Messages in this thread | | | From | (H. Peter Anvin) | Subject | Re: UTF-8 practically vs. theoretically in the VFS API (was: Re: JFS default behavior) | Date | Wed, 18 Feb 2004 03:07:48 +0000 (UTC) |
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Followup to: <20040217163613.GA23499@mail.shareable.org> By author: Jamie Lokier <jamie@shareable.org> In newsgroup: linux.dev.kernel > > Linus Torvalds wrote: > > Which flies in the face of "Be strict in what you generate, be liberal in > > what you accept". A lot of the functions are _not_ willing to be liberal > > in what they accept. Which sometimes just makes the problem worse, for no > > good reason. > > Unicode specifies that a program claiming to read UTF-8 _must_ reject > malformed UTF-8. > > Ok, we can just ignore Unicode. :) > > But the reason they cite is security: when applications allow > malformed UTF-8 through, there's plenty of scope for security holes > due to multiple encodings of "/" and "." and "\0". > > This is a real problem: plenty of those Windows worms that attack web > servers get in by using multiple-escaped funny characters and > malformed UTF-8 to get past security checks for ".." and such. >
Actually, the kernel is 100% compliant in that respect.
The only byte sequences the kernel interpret:
00 2E 2E 2E 2F
.. and it correctly rejects (in the sense that it doesn't alias) any other possible byte stream that could be interpreted as the same sequences by a naïvely incorrect UTF-8 encoder.
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