Re: 2.6.15 Bug? New security model?

[Bernd Schubert <bernd-schubert@gmx.de>]

Privet!

> > > Yes, 2.6.13 now makes the same trouble. No difference with 2.6.15.3.
> > > I played with mount -o noattrs, this makes no difference with 2.6.13,
> > > but has some effects to 2.6.15.3. Creating files in /var/run is
> > > possible again, lsattr gives "lsattr: Inappropriate ioctl for device
> > > While reading flags on /var/run", but deleting files in /var/run is
> > > still impossible (still rather bad for the init-scripts).
>
> Is the filesystem in question old - could it be created initially in the
> reiserfs v3.5 format (used with 2.2.x kernels) and later converted to
> v3.6 (by mounting with the "conv" option)?

Well, I'm rather sure I created this filesystem in May 2001 after the Win2000 
partion manager selectively deleted all my ext2 partitions (I'm still very 
angry about MS). However, that time I already knew that v3.5 should not be 
used with NFS and I always used NFS a lot(my first mail to the reiser list 
was in early 2001 about a reiser v3.5 + nfs problem). I also used 
Slackware-8.0-pre that time and also just checked it, the mkreiserfs from 
slackware-8.0 has v3.6 as default. So really, its very unlikely that my 
current root partition ever had v3.5 on it.

>
> > Yes, that's what I thought.  There's still some backward logic in there.
> > noattrs vs. attrs triggers whether the code path that's patched in
> > 2.6.15.3 is taken.  I'll dig a bit more, but hopefully the reiserfs folks
> > can fix this for us.
>
> Here is a simple test case which reproduces the problem with a
> filesystem converted from v3.5:
>
> # dd if=/dev/zero of=tmp.img bs=1M count=100
> # mkreiserfs --format 3.5 -f tmp.img
> # mount -t reiserfs -o loop,conv tmp.img /mnt/disk/
> # umount /mnt/disk/
> # reiserfsck --clean-attributes tmp.img
> # mount -t reiserfs -o loop tmp.img /mnt/disk/
>
> At this point, I get obviously wrong attributes on /mnt/disk:
>
> # lsattr -d /mnt/disk/
> -----a--c---- /mnt/disk/
>
> BTW, this breaks even with kernels earlier than 2.6.15.2, if you also
> add the "attrs" options to the last mount command.
>
> Apparently the reiserfs attrs code has been broken for such converted
> filesystems for some time, but it could be enabled only with the "attrs"
> option, so people were not hitting this.  However, the following patch:
>
> http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=comm
>it;h=2949ccf9379678df66ecf2ca70ed4656159eacdd
>
> changed the logic to enable the "attrs" option on all filesystems which
> have the reiserfs_attrs_cleared flag.  But that patch was broken - it
> did not really set the option properly, so the attrs-related breakage
> did not became visible until yet another patch:
>
> http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=comm
>it;h=d35c602870ece3166cff3d25fbc687a7f707acf3
>
> which later made into 2.6.15.2, and caused problems for some people.

I already reverted the patch in 2.6.15.2 for some NFSv4 tests with 2.6.15, but 
of course, this is not the final solution. Neither for me, nor for the other 
thousands of reiserfs filesystems out there, that suddenly break beginning 
with 2.6.15.2.


>
> I have noticed that fs/reiserfs/inode.c:init_inode() does not initialize
> REISERFS_I(inode)->i_attrs and inode->i_flags (as done by
> sd_attrs_to_i_attrs()) in the branch for v1 stat data; maybe this causes
> the problem?

Please forgive me my missing knowledge about the internals of reiserfs, 
reiserfs doesn't have an inode for each file and directory as ext2, right?
Is there some way to detect if the inode was created on reiser3.5?

Thanks,
	Bernd

-- 
Bernd Schubert
PCI / Theoretische Chemie
Universität Heidelberg
INF 229
69120 Heidelberg

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