From 2221a6ee73e7c8f43af802a1ef9426d4b0d122d3 Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 21 Oct 2015 14:04:47 +0100 Subject: [PATCH] KEYS: Provide a script to extract the sys cert list from a vmlinux file The supplied script takes a vmlinux file - and if necessary a System.map file - locates the system certificates list and extracts it to the named file. Call as: ./scripts/extract-sys-certs vmlinux certs if vmlinux contains symbols and: ./scripts/extract-sys-certs -s System.map vmlinux certs if it does not. It prints something like the following to stdout: Have 27 sections No symbols in vmlinux, trying System.map Have 80088 symbols Have 1346 bytes of certs at VMA 0xffffffff8201c540 Certificate list in section .init.data Certificate list at file offset 0x141c540 If vmlinux contains symbols then that is used rather than System.map - even if one is given. Signed-off-by: David Howells --- scripts/extract-sys-certs.pl | 144 +++++++++++++++++++++++++++++++++++ 1 file changed, 144 insertions(+) create mode 100755 scripts/extract-sys-certs.pl diff --git a/scripts/extract-sys-certs.pl b/scripts/extract-sys-certs.pl new file mode 100755 index 000000000000..d476e7d1fd88 --- /dev/null +++ b/scripts/extract-sys-certs.pl @@ -0,0 +1,144 @@ +#!/usr/bin/perl -w +# +use strict; +use Math::BigInt; +use Fcntl "SEEK_SET"; + +die "Format: $0 [-s ] \n" + if ($#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 = ; +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 = ; +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 = ; + 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; -- 2.20.1