go/src/syscall/syscall_linux_arm64.go
Andrew G. Morgan d1b1145cac syscall: support POSIX semantics for Linux syscalls
This change adds two new methods for invoking system calls
under Linux: syscall.AllThreadsSyscall() and
syscall.AllThreadsSyscall6().

These system call wrappers ensure that all OSThreads mirror
a common system call. The wrappers serialize execution of the
runtime to ensure no race conditions where any Go code observes
a non-atomic OS state change. As such, the syscalls have
higher runtime overhead than regular system calls, and only
need to be used where such thread (or 'm' in the parlance
of the runtime sources) consistency is required.

The new support is used to enable these functions under Linux:

  syscall.Setegid(), syscall.Seteuid(), syscall.Setgroups(),
  syscall.Setgid(), syscall.Setregid(), syscall.Setreuid(),
  syscall.Setresgid(), syscall.Setresuid() and syscall.Setuid().

They work identically to their glibc counterparts.

Extensive discussion of the background issue addressed in this
patch can be found here:

   https://github.com/golang/go/issues/1435

In the case where cgo is used, the C runtime can launch pthreads that
are not managed by the Go runtime. As such, the added
syscall.AllThreadsSyscall*() return ENOTSUP when cgo is enabled.
However, for the 9 syscall.Set*() functions listed above, when cgo is
active, these functions redirect to invoke their C.set*() equivalents
in glibc, which wraps the raw system calls with a nptl:setxid fixup
mechanism. This achieves POSIX semantics for these functions in the
combined Go and C runtime.

As a side note, the glibc/nptl:setxid support (2019-11-30) does not
extend to all security related system calls under Linux so using
native Go (CGO_ENABLED=0) and these AllThreadsSyscall*()s, where
needed, will yield more well defined/consistent behavior over all
threads of a Go program. That is, using the
syscall.AllThreadsSyscall*() wrappers for things like setting state
through SYS_PRCTL and SYS_CAPSET etc.

Fixes #1435

Change-Id: Ib1a3e16b9180f64223196a32fc0f9dce14d9105c
Reviewed-on: https://go-review.googlesource.com/c/go/+/210639
Trust: Emmanuel Odeke <emm.odeke@gmail.com>
Trust: Ian Lance Taylor <iant@golang.org>
Trust: Michael Pratt <mpratt@google.com>
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Austin Clements <austin@google.com>
2020-10-23 20:53:14 +00:00

212 lines
6.4 KiB
Go

// Copyright 2015 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 syscall
import "unsafe"
const _SYS_setgroups = SYS_SETGROUPS
func EpollCreate(size int) (fd int, err error) {
if size <= 0 {
return -1, EINVAL
}
return EpollCreate1(0)
}
//sys EpollWait(epfd int, events []EpollEvent, msec int) (n int, err error) = SYS_EPOLL_PWAIT
//sys Fchown(fd int, uid int, gid int) (err error)
//sys Fstat(fd int, stat *Stat_t) (err error)
//sys Fstatat(fd int, path string, stat *Stat_t, flags int) (err error)
//sys fstatat(dirfd int, path string, stat *Stat_t, flags int) (err error)
//sys Fstatfs(fd int, buf *Statfs_t) (err error)
//sys Ftruncate(fd int, length int64) (err error)
//sysnb Getegid() (egid int)
//sysnb Geteuid() (euid int)
//sysnb Getgid() (gid int)
//sysnb getrlimit(resource int, rlim *Rlimit) (err error)
//sysnb Getuid() (uid int)
//sys Listen(s int, n int) (err error)
//sys Pread(fd int, p []byte, offset int64) (n int, err error) = SYS_PREAD64
//sys Pwrite(fd int, p []byte, offset int64) (n int, err error) = SYS_PWRITE64
//sys Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) (err error)
//sys Seek(fd int, offset int64, whence int) (off int64, err error) = SYS_LSEEK
//sys sendfile(outfd int, infd int, offset *int64, count int) (written int, err error)
//sys Setfsgid(gid int) (err error)
//sys Setfsuid(uid int) (err error)
//sysnb setrlimit(resource int, rlim *Rlimit) (err error)
//sysnb Setreuid(ruid int, euid int) (err error)
//sys Shutdown(fd int, how int) (err error)
//sys Splice(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int64, err error)
func Stat(path string, stat *Stat_t) (err error) {
return Fstatat(_AT_FDCWD, path, stat, 0)
}
func Lchown(path string, uid int, gid int) (err error) {
return Fchownat(_AT_FDCWD, path, uid, gid, _AT_SYMLINK_NOFOLLOW)
}
func Lstat(path string, stat *Stat_t) (err error) {
return Fstatat(_AT_FDCWD, path, stat, _AT_SYMLINK_NOFOLLOW)
}
//sys Statfs(path string, buf *Statfs_t) (err error)
//sys SyncFileRange(fd int, off int64, n int64, flags int) (err error) = SYS_SYNC_FILE_RANGE2
//sys Truncate(path string, length int64) (err error)
//sys accept(s int, rsa *RawSockaddrAny, addrlen *_Socklen) (fd int, err error)
//sys accept4(s int, rsa *RawSockaddrAny, addrlen *_Socklen, flags int) (fd int, err error)
//sys bind(s int, addr unsafe.Pointer, addrlen _Socklen) (err error)
//sys connect(s int, addr unsafe.Pointer, addrlen _Socklen) (err error)
//sysnb getgroups(n int, list *_Gid_t) (nn int, err error)
//sys getsockopt(s int, level int, name int, val unsafe.Pointer, vallen *_Socklen) (err error)
//sys setsockopt(s int, level int, name int, val unsafe.Pointer, vallen uintptr) (err error)
//sysnb socket(domain int, typ int, proto int) (fd int, err error)
//sysnb socketpair(domain int, typ int, proto int, fd *[2]int32) (err error)
//sysnb getpeername(fd int, rsa *RawSockaddrAny, addrlen *_Socklen) (err error)
//sysnb getsockname(fd int, rsa *RawSockaddrAny, addrlen *_Socklen) (err error)
//sys recvfrom(fd int, p []byte, flags int, from *RawSockaddrAny, fromlen *_Socklen) (n int, err error)
//sys sendto(s int, buf []byte, flags int, to unsafe.Pointer, addrlen _Socklen) (err error)
//sys recvmsg(s int, msg *Msghdr, flags int) (n int, err error)
//sys sendmsg(s int, msg *Msghdr, flags int) (n int, err error)
//sys mmap(addr uintptr, length uintptr, prot int, flags int, fd int, offset int64) (xaddr uintptr, err error)
type sigset_t struct {
X__val [16]uint64
}
//sys pselect(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timespec, sigmask *sigset_t) (n int, err error) = SYS_PSELECT6
func Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err error) {
var ts *Timespec
if timeout != nil {
ts = &Timespec{Sec: timeout.Sec, Nsec: timeout.Usec * 1000}
}
return pselect(nfd, r, w, e, ts, nil)
}
//sysnb Gettimeofday(tv *Timeval) (err error)
func setTimespec(sec, nsec int64) Timespec {
return Timespec{Sec: sec, Nsec: nsec}
}
func setTimeval(sec, usec int64) Timeval {
return Timeval{Sec: sec, Usec: usec}
}
func futimesat(dirfd int, path string, tv *[2]Timeval) (err error) {
if tv == nil {
return utimensat(dirfd, path, nil, 0)
}
ts := []Timespec{
NsecToTimespec(TimevalToNsec(tv[0])),
NsecToTimespec(TimevalToNsec(tv[1])),
}
return utimensat(dirfd, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), 0)
}
func Time(t *Time_t) (Time_t, error) {
var tv Timeval
err := Gettimeofday(&tv)
if err != nil {
return 0, err
}
if t != nil {
*t = Time_t(tv.Sec)
}
return Time_t(tv.Sec), nil
}
func Utime(path string, buf *Utimbuf) error {
tv := []Timeval{
{Sec: buf.Actime},
{Sec: buf.Modtime},
}
return Utimes(path, tv)
}
func utimes(path string, tv *[2]Timeval) (err error) {
if tv == nil {
return utimensat(_AT_FDCWD, path, nil, 0)
}
ts := []Timespec{
NsecToTimespec(TimevalToNsec(tv[0])),
NsecToTimespec(TimevalToNsec(tv[1])),
}
return utimensat(_AT_FDCWD, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), 0)
}
func Pipe(p []int) (err error) {
if len(p) != 2 {
return EINVAL
}
var pp [2]_C_int
err = pipe2(&pp, 0)
p[0] = int(pp[0])
p[1] = int(pp[1])
return
}
//sysnb pipe2(p *[2]_C_int, flags int) (err error)
func Pipe2(p []int, flags int) (err error) {
if len(p) != 2 {
return EINVAL
}
var pp [2]_C_int
err = pipe2(&pp, flags)
p[0] = int(pp[0])
p[1] = int(pp[1])
return
}
// Getrlimit prefers the prlimit64 system call. See issue 38604.
func Getrlimit(resource int, rlim *Rlimit) error {
err := prlimit(0, resource, nil, rlim)
if err != ENOSYS {
return err
}
return getrlimit(resource, rlim)
}
// Setrlimit prefers the prlimit64 system call. See issue 38604.
func Setrlimit(resource int, rlim *Rlimit) error {
err := prlimit(0, resource, rlim, nil)
if err != ENOSYS {
return err
}
return setrlimit(resource, rlim)
}
func (r *PtraceRegs) PC() uint64 { return r.Pc }
func (r *PtraceRegs) SetPC(pc uint64) { r.Pc = pc }
func (iov *Iovec) SetLen(length int) {
iov.Len = uint64(length)
}
func (msghdr *Msghdr) SetControllen(length int) {
msghdr.Controllen = uint64(length)
}
func (cmsg *Cmsghdr) SetLen(length int) {
cmsg.Len = uint64(length)
}
func InotifyInit() (fd int, err error) {
return InotifyInit1(0)
}
//sys ppoll(fds *pollFd, nfds int, timeout *Timespec, sigmask *sigset_t) (n int, err error)
func Pause() error {
_, err := ppoll(nil, 0, nil, nil)
return err
}
func rawVforkSyscall(trap, a1 uintptr) (r1 uintptr, err Errno)