Re: [security]: kernel ioctl()'s

Jamie Lokier (lkd@tantalophile.demon.co.uk)
Fri, 2 Jul 1999 01:49:39 +0200


Chris Evans wrote:
> In the
> case of ext2, a user can easily get the kernel to emit copious
> ext2_warning messages.

This should be fixed...

> Is FIBMAP used by anything? It would seem to me to be offering users
> read access to internal filesystem structures - and as such should be
> restricted to root (CAP_SYS_ADMIN or something).

FIBMAP is used by bootloaders.

It can also be used to optimise file access at the user level --
arguably a dubious thing to do, I'll get back to you when I've done the
experiments. (Ordering inode access by number when you've a lot of
inodes to read is sometimes a big win, but I don't know if ordering
content reads through FIBMAP is a win yet).

Please don't restrict FIBMAP unless you've some better reason. But do
feel free to fix the messages.

-- Jamie

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