starnix_modules_userfaultfd/
syscalls.rs

1// Copyright 2026 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5use starnix_core::security;
6use starnix_core::task::CurrentTask;
7use starnix_core::vfs::{FdFlags, FdNumber};
8use starnix_logging::track_stub;
9
10use starnix_uapi::auth::CAP_SYS_PTRACE;
11use starnix_uapi::errors::Errno;
12use starnix_uapi::open_flags::OpenFlags;
13use starnix_uapi::{O_CLOEXEC, O_NONBLOCK, UFFD_USER_MODE_ONLY, error};
14
15use crate::userfault_file::UserFaultFile;
16
17pub fn sys_userfaultfd(current_task: &CurrentTask, raw_flags: u32) -> Result<FdNumber, Errno> {
18    let unknown_flags = raw_flags & !(O_CLOEXEC | O_NONBLOCK | UFFD_USER_MODE_ONLY);
19    if unknown_flags != 0 {
20        return error!(EINVAL, format!("unknown flags provided: {unknown_flags:x?}"));
21    }
22    let mut open_flags = OpenFlags::empty();
23    if raw_flags & O_NONBLOCK != 0 {
24        open_flags |= OpenFlags::NONBLOCK;
25    }
26    if raw_flags & O_CLOEXEC != 0 {
27        open_flags |= OpenFlags::CLOEXEC;
28    }
29
30    let fd_flags = if raw_flags & O_CLOEXEC != 0 {
31        FdFlags::CLOEXEC
32    } else {
33        track_stub!(TODO("https://fxbug.dev/297375964"), "userfaultfds that survive exec()");
34        return error!(ENOSYS);
35    };
36
37    let user_mode_only = raw_flags & UFFD_USER_MODE_ONLY != 0;
38    if !user_mode_only {
39        security::check_task_capable(current_task, CAP_SYS_PTRACE)?;
40    }
41    let uff_handle = UserFaultFile::new(current_task, open_flags, user_mode_only)?;
42    current_task.add_file(uff_handle, fd_flags)
43}
44
45pub use sys_userfaultfd as sys_arch32_userfaultfd;
starnix_modules_userfaultfd/syscalls.rs

starnix_modules_userfaultfd/
syscalls.rs
