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From: "Ahmed S. Darwish" <darwish.07@gmail.com>
To: "Adrian Bunk" <bunk@kernel.org>
Cc: "Kyle Moffett" <mrmacman_g4@mac.com>,
	"Casey Schaufler" <casey@schaufler-ca.com>,
	akpm@osdl.org, torvalds@osdl.org,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Smackv10: Smack rules grammar + their stateful parser
Date: Tue, 6 Nov 2007 14:23:36 +0200	[thread overview]
Message-ID: <1865922a0711060423ue81dbdct413b993e727f6f9@mail.gmail.com> (raw)
In-Reply-To: <20071106114738.GH26163@stusta.de>

On 11/6/07, Adrian Bunk <bunk@kernel.org> wrote:
> On Tue, Nov 06, 2007 at 01:34:05PM +0200, Ahmed S. Darwish wrote:
> > Hi,
> >
> > On Tue, Nov 06, 2007 at 09:56:51AM +0100, Adrian Bunk wrote:
> > > On Tue, Nov 06, 2007 at 03:26:12AM -0500, Kyle Moffett wrote:
> > > > On Nov 06, 2007, at 01:33:05, Adrian Bunk wrote:
> > > >> Can you limit this to 7bit ASCII and use isascii() somewhere?
> > > >>
> > > >> Otherwise I'd expect funny things to happen when you e.g. use isspace() on
> > > >> the UTF-8 encoded character ??.
> > > >
> > > > Actually, you don't need to.  You tell them it expects UTF-8 encoded
> > > > strings and be done with it.  All US-ASCII characters from 0 through 127
> > > > (IE: high bit clear) are exactly the same in UTF-8, and UTF-8 special
> > > > characters have the high bit set in all bytes.  Therefore you just assume
> > > > that anything with the high bit set is part of a word and you can handle
> > > > basic UTF-8.  (It doesn't work on special UTF-8 space characters like
> > > > nonbreaking space and similar, but handling those is significantly more
> > > > complicated).
> > >
> > > The documentations says:
> > > "Smack labels cannot contain unprintable characters or the "/" (slash)
> > >  character."
> > >
> > > What you propose might contain unprintable characters, and it might even
> > > be invalid UTF-8.
> >
> > As far as I understand the problem now, isspace() accepts the 0xa0
> > character which might collide with some of UTF-8 encoded characters
> > cause the high bit is set.
> >
> > I used "if (!isspace(c) && !isgraph(c)) return -EINVAL;" to test
> > rules' characters validity which seems not enough. I'll add !isascii(c)
> > in the condition and ask Casey to change the documentation to be
> > something like:
> >
> > Smack labels are represented in ASCII characters, they cannot contain
> > unprintable characters or the '/' (slash) character.
> >
> > and in write():
> > if (!isascii(c) return -EINVAL;
> > if (!isspace(c) && !isgraph(c)) return -EINVAL;
> >
> > This satisfy above customized labels rule, right ?
>
> It should work for all charsets you'll usually have to handle.
>

I admit I'm not experienced in such encoding stuff, but shouldn't the
ASCII and the ASCII-compatible UTF-8 encodings be enough for the
labels ?

> It would not work if someone would e.g. give you UTF-16 encoded strings,
> but I don't see this happening in practice.

Won't this complicate the code too much ?

-- 
Ahmed S. Darwish
Homepage: http://darwish.07.googlepages.com
Blog: http://darwish-07.blogspot.com

  reply	other threads:[~2007-11-06 12:23 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-11-02 20:50 [PATCH] Version 10 (2.6.24-rc1) Smack: Simplified Mandatory Access Control Kernel Casey Schaufler
2007-11-03 16:43 ` [PATCH] Smackv10: Smack rules grammar + their stateful parser Ahmed S. Darwish
2007-11-03 18:30   ` Kyle Moffett
2007-11-03 22:12     ` Ahmed S. Darwish
2007-11-04 12:28   ` Pavel Machek
2007-11-04 13:23     ` Ahmed S. Darwish
2007-11-04 16:37       ` Casey Schaufler
2007-11-05  9:41     ` Ahmed S. Darwish
2007-11-05 16:21       ` Linus Torvalds
2007-11-05 21:56         ` Tetsuo Handa
2007-11-06 10:00           ` Adrian Bunk
2007-11-06 12:27             ` Tetsuo Handa
2007-11-06 13:58               ` Adrian Bunk
2007-11-06 14:32                 ` Tetsuo Handa
2007-11-06 14:59                   ` Adrian Bunk
2007-11-06 15:27                     ` Tetsuo Handa
2007-11-06 22:42                       ` Adrian Bunk
2007-11-05 23:38         ` Ahmed S. Darwish
2007-11-06  8:06         ` Adrian Bunk
2007-11-06 15:39           ` Linus Torvalds
2007-11-06 23:00             ` Adrian Bunk
2007-11-06 23:08               ` Linus Torvalds
2007-11-07  0:07                 ` Adrian Bunk
2007-11-07  0:27                   ` Linus Torvalds
2007-11-07  0:43                     ` Adrian Bunk
2007-11-07  1:03                       ` Tetsuo Handa
2007-11-07  1:06                       ` Linus Torvalds
2007-11-07  1:59                         ` Adrian Bunk
2007-11-07  4:09                           ` Linus Torvalds
2007-11-07 15:08                           ` Alan Cox
2007-11-04 20:06   ` Ahmed S. Darwish
2007-11-05  0:56   ` [PATCH] Smackv10: Smack rules grammar + their stateful parser(2) Ahmed S. Darwish
2007-11-10 17:05     ` Jakob Oestergaard
2007-11-10 19:45       ` Ahmed S. Darwish
2007-11-11 12:44     ` Pavel Machek
2007-11-11 18:37       ` Ahmed S. Darwish
2007-11-06  6:33   ` [PATCH] Smackv10: Smack rules grammar + their stateful parser Adrian Bunk
2007-11-06  8:26     ` Kyle Moffett
2007-11-06  8:56       ` Adrian Bunk
2007-11-06 11:02         ` Alan Cox
2007-11-06 11:34         ` Ahmed S. Darwish
2007-11-06 11:47           ` Adrian Bunk
2007-11-06 12:23             ` Ahmed S. Darwish [this message]
2007-11-06 12:49               ` Kyle Moffett
2007-11-06 13:34                 ` Adrian Bunk
2007-11-06 14:05                   ` Ahmed S. Darwish
2007-11-06 14:10                     ` Adrian Bunk
2007-11-06 14:30                       ` Ahmed S. Darwish
2007-11-06 15:53                 ` Linus Torvalds
2007-11-07 10:56                   ` [PATCH] Fix isspace() and other ctype.h functions to ignore chars 128-255 Kyle Moffett

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