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Date:   Fri, 23 Aug 2019 21:29:32 +0000
From:   Luis Chamberlain <mcgrof@kernel.org>
To:     Scott Branden <scott.branden@broadcom.com>
Cc:     Takashi Iwai <tiwai@suse.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        David Brown <david.brown@linaro.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Shuah Khan <shuah@kernel.org>, bjorn.andersson@linaro.org,
        Shuah Khan <skhan@linuxfoundation.org>,
        Arnd Bergmann <arnd@arndb.de>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        linux-fsdevel@vger.kernel.org,
        BCM Kernel Feedback <bcm-kernel-feedback-list@broadcom.com>,
        Olof Johansson <olof@lixom.net>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        Colin Ian King <colin.king@canonical.com>,
        Kees Cook <keescook@chromium.org>,
        linux-kselftest@vger.kernel.org, Mimi Zohar <zohar@linux.ibm.com>
Subject: Re: [PATCH 1/7] fs: introduce kernel_pread_file* support
Message-ID: <20190823212932.GY16384@42.do-not-panic.com>
References: <20190822192451.5983-1-scott.branden@broadcom.com>
 <20190822192451.5983-2-scott.branden@broadcom.com>
 <s5hsgpsqd49.wl-tiwai@suse.de>
 <5227a1bb-52e5-d547-2650-b06bee259012@broadcom.com>
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On Fri, Aug 23, 2019 at 12:55:30PM -0700, Scott Branden wrote:
> Hi Takashi
> 
> On 2019-08-23 5:29 a.m., Takashi Iwai wrote:
> > On Thu, 22 Aug 2019 21:24:45 +0200,
> > Scott Branden wrote:
> > > Add kernel_pread_file* support to kernel to allow for partial read
> > > of files with an offset into the file.  Existing kernel_read_file
> > > functions call new kernel_pread_file functions with offset=0 and
> > > flags=KERNEL_PREAD_FLAG_WHOLE.
> > Would this change passes the security check like ima?
> > I thought security_kernel_post_read_file() checks the whole content
> > for calculating the hash...
> 
> It passes the fw_run_tests.sh.? How do you test the firmware loader passes
> this security check?

Its not a security check per code, its an audit of the code, to ensure
that no new cases are not covered and its why I had CC'd Mimi. The
question lies in *if* the approach exposes a new interface which cannot
be attested. Its unclear to me if we can attest currently through
security modules the fallback interface, as there are not APIs with a
respective callback yet.

  Luis