Re: [SECURITY] Re: PATCH: rm -rf and readdir bug in coreutils-6.7

[Mikulas Patocka]

> Mikulas Patocka <address@hidden> writes:
>
> > If POSIX specifies something that is unimplementable (unique stable
> > inode numbers) the question is why to rely on it?
>
> But it's easily implementable, if your file system was written with
> POSIX in mind.

And if someone else designed it --- like FAT or SMB?

> In many cases the POSIX folks had to decide whether to make
> concessions to non-Unix practice.  For example, should POSIX allow a
> distinction between text and binary files, which is pretty much a
> requirement for DOS-ish file systems?

This is not filesystem issue, DOS can work with files with '\n' newlines 
too.

> As a general rule, the POSIX standardizers decided to stick with the
> traditional Unix semantics when there was a clear clash with non-Unix
> systems.  Inode numbers is one of those cases; newline representation
> is another.
>
> > In other words: what utility should I use to *reliably* copy directory
> > tree on smb filesystem? (current cp will choke if it finds two
> > directories with the same ino).
>
> smbclient should be able to do it, no?  (Admittedly it might be a bit
> awkward, but that's often what happens when you start dealing with
> nonstandard systems.  :-)
>
> There are a lot of packages that will break (sometimes subtly) on file
> systems that lack stable file serial numbers: coreutils, diffutils,
> git, tar, the list goes on for quite a ways.  I'm afraid the only
> current answer to this problem is "don't do that then".
> (I'm quoting Linus Torvalds in <http://lkml.org/lkml/2005/4/8/236>.)

So tell users not to do it. How should they otherwise find?

The most scary thing is that these filesystems most-time work and break 
randomly, when inode numbers colide.

Would you really dare to accept a patch that prints
"cp: error, your filesystem is not posix compliant, to prevent possible 
data damage, coreutils refuses to operate on it?" on non-conforming 
filesystems? (AFS, SMB, CODA, FAT ...)

Coreutils 5 used to work (at least if nlink == 1 they didn't care about 
inode numbers), the new code in coreutils 6 to prevent directory loops 
breaks on non-posix filesysmtes.

Mikulas