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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Mon, 16 Nov 2020 09:37:32 -0800
Message-ID: <CAHk-=wiso=-Fhe2m042CfBNUGhoVB1Pry14DF64uUgztHVOW0g@mail.gmail.com>
Subject: Re: [RESEND][PATCH] ima: Set and clear FMODE_CAN_READ in ima_calc_file_hash()
To:     Mimi Zohar <zohar@linux.ibm.com>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Roberto Sassu <roberto.sassu@huawei.com>,
        "linux-integrity@vger.kernel.org" <linux-integrity@vger.kernel.org>,
        "linux-security-module@vger.kernel.org" 
        <linux-security-module@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Silviu Vlasceanu <Silviu.Vlasceanu@huawei.com>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
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On Mon, Nov 16, 2020 at 8:47 AM Mimi Zohar <zohar@linux.ibm.com> wrote:
>
> This discussion seems to be going down the path of requiring an IMA
> filesystem hook for reading the file, again.  That solution was
> rejected, not by me.  What is new this time?

You can't read a non-read-opened file. Not even IMA can.

So don't do that then.

IMA is doing something wrong. Why would you ever read a file that can't be read?

Fix whatever "open" function instead of trying to work around the fact
that you opened it wrong.

             Linus