linux-ext4 - Re: [PATCH v4 1/2] ext4: fix setattr project check upon fssetxattr ioctl

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Message-ID: <20181003143405.GA4555@thunk.org>
Date:   Wed, 3 Oct 2018 10:34:05 -0400
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Wang Shilong <wangshilong1991@...il.com>
Cc:     linux-ext4@...r.kernel.org, dchinner@...hat.com, adilger@...ger.ca,
        wshilong@....com
Subject: Re: [PATCH v4 1/2] ext4: fix setattr project check upon fssetxattr
 ioctl

On Tue, Sep 18, 2018 at 05:15:29PM +0900, Wang Shilong wrote:
> From: Wang Shilong <wangshilong1991@...il.com>
> 
> Currently, project quota could be changed by fssetxattr
> ioctl, and existed permission check inode_owner_or_capable()
> is obviously not enough, just think that common users could
> change project id of file, that could make users to
> break project quota easily.
> 
> This patch try to follow same regular of xfs project
> quota:
> 
> "Project Quota ID state is only allowed to change from
> within the init namespace. Enforce that restriction only
> if we are trying to change the quota ID state.
> Everything else is allowed in user namespaces."
> 
> Besides that, check and set project id'state should
> be an atomic operation, protect whole operation with
> inode lock, ext4_ioctl_setproject() is only used for
> ioctl EXT4_IOC_FSSETXATTR, we have held mnt_want_write_file()
> before ext4_ioctl_setflags(), and ext4_ioctl_setproject()
> is called after ext4_ioctl_setflags(), we could share
> codes, so remove it inside ext4_ioctl_setproject().
> 
> Signed-off-by: Wang Shilong <wshilong@....com>
> Reviewed-by: Andreas Dilger <adilger@...ger.ca>

Applied, thanks.

					- Ted