From f38b6428a2d1beae784a9402368e4d7f9c7cd8c5 Mon Sep 17 00:00:00 2001 From: Tobias Klauser Date: Wed, 17 Mar 2021 11:17:02 +0100 Subject: [PATCH] crypto/rand, internal/syscall/unix: add support for getentropy syscall on darwin The getentropy syscall is available on macOS since version 10.12, which is the minimum required version since Go 1.15. Change-Id: I294259af0b11df9669e4dc5fa891d2f2f039d91a Reviewed-on: https://go-review.googlesource.com/c/go/+/302489 Trust: Tobias Klauser Reviewed-by: Ian Lance Taylor Run-TryBot: Tobias Klauser TryBot-Result: Go Bot --- .../{rand_openbsd.go => rand_getentropy.go} | 7 ++-- src/internal/syscall/unix/asm_darwin.s | 8 +++++ .../syscall/unix/getentropy_darwin.go | 32 +++++++++++++++++++ 3 files changed, 45 insertions(+), 2 deletions(-) rename src/crypto/rand/{rand_openbsd.go => rand_getentropy.go} (79%) create mode 100644 src/internal/syscall/unix/asm_darwin.s create mode 100644 src/internal/syscall/unix/getentropy_darwin.go diff --git a/src/crypto/rand/rand_openbsd.go b/src/crypto/rand/rand_getentropy.go similarity index 79% rename from src/crypto/rand/rand_openbsd.go rename to src/crypto/rand/rand_getentropy.go index 9cc39f72d1..f82018a495 100644 --- a/src/crypto/rand/rand_openbsd.go +++ b/src/crypto/rand/rand_getentropy.go @@ -2,6 +2,9 @@ // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. +//go:build darwin || openbsd +// +build darwin openbsd + package rand import ( @@ -9,10 +12,10 @@ import ( ) func init() { - altGetRandom = getRandomOpenBSD + altGetRandom = getEntropy } -func getRandomOpenBSD(p []byte) (ok bool) { +func getEntropy(p []byte) (ok bool) { // getentropy(2) returns a maximum of 256 bytes per call for i := 0; i < len(p); i += 256 { end := i + 256 diff --git a/src/internal/syscall/unix/asm_darwin.s b/src/internal/syscall/unix/asm_darwin.s new file mode 100644 index 0000000000..8fbdc1d866 --- /dev/null +++ b/src/internal/syscall/unix/asm_darwin.s @@ -0,0 +1,8 @@ +// Copyright 2021 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +#include "textflag.h" + +TEXT ·libc_getentropy_trampoline(SB),NOSPLIT,$0-0 + JMP libc_getentropy(SB) diff --git a/src/internal/syscall/unix/getentropy_darwin.go b/src/internal/syscall/unix/getentropy_darwin.go new file mode 100644 index 0000000000..6da6f84d95 --- /dev/null +++ b/src/internal/syscall/unix/getentropy_darwin.go @@ -0,0 +1,32 @@ +// Copyright 2021 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package unix + +import ( + "syscall" + "unsafe" +) + +//go:cgo_import_dynamic libc_getentropy getentropy "/usr/lib/libSystem.B.dylib" + +func libc_getentropy_trampoline() + +// GetEntropy calls the macOS getentropy system call. +func GetEntropy(p []byte) error { + _, _, errno := syscall_syscall(funcPC(libc_getentropy_trampoline), + uintptr(unsafe.Pointer(&p[0])), + uintptr(len(p)), + 0) + if errno != 0 { + return errno + } + return nil +} + +//go:linkname syscall_syscall syscall.syscall +func syscall_syscall(fn, a1, a2, a3 uintptr) (r1, r2 uintptr, err syscall.Errno) + +//go:linkname funcPC runtime.funcPC +func funcPC(f interface{}) uintptr -- 2.50.0