diff options
| -rwxr-xr-x | scripts/extract-module-sig.pl | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/scripts/extract-module-sig.pl b/scripts/extract-module-sig.pl new file mode 100755 index 000000000000..faac6f2e377f --- /dev/null +++ b/scripts/extract-module-sig.pl @@ -0,0 +1,136 @@ +#!/usr/bin/perl -w +# +# extract-mod-sig <part> <module-file> +# +# Reads the module file and writes out some or all of the signature +# section to stdout. Part is the bit to be written and is one of: +# +# -0: The unsigned module, no signature data at all +# -a: All of the signature data, including magic number +# -d: Just the descriptor values as a sequence of numbers +# -n: Just the signer's name +# -k: Just the key ID +# -s: Just the crypto signature or PKCS#7 message +# +use strict; + +die "Format: $0 -[0adnks] module-file >out\n" + if ($#ARGV != 1); + +my $part = $ARGV[0]; +my $modfile = $ARGV[1]; + +my $magic_number = "~Module signature appended~\n"; + +# +# Read the module contents +# +open FD, "<$modfile" || die $modfile; +binmode(FD); +my @st = stat(FD); +die "$modfile" unless (@st); +my $buf = ""; +my $len = sysread(FD, $buf, $st[7]); +die "$modfile" unless (defined($len)); +die "Short read on $modfile\n" unless ($len == $st[7]); +close(FD) || die $modfile; + +print STDERR "Read ", $len, " bytes from module file\n"; + +die "The file is too short to have a sig magic number and descriptor\n" + if ($len < 12 + length($magic_number)); + +# +# Check for the magic number and extract the information block +# +my $p = $len - length($magic_number); +my $raw_magic = substr($buf, $p); + +die "Magic number not found at $len\n" + if ($raw_magic ne $magic_number); +print STDERR "Found magic number at $len\n"; + +$p -= 12; +my $raw_info = substr($buf, $p, 12); + +my @info = unpack("CCCCCxxxN", $raw_info); +my ($algo, $hash, $id_type, $name_len, $kid_len, $sig_len) = @info; + +if ($id_type == 0) { + print STDERR "Found PGP key identifier\n"; +} elsif ($id_type == 1) { + print STDERR "Found X.509 cert identifier\n"; +} elsif ($id_type == 2) { + print STDERR "Found PKCS#7/CMS encapsulation\n"; +} else { + print STDERR "Found unsupported identifier type $id_type\n"; +} + +# +# Extract the three pieces of info data +# +die "Insufficient name+kid+sig data in file\n" + unless ($p >= $name_len + $kid_len + $sig_len); + +$p -= $sig_len; +my $raw_sig = substr($buf, $p, $sig_len); +$p -= $kid_len; +my $raw_kid = substr($buf, $p, $kid_len); +$p -= $name_len; +my $raw_name = substr($buf, $p, $name_len); + +my $module_len = $p; + +if ($sig_len > 0) { + print STDERR "Found $sig_len bytes of signature ["; + my $n = $sig_len > 16 ? 16 : $sig_len; + foreach my $i (unpack("C" x $n, substr($raw_sig, 0, $n))) { + printf STDERR "%02x", $i; + } + print STDERR "]\n"; +} + +if ($kid_len > 0) { + print STDERR "Found $kid_len bytes of key identifier ["; + my $n = $kid_len > 16 ? 16 : $kid_len; + foreach my $i (unpack("C" x $n, substr($raw_kid, 0, $n))) { + printf STDERR "%02x", $i; + } + print STDERR "]\n"; +} + +if ($name_len > 0) { + print STDERR "Found $name_len bytes of signer's name [$raw_name]\n"; +} + +# +# Produce the requested output +# +if ($part eq "-0") { + # The unsigned module, no signature data at all + binmode(STDOUT); + print substr($buf, 0, $module_len); +} elsif ($part eq "-a") { + # All of the signature data, including magic number + binmode(STDOUT); + print substr($buf, $module_len); +} elsif ($part eq "-d") { + # Just the descriptor values as a sequence of numbers + print join(" ", @info), "\n"; +} elsif ($part eq "-n") { + # Just the signer's name + print STDERR "No signer's name for PKCS#7 message type sig\n" + if ($id_type == 2); + binmode(STDOUT); + print $raw_name; +} elsif ($part eq "-k") { + # Just the key identifier + print STDERR "No key ID for PKCS#7 message type sig\n" + if ($id_type == 2); + binmode(STDOUT); + print $raw_kid; +} elsif ($part eq "-s") { + # Just the crypto signature or PKCS#7 message + binmode(STDOUT); + print $raw_sig; +} |