Auto merge of #89924 - cuviper:beta-clone3, r=Mark-Simulacrum
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`.
r? `@Mark-Simulacrum`
diff --git a/library/std/src/sys/unix/process/process_unix.rs b/library/std/src/sys/unix/process/process_unix.rs
index 12edf04..11d23a3 100644
--- a/library/std/src/sys/unix/process/process_unix.rs
+++ b/library/std/src/sys/unix/process/process_unix.rs
@@ -166,6 +166,12 @@
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.
+ // Some tools (e.g. sandboxing tools) may also expect `fork`
+ // rather than `clone3`.
+ let want_clone3 = 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;
@@ -173,7 +179,7 @@
// 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) {
+ if want_clone3 && HAS_CLONE3.load(Ordering::Relaxed) {
let mut flags = 0;
if self.get_create_pidfd() {
flags |= CLONE_PIDFD;
@@ -212,8 +218,8 @@
}
}
- // If we get here, the 'clone3' syscall does not exist
- // or we do not have permission to call it
+ // Generally, we just call `fork`. If we get here after wanting `clone3`,
+ // then the syscall does not exist or we do not have permission to call it.
cvt(libc::fork()).map(|res| (res, pidfd))
}
