On 11/6/07, Adrian Bunk <[EMAIL PROTECTED]> 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 - To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
