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('$dicts':'.'(_,K,_)) :- 707 ( nonvar(K) 708 -> dict_built_in(K) 709 ; instantiation_error(K) 710 ). 711 712dict_built_in(get(_)). 713dict_built_in(get(_,_)). 714dict_built_in(put(_)). 715dict_built_in(put(_,_)). 716 717% The non-ISO system predicates. These can be redefined, so we must 718% be careful to ensure the system ones are used. 719 720safe_primitive(system:false). 721safe_primitive(system:cyclic_term(_)). 722safe_primitive(system:msort(_,_)). 723safe_primitive(system:sort(_,_,_,_)). 724safe_primitive(system:between(_,_,_)). 725safe_primitive(system:succ(_,_)). 726safe_primitive(system:plus(_,_,_)). 727safe_primitive(system:float_class(_,_)). 728safe_primitive(system:term_variables(_,_)). 729safe_primitive(system:term_variables(_,_,_)). 730safe_primitive(system:'$term_size'(_,_,_)). 731safe_primitive(system:atom_to_term(_,_,_)). 732safe_primitive(system:term_to_atom(_,_)). 733safe_primitive(system:atomic_list_concat(_,_,_)). 734safe_primitive(system:atomic_list_concat(_,_)). 735safe_primitive(system:downcase_atom(_,_)). 736safe_primitive(system:upcase_atom(_,_)). 737safe_primitive(system:is_list(_)). 738safe_primitive(system:memberchk(_,_)). 739safe_primitive(system:'$skip_list'(_,_,_)). 740safe_primitive(system:'$seek_list'(_, _, _, _)). 741 % attributes 742safe_primitive(system:get_attr(_,_,_)). 743safe_primitive(system:get_attrs(_,_)). 744safe_primitive(system:term_attvars(_,_)). 745safe_primitive(system:del_attr(_,_)). 746safe_primitive(system:del_attrs(_)). 747safe_primitive('$attvar':copy_term(_,_,_)). 748 % globals 749safe_primitive(system:b_getval(_,_)). 750safe_primitive(system:b_setval(Var,_)) :- 751 safe_global_var(Var). 752safe_primitive(system:nb_getval(_,_)). 753safe_primitive('$syspreds':nb_setval(Var,_)) :- 754 safe_global_var(Var). 755safe_primitive(system:nb_linkval(Var,_)) :- 756 safe_global_var(Var). 757safe_primitive(system:nb_current(_,_)). 758 % database 759safe_primitive(system:assert(X)) :- 760 safe_assert(X). 761 % Output 762safe_primitive(system:writeln(_)). 763safe_primitive('$messages':print_message(_,_)). 764 765 % Stack limits (down) 766safe_primitive('$syspreds':set_prolog_stack(Stack, limit(ByteExpr))) :- 767 nonvar(Stack), 768 stack_name(Stack), 769 catch(Bytes is ByteExpr, _, fail), 770 prolog_stack_property(Stack, limit(Current)), 771 Bytes =< Current. 772 773stack_name(global). 774stack_name(local). 775stack_name(trail). 776 777safe_primitive('$tabling':abolish_all_tables). 778safe_primitive('$tabling':'$wrap_tabled'(Module:_Head, _Mode)) :- 779 prolog_load_context(module, Module), 780 !. 781safe_primitive('$tabling':'$moded_wrap_tabled'(Module:_Head,_,_,_,_)) :- 782 prolog_load_context(module, Module), 783 !. 784 785 786% use_module/1. We only allow for .pl files that are loaded from 787% relative paths that do not contain /../ 788 789safe_primitive(system:use_module(Spec, _Import)) :- 790 safe_primitive(system:use_module(Spec)). 791safe_primitive(system:load_files(Spec, Options)) :- 792 safe_primitive(system:use_module(Spec)), 793 maplist(safe_load_file_option, Options). 794safe_primitive(system:use_module(Spec)) :- 795 ground(Spec), 796 ( atom(Spec) 797 -> Path = Spec 798 ; Spec =.. [_Alias, Segments], 799 phrase(segments_to_path(Segments), List), 800 atomic_list_concat(List, Path) 801 ), 802 \+ is_absolute_file_name(Path), 803 \+ sub_atom(Path, _, _, _, '/../'), 804 absolute_file_name(Spec, AbsFile, 805 [ access(read), 806 file_type(prolog), 807 file_errors(fail) 808 ]), 809 file_name_extension(_, Ext, AbsFile), 810 save_extension(Ext). 811 812% support predicates for safe_primitive, validating the safety of 813% arguments to certain goals. 814 815segments_to_path(A/B) --> 816 !, 817 segments_to_path(A), 818 [/], 819 segments_to_path(B). 820segments_to_path(X) --> 821 [X]. 822 823save_extension(pl). 824 825safe_load_file_option(if(changed)). 826safe_load_file_option(if(not_loaded)). 827safe_load_file_option(must_be_module(_)). 828safe_load_file_option(optimise(_)). 829safe_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.838safe_assert(C) :- cyclic_term(C), !, fail. 839safe_assert(X) :- var(X), !, fail. 840safe_assert(_Head:-_Body) :- !, fail. 841safe_assert(_:_) :- !, fail. 842safe_assert(_).
850safe_clause(H) :- var(H), !. 851safe_clause(_:_) :- !, fail. 852safe_clause(_).
860safe_global_var(Name) :- 861 var(Name), 862 !, 863 instantiation_error(Name). 864safe_global_var(Name) :- 865 safe_global_variable(Name).
875safe_current_predicate(X) :- 876 nonvar(X), 877 X = _:_, !, 878 fail. 879safe_current_predicate(_).
886safe_meta(system:put_attr(V,M,A), Called) :- 887 !, 888 ( atom(M) 889 -> attr_hook_predicates([ attr_unify_hook(A, _), 890 attribute_goals(V,_,_), 891 project_attributes(_,_) 892 ], M, Called) 893 ; instantiation_error(M) 894 ). 895safe_meta(system:with_output_to(Output, G), [G]) :- 896 safe_output(Output), 897 !. 898safe_meta(system:format(Format, Args), Calls) :- 899 format_calls(Format, Args, Calls). 900safe_meta(system:format(Output, Format, Args), Calls) :- 901 safe_output(Output), 902 format_calls(Format, Args, Calls). 903safe_meta(prolog_debug:debug(_Term, Format, Args), Calls) :- 904 format_calls(Format, Args, Calls). 905safe_meta(system:set_prolog_flag(Flag, Value), []) :- 906 atom(Flag), 907 safe_prolog_flag(Flag, Value). 908safe_meta('$attvar':freeze(_Var,Goal), [Goal]). 909safe_meta(phrase(NT,Xs0,Xs), [Goal]) :- % phrase/2,3 and call_dcg/2,3 910 expand_nt(NT,Xs0,Xs,Goal). 911safe_meta(phrase(NT,Xs0), [Goal]) :- 912 expand_nt(NT,Xs0,[],Goal). 913safe_meta('$dcg':call_dcg(NT,Xs0,Xs), [Goal]) :- 914 expand_nt(NT,Xs0,Xs,Goal). 915safe_meta('$dcg':call_dcg(NT,Xs0), [Goal]) :- 916 expand_nt(NT,Xs0,[],Goal). 917safe_meta('$tabling':abolish_table_subgoals(V), []) :- 918 \+ qualified(V). 919safe_meta('$tabling':current_table(V, _), []) :- 920 \+ qualified(V). 921safe_meta('$tabling':tnot(G), [G]). 922safe_meta('$tabling':not_exists(G), [G]). 923 924qualified(V) :- 925 nonvar(V), 926 V = _:_.
936attr_hook_predicates([], _, []). 937attr_hook_predicates([H|T], M, Called) :- 938 ( predicate_property(M:H, defined) 939 -> Called = [M:H|Rest] 940 ; Called = Rest 941 ), 942 attr_hook_predicates(T, M, Rest).
950expand_nt(NT, _Xs0, _Xs, _NewGoal) :- 951 strip_module(NT, _, Plain), 952 var(Plain), 953 !, 954 instantiation_error(Plain). 955expand_nt(NT, Xs0, Xs, NewGoal) :- 956 dcg_translate_rule((pseudo_nt --> NT), 957 (pseudo_nt(Xs0c,Xsc) :- NewGoal0)), 958 ( var(Xsc), Xsc \== Xs0c 959 -> Xs = Xsc, NewGoal1 = NewGoal0 960 ; NewGoal1 = (NewGoal0, Xsc = Xs) 961 ), 962 ( var(Xs0c) 963 -> Xs0 = Xs0c, 964 NewGoal = NewGoal1 965 ; NewGoal = ( Xs0 = Xs0c, NewGoal1 ) 966 ).
973safe_meta_call(Goal, _, _Called) :- 974 debug(sandbox(meta), 'Safe meta ~p?', [Goal]), 975 fail. 976safe_meta_call(Goal, Context, Called) :- 977 ( safe_meta(Goal, Called) 978 -> true 979 ; safe_meta(Goal, Context, Called) 980 ), 981 !. % call hook 982safe_meta_call(Goal, _, Called) :- 983 Goal = M:Plain, 984 compound(Plain), 985 compound_name_arity(Plain, Name, Arity), 986 safe_meta_predicate(M:Name/Arity), 987 predicate_property(Goal, meta_predicate(Spec)), 988 !, 989 called(Spec, Plain, Called). 990safe_meta_call(M:Goal, _, Called) :- 991 !, 992 generic_goal(Goal, Gen), 993 safe_meta(M:Gen), 994 called(Gen, Goal, Called). 995safe_meta_call(Goal, _, Called) :- 996 generic_goal(Goal, Gen), 997 safe_meta(Gen), 998 called(Gen, Goal, Called). 999 1000called(Gen, Goal, Called) :- 1001 compound_name_arity(Goal, _, Arity), 1002 called(1, Arity, Gen, Goal, Called). 1003 1004called(I, Arity, Gen, Goal, Called) :- 1005 I =< Arity, 1006 !, 1007 arg(I, Gen, Spec), 1008 ( calling_meta_spec(Spec) 1009 -> arg(I, Goal, Called0), 1010 extend(Spec, Called0, G), 1011 Called = [G|Rest] 1012 ; Called = Rest 1013 ), 1014 I2 is I+1, 1015 called(I2, Arity, Gen, Goal, Rest). 1016called(_, _, _, _, []). 1017 1018generic_goal(G, Gen) :- 1019 functor(G, Name, Arity), 1020 functor(Gen, Name, Arity). 1021 1022calling_meta_spec(V) :- var(V), !, fail. 1023calling_meta_spec(I) :- integer(I), !. 1024calling_meta_spec(^). 1025calling_meta_spec(//). 1026 1027 1028extend(^, G, Plain) :- 1029 !, 1030 strip_existential(G, Plain). 1031extend(//, DCG, Goal) :- 1032 !, 1033 ( expand_phrase(call_dcg(DCG,_,_), Goal) 1034 -> true 1035 ; instantiation_error(DCG) % Ask more instantiation. 1036 ). % might not help, but does not harm. 1037extend(0, G, G) :- !. 1038extend(I, M:G0, M:G) :- 1039 !, 1040 G0 =.. List, 1041 length(Extra, I), 1042 append(List, Extra, All), 1043 G =.. All. 1044extend(I, G0, G) :- 1045 G0 =.. List, 1046 length(Extra, I), 1047 append(List, Extra, All), 1048 G =.. All. 1049 1050strip_existential(Var, Var) :- 1051 var(Var), 1052 !. 1053strip_existential(M:G0, M:G) :- 1054 !, 1055 strip_existential(G0, G). 1056strip_existential(_^G0, G) :- 1057 !, 1058 strip_existential(G0, G). 1059strip_existential(G, G).
1063safe_meta((0,0)). 1064safe_meta((0;0)). 1065safe_meta((0->0)). 1066safe_meta(system:(0*->0)). 1067safe_meta(catch(0,*,0)). 1068safe_meta(findall(*,0,*)). 1069safe_meta('$bags':findall(*,0,*,*)). 1070safe_meta(setof(*,^,*)). 1071safe_meta(bagof(*,^,*)). 1072safe_meta('$bags':findnsols(*,*,0,*)). 1073safe_meta('$bags':findnsols(*,*,0,*,*)). 1074safe_meta(system:call_cleanup(0,0)). 1075safe_meta(system:setup_call_cleanup(0,0,0)). 1076safe_meta(system:setup_call_catcher_cleanup(0,0,*,0)). 1077safe_meta('$attvar':call_residue_vars(0,*)). 1078safe_meta('$syspreds':call_with_inference_limit(0,*,*)). 1079safe_meta('$syspreds':call_with_depth_limit(0,*,*)). 1080safe_meta('$syspreds':undo(0)). 1081safe_meta(^(*,0)). 1082safe_meta(\+(0)). 1083safe_meta(call(0)). 1084safe_meta(call(1,*)). 1085safe_meta(call(2,*,*)). 1086safe_meta(call(3,*,*,*)). 1087safe_meta(call(4,*,*,*,*)). 1088safe_meta(call(5,*,*,*,*,*)). 1089safe_meta(call(6,*,*,*,*,*,*)). 1090safe_meta('$tabling':start_tabling(*,0)). 1091safe_meta('$tabling':start_tabling(*,0,*,*)). 1092safe_meta(wfs:call_delays(0,*)).
1099safe_output(Output) :- 1100 var(Output), 1101 !, 1102 instantiation_error(Output). 1103safe_output(atom(_)). 1104safe_output(string(_)). 1105safe_output(codes(_)). 1106safe_output(codes(_,_)). 1107safe_output(chars(_)). 1108safe_output(chars(_,_)). 1109safe_output(current_output). 1110safe_output(current_error).
1116:- public format_calls/3. % used in pengines_io 1117 1118format_calls(Format, Args, Calls) :- 1119 is_list(Args), 1120 !, 1121 format_types(Format, Types), 1122 ( format_callables(Types, Args, Calls) 1123 -> true 1124 ; throw(error(format_error(Format, Types, Args), _)) 1125 ). 1126format_calls(Format, Arg, Calls) :- 1127 format_calls(Format, [Arg], Calls). 1128 1129format_callables([], [], []). 1130format_callables([callable|TT], [G|TA], [G|TG]) :- 1131 !, 1132 format_callables(TT, TA, TG). 1133format_callables([_|TT], [_|TA], TG) :- 1134 !, 1135 format_callables(TT, TA, TG). 1136 1137 1138 /******************************* 1139 * SAFE COMPILATION HOOKS * 1140 *******************************/ 1141 1142:- multifile 1143 prolog:sandbox_allowed_directive/1, 1144 prolog:sandbox_allowed_goal/1, 1145 prolog:sandbox_allowed_expansion/1.
1151prologsandbox_allowed_directive(Directive) :- 1152 debug(sandbox(directive), 'Directive: ~p', [Directive]), 1153 fail. 1154prologsandbox_allowed_directive(Directive) :- 1155 safe_directive(Directive), 1156 !. 1157prologsandbox_allowed_directive(M:PredAttr) :- 1158 \+ prolog_load_context(module, M), 1159 !, 1160 debug(sandbox(directive), 'Cross-module directive', []), 1161 permission_error(execute, sandboxed_directive, (:- M:PredAttr)). 1162prologsandbox_allowed_directive(M:PredAttr) :- 1163 safe_pattr(PredAttr), 1164 !, 1165 PredAttr =.. [Attr, Preds], 1166 ( safe_pattr(Preds, Attr) 1167 -> true 1168 ; permission_error(execute, sandboxed_directive, (:- M:PredAttr)) 1169 ). 1170prologsandbox_allowed_directive(_:Directive) :- 1171 safe_source_directive(Directive), 1172 !. 1173prologsandbox_allowed_directive(_:Directive) :- 1174 directive_loads_file(Directive, File), 1175 !, 1176 safe_path(File). 1177prologsandbox_allowed_directive(G) :- 1178 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),
...
1196safe_pattr(dynamic(_)). 1197safe_pattr(thread_local(_)). 1198safe_pattr(volatile(_)). 1199safe_pattr(discontiguous(_)). 1200safe_pattr(multifile(_)). 1201safe_pattr(public(_)). 1202safe_pattr(meta_predicate(_)). 1203safe_pattr(table(_)). 1204safe_pattr(non_terminal(_)). 1205 1206safe_pattr(Var, _) :- 1207 var(Var), 1208 !, 1209 instantiation_error(Var). 1210safe_pattr((A,B), Attr) :- 1211 !, 1212 safe_pattr(A, Attr), 1213 safe_pattr(B, Attr). 1214safe_pattr(M:G, Attr) :- 1215 !, 1216 ( atom(M), 1217 prolog_load_context(module, M) 1218 -> true 1219 ; Goal =.. [Attr,M:G], 1220 permission_error(directive, sandboxed, (:- Goal)) 1221 ). 1222safe_pattr(_, _). 1223 1224safe_source_directive(op(_,_,Name)) :- 1225 !, 1226 ( atom(Name) 1227 -> true 1228 ; is_list(Name), 1229 maplist(atom, Name) 1230 ). 1231safe_source_directive(set_prolog_flag(Flag, Value)) :- 1232 !, 1233 atom(Flag), ground(Value), 1234 safe_prolog_flag(Flag, Value). 1235safe_source_directive(style_check(_)). 1236safe_source_directive(initialization(_)). % Checked at runtime 1237safe_source_directive(initialization(_,_)). % Checked at runtime 1238 1239directive_loads_file(use_module(library(X)), X). 1240directive_loads_file(use_module(library(X), _Imports), X). 1241directive_loads_file(load_files(library(X), _Options), X). 1242directive_loads_file(ensure_loaded(library(X)), X). 1243directive_loads_file(include(X), X). 1244 1245safe_path(X) :- 1246 var(X), 1247 !, 1248 instantiation_error(X). 1249safe_path(X) :- 1250 ( atom(X) 1251 ; string(X) 1252 ), 1253 !, 1254 \+ sub_atom(X, 0, _, 0, '..'), 1255 \+ sub_atom(X, 0, _, _, '/'), 1256 \+ sub_atom(X, 0, _, _, '../'), 1257 \+ sub_atom(X, _, _, 0, '/..'), 1258 \+ sub_atom(X, _, _, _, '/../'). 1259safe_path(A/B) :- 1260 !, 1261 safe_path(A), 1262 safe_path(B).
1274% misc 1275safe_prolog_flag(generate_debug_info, _). 1276safe_prolog_flag(optimise, _). 1277safe_prolog_flag(occurs_check, _). 1278safe_prolog_flag(write_attributes, _). 1279% syntax 1280safe_prolog_flag(var_prefix, _). 1281safe_prolog_flag(double_quotes, _). 1282safe_prolog_flag(back_quotes, _). 1283safe_prolog_flag(rational_syntax, _). 1284% arithmetic 1285safe_prolog_flag(prefer_rationals, _). 1286safe_prolog_flag(float_overflow, _). 1287safe_prolog_flag(float_zero_div, _). 1288safe_prolog_flag(float_undefined, _). 1289safe_prolog_flag(float_underflow, _). 1290safe_prolog_flag(float_rounding, _). 1291safe_prolog_flag(float_rounding, _). 1292safe_prolog_flag(max_rational_size, _). 1293safe_prolog_flag(max_rational_size_action, _). 1294% tabling 1295safe_prolog_flag(max_answers_for_subgoal,_). 1296safe_prolog_flag(max_answers_for_subgoal_action,_). 1297safe_prolog_flag(max_table_answer_size,_). 1298safe_prolog_flag(max_table_answer_size_action,_). 1299safe_prolog_flag(max_table_subgoal_size,_). 1300safe_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.
1316prologsandbox_allowed_expansion(M:G) :- 1317 prolog_load_context(module, M), 1318 !, 1319 debug(sandbox(expansion), 'Expand in ~p: ~p', [M, G]), 1320 safe_goal(M:G). 1321prologsandbox_allowed_expansion(_,_).
1327prologsandbox_allowed_goal(G) :- 1328 safe_goal(G). 1329 1330 1331 /******************************* 1332 * MESSAGES * 1333 *******************************/ 1334 1335:- multifile 1336 prolog:message//1, 1337 prolog:message_context//1, 1338 prolog:error_message//1. 1339 1340prologmessage(error(instantiation_error, Context)) --> 1341 { nonvar(Context), 1342 Context = sandbox(_Goal,Parents), 1343 numbervars(Context, 1, _) 1344 }, 1345 [ 'Sandbox restriction!'-[], nl, 1346 'Could not derive which predicate may be called from'-[] 1347 ], 1348 ( { Parents == [] } 1349 -> [ 'Search space too large'-[] ] 1350 ; callers(Parents, 10) 1351 ). 1352 1353prologmessage_context(sandbox(_G, [])) --> !. 1354prologmessage_context(sandbox(_G, Parents)) --> 1355 [ nl, 'Reachable from:'-[] ], 1356 callers(Parents, 10). 1357 1358callers([], _) --> !. 1359callers(_, 0) --> !. 1360callers([G|Parents], Level) --> 1361 { NextLevel is Level-1 1362 }, 1363 [ nl, '\t ~p'-[G] ], 1364 callers(Parents, NextLevel). 1365 1366prologmessage(bad_safe_declaration(Goal, File, Line)) --> 1367 [ '~w:~d: Invalid safe_primitive/1 declaration: ~p'- 1368 [File, Line, Goal] ]. 1369 1370prologerror_message(format_error(Format, Types, Args)) --> 1371 format_error(Format, Types, Args). 1372 1373format_error(Format, Types, Args) --> 1374 { length(Types, TypeLen), 1375 length(Args, ArgsLen), 1376 ( TypeLen > ArgsLen 1377 -> Problem = 'not enough' 1378 ; Problem = 'too many' 1379 ) 1380 }, 1381 [ 'format(~q): ~w arguments (found ~w, need ~w)'- 1382 [Format, Problem, ArgsLen, TypeLen] 1383 ]
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.