KEYS: Provide a script to extract the sys cert list from a vmlinux file

#!/usr/bin/perl -w

#

use strict;

use Math::BigInt;

use Fcntl "SEEK_SET";

die "Format: $0 [-s <systemmap-file>] <vmlinux-file> <keyring-file>\n"

    if ($#ARGV != 1 && $#ARGV != 3 ||

	$#ARGV == 3 && $ARGV[0] ne "-s");

my $sysmap = "";

if ($#ARGV == 3) {

    shift;

    $sysmap = $ARGV[0];

    shift;

}

my $vmlinux = $ARGV[0];

my $keyring = $ARGV[1];

#

# Parse the vmlinux section table

#

open FD, "objdump -h $vmlinux |" || die $vmlinux;

my @lines = <FD>;

close(FD) || die $vmlinux;

my @sections = ();

foreach my $line (@lines) {

    chomp($line);

    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]+)/

	) {

	my $seg  = $1;

	my $name = $2;

	my $len  = Math::BigInt->new("0x" . $3);

	my $vma  = Math::BigInt->new("0x" . $4);

	my $lma  = Math::BigInt->new("0x" . $5);

	my $foff = Math::BigInt->new("0x" . $6);

	my $align = 2 ** $7;

	push @sections, { name => $name,

			  vma => $vma,

			  len => $len,

			  foff => $foff };

    }

}

print "Have $#sections sections\n";

#

# Try and parse the vmlinux symbol table.  If the vmlinux file has been created

# from a vmlinuz file with extract-vmlinux then the symbol table will be empty.

#

open FD, "nm $vmlinux 2>/dev/null |" || die $vmlinux;

@lines = <FD>;

close(FD) || die $vmlinux;

my %symbols = ();

my $nr_symbols = 0;

sub parse_symbols(@) {

    foreach my $line (@_) {

	chomp($line);

	if ($line =~ /([0-9a-f]+)\s([a-zA-Z])\s(\S+)/

	    ) {

	    my $addr = "0x" . $1;

	    my $type = $2;

	    my $name = $3;

	    $symbols{$name} = $addr;

	    $nr_symbols++;

	}

    }

}

parse_symbols(@lines);

if ($nr_symbols == 0 && $sysmap ne "") {

    print "No symbols in vmlinux, trying $sysmap\n";

    open FD, "<$sysmap" || die $sysmap;

    @lines = <FD>;

    close(FD) || die $sysmap;

    parse_symbols(@lines);

}

die "No symbols available\n"

    if ($nr_symbols == 0);

print "Have $nr_symbols symbols\n";

die "Can't find system certificate list"

    unless (exists($symbols{"__cert_list_start"}) &&

	    exists($symbols{"__cert_list_end"}));

my $start = Math::BigInt->new($symbols{"__cert_list_start"});

my $end = Math::BigInt->new($symbols{"__cert_list_end"});

my $size = $end - $start;

printf "Have %u bytes of certs at VMA 0x%x\n", $size, $start;

my $s = undef;

foreach my $sec (@sections) {

    my $s_name = $sec->{name};

    my $s_vma = $sec->{vma};

    my $s_len = $sec->{len};

    my $s_foff = $sec->{foff};

    my $s_vend = $s_vma + $s_len;

    next unless ($start >= $s_vma);

    next if ($start >= $s_vend);

    die "Cert object partially overflows section $s_name\n"

	if ($end > $s_vend);

    die "Cert object in multiple sections: ", $s_name, " and ", $s->{name}, "\n"

	if ($s);

    $s = $sec;

}

die "Cert object not inside a section\n"

    unless ($s);

print "Certificate list in section ", $s->{name}, "\n";

my $foff = $start - $s->{vma} + $s->{foff};

printf "Certificate list at file offset 0x%x\n", $foff;

open FD, "<$vmlinux" || die $vmlinux;

binmode(FD);

die $vmlinux if (!defined(sysseek(FD, $foff, SEEK_SET)));

my $buf = "";

my $len = sysread(FD, $buf, $size);

die "$vmlinux" if (!defined($len));

die "Short read on $vmlinux\n" if ($len != $size);

close(FD) || die $vmlinux;

open FD, ">$keyring" || die $keyring;

binmode(FD);

$len = syswrite(FD, $buf, $size);

die "$keyring" if (!defined($len));

die "Short write on $keyring\n" if ($len != $size);

close(FD) || die $keyring;