unix: use fchmodat2 in Fchmodat

The fchmodat2 syscall was added in Linux kernel 6.6. Use it in Fchmodat
if flags are given. It will return ENOSYS on older kernels (or EINVAL or
any other bogus error in some container implementations).

Fixes golang/go#61636

Change-Id: Ibbc9a08733b7186907b2fe5837cb997446c38357
Reviewed-on: https://go-review.googlesource.com/c/sys/+/539635
Reviewed-by: Heschi Kreinick <heschi@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Mauri de Souza Meneguzzo <mauri870@gmail.com>
This commit is contained in:
Tobias Klauser
2023-11-03 16:59:16 +01:00
parent ec230dae7f
commit 2d0c73638b
2 changed files with 31 additions and 8 deletions

View File

@@ -61,15 +61,23 @@ func FanotifyMark(fd int, flags uint, mask uint64, dirFd int, pathname string) (
} }
//sys fchmodat(dirfd int, path string, mode uint32) (err error) //sys fchmodat(dirfd int, path string, mode uint32) (err error)
//sys fchmodat2(dirfd int, path string, mode uint32, flags int) (err error)
func Fchmodat(dirfd int, path string, mode uint32, flags int) (err error) { func Fchmodat(dirfd int, path string, mode uint32, flags int) error {
// Linux fchmodat doesn't support the flags parameter. Mimick glibc's behavior // Linux fchmodat doesn't support the flags parameter, but fchmodat2 does.
// and check the flags. Otherwise the mode would be applied to the symlink // Try fchmodat2 if flags are specified.
// destination which is not what the user expects. if flags != 0 {
if flags&^AT_SYMLINK_NOFOLLOW != 0 { err := fchmodat2(dirfd, path, mode, flags)
return EINVAL if err == ENOSYS {
} else if flags&AT_SYMLINK_NOFOLLOW != 0 { // fchmodat2 isn't available. If the flags are known to be valid,
return EOPNOTSUPP // return EOPNOTSUPP to indicate that fchmodat doesn't support them.
if flags&^(AT_SYMLINK_NOFOLLOW|AT_EMPTY_PATH) != 0 {
return EINVAL
} else if flags&(AT_SYMLINK_NOFOLLOW|AT_EMPTY_PATH) != 0 {
return EOPNOTSUPP
}
}
return err
} }
return fchmodat(dirfd, path, mode) return fchmodat(dirfd, path, mode)
} }

View File

@@ -37,6 +37,21 @@ func fchmodat(dirfd int, path string, mode uint32) (err error) {
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
func fchmodat2(dirfd int, path string, mode uint32, flags int) (err error) {
var _p0 *byte
_p0, err = BytePtrFromString(path)
if err != nil {
return
}
_, _, e1 := Syscall6(SYS_FCHMODAT2, uintptr(dirfd), uintptr(unsafe.Pointer(_p0)), uintptr(mode), uintptr(flags), 0, 0)
if e1 != 0 {
err = errnoErr(e1)
}
return
}
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
func ioctl(fd int, req uint, arg uintptr) (err error) { func ioctl(fd int, req uint, arg uintptr) (err error) {
_, _, e1 := Syscall(SYS_IOCTL, uintptr(fd), uintptr(req), uintptr(arg)) _, _, e1 := Syscall(SYS_IOCTL, uintptr(fd), uintptr(req), uintptr(arg))
if e1 != 0 { if e1 != 0 {