Re: [PATCH] new syscall: flink

[daw@mozart.cs.berkeley.edu (David Wagner)]

Clayton Weaver wrote:
>Once a process unlinks the last directory entry referencing a particular
>inode that it has an
>open fd for and then passes the open fd to some other process
>(regardless of exactly how it does that), it seems to me that it has
>conceded any interest in the previous security constraints associated
>with that inode or with the recently
>unlinked last directory entry for it.

Huh?  That's not the Unix model.  If I pass you a read-only file
descriptor, you're not supposed to be able to get write access to
the fd.  If you can, that's a security hole.  This is true whether
the fd refers to an inode still linked into the filesystem or not.

>The cases with potential security implications are all in the context of
>flink()ing to an open fd for an inode that still corresponds to at least
>one directory entry.

No, that's not correct.