576 lines
15 KiB
Perl
576 lines
15 KiB
Perl
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package Opcode;
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require 5.002;
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use vars qw($VERSION $XS_VERSION @ISA @EXPORT_OK);
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$VERSION = "1.04";
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$XS_VERSION = "1.03";
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use strict;
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use Carp;
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use Exporter ();
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use DynaLoader ();
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@ISA = qw(Exporter DynaLoader);
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BEGIN {
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@EXPORT_OK = qw(
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opset ops_to_opset
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opset_to_ops opset_to_hex invert_opset
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empty_opset full_opset
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opdesc opcodes opmask define_optag
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opmask_add verify_opset opdump
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);
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}
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sub opset (;@);
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sub opset_to_hex ($);
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sub opdump (;$);
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use subs @EXPORT_OK;
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bootstrap Opcode $XS_VERSION;
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_init_optags();
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sub ops_to_opset { opset @_ } # alias for old name
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sub opset_to_hex ($) {
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return "(invalid opset)" unless verify_opset($_[0]);
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unpack("h*",$_[0]);
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}
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sub opdump (;$) {
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my $pat = shift;
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# handy utility: perl -MOpcode=opdump -e 'opdump File'
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foreach(opset_to_ops(full_opset)) {
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my $op = sprintf " %12s %s\n", $_, opdesc($_);
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next if defined $pat and $op !~ m/$pat/i;
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print $op;
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}
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}
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sub _init_optags {
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my(%all, %seen);
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@all{opset_to_ops(full_opset)} = (); # keys only
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local($_);
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local($/) = "\n=cut"; # skip to optags definition section
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<DATA>;
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$/ = "\n="; # now read in 'pod section' chunks
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while(<DATA>) {
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next unless m/^item\s+(:\w+)/;
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my $tag = $1;
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# Split into lines, keep only indented lines
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my @lines = grep { m/^\s/ } split(/\n/);
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foreach (@lines) { s/--.*// } # delete comments
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my @ops = map { split ' ' } @lines; # get op words
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foreach(@ops) {
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warn "$tag - $_ already tagged in $seen{$_}\n" if $seen{$_};
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$seen{$_} = $tag;
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delete $all{$_};
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}
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# opset will croak on invalid names
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define_optag($tag, opset(@ops));
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}
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close(DATA);
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warn "Untagged opnames: ".join(' ',keys %all)."\n" if %all;
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}
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1;
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__DATA__
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=head1 NAME
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Opcode - Disable named opcodes when compiling perl code
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=head1 SYNOPSIS
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use Opcode;
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=head1 DESCRIPTION
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Perl code is always compiled into an internal format before execution.
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Evaluating perl code (e.g. via "eval" or "do 'file'") causes
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the code to be compiled into an internal format and then,
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provided there was no error in the compilation, executed.
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The internal format is based on many distinct I<opcodes>.
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By default no opmask is in effect and any code can be compiled.
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The Opcode module allow you to define an I<operator mask> to be in
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effect when perl I<next> compiles any code. Attempting to compile code
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which contains a masked opcode will cause the compilation to fail
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with an error. The code will not be executed.
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=head1 NOTE
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The Opcode module is not usually used directly. See the ops pragma and
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Safe modules for more typical uses.
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=head1 WARNING
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The authors make B<no warranty>, implied or otherwise, about the
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suitability of this software for safety or security purposes.
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The authors shall not in any case be liable for special, incidental,
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consequential, indirect or other similar damages arising from the use
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of this software.
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Your mileage will vary. If in any doubt B<do not use it>.
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=head1 Operator Names and Operator Lists
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The canonical list of operator names is the contents of the array
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op_name defined and initialised in file F<opcode.h> of the Perl
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source distribution (and installed into the perl library).
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Each operator has both a terse name (its opname) and a more verbose or
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recognisable descriptive name. The opdesc function can be used to
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return a list of descriptions for a list of operators.
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Many of the functions and methods listed below take a list of
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operators as parameters. Most operator lists can be made up of several
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types of element. Each element can be one of
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=over 8
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=item an operator name (opname)
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Operator names are typically small lowercase words like enterloop,
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leaveloop, last, next, redo etc. Sometimes they are rather cryptic
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like gv2cv, i_ncmp and ftsvtx.
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=item an operator tag name (optag)
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Operator tags can be used to refer to groups (or sets) of operators.
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Tag names always begin with a colon. The Opcode module defines several
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optags and the user can define others using the define_optag function.
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=item a negated opname or optag
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An opname or optag can be prefixed with an exclamation mark, e.g., !mkdir.
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Negating an opname or optag means remove the corresponding ops from the
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accumulated set of ops at that point.
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=item an operator set (opset)
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An I<opset> as a binary string of approximately 43 bytes which holds a
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set or zero or more operators.
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The opset and opset_to_ops functions can be used to convert from
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a list of operators to an opset and I<vice versa>.
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Wherever a list of operators can be given you can use one or more opsets.
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See also Manipulating Opsets below.
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=back
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=head1 Opcode Functions
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The Opcode package contains functions for manipulating operator names
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tags and sets. All are available for export by the package.
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=over 8
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=item opcodes
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In a scalar context opcodes returns the number of opcodes in this
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version of perl (around 340 for perl5.002).
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In a list context it returns a list of all the operator names.
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(Not yet implemented, use @names = opset_to_ops(full_opset).)
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=item opset (OP, ...)
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Returns an opset containing the listed operators.
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=item opset_to_ops (OPSET)
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Returns a list of operator names corresponding to those operators in
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the set.
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=item opset_to_hex (OPSET)
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Returns a string representation of an opset. Can be handy for debugging.
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=item full_opset
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Returns an opset which includes all operators.
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=item empty_opset
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Returns an opset which contains no operators.
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=item invert_opset (OPSET)
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Returns an opset which is the inverse set of the one supplied.
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=item verify_opset (OPSET, ...)
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Returns true if the supplied opset looks like a valid opset (is the
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right length etc) otherwise it returns false. If an optional second
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parameter is true then verify_opset will croak on an invalid opset
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instead of returning false.
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Most of the other Opcode functions call verify_opset automatically
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and will croak if given an invalid opset.
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=item define_optag (OPTAG, OPSET)
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Define OPTAG as a symbolic name for OPSET. Optag names always start
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with a colon C<:>.
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The optag name used must not be defined already (define_optag will
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croak if it is already defined). Optag names are global to the perl
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process and optag definitions cannot be altered or deleted once
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defined.
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It is strongly recommended that applications using Opcode should use a
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leading capital letter on their tag names since lowercase names are
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reserved for use by the Opcode module. If using Opcode within a module
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you should prefix your tags names with the name of your module to
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ensure uniqueness and thus avoid clashes with other modules.
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=item opmask_add (OPSET)
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Adds the supplied opset to the current opmask. Note that there is
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currently I<no> mechanism for unmasking ops once they have been masked.
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This is intentional.
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=item opmask
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Returns an opset corresponding to the current opmask.
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=item opdesc (OP, ...)
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This takes a list of operator names and returns the corresponding list
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of operator descriptions.
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=item opdump (PAT)
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Dumps to STDOUT a two column list of op names and op descriptions.
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If an optional pattern is given then only lines which match the
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(case insensitive) pattern will be output.
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It's designed to be used as a handy command line utility:
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perl -MOpcode=opdump -e opdump
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perl -MOpcode=opdump -e 'opdump Eval'
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=back
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=head1 Manipulating Opsets
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Opsets may be manipulated using the perl bit vector operators & (and), | (or),
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^ (xor) and ~ (negate/invert).
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However you should never rely on the numerical position of any opcode
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within the opset. In other words both sides of a bit vector operator
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should be opsets returned from Opcode functions.
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Also, since the number of opcodes in your current version of perl might
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not be an exact multiple of eight, there may be unused bits in the last
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byte of an upset. This should not cause any problems (Opcode functions
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ignore those extra bits) but it does mean that using the ~ operator
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will typically not produce the same 'physical' opset 'string' as the
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invert_opset function.
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=head1 TO DO (maybe)
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$bool = opset_eq($opset1, $opset2) true if opsets are logically eqiv
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$yes = opset_can($opset, @ops) true if $opset has all @ops set
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@diff = opset_diff($opset1, $opset2) => ('foo', '!bar', ...)
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=cut
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# the =cut above is used by _init_optags() to get here quickly
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=head1 Predefined Opcode Tags
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=over 5
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=item :base_core
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null stub scalar pushmark wantarray const defined undef
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rv2sv sassign
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rv2av aassign aelem aelemfast aslice av2arylen
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rv2hv helem hslice each values keys exists delete
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preinc i_preinc predec i_predec postinc i_postinc postdec i_postdec
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int hex oct abs pow multiply i_multiply divide i_divide
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modulo i_modulo add i_add subtract i_subtract
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left_shift right_shift bit_and bit_xor bit_or negate i_negate
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not complement
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lt i_lt gt i_gt le i_le ge i_ge eq i_eq ne i_ne ncmp i_ncmp
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slt sgt sle sge seq sne scmp
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substr vec stringify study pos length index rindex ord chr
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ucfirst lcfirst uc lc quotemeta trans chop schop chomp schomp
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match split qr
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list lslice splice push pop shift unshift reverse
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cond_expr flip flop andassign orassign and or xor
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warn die lineseq nextstate unstack scope enter leave
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rv2cv anoncode prototype
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entersub leavesub return method -- XXX loops via recursion?
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leaveeval -- needed for Safe to operate, is safe without entereval
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=item :base_mem
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These memory related ops are not included in :base_core because they
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can easily be used to implement a resource attack (e.g., consume all
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available memory).
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concat repeat join range
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anonlist anonhash
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Note that despite the existance of this optag a memory resource attack
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may still be possible using only :base_core ops.
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Disabling these ops is a I<very> heavy handed way to attempt to prevent
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a memory resource attack. It's probable that a specific memory limit
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mechanism will be added to perl in the near future.
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=item :base_loop
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These loop ops are not included in :base_core because they can easily be
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used to implement a resource attack (e.g., consume all available CPU time).
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grepstart grepwhile
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mapstart mapwhile
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enteriter iter
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enterloop leaveloop
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last next redo
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goto
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=item :base_io
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These ops enable I<filehandle> (rather than filename) based input and
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output. These are safe on the assumption that only pre-existing
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filehandles are available for use. To create new filehandles other ops
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such as open would need to be enabled.
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readline rcatline getc read
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formline enterwrite leavewrite
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print sysread syswrite send recv
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eof tell seek sysseek
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readdir telldir seekdir rewinddir
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=item :base_orig
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These are a hotchpotch of opcodes still waiting to be considered
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gvsv gv gelem
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padsv padav padhv padany
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rv2gv refgen srefgen ref
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bless -- could be used to change ownership of objects (reblessing)
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pushre regcmaybe regcreset regcomp subst substcont
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sprintf prtf -- can core dump
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|
crypt
|
||
|
|
|
||
|
|
tie untie
|
||
|
|
|
||
|
|
dbmopen dbmclose
|
||
|
|
sselect select
|
||
|
|
pipe_op sockpair
|
||
|
|
|
||
|
|
getppid getpgrp setpgrp getpriority setpriority localtime gmtime
|
||
|
|
|
||
|
|
entertry leavetry -- can be used to 'hide' fatal errors
|
||
|
|
|
||
|
|
=item :base_math
|
||
|
|
|
||
|
|
These ops are not included in :base_core because of the risk of them being
|
||
|
|
used to generate floating point exceptions (which would have to be caught
|
||
|
|
using a $SIG{FPE} handler).
|
||
|
|
|
||
|
|
atan2 sin cos exp log sqrt
|
||
|
|
|
||
|
|
These ops are not included in :base_core because they have an effect
|
||
|
|
beyond the scope of the compartment.
|
||
|
|
|
||
|
|
rand srand
|
||
|
|
|
||
|
|
=item :base_thread
|
||
|
|
|
||
|
|
These ops are related to multi-threading.
|
||
|
|
|
||
|
|
lock threadsv
|
||
|
|
|
||
|
|
=item :default
|
||
|
|
|
||
|
|
A handy tag name for a I<reasonable> default set of ops. (The current ops
|
||
|
|
allowed are unstable while development continues. It will change.)
|
||
|
|
|
||
|
|
:base_core :base_mem :base_loop :base_io :base_orig :base_thread
|
||
|
|
|
||
|
|
If safety matters to you (and why else would you be using the Opcode module?)
|
||
|
|
then you should not rely on the definition of this, or indeed any other, optag!
|
||
|
|
|
||
|
|
|
||
|
|
=item :filesys_read
|
||
|
|
|
||
|
|
stat lstat readlink
|
||
|
|
|
||
|
|
ftatime ftblk ftchr ftctime ftdir fteexec fteowned fteread
|
||
|
|
ftewrite ftfile ftis ftlink ftmtime ftpipe ftrexec ftrowned
|
||
|
|
ftrread ftsgid ftsize ftsock ftsuid fttty ftzero ftrwrite ftsvtx
|
||
|
|
|
||
|
|
fttext ftbinary
|
||
|
|
|
||
|
|
fileno
|
||
|
|
|
||
|
|
=item :sys_db
|
||
|
|
|
||
|
|
ghbyname ghbyaddr ghostent shostent ehostent -- hosts
|
||
|
|
gnbyname gnbyaddr gnetent snetent enetent -- networks
|
||
|
|
gpbyname gpbynumber gprotoent sprotoent eprotoent -- protocols
|
||
|
|
gsbyname gsbyport gservent sservent eservent -- services
|
||
|
|
|
||
|
|
gpwnam gpwuid gpwent spwent epwent getlogin -- users
|
||
|
|
ggrnam ggrgid ggrent sgrent egrent -- groups
|
||
|
|
|
||
|
|
=item :browse
|
||
|
|
|
||
|
|
A handy tag name for a I<reasonable> default set of ops beyond the
|
||
|
|
:default optag. Like :default (and indeed all the other optags) its
|
||
|
|
current definition is unstable while development continues. It will change.
|
||
|
|
|
||
|
|
The :browse tag represents the next step beyond :default. It it a
|
||
|
|
superset of the :default ops and adds :filesys_read the :sys_db.
|
||
|
|
The intent being that scripts can access more (possibly sensitive)
|
||
|
|
information about your system but not be able to change it.
|
||
|
|
|
||
|
|
:default :filesys_read :sys_db
|
||
|
|
|
||
|
|
=item :filesys_open
|
||
|
|
|
||
|
|
sysopen open close
|
||
|
|
umask binmode
|
||
|
|
|
||
|
|
open_dir closedir -- other dir ops are in :base_io
|
||
|
|
|
||
|
|
=item :filesys_write
|
||
|
|
|
||
|
|
link unlink rename symlink truncate
|
||
|
|
|
||
|
|
mkdir rmdir
|
||
|
|
|
||
|
|
utime chmod chown
|
||
|
|
|
||
|
|
fcntl -- not strictly filesys related, but possibly as dangerous?
|
||
|
|
|
||
|
|
=item :subprocess
|
||
|
|
|
||
|
|
backtick system
|
||
|
|
|
||
|
|
fork
|
||
|
|
|
||
|
|
wait waitpid
|
||
|
|
|
||
|
|
glob -- access to Cshell via <`rm *`>
|
||
|
|
|
||
|
|
=item :ownprocess
|
||
|
|
|
||
|
|
exec exit kill
|
||
|
|
|
||
|
|
time tms -- could be used for timing attacks (paranoid?)
|
||
|
|
|
||
|
|
=item :others
|
||
|
|
|
||
|
|
This tag holds groups of assorted specialist opcodes that don't warrant
|
||
|
|
having optags defined for them.
|
||
|
|
|
||
|
|
SystemV Interprocess Communications:
|
||
|
|
|
||
|
|
msgctl msgget msgrcv msgsnd
|
||
|
|
|
||
|
|
semctl semget semop
|
||
|
|
|
||
|
|
shmctl shmget shmread shmwrite
|
||
|
|
|
||
|
|
=item :still_to_be_decided
|
||
|
|
|
||
|
|
chdir
|
||
|
|
flock ioctl
|
||
|
|
|
||
|
|
socket getpeername ssockopt
|
||
|
|
bind connect listen accept shutdown gsockopt getsockname
|
||
|
|
|
||
|
|
sleep alarm -- changes global timer state and signal handling
|
||
|
|
sort -- assorted problems including core dumps
|
||
|
|
tied -- can be used to access object implementing a tie
|
||
|
|
pack unpack -- can be used to create/use memory pointers
|
||
|
|
|
||
|
|
entereval -- can be used to hide code from initial compile
|
||
|
|
require dofile
|
||
|
|
|
||
|
|
caller -- get info about calling environment and args
|
||
|
|
|
||
|
|
reset
|
||
|
|
|
||
|
|
dbstate -- perl -d version of nextstate(ment) opcode
|
||
|
|
|
||
|
|
=item :dangerous
|
||
|
|
|
||
|
|
This tag is simply a bucket for opcodes that are unlikely to be used via
|
||
|
|
a tag name but need to be tagged for completness and documentation.
|
||
|
|
|
||
|
|
syscall dump chroot
|
||
|
|
|
||
|
|
|
||
|
|
=back
|
||
|
|
|
||
|
|
=head1 SEE ALSO
|
||
|
|
|
||
|
|
ops(3) -- perl pragma interface to Opcode module.
|
||
|
|
|
||
|
|
Safe(3) -- Opcode and namespace limited execution compartments
|
||
|
|
|
||
|
|
=head1 AUTHORS
|
||
|
|
|
||
|
|
Originally designed and implemented by Malcolm Beattie,
|
||
|
|
mbeattie@sable.ox.ac.uk as part of Safe version 1.
|
||
|
|
|
||
|
|
Split out from Safe module version 1, named opcode tags and other
|
||
|
|
changes added by Tim Bunce.
|
||
|
|
|
||
|
|
=cut
|
||
|
|
|