Viewing file:  extract-sys-certs.pl (3.75 KB) -rwxr-xr-x
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#!/usr/bin/env perl
# SPDX-License-Identifier: GPL-2.0
#
use warnings;
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{"system_certificate_list_size"}));
my $start = Math::BigInt->new($symbols{"__cert_list_start"});
my $end;
my $size;
my $size_sym = Math::BigInt->new($symbols{"system_certificate_list_size"});
open FD, "<$vmlinux" || die $vmlinux;
binmode(FD);
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 >= $s_vend);
die "Certificate list size was not found on the same section\n"
if ($size_sym < $s_vma || $size_sym > $s_vend);
die "Cert object in multiple sections: ", $s_name, " and ", $s->{name}, "\n"
if ($s);
my $size_off = $size_sym -$s_vma + $s_foff;
my $packed;
die $vmlinux if (!defined(sysseek(FD, $size_off, SEEK_SET)));
sysread(FD, $packed, 8);
$size = unpack 'L!', $packed;
$end = $start + $size;
printf "Have %u bytes of certs at VMA 0x%x\n", $size, $start;
die "Cert object partially overflows section $s_name\n"
if ($end > $s_vend);
$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;
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;
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