Thread (65 messages) 65 messages, 9 authors, 2019-06-17

Re: [PATCH 3/7] vfs: Add a mount-notification facility

From: David Howells <dhowells@redhat.com>
Date: 2019-05-29 11:01:07
Also in: keyrings, linux-api, linux-block, linux-fsdevel, lkml

Jann Horn [off-list ref] wrote:
quoted
+void post_mount_notification(struct mount *changed,
+                            struct mount_notification *notify)
+{
+       const struct cred *cred = current_cred();
This current_cred() looks bogus to me. Can't mount topology changes
come from all sorts of places? For example, umount_mnt() from
umount_tree() from dissolve_on_fput() from __fput(), which could
happen pretty much anywhere depending on where the last reference gets
dropped?
IIRC, that's what Casey argued is the right thing to do from a security PoV.
Casey?

Maybe I should pass in NULL creds in the case that an event is being generated
because an object is being destroyed due to the last usage[*] being removed.

 [*] Usage, not ref - Superblocks are a bit weird in their accounting.

David
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