Only use `clone3` when needed for pidfd

In #89522 we learned that `clone3` is interacting poorly with Gentoo's
`sandbox` tool. We only need that for the unstable pidfd extensions, so
otherwise avoid that and use a normal `fork`.
This commit is contained in:
Josh Stone 2021-10-15 12:21:45 -07:00
parent 045612b8b9
commit 85b55ce00d
1 changed files with 6 additions and 7 deletions

View File

@ -166,6 +166,10 @@ impl Command {
fn clone3(cl_args: *mut clone_args, len: libc::size_t) -> libc::c_long
}
// Bypassing libc for `clone3` can make further libc calls unsafe,
// so we use it sparingly for now. See #89522 for details.
let want_clone3_pidfd = self.get_create_pidfd();
// If we fail to create a pidfd for any reason, this will
// stay as -1, which indicates an error.
let mut pidfd: pid_t = -1;
@ -173,14 +177,9 @@ impl Command {
// Attempt to use the `clone3` syscall, which supports more arguments
// (in particular, the ability to create a pidfd). If this fails,
// we will fall through this block to a call to `fork()`
if HAS_CLONE3.load(Ordering::Relaxed) {
let mut flags = 0;
if self.get_create_pidfd() {
flags |= CLONE_PIDFD;
}
if want_clone3_pidfd && HAS_CLONE3.load(Ordering::Relaxed) {
let mut args = clone_args {
flags,
flags: CLONE_PIDFD,
pidfd: &mut pidfd as *mut pid_t as u64,
child_tid: 0,
parent_tid: 0,