syscall: disable Setuid/Setgid on linux

Update #1435

This proposal disables Setuid and Setgid on all linux platforms.

Issue 1435 has been open for a long time, and it is unlikely to be addressed soon so an argument was made by a commenter

https://code.google.com/p/go/issues/detail?id=1435#c45

That these functions should made to fail rather than succeed in their broken state.

LGTM=ruiu, iant
R=iant, ruiu
CC=golang-codereviews
https://golang.org/cl/106170043

src/pkg/syscall/syscall_linux.go

@@ -807,7 +807,20 @@ func Mount(source string, target string, fstype string, flags uintptr, data stri
 //sysnb	Setpgid(pid int, pgid int) (err error)
 //sysnb	Setsid() (pid int, err error)
 //sysnb	Settimeofday(tv *Timeval) (err error)
-//sysnb	Setuid(uid int) (err error)
+
+// issue 1435.
+// On linux Setuid and Setgid only affects the current thread, not the process.
+// This does not match what most callers expect so we must return an error
+// here rather than letting the caller think that the call succeeded.
+
+func Setuid(uid int) (err error) {
+	return EOPNOTSUPP
+}
+
+func Setgid(uid int) (err error) {
+	return EOPNOTSUPP
+}
+
 //sys	Setpriority(which int, who int, prio int) (err error)
 //sys	Setxattr(path string, attr string, data []byte, flags int) (err error)
 //sys	Symlink(oldpath string, newpath string) (err error)

src/pkg/syscall/syscall_linux_386.go

@@ -47,7 +47,6 @@ func NsecToTimeval(nsec int64) (tv Timeval) {
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) = SYS_SENDFILE64
 //sys	Setfsgid(gid int) (err error) = SYS_SETFSGID32
 //sys	Setfsuid(uid int) (err error) = SYS_SETFSUID32
-//sysnb	Setgid(gid int) (err error) = SYS_SETGID32
 //sysnb	Setregid(rgid int, egid int) (err error) = SYS_SETREGID32
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error) = SYS_SETRESGID32
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error) = SYS_SETRESUID32

src/pkg/syscall/syscall_linux_amd64.go

@@ -26,7 +26,6 @@ package syscall
 //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	Setgid(gid int) (err error)
 //sysnb	Setregid(rgid int, egid int) (err error)
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error)

src/pkg/syscall/syscall_linux_arm.go

@@ -68,7 +68,6 @@ func Seek(fd int, offset int64, whence int) (newoffset int64, err error) {
 //sys	Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err error) = SYS__NEWSELECT
 //sys	Setfsgid(gid int) (err error) = SYS_SETFSGID32
 //sys	Setfsuid(uid int) (err error) = SYS_SETFSUID32
-//sysnb	Setgid(gid int) (err error) = SYS_SETGID32
 //sysnb	Setregid(rgid int, egid int) (err error) = SYS_SETREGID32
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error) = SYS_SETRESGID32
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error) = SYS_SETRESUID32

src/pkg/syscall/zsyscall_linux_386.go

@@ -1005,16 +1005,6 @@ func Settimeofday(tv *Timeval) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setuid(uid int) (err error) {
-	_, _, e1 := RawSyscall(SYS_SETUID, uintptr(uid), 0, 0)
-	if e1 != 0 {
-		err = e1
-	}
-	return
-}
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func Setpriority(which int, who int, prio int) (err error) {
 	_, _, e1 := Syscall(SYS_SETPRIORITY, uintptr(which), uintptr(who), uintptr(prio))
 	if e1 != 0 {
@@ -1553,16 +1543,6 @@ func Setfsuid(uid int) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setgid(gid int) (err error) {
-	_, _, e1 := RawSyscall(SYS_SETGID32, uintptr(gid), 0, 0)
-	if e1 != 0 {
-		err = e1
-	}
-	return
-}
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func Setregid(rgid int, egid int) (err error) {
 	_, _, e1 := RawSyscall(SYS_SETREGID32, uintptr(rgid), uintptr(egid), 0)
 	if e1 != 0 {

src/pkg/syscall/zsyscall_linux_amd64.go

@@ -1005,16 +1005,6 @@ func Settimeofday(tv *Timeval) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setuid(uid int) (err error) {
-	_, _, e1 := RawSyscall(SYS_SETUID, uintptr(uid), 0, 0)
-	if e1 != 0 {
-		err = e1
-	}
-	return
-}
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func Setpriority(which int, who int, prio int) (err error) {
 	_, _, e1 := Syscall(SYS_SETPRIORITY, uintptr(which), uintptr(who), uintptr(prio))
 	if e1 != 0 {
@@ -1605,16 +1595,6 @@ func Setfsuid(uid int) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setgid(gid int) (err error) {
-	_, _, e1 := RawSyscall(SYS_SETGID, uintptr(gid), 0, 0)
-	if e1 != 0 {
-		err = e1
-	}
-	return
-}
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func Setregid(rgid int, egid int) (err error) {
 	_, _, e1 := RawSyscall(SYS_SETREGID, uintptr(rgid), uintptr(egid), 0)
 	if e1 != 0 {

src/pkg/syscall/zsyscall_linux_arm.go

@@ -1005,16 +1005,6 @@ func Settimeofday(tv *Timeval) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setuid(uid int) (err error) {
-	_, _, e1 := RawSyscall(SYS_SETUID, uintptr(uid), 0, 0)
-	if e1 != 0 {
-		err = e1
-	}
-	return
-}
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func Setpriority(which int, who int, prio int) (err error) {
 	_, _, e1 := Syscall(SYS_SETPRIORITY, uintptr(which), uintptr(who), uintptr(prio))
 	if e1 != 0 {
@@ -1689,16 +1679,6 @@ func Setfsuid(uid int) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setgid(gid int) (err error) {
-	_, _, e1 := RawSyscall(SYS_SETGID32, uintptr(gid), 0, 0)
-	if e1 != 0 {
-		err = e1
-	}
-	return
-}
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func Setregid(rgid int, egid int) (err error) {
 	_, _, e1 := RawSyscall(SYS_SETREGID32, uintptr(rgid), uintptr(egid), 0)
 	if e1 != 0 {