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) 2013-2023, 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. 572safe_primitive(system:current_arithmetic_function(_)). 573safe_primitive(system:bounded_number(_,_,_)). 574safe_primitive(system:float_class(_,_)). 575safe_primitive(system:float_parts(_,_,_,_)). 576 577 % term-handling 578safe_primitive(arg(_,_,_)). 579safe_primitive(system:setarg(_,_,_)). 580safe_primitive(system:nb_setarg(_,_,_)). 581safe_primitive(system:nb_linkarg(_,_,_)). 582safe_primitive(functor(_,_,_)). 583safe_primitive(system:functor(_,_,_,_)). 584safe_primitive(_ =.. _). 585safe_primitive(system:compound_name_arity(_,_,_)). 586safe_primitive(system:compound_name_arguments(_,_,_)). 587safe_primitive(system:'$filled_array'(_,_,_,_)). 588safe_primitive(copy_term(_,_)). 589safe_primitive(system:copy_term(_,_,_,_)). 590safe_primitive(system:duplicate_term(_,_)). 591safe_primitive(system:copy_term_nat(_,_)). 592safe_primitive(system:size_abstract_term(_,_,_)). 593safe_primitive(numbervars(_,_,_)). 594safe_primitive(system:numbervars(_,_,_,_)). 595safe_primitive(subsumes_term(_,_)). 596safe_primitive(system:term_hash(_,_)). 597safe_primitive(system:term_hash(_,_,_,_)). 598safe_primitive(system:variant_sha1(_,_)). 599safe_primitive(system:variant_hash(_,_)). 600safe_primitive(system:'$term_size'(_,_,_)). 601 602 % dicts 603safe_primitive(system:is_dict(_)). 604safe_primitive(system:is_dict(_,_)). 605safe_primitive(system:get_dict(_,_,_)). 606safe_primitive(system:get_dict(_,_,_,_,_)). 607safe_primitive(system:'$get_dict_ex'(_,_,_)). 608safe_primitive(system:dict_create(_,_,_)). 609safe_primitive(system:dict_pairs(_,_,_)). 610safe_primitive(system:put_dict(_,_,_)). 611safe_primitive(system:put_dict(_,_,_,_)). 612safe_primitive(system:del_dict(_,_,_,_)). 613safe_primitive(system:select_dict(_,_,_)). 614safe_primitive(system:b_set_dict(_,_,_)). 615safe_primitive(system:nb_set_dict(_,_,_)). 616safe_primitive(system:nb_link_dict(_,_,_)). 617safe_primitive(system:(:<(_,_))). 618safe_primitive(system:(>:<(_,_))). 619 % atoms 620safe_primitive(atom_chars(_, _)). 621safe_primitive(atom_codes(_, _)). 622safe_primitive(sub_atom(_,_,_,_,_)). 623safe_primitive(atom_concat(_,_,_)). 624safe_primitive(atom_length(_,_)). 625safe_primitive(char_code(_,_)). 626safe_primitive(system:name(_,_)). 627safe_primitive(system:atomic_concat(_,_,_)). 628safe_primitive(system:atomic_list_concat(_,_)). 629safe_primitive(system:atomic_list_concat(_,_,_)). 630safe_primitive(system:downcase_atom(_,_)). 631safe_primitive(system:upcase_atom(_,_)). 632safe_primitive(system:char_type(_,_)). 633safe_primitive(system:normalize_space(_,_)). 634safe_primitive(system:sub_atom_icasechk(_,_,_)). 635 % numbers 636safe_primitive(number_codes(_,_)). 637safe_primitive(number_chars(_,_)). 638safe_primitive(system:atom_number(_,_)). 639safe_primitive(system:code_type(_,_)). 640 % strings 641safe_primitive(system:atom_string(_,_)). 642safe_primitive(system:number_string(_,_)). 643safe_primitive(system:string_chars(_, _)). 644safe_primitive(system:string_codes(_, _)). 645safe_primitive(system:string_code(_,_,_)). 646safe_primitive(system:sub_string(_,_,_,_,_)). 647safe_primitive(system:split_string(_,_,_,_)). 648safe_primitive(system:atomics_to_string(_,_,_)). 649safe_primitive(system:atomics_to_string(_,_)). 650safe_primitive(system:string_concat(_,_,_)). 651safe_primitive(system:string_length(_,_)). 652safe_primitive(system:string_lower(_,_)). 653safe_primitive(system:string_upper(_,_)). 654safe_primitive(system:term_string(_,_)). 655safe_primitive('$syspreds':term_string(_,_,_)). 656 % Lists 657safe_primitive(length(_,_)). 658 % exceptions 659safe_primitive(throw(_)). 660safe_primitive(system:abort). 661 % misc 662safe_primitive(current_prolog_flag(_,_)). 663safe_primitive(current_op(_,_,_)). 664safe_primitive(system:sleep(_)). 665safe_primitive(system:thread_self(_)). 666safe_primitive(system:get_time(_)). 667safe_primitive(system:statistics(_,_)). 668:- if(current_prolog_flag(threads,true)). 669safe_primitive(system:thread_statistics(Id,_,_)) :- 670 ( var(Id) 671 -> instantiation_error(Id) 672 ; thread_self(Id) 673 ). 674safe_primitive(system:thread_property(Id,_)) :- 675 ( var(Id) 676 -> instantiation_error(Id) 677 ; thread_self(Id) 678 ). 679:- endif. 680safe_primitive(system:format_time(_,_,_)). 681safe_primitive(system:format_time(_,_,_,_)). 682safe_primitive(system:date_time_stamp(_,_)). 683safe_primitive(system:stamp_date_time(_,_,_)). 684safe_primitive(system:strip_module(_,_,_)). 685safe_primitive('$messages':message_to_string(_,_)). 686safe_primitive(system:import_module(_,_)). 687safe_primitive(system:file_base_name(_,_)). 688safe_primitive(system:file_directory_name(_,_)). 689safe_primitive(system:file_name_extension(_,_,_)). 690 691safe_primitive(clause(H,_)) :- safe_clause(H). 692safe_primitive(asserta(X)) :- safe_assert(X). 693safe_primitive(assertz(X)) :- safe_assert(X). 694safe_primitive(retract(X)) :- safe_assert(X). 695safe_primitive(retractall(X)) :- safe_assert(X). 696safe_primitive(current_predicate(X)) :- safe_current_predicate(X). 697safe_primitive('$dcg':dcg_translate_rule(_,_)). 698safe_primitive('$syspreds':predicate_property(Pred, _)) :- 699 nonvar(Pred), 700 Pred \= (_:_). 701 702% We need to do data flow analysis to find the tag of the 703% target key before we can conclude that functions on dicts 704% are safe. 705safe_primitive('$dicts':'.'(_,K,_)) :- atom(K). 706safe_primitive('$dicts':'.'(_,K,_)) :- 707 ( nonvar(K) 708 -> dict_built_in(K) 709 ; instantiation_error(K) 710 ). 711 712dict_built_in(get(_)). 713dict_built_in(put(_)). 714dict_built_in(put(_,_)). 715 716% The non-ISO system predicates. These can be redefined, so we must 717% be careful to ensure the system ones are used. 718 719safe_primitive(system:false). 720safe_primitive(system:cyclic_term(_)). 721safe_primitive(system:msort(_,_)). 722safe_primitive(system:sort(_,_,_,_)). 723safe_primitive(system:between(_,_,_)). 724safe_primitive(system:succ(_,_)). 725safe_primitive(system:plus(_,_,_)). 726safe_primitive(system:float_class(_,_)). 727safe_primitive(system:term_variables(_,_)). 728safe_primitive(system:term_variables(_,_,_)). 729safe_primitive(system:'$term_size'(_,_,_)). 730safe_primitive(system:atom_to_term(_,_,_)). 731safe_primitive(system:term_to_atom(_,_)). 732safe_primitive(system:atomic_list_concat(_,_,_)). 733safe_primitive(system:atomic_list_concat(_,_)). 734safe_primitive(system:downcase_atom(_,_)). 735safe_primitive(system:upcase_atom(_,_)). 736safe_primitive(system:is_list(_)). 737safe_primitive(system:memberchk(_,_)). 738safe_primitive(system:'$skip_list'(_,_,_)). 739safe_primitive(system:'$seek_list'(_, _, _, _)). 740 % attributes 741safe_primitive(system:get_attr(_,_,_)). 742safe_primitive(system:get_attrs(_,_)). 743safe_primitive(system:term_attvars(_,_)). 744safe_primitive(system:del_attr(_,_)). 745safe_primitive(system:del_attrs(_)). 746safe_primitive('$attvar':copy_term(_,_,_)). 747 % globals 748safe_primitive(system:b_getval(_,_)). 749safe_primitive(system:b_setval(Var,_)) :- 750 safe_global_var(Var). 751safe_primitive(system:nb_getval(_,_)). 752safe_primitive('$syspreds':nb_setval(Var,_)) :- 753 safe_global_var(Var). 754safe_primitive(system:nb_linkval(Var,_)) :- 755 safe_global_var(Var). 756safe_primitive(system:nb_current(_,_)). 757 % database 758safe_primitive(system:assert(X)) :- 759 safe_assert(X). 760 % Output 761safe_primitive(system:writeln(_)). 762safe_primitive('$messages':print_message(_,_)). 763 764 % Stack limits (down) 765safe_primitive('$syspreds':set_prolog_stack(Stack, limit(ByteExpr))) :- 766 nonvar(Stack), 767 stack_name(Stack), 768 catch(Bytes is ByteExpr, _, fail), 769 prolog_stack_property(Stack, limit(Current)), 770 Bytes =< Current. 771 772stack_name(global). 773stack_name(local). 774stack_name(trail). 775 776safe_primitive('$tabling':abolish_all_tables). 777safe_primitive('$tabling':'$wrap_tabled'(Module:_Head, _Mode)) :- 778 prolog_load_context(module, Module), 779 !. 780safe_primitive('$tabling':'$moded_wrap_tabled'(Module:_Head,_,_,_,_)) :- 781 prolog_load_context(module, Module), 782 !. 783 784 785% use_module/1. We only allow for .pl files that are loaded from 786% relative paths that do not contain /../ 787 788safe_primitive(system:use_module(Spec, _Import)) :- 789 safe_primitive(system:use_module(Spec)). 790safe_primitive(system:load_files(Spec, Options)) :- 791 safe_primitive(system:use_module(Spec)), 792 maplist(safe_load_file_option, Options). 793safe_primitive(system:use_module(Spec)) :- 794 ground(Spec), 795 ( atom(Spec) 796 -> Path = Spec 797 ; Spec =.. [_Alias, Segments], 798 phrase(segments_to_path(Segments), List), 799 atomic_list_concat(List, Path) 800 ), 801 \+ is_absolute_file_name(Path), 802 \+ sub_atom(Path, _, _, _, '/../'), 803 absolute_file_name(Spec, AbsFile, 804 [ access(read), 805 file_type(prolog), 806 file_errors(fail) 807 ]), 808 file_name_extension(_, Ext, AbsFile), 809 save_extension(Ext). 810 811% support predicates for safe_primitive, validating the safety of 812% arguments to certain goals. 813 814segments_to_path(A/B) --> 815 !, 816 segments_to_path(A), 817 [/], 818 segments_to_path(B). 819segments_to_path(X) --> 820 [X]. 821 822save_extension(pl). 823 824safe_load_file_option(if(changed)). 825safe_load_file_option(if(not_loaded)). 826safe_load_file_option(must_be_module(_)). 827safe_load_file_option(optimise(_)). 828safe_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.837safe_assert(C) :- cyclic_term(C), !, fail. 838safe_assert(X) :- var(X), !, fail. 839safe_assert(_Head:-_Body) :- !, fail. 840safe_assert(_:_) :- !, fail. 841safe_assert(_).
849safe_clause(H) :- var(H), !. 850safe_clause(_:_) :- !, fail. 851safe_clause(_).
859safe_global_var(Name) :- 860 var(Name), 861 !, 862 instantiation_error(Name). 863safe_global_var(Name) :- 864 safe_global_variable(Name).
874safe_current_predicate(X) :- 875 nonvar(X), 876 X = _:_, !, 877 fail. 878safe_current_predicate(_).
885safe_meta(system:put_attr(V,M,A), Called) :- 886 !, 887 ( atom(M) 888 -> attr_hook_predicates([ attr_unify_hook(A, _), 889 attribute_goals(V,_,_), 890 project_attributes(_,_) 891 ], M, Called) 892 ; instantiation_error(M) 893 ). 894safe_meta(system:with_output_to(Output, G), [G]) :- 895 safe_output(Output), 896 !. 897safe_meta(system:format(Format, Args), Calls) :- 898 format_calls(Format, Args, Calls). 899safe_meta(system:format(Output, Format, Args), Calls) :- 900 safe_output(Output), 901 format_calls(Format, Args, Calls). 902safe_meta(prolog_debug:debug(_Term, Format, Args), Calls) :- 903 format_calls(Format, Args, Calls). 904safe_meta(system:set_prolog_flag(Flag, Value), []) :- 905 atom(Flag), 906 safe_prolog_flag(Flag, Value). 907safe_meta('$attvar':freeze(_Var,Goal), [Goal]). 908safe_meta(phrase(NT,Xs0,Xs), [Goal]) :- % phrase/2,3 and call_dcg/2,3 909 expand_nt(NT,Xs0,Xs,Goal). 910safe_meta(phrase(NT,Xs0), [Goal]) :- 911 expand_nt(NT,Xs0,[],Goal). 912safe_meta('$dcg':call_dcg(NT,Xs0,Xs), [Goal]) :- 913 expand_nt(NT,Xs0,Xs,Goal). 914safe_meta('$dcg':call_dcg(NT,Xs0), [Goal]) :- 915 expand_nt(NT,Xs0,[],Goal). 916safe_meta('$tabling':abolish_table_subgoals(V), []) :- 917 \+ qualified(V). 918safe_meta('$tabling':current_table(V, _), []) :- 919 \+ qualified(V). 920safe_meta('$tabling':tnot(G), [G]). 921safe_meta('$tabling':not_exists(G), [G]). 922 923qualified(V) :- 924 nonvar(V), 925 V = _:_.
935attr_hook_predicates([], _, []). 936attr_hook_predicates([H|T], M, Called) :- 937 ( predicate_property(M:H, defined) 938 -> Called = [M:H|Rest] 939 ; Called = Rest 940 ), 941 attr_hook_predicates(T, M, Rest).
949expand_nt(NT, _Xs0, _Xs, _NewGoal) :- 950 strip_module(NT, _, Plain), 951 var(Plain), 952 !, 953 instantiation_error(Plain). 954expand_nt(NT, Xs0, Xs, NewGoal) :- 955 dcg_translate_rule((pseudo_nt --> NT), 956 (pseudo_nt(Xs0c,Xsc) :- NewGoal0)), 957 ( var(Xsc), Xsc \== Xs0c 958 -> Xs = Xsc, NewGoal1 = NewGoal0 959 ; NewGoal1 = (NewGoal0, Xsc = Xs) 960 ), 961 ( var(Xs0c) 962 -> Xs0 = Xs0c, 963 NewGoal = NewGoal1 964 ; NewGoal = ( Xs0 = Xs0c, NewGoal1 ) 965 ).
972safe_meta_call(Goal, _, _Called) :- 973 debug(sandbox(meta), 'Safe meta ~p?', [Goal]), 974 fail. 975safe_meta_call(Goal, Context, Called) :- 976 ( safe_meta(Goal, Called) 977 -> true 978 ; safe_meta(Goal, Context, Called) 979 ), 980 !. % call hook 981safe_meta_call(Goal, _, Called) :- 982 Goal = M:Plain, 983 compound(Plain), 984 compound_name_arity(Plain, Name, Arity), 985 safe_meta_predicate(M:Name/Arity), 986 predicate_property(Goal, meta_predicate(Spec)), 987 !, 988 called(Spec, Plain, Called). 989safe_meta_call(M:Goal, _, Called) :- 990 !, 991 generic_goal(Goal, Gen), 992 safe_meta(M:Gen), 993 called(Gen, Goal, Called). 994safe_meta_call(Goal, _, Called) :- 995 generic_goal(Goal, Gen), 996 safe_meta(Gen), 997 called(Gen, Goal, Called). 998 999called(Gen, Goal, Called) :- 1000 compound_name_arity(Goal, _, Arity), 1001 called(1, Arity, Gen, Goal, Called). 1002 1003called(I, Arity, Gen, Goal, Called) :- 1004 I =< Arity, 1005 !, 1006 arg(I, Gen, Spec), 1007 ( calling_meta_spec(Spec) 1008 -> arg(I, Goal, Called0), 1009 extend(Spec, Called0, G), 1010 Called = [G|Rest] 1011 ; Called = Rest 1012 ), 1013 I2 is I+1, 1014 called(I2, Arity, Gen, Goal, Rest). 1015called(_, _, _, _, []). 1016 1017generic_goal(G, Gen) :- 1018 functor(G, Name, Arity), 1019 functor(Gen, Name, Arity). 1020 1021calling_meta_spec(V) :- var(V), !, fail. 1022calling_meta_spec(I) :- integer(I), !. 1023calling_meta_spec(^). 1024calling_meta_spec(//). 1025 1026 1027extend(^, G, Plain) :- 1028 !, 1029 strip_existential(G, Plain). 1030extend(//, DCG, Goal) :- 1031 !, 1032 ( expand_phrase(call_dcg(DCG,_,_), Goal) 1033 -> true 1034 ; instantiation_error(DCG) % Ask more instantiation. 1035 ). % might not help, but does not harm. 1036extend(0, G, G) :- !. 1037extend(I, M:G0, M:G) :- 1038 !, 1039 G0 =.. List, 1040 length(Extra, I), 1041 append(List, Extra, All), 1042 G =.. All. 1043extend(I, G0, G) :- 1044 G0 =.. List, 1045 length(Extra, I), 1046 append(List, Extra, All), 1047 G =.. All. 1048 1049strip_existential(Var, Var) :- 1050 var(Var), 1051 !. 1052strip_existential(M:G0, M:G) :- 1053 !, 1054 strip_existential(G0, G). 1055strip_existential(_^G0, G) :- 1056 !, 1057 strip_existential(G0, G). 1058strip_existential(G, G).
1062safe_meta((0,0)). 1063safe_meta((0;0)). 1064safe_meta((0->0)). 1065safe_meta(system:(0*->0)). 1066safe_meta(catch(0,*,0)). 1067safe_meta(findall(*,0,*)). 1068safe_meta('$bags':findall(*,0,*,*)). 1069safe_meta(setof(*,^,*)). 1070safe_meta(bagof(*,^,*)). 1071safe_meta('$bags':findnsols(*,*,0,*)). 1072safe_meta('$bags':findnsols(*,*,0,*,*)). 1073safe_meta(system:call_cleanup(0,0)). 1074safe_meta(system:setup_call_cleanup(0,0,0)). 1075safe_meta(system:setup_call_catcher_cleanup(0,0,*,0)). 1076safe_meta('$attvar':call_residue_vars(0,*)). 1077safe_meta('$syspreds':call_with_inference_limit(0,*,*)). 1078safe_meta('$syspreds':call_with_depth_limit(0,*,*)). 1079safe_meta('$syspreds':undo(0)). 1080safe_meta(^(*,0)). 1081safe_meta(\+(0)). 1082safe_meta(call(0)). 1083safe_meta(call(1,*)). 1084safe_meta(call(2,*,*)). 1085safe_meta(call(3,*,*,*)). 1086safe_meta(call(4,*,*,*,*)). 1087safe_meta(call(5,*,*,*,*,*)). 1088safe_meta(call(6,*,*,*,*,*,*)). 1089safe_meta('$tabling':start_tabling(*,0)). 1090safe_meta('$tabling':start_tabling(*,0,*,*)). 1091safe_meta(wfs:call_delays(0,*)).
1098safe_output(Output) :- 1099 var(Output), 1100 !, 1101 instantiation_error(Output). 1102safe_output(atom(_)). 1103safe_output(string(_)). 1104safe_output(codes(_)). 1105safe_output(codes(_,_)). 1106safe_output(chars(_)). 1107safe_output(chars(_,_)). 1108safe_output(current_output). 1109safe_output(current_error).
1115:- public format_calls/3. % used in pengines_io 1116 1117format_calls(Format, Args, Calls) :- 1118 is_list(Args), 1119 !, 1120 format_types(Format, Types), 1121 ( format_callables(Types, Args, Calls) 1122 -> true 1123 ; throw(error(format_error(Format, Types, Args), _)) 1124 ). 1125format_calls(Format, Arg, Calls) :- 1126 format_calls(Format, [Arg], Calls). 1127 1128format_callables([], [], []). 1129format_callables([callable|TT], [G|TA], [G|TG]) :- 1130 !, 1131 format_callables(TT, TA, TG). 1132format_callables([_|TT], [_|TA], TG) :- 1133 !, 1134 format_callables(TT, TA, TG). 1135 1136 1137 /******************************* 1138 * SAFE COMPILATION HOOKS * 1139 *******************************/ 1140 1141:- multifile 1142 prolog:sandbox_allowed_directive/1, 1143 prolog:sandbox_allowed_goal/1, 1144 prolog:sandbox_allowed_expansion/1.
1150prologsandbox_allowed_directive(Directive) :- 1151 debug(sandbox(directive), 'Directive: ~p', [Directive]), 1152 fail. 1153prologsandbox_allowed_directive(Directive) :- 1154 safe_directive(Directive), 1155 !. 1156prologsandbox_allowed_directive(M:PredAttr) :- 1157 \+ prolog_load_context(module, M), 1158 !, 1159 debug(sandbox(directive), 'Cross-module directive', []), 1160 permission_error(execute, sandboxed_directive, (:- M:PredAttr)). 1161prologsandbox_allowed_directive(M:PredAttr) :- 1162 safe_pattr(PredAttr), 1163 !, 1164 PredAttr =.. [Attr, Preds], 1165 ( safe_pattr(Preds, Attr) 1166 -> true 1167 ; permission_error(execute, sandboxed_directive, (:- M:PredAttr)) 1168 ). 1169prologsandbox_allowed_directive(_:Directive) :- 1170 safe_source_directive(Directive), 1171 !. 1172prologsandbox_allowed_directive(_:Directive) :- 1173 directive_loads_file(Directive, File), 1174 !, 1175 safe_path(File). 1176prologsandbox_allowed_directive(G) :- 1177 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),
...
1195safe_pattr(dynamic(_)). 1196safe_pattr(thread_local(_)). 1197safe_pattr(volatile(_)). 1198safe_pattr(discontiguous(_)). 1199safe_pattr(multifile(_)). 1200safe_pattr(public(_)). 1201safe_pattr(meta_predicate(_)). 1202safe_pattr(table(_)). 1203safe_pattr(non_terminal(_)). 1204 1205safe_pattr(Var, _) :- 1206 var(Var), 1207 !, 1208 instantiation_error(Var). 1209safe_pattr((A,B), Attr) :- 1210 !, 1211 safe_pattr(A, Attr), 1212 safe_pattr(B, Attr). 1213safe_pattr(M:G, Attr) :- 1214 !, 1215 ( atom(M), 1216 prolog_load_context(module, M) 1217 -> true 1218 ; Goal =.. [Attr,M:G], 1219 permission_error(directive, sandboxed, (:- Goal)) 1220 ). 1221safe_pattr(_, _). 1222 1223safe_source_directive(op(_,_,Name)) :- 1224 !, 1225 ( atom(Name) 1226 -> true 1227 ; is_list(Name), 1228 maplist(atom, Name) 1229 ). 1230safe_source_directive(set_prolog_flag(Flag, Value)) :- 1231 !, 1232 atom(Flag), ground(Value), 1233 safe_prolog_flag(Flag, Value). 1234safe_source_directive(style_check(_)). 1235safe_source_directive(initialization(_)). % Checked at runtime 1236safe_source_directive(initialization(_,_)). % Checked at runtime 1237 1238directive_loads_file(use_module(library(X)), X). 1239directive_loads_file(use_module(library(X), _Imports), X). 1240directive_loads_file(load_files(library(X), _Options), X). 1241directive_loads_file(ensure_loaded(library(X)), X). 1242directive_loads_file(include(X), X). 1243 1244safe_path(X) :- 1245 var(X), 1246 !, 1247 instantiation_error(X). 1248safe_path(X) :- 1249 ( atom(X) 1250 ; string(X) 1251 ), 1252 !, 1253 \+ sub_atom(X, 0, _, 0, '..'), 1254 \+ sub_atom(X, 0, _, _, '/'), 1255 \+ sub_atom(X, 0, _, _, '../'), 1256 \+ sub_atom(X, _, _, 0, '/..'), 1257 \+ sub_atom(X, _, _, _, '/../'). 1258safe_path(A/B) :- 1259 !, 1260 safe_path(A), 1261 safe_path(B).
1273% misc 1274safe_prolog_flag(generate_debug_info, _). 1275safe_prolog_flag(optimise, _). 1276safe_prolog_flag(occurs_check, _). 1277safe_prolog_flag(write_attributes, _). 1278% syntax 1279safe_prolog_flag(var_prefix, _). 1280safe_prolog_flag(double_quotes, _). 1281safe_prolog_flag(back_quotes, _). 1282safe_prolog_flag(rational_syntax, _). 1283% arithmetic 1284safe_prolog_flag(prefer_rationals, _). 1285safe_prolog_flag(float_overflow, _). 1286safe_prolog_flag(float_zero_div, _). 1287safe_prolog_flag(float_undefined, _). 1288safe_prolog_flag(float_underflow, _). 1289safe_prolog_flag(float_rounding, _). 1290safe_prolog_flag(float_rounding, _). 1291safe_prolog_flag(max_rational_size, _). 1292safe_prolog_flag(max_rational_size_action, _). 1293% tabling 1294safe_prolog_flag(max_answers_for_subgoal,_). 1295safe_prolog_flag(max_answers_for_subgoal_action,_). 1296safe_prolog_flag(max_table_answer_size,_). 1297safe_prolog_flag(max_table_answer_size_action,_). 1298safe_prolog_flag(max_table_subgoal_size,_). 1299safe_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.
1315prologsandbox_allowed_expansion(M:G) :- 1316 prolog_load_context(module, M), 1317 !, 1318 debug(sandbox(expansion), 'Expand in ~p: ~p', [M, G]), 1319 safe_goal(M:G). 1320prologsandbox_allowed_expansion(_,_).
1326prologsandbox_allowed_goal(G) :- 1327 safe_goal(G). 1328 1329 1330 /******************************* 1331 * MESSAGES * 1332 *******************************/ 1333 1334:- multifile 1335 prolog:message//1, 1336 prolog:message_context//1, 1337 prolog:error_message//1. 1338 1339prologmessage(error(instantiation_error, Context)) --> 1340 { nonvar(Context), 1341 Context = sandbox(_Goal,Parents), 1342 numbervars(Context, 1, _) 1343 }, 1344 [ 'Sandbox restriction!'-[], nl, 1345 'Could not derive which predicate may be called from'-[] 1346 ], 1347 ( { Parents == [] } 1348 -> [ 'Search space too large'-[] ] 1349 ; callers(Parents, 10) 1350 ). 1351 1352prologmessage_context(sandbox(_G, [])) --> !. 1353prologmessage_context(sandbox(_G, Parents)) --> 1354 [ nl, 'Reachable from:'-[] ], 1355 callers(Parents, 10). 1356 1357callers([], _) --> !. 1358callers(_, 0) --> !. 1359callers([G|Parents], Level) --> 1360 { NextLevel is Level-1 1361 }, 1362 [ nl, '\t ~p'-[G] ], 1363 callers(Parents, NextLevel). 1364 1365prologmessage(bad_safe_declaration(Goal, File, Line)) --> 1366 [ '~w:~d: Invalid safe_primitive/1 declaration: ~p'- 1367 [File, Line, Goal] ]. 1368 1369prologerror_message(format_error(Format, Types, Args)) --> 1370 format_error(Format, Types, Args). 1371 1372format_error(Format, Types, Args) --> 1373 { length(Types, TypeLen), 1374 length(Args, ArgsLen), 1375 ( TypeLen > ArgsLen 1376 -> Problem = 'not enough' 1377 ; Problem = 'too many' 1378 ) 1379 }, 1380 [ 'format(~q): ~w arguments (found ~w, need ~w)'- 1381 [Format, Problem, ArgsLen, TypeLen] 1382 ]
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.