syscall: add ptracePtr that accepts pointer arg as unsafe.Pointer

The existing ptrace wrapper accepts pointer argument as an uintptr which
often points to the memory allocated in Go. This violates unsafe.Pointer safety
rules.

Fixes #58387

Change-Id: Iab12122c495953f94ea00c2a61654a818a464205
Reviewed-on: https://go-review.googlesource.com/c/go/+/470299
TryBot-Result: Gopher Robot <[email protected]>
Run-TryBot: Dmitri Goutnik <[email protected]>
Reviewed-by: Bryan Mills <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Auto-Submit: Dmitri Goutnik <[email protected]>

Author: dmgk

src/syscall/mksyscall.pl

@@ -137,7 +137,7 @@ ($)
 	# without reading the header.
 	$text .= "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n";
 
-	if (($darwin && $func eq "ptrace1") || (($openbsd && $libc) && $func eq "ptrace")) {
+	if (($darwin && $func =~ /^ptrace1(Ptr)?$/) || (($openbsd && $libc) && $func =~ /^ptrace(Ptr)?$/)) {
 		# The ptrace function is called from forkAndExecInChild where stack
 		# growth is forbidden.
 		$text .= "//go:nosplit\n"

src/syscall/mksyscall_libc.pl

@@ -145,11 +145,13 @@ ($)
 	$sysname =~ y/A-Z/a-z/; # All libc functions are lowercase.
 
 	# Runtime import of function to allow cross-platform builds.
-	$dynimports .= "//go:cgo_import_dynamic ${sysvarname} ${sysname} \"$modname\"\n";
-	# Link symbol to proc address variable.
-	$linknames .= "//go:linkname ${sysvarname} ${sysvarname}\n";
-	# Library proc address variable.
-	push @vars, $sysvarname;
+	if($dynimports !~ /\s+${sysvarname}\s+/) {
+		$dynimports .= "//go:cgo_import_dynamic ${sysvarname} ${sysname} \"$modname\"\n";
+		# Link symbol to proc address variable.
+		$linknames .= "//go:linkname ${sysvarname} ${sysvarname}\n";
+		# Library proc address variable.
+		push @vars, $sysvarname;
+	}
 
 	# Go function header.
 	$out = join(', ', @out);

src/syscall/ptrace_darwin.go

@@ -6,9 +6,16 @@
 
 package syscall
 
+import "unsafe"
+
 // Nosplit because it is called from forkAndExecInChild.
 //
 //go:nosplit
 func ptrace(request int, pid int, addr uintptr, data uintptr) error {
 	return ptrace1(request, pid, addr, data)
 }
+
+//go:nosplit
+func ptracePtr(request int, pid int, addr unsafe.Pointer, data uintptr) error {
+	return ptrace1Ptr(request, pid, addr, data)
+}

src/syscall/ptrace_ios.go

@@ -6,9 +6,16 @@
 
 package syscall
 
+import "unsafe"
+
 // Nosplit because it is called from forkAndExecInChild.
 //
 //go:nosplit
 func ptrace(request int, pid int, addr uintptr, data uintptr) (err error) {
 	panic("unimplemented")
 }
+
+//go:nosplit
+func ptracePtr(request int, pid int, addr unsafe.Pointer, data uintptr) (err error) {
+	panic("unimplemented")
+}

src/syscall/syscall_aix.go

@@ -505,6 +505,7 @@ func (w WaitStatus) TrapCause() int { return -1 }
 
 //sys	Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error)
 //sys	ptrace64(request int, id int64, addr int64, data int, buff uintptr) (err error)
+//sys	ptrace64Ptr(request int, id int64, addr int64, data int, buff unsafe.Pointer) (err error) = ptrace64
 
 func raw_ptrace(request int, pid int, addr *byte, data *byte) Errno {
 	if request == PTRACE_TRACEME {
@@ -525,7 +526,7 @@ func ptracePeek(pid int, addr uintptr, out []byte) (count int, err error) {
 		if bsize > 1024 {
 			bsize = 1024
 		}
-		err = ptrace64(PT_READ_BLOCK, int64(pid), int64(addr), bsize, uintptr(unsafe.Pointer(&out[0])))
+		err = ptrace64Ptr(PT_READ_BLOCK, int64(pid), int64(addr), bsize, unsafe.Pointer(&out[0]))
 		if err != nil {
 			return 0, err
 		}
@@ -551,7 +552,7 @@ func ptracePoke(pid int, addr uintptr, data []byte) (count int, err error) {
 		if bsize > 1024 {
 			bsize = 1024
 		}
-		err = ptrace64(PT_WRITE_BLOCK, int64(pid), int64(addr), bsize, uintptr(unsafe.Pointer(&data[0])))
+		err = ptrace64Ptr(PT_WRITE_BLOCK, int64(pid), int64(addr), bsize, unsafe.Pointer(&data[0]))
 		if err != nil {
 			return 0, err
 		}

src/syscall/syscall_darwin_amd64.go

@@ -25,6 +25,7 @@ func setTimeval(sec, usec int64) Timeval {
 //sys	Statfs(path string, stat *Statfs_t) (err error) = SYS_statfs64
 //sys   fstatat(fd int, path string, stat *Stat_t, flags int) (err error) = SYS_fstatat64
 //sys   ptrace1(request int, pid int, addr uintptr, data uintptr) (err error) = SYS_ptrace
+//sys   ptrace1Ptr(request int, pid int, addr unsafe.Pointer, data uintptr) (err error) = SYS_ptrace
 
 func SetKevent(k *Kevent_t, fd, mode, flags int) {
 	k.Ident = uint64(fd)

src/syscall/syscall_darwin_arm64.go

@@ -25,6 +25,7 @@ func setTimeval(sec, usec int64) Timeval {
 //sys	Statfs(path string, stat *Statfs_t) (err error)
 //sys	fstatat(fd int, path string, stat *Stat_t, flags int) (err error)
 //sys	ptrace1(request int, pid int, addr uintptr, data uintptr) (err error) = SYS_ptrace
+//sys	ptrace1Ptr(request int, pid int, addr unsafe.Pointer, data uintptr) (err error) = SYS_ptrace
 
 func SetKevent(k *Kevent_t, fd, mode, flags int) {
 	k.Ident = uint64(fd)

src/syscall/syscall_linux.go

@@ -828,6 +828,7 @@ func BindToDevice(fd int, device string) (err error) {
 }
 
 //sys	ptrace(request int, pid int, addr uintptr, data uintptr) (err error)
+//sys	ptracePtr(request int, pid int, addr uintptr, data unsafe.Pointer) (err error) = SYS_PTRACE
 
 func ptracePeek(req int, pid int, addr uintptr, out []byte) (count int, err error) {
 	// The peek requests are machine-size oriented, so we wrap it
@@ -845,7 +846,7 @@ func ptracePeek(req int, pid int, addr uintptr, out []byte) (count int, err erro
 	// boundary.
 	n := 0
 	if addr%sizeofPtr != 0 {
-		err = ptrace(req, pid, addr-addr%sizeofPtr, uintptr(unsafe.Pointer(&buf[0])))
+		err = ptracePtr(req, pid, addr-addr%sizeofPtr, unsafe.Pointer(&buf[0]))
 		if err != nil {
 			return 0, err
 		}
@@ -857,7 +858,7 @@ func ptracePeek(req int, pid int, addr uintptr, out []byte) (count int, err erro
 	for len(out) > 0 {
 		// We use an internal buffer to guarantee alignment.
 		// It's not documented if this is necessary, but we're paranoid.
-		err = ptrace(req, pid, addr+uintptr(n), uintptr(unsafe.Pointer(&buf[0])))
+		err = ptracePtr(req, pid, addr+uintptr(n), unsafe.Pointer(&buf[0]))
 		if err != nil {
 			return n, err
 		}
@@ -885,7 +886,7 @@ func ptracePoke(pokeReq int, peekReq int, pid int, addr uintptr, data []byte) (c
 	n := 0
 	if addr%sizeofPtr != 0 {
 		var buf [sizeofPtr]byte
-		err = ptrace(peekReq, pid, addr-addr%sizeofPtr, uintptr(unsafe.Pointer(&buf[0])))
+		err = ptracePtr(peekReq, pid, addr-addr%sizeofPtr, unsafe.Pointer(&buf[0]))
 		if err != nil {
 			return 0, err
 		}
@@ -912,7 +913,7 @@ func ptracePoke(pokeReq int, peekReq int, pid int, addr uintptr, data []byte) (c
 	// Trailing edge.
 	if len(data) > 0 {
 		var buf [sizeofPtr]byte
-		err = ptrace(peekReq, pid, addr+uintptr(n), uintptr(unsafe.Pointer(&buf[0])))
+		err = ptracePtr(peekReq, pid, addr+uintptr(n), unsafe.Pointer(&buf[0]))
 		if err != nil {
 			return n, err
 		}
@@ -937,11 +938,11 @@ func PtracePokeData(pid int, addr uintptr, data []byte) (count int, err error) {
 }
 
 func PtraceGetRegs(pid int, regsout *PtraceRegs) (err error) {
-	return ptrace(PTRACE_GETREGS, pid, 0, uintptr(unsafe.Pointer(regsout)))
+	return ptracePtr(PTRACE_GETREGS, pid, 0, unsafe.Pointer(regsout))
 }
 
 func PtraceSetRegs(pid int, regs *PtraceRegs) (err error) {
-	return ptrace(PTRACE_SETREGS, pid, 0, uintptr(unsafe.Pointer(regs)))
+	return ptracePtr(PTRACE_SETREGS, pid, 0, unsafe.Pointer(regs))
 }
 
 func PtraceSetOptions(pid int, options int) (err error) {
@@ -950,7 +951,7 @@ func PtraceSetOptions(pid int, options int) (err error) {
 
 func PtraceGetEventMsg(pid int) (msg uint, err error) {
 	var data _C_long
-	err = ptrace(PTRACE_GETEVENTMSG, pid, 0, uintptr(unsafe.Pointer(&data)))
+	err = ptracePtr(PTRACE_GETEVENTMSG, pid, 0, unsafe.Pointer(&data))
 	msg = uint(data)
 	return
 }

src/syscall/syscall_openbsd_libc.go

@@ -67,6 +67,7 @@ func syscall9X(fn, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2 uintptr,
 //sysnb execve(path *byte, argv **byte, envp **byte) (err error)
 //sysnb exit(res int) (err error)
 //sys   ptrace(request int, pid int, addr uintptr, data uintptr) (err error)
+//sys   ptracePtr(request int, pid int, addr unsafe.Pointer, data uintptr) (err error) = SYS_ptrace
 //sysnb getentropy(p []byte) (err error)
 //sys   fstatat(fd int, path string, stat *Stat_t, flags int) (err error)
 //sys	fcntlPtr(fd int, cmd int, arg unsafe.Pointer) (val int, err error) = SYS_fcntl