Hi.
On Tue, May 05, 2020 at 04:04:31PM +0200, Christian Brauner <christian.brauner@xxxxxxxxxx> wrote:
> -SYSCALL_DEFINE2(setns, int, fd, int, nstype)
> +SYSCALL_DEFINE2(setns, int, fd, int, flags)
> [...]
> - file = proc_ns_fget(fd);
> - if (IS_ERR(file))
> - return PTR_ERR(file);
> + int err = 0;
>
> - err = -EINVAL;
> - ns = get_proc_ns(file_inode(file));
> - if (nstype && (ns->ops->type != nstype))
> + file = fget(fd);
> + if (!file)
> + return -EBADF;
> +
> + if (proc_ns_file(file)) {
> + ns = get_proc_ns(file_inode(file));
> + if (flags && (ns->ops->type != flags))
> + err = -EINVAL;
> + flags = ns->ops->type;
> + } else if (pidfd_pid(file)) {
> + err = check_setns_flags(flags);
> + } else {
> + err = -EBADF;
> + }
> + if (err)
> goto out;
>
> - err = prepare_nsset(ns->ops->type, &nsset);
> + err = prepare_nsset(flags, &nsset);
> if (err)
> goto out;
This modification changed the returned error when a valid file
descriptor is passed but it doesn't represent a namespace (nor pidfd).
The error is now EBADF although originally and per man page it
was/should be EINVAL.
A change like below would restore it, however, I see it may be less
consistent with other pidfd calls(?), then I'd suggest updating the
manpage to capture this.
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -531,7 +531,7 @@ SYSCALL_DEFINE2(setns, int, fd, int, flags)
} else if (!IS_ERR(pidfd_pid(file))) {
err = check_setns_flags(flags);
} else {
- err = -EBADF;
+ err = -EINVAL;
}
if (err)
goto out;
I noticed this breaks systemd self tests [1].
Regards,
Michal
[1] https://github.com/systemd/systemd/blob/a1ba8c5b71164665ccb53c9cec384e5eef7d3689/src/test/test-seccomp.c#L246
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