1#!/usr/bin/perl
2
3#
4#//===----------------------------------------------------------------------===//
5#//
6#//                     The LLVM Compiler Infrastructure
7#//
8#// This file is dual licensed under the MIT and the University of Illinois Open
9#// Source Licenses. See LICENSE.txt for details.
10#//
11#//===----------------------------------------------------------------------===//
12#
13
14use strict;
15use warnings;
16
17use FindBin;
18use lib "$FindBin::Bin/lib";
19
20use tools;
21
22our $VERSION = "0.002";
23
24sub execstack($) {
25    my ( $file ) = @_;
26    my @output;
27    my @stack;
28    execute( [ "readelf", "-l", "-W", $file ], -stdout => \@output );
29    @stack = grep( $_ =~ m{\A\s*(?:GNU_)?STACK\s+}, @output );
30    if ( not @stack ) {
31        # Interpret missed "STACK" line as error.
32        runtime_error( "$file: No stack segment found; looks like stack would be executable." );
33    }; # if
34    if ( @stack > 1 ) {
35        runtime_error( "$file: More than one stack segment found.", "readelf output:", @output, "(eof)" );
36    }; # if
37    # Typical stack lines are:
38    # Linux* OS IA-32 architecture:
39    #    GNU_STACK      0x000000 0x00000000 0x00000000 0x00000 0x00000 RWE 0x4
40    # Linux* OS Intel(R) 64:
41    #    GNU_STACK      0x000000 0x0000000000000000 0x0000000000000000 0x000000 0x000000 RWE 0x8
42    if ( $stack[ 0 ] !~ m{\A\s*(?:GNU_)?STACK(?:\s+0x[0-9a-f]+){5}\s+([R ][W ][E ])\s+0x[0-9a-f]+\s*\z} ) {
43        runtime_error( "$file: Cannot parse stack segment line:", ">>> $stack[ 0 ]" );
44    }; # if
45    my $attrs = $1;
46    if ( $attrs =~ m{E} ) {
47        runtime_error( "$file: Stack is executable" );
48    }; # if
49}; # sub execstack
50
51get_options(
52);
53
54foreach my $file ( @ARGV ) {
55    execstack( $file );
56}; # foreach $file
57
58exit( 0 );
59
60__END__
61
62=pod
63
64=head1 NAME
65
66B<check-execstack.pl> -- Check whether stack is executable, issue an error if so.
67
68=head1 SYNOPSIS
69
70B<check-execstack.pl> I<optiion>... I<file>...
71
72=head1 DESCRIPTION
73
74The script checks whether stack of specified executable file, and issues error if stack is
75executable. If stack is not executable, the script exits silently with zero exit code.
76
77The script runs C<readelf> utility to get information about specified executable file. So, the
78script fails if C<readelf> is not available. Effectively it means the script works only on Linux* OS
79(and, probably, Intel(R) Many Integrated Core Architecture).
80
81=head1 OPTIONS
82
83=over
84
85=item Standard Options
86
87=over
88
89=item B<--doc>
90
91=item B<--manual>
92
93Print full help message and exit.
94
95=item B<--help>
96
97Print short help message and exit.
98
99=item B<--usage>
100
101Print very short usage message and exit.
102
103=item B<--verbose>
104
105Do print informational messages.
106
107=item B<--version>
108
109Print program version and exit.
110
111=item B<--quiet>
112
113Work quiet, do not print informational messages.
114
115=back
116
117=back
118
119=head1 ARGUMENTS
120
121=over
122
123=item I<file>
124
125A name of executable or shared object to check. Multiple files may be specified.
126
127=back
128
129=head1 EXAMPLES
130
131Check libiomp5.so library:
132
133    $ check-execstack.pl libiomp5.so
134
135=cut
136
137# end of file #
138
139