[PATCH RFC POC 23/50] file: open-code receive_fd()'s immediate install
From: Christian Brauner <brauner@kernel.org>
Date: 2026-09-15 11:34:17
Also in:
bpf, dri-devel, io-uring, kexec, kvm, linux-alpha, linux-arm-kernel, linux-arm-msm, linux-fsdevel, linux-gpio, linux-hyperv, linux-m68k, linux-mips, linux-mm, linux-sh, linux-um, linuxppc-dev, lkml, sparclinux, virtualization
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
receive_fd() cannot defer to syscall exit as SECCOMP_IOCTL_NOTIF_ADDFD installs into the target task and hands the number to the supervisor and IORING_OP_FIXED_FD_INSTALL runs from an io_uring op. Open-code the get_unused_fd_flags() + fd_install() it did through FD_PREPARE(). Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org> --- fs/file.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/fs/file.c b/fs/file.c
index 2b041b45f225..1f06d0c846c2 100644
--- a/fs/file.c
+++ b/fs/file.c@@ -1607,25 +1607,27 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags) */ int receive_fd(struct file *file, int __user *ufd, unsigned int o_flags) { - int error; + int fd, error; error = security_file_receive(file); if (error) return error; - FD_PREPARE(fdf, o_flags, file); - if (fdf.err) - return fdf.err; - get_file(file); + fd = get_unused_fd_flags(o_flags); + if (fd < 0) + return fd; if (ufd) { - error = put_user(fd_prepare_fd(fdf), ufd); - if (error) + error = put_user(fd, ufd); + if (error) { + put_unused_fd(fd); return error; + } } - __receive_sock(fd_prepare_file(fdf)); - return fd_publish(fdf); + __receive_sock(file); + fd_install(fd, get_file(file)); + return fd; } EXPORT_SYMBOL_GPL(receive_fd);
--
2.53.0