf []byte) (err error) {
        var _p0 *byte
        if len(buf) > 0 {
                _p0 = &buf[0]
        }
-       r1, _, e1 := syscall.Syscall(procSystemFunction036.Addr(), 2, uintptr(unsafe.Pointer(_p0)), uintptr(len(buf)), 0)
+       r1, _, e1 := syscall.Syscall(procProcessPrng.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 44718f1d21459e164f4dcf7f3592160ef9d81059..a88d3a8ac6ed78db6813fde4537ae559f8f3c60b 100644 (file)
--- a/src/runtime/os_windows.go
+++ b/src/runtime/os_windows.go
@@ -122,15 +122,8 @@ var (
        _LoadLibraryExW,
        _ 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
+       // Use ProcessPrng to generate cryptographically random data.
+       _ProcessPrng stdFunction
 
        // Load ntdll.dll manually during startup, otherwise Mingw
        // links wrong printf function to cgo executable (see issue
@@ -256,12 +249,12 @@ func loadOptionalSyscalls() {
        _LoadLibraryExW = windowsFindfunc(k32, []byte("LoadLibraryExW\000"))
        useLoadLibraryEx = (_LoadLibraryExW != nil && _LoadLibraryExA != nil && _AddDllDirectory != nil)
 
-       var advapi32dll = []byte("advapi32.dll\000")
-       a32 := windowsLoadSystemLib(advapi32dll)
-       if a32 == 0 {
-               throw("advapi32.dll not found")
+       var bcryptprimitivesdll = []byte("bcryptprimitives.dll\000")
+       bcryptPrimitives := windowsLoadSystemLib(bcryptprimitivesdll)
+       if bcryptPrimitives == 0 {
+               throw("bcryptprimitives.dll not found")
        }
-       _RtlGenRandom = windowsFindfunc(a32, []byte("SystemFunction036\000"))
+       _ProcessPrng = windowsFindfunc(bcryptPrimitives, []byte("ProcessPrng\000"))
 
        var ntdll = []byte("ntdll.dll\000")
        n32 := windowsLoadSystemLib(ntdll)
@@ -644,7 +637,7 @@ func initWine(k32 uintptr) {
 //go:nosplit
 func getRandomData(r []byte) {
        n := 0
-       if stdcall2(_RtlGenRandom, uintptr(unsafe.Pointer(&r[0])), uintptr(len(r)))&0xff != 0 {
+       if stdcall2(_ProcessPrng, uintptr(unsafe.Pointer(&r[0])), uintptr(len(r)))&0xff != 0 {
                n = len(r)
        }
        extendRandom(r, n)