linux-kernel - Re: [PATCH 05/13] fs: check FMODE_WRITE in __kernel

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Date:   Mon, 15 Jun 2020 15:48:04 +0200
From:   Christoph Hellwig <hch@....de>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Christoph Hellwig <hch@....de>, Al Viro <viro@...iv.linux.org.uk>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Ian Kent <raven@...maw.net>,
        David Howells <dhowells@...hat.com>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        netfilter-devel@...r.kernel.org
Subject: Re: [PATCH 05/13] fs: check FMODE_WRITE in __kernel_write

On Mon, Jun 15, 2020 at 05:34:39AM -0700, Matthew Wilcox wrote:
> On Mon, Jun 15, 2020 at 02:12:49PM +0200, Christoph Hellwig wrote:
> > We still need to check if the fѕ is open write, even for the low-level
> > helper.
> 
> Do we need the analogous check for FMODE_READ in the __kernel_read()
> patch?

Yes, we should probably grow it.  Hoping that none of the caller
actually wants to mess with files not open for reading as some of them
are rather dodgy.