linux-kernel - Re: [PATCH 4/6] ext2: tighten restrictions on inode flags

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Message-ID: <e9e943910806120238k73736218k8aa34857497b348a@mail.gmail.com>
Date:	Thu, 12 Jun 2008 10:38:53 +0100
From:	"Duane Griffin" <duaneg@...da.com>
To:	"Andreas Dilger" <adilger@....com>
Cc:	akpm@...ux-foundation.org, linux-ext4@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/6] ext2: tighten restrictions on inode flags

2008/6/12 Andreas Dilger <adilger@....com>:
> On Jun 11, 2008  01:04 +0100, Duane Griffin wrote:
>> At the moment there are few restrictions on which flags may be set on which
>> inodes. Specifically DIRSYNC may only be set on directories and IMMUTABLE
>> and APPEND may not be set on links. Tighten that to disallow TOPDIR being
>> set on non-directories and SECRM, UNRM, COMPR, SYNC, DIRTY, COMPRBLK,
>> NOCOMP, ECOMPR, INDEX, JOURNAL_DATA and NOTAIL being set on anything but
>> regular files or directories.
>>
>> Introduce a flags masking function which masks flags based on mode and use
>> it during inode creation and when flags are set via the ioctl to facilitate
>> future consistency.
>
> This second set of patches is missing out on the presence of the
> "EXT2_FL_USER_MODIFIABLE" mask in ext2_ioctl(EXT2_IOC_SETFLAGS).  This is
> what prevents "unsettable" flags from being set from userspace.
>
> I don't have any objection to additional filtering to avoid setting the
> USER_MODIFIABLE flags on special files.

OK, thanks. I convinced myself that the patch wouldn't actually change
behaviour in the ioctl case, but thought it best to use it anyway for
consistency and to avoid future problems. I should probably have
mentioned that in the ChangeLog; I never know quite how exhaustive to
be in these things...

> Cheers, Andreas

Cheers,
Duane.

-- 
"I never could learn to drink that blood and call it wine" - Bob Dylan
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