Skip site navigation (1)Skip section navigation (2)
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>

next in thread | previous in thread | raw e-mail | index | archive | help
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.
> 
> To Unsubscribe: send mail to majordomo@FreeBSD.org
> with "unsubscribe freebsd-arch" in the body of the message
> 


To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-arch" in the body of the message




Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.NEB.3.96L.1021014132336.56465H-100000>