1/* Part of SWI-Prolog 2 3 Author: Jan Wielemaker 4 E-mail: J.Wielemaker@vu.nl 5 WWW: http://www.swi-prolog.org 6 Copyright (c) 2013-2022, VU University Amsterdam 7 CWI, Amsterdam 8 SWI-Prolog Solutions b.v 9 All rights reserved. 10 11 Redistribution and use in source and binary forms, with or without 12 modification, are permitted provided that the following conditions 13 are met: 14 15 1. Redistributions of source code must retain the above copyright 16 notice, this list of conditions and the following disclaimer. 17 18 2. Redistributions in binary form must reproduce the above copyright 19 notice, this list of conditions and the following disclaimer in 20 the documentation and/or other materials provided with the 21 distribution. 22 23 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 24 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 25 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 26 FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 27 COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 28 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 29 BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 30 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 31 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 33 ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 34 POSSIBILITY OF SUCH DAMAGE. 35*/ 36 37:- module(sandbox, 38 [ safe_goal/1, % :Goal 39 safe_call/1 % :Goal 40 ]). 41:- use_module(library(apply_macros),[expand_phrase/2]). 42:- use_module(library(apply),[maplist/2]). 43:- use_module(library(assoc),[empty_assoc/1,get_assoc/3,put_assoc/4]). 44:- use_module(library(debug),[debug/3,debugging/1]). 45:- use_module(library(error), 46 [ must_be/2, 47 instantiation_error/1, 48 type_error/2, 49 permission_error/3 50 ]). 51:- use_module(library(lists),[append/3]). 52:- use_module(library(prolog_format),[format_types/2]). 53 54:- multifile 55 safe_primitive/1, % Goal 56 safe_meta_predicate/1, % Name/Arity 57 safe_meta/2, % Goal, Calls 58 safe_meta/3, % Goal, Context, Calls 59 safe_global_variable/1, % Name 60 safe_directive/1, % Module:Goal 61 safe_prolog_flag/2. % +Name, +Value 62 63% :- debug(sandbox).
79:- meta_predicate
80 safe_goal(),
81 safe_call().
93safe_call(Goal0) :-
94 expand_goal(Goal0, Goal),
95 safe_goal(Goal),
96 call(Goal).120safe_goal(M:Goal) :- 121 empty_assoc(Safe0), 122 catch(safe(Goal, M, [], Safe0, _), E, true), 123 !, 124 nb_delete(sandbox_last_error), 125 ( var(E) 126 -> true 127 ; throw(E) 128 ). 129safe_goal(_) :- 130 nb_current(sandbox_last_error, E), 131 !, 132 nb_delete(sandbox_last_error), 133 throw(E). 134safe_goal(G) :- 135 debug(sandbox(fail), 'safe_goal/1 failed for ~p', [G]), 136 throw(error(instantiation_error, sandbox(G, []))).
143safe(V, _, Parents, _, _) :- 144 var(V), 145 !, 146 Error = error(instantiation_error, sandbox(V, Parents)), 147 nb_setval(sandbox_last_error, Error), 148 throw(Error). 149safe(M:G, _, Parents, Safe0, Safe) :- 150 !, 151 must_be(atom, M), 152 must_be(callable, G), 153 known_module(M:G, Parents), 154 ( predicate_property(M:G, imported_from(M2)) 155 -> true 156 ; M2 = M 157 ), 158 ( ( safe_primitive(M2:G) 159 ; safe_primitive(G), 160 predicate_property(G, iso) 161 ) 162 -> Safe = Safe0 163 ; ( predicate_property(M:G, exported) 164 ; predicate_property(M:G, public) 165 ; predicate_property(M:G, multifile) 166 ; predicate_property(M:G, iso) 167 ; memberchk(M:_, Parents) 168 ) 169 -> safe(G, M, Parents, Safe0, Safe) 170 ; throw(error(permission_error(call, sandboxed, M:G), 171 sandbox(M:G, Parents))) 172 ). 173safe(G, _, Parents, _, _) :- 174 debugging(sandbox(show)), 175 length(Parents, Level), 176 debug(sandbox(show), '[~D] SAFE ~q?', [Level, G]), 177 fail. 178safe(G, _, Parents, Safe, Safe) :- 179 catch(safe_primitive(G), 180 error(instantiation_error, _), 181 rethrow_instantition_error([G|Parents])), 182 predicate_property(G, iso), 183 !. 184safe(G, M, Parents, Safe, Safe) :- 185 known_module(M:G, Parents), 186 ( predicate_property(M:G, imported_from(M2)) 187 -> true 188 ; M2 = M 189 ), 190 ( catch(safe_primitive(M2:G), 191 error(instantiation_error, _), 192 rethrow_instantition_error([M2:G|Parents])) 193 ; predicate_property(M2:G, number_of_rules(0)) 194 ), 195 !. 196safe(G, M, Parents, Safe0, Safe) :- 197 predicate_property(G, iso), 198 safe_meta_call(G, M, Called), 199 !, 200 add_iso_parent(G, Parents, Parents1), 201 safe_list(Called, M, Parents1, Safe0, Safe). 202safe(G, M, Parents, Safe0, Safe) :- 203 ( predicate_property(M:G, imported_from(M2)) 204 -> true 205 ; M2 = M 206 ), 207 safe_meta_call(M2:G, M, Called), 208 !, 209 safe_list(Called, M, Parents, Safe0, Safe). 210safe(G, M, Parents, Safe0, Safe) :- 211 goal_id(M:G, Id, Gen), 212 ( get_assoc(Id, Safe0, _) 213 -> Safe = Safe0 214 ; put_assoc(Id, Safe0, true, Safe1), 215 ( Gen == M:G 216 -> safe_clauses(Gen, M, [Id|Parents], Safe1, Safe) 217 ; catch(safe_clauses(Gen, M, [Id|Parents], Safe1, Safe), 218 error(instantiation_error, Ctx), 219 unsafe(Parents, Ctx)) 220 ) 221 ), 222 !. 223safe(G, M, Parents, _, _) :- 224 debug(sandbox(fail), 225 'safe/1 failed for ~p (parents:~p)', [M:G, Parents]), 226 fail. 227 228unsafe(Parents, Var) :- 229 var(Var), 230 !, 231 nb_setval(sandbox_last_error, 232 error(instantiation_error, sandbox(_, Parents))), 233 fail. 234unsafe(_Parents, Ctx) :- 235 Ctx = sandbox(_,_), 236 nb_setval(sandbox_last_error, 237 error(instantiation_error, Ctx)), 238 fail. 239 240rethrow_instantition_error(Parents) :- 241 throw(error(instantiation_error, sandbox(_, Parents))). 242 243safe_clauses(G, M, Parents, Safe0, Safe) :- 244 predicate_property(M:G, interpreted), 245 def_module(M:G, MD:QG), 246 \+ compiled(MD:QG), 247 !, 248 findall(Ref-Body, clause(MD:, Body, Ref), Bodies), 249 safe_bodies(Bodies, MD, Parents, Safe0, Safe). 250safe_clauses(G, M, [_|Parents], _, _) :- 251 predicate_property(M:G, visible), 252 !, 253 throw(error(permission_error(call, sandboxed, G), 254 sandbox(M:G, Parents))). 255safe_clauses(_, _, [G|Parents], _, _) :- 256 throw(error(existence_error(procedure, G), 257 sandbox(G, Parents))). 258 259compiled(system:(@(_,_))). 260 261known_module(M:_, _) :- 262 current_module(M), 263 !. 264known_module(M:G, Parents) :- 265 throw(error(permission_error(call, sandboxed, M:G), 266 sandbox(M:G, Parents))). 267 268add_iso_parent(G, Parents, Parents) :- 269 is_control(G), 270 !. 271add_iso_parent(G, Parents, [G|Parents]). 272 273is_control((_,_)). 274is_control((_;_)). 275is_control((_->_)). 276is_control((_*->_)). 277is_control(\+(_)).
286safe_bodies([], _, _, Safe, Safe). 287safe_bodies([Ref-H|T], M, Parents, Safe0, Safe) :- 288 ( H = M2:H2, nonvar(M2), 289 clause_property(Ref, module(M2)) 290 -> copy_term(H2, H3), 291 CM = M2 292 ; copy_term(H, H3), 293 CM = M 294 ), 295 safe(H3, CM, Parents, Safe0, Safe1), 296 safe_bodies(T, M, Parents, Safe1, Safe). 297 298def_module(M:G, MD:QG) :- 299 predicate_property(M:G, imported_from(MD)), 300 !, 301 meta_qualify(MD:G, M, QG). 302def_module(M:G, M:QG) :- 303 meta_qualify(M:G, M, QG).
311safe_list([], _, _, Safe, Safe). 312safe_list([H|T], M, Parents, Safe0, Safe) :- 313 ( H = M2:H2, 314 M == M2 % in our context 315 -> copy_term(H2, H3) 316 ; copy_term(H, H3) % cross-module call 317 ), 318 safe(H3, M, Parents, Safe0, Safe1), 319 safe_list(T, M, Parents, Safe1, Safe).
325meta_qualify(MD:G, M, QG) :- 326 predicate_property(MD:G, meta_predicate(Head)), 327 !, 328 G =.. [Name|Args], 329 Head =.. [_|Q], 330 qualify_args(Q, M, Args, QArgs), 331 QG =.. [Name|QArgs]. 332meta_qualify(_:G, _, G). 333 334qualify_args([], _, [], []). 335qualify_args([H|T], M, [A|AT], [Q|QT]) :- 336 qualify_arg(H, M, A, Q), 337 qualify_args(T, M, AT, QT). 338 339qualify_arg(S, M, A, Q) :- 340 q_arg(S), 341 !, 342 qualify(A, M, Q). 343qualify_arg(_, _, A, A). 344 345q_arg(I) :- integer(I), !. 346q_arg(:). 347q_arg(^). 348q_arg(//). 349 350qualify(A, M, MZ:Q) :- 351 strip_module(M:A, MZ, Q).
363goal_id(M:Goal, M:Id, Gen) :- 364 !, 365 goal_id(Goal, Id, Gen). 366goal_id(Var, _, _) :- 367 var(Var), 368 !, 369 instantiation_error(Var). 370goal_id(Atom, Atom, Atom) :- 371 atom(Atom), 372 !. 373goal_id(Term, _, _) :- 374 \+ compound(Term), 375 !, 376 type_error(callable, Term). 377goal_id(Term, Skolem, Gen) :- % most general form 378 compound_name_arity(Term, Name, Arity), 379 compound_name_arity(Skolem, Name, Arity), 380 compound_name_arity(Gen, Name, Arity), 381 copy_goal_args(1, Term, Skolem, Gen), 382 ( Gen =@= Term 383 -> ! % No more specific one; we can commit 384 ; true 385 ), 386 numbervars(Skolem, 0, _). 387goal_id(Term, Skolem, Term) :- % most specific form 388 debug(sandbox(specify), 'Retrying with ~p', [Term]), 389 copy_term(Term, Skolem), 390 numbervars(Skolem, 0, _).
397copy_goal_args(I, Term, Skolem, Gen) :- 398 arg(I, Term, TA), 399 !, 400 arg(I, Skolem, SA), 401 arg(I, Gen, GA), 402 copy_goal_arg(TA, SA, GA), 403 I2 is I + 1, 404 copy_goal_args(I2, Term, Skolem, Gen). 405copy_goal_args(_, _, _, _). 406 407copy_goal_arg(Arg, SArg, Arg) :- 408 copy_goal_arg(Arg), 409 !, 410 copy_term(Arg, SArg). 411copy_goal_arg(_, _, _). 412 413copy_goal_arg(Var) :- var(Var), !, fail. 414copy_goal_arg(_:_).
426term_expansion(safe_primitive(Goal), Term) :- 427 ( verify_safe_declaration(Goal) 428 -> Term = safe_primitive(Goal) 429 ; Term = [] 430 ). 431term_expansion((safe_primitive(Goal) :- Body), Term) :- 432 ( verify_safe_declaration(Goal) 433 -> Term = (safe_primitive(Goal) :- Body) 434 ; Term = [] 435 ). 436 437systemterm_expansion(sandbox:safe_primitive(Goal), Term) :- 438 \+ current_prolog_flag(xref, true), 439 ( verify_safe_declaration(Goal) 440 -> Term = sandbox:safe_primitive(Goal) 441 ; Term = [] 442 ). 443systemterm_expansion((sandbox:safe_primitive(Goal) :- Body), Term) :- 444 \+ current_prolog_flag(xref, true), 445 ( verify_safe_declaration(Goal) 446 -> Term = (sandbox:safe_primitive(Goal) :- Body) 447 ; Term = [] 448 ). 449 450verify_safe_declaration(Var) :- 451 var(Var), 452 !, 453 instantiation_error(Var). 454verify_safe_declaration(Module:Goal) :- 455 !, 456 must_be(atom, Module), 457 must_be(callable, Goal), 458 ( ok_meta(Module:Goal) 459 -> true 460 ; ( predicate_property(Module:Goal, visible) 461 -> true 462 ; predicate_property(Module:Goal, foreign) 463 ), 464 \+ predicate_property(Module:Goal, imported_from(_)), 465 \+ predicate_property(Module:Goal, meta_predicate(_)) 466 -> true 467 ; permission_error(declare, safe_goal, Module:Goal) 468 ). 469verify_safe_declaration(Goal) :- 470 must_be(callable, Goal), 471 ( predicate_property(system:Goal, iso), 472 \+ predicate_property(system:Goal, meta_predicate()) 473 -> true 474 ; permission_error(declare, safe_goal, Goal) 475 ). 476 477ok_meta(system:assert(_)). 478ok_meta(system:load_files(_,_)). 479ok_meta(system:use_module(_,_)). 480ok_meta(system:use_module(_)). 481ok_meta('$syspreds':predicate_property(_,_)). 482 483verify_predefined_safe_declarations :- 484 forall(clause(safe_primitive(Goal), _Body, Ref), 485 ( E = error(F,_), 486 catch(verify_safe_declaration(Goal), E, true), 487 ( nonvar(F) 488 -> clause_property(Ref, file(File)), 489 clause_property(Ref, line_count(Line)), 490 print_message(error, bad_safe_declaration(Goal, File, Line)) 491 ; true 492 ) 493 )). 494 495:- initialization(verify_predefined_safe_declarations, now).
509% First, all ISO system predicates that are considered safe 510 511safe_primitive(true). 512safe_primitive(fail). 513safe_primitive(system:false). 514safe_primitive(repeat). 515safe_primitive(!). 516 % types 517safe_primitive(var(_)). 518safe_primitive(nonvar(_)). 519safe_primitive(system:attvar(_)). 520safe_primitive(integer(_)). 521safe_primitive(float(_)). 522:- if(current_predicate(rational/1)). 523safe_primitive(system:rational(_)). 524safe_primitive(system:rational(_,_,_)). 525:- endif. 526safe_primitive(number(_)). 527safe_primitive(atom(_)). 528safe_primitive(system:blob(_,_)). 529safe_primitive(system:string(_)). 530safe_primitive(atomic(_)). 531safe_primitive(compound(_)). 532safe_primitive(callable(_)). 533safe_primitive(ground(_)). 534safe_primitive(system:nonground(_,_)). 535safe_primitive(system:cyclic_term(_)). 536safe_primitive(acyclic_term(_)). 537safe_primitive(system:is_stream(_)). 538safe_primitive(system:'$is_char'(_)). 539safe_primitive(system:'$is_char_code'(_)). 540safe_primitive(system:'$is_char_list'(_,_)). 541safe_primitive(system:'$is_code_list'(_,_)). 542 % ordering 543safe_primitive(@>(_,_)). 544safe_primitive(@>=(_,_)). 545safe_primitive(==(_,_)). 546safe_primitive(@<(_,_)). 547safe_primitive(@=<(_,_)). 548safe_primitive(compare(_,_,_)). 549safe_primitive(sort(_,_)). 550safe_primitive(keysort(_,_)). 551safe_primitive(system: =@=(_,_)). 552safe_primitive(system:'$btree_find_node'(_,_,_,_,_)). 553 554 % unification and equivalence 555safe_primitive(=(_,_)). 556safe_primitive(\=(_,_)). 557safe_primitive(system:'?='(_,_)). 558safe_primitive(system:unifiable(_,_,_)). 559safe_primitive(unify_with_occurs_check(_,_)). 560safe_primitive(\==(_,_)). 561 % arithmetic 562safe_primitive(is(_,_)). 563safe_primitive(>(_,_)). 564safe_primitive(>=(_,_)). 565safe_primitive(=:=(_,_)). 566safe_primitive(=\=(_,_)). 567safe_primitive(=<(_,_)). 568safe_primitive(<(_,_)). 569:- if(current_prolog_flag(bounded, false)). 570safe_primitive(system:nth_integer_root_and_remainder(_,_,_,_)). 571:- endif. 572 573 % term-handling 574safe_primitive(arg(_,_,_)). 575safe_primitive(system:setarg(_,_,_)). 576safe_primitive(system:nb_setarg(_,_,_)). 577safe_primitive(system:nb_linkarg(_,_,_)). 578safe_primitive(functor(_,_,_)). 579safe_primitive(system:functor(_,_,_,_)). 580safe_primitive(_ =.. _). 581safe_primitive(system:compound_name_arity(_,_,_)). 582safe_primitive(system:compound_name_arguments(_,_,_)). 583safe_primitive(system:'$filled_array'(_,_,_,_)). 584safe_primitive(copy_term(_,_)). 585safe_primitive(system:copy_term(_,_,_,_)). 586safe_primitive(system:duplicate_term(_,_)). 587safe_primitive(system:copy_term_nat(_,_)). 588safe_primitive(system:size_abstract_term(_,_,_)). 589safe_primitive(numbervars(_,_,_)). 590safe_primitive(system:numbervars(_,_,_,_)). 591safe_primitive(subsumes_term(_,_)). 592safe_primitive(system:term_hash(_,_)). 593safe_primitive(system:term_hash(_,_,_,_)). 594safe_primitive(system:variant_sha1(_,_)). 595safe_primitive(system:variant_hash(_,_)). 596safe_primitive(system:'$term_size'(_,_,_)). 597 598 % dicts 599safe_primitive(system:is_dict(_)). 600safe_primitive(system:is_dict(_,_)). 601safe_primitive(system:get_dict(_,_,_)). 602safe_primitive(system:get_dict(_,_,_,_,_)). 603safe_primitive(system:'$get_dict_ex'(_,_,_)). 604safe_primitive(system:dict_create(_,_,_)). 605safe_primitive(system:dict_pairs(_,_,_)). 606safe_primitive(system:put_dict(_,_,_)). 607safe_primitive(system:put_dict(_,_,_,_)). 608safe_primitive(system:del_dict(_,_,_,_)). 609safe_primitive(system:select_dict(_,_,_)). 610safe_primitive(system:b_set_dict(_,_,_)). 611safe_primitive(system:nb_set_dict(_,_,_)). 612safe_primitive(system:nb_link_dict(_,_,_)). 613safe_primitive(system:(:<(_,_))). 614safe_primitive(system:(>:<(_,_))). 615 % atoms 616safe_primitive(atom_chars(_, _)). 617safe_primitive(atom_codes(_, _)). 618safe_primitive(sub_atom(_,_,_,_,_)). 619safe_primitive(atom_concat(_,_,_)). 620safe_primitive(atom_length(_,_)). 621safe_primitive(char_code(_,_)). 622safe_primitive(system:name(_,_)). 623safe_primitive(system:atomic_concat(_,_,_)). 624safe_primitive(system:atomic_list_concat(_,_)). 625safe_primitive(system:atomic_list_concat(_,_,_)). 626safe_primitive(system:downcase_atom(_,_)). 627safe_primitive(system:upcase_atom(_,_)). 628safe_primitive(system:char_type(_,_)). 629safe_primitive(system:normalize_space(_,_)). 630safe_primitive(system:sub_atom_icasechk(_,_,_)). 631 % numbers 632safe_primitive(number_codes(_,_)). 633safe_primitive(number_chars(_,_)). 634safe_primitive(system:atom_number(_,_)). 635safe_primitive(system:code_type(_,_)). 636 % strings 637safe_primitive(system:atom_string(_,_)). 638safe_primitive(system:number_string(_,_)). 639safe_primitive(system:string_chars(_, _)). 640safe_primitive(system:string_codes(_, _)). 641safe_primitive(system:string_code(_,_,_)). 642safe_primitive(system:sub_string(_,_,_,_,_)). 643safe_primitive(system:split_string(_,_,_,_)). 644safe_primitive(system:atomics_to_string(_,_,_)). 645safe_primitive(system:atomics_to_string(_,_)). 646safe_primitive(system:string_concat(_,_,_)). 647safe_primitive(system:string_length(_,_)). 648safe_primitive(system:string_lower(_,_)). 649safe_primitive(system:string_upper(_,_)). 650safe_primitive(system:term_string(_,_)). 651safe_primitive('$syspreds':term_string(_,_,_)). 652 % Lists 653safe_primitive(length(_,_)). 654 % exceptions 655safe_primitive(throw(_)). 656safe_primitive(system:abort). 657 % misc 658safe_primitive(current_prolog_flag(_,_)). 659safe_primitive(current_op(_,_,_)). 660safe_primitive(system:sleep(_)). 661safe_primitive(system:thread_self(_)). 662safe_primitive(system:get_time(_)). 663safe_primitive(system:statistics(_,_)). 664safe_primitive(system:thread_statistics(Id,_,_)) :- 665 ( var(Id) 666 -> instantiation_error(Id) 667 ; thread_self(Id) 668 ). 669safe_primitive(system:thread_property(Id,_)) :- 670 ( var(Id) 671 -> instantiation_error(Id) 672 ; thread_self(Id) 673 ). 674safe_primitive(system:format_time(_,_,_)). 675safe_primitive(system:format_time(_,_,_,_)). 676safe_primitive(system:date_time_stamp(_,_)). 677safe_primitive(system:stamp_date_time(_,_,_)). 678safe_primitive(system:strip_module(_,_,_)). 679safe_primitive('$messages':message_to_string(_,_)). 680safe_primitive(system:import_module(_,_)). 681safe_primitive(system:file_base_name(_,_)). 682safe_primitive(system:file_directory_name(_,_)). 683safe_primitive(system:file_name_extension(_,_,_)). 684 685safe_primitive(clause(H,_)) :- safe_clause(H). 686safe_primitive(asserta(X)) :- safe_assert(X). 687safe_primitive(assertz(X)) :- safe_assert(X). 688safe_primitive(retract(X)) :- safe_assert(X). 689safe_primitive(retractall(X)) :- safe_assert(X). 690safe_primitive('$dcg':dcg_translate_rule(_,_)). 691safe_primitive('$syspreds':predicate_property(Pred, _)) :- 692 nonvar(Pred), 693 Pred \= (_:_). 694 695% We need to do data flow analysis to find the tag of the 696% target key before we can conclude that functions on dicts 697% are safe. 698safe_primitive('$dicts':'.'(_,K,_)) :- atom(K). 699safe_primitive('$dicts':'.'(_,K,_)) :- 700 ( nonvar(K) 701 -> dict_built_in(K) 702 ; instantiation_error(K) 703 ). 704 705dict_built_in(get(_)). 706dict_built_in(put(_)). 707dict_built_in(put(_,_)). 708 709% The non-ISO system predicates. These can be redefined, so we must 710% be careful to ensure the system ones are used. 711 712safe_primitive(system:false). 713safe_primitive(system:cyclic_term(_)). 714safe_primitive(system:msort(_,_)). 715safe_primitive(system:sort(_,_,_,_)). 716safe_primitive(system:between(_,_,_)). 717safe_primitive(system:succ(_,_)). 718safe_primitive(system:plus(_,_,_)). 719safe_primitive(system:float_class(_,_)). 720safe_primitive(system:term_variables(_,_)). 721safe_primitive(system:term_variables(_,_,_)). 722safe_primitive(system:'$term_size'(_,_,_)). 723safe_primitive(system:atom_to_term(_,_,_)). 724safe_primitive(system:term_to_atom(_,_)). 725safe_primitive(system:atomic_list_concat(_,_,_)). 726safe_primitive(system:atomic_list_concat(_,_)). 727safe_primitive(system:downcase_atom(_,_)). 728safe_primitive(system:upcase_atom(_,_)). 729safe_primitive(system:is_list(_)). 730safe_primitive(system:memberchk(_,_)). 731safe_primitive(system:'$skip_list'(_,_,_)). 732 % attributes 733safe_primitive(system:get_attr(_,_,_)). 734safe_primitive(system:get_attrs(_,_)). 735safe_primitive(system:term_attvars(_,_)). 736safe_primitive(system:del_attr(_,_)). 737safe_primitive(system:del_attrs(_)). 738safe_primitive('$attvar':copy_term(_,_,_)). 739 % globals 740safe_primitive(system:b_getval(_,_)). 741safe_primitive(system:b_setval(Var,_)) :- 742 safe_global_var(Var). 743safe_primitive(system:nb_getval(_,_)). 744safe_primitive('$syspreds':nb_setval(Var,_)) :- 745 safe_global_var(Var). 746safe_primitive(system:nb_linkval(Var,_)) :- 747 safe_global_var(Var). 748safe_primitive(system:nb_current(_,_)). 749 % database 750safe_primitive(system:assert(X)) :- 751 safe_assert(X). 752 % Output 753safe_primitive(system:writeln(_)). 754safe_primitive('$messages':print_message(_,_)). 755 756 % Stack limits (down) 757safe_primitive('$syspreds':set_prolog_stack(Stack, limit(ByteExpr))) :- 758 nonvar(Stack), 759 stack_name(Stack), 760 catch(Bytes is ByteExpr, _, fail), 761 prolog_stack_property(Stack, limit(Current)), 762 Bytes =< Current. 763 764stack_name(global). 765stack_name(local). 766stack_name(trail). 767 768safe_primitive('$tabling':abolish_all_tables). 769safe_primitive('$tabling':'$wrap_tabled'(Module:_Head, _Mode)) :- 770 prolog_load_context(module, Module), 771 !. 772safe_primitive('$tabling':'$moded_wrap_tabled'(Module:_Head,_,_,_,_)) :- 773 prolog_load_context(module, Module), 774 !. 775 776 777% use_module/1. We only allow for .pl files that are loaded from 778% relative paths that do not contain /../ 779 780safe_primitive(system:use_module(Spec, _Import)) :- 781 safe_primitive(system:use_module(Spec)). 782safe_primitive(system:load_files(Spec, Options)) :- 783 safe_primitive(system:use_module(Spec)), 784 maplist(safe_load_file_option, Options). 785safe_primitive(system:use_module(Spec)) :- 786 ground(Spec), 787 ( atom(Spec) 788 -> Path = Spec 789 ; Spec =.. [_Alias, Segments], 790 phrase(segments_to_path(Segments), List), 791 atomic_list_concat(List, Path) 792 ), 793 \+ is_absolute_file_name(Path), 794 \+ sub_atom(Path, _, _, _, '/../'), 795 absolute_file_name(Spec, AbsFile, 796 [ access(read), 797 file_type(prolog), 798 file_errors(fail) 799 ]), 800 file_name_extension(_, Ext, AbsFile), 801 save_extension(Ext). 802 803% support predicates for safe_primitive, validating the safety of 804% arguments to certain goals. 805 806segments_to_path(A/B) --> 807 !, 808 segments_to_path(A), 809 [/], 810 segments_to_path(B). 811segments_to_path(X) --> 812 [X]. 813 814save_extension(pl). 815 816safe_load_file_option(if(changed)). 817safe_load_file_option(if(not_loaded)). 818safe_load_file_option(must_be_module(_)). 819safe_load_file_option(optimise(_)). 820safe_load_file_option(silent(_)).
assert(Term) is safe, which means it asserts in the
current module. Cross-module asserts are considered unsafe. We
only allow for adding facts. In theory, we could also allow for
rules if we prove the safety of the body.829safe_assert(C) :- cyclic_term(C), !, fail. 830safe_assert(X) :- var(X), !, fail. 831safe_assert(_Head:-_Body) :- !, fail. 832safe_assert(_:_) :- !, fail. 833safe_assert(_).
841safe_clause(H) :- var(H), !. 842safe_clause(_:_) :- !, fail. 843safe_clause(_).
851safe_global_var(Name) :- 852 var(Name), 853 !, 854 instantiation_error(Name). 855safe_global_var(Name) :- 856 safe_global_variable(Name).
868safe_meta(system:put_attr(V,M,A), Called) :- 869 !, 870 ( atom(M) 871 -> attr_hook_predicates([ attr_unify_hook(A, _), 872 attribute_goals(V,_,_), 873 project_attributes(_,_) 874 ], M, Called) 875 ; instantiation_error(M) 876 ). 877safe_meta(system:with_output_to(Output, G), [G]) :- 878 safe_output(Output), 879 !. 880safe_meta(system:format(Format, Args), Calls) :- 881 format_calls(Format, Args, Calls). 882safe_meta(system:format(Output, Format, Args), Calls) :- 883 safe_output(Output), 884 format_calls(Format, Args, Calls). 885safe_meta(prolog_debug:debug(_Term, Format, Args), Calls) :- 886 format_calls(Format, Args, Calls). 887safe_meta(system:set_prolog_flag(Flag, Value), []) :- 888 atom(Flag), 889 safe_prolog_flag(Flag, Value). 890safe_meta('$attvar':freeze(_Var,Goal), [Goal]). 891safe_meta(phrase(NT,Xs0,Xs), [Goal]) :- % phrase/2,3 and call_dcg/2,3 892 expand_nt(NT,Xs0,Xs,Goal). 893safe_meta(phrase(NT,Xs0), [Goal]) :- 894 expand_nt(NT,Xs0,[],Goal). 895safe_meta('$dcg':call_dcg(NT,Xs0,Xs), [Goal]) :- 896 expand_nt(NT,Xs0,Xs,Goal). 897safe_meta('$dcg':call_dcg(NT,Xs0), [Goal]) :- 898 expand_nt(NT,Xs0,[],Goal). 899safe_meta('$tabling':abolish_table_subgoals(V), []) :- 900 \+ qualified(V). 901safe_meta('$tabling':current_table(V, _), []) :- 902 \+ qualified(V). 903safe_meta('$tabling':tnot(G), [G]). 904safe_meta('$tabling':not_exists(G), [G]). 905 906qualified(V) :- 907 nonvar(V), 908 V = _:_.
918attr_hook_predicates([], _, []). 919attr_hook_predicates([H|T], M, Called) :- 920 ( predicate_property(M:H, defined) 921 -> Called = [M:H|Rest] 922 ; Called = Rest 923 ), 924 attr_hook_predicates(T, M, Rest).
932expand_nt(NT, _Xs0, _Xs, _NewGoal) :- 933 strip_module(NT, _, Plain), 934 var(Plain), 935 !, 936 instantiation_error(Plain). 937expand_nt(NT, Xs0, Xs, NewGoal) :- 938 dcg_translate_rule((pseudo_nt --> NT), 939 (pseudo_nt(Xs0c,Xsc) :- NewGoal0)), 940 ( var(Xsc), Xsc \== Xs0c 941 -> Xs = Xsc, NewGoal1 = NewGoal0 942 ; NewGoal1 = (NewGoal0, Xsc = Xs) 943 ), 944 ( var(Xs0c) 945 -> Xs0 = Xs0c, 946 NewGoal = NewGoal1 947 ; NewGoal = ( Xs0 = Xs0c, NewGoal1 ) 948 ).
955safe_meta_call(Goal, _, _Called) :- 956 debug(sandbox(meta), 'Safe meta ~p?', [Goal]), 957 fail. 958safe_meta_call(Goal, Context, Called) :- 959 ( safe_meta(Goal, Called) 960 -> true 961 ; safe_meta(Goal, Context, Called) 962 ), 963 !. % call hook 964safe_meta_call(Goal, _, Called) :- 965 Goal = M:Plain, 966 compound(Plain), 967 compound_name_arity(Plain, Name, Arity), 968 safe_meta_predicate(M:Name/Arity), 969 predicate_property(Goal, meta_predicate(Spec)), 970 !, 971 called(Spec, Plain, Called). 972safe_meta_call(M:Goal, _, Called) :- 973 !, 974 generic_goal(Goal, Gen), 975 safe_meta(M:Gen), 976 called(Gen, Goal, Called). 977safe_meta_call(Goal, _, Called) :- 978 generic_goal(Goal, Gen), 979 safe_meta(Gen), 980 called(Gen, Goal, Called). 981 982called(Gen, Goal, Called) :- 983 compound_name_arity(Goal, _, Arity), 984 called(1, Arity, Gen, Goal, Called). 985 986called(I, Arity, Gen, Goal, Called) :- 987 I =< Arity, 988 !, 989 arg(I, Gen, Spec), 990 ( calling_meta_spec(Spec) 991 -> arg(I, Goal, Called0), 992 extend(Spec, Called0, G), 993 Called = [G|Rest] 994 ; Called = Rest 995 ), 996 I2 is I+1, 997 called(I2, Arity, Gen, Goal, Rest). 998called(_, _, _, _, []). 999 1000generic_goal(G, Gen) :- 1001 functor(G, Name, Arity), 1002 functor(Gen, Name, Arity). 1003 1004calling_meta_spec(V) :- var(V), !, fail. 1005calling_meta_spec(I) :- integer(I), !. 1006calling_meta_spec(^). 1007calling_meta_spec(//). 1008 1009 1010extend(^, G, Plain) :- 1011 !, 1012 strip_existential(G, Plain). 1013extend(//, DCG, Goal) :- 1014 !, 1015 ( expand_phrase(call_dcg(DCG,_,_), Goal) 1016 -> true 1017 ; instantiation_error(DCG) % Ask more instantiation. 1018 ). % might not help, but does not harm. 1019extend(0, G, G) :- !. 1020extend(I, M:G0, M:G) :- 1021 !, 1022 G0 =.. List, 1023 length(Extra, I), 1024 append(List, Extra, All), 1025 G =.. All. 1026extend(I, G0, G) :- 1027 G0 =.. List, 1028 length(Extra, I), 1029 append(List, Extra, All), 1030 G =.. All. 1031 1032strip_existential(Var, Var) :- 1033 var(Var), 1034 !. 1035strip_existential(M:G0, M:G) :- 1036 !, 1037 strip_existential(G0, G). 1038strip_existential(_^G0, G) :- 1039 !, 1040 strip_existential(G0, G). 1041strip_existential(G, G).
1045safe_meta((0,0)). 1046safe_meta((0;0)). 1047safe_meta((0->0)). 1048safe_meta(system:(0*->0)). 1049safe_meta(catch(0,*,0)). 1050safe_meta(findall(*,0,*)). 1051safe_meta('$bags':findall(*,0,*,*)). 1052safe_meta(setof(*,^,*)). 1053safe_meta(bagof(*,^,*)). 1054safe_meta('$bags':findnsols(*,*,0,*)). 1055safe_meta('$bags':findnsols(*,*,0,*,*)). 1056safe_meta(system:call_cleanup(0,0)). 1057safe_meta(system:setup_call_cleanup(0,0,0)). 1058safe_meta(system:setup_call_catcher_cleanup(0,0,*,0)). 1059safe_meta('$attvar':call_residue_vars(0,*)). 1060safe_meta('$syspreds':call_with_inference_limit(0,*,*)). 1061safe_meta('$syspreds':call_with_depth_limit(0,*,*)). 1062safe_meta('$syspreds':undo(0)). 1063safe_meta(^(*,0)). 1064safe_meta(\+(0)). 1065safe_meta(call(0)). 1066safe_meta(call(1,*)). 1067safe_meta(call(2,*,*)). 1068safe_meta(call(3,*,*,*)). 1069safe_meta(call(4,*,*,*,*)). 1070safe_meta(call(5,*,*,*,*,*)). 1071safe_meta(call(6,*,*,*,*,*,*)). 1072safe_meta('$tabling':start_tabling(*,0)). 1073safe_meta('$tabling':start_tabling(*,0,*,*)). 1074safe_meta(wfs:call_delays(0,*)).
1081safe_output(Output) :- 1082 var(Output), 1083 !, 1084 instantiation_error(Output). 1085safe_output(atom(_)). 1086safe_output(string(_)). 1087safe_output(codes(_)). 1088safe_output(codes(_,_)). 1089safe_output(chars(_)). 1090safe_output(chars(_,_)). 1091safe_output(current_output). 1092safe_output(current_error).
1098:- public format_calls/3. % used in pengines_io 1099 1100format_calls(Format, _Args, _Calls) :- 1101 var(Format), 1102 !, 1103 instantiation_error(Format). 1104format_calls(Format, Args, Calls) :- 1105 format_types(Format, Types), 1106 ( format_callables(Types, Args, Calls) 1107 -> true 1108 ; throw(error(format_error(Format, Types, Args), _)) 1109 ). 1110 1111format_callables([], [], []). 1112format_callables([callable|TT], [G|TA], [G|TG]) :- 1113 !, 1114 format_callables(TT, TA, TG). 1115format_callables([_|TT], [_|TA], TG) :- 1116 !, 1117 format_callables(TT, TA, TG). 1118 1119 1120 /******************************* 1121 * SAFE COMPILATION HOOKS * 1122 *******************************/ 1123 1124:- multifile 1125 prolog:sandbox_allowed_directive/1, 1126 prolog:sandbox_allowed_goal/1, 1127 prolog:sandbox_allowed_expansion/1.
1133prologsandbox_allowed_directive(Directive) :- 1134 debug(sandbox(directive), 'Directive: ~p', [Directive]), 1135 fail. 1136prologsandbox_allowed_directive(Directive) :- 1137 safe_directive(Directive), 1138 !. 1139prologsandbox_allowed_directive(M:PredAttr) :- 1140 \+ prolog_load_context(module, M), 1141 !, 1142 debug(sandbox(directive), 'Cross-module directive', []), 1143 permission_error(execute, sandboxed_directive, (:- M:PredAttr)). 1144prologsandbox_allowed_directive(M:PredAttr) :- 1145 safe_pattr(PredAttr), 1146 !, 1147 PredAttr =.. [Attr, Preds], 1148 ( safe_pattr(Preds, Attr) 1149 -> true 1150 ; permission_error(execute, sandboxed_directive, (:- M:PredAttr)) 1151 ). 1152prologsandbox_allowed_directive(_:Directive) :- 1153 safe_source_directive(Directive), 1154 !. 1155prologsandbox_allowed_directive(_:Directive) :- 1156 directive_loads_file(Directive, File), 1157 !, 1158 safe_path(File). 1159prologsandbox_allowed_directive(G) :- 1160 safe_goal(G).
Module:Directive (without :- wrapper). In almost all
cases, the implementation must verify that the Module is the
current load context as illustrated below. This check is not
performed by the system to allow for cases where particular
cross-module directives are allowed.
sandbox:safe_directive(M:Directive) :-
prolog_load_context(module, M),
...
1178safe_pattr(dynamic(_)). 1179safe_pattr(thread_local(_)). 1180safe_pattr(volatile(_)). 1181safe_pattr(discontiguous(_)). 1182safe_pattr(multifile(_)). 1183safe_pattr(public(_)). 1184safe_pattr(meta_predicate(_)). 1185safe_pattr(table(_)). 1186safe_pattr(non_terminal(_)). 1187 1188safe_pattr(Var, _) :- 1189 var(Var), 1190 !, 1191 instantiation_error(Var). 1192safe_pattr((A,B), Attr) :- 1193 !, 1194 safe_pattr(A, Attr), 1195 safe_pattr(B, Attr). 1196safe_pattr(M:G, Attr) :- 1197 !, 1198 ( atom(M), 1199 prolog_load_context(module, M) 1200 -> true 1201 ; Goal =.. [Attr,M:G], 1202 permission_error(directive, sandboxed, (:- Goal)) 1203 ). 1204safe_pattr(_, _). 1205 1206safe_source_directive(op(_,_,Name)) :- 1207 !, 1208 ( atom(Name) 1209 -> true 1210 ; is_list(Name), 1211 maplist(atom, Name) 1212 ). 1213safe_source_directive(set_prolog_flag(Flag, Value)) :- 1214 !, 1215 atom(Flag), ground(Value), 1216 safe_prolog_flag(Flag, Value). 1217safe_source_directive(style_check(_)). 1218safe_source_directive(initialization(_)). % Checked at runtime 1219safe_source_directive(initialization(_,_)). % Checked at runtime 1220 1221directive_loads_file(use_module(library(X)), X). 1222directive_loads_file(use_module(library(X), _Imports), X). 1223directive_loads_file(load_files(library(X), _Options), X). 1224directive_loads_file(ensure_loaded(library(X)), X). 1225directive_loads_file(include(X), X). 1226 1227safe_path(X) :- 1228 var(X), 1229 !, 1230 instantiation_error(X). 1231safe_path(X) :- 1232 ( atom(X) 1233 ; string(X) 1234 ), 1235 !, 1236 \+ sub_atom(X, 0, _, 0, '..'), 1237 \+ sub_atom(X, 0, _, _, '/'), 1238 \+ sub_atom(X, 0, _, _, '../'), 1239 \+ sub_atom(X, _, _, 0, '/..'), 1240 \+ sub_atom(X, _, _, _, '/../'). 1241safe_path(A/B) :- 1242 !, 1243 safe_path(A), 1244 safe_path(B).
1256% misc 1257safe_prolog_flag(generate_debug_info, _). 1258safe_prolog_flag(optimise, _). 1259safe_prolog_flag(occurs_check, _). 1260% syntax 1261safe_prolog_flag(var_prefix, _). 1262safe_prolog_flag(double_quotes, _). 1263safe_prolog_flag(back_quotes, _). 1264safe_prolog_flag(rational_syntax, _). 1265% arithmetic 1266safe_prolog_flag(prefer_rationals, _). 1267safe_prolog_flag(float_overflow, _). 1268safe_prolog_flag(float_zero_div, _). 1269safe_prolog_flag(float_undefined, _). 1270safe_prolog_flag(float_underflow, _). 1271safe_prolog_flag(float_rounding, _). 1272safe_prolog_flag(float_rounding, _). 1273safe_prolog_flag(max_rational_size, _). 1274safe_prolog_flag(max_rational_size_action, _). 1275% tabling 1276safe_prolog_flag(max_answers_for_subgoal,_). 1277safe_prolog_flag(max_answers_for_subgoal_action,_). 1278safe_prolog_flag(max_table_answer_size,_). 1279safe_prolog_flag(max_table_answer_size_action,_). 1280safe_prolog_flag(max_table_subgoal_size,_). 1281safe_prolog_flag(max_table_subgoal_size_action,_).
Our assumption is that external expansion rules are coded safely and we only need to be careful if the sandboxed code defines expansion rules.
1297prologsandbox_allowed_expansion(M:G) :- 1298 prolog_load_context(module, M), 1299 !, 1300 debug(sandbox(expansion), 'Expand in ~p: ~p', [M, G]), 1301 safe_goal(M:G). 1302prologsandbox_allowed_expansion(_,_).
1308prologsandbox_allowed_goal(G) :- 1309 safe_goal(G). 1310 1311 1312 /******************************* 1313 * MESSAGES * 1314 *******************************/ 1315 1316:- multifile 1317 prolog:message//1, 1318 prolog:message_context//1, 1319 prolog:error_message//1. 1320 1321prologmessage(error(instantiation_error, Context)) --> 1322 { nonvar(Context), 1323 Context = sandbox(_Goal,Parents), 1324 numbervars(Context, 1, _) 1325 }, 1326 [ 'Sandbox restriction!'-[], nl, 1327 'Could not derive which predicate may be called from'-[] 1328 ], 1329 ( { Parents == [] } 1330 -> [ 'Search space too large'-[] ] 1331 ; callers(Parents, 10) 1332 ). 1333 1334prologmessage_context(sandbox(_G, [])) --> !. 1335prologmessage_context(sandbox(_G, Parents)) --> 1336 [ nl, 'Reachable from:'-[] ], 1337 callers(Parents, 10). 1338 1339callers([], _) --> !. 1340callers(_, 0) --> !. 1341callers([G|Parents], Level) --> 1342 { NextLevel is Level-1 1343 }, 1344 [ nl, '\t ~p'-[G] ], 1345 callers(Parents, NextLevel). 1346 1347prologmessage(bad_safe_declaration(Goal, File, Line)) --> 1348 [ '~w:~d: Invalid safe_primitive/1 declaration: ~p'- 1349 [File, Line, Goal] ]. 1350 1351prologerror_message(format_error(Format, Types, Args)) --> 1352 format_error(Format, Types, Args). 1353 1354format_error(Format, Types, Args) --> 1355 { length(Types, TypeLen), 1356 length(Args, ArgsLen), 1357 ( TypeLen > ArgsLen 1358 -> Problem = 'not enough' 1359 ; Problem = 'too many' 1360 ) 1361 }, 1362 [ 'format(~q): ~w arguments (found ~w, need ~w)'- 1363 [Format, Problem, ArgsLen, TypeLen] 1364 ]
Sandboxed Prolog code
Prolog is a full-featured Turing complete programming language in which it is easy to write programs that can harm your computer. On the other hand, Prolog is a logic based query language which can be exploited to query data interactively from, e.g., the web. This library provides safe_goal/1, which determines whether it is safe to call its argument.