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syscallcompat: Use pthread_setugid_np() to implement *User() functions on macOS.

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Fixes -allow_other mode on macOS.
This commit is contained in:
Sebastian Lackner 2019-01-13 18:12:00 +01:00 committed by rfjakob
parent e885f08746
commit d7be766851
1 changed files with 56 additions and 15 deletions
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71
internal/syscallcompat/sys_darwin.go
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@ -2,6 +2,7 @@ package syscallcompat
import (
"log"
"runtime"
"syscall"
"golang.org/x/sys/unix"
@ -16,8 +17,22 @@ const (
// O_PATH is only defined on Linux
O_PATH = 0
// KAUTH_UID_NONE and KAUTH_GID_NONE are special values to
// revert permissions to the process credentials.
KAUTH_UID_NONE = ^uint32(0) - 100
KAUTH_GID_NONE = ^uint32(0) - 100
)
// Unfortunately pthread_setugid_np does not have a syscall wrapper yet.
func pthread_setugid_np(uid uint32, gid uint32) (err error) {
_, _, e1 := syscall.RawSyscall(syscall.SYS_SETTID, uintptr(uid), uintptr(gid), 0)
if e1 != 0 {
err = e1
}
return
}
// Sorry, fallocate is not available on OSX at all and
// fcntl F_PREALLOCATE is not accessible from Go.
// See https://github.com/rfjakob/gocryptfs/issues/18 if you want to help.
@ -47,9 +62,16 @@ func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error)
}
func OpenatUser(dirfd int, path string, flags int, mode uint32, context *fuse.Context) (fd int, err error) {
// FIXME: take into account context.Owner
// Until we have that, filter SUID and SGID bits:
mode = filterSuidSgid(mode)
if context != nil {
runtime.LockOSThread()
defer runtime.UnlockOSThread()
err = pthread_setugid_np(context.Owner.Uid, context.Owner.Gid)
if err != nil {
return -1, err
}
defer pthread_setugid_np(KAUTH_UID_NONE, KAUTH_GID_NONE)
}
return Openat(dirfd, path, flags, mode)
}
@ -67,9 +89,16 @@ func Mknodat(dirfd int, path string, mode uint32, dev int) (err error) {
}
func MknodatUser(dirfd int, path string, mode uint32, dev int, context *fuse.Context) (err error) {
// FIXME: take into account context.Owner
// Until we have that, filter SUID and SGID bits:
mode = filterSuidSgid(mode)
if context != nil {
runtime.LockOSThread()
defer runtime.UnlockOSThread()
err = pthread_setugid_np(context.Owner.Uid, context.Owner.Gid)
if err != nil {
return err
}
defer pthread_setugid_np(KAUTH_UID_NONE, KAUTH_GID_NONE)
}
return Mknodat(dirfd, path, mode, dev)
}
@ -87,7 +116,17 @@ func Symlinkat(oldpath string, newdirfd int, newpath string) (err error) {
}
func SymlinkatUser(oldpath string, newdirfd int, newpath string, context *fuse.Context) (err error) {
// FIXME: take into account context.Owner
if context != nil {
runtime.LockOSThread()
defer runtime.UnlockOSThread()
err = pthread_setugid_np(context.Owner.Uid, context.Owner.Gid)
if err != nil {
return err
}
defer pthread_setugid_np(KAUTH_UID_NONE, KAUTH_GID_NONE)
}
return Symlinkat(oldpath, newdirfd, newpath)
}
@ -96,9 +135,16 @@ func Mkdirat(dirfd int, path string, mode uint32) (err error) {
}
func MkdiratUser(dirfd int, path string, mode uint32, context *fuse.Context) (err error) {
// FIXME: take into account context.Owner
// Until we have that, filter SUID and SGID bits:
mode = filterSuidSgid(mode)
if context != nil {
runtime.LockOSThread()
defer runtime.UnlockOSThread()
err = pthread_setugid_np(context.Owner.Uid, context.Owner.Gid)
if err != nil {
return err
}
defer pthread_setugid_np(KAUTH_UID_NONE, KAUTH_GID_NONE)
}
return Mkdirat(dirfd, path, mode)
}
@ -110,8 +156,3 @@ func Fstatat(dirfd int, path string, stat *unix.Stat_t, flags int) (err error) {
func Getdents(fd int) ([]fuse.DirEntry, error) {
return emulateGetdents(fd)
}
// filterSuidSgid removes SUID and SGID bits from "mode".
func filterSuidSgid(mode uint32) uint32 {
return mode & ^uint32(syscall.S_ISGID|syscall.S_ISUID)
}