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    SubjectRe: [PATCH 0/6] File Sealing & memfd_create()
    On Thu 2014-04-10 13:37:26, Andy Lutomirski wrote:
    > On Thu, Apr 10, 2014 at 1:32 PM, Theodore Ts'o <tytso@mit.edu> wrote:
    > > On Thu, Apr 10, 2014 at 12:14:27PM -0700, Andy Lutomirski wrote:
    > >>
    > >> This is the second time in a week that someone has asked for a way to
    > >> have a struct file (or struct inode or whatever) that can't be reopened
    > >> through /proc/pid/fd. This should be quite easy to implement as a
    > >> separate feature.
    > >
    > > What I suggested on a different thread was to add the following new
    > > file descriptor flags, to join FD_CLOEXEC, which would be maniuplated
    > > using the F_GETFD and F_SETFD fcntl commands:
    > >
    > > FD_NOPROCFS disallow being able to open the inode via /proc/<pid>/fd
    > >
    > > FD_NOPASSFD disallow being able to pass the fd via a unix domain socket
    > >
    > > FD_LOCKFLAGS if this bit is set, disallow any further changes of FD_CLOEXEC,
    > > FD_NOPROCFS, FD_NOPASSFD, and FD_LOCKFLAGS flags.
    > >
    > > Regardless of what else we might need to meet the use case for the
    > > proposed File Sealing API, I think this is a useful feature that could
    > > be used in many other contexts besides just the proposed
    > > memfd_create() use case.
    >
    > It occurs to me that, before going nuts with these kinds of flags, it
    > may pay to just try to fix the /proc/self/fd issue for real -- we
    > could just make open("/proc/self/fd/3", O_RDWR) fail if fd 3 is
    > read-only. That may be enough for the file sealing thing.

    Yes please.

    Current behaviour is very unexpected, and unexpected behaviour in
    security area is normally called "security hole".

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


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