[PATCH v4 5/6] add listmount(2) syscall
Christian Brauner
brauner at kernel.org
Wed Nov 8 16:23:43 UTC 2023
On Wed, Nov 08, 2023 at 09:20:28AM -0700, Jonathan Corbet wrote:
> Christian Brauner <brauner at kernel.org> writes:
>
> >> Why use struct __mount_arg (or struct mnt_id_req :) here rather than
> >> just passing in the mount ID directly? You don't use the request_mask
> >
> > Please see Arnd's detailed summary here:
> > https://lore.kernel.org/lkml/44631c05-6b8a-42dc-b37e-df6776baa5d4@app.fastmail.com
>
> Ah, makes sense, I'd missed that.
>
> Given this, though, it seems like maybe sys_listmount() should enforce
> that req->request_mask==0 ?
Good catch, it does now:
diff --git a/fs/namespace.c b/fs/namespace.c
index ae09321b0f72..21edddd75532 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -5030,6 +5030,8 @@ SYSCALL_DEFINE4(listmount, const struct mnt_id_req __user *, req,
if (copy_from_user(&kreq, req, sizeof(kreq)))
return -EFAULT;
+ if (kreq.request_mask != 0)
+ return -EINVAL;
mnt_id = kreq.mnt_id;
down_read(&namespace_sem);
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