LXR linux/scripts/extract-sys-certs.pl

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