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    SubjectRe: [patch 0/8] mount ownership and unprivileged mount syscall (v4)
    "Serge E. Hallyn" <> writes:

    > Quoting Miklos Szeredi (
    >> This patchset has now been bared to the "lowest common denominator"
    >> that everybody can agree on. Or at least there weren't any objections
    >> to this proposal.
    >> Andrew, please consider it for -mm.
    >> Thanks,
    >> Miklos
    >> ----
    >> v3 -> v4:
    >> - simplify interface as much as possible, now only a single option
    >> ("user=UID") is used to control everything
    >> - no longer allow/deny mounting based on file/directory permissions,
    >> that approach does not always make sense
    >> ----
    >> This patchset adds support for keeping mount ownership information in
    >> the kernel, and allow unprivileged mount(2) and umount(2) in certain
    >> cases.
    >> The mount owner has the following privileges:
    >> - unmount the owned mount
    >> - create a submount under the owned mount
    >> The sysadmin can set the owner explicitly on mount and remount. When
    >> an unprivileged user creates a mount, then the owner is automatically
    >> set to the user.
    >> The following use cases are envisioned:
    >> 1) Private namespace, with selected mounts owned by user.
    >> E.g. /home/$USER is a good candidate for allowing unpriv mounts and
    >> unmounts within.
    >> 2) Private namespace, with all mounts owned by user and having the
    >> "nosuid" flag. User can mount and umount anywhere within the
    >> namespace, but suid programs will not work.
    >> 3) Global namespace, with a designated directory, which is a mount
    >> owned by the user. E.g. /mnt/users/$USER is set up so that it is
    >> bind mounted onto itself, and set to be owned by $USER. The user
    >> can add/remove mounts only under this directory.
    >> The following extra security measures are taken for unprivileged
    >> mounts:
    >> - usermounts are limited by a sysctl tunable
    >> - force "nosuid,nodev" mount options on the created mount
    > Very nice. I like these semantics.
    > I'll try to rework my laptop in the next few days to use this patchset
    > as a test.

    Agreed. It appears the approach of adding owner ship information to
    mount points and using that to control what may happen with them
    in regards to mount/unmount is the only workable approach in the
    unix environment.

    Now to dig into the details and ensure that they are correct.

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      Last update: 2007-04-20 18:37    [W:0.027 / U:1.360 seconds]
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