scripts/extract-sys-certs.pl

   1 #!/usr/bin/env perl
   2 # SPDX-License-Identifier: GPL-2.0
   3 #
   4 use warnings;
   5 use strict;
   6 use Math::BigInt;
   7 use Fcntl "SEEK_SET";
   8
   9 die "Format: $0 [-s <systemmap-file>] <vmlinux-file> <keyring-file>\n"
  10     if ($#ARGV != 1 && $#ARGV != 3 ||
  11         $#ARGV == 3 && $ARGV[0] ne "-s");
  12
  13 my $sysmap = "";
  14 if ($#ARGV == 3) {
  15     shift;
  16     $sysmap = $ARGV[0];
  17     shift;
  18 }
  19
  20 my $vmlinux = $ARGV[0];
  21 my $keyring = $ARGV[1];
  22
  23 #
  24 # Parse the vmlinux section table
  25 #
  26 open FD, "objdump -h $vmlinux |" || die $vmlinux;
  27 my @lines = <FD>;
  28 close(FD) || die $vmlinux;
  29
  30 my @sections = ();
  31
  32 foreach my $line (@lines) {
  33     chomp($line);
  34     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]+)/
  35         ) {
  36         my $seg  = $1;
  37         my $name = $2;
  38         my $len  = Math::BigInt->new("0x" . $3);
  39         my $vma  = Math::BigInt->new("0x" . $4);
  40         my $lma  = Math::BigInt->new("0x" . $5);
  41         my $foff = Math::BigInt->new("0x" . $6);
  42         my $align = 2 ** $7;
  43
  44         push @sections, { name => $name,
  45                           vma => $vma,
  46                           len => $len,
  47                           foff => $foff };
  48     }
  49 }
  50
  51 print "Have $#sections sections\n";
  52
  53 #
  54 # Try and parse the vmlinux symbol table.  If the vmlinux file has been created
  55 # from a vmlinuz file with extract-vmlinux then the symbol table will be empty.
  56 #
  57 open FD, "nm $vmlinux 2>/dev/null |" || die $vmlinux;
  58 @lines = <FD>;
  59 close(FD) || die $vmlinux;
  60
  61 my %symbols = ();
  62 my $nr_symbols = 0;
  63
  64 sub parse_symbols(@) {
  65     foreach my $line (@_) {
  66         chomp($line);
  67         if ($line =~ /([0-9a-f]+)\s([a-zA-Z])\s(\S+)/
  68             ) {
  69             my $addr = "0x" . $1;
  70             my $type = $2;
  71             my $name = $3;
  72
  73             $symbols{$name} = $addr;
  74             $nr_symbols++;
  75         }
  76     }
  77 }
  78 parse_symbols(@lines);
  79
  80 if ($nr_symbols == 0 && $sysmap ne "") {
  81     print "No symbols in vmlinux, trying $sysmap\n";
  82
  83     open FD, "<$sysmap" || die $sysmap;
  84     @lines = <FD>;
  85     close(FD) || die $sysmap;
  86     parse_symbols(@lines);
  87 }
  88
  89 die "No symbols available\n"
  90     if ($nr_symbols == 0);
  91
  92 print "Have $nr_symbols symbols\n";
  93
  94 die "Can't find system certificate list"
  95     unless (exists($symbols{"__cert_list_start"}) &&
  96             exists($symbols{"system_certificate_list_size"}));
  97
  98 my $start = Math::BigInt->new($symbols{"__cert_list_start"});
  99 my $end;
 100 my $size;
 101 my $size_sym = Math::BigInt->new($symbols{"system_certificate_list_size"});
 102
 103 open FD, "<$vmlinux" || die $vmlinux;
 104 binmode(FD);
 105
 106 my $s = undef;
 107 foreach my $sec (@sections) {
 108     my $s_name = $sec->{name};
 109     my $s_vma = $sec->{vma};
 110     my $s_len = $sec->{len};
 111     my $s_foff = $sec->{foff};
 112     my $s_vend = $s_vma + $s_len;
 113
 114     next unless ($start >= $s_vma);
 115     next if ($start >= $s_vend);
 116
 117     die "Certificate list size was not found on the same section\n"
 118         if ($size_sym < $s_vma || $size_sym > $s_vend);
 119
 120     die "Cert object in multiple sections: ", $s_name, " and ", $s->{name}, "\n"
 121         if ($s);
 122
 123     my $size_off = $size_sym -$s_vma + $s_foff;
 124     my $packed;
 125     die $vmlinux if (!defined(sysseek(FD, $size_off, SEEK_SET)));
 126     sysread(FD, $packed, 8);
 127     $size = unpack 'L!', $packed;
 128     $end = $start + $size;
 129
 130     printf "Have %u bytes of certs at VMA 0x%x\n", $size, $start;
 131
 132     die "Cert object partially overflows section $s_name\n"
 133         if ($end > $s_vend);
 134
 135     $s = $sec;
 136 }
 137
 138 die "Cert object not inside a section\n"
 139     unless ($s);
 140
 141 print "Certificate list in section ", $s->{name}, "\n";
 142
 143 my $foff = $start - $s->{vma} + $s->{foff};
 144
 145 printf "Certificate list at file offset 0x%x\n", $foff;
 146
 147 die $vmlinux if (!defined(sysseek(FD, $foff, SEEK_SET)));
 148 my $buf = "";
 149 my $len = sysread(FD, $buf, $size);
 150 die "$vmlinux" if (!defined($len));
 151 die "Short read on $vmlinux\n" if ($len != $size);
 152 close(FD) || die $vmlinux;
 153
 154 open FD, ">$keyring" || die $keyring;
 155 binmode(FD);
 156 $len = syswrite(FD, $buf, $size);
 157 die "$keyring" if (!defined($len));
 158 die "Short write on $keyring\n" if ($len != $size);
 159 close(FD) || die $keyring;