Date: Mon, 14 Oct 2002 13:27:57 -0400 (EDT) From: Robert Watson <rwatson@freebsd.org> To: "Vladimir B. Grebenschikov,Moscow,408-7227,123-4567,Some-info" <vova@express.ru> Cc: freebsd-arch@freebsd.org, freebsd-current@freebsd.org Subject: Re: short uid/gid Message-ID: <Pine.NEB.3.96L.1021014132336.56465H-100000@fledge.watson.org> In-Reply-To: <E180zjq-000OrL-00@vbook.express.ru>
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Yeah, this is a Known Problem, and it's quite unfortunate, actually. I
looked at trying to solve it -- changing the types respectively to uid_t,
gid_t, and mode_t, but it involved a lot of ABI munging because the
structures are shared between the userland interface and the kernel
implementation. The result is that any change in the kernel structure
really requires you to break out the user structures from the kernel
structure, which requires a lot of work. Also, ipc_perm is shared between
all three SysVIPC services, and to compound things, there are already
ofoo() interfaces for older versions of the structures. My belief is that
seperating the user and kernel structures is really necessary -- making a
kipc_perm, etc, so we can better support fine-grained locking and
extensible security. However, someone has to do the grunt work, and last
time I tried, I spent several days and only made a bit of progress. If
you want to give a first pass at breaking out the user and kernel
structures and send a patch, I'll be happy to work with you to get it
integrated. I think the steps are:
(1) Divorce user and kernel structures for all of the SysVIPC interfaces,
and provide functions to map between them as necessary.
(2) Remove the original compatibility interfaces left over from eons ago
(and figure out how many eons ago so we know what ABIs we're finally
removing).
(3) Define new userland versions of necessary structures and create a new
set of ofoo() and foo() interfaces based on the change.
(4) Go back through and dribble the kernel structures with new toys, such
as 'struct label', etc.
Robert N M Watson FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org Network Associates Laboratories
On Mon, 14 Oct 2002, Vladimir B. Grebenschikov,Moscow,408-7227,123-4567,Some-info wrote:
>
> Hi
>
> I have found that SysVIPC functions uses structure with short uid/gid types.
>
> What is valid solution ?
>
> Change types to uid_t/gid_t (but this will broke binary compatibility)
> Change syscalls to old_* and add new with "right" structures,
> or something else ?
>
> struct ipc_perm {
> ushort cuid; /* creator user id */
> ushort cgid; /* creator group id */
> ushort uid; /* user id */
> ushort gid; /* group id */
> ushort mode; /* r/w permission */
> ushort seq; /* sequence # (to generate unique msg/sem/shm id) */
> key_t key; /* user specified msg/sem/shm key */
> };
>
> --
> Vladimir B. Grebenschikov
> vova@sw.ru, SWsoft, Inc.
>
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