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    SubjectRe: [PATCH v3] vfs: new O_NODE open flag
    On Wed 2009-12-02 17:16:57, Miklos Szeredi wrote:
    > v2->v3 slightly updated patch description
    >
    > Thanks to Alan for the feedback. The main points raised were I think:
    >
    > 1) There's a security hole with dynamicly allocated devices if
    > permissions on new device are difference than on old device.
    >
    > The issue is valid, but also exists if hard links are created to
    > device nodes. udev already defends against this by setting
    > permissions on device to zero before unlinking it.

    Perhaps machine has /dev on separate filesystem, not writeable to
    users?

    Adding new security holes is bad...

    > 3) There's an alleged security hole (commonly referred to as "Pavel's
    > issue" :) with reopening for write (or truncating) a file desciptor
    > through /proc/P/fd for a file descriptor opened for read-only.
    >
    > This patch doens't change any of that except the file opened without
    > any permission can also be re-opened with increased permissions, as
    > long as i_mode allows. I think this is an othogonal issue and so this
    > patch doesn't deal with it.

    You just made the hole way more common and easier to exploit.

    > Comments? Any chance of this being accepted into -mm?

    With adding 2 new security problems?
    Pavel

    --
    (english) http://www.livejournal.com/~pavelmachek
    (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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