convert setns(2) to fdget()/fdput()

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index a487ff24129b8ea5f4c343eade407dae82fc4f52..80d9c6d77a452648045c7dfd21e375ca01b46a3c 100644 (file)
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -545,21 +545,20 @@ static void commit_nsset(struct nsset *nsset)
 
 SYSCALL_DEFINE2(setns, int, fd, int, flags)
 {
-       struct file *file;
+       struct fd f = fdget(fd);
        struct ns_common *ns = NULL;
        struct nsset nsset = {};
        int err = 0;
 
-       file = fget(fd);
-       if (!file)
+       if (!f.file)
                return -EBADF;
 
-       if (proc_ns_file(file)) {
-               ns = get_proc_ns(file_inode(file));
+       if (proc_ns_file(f.file)) {
+               ns = get_proc_ns(file_inode(f.file));
                if (flags && (ns->ops->type != flags))
                        err = -EINVAL;
                flags = ns->ops->type;
-       } else if (!IS_ERR(pidfd_pid(file))) {
+       } else if (!IS_ERR(pidfd_pid(f.file))) {
                err = check_setns_flags(flags);
        } else {
                err = -EINVAL;
@@ -571,17 +570,17 @@ SYSCALL_DEFINE2(setns, int, fd, int, flags)
        if (err)
                goto out;
 
-       if (proc_ns_file(file))
+       if (proc_ns_file(f.file))
                err = validate_ns(&nsset, ns);
        else
-               err = validate_nsset(&nsset, file->private_data);
+               err = validate_nsset(&nsset, f.file->private_data);
        if (!err) {
                commit_nsset(&nsset);
                perf_event_namespaces(current);
        }
        put_nsset(&nsset);
 out:
-       fput(file);
+       fdput(f);
        return err;
 }