| 1 | package Opcode; |
| 2 | |
| 3 | use 5.006_001; |
| 4 | |
| 5 | use strict; |
| 6 | |
| 7 | our($VERSION, $XS_VERSION, @ISA, @EXPORT_OK); |
| 8 | |
| 9 | $VERSION = "1.06"; |
| 10 | $XS_VERSION = "1.03"; |
| 11 | |
| 12 | use Carp; |
| 13 | use Exporter (); |
| 14 | use XSLoader (); |
| 15 | |
| 16 | BEGIN { |
| 17 | @ISA = qw(Exporter); |
| 18 | @EXPORT_OK = qw( |
| 19 | opset ops_to_opset |
| 20 | opset_to_ops opset_to_hex invert_opset |
| 21 | empty_opset full_opset |
| 22 | opdesc opcodes opmask define_optag |
| 23 | opmask_add verify_opset opdump |
| 24 | ); |
| 25 | } |
| 26 | |
| 27 | sub opset (;@); |
| 28 | sub opset_to_hex ($); |
| 29 | sub opdump (;$); |
| 30 | use subs @EXPORT_OK; |
| 31 | |
| 32 | XSLoader::load 'Opcode', $XS_VERSION; |
| 33 | |
| 34 | _init_optags(); |
| 35 | |
| 36 | sub ops_to_opset { opset @_ } # alias for old name |
| 37 | |
| 38 | sub opset_to_hex ($) { |
| 39 | return "(invalid opset)" unless verify_opset($_[0]); |
| 40 | unpack("h*",$_[0]); |
| 41 | } |
| 42 | |
| 43 | sub opdump (;$) { |
| 44 | my $pat = shift; |
| 45 | # handy utility: perl -MOpcode=opdump -e 'opdump File' |
| 46 | foreach(opset_to_ops(full_opset)) { |
| 47 | my $op = sprintf " %12s %s\n", $_, opdesc($_); |
| 48 | next if defined $pat and $op !~ m/$pat/i; |
| 49 | print $op; |
| 50 | } |
| 51 | } |
| 52 | |
| 53 | |
| 54 | |
| 55 | sub _init_optags { |
| 56 | my(%all, %seen); |
| 57 | @all{opset_to_ops(full_opset)} = (); # keys only |
| 58 | |
| 59 | local($_); |
| 60 | local($/) = "\n=cut"; # skip to optags definition section |
| 61 | <DATA>; |
| 62 | $/ = "\n="; # now read in 'pod section' chunks |
| 63 | while(<DATA>) { |
| 64 | next unless m/^item\s+(:\w+)/; |
| 65 | my $tag = $1; |
| 66 | |
| 67 | # Split into lines, keep only indented lines |
| 68 | my @lines = grep { m/^\s/ } split(/\n/); |
| 69 | foreach (@lines) { s/--.*// } # delete comments |
| 70 | my @ops = map { split ' ' } @lines; # get op words |
| 71 | |
| 72 | foreach(@ops) { |
| 73 | warn "$tag - $_ already tagged in $seen{$_}\n" if $seen{$_}; |
| 74 | $seen{$_} = $tag; |
| 75 | delete $all{$_}; |
| 76 | } |
| 77 | # opset will croak on invalid names |
| 78 | define_optag($tag, opset(@ops)); |
| 79 | } |
| 80 | close(DATA); |
| 81 | warn "Untagged opnames: ".join(' ',keys %all)."\n" if %all; |
| 82 | } |
| 83 | |
| 84 | |
| 85 | 1; |
| 86 | |
| 87 | __DATA__ |
| 88 | |
| 89 | =head1 NAME |
| 90 | |
| 91 | Opcode - Disable named opcodes when compiling perl code |
| 92 | |
| 93 | =head1 SYNOPSIS |
| 94 | |
| 95 | use Opcode; |
| 96 | |
| 97 | |
| 98 | =head1 DESCRIPTION |
| 99 | |
| 100 | Perl code is always compiled into an internal format before execution. |
| 101 | |
| 102 | Evaluating perl code (e.g. via "eval" or "do 'file'") causes |
| 103 | the code to be compiled into an internal format and then, |
| 104 | provided there was no error in the compilation, executed. |
| 105 | The internal format is based on many distinct I<opcodes>. |
| 106 | |
| 107 | By default no opmask is in effect and any code can be compiled. |
| 108 | |
| 109 | The Opcode module allow you to define an I<operator mask> to be in |
| 110 | effect when perl I<next> compiles any code. Attempting to compile code |
| 111 | which contains a masked opcode will cause the compilation to fail |
| 112 | with an error. The code will not be executed. |
| 113 | |
| 114 | =head1 NOTE |
| 115 | |
| 116 | The Opcode module is not usually used directly. See the ops pragma and |
| 117 | Safe modules for more typical uses. |
| 118 | |
| 119 | =head1 WARNING |
| 120 | |
| 121 | The authors make B<no warranty>, implied or otherwise, about the |
| 122 | suitability of this software for safety or security purposes. |
| 123 | |
| 124 | The authors shall not in any case be liable for special, incidental, |
| 125 | consequential, indirect or other similar damages arising from the use |
| 126 | of this software. |
| 127 | |
| 128 | Your mileage will vary. If in any doubt B<do not use it>. |
| 129 | |
| 130 | |
| 131 | =head1 Operator Names and Operator Lists |
| 132 | |
| 133 | The canonical list of operator names is the contents of the array |
| 134 | PL_op_name defined and initialised in file F<opcode.h> of the Perl |
| 135 | source distribution (and installed into the perl library). |
| 136 | |
| 137 | Each operator has both a terse name (its opname) and a more verbose or |
| 138 | recognisable descriptive name. The opdesc function can be used to |
| 139 | return a list of descriptions for a list of operators. |
| 140 | |
| 141 | Many of the functions and methods listed below take a list of |
| 142 | operators as parameters. Most operator lists can be made up of several |
| 143 | types of element. Each element can be one of |
| 144 | |
| 145 | =over 8 |
| 146 | |
| 147 | =item an operator name (opname) |
| 148 | |
| 149 | Operator names are typically small lowercase words like enterloop, |
| 150 | leaveloop, last, next, redo etc. Sometimes they are rather cryptic |
| 151 | like gv2cv, i_ncmp and ftsvtx. |
| 152 | |
| 153 | =item an operator tag name (optag) |
| 154 | |
| 155 | Operator tags can be used to refer to groups (or sets) of operators. |
| 156 | Tag names always begin with a colon. The Opcode module defines several |
| 157 | optags and the user can define others using the define_optag function. |
| 158 | |
| 159 | =item a negated opname or optag |
| 160 | |
| 161 | An opname or optag can be prefixed with an exclamation mark, e.g., !mkdir. |
| 162 | Negating an opname or optag means remove the corresponding ops from the |
| 163 | accumulated set of ops at that point. |
| 164 | |
| 165 | =item an operator set (opset) |
| 166 | |
| 167 | An I<opset> as a binary string of approximately 44 bytes which holds a |
| 168 | set or zero or more operators. |
| 169 | |
| 170 | The opset and opset_to_ops functions can be used to convert from |
| 171 | a list of operators to an opset and I<vice versa>. |
| 172 | |
| 173 | Wherever a list of operators can be given you can use one or more opsets. |
| 174 | See also Manipulating Opsets below. |
| 175 | |
| 176 | =back |
| 177 | |
| 178 | |
| 179 | =head1 Opcode Functions |
| 180 | |
| 181 | The Opcode package contains functions for manipulating operator names |
| 182 | tags and sets. All are available for export by the package. |
| 183 | |
| 184 | =over 8 |
| 185 | |
| 186 | =item opcodes |
| 187 | |
| 188 | In a scalar context opcodes returns the number of opcodes in this |
| 189 | version of perl (around 350 for perl-5.7.0). |
| 190 | |
| 191 | In a list context it returns a list of all the operator names. |
| 192 | (Not yet implemented, use @names = opset_to_ops(full_opset).) |
| 193 | |
| 194 | =item opset (OP, ...) |
| 195 | |
| 196 | Returns an opset containing the listed operators. |
| 197 | |
| 198 | =item opset_to_ops (OPSET) |
| 199 | |
| 200 | Returns a list of operator names corresponding to those operators in |
| 201 | the set. |
| 202 | |
| 203 | =item opset_to_hex (OPSET) |
| 204 | |
| 205 | Returns a string representation of an opset. Can be handy for debugging. |
| 206 | |
| 207 | =item full_opset |
| 208 | |
| 209 | Returns an opset which includes all operators. |
| 210 | |
| 211 | =item empty_opset |
| 212 | |
| 213 | Returns an opset which contains no operators. |
| 214 | |
| 215 | =item invert_opset (OPSET) |
| 216 | |
| 217 | Returns an opset which is the inverse set of the one supplied. |
| 218 | |
| 219 | =item verify_opset (OPSET, ...) |
| 220 | |
| 221 | Returns true if the supplied opset looks like a valid opset (is the |
| 222 | right length etc) otherwise it returns false. If an optional second |
| 223 | parameter is true then verify_opset will croak on an invalid opset |
| 224 | instead of returning false. |
| 225 | |
| 226 | Most of the other Opcode functions call verify_opset automatically |
| 227 | and will croak if given an invalid opset. |
| 228 | |
| 229 | =item define_optag (OPTAG, OPSET) |
| 230 | |
| 231 | Define OPTAG as a symbolic name for OPSET. Optag names always start |
| 232 | with a colon C<:>. |
| 233 | |
| 234 | The optag name used must not be defined already (define_optag will |
| 235 | croak if it is already defined). Optag names are global to the perl |
| 236 | process and optag definitions cannot be altered or deleted once |
| 237 | defined. |
| 238 | |
| 239 | It is strongly recommended that applications using Opcode should use a |
| 240 | leading capital letter on their tag names since lowercase names are |
| 241 | reserved for use by the Opcode module. If using Opcode within a module |
| 242 | you should prefix your tags names with the name of your module to |
| 243 | ensure uniqueness and thus avoid clashes with other modules. |
| 244 | |
| 245 | =item opmask_add (OPSET) |
| 246 | |
| 247 | Adds the supplied opset to the current opmask. Note that there is |
| 248 | currently I<no> mechanism for unmasking ops once they have been masked. |
| 249 | This is intentional. |
| 250 | |
| 251 | =item opmask |
| 252 | |
| 253 | Returns an opset corresponding to the current opmask. |
| 254 | |
| 255 | =item opdesc (OP, ...) |
| 256 | |
| 257 | This takes a list of operator names and returns the corresponding list |
| 258 | of operator descriptions. |
| 259 | |
| 260 | =item opdump (PAT) |
| 261 | |
| 262 | Dumps to STDOUT a two column list of op names and op descriptions. |
| 263 | If an optional pattern is given then only lines which match the |
| 264 | (case insensitive) pattern will be output. |
| 265 | |
| 266 | It's designed to be used as a handy command line utility: |
| 267 | |
| 268 | perl -MOpcode=opdump -e opdump |
| 269 | perl -MOpcode=opdump -e 'opdump Eval' |
| 270 | |
| 271 | =back |
| 272 | |
| 273 | =head1 Manipulating Opsets |
| 274 | |
| 275 | Opsets may be manipulated using the perl bit vector operators & (and), | (or), |
| 276 | ^ (xor) and ~ (negate/invert). |
| 277 | |
| 278 | However you should never rely on the numerical position of any opcode |
| 279 | within the opset. In other words both sides of a bit vector operator |
| 280 | should be opsets returned from Opcode functions. |
| 281 | |
| 282 | Also, since the number of opcodes in your current version of perl might |
| 283 | not be an exact multiple of eight, there may be unused bits in the last |
| 284 | byte of an upset. This should not cause any problems (Opcode functions |
| 285 | ignore those extra bits) but it does mean that using the ~ operator |
| 286 | will typically not produce the same 'physical' opset 'string' as the |
| 287 | invert_opset function. |
| 288 | |
| 289 | |
| 290 | =head1 TO DO (maybe) |
| 291 | |
| 292 | $bool = opset_eq($opset1, $opset2) true if opsets are logically eqiv |
| 293 | |
| 294 | $yes = opset_can($opset, @ops) true if $opset has all @ops set |
| 295 | |
| 296 | @diff = opset_diff($opset1, $opset2) => ('foo', '!bar', ...) |
| 297 | |
| 298 | =cut |
| 299 | |
| 300 | # the =cut above is used by _init_optags() to get here quickly |
| 301 | |
| 302 | =head1 Predefined Opcode Tags |
| 303 | |
| 304 | =over 5 |
| 305 | |
| 306 | =item :base_core |
| 307 | |
| 308 | null stub scalar pushmark wantarray const defined undef |
| 309 | |
| 310 | rv2sv sassign |
| 311 | |
| 312 | rv2av aassign aelem aelemfast aslice av2arylen |
| 313 | |
| 314 | rv2hv helem hslice each values keys exists delete |
| 315 | |
| 316 | preinc i_preinc predec i_predec postinc i_postinc postdec i_postdec |
| 317 | int hex oct abs pow multiply i_multiply divide i_divide |
| 318 | modulo i_modulo add i_add subtract i_subtract |
| 319 | |
| 320 | left_shift right_shift bit_and bit_xor bit_or negate i_negate |
| 321 | not complement |
| 322 | |
| 323 | lt i_lt gt i_gt le i_le ge i_ge eq i_eq ne i_ne ncmp i_ncmp |
| 324 | slt sgt sle sge seq sne scmp |
| 325 | |
| 326 | substr vec stringify study pos length index rindex ord chr |
| 327 | |
| 328 | ucfirst lcfirst uc lc quotemeta trans chop schop chomp schomp |
| 329 | |
| 330 | match split qr |
| 331 | |
| 332 | list lslice splice push pop shift unshift reverse |
| 333 | |
| 334 | cond_expr flip flop andassign orassign and or xor |
| 335 | |
| 336 | warn die lineseq nextstate scope enter leave setstate |
| 337 | |
| 338 | rv2cv anoncode prototype |
| 339 | |
| 340 | entersub leavesub leavesublv return method method_named -- XXX loops via recursion? |
| 341 | |
| 342 | leaveeval -- needed for Safe to operate, is safe without entereval |
| 343 | |
| 344 | =item :base_mem |
| 345 | |
| 346 | These memory related ops are not included in :base_core because they |
| 347 | can easily be used to implement a resource attack (e.g., consume all |
| 348 | available memory). |
| 349 | |
| 350 | concat repeat join range |
| 351 | |
| 352 | anonlist anonhash |
| 353 | |
| 354 | Note that despite the existence of this optag a memory resource attack |
| 355 | may still be possible using only :base_core ops. |
| 356 | |
| 357 | Disabling these ops is a I<very> heavy handed way to attempt to prevent |
| 358 | a memory resource attack. It's probable that a specific memory limit |
| 359 | mechanism will be added to perl in the near future. |
| 360 | |
| 361 | =item :base_loop |
| 362 | |
| 363 | These loop ops are not included in :base_core because they can easily be |
| 364 | used to implement a resource attack (e.g., consume all available CPU time). |
| 365 | |
| 366 | grepstart grepwhile |
| 367 | mapstart mapwhile |
| 368 | enteriter iter |
| 369 | enterloop leaveloop unstack |
| 370 | last next redo |
| 371 | goto |
| 372 | |
| 373 | =item :base_io |
| 374 | |
| 375 | These ops enable I<filehandle> (rather than filename) based input and |
| 376 | output. These are safe on the assumption that only pre-existing |
| 377 | filehandles are available for use. To create new filehandles other ops |
| 378 | such as open would need to be enabled. |
| 379 | |
| 380 | readline rcatline getc read |
| 381 | |
| 382 | formline enterwrite leavewrite |
| 383 | |
| 384 | print sysread syswrite send recv |
| 385 | |
| 386 | eof tell seek sysseek |
| 387 | |
| 388 | readdir telldir seekdir rewinddir |
| 389 | |
| 390 | =item :base_orig |
| 391 | |
| 392 | These are a hotchpotch of opcodes still waiting to be considered |
| 393 | |
| 394 | gvsv gv gelem |
| 395 | |
| 396 | padsv padav padhv padany |
| 397 | |
| 398 | rv2gv refgen srefgen ref |
| 399 | |
| 400 | bless -- could be used to change ownership of objects (reblessing) |
| 401 | |
| 402 | pushre regcmaybe regcreset regcomp subst substcont |
| 403 | |
| 404 | sprintf prtf -- can core dump |
| 405 | |
| 406 | crypt |
| 407 | |
| 408 | tie untie |
| 409 | |
| 410 | dbmopen dbmclose |
| 411 | sselect select |
| 412 | pipe_op sockpair |
| 413 | |
| 414 | getppid getpgrp setpgrp getpriority setpriority localtime gmtime |
| 415 | |
| 416 | entertry leavetry -- can be used to 'hide' fatal errors |
| 417 | |
| 418 | custom -- where should this go |
| 419 | |
| 420 | =item :base_math |
| 421 | |
| 422 | These ops are not included in :base_core because of the risk of them being |
| 423 | used to generate floating point exceptions (which would have to be caught |
| 424 | using a $SIG{FPE} handler). |
| 425 | |
| 426 | atan2 sin cos exp log sqrt |
| 427 | |
| 428 | These ops are not included in :base_core because they have an effect |
| 429 | beyond the scope of the compartment. |
| 430 | |
| 431 | rand srand |
| 432 | |
| 433 | =item :base_thread |
| 434 | |
| 435 | These ops are related to multi-threading. |
| 436 | |
| 437 | lock threadsv |
| 438 | |
| 439 | =item :default |
| 440 | |
| 441 | A handy tag name for a I<reasonable> default set of ops. (The current ops |
| 442 | allowed are unstable while development continues. It will change.) |
| 443 | |
| 444 | :base_core :base_mem :base_loop :base_io :base_orig :base_thread |
| 445 | |
| 446 | If safety matters to you (and why else would you be using the Opcode module?) |
| 447 | then you should not rely on the definition of this, or indeed any other, optag! |
| 448 | |
| 449 | |
| 450 | =item :filesys_read |
| 451 | |
| 452 | stat lstat readlink |
| 453 | |
| 454 | ftatime ftblk ftchr ftctime ftdir fteexec fteowned fteread |
| 455 | ftewrite ftfile ftis ftlink ftmtime ftpipe ftrexec ftrowned |
| 456 | ftrread ftsgid ftsize ftsock ftsuid fttty ftzero ftrwrite ftsvtx |
| 457 | |
| 458 | fttext ftbinary |
| 459 | |
| 460 | fileno |
| 461 | |
| 462 | =item :sys_db |
| 463 | |
| 464 | ghbyname ghbyaddr ghostent shostent ehostent -- hosts |
| 465 | gnbyname gnbyaddr gnetent snetent enetent -- networks |
| 466 | gpbyname gpbynumber gprotoent sprotoent eprotoent -- protocols |
| 467 | gsbyname gsbyport gservent sservent eservent -- services |
| 468 | |
| 469 | gpwnam gpwuid gpwent spwent epwent getlogin -- users |
| 470 | ggrnam ggrgid ggrent sgrent egrent -- groups |
| 471 | |
| 472 | =item :browse |
| 473 | |
| 474 | A handy tag name for a I<reasonable> default set of ops beyond the |
| 475 | :default optag. Like :default (and indeed all the other optags) its |
| 476 | current definition is unstable while development continues. It will change. |
| 477 | |
| 478 | The :browse tag represents the next step beyond :default. It it a |
| 479 | superset of the :default ops and adds :filesys_read the :sys_db. |
| 480 | The intent being that scripts can access more (possibly sensitive) |
| 481 | information about your system but not be able to change it. |
| 482 | |
| 483 | :default :filesys_read :sys_db |
| 484 | |
| 485 | =item :filesys_open |
| 486 | |
| 487 | sysopen open close |
| 488 | umask binmode |
| 489 | |
| 490 | open_dir closedir -- other dir ops are in :base_io |
| 491 | |
| 492 | =item :filesys_write |
| 493 | |
| 494 | link unlink rename symlink truncate |
| 495 | |
| 496 | mkdir rmdir |
| 497 | |
| 498 | utime chmod chown |
| 499 | |
| 500 | fcntl -- not strictly filesys related, but possibly as dangerous? |
| 501 | |
| 502 | =item :subprocess |
| 503 | |
| 504 | backtick system |
| 505 | |
| 506 | fork |
| 507 | |
| 508 | wait waitpid |
| 509 | |
| 510 | glob -- access to Cshell via <`rm *`> |
| 511 | |
| 512 | =item :ownprocess |
| 513 | |
| 514 | exec exit kill |
| 515 | |
| 516 | time tms -- could be used for timing attacks (paranoid?) |
| 517 | |
| 518 | =item :others |
| 519 | |
| 520 | This tag holds groups of assorted specialist opcodes that don't warrant |
| 521 | having optags defined for them. |
| 522 | |
| 523 | SystemV Interprocess Communications: |
| 524 | |
| 525 | msgctl msgget msgrcv msgsnd |
| 526 | |
| 527 | semctl semget semop |
| 528 | |
| 529 | shmctl shmget shmread shmwrite |
| 530 | |
| 531 | =item :still_to_be_decided |
| 532 | |
| 533 | chdir |
| 534 | flock ioctl |
| 535 | |
| 536 | socket getpeername ssockopt |
| 537 | bind connect listen accept shutdown gsockopt getsockname |
| 538 | |
| 539 | sleep alarm -- changes global timer state and signal handling |
| 540 | sort -- assorted problems including core dumps |
| 541 | tied -- can be used to access object implementing a tie |
| 542 | pack unpack -- can be used to create/use memory pointers |
| 543 | |
| 544 | entereval -- can be used to hide code from initial compile |
| 545 | require dofile |
| 546 | |
| 547 | caller -- get info about calling environment and args |
| 548 | |
| 549 | reset |
| 550 | |
| 551 | dbstate -- perl -d version of nextstate(ment) opcode |
| 552 | |
| 553 | =item :dangerous |
| 554 | |
| 555 | This tag is simply a bucket for opcodes that are unlikely to be used via |
| 556 | a tag name but need to be tagged for completeness and documentation. |
| 557 | |
| 558 | syscall dump chroot |
| 559 | |
| 560 | |
| 561 | =back |
| 562 | |
| 563 | =head1 SEE ALSO |
| 564 | |
| 565 | ops(3) -- perl pragma interface to Opcode module. |
| 566 | |
| 567 | Safe(3) -- Opcode and namespace limited execution compartments |
| 568 | |
| 569 | =head1 AUTHORS |
| 570 | |
| 571 | Originally designed and implemented by Malcolm Beattie, |
| 572 | mbeattie@sable.ox.ac.uk as part of Safe version 1. |
| 573 | |
| 574 | Split out from Safe module version 1, named opcode tags and other |
| 575 | changes added by Tim Bunce. |
| 576 | |
| 577 | =cut |
| 578 | |