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

   1#!/usr/bin/env perl
   2# SPDX-License-Identifier: GPL-2.0
   3#
   4use warnings;
   5use strict;
   6use Math::BigInt;
   7use Fcntl "SEEK_SET";
   8
   9die "Format: $0 [-s <systemmap-file>] <vmlinux-file> <keyring-file>\n"
  10    if ($#ARGV != 1 && $#ARGV != 3 ||
  11        $#ARGV == 3 && $ARGV[0] ne "-s");
  12
  13my $sysmap = "";
  14if ($#ARGV == 3) {
  15    shift;
  16    $sysmap = $ARGV[0];
  17    shift;
  18}
  19
  20my $vmlinux = $ARGV[0];
  21my $keyring = $ARGV[1];
  22
  23#
  24# Parse the vmlinux section table
  25#
  26open FD, "objdump -h $vmlinux |" || die $vmlinux;
  27my @lines = <FD>;
  28close(FD) || die $vmlinux;
  29
  30my @sections = ();
  31
  32foreach 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
  51print "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#
  57open FD, "nm $vmlinux 2>/dev/null |" || die $vmlinux;
  58@lines = <FD>;
  59close(FD) || die $vmlinux;
  60
  61my %symbols = ();
  62my $nr_symbols = 0;
  63
  64sub 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            $nr_symbols++;
  75        }
  76    }
  77}
  78parse_symbols(@lines);
  79
  80if ($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 $sysmap;
  86    parse_symbols(@lines);
  87}
  88
  89die "No symbols available\n"
  90    if ($nr_symbols == 0);
  91
  92print "Have $nr_symbols symbols\n";
  93
  94die "Can't find system certificate list"
  95    unless (exists($symbols{"__cert_list_start"}) &&
  96            exists($symbols{"system_certificate_list_size"}));
  97
  98my $start = Math::BigInt->new($symbols{"__cert_list_start"});
  99my $end;
 100my $size;
 101my $size_sym = Math::BigInt->new($symbols{"system_certificate_list_size"});
 102
 103open FD, "<$vmlinux" || die $vmlinux;
 104binmode(FD);
 105
 106my $s = undef;
 107foreach 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 = $sec;
 136}
 137
 138die "Cert object not inside a section\n"
 139    unless ($s);
 140
 141print "Certificate list in section ", $s->{name}, "\n";
 142
 143my $foff = $start - $s->{vma} + $s->{foff};
 144
 145printf "Certificate list at file offset 0x%x\n", $foff;
 146
 147die $vmlinux if (!defined(sysseek(FD, $foff, SEEK_SET)));
 148my $buf = "";
 149my $len = sysread(FD, $buf, $size);
 150die "$vmlinux" if (!defined($len));
 151die "Short read on $vmlinux\n" if ($len != $size);
 152close(FD) || die $vmlinux;
 153
 154open FD, ">$keyring" || die $keyring;
 155binmode(FD);
 156$len = syswrite(FD, $buf, $size);
 157die "$keyring" if (!defined($len));
 158die "Short write on $keyring\n" if ($len != $size);
 159close(FD) || die $keyring;
 160