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    SubjectRe: [Fireflier-devel] Re: [RESEND][RFC][PATCH 2/7] implementation of LSM hooks
    Date
    On Tuesday 18 April 2006 22:50, Arjan van de Ven wrote:
    >
    > I would suspect that the "filename" thing will be the biggest achilles
    > heel...
    > after all what does filename mean in a linux world with
    > * hardlinks
    > * chroot
    > * namespaces
    > * bind mounts
    > * unlink of open files
    > * fd passing over unix sockets
    > * relative pathnames
    > * multiple threads (where one can unlink+replace file while the other is
    > in the validation code)

    FYI fireflier v1.1.x created rules based on filenames.
    In the current version we intended to use mountpoint+inode to identify
    programs. This reduces the potential problems from your list to: fd passing.

    Can't AppArmor use inodes in addition to filenames to implement its rules?
    The user could still make its choice based on a "filename" (in an interactive
    userspace program), but by storing additional info along with the filename in
    the rules it would at least uniquely identify the program.
    (P.S.: I don't know how apparmor works, so what i said might not be directly
    applicable).

    Note, that since fireflier is going to use SELinux (as soon as I get the
    policy done) program identification isn't shouldn't be a problem for
    fireflier, but we still have two alternatives:

    - use extended attributes to label files, using selinux's setfiles. Most
    secure option IMHO
    (BTW can SELinux be told to use another xattr instead of security.selinux?
    Purpose: having multiple policies, and switching between them without the
    need to relabel, i.e. switching between a distro-provided policy/ a custom
    policy/ a fireflier generated policy)

    - store rules based on mountpoint+inode+program hash/checksum, and then get
    selinux to label files according to this. Not sure how to do this, and if it
    is worth at all


    Cheers,
    Edwin
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