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From: Scott Branden <scott.branden@broadcom.com>
To: Mimi Zohar <zohar@kernel.org>,
	Luis Chamberlain <mcgrof@kernel.org>,
	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>
Cc: "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>, Takashi Iwai <tiwai@suse.de>,
	linux-kselftest@vger.kernel.org, Andy Gross <agross@kernel.org>,
	linux-security-module <linux-security-module@vger.kernel.org>,
	linux-integrity <linux-integrity@vger.kernel.org>
Subject: Re: [PATCH v5 1/7] fs: introduce kernel_pread_file* support
Date: Wed, 13 May 2020 11:57:09 -0700	[thread overview]
Message-ID: <104a1eea-6b55-d857-04b9-d13aed9a36fd@broadcom.com> (raw)
In-Reply-To: <0e6b5f65-8c61-b02e-7d35-b4ae52aebcf3@broadcom.com>



On 2020-05-13 11:53 a.m., Scott Branden wrote:
> Hi Mimi,
>
> On 2020-05-13 11:39 a.m., Mimi Zohar wrote:
>> [Cc'ing linux-security-module, linux-integrity]
>>
>> On Thu, 2020-05-07 at 17:27 -0700, 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.
>>>
>>> Signed-off-by: Scott Branden <scott.branden@broadcom.com>
>>> ---
>> <snip>
>>
>>> @@ -941,14 +955,16 @@ int kernel_read_file(struct file *file, void 
>>> **buf, loff_t *size,
> The checkpatch shows this as kernel_read_file when it is actually the 
> new function kernel_pread_file.
typo: "checkpatch" should be "patch diff"
> Please see the call to kernel_pread_file from kernel_read_file in the 
> complete patch rather this snippet.
>>>             if (bytes == 0)
>>>               break;
>>> +
>>> +        buf_pos += bytes;
>>>       }
>>>   -    if (pos != i_size) {
>>> +    if (pos != read_end) {
>>>           ret = -EIO;
>>>           goto out_free;
>>>       }
>>>   -    ret = security_kernel_post_read_file(file, *buf, i_size, id);
>>> +    ret = security_kernel_post_read_file(file, *buf, alloc_size, id);
>>>       if (!ret)
>>>           *size = pos;
>> Prior to the patch set that introduced this security hook, firmware
>> would be read twice, once for measuring/appraising the firmware and
>> again reading the file contents into memory.  Partial reads will break
>> both IMA's measuring the file and appraising the file signatures.
> The partial file read support is needed for request_firmware_into_buf 
> from drivers.  The EXPORT_SYMBOL_GPL is being removed so that
> there can be no abuse of the partial file read support.  Such file 
> integrity checks are not needed for this use case.  The partial file 
> (firmware image) is actually downloaded in portions and verified on 
> the device it is loaded to.
>
> Regards,
>  Scott


  reply	other threads:[~2020-05-13 18:57 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-08  0:27 [PATCH v5 0/7] firmware: add partial read support in request_firmware_into_buf Scott Branden
2020-05-08  0:27 ` [PATCH v5 1/7] fs: introduce kernel_pread_file* support Scott Branden
2020-05-13  0:27   ` Luis Chamberlain
2020-05-13  6:23     ` Scott Branden
2020-05-13  6:51       ` Greg Kroah-Hartman
2020-05-13  8:16         ` Scott Branden
2020-05-13 18:39   ` Mimi Zohar
2020-05-13 18:53     ` Scott Branden
2020-05-13 18:57       ` Scott Branden [this message]
2020-05-13 19:03       ` Mimi Zohar
2020-05-13 19:18         ` Scott Branden
2020-05-13 19:39           ` Mimi Zohar
2020-05-13 19:41             ` Scott Branden
2020-05-13 21:20               ` Mimi Zohar
2020-05-13 21:28                 ` Luis Chamberlain
2020-05-13 22:12                   ` Mimi Zohar
2020-05-13 22:48                     ` Scott Branden
2020-05-13 23:00                       ` Mimi Zohar
2020-05-13 23:34                         ` Kees Cook
2020-05-13 23:58                           ` Mimi Zohar
2020-05-08  0:27 ` [PATCH v5 2/7] firmware: add offset to request_firmware_into_buf Scott Branden
2020-05-13  0:33   ` Luis Chamberlain
2020-05-13 18:35     ` Scott Branden
2020-05-15 20:44       ` Luis Chamberlain
2020-05-08  0:27 ` [PATCH v5 3/7] test_firmware: add partial read support for request_firmware_into_buf Scott Branden
2020-05-13  0:35   ` Luis Chamberlain
2020-05-08  0:27 ` [PATCH v5 4/7] firmware: test partial file reads of request_firmware_into_buf Scott Branden
2020-05-08  0:27 ` [PATCH v5 5/7] bcm-vk: add bcm_vk UAPI Scott Branden
2020-05-08  0:27 ` [PATCH v5 7/7] MAINTAINERS: bcm-vk: add maintainer for Broadcom VK Driver Scott Branden
     [not found] ` <20200508002739.19360-7-scott.branden@broadcom.com>
2020-05-13  0:38   ` [PATCH v5 6/7] misc: bcm-vk: add Broadcom VK driver Luis Chamberlain
2020-05-13  6:31     ` Scott Branden
2020-05-13  6:50       ` Greg Kroah-Hartman
2020-05-13 12:30         ` Luis Chamberlain
2020-05-13 18:39           ` Scott Branden
2020-05-13 16:23 ` [PATCH v5 0/7] firmware: add partial read support in request_firmware_into_buf Mimi Zohar
2020-05-15 20:47   ` Luis Chamberlain
2020-05-15 23:28     ` Scott Branden
2020-05-16  1:05       ` Luis Chamberlain

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