scripts/extract-sys-certs.pl

   1 #!/usr/bin/env perl
   2 #
   3 use warnings;
   4 use strict;
   5 use Math::BigInt;
   6 use Fcntl "SEEK_SET";
   7
   8 die "Format: $0 [-s <systemmap-file>] <vmlinux-file> <keyring-file>\n"
   9     if ($#ARGV != 1 && $#ARGV != 3 ||
  10         $#ARGV == 3 && $ARGV[0] ne "-s");
  11
  12 my $sysmap = "";
  13 if ($#ARGV == 3) {
  14     shift;
  15     $sysmap = $ARGV[0];
  16     shift;
  17 }
  18
  19 my $vmlinux = $ARGV[0];
  20 my $keyring = $ARGV[1];
  21
  22 #
  23 # Parse the vmlinux section table
  24 #
  25 open FD, "objdump -h $vmlinux |" || die $vmlinux;
  26 my @lines = <FD>;
  27 close(FD) || die $vmlinux;
  28
  29 my @sections = ();
  30
  31 foreach my $line (@lines) {
  32     chomp($line);
  33     if ($line =~ /\s*([0-9]+)\s+(\S+)\s+([0-9a-f]+)\s+([0-9a-f]+)\s+([0-9a-f]+)\s+([0-9a-f]+)\s+2[*][*]([0-9]+)/
  34         ) {
  35         my $seg  = $1;
  36         my $name = $2;
  37         my $len  = Math::BigInt->new("0x" . $3);
  38         my $vma  = Math::BigInt->new("0x" . $4);
  39         my $lma  = Math::BigInt->new("0x" . $5);
  40         my $foff = Math::BigInt->new("0x" . $6);
  41         my $align = 2 ** $7;
  42
  43         push @sections, { name => $name,
  44                           vma => $vma,
  45                           len => $len,
  46                           foff => $foff };
  47     }
  48 }
  49
  50 print "Have $#sections sections\n";
  51
  52 #
  53 # Try and parse the vmlinux symbol table.  If the vmlinux file has been created
  54 # from a vmlinuz file with extract-vmlinux then the symbol table will be empty.
  55 #
  56 open FD, "nm $vmlinux 2>/dev/null |" || die $vmlinux;
  57 @lines = <FD>;
  58 close(FD) || die $vmlinux;
  59
  60 my %symbols = ();
  61 my $nr_symbols = 0;
  62
  63 sub parse_symbols(@) {
  64     foreach my $line (@_) {
  65         chomp($line);
  66         if ($line =~ /([0-9a-f]+)\s([a-zA-Z])\s(\S+)/
  67             ) {
  68             my $addr = "0x" . $1;
  69             my $type = $2;
  70             my $name = $3;
  71
  72             $symbols{$name} = $addr;
  73             $nr_symbols++;
  74         }
  75     }
  76 }
  77 parse_symbols(@lines);
  78
  79 if ($nr_symbols == 0 && $sysmap ne "") {
  80     print "No symbols in vmlinux, trying $sysmap\n";
  81
  82     open FD, "<$sysmap" || die $sysmap;
  83     @lines = <FD>;
  84     close(FD) || die $sysmap;
  85     parse_symbols(@lines);
  86 }
  87
  88 die "No symbols available\n"
  89     if ($nr_symbols == 0);
  90
  91 print "Have $nr_symbols symbols\n";
  92
  93 die "Can't find system certificate list"
  94     unless (exists($symbols{"__cert_list_start"}) &&
  95             exists($symbols{"system_certificate_list_size"}));
  96
  97 my $start = Math::BigInt->new($symbols{"__cert_list_start"});
  98 my $end;
  99 my $size;
 100 my $size_sym = Math::BigInt->new($symbols{"system_certificate_list_size"});
 101
 102 open FD, "<$vmlinux" || die $vmlinux;
 103 binmode(FD);
 104
 105 my $s = undef;
 106 foreach my $sec (@sections) {
 107     my $s_name = $sec->{name};
 108     my $s_vma = $sec->{vma};
 109     my $s_len = $sec->{len};
 110     my $s_foff = $sec->{foff};
 111     my $s_vend = $s_vma + $s_len;
 112
 113     next unless ($start >= $s_vma);
 114     next if ($start >= $s_vend);
 115
 116     die "Certificate list size was not found on the same section\n"
 117         if ($size_sym < $s_vma || $size_sym > $s_vend);
 118
 119     die "Cert object in multiple sections: ", $s_name, " and ", $s->{name}, "\n"
 120         if ($s);
 121
 122     my $size_off = $size_sym -$s_vma + $s_foff;
 123     my $packed;
 124     die $vmlinux if (!defined(sysseek(FD, $size_off, SEEK_SET)));
 125     sysread(FD, $packed, 8);
 126     $size = unpack 'L!', $packed;
 127     $end = $start + $size;
 128
 129     printf "Have %u bytes of certs at VMA 0x%x\n", $size, $start;
 130
 131     die "Cert object partially overflows section $s_name\n"
 132         if ($end > $s_vend);
 133
 134     $s = $sec;
 135 }
 136
 137 die "Cert object not inside a section\n"
 138     unless ($s);
 139
 140 print "Certificate list in section ", $s->{name}, "\n";
 141
 142 my $foff = $start - $s->{vma} + $s->{foff};
 143
 144 printf "Certificate list at file offset 0x%x\n", $foff;
 145
 146 die $vmlinux if (!defined(sysseek(FD, $foff, SEEK_SET)));
 147 my $buf = "";
 148 my $len = sysread(FD, $buf, $size);
 149 die "$vmlinux" if (!defined($len));
 150 die "Short read on $vmlinux\n" if ($len != $size);
 151 close(FD) || die $vmlinux;
 152
 153 open FD, ">$keyring" || die $keyring;
 154 binmode(FD);
 155 $len = syswrite(FD, $buf, $size);
 156 die "$keyring" if (!defined($len));
 157 die "Short write on $keyring\n" if ($len != $size);
 158 close(FD) || die $keyring;