linux-kernel - Re: [RFC PATCH] checkpatch: add shebang check to EXECUTE

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Date:   Mon, 12 Oct 2020 19:22:47 +0530
From:   Ujjwal Kumar <ujjwalkumar0501@...il.com>
To:     Joe Perches <joe@...ches.com>,
        Lukas Bulwahn <lukas.bulwahn@...il.com>
Cc:     linux-kernel-mentees@...ts.linuxfoundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] checkpatch: add shebang check to EXECUTE_PERMISSIONS

On 12/10/20 11:47 am, Joe Perches wrote:
> On Mon, 2020-10-12 at 11:19 +0530, Ujjwal Kumar wrote:
>> checkpatch.pl checks for invalid EXECUTE_PERMISSIONS on source
>> files. The script leverages filename extensions and its path in
>> the repository to decide whether to allow execute permissions on
>> the file or not.
>>
>> Based on current check conditions, a perl script file having
>> execute permissions, without '.pl' extension in its filename
>> and not belonging to 'scripts/' directory is reported as ERROR
>> which is a false-positive.
>>
>> Adding a shebang check along with current conditions will make
>> the check more generalised and improve checkpatch reports.
>> To do so, without breaking the core design decision of checkpatch,
>> we can fetch the first line from the patch itself and match it for
>> a shebang pattern.
>>
>> There can be cases where the first line is not part of the patch.
> 
> For instance: a patch that only changes permissions
> without changing any of the file content.
> 
>>
>> In that case there may be a false-positive report but in the end we
>> will have less false-positives as we will be handling some of the
>> unhandled cases.
> 
>> Signed-off-by: Ujjwal Kumar <ujjwalkumar0501@...il.com>
>> ---
>> Apologies, I forgot to include linux-kernel@...r.kernel.org so I'm
>> now resending.
>>
>>  scripts/checkpatch.pl | 19 +++++++++++++++++++
>>  1 file changed, 19 insertions(+)
>>
>> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> []
>> @@ -1795,6 +1795,23 @@ sub get_stat_here {
>>  	return $herectx;
>>  }
> 
> First some style trivia:
> 
>> +sub get_shebang {
>> +	my ($linenr, $realfile) = @_;
>> +	my $rawline = "";
>> +	my $shebang = "";
>> +
>> +	$rawline = raw_line($linenr, 3);
>> +	if (defined $rawline &&
>> +		$rawline =~ /^\@\@ -\d+(?:,\d+)? \+(\d+)(,(\d+))? \@\@/) {
> 
> alignment to open parenthesis please
> 
>> +		if (defined $1 && $1 == 1) {
>> +			$shebang = raw_line($linenr, 4);
>> +			$shebang = substr $shebang, 1;
> 
> parentheses around substr please.
> 
>> +		}
>> +	}
>> +
>> +	return $shebang;
>> +}
> 
> And some real notes:
> 
> $realfile isn't used in this function so there doesn't
> seem to be a reason to have it as an function argument.
> 
>> +
>>  sub cat_vet {
>>  	my ($vet) = @_;
>>  	my ($res, $coded);
>> @@ -2680,7 +2697,9 @@ sub process {
>>  # Check for incorrect file permissions
>>  		if ($line =~ /^new (file )?mode.*[7531]\d{0,2}$/) {
> 
> probably better here to use a capture group for the permissions
> 
> 		if ($line =~ /^new (?:file )?mode (\d+)$/) {
> 			my $mode = substr($1, -3);

This

> 
>>  			my $permhere = $here . "FILE: $realfile\n";
>> +			my $shebang = get_shebang($linenr, $realfile);
>>  			if ($realfile !~ m@...ipts/@ &&
> 
> Maybe remove the $realfile directory test as
> there are many source files that are not scripts
> in this directory and its subdirectories.

this

> 
>> +			    $shebang !~ /^#!\s*(\/\w)+.*/ &&
> 
> unnecessary capture group
> 
> and add
> 
> 			   $mode =~ /[1357]/ &&

this

> 
>>  			    $realfile !~ /\.(py|pl|awk|sh)$/) {
> 
> No need for a a capture group here either. (existing defect)

and this.

> 
>>  				ERROR("EXECUTE_PERMISSIONS",
>>  				      "do not set execute permissions for source files\n" . $permhere);
> 
> 
> 

Should these new changes go as a separate patch or can they be
included in the next iteration of this patch?



Thanks
Ujjwal Kumar