linux-kernel - Re: [PATCH v2] scripts: headers_install: Exit with error on config leak

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Message-ID: <2407804b-d5eb-7de3-c639-add3132d39b6@codeaurora.org>
Date:   Tue, 5 May 2020 18:45:51 -0700
From:   Siddharth Gupta <sidgup@...eaurora.org>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     Sam Ravnborg <sam@...nborg.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] scripts: headers_install: Exit with error on config
 leak


On 5/4/2020 12:18 AM, Masahiro Yamada wrote:
> On Sun, May 3, 2020 at 12:29 PM Siddharth Gupta <sidgup@...eaurora.org> wrote:
>> Misuse of CONFIG_* in UAPI headers should result in an error as it exposes
>> configuration of different targets to userspace.
>
> Sorry, I missed to point out this.
>
> This statement is not precious; it does not expose the kernel
> configuration at all.
>
> include/generated/autoconf.h is not available from userspace.
> So, all the CONFIG options are undefined.
>
> Could you reword the commit somehow?
>
Sure. I just meant that if a CONFIG_* is present in the UAPI header it 
can be set in a
userspace application that includes the header to manipulate the control 
flow in a
kernel that might support multiple targets.

I'll update the commit text and send out an updated patch.

Thanks,
Siddharth

>
>
>
>> Signed-off-by: Siddharth Gupta <sidgup@...eaurora.org>
>> ---
>>   scripts/headers_install.sh | 11 ++++++-----
>>   1 file changed, 6 insertions(+), 5 deletions(-)
>>
>> diff --git a/scripts/headers_install.sh b/scripts/headers_install.sh
>> index a07668a..94a8335 100755
>> --- a/scripts/headers_install.sh
>> +++ b/scripts/headers_install.sh
>> @@ -64,7 +64,7 @@ configs=$(sed -e '
>>          d
>>   ' $OUTFILE)
>>
>> -# The entries in the following list are not warned.
>> +# The entries in the following list do not result in an error.
>>   # Please do not add a new entry. This list is only for existing ones.
>>   # The list will be reduced gradually, and deleted eventually. (hopefully)
>>   #
>> @@ -98,18 +98,19 @@ include/uapi/linux/raw.h:CONFIG_MAX_RAW_DEVS
>>
>>   for c in $configs
>>   do
>> -       warn=1
>> +       leak_error=1
>>
>>          for ignore in $config_leak_ignores
>>          do
>>                  if echo "$INFILE:$c" | grep -q "$ignore$"; then
>> -                       warn=
>> +                       leak_error=
>>                          break
>>                  fi
>>          done
>>
>> -       if [ "$warn" = 1 ]; then
>> -               echo "warning: $INFILE: leak $c to user-space" >&2
>> +       if [ "$leak_error" = 1 ]; then
>> +               echo "error: $INFILE: leak $c to user-space" >&2
>> +               exit 1
>>          fi
>>   done
>>
>> --
>> Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
>> a Linux Foundation Collaborative Project
>
>