Expose the bwrap command line at /run/agent-sandbox inside every sandbox

src/seccomp.rs

@@ -32,7 +32,7 @@
 
 use std::collections::BTreeMap;
 use std::io::{Seek, SeekFrom, Write};
-use std::os::fd::{FromRawFd, IntoRawFd, RawFd};
+use std::os::fd::{IntoRawFd, RawFd};
 use std::str::FromStr;
 
 use seccompiler::{
@@ -42,6 +42,7 @@ use seccompiler::{
 use syscalls::Sysno;
 
 use crate::SandboxError;
+use crate::memfd;
 
 /// Syscall allowlist. Includes Podman's unconditional allow set (minus syscalls
 /// we deny on top, see module docs) plus arch-specific syscalls for the targets
@@ -55,17 +56,7 @@ const ALLOWED_SYSCALLS: &[&str] = &include!("seccomp_allowlist.in");
 pub fn write_program_to_memfd() -> Result<RawFd, SandboxError> {
     let bytes = build_program_bytes()?;
 
-    // Safety: memfd_create is a normal Linux syscall. We pass a valid C string
-    // and flags=0, so the fd is created without MFD_CLOEXEC and survives exec
-    // into bwrap. The name is only a debugging label (shows up as the symlink
-    // target in /proc/<pid>/fd/<n>).
-    let raw_fd = unsafe { libc::memfd_create(c"agent-sandbox-seccomp".as_ptr(), 0) };
-    if raw_fd < 0 {
-        return Err(SandboxError::Io(std::io::Error::last_os_error()));
-    }
-
-    // Safety: raw_fd is owned by us and currently uniquely held.
-    let mut file = unsafe { std::fs::File::from_raw_fd(raw_fd) };
+    let mut file = memfd::create_inheritable(c"agent-sandbox-seccomp")?;
     file.write_all(&bytes)?;
     file.seek(SeekFrom::Start(0))?;
     // into_raw_fd consumes the File without closing the underlying fd.